分类： 生物学 >> 生态学 提交时间： 2024-06-21 合作期刊: 《干旱区科学》
摘要： To comprehensively evaluate the alterations in water ecosystem service functions within arid watersheds, this study focused on the Bosten Lake Basin, which is situated in the arid region of Northwest China. The research was based on land use/land cover (LULC), natural, socioeconomic, and accessibility data, utilizing the Patch-level Land Use Simulation (PLUS) and Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) models to dynamically assess LULC change and associated variations in water yield and water conservation. The analyses included the evaluation of contribution indices of various land use types and the investigation of driving factors that influence water yield and water conservation. The results showed that the change of LULC in the Bosten Lake Basin from 2000 to 2020 showed a trend of increasing in cultivated land and construction land, and decreasing in grassland, forest, and unused land. The unused land of all the three predicted scenarios of 2030 (S1, a natural development scenario; S2, an ecological protection scenario; and S3, a cultivated land protection scenario) showed a decreasing trend. The scenarios S1 and S3 showed a trend of decreasing in grassland and increasing in cultivated land; while the scenario S2 showed a trend of decreasing in cultivated land and increasing in grassland. The water yield of the Bosten Lake Basin exhibited an initial decline followed by a slight increase from 2000 to 2020. The areas with higher water yield values were primarily located in the northern section of the basin, which is characterized by higher altitude. Water conservation demonstrated a pattern of initial decrease followed by stabilization, with the northeastern region demonstrating higher water conservation values. In the projected LULC scenarios of 2030, the estimated water yield under scenarios S1 and S3 was marginally greater than that under scenario S2; while the level of water conservation across all three scenarios remained rather consistent. The results showed that Hejing County is an important water conservation function zone, and the eastern part of the Xiaoyouledusi Basin is particularly important and should be protected. The findings of this study offer a scientific foundation for advancing sustainable development in arid watersheds and facilitating efficient water resource management.
分类： 地球科学 >> 地质学 提交时间： 2024-06-21 合作期刊: 《干旱区科学》
摘要： Quantifying surface cracks in alpine meadows is a prerequisite and a key aspect in the study of grassland crack development. Crack characterization indices are crucial for the quantitative characterization of complex cracks, serving as vital factors in assessing the degree of cracking and the development morphology. So far, research on evaluating the degree of grassland degradation through crack characterization indices is rare, especially the quantitative analysis of the development of surface cracks in alpine meadows is relatively scarce. Therefore, based on the phenomenon of surface cracking during the degradation of alpine meadows in some regions of the Qinghai-Tibet Plateau, we selected the alpine meadow in the Huangcheng Mongolian Township, Menyuan Hui Autonomous County, Qinghai Province, China as the study area, used unmanned aerial vehicle (UAV) sensing technology to acquire low-altitude images of alpine meadow surface cracks at different degrees of degradation (light, medium, and heavy degradation), and analyzed the representative metrics characterizing the degree of crack development by interpreting the crack length, length density, branch angle, and burrow (rat hole) distribution density and combining them with in situ crack width and depth measurements. Finally, the correlations between the crack characterization indices and the soil and root parameters of sample plots at different degrees of degradation in the study area were analyzed using the grey relation analysis. The results revealed that with the increase of degradation, the physical and chemical properties of soil and the mechanical properties of root-soil composite changed significantly, the vegetation coverage reduced, and the root system aggregated in the surface layer of alpine meadow. As the degree of degradation increased, the fracture morphology developed from "linear" to "dendritic", and eventually to a complex and irregular "polygonal" pattern. The crack length, width, depth, and length density were identified as the crack characterization indices via analysis of variance. The results of grey relation analysis also revealed that the crack length, width, depth, and length density were all highly correlated with root length density, and as the degradation of alpine meadows intensified, the underground biomass increased dramatically, forming a dense layer of grass felt, which has a significant impact on the formation and expansion of cracks.
