全文获取类型
收费全文 | 814篇 |
免费 | 24篇 |
国内免费 | 70篇 |
专业分类
安全科学 | 45篇 |
废物处理 | 38篇 |
环保管理 | 76篇 |
综合类 | 235篇 |
基础理论 | 174篇 |
环境理论 | 4篇 |
污染及防治 | 235篇 |
评价与监测 | 41篇 |
社会与环境 | 50篇 |
灾害及防治 | 10篇 |
出版年
2024年 | 3篇 |
2023年 | 13篇 |
2022年 | 20篇 |
2021年 | 20篇 |
2020年 | 19篇 |
2019年 | 13篇 |
2018年 | 35篇 |
2017年 | 28篇 |
2016年 | 28篇 |
2015年 | 26篇 |
2014年 | 30篇 |
2013年 | 49篇 |
2012年 | 34篇 |
2011年 | 57篇 |
2010年 | 41篇 |
2009年 | 43篇 |
2008年 | 40篇 |
2007年 | 52篇 |
2006年 | 39篇 |
2005年 | 26篇 |
2004年 | 38篇 |
2003年 | 27篇 |
2002年 | 31篇 |
2001年 | 12篇 |
2000年 | 11篇 |
1999年 | 8篇 |
1998年 | 16篇 |
1997年 | 18篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 15篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1980年 | 3篇 |
1976年 | 3篇 |
1966年 | 3篇 |
1964年 | 3篇 |
1963年 | 3篇 |
1962年 | 2篇 |
1961年 | 3篇 |
1960年 | 3篇 |
1959年 | 2篇 |
1957年 | 5篇 |
1956年 | 6篇 |
1955年 | 4篇 |
1954年 | 2篇 |
1951年 | 3篇 |
1922年 | 3篇 |
排序方式: 共有908条查询结果,搜索用时 218 毫秒
571.
572.
573.
This study examines identity accumulation, others' acceptance of one's aspired self, work role salience, and job‐search self‐efficacy in relation to job stress. One hundred and eighty insurance agents working in six branches of an international assurance company completed self‐report questionnaires. Results indicate that identity accumulation and others' acceptance have direct, significant, and negative relationships with job stress. Job‐search self‐efficacy is found to be effective in moderating the relationship between work‐role salience and job stress. Implications and limitations of the study are discussed. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
574.
Andreas Schierling Konrad Dettner Jürgen Schmidt Karlheinz Seifert 《Die Naturwissenschaften》2012,99(8):665-669
To protect themselves from predation and microorganismic infestation, rove beetles of the genus Stenus produce and store bioactive alkaloids like stenusine, 3-(2-methyl-1-butenyl)pyridine, and cicindeloine in their pygidial glands. The biosynthesis of stenusine and 3-(2-methyl-1-butenyl)pyridine was previously investigated in Stenus bimaculatus and Stenus similis, respectively. Both molecules follow the same biosynthetic pathway, where the N-heterocyclic ring is derived from l-lysine and the side chain from l-isoleucine. The different alkaloids are finally obtained by slight modifications of shared precursor molecules. The piperideine alkaloid cicindeloine occurs as a main compound additionally to (E)-3-(2-methyl-1-butenyl)pyridine and traces of stenusine in the pygidial gland secretion of Stenus cicindeloides and Stenus solutus. Feeding of S. solutus beetles with [D,15N]-labeled amino acids followed by GC/MS analysis techniques showed that cicindeloine is synthesized via the identical pathway and precursor molecules as the other two defensive alkaloids. 相似文献
575.
Andreas P. Modlmeier Tobias Pamminger Susanne Foitzik Inon Scharf 《Die Naturwissenschaften》2012,99(10):811-819
Adjusting to low temperatures is important for animals living in cold environments. We studied the chill–coma recovery time in temperate ant workers (Temnothorax nylanderi) from colonies collected in autumn and spring in Germany. We experimentally acclimated these ant colonies to cold temperatures followed by warm temperatures. As expected, cold-acclimated workers recovered faster from freezing temperatures, but subsequent heat acclimation did not change the short recovery times observed after cold acclimation. Hence, either heat acclimation improves cold tolerance, possibly as a general response to stress, or at least it does not negate enhanced cold tolerance following cold acclimation. Colonies collected in spring showed similar cold tolerance levels to cold-acclimated colonies in the laboratory. Next, we compared the chill–coma recovery time of different worker castes and found that exterior workers recovered faster than interior workers. This difference may be related to their more frequent exposure to cold, higher activity level, or distinct physiology. Interior workers were also heavier and showed a higher gaster-to-head ratio and thorax ratio compared to exterior workers. An obvious difference between exterior and interior workers is activity level, but we found no link between activity and cold tolerance. This suggests that physiology rather than behavioral differences could cause the increased cold tolerance of exterior workers. Our study reveals the importance of acclimation for cold tolerance under natural and standardized conditions and demonstrates differences in cold tolerance and body dimensions in monomorphic behavioral castes of an ant. 相似文献
576.
577.
578.
579.