全文获取类型
收费全文 | 37518篇 |
免费 | 359篇 |
国内免费 | 241篇 |
专业分类
安全科学 | 889篇 |
废物处理 | 1572篇 |
环保管理 | 5122篇 |
综合类 | 5821篇 |
基础理论 | 10749篇 |
环境理论 | 14篇 |
污染及防治 | 9039篇 |
评价与监测 | 2385篇 |
社会与环境 | 2302篇 |
灾害及防治 | 225篇 |
出版年
2022年 | 217篇 |
2021年 | 241篇 |
2019年 | 251篇 |
2018年 | 881篇 |
2017年 | 854篇 |
2016年 | 1044篇 |
2015年 | 528篇 |
2014年 | 749篇 |
2013年 | 2587篇 |
2012年 | 1096篇 |
2011年 | 1889篇 |
2010年 | 1439篇 |
2009年 | 1446篇 |
2008年 | 1861篇 |
2007年 | 2070篇 |
2006年 | 1289篇 |
2005年 | 1131篇 |
2004年 | 1109篇 |
2003年 | 1110篇 |
2002年 | 1091篇 |
2001年 | 1289篇 |
2000年 | 920篇 |
1999年 | 553篇 |
1998年 | 456篇 |
1997年 | 437篇 |
1996年 | 452篇 |
1995年 | 519篇 |
1994年 | 512篇 |
1993年 | 447篇 |
1992年 | 466篇 |
1991年 | 443篇 |
1990年 | 482篇 |
1989年 | 462篇 |
1988年 | 403篇 |
1987年 | 375篇 |
1986年 | 338篇 |
1985年 | 329篇 |
1984年 | 407篇 |
1983年 | 358篇 |
1982年 | 403篇 |
1981年 | 362篇 |
1980年 | 294篇 |
1979年 | 323篇 |
1978年 | 281篇 |
1977年 | 234篇 |
1975年 | 229篇 |
1974年 | 250篇 |
1973年 | 239篇 |
1972年 | 247篇 |
1971年 | 214篇 |
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
341.
342.
343.
D. Spänkuch 《Die Naturwissenschaften》1991,78(8):347-354
The radiation budget of planets substantially determines their climates. For the terrestrial planets having their own imperceptible heat source compared to the solar radiation, the radiation budget supplies energy that can be transformed and used in their atmospheres and at their surfaces. The crucial role of the radiation budget for the Earth's climate is manifested in current international programs like the World Climate and Global Change Programs. The intercomparison and analysis of the radiation budget of the terrestrial planets, due to quite different atmospheric compositions and external conditions, provide a deeper insight into the relations of the different components of the radiation budget. 相似文献
344.
345.
346.
347.
Consensus on the evolutionary position of turtles within the amniote phylogeny has eluded evolutionary biologists for more than a century. This phylogenetic problem has remained unsolved partly because turtles have such a unique morphology that only few characters can be used to link them with any other group of amniotes. Among the many alternative hypotheses that have been postulated to explain the origin and phylogenetic relationships of turtles, a general agreement among paleontologists emerged in favoring the placement of turtles as the only living survivors of the anapsid reptiles (those that lack temporal fenestrae in the skull). However, recent morphological and molecular studies have radically changed our view of amniote phylogenetic relationships, and evidence is accumulating that supports the diapsid affinities of turtles. Molecular studies favor archosaurs (crocodiles and birds) as the living sister group of turtles, whereas morphological studies support lepidosaurs (tuatara, lizards, and snakes) as the closest living relatives of turtles. Accepting these hypotheses implies that turtles cannot be viewed any longer as primitive reptiles, and that they might have lost the temporal holes in the skull secondarily rather than never having had them. 相似文献
348.
This study investigated the influence of cat urine odour in suppressing development and fertility in Campbell's hamster males.
Exposure to this odour from postnatal day 11 until day 45 (sexual maturation) resulted in reduced sex organ weights, reduced
testosterone levels and in an increase in abnormalities of the synaptonemal complex in both sex chromosomes and autosomes.
Subsequent breeding experiments revealed a significant decrease in litter size. All these data indicate a severe effect of
predator odour on the breeding success of potential prey species. It is assumed that these effects are caused by the sulphurous
compounds in the urine; however, the underlying mechanisms are not yet known.
Received: 31 January 2000 / Accepted in revised form: 6 June 2000 相似文献
349.
350.