分类： 生物学 >> 生态学 提交时间： 2024-06-21 合作期刊: 《干旱区科学》
摘要： Nature reserves play a significant role in providing ecosystem services and are key sites for biodiversity conservation. The Tianchi Bogda Peak Natural Reserve (TBPNR), located in Xinjiang Uygur Autonomous Region, China, is an important ecological barrier area in the temperate arid zone. The evaluation of its important ecosystem services is of great significance to improve the management level and ecological protection efficiency of the reserve. In the present study, we assessed the spatiotemporal variations of four ecosystem services (including net primary productivity (NPP), water yield, soil conservation, and habitat quality) in the TBPNR from 2000 to 2020 based on the environmental and social data using the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model. In addition, the coldspot and hotspot areas of ecosystem services were identified by hotspot analysis, and the trade-off and synergistic relationships between ecosystem services were analyzed using factor analysis in a geographic detector. During the study period, NPP and soil conservation values in the reserve increased by 48.20% and 25.56%, respectively; conversely, water yield decreased by 16.56%, and there was no significant change in habitat quality. Spatially, both NPP and habitat quality values were higher in the northern part and lower in the southern part, whereas water yield showed an opposite trend. Correlation analysis revealed that NPP showed a synergistic relationship with habitat quality and soil conservation, and exhibited a trade-off relationship with water yield. Water yield and habitat quality also had a trade-off relationship. NPP and habitat quality were affected by annual average temperature and Normalized Difference Vegetation Index (NDVI), respectively, while water yield and soil conservation were more affected by digital elevation model (DEM). Therefore, attention should be paid to the spatial distribution and dynamics of trade-off and synergistic relationships between ecosystem services in future ecological management. The findings of the present study provide a reference that could facilitate the sustainable utilization of ecosystem services in the typical fragile areas of Northwest China.
分类： 地球科学 >> 水文学 提交时间： 2024-06-21 合作期刊: 《干旱区科学》
摘要： Understanding the dynamics of surface water area and their drivers is crucial for human survival and ecosystem stability in inland arid and semi-arid areas. This study took Gansu Province, China, a typical area with complex terrain and variable climate, as the research subject. Based on Google Earth Engine, we used Landsat data and the Open-surface Water Detection Method with Enhanced Impurity Control method to monitor the spatiotemporal dynamics of surface water area in Gansu Province from 1985 to 2022, and quantitatively analyzed the main causes of regional differences in surface water area. The findings revealed that surface water area in Gansu Province expanded by 406.88 km2 from 1985 to 2022. Seasonal surface water area exhibited significant fluctuations, while permanent surface water area showed a steady increase. Notably, terrestrial water storage exhibited a trend of first decreasing and then increasing, correlated with the dynamics of surface water area. Climate change and human activities jointly affected surface hydrological processes, with the impact of climate change being slightly higher than that of human activities. Spatially, climate change affected the 'source' of surface water to a greater extent, while human activities tended to affect the 'destination' of surface water. Challenges of surface water resources faced by inland arid and semi-arid areas like Gansu Province are multifaceted. Therefore, we summarized the surface hydrology patterns typical in inland arid and semi-arid areas and tailored surface water 'supply-demand' balance strategies. The study not only sheds light on the dynamics of surface water area in Gansu Province, but also offers valuable insights for ecological protection and surface water resource management in inland arid and semi-arid areas facing water scarcity.
