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71.
陕西佛坪国家级保护区是我国最重要的自然保护区之一,包括大熊猫、金丝猴在内的很多珍稀濒危物种分布其中。20世纪90年代后期,全国林业开始实施“天然林保护工程”,这对佛坪保护区当地的农业、工业、经济发展和生活质量产生了很大的影响。为了探究“天然林保护工程”对野生川金丝猴的保护产生何种影响,我们于2015年至2016年采用访问调查和实地踏查方法对佛坪保护区20世纪90年代至今的川金丝猴种群动态变化进行研究,结果发现不论是种群数量 (从少于500只增至671只左右) 还是栖息地面积 (从147.8 km2增至236.5 km2) 都明显增长; 家域范围随着年代的推移向低海拔位置扩大 (秋季平均海拔为1680m±304m),越来越靠近人类;川金丝猴在家域范围内,对常绿阔叶林和落叶阔叶林有明显的选择偏好,活动比例分别达到了40.11%和38.41%。实施“天然林保护工程”后,当地农业开发和经济活动在逐渐转型,减少了人类活动对野生动物栖息地的干扰,提升了栖息地保护的质量和生态环境。因此,此项工程的实施在该地区川金丝猴保护方面表现出积极的效果,促进了当地金丝猴栖息地的改善,种群数量得以增加扩大,是一个野生动物保护的成功案例。  相似文献   
72.
Vitamin E supplementation for the ruminant   总被引:5,自引:0,他引:5  
Vitamin E is essential for such body functions as growth, reproduction, prevention of various diseases, and for integrity of tissues. The most significantly important result of selenium and vitamin E deficiency is tissue degeneration (e.g. white muscle disease). Vitamin E does not cross the placenta in any appreciable amounts; however, it is concentrated in colostrum. Supplemental vitamin E can greatly increase colostral tocopherol. The importance of providing colostrum rich in vitamin E is essential as both calves and lambs are born with low levels of the vitamin. Vitamin E has been shown to increase performance of feedlot cattle and to increase immune response for ruminant health, including being beneficial for mastitis control. Vitamin E given to finishing cattle at higher than National Research Council (NRC) requirements dramatically maintained the red color (oxymyoglobin) compared with the oxidized metmyoglobin of beef. It appears that supplementation of 500 IU vitamin E per head daily for 84–126 days yields tissue -tocopherol that would maintain a favorable level of oxymyoglobin in meat, thus increasing its value. Vitamin E nutritional status is commonly estimated from plasma concentration, with a high correlation between plasma and liver levels of -tocopherol. The NRC estimates for vitamin E requirements of beef cattle, dairy cattle and sheep to range from 15 to 40 mg kg−1; however, higher levels will likely improve performance, and megadose levels will improve carcass quality.  相似文献   
73.
Temporal patterns of natural and sexual selection on male badge size and body traits were studied in a population of house sparrows, Passer domesticus. Badge size was a heritable trait as revealed by a significant father-son regression. Survival during autumn dispersal and winter was not related to badge size or body traits in yearling male house sparrows. Badges that signal dominance status were affected positively by directional selection for mating. Adult male house sparrows suffered an opposing selection pressure on badge size during autumn. Contrary to males, female house sparrows did not experience significant directional or stabilizing selection on any body trait. Directional sexual selection on male badge size due to female choice moves male sparrows away from their survival optimum. Opposing directional natural selection on badge size due to autumn mortality caused by predation maintains a stable badge size.  相似文献   
74.
在对武汉大学校园所在地武昌珞珈山全面踏勘的基础上,绘制了该区域的植被图,并将珞珈山植被划分为6植被型组10植被型20群系。通过对其中9个主要群落类型12个样地的样方调查,得到了有关群落结构的基本资料。结果表明,武昌珞珈山的植被性质为人工次生植被,其主体是小叶栎+樟林(面积18.187hm2)、火炬松+樟林(5.479hm2)、锐齿槲栎+槲栎林(2.711hm2)和水松+水杉+池杉林(2.410hm2),四者共占校园面积的21.45%。20群系中9个群系的建群种可自然更新。  相似文献   
75.
PurposeTo present an overview of the status of medical physics in radiotherapy in China, including facilities and devices, occupation, education, research, etc.Materials and methodsThe information about medical physics in clinics was obtained from the 9-th nationwide survey conducted by the China Society for Radiation Oncology in 2019. The data of medical physics in education and research was collected from the publications of the official and professional organizations.ResultsBy 2019, there were 1463 hospitals or institutes registered to practice radiotherapy and the number of accelerators per million population was 1.5. There were 4172 medical physicists working in clinics of radiation oncology. The ratio between the numbers of radiation oncologists and medical physicists is 3.51. Approximately, 95% of medical physicists have an undergraduate or graduate degrees in nuclear physics and biomedical engineering. 86% of medical physicists have certificates issued by the Chinese Society of Medical Physics. There has been a fast growth of publications by authors from mainland of China in the top international medical physics and radiotherapy journals since 2018.ConclusionsDemand for medical physicists in radiotherapy increased quickly in the past decade. The distribution of radiotherapy facilities in China became more balanced. High quality continuing education and training programs for medical physicists are deficient in most areas. The role of medical physicists in the clinic has not been clearly defined and their contributions have not been fully recognized by the community.  相似文献   
76.