分类： 地球科学 >> 大气科学 提交时间： 2024-06-21 合作期刊: 《干旱区科学》
摘要： Vapor pressure deficit (VPD) plays a crucial role in determining plant physiological functions and exerts a substantial influence on vegetation, second only to carbon dioxide (CO2). As a robust indicator of atmospheric water demand, VPD has implications for global water resources, and its significance extends to the structure and functioning of ecosystems. However, the influence of VPD on vegetation growth under climate change remains unclear in China. This study employed empirical equations to estimate the VPD in China from 2000 to 2020 based on meteorological reanalysis data of the Climatic Research Unit (CRU) Time-Series version 4.06 (TS4.06) and European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis 5 (ERA-5). Vegetation growth status was characterized using three vegetation indices, namely gross primary productivity (GPP), leaf area index (LAI), and near-infrared reflectance of vegetation (NIRv). The spatiotemporal dynamics of VPD and vegetation indices were analyzed using the Theil-Sen median trend analysis and Mann-Kendall test. Furthermore, the influence of VPD on vegetation growth and its relative contribution were assessed using a multiple linear regression model. The results indicated an overall negative correlation between VPD and vegetation indices. Three VPD intervals for the correlations between VPD and vegetation indices were identified: a significant positive correlation at VPD below 4.820 hPa, a significant negative correlation at VPD within 4.820–9.000 hPa, and a notable weakening of negative correlation at VPD above 9.000 hPa. VPD exhibited a pronounced negative impact on vegetation growth, surpassing those of temperature, precipitation, and solar radiation in absolute magnitude. CO2 contributed most positively to vegetation growth, with VPD offsetting approximately 30.00% of the positive effect of CO2. As the rise of VPD decelerated, its relative contribution to vegetation growth diminished. Additionally, the intensification of spatial variations in temperature and precipitation accentuated the spatial heterogeneity in the impact of VPD on vegetation growth in China. This research provides a theoretical foundation for addressing climate change in China, especially regarding the challenges posed by increasing VPD
分类： 地球科学 >> 大气科学 提交时间： 2024-06-21 合作期刊: 《干旱区科学》
摘要： Methane (CH4) is a potent greenhouse gas that has a substantial impact on global warming due to its substantial influence on the greenhouse effect. Increasing extreme precipitation events, such as drought, attributable to global warming that caused by greenhouse gases, exert a profound impact on the intricate biological processes associated with CH4 uptake. Notably, the timing of extreme drought occurrence emerges as a pivotal factor influencing CH4 uptake, even when the degree of drought remains constant. However, it is still unclear how the growing season regulates the response of CH4 uptake to extreme drought. In an effort to bridge this knowledge gap, we conducted a field manipulative experiment to evaluate the impact of extreme drought on CH4 uptake during early, middle, and late growing stages in a temperate steppe of Inner Mongolia Autonomous Region, China. The result showed that all extreme drought consistently exerted positive effects on CH4 uptake regardless of seasonal timing. However, the magnitude of this effect varied depending on the timing of season, as evidenced by a stronger effect in early growing stage than in middle and late growing stages. Besides, the pathways of CH4 uptake were different from seasonal timing. Extreme drought affected soil physical-chemical properties and aboveground biomass (AGB), consequently leading to changes in CH4 uptake. The structural equation model showed that drought both in the early and middle growing stages enhanced CH4 uptake due to reduced soil water content (SWC), leading to a decrease in NO3–-N and an increase in pmoA abundance. However, drought in late growing stage primarily enhanced CH4 uptake only by decreasing SWC. Our results suggested that seasonal timing significantly contributed to regulate the impacts of extreme drought pathways and magnitudes on CH4 uptake. The findings can provide substantial implications for understanding how extreme droughts affect CH4 uptake and improve the prediction of potential ecological consequence under future climate change.
分类： 地球科学 >> 水文学 提交时间： 2024-06-21 合作期刊: 《干旱区科学》
摘要： Over the last three decades, more than half of the world's large lakes and wetlands have experienced significant shrinkage, primarily due to climate change and extensive water consumption for agriculture and other human needs. The desiccation of lakes leads to severe environmental, economic, and social repercussions. Urmia Lake, located in northwestern Iran and representing a vital natural ecosystem, has experienced a volume reduction of over 90.0%. Our research evaluated diverse water management strategies within the Urmia Lake basin and prospects of inter-basin water transfers. This study focused on strategies to safeguard the environmental water rights of the Urmia Lake by utilizing the modeling and simulating (MODSIM) model. The model simulated changes in the lake's water volume under various scenarios. These included diverting water from incoming rivers, cutting agricultural water use by 40.0%, releasing dam water in non-agricultural seasons, treated wastewater utilization, and inter-basin transfers. Analytical hierarchy process (AHP) was utilized to analyze the simulation results. Expert opinions with AHP analysis, acted as a multi-criteria decision-making tool to evaluate the simulation and determine the optimal water supply source priority for the Urmia Lake. Our findings underscore the critical importance of reducing agricultural water consumption as the foremost step in preserving the lake. Following this, inter-basin water transfers are suggested, with a detailed consideration of the inherent challenges and limitations faced by the source watersheds. It is imperative to conduct assessments on the impacts of these transfers on the downstream users and the potential environmental risks, advocating for a diplomatic and cooperative approach with adjacent country. This study also aims to forecast the volumes of water that can be transferred under different climatic conditions—drought, normal, and wet years—to inform strategic water management planning for the Urmia Lake. According to our projection, implementing the strategic scenarios outlined could significantly augment the lake's level and volume, potentially by 3.57×109–9.38×109 m3 over the coming 10 a and 3.57×109–10.70×109 m3 in the subsequent 15 a.