People across many societies routinely participate in physical or intellectual competitions in the absence of immediate substantial monetary or other apparent material rewards. But increased fame and social status associated with awards, such as the “Oscars”, need not be necessarily and solely a cultural construct unrelated to natural selection. Rather, prizes might be badges of honor if they are also honest indicators of evolutionary fitness. Analyses of reported reproductive success data, from a survey of well-known female and male actors, followed previously reported patterns of biological fitness in this sample of a human population. In addition, the numbers of Academy Awards received for acting were positively associated with reported numbers of biological children for both genders. The association of increased fitness with more awards received was statistically consistent even when considering that this subset of the population conformed to the Bateman effect in human reproduction: male actors had a more positive correlation than females between cumulative numbers of married partners and overall numbers of children. Honest signals of reproductive quality that are displayed by both sexes are expected to occur in humans and other species with costly biparental care and mutual mate choice.  相似文献   
77.
Conspicuous consumption associated with status reinforcement behavior can be explained in terms of costly signaling, or strategic handicap theory, first articulated by Zahavi and later formalized by Grafen. A theory is introduced which suggests that the evolutionary raison d’être of status reinforcement behavior lies not only in its effects on lifetime reproductive success, but in its positive effects on the probability of survival through infrequent, unpredictable demographic bottlenecks. Under some circumstances, such “wasteful” displays may take the form of displays of altruistic behavior and generosity on the part of high status individuals, in that is signals the ability to bear the short-term costs of being generous or “cooperative,” while at the same time reinforcing the long-term benefits of higher status. James L. Boone is an associate professor in the Department of Anthropology at the University of New Mexico, where he carries out research in behavioral ecology and the archaeology of complex societies. His current interests are in the evolution of social status reinforcement behavior and variation in patterns of conspicuous consumption in human history.  相似文献   
78.
上海辰山植物园于2005年开始筹建,与此同时启动了的植物收集工作。本文就辰山植物园基本情况、植物收集中长远规划、进展及技术策略进行了论述。活植物收集和标本收集是辰山植物园植物收集工作的两个方面。活植物收集包括以华东植物区系植物为主的物种收集和以上海适生的观赏植物为主的园艺品种收集,如鸢尾属、绣球属、荚蓬属、锦带属和绣线菊属的舭赏园艺品种。截止到2010年,辰山植物园共收集了9000种和园艺品种。其中,华东植物区系物种有1700种,来自世界范围专业苗圃的园艺品种有2800个,另有4500种和品种是种植于温室的热带和亚热带植物。目前共收集了近10000份标本,多数为研究和活植物收集的凭证标本,全部存放于上海辰山植物园标本馆(CSH)。  相似文献   
79.
目的:探讨癫痫持续状态的发病危险因素。方法:对西京医院神经内科2000年1月至2009年11月连续登记住院的癫痫持续状态患者的临床资料进行回顾性分析,采用条件logistic回归方法筛选癫痫持续状态的危险因素。结果:共收集98例癫痫持续状态患者,一般情况显示:男性发病率明显高于女性,成人发病率明显高于儿童,CSE发生率明显高于NCSE;logistic回归结果显示:中枢神经系统感染(OR值为4.74)为SE的主要危险因素,其次为脑血管病(OR值为3.93)和颅脑外伤(OR值为1.84)。SE发作的有明显诱因的占19例,其中上呼吸道感染伴发热者比例较高。结论:中枢神经系统感染、脑血管病、脑外伤是癫痫持续状态最主要的危险因素,急性上呼吸道感染伴发热者最常见的诱因。预防感染、防治脑血管病、避免外伤,减少各种诱因是预防本病的关键。  相似文献   
80.
苗锐  康静  王莉  刘学东  邓艳春 《生物磁学》2011,(10):1881-1884
目的:探讨癫痫持续状态的发病危险因素。方法:对西京医院神经内科2000年1月至2009年11月连续登记住院的癫痫持续状态患者的临床资料进行回顾性分析,采用条件logistic回归方法筛选癫痫持续状态的危险因素。结果:共收集98例癫痫持续状态患者,一般情况显示:男性发病率明显高于女性,成人发病率明显高于儿童,CSE发生率明显高于NCSE;logistic回归结果显示:中枢神经系统感染(OR值为4.74)为SE的主要危险因素,其次为脑血管病(OR值为3.93)和颅脑外伤(OR值为1.84)。SE发作的有明显诱因的占19例,其中上呼吸道感染伴发热者比例较高。结论:中枢神经系统感染、脑血管病、脑外伤是癫痫持续状态最主要的危险因素,急性上呼吸道感染伴发热者最常见的诱因。预防感染、防治脑血管病、避免外伤,减少各种诱因是预防本病的关键。  相似文献   
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