分类： 地球科学 >> 大气科学 提交时间： 2024-06-21 合作期刊: 《干旱区科学》
摘要： Stable water isotopes are natural tracers quantifying the contribution of moisture recycling to local precipitation, i.e., the moisture recycling ratio, but various isotope-based models usually lead to different results, which affects the accuracy of local moisture recycling. In this study, a total of 18 stations from four typical areas in China were selected to compare the performance of isotope-based linear and Bayesian mixing models and to determine local moisture recycling ratio. Among the three vapor sources including advection, transpiration, and surface evaporation, the advection vapor usually played a dominant role, and the contribution of surface evaporation was less than that of transpiration. When the abnormal values were ignored, the arithmetic averages of differences between isotope-based linear and the Bayesian mixing models were 0.9% for transpiration, 0.2% for surface evaporation, and –1.1% for advection, respectively, and the medians were 0.5%, 0.2%, and –0.8%, respectively. The importance of transpiration was slightly less for most cases when the Bayesian mixing model was applied, and the contribution of advection was relatively larger. The Bayesian mixing model was found to perform better in determining an efficient solution since linear model sometimes resulted in negative contribution ratios. Sensitivity test with two isotope scenarios indicated that the Bayesian model had a relatively low sensitivity to the changes in isotope input, and it was important to accurately estimate the isotopes in precipitation vapor. Generally, the Bayesian mixing model should be recommended instead of a linear model. The findings are useful for understanding the performance of isotope-based linear and Bayesian mixing models under various climate backgrounds.
分类： 计算机科学 >> 计算机应用技术 提交时间： 2024-06-21
摘要： 随着深度学习预训练语言模型（PLM）的发展，人们很快将其应用于科技文献的领域分类，所能达到的效果远远超过传统自然语言处理技术在相同任务中的表现。科技成果登记数据与科技文献有相似之处，都具有高度凝练的标题，有较为详细的长文本简介，可作为基于PLM分类方法的判断依据。同时科技成果又存在其独特之处，它的简介会介绍项目来源、项目背景、应用情况、获奖情况等多方面内容，而科技文献通常高度聚焦于研究内容。这一特殊性增加了基于PLM分类方法对科技成果中图分类做出正确预测的难度。本研究中，我们以预训练BERT模型（RoBERTa）为基础，构建了科技成果中图分类自动标引系统。受生成式大语言模型解码过程的启发引入了解码策略，将原本的分类问题转化为解码问题。该方法不仅提高了预测的准确率，同时解决了以往分类模型只能局限于单一级别执行预测的问题，从而实现了业务所需的动态预测。还可针对预测链上累积概率及终端概率等设置筛选条件，根据实际业务需求在可靠性和分类细致程度之间进行取舍。
分类： 护理学 >> 护理学 提交时间： 2024-06-20
摘要： 本文总结一例脑梗死患者早期给与康复训练的护理查房经验。由责任护士和主管医生介绍患者病情和治疗情况，由科内查房小组成员共同分析讨论现存的疑点难点，制定出相应的护理措施。通过中西医结合的护理模式帮助患者恢复自理能力，提高生活质量。
分类： 医学、药学 >> 预防医学与公共卫生学 提交时间： 2024-06-20 合作期刊: 《中国全科医学》
摘要： 背景全身炎症反应指数（SIRI）是一种较新的炎症生物标志物，其与缺血性脑卒中患者复发的关系尚不明确。目的 探讨SIRI水平与缺血性脑卒中患者1年内复发的关联性。方法 选取2019年3月—2021年3月在南昌大学第一附属医院、南昌大学第二附属医院、南昌市第二医院和南昌市第三医院住院且确诊为缺血性脑卒中的患者作为研究对象进入队列，并对其随访1年。收集入院后48h内的基线信息，随访过程中的缺血性脑卒中复发情况。采用Cox比例风险回归模型、限制性立方样条、亚组分析探讨SIRI与缺血性脑卒中患者1年内复发之间的关联性。结果 本研究纳入了1023例患者，在1年随访期间共107例（10.46%）复发。多因素Cox比例风险回归模型分析结果显示，在调整变量后，SIRI升高是缺血性脑卒中复发的危险因素（HR=1.06，95%CI=1.01~1.10）。将SIRI按四分位数分类时，Q4亚组（256例）与Q1亚组（256例）相比有较高的缺血性脑卒中复发风险（HR=1.80，95%CI=1.08~3.00）。限制性立方样条分析结果显示，SIRI与缺血性脑卒中复发风险呈J型的剂量-反应关系（P-Nonlinear=0.025）。进一步按性别、年龄、既往卒中、入院时美国国立卫生研究院卒中量表（NIHSS）评分分层进行亚组分析，结果显示，SIRI和入院时NIHSS评分分层存在交互作用（P<0.001），在NIHSS评分为0~1分时，SIRI（HR=1.25，95%CI=1.04~1.51，P=0.020）与卒中复发存在相关关系；在NIHSS评分为5~15分，SIRI（HR=1.20，95%CI=1.12~1.28，P<0.001）与卒中复发存在相关关系，表明在上述评分区间SIRI升高与缺血性脑卒中复发风险增加有关。结论 较高的SIRI与缺血性脑卒中复发风险增加明显相关。在SIRI与缺血性脑卒中复发之间观察到J形关联，且在NIHSS评分为0~1分、5~15分的缺血性脑卒中患者中，SIRI升高与缺血性脑卒中复发风险增加有关。
分类： 心理学 >> 管理心理学 提交时间： 2024-06-20
摘要： 次优食品是存在缺陷但可安全食用的食品，次优食品的商业化成为减少食物浪费的重要策略。然而，次优食品营销干预策略有效性的实验结果存在分歧。本研究通过元分析方法整合了目前次优食品营销干预策略的实证研究，分析了认知导向和情感导向营销干预策略对消费者次优食品评价和购买的有效性，并探索了营销干预策略有效性的边界条件。研究纳入符合要求的原始文献32篇(57个独立样本)，共94个效应量。结果发现，认知导向和情感导向营销干预策略能有效促进消费者对次优食品的积极评价和购买意愿，具有接近中等强度的有效性，且情感导向营销干预策略的效果优于认知导向营销干预策略。此外，次优食品特征、营销特征和顾客特征等因素调节次优食品营销干预策略的有效性。本研究发现为食品相关企业营销部门和政府部门提供了管理启示。
分类： 医学、药学 >> 预防医学与公共卫生学 提交时间： 2024-06-20 合作期刊: 《中国全科医学》
摘要： 背景学龄儿童的睡眠特征对其情绪和行为问题的产生有至关重要的影响，并且睡眠特征对学龄儿童执行功能的发展也起到了一定的作用，学龄儿童情绪和行为问题的产生与其执行功能的发展又有紧密的联系。目前对于学龄儿童睡眠特征、执行功能以及情绪和行为问题的关系是否存在中介效应的研究较少。目的 探讨学龄儿童的睡眠特征、执行功能与学龄儿童情绪和行为问题之间的关系，以及执行功能在学龄儿童的睡眠特征与情绪和行为问题中的中介作用。方法 于2021-08-21—10-08，采用方便取样法，选取河北省邯郸市涉县西戌小学与第四实验小学1~6年级学龄儿童516名，分别采用儿童睡眠习惯问卷（CSHQ）、长处与困难问卷（SDQ）以及执行功能行为评定量表（BRIEF）评定学龄儿童的睡眠特征、情绪和行为问题以及执行功能。利用SPSS27.0以及PROSCESSv4.1插件进行相关性分析、回归分析、中介的调节作用分析。结果 共发放问卷516份，回收有效问卷496份，有效回收率为96.1%。相关性分析结果显示，学龄儿童CSHQ总分与BRIEF中的行为管理指数、元认知功能指数抑制及转换、情感控制、任务启动、工作记忆、计划、组织、监控因子呈负相关（P0.05）。结论 学龄儿童睡眠特征、执行功能与其情绪和行为存着密切关系，且执行功能在儿童睡眠特征与学龄儿童的情绪和行为问题中存在完全中介作用。这一发现强调了良好睡眠对学龄儿童行为与情绪的重要性，并为提升学龄儿童执行功能和整体发展提供了新的视角和干预途径。
分类： 心理学 >> 心理学其他学科 提交时间： 2024-06-20
摘要： 心理与脑科学以人类被试作为研究对象，其结果的可推广性(generalizability, 也称为普适性)很大程度上取决于其样本的代表性(representativeness)。但心理学与脑科学研究中样本的代表性长久以来受到诟病。当前研究中主要存在两大问题：(1) 样本信息的缺失，大部分研究仅报告了被试的性别、年龄与国别，而被试的种族/民族、受教育程度和社会经济地位等重要信息较少被报告，且从时间上看，这种状况未出现根本性改变；(2) 从已报告的信息来看，当前样本的代表性不足：女性被试多于男生，集中于西方的、年轻的和受过高等教育的人群，而中老年人、受教育水平较低人群及低收入人群较少被研究者关注，亚洲人/亚裔、黑人/非洲裔、西班牙裔/拉丁裔人群同样较少受到关注，从国别角度来说，亚非拉国家尤其是非洲、拉丁美洲与中东地区的人群较少出现在心理学和脑科学研究中。以上两大问题的产生可能主要存在如下原因：方便取样法作为主要的取样方法；欧美研究者主导了心理学与脑科学的研究；整体上忽视文化以及不同人口因素的影响；研究者自身存有偏见。要改变这种现状，需要研究者、学术组织、期刊编辑和基金资助方等多方的共同努力。提升样本代表性将有助于让心理学与脑科学的科学知识应用于更广泛的群体，推动人类命运共同体的构建。
分类： 心理学 >> 认知心理学 提交时间： 2024-06-20
摘要： 自我影响注意分配的机制有待明确。三个实验采用双矩形提示范式，探讨与任务无关的自我关联信息如何影响空间及物体选择性注意加工。实验1发现，目标包含自我或朋友关联信息相比于目标包含生人关联信息，基于物体的注意效应减弱或消失，而基于空间的注意效应在三者间无显著差异。实验2在不同的学习情境下重复了实验1的发现，排除了情境熟悉性的影响。实验3使用抽象符号作为身份关联刺激，只在长反应时的被试群体上观察到自我关联信息调节物体选择性注意。分层漂移扩散模型的结果显示，自我关联信息通过刺激编码加工影响物体选择性注意。综上，自我关联加工调节物体而非空间选择性注意，该结果具有跨实验情境的一致性，提供了自我影响选择性注意的解释机制。
分类： 生物学 >> 植物学 >> 应用植物学 提交时间： 2024-06-20 合作期刊: 《广西植物》
摘要： 为探究海草床盐生植物根际土壤可培养细菌的新颖性和独特性及其代谢产物粗提物抑 菌活性，该文采集防城港市珍珠湾和渔洲坪海草床9 份盐生植物根际土壤进行研究，使用5 种 分离培养基，并采用稀释涂布法分离纯化可培养细菌。通过PCR 扩增和16S rRNA 测序进行菌 种鉴定并对其进行多样性分析。采用滤纸片法筛选可培养细菌发酵粗提物对耐甲氧西林金黄色 葡萄球菌（Methicillin-resistant Staphylococcus aureus）、表皮葡萄球菌（S. epidermidis）、金黄 色葡萄球菌（S. aureus）和鲍曼不动杆菌（Acinetobacter baumanii）4 种人类致病菌的抑制活性。 结果表明：（1）从9 份样品中共分离获得可培养细菌42 株，隶属13 个科14 个属，包括链霉 菌属、弧菌属、芽孢杆菌属、希瓦氏菌属、微杆菌属、短杆菌属、葡萄球菌属、鞘氨醇单胞菌 属、罗思氏菌属、嗜冷杆菌属、假诺卡氏菌属、发光菌属、氟单胞菌属和埃希氏菌属，其中链 霉菌属为优势菌属。（2）抑菌活性初筛结果显示6 株可培养细菌至少对2 种以上人类致病菌有 较强的抑制活性，其中1 株来自弧菌属，1 株来自罗思氏菌属，其余4 株均来自链霉菌属。综 上所述，防城港海域海草床盐生植物根际土壤微生物资源较新颖独特，链霉菌属细菌具有较强 的抑菌活性，为开发新型抗生素提供潜在菌种资源。
分类： 生物学 >> 植物学 >> 应用植物学 提交时间： 2024-06-20 合作期刊: 《广西植物》
摘要： 了解南亚热带中山常绿落叶阔叶混交林群落结构及物种多样性变化，可以为森林的合理管理与经 营提供科学依据。该文利用2015 和2022 年两轮调查的数据，运用α多样性指数、β多样性指数、主坐标分 析和空间点格局分析等方法，对岑王老山南亚热带中山常绿落叶阔叶混交林不同海拔上3 个1 hm2 群落的 木本植物的物种组成、物种多样性、胸径结构特征的变化以及树木死亡原因进行研究。结果表明：（1） 随着海拔升高，树木死亡率降低，树木死亡主要发生在小径级中，呈现非随机死亡模式且与活树密度无关。 （2）7 年间不同海拔群落的α多样性普遍减少，但不显著，α多样性指数变化率在不同海拔群落间相对一致。 各群落物种组成出现变化，但差异极小（P＞0.99），不同海拔群落间的物种组成有趋同趋势。（3）不同 海拔群落树木的平均胸径与总胸高断面积增加，径级结构呈现倒“J”型，群落有着良好的自我更新和维持 群落稳定的能力。综上所述，岑王老山南亚热带中山常绿落叶阔叶混交林的群落结构变化在不同海拔上总 体一致，群落结构稳定，未发生明显变化，各群落物种组成有趋同趋势；优势种的优势地位变化较小，稀 有种消亡导致物种丰富度下降。
分类： 生物学 >> 植物学 >> 应用植物学 提交时间： 2024-06-20 合作期刊: 《广西植物》
摘要： 为鉴定引起广西种植区白及锈病的病原菌种类并筛选抗锈病的白及资源，该文对 白及锈病病原菌进行了分离，利用形态学和分子生物学对病原菌进行了鉴定，同时通过人 工接种病原菌法对23 份白及进行了锈病抗性评价并筛选抗锈病白及资源。结果表明： （1）从白及感病叶片中分离的锈病病原菌X2 夏孢子呈金黄色，卵圆形或椭圆形， (21.43~30.95) μm × (13.10~19.05) μm ； 冬孢子呈橘红色、红褐色， 倒卵形或棍棒状， (17.25~30) μm × (5.5~6.65) μm。（2）把菌株X2 全长689 bp 的ITS 序列（OQ826009）与 GenBank 已登陆的序列进行相似性分析，发现与Coleosporium sp.（KY783686.1）匹配度 最高，序列一致性为95.86%；但与C. bletiae（MN108161.1，OP363678.1）聚为一类群。 结合形态学和分子生物学鉴定菌株X2 为C. bletiae。（3）人工接种菌株X2 14 d 后，23 份 白及材料病情指数范围在0~70.7 之间，根据病情指数划分为6 个不同的抗性等级：免疫的 材料1 份，病情指数为0；表现为高抗的材料4 份，病情指数为1.7~4.7；表现为抗病的材 料6 份，病情指数为5.6~9.4；表现为中抗的材料5 份，病情指数为12.7~18.3；表现为感 病的材料5 份，病情指数为32.0~49.1；表现为高感的材料2 份，病情指数为62.2~70.7。 表现免疫和高抗的5 份白及（分别来自云南红河、广西恭城和百色、贵州遵义和湖北宜 昌）病情指数低，抗锈病能力强，可推广应用或作为培育抗锈病优良种质的亲本材料。该 研究可为后续开展白及锈病的防治与致病机理研究提供支撑。
分类： 生物学 >> 植物学 >> 应用植物学 提交时间： 2024-06-20 合作期刊: 《广西植物》
摘要： 该文报道了广西西北部维管植物11 个新记录种，即红秆凤尾蕨(Pteris amoena Blume) 、川黔肠蕨 Diplaziopsis cavaleriana (Christ) C. Chr. 、南川短肠蕨 Diplazium nanchuanicum (W. M. Chu) Z. R. He 、树形针毛蕨 Macrothelypteris ornata (Wall. ex J. Sm.) Ching 、秦氏贯众(Cyrtomium chingianum P. S. Wang)、邢氏贯众(C. shingianum H. S. Kung et P. S. Wang)、变叶锥 Castanopsis diversifolia (Kurz) King ex Hook.f. 、粗穗柯 Lithocarpus elegans (Blume) Hatus. ex Soepadmo 、镰叶茜草(Rubia falciformis H. S. Lo)、高艾纳香 Blumea repanda (Roxb.) Hand.-Mazz. 、腺毛合耳菊 Synotis saluenensis (Diels) C. Jeffrey et Y. L. Chen ，这些新 记录种的发现为广西植物区系地理研究提供了新资料，对植物资源创新利用以及植物多样性 保护等具有重大意义。文中还提供了各种的主要形态特征描述、标本引证、彩色照片以及地 理分布等。
分类： 核科学技术 >> 核科学与技术 提交时间： 2024-06-20
摘要： 核动力装置在自然循环条件下蒸汽发生器内会发生单相倒流，单相倒流对自然循环流动阻力和蒸汽发生器传热能力都产生了很大影响。为了从具有普适性的角度研究蒸汽发生器二次侧水位对单相倒流的影响，本研究建立了无量纲守恒方程。基于无量纲守恒方程，采用微扰理论获得了考虑二次侧水位的单相倒流临界点理论模型，在分析了二次侧水位对倒U型管压降的基础上，进一步分析了不同管长、无量纲阻力数、无量纲传热数条件下二次侧水位对临界点的影响。本文研究结果表明：二次侧水位降低导致倒流发生临界点逐渐接近原点；不同管长条件下二次侧水位影响规律相同；随着水位的降低，无量纲阻力数、无量纲传热数条件下对临界点的影响逐渐减小。本研究结论从理论上证明了二次侧水位对单相倒流的影响不利于倒流的发生，从机理层面解释了原因，可以辅助相关核动力装置的事故分析。
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