首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   23332篇
  免费   248篇
  国内免费   217篇
安全科学   751篇
废物处理   857篇
环保管理   3552篇
综合类   3786篇
基础理论   6014篇
环境理论   15篇
污染及防治   5837篇
评价与监测   1464篇
社会与环境   1377篇
灾害及防治   144篇
  2022年   184篇
  2021年   219篇
  2020年   164篇
  2019年   221篇
  2018年   332篇
  2017年   347篇
  2016年   532篇
  2015年   367篇
  2014年   562篇
  2013年   1963篇
  2012年   697篇
  2011年   966篇
  2010年   760篇
  2009年   804篇
  2008年   970篇
  2007年   1038篇
  2006年   896篇
  2005年   729篇
  2004年   793篇
  2003年   752篇
  2002年   686篇
  2001年   876篇
  2000年   622篇
  1999年   382篇
  1998年   325篇
  1997年   286篇
  1996年   301篇
  1995年   342篇
  1994年   357篇
  1993年   294篇
  1992年   319篇
  1991年   287篇
  1990年   322篇
  1989年   294篇
  1988年   255篇
  1987年   221篇
  1986年   206篇
  1985年   221篇
  1984年   242篇
  1983年   244篇
  1982年   253篇
  1981年   251篇
  1980年   184篇
  1979年   203篇
  1978年   172篇
  1977年   163篇
  1975年   147篇
  1974年   137篇
  1973年   134篇
  1972年   163篇
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
201.
Infrared observations with ground-based and balloon-borne telescopes are hampered by thermal background radiation and absorption caused by the earth's atmosphere. A sensitivity gain of up to three orders of magnitude can be obtained under the low photon background conditions of a helium-cooled space telescope. Physical properties of photodetectors and bolometers as well as their application to the new infrared telescopes aboard satellites and Spacelab are discussed.  相似文献   
202.
203.
204.
Pheromones — semiochemicals used by insects for intraspecific chemical communication — can be isolated and with special analytical techniques their chemical structure elucidated. With stereoselective synthesis methods, presented by the preparation of sex attractants and aggregating pheromones of moths and beetles, respectively, a synthetic access to compounds is given which can be used for behavior manipulation of insects. Aside the importance of these compounds for investigations of the sensoric process the possibility of their application in an integrated and biological pest control is discussed.  相似文献   
205.
206.
Research in molecular neurobiology has recently entered a new phase of rapid development as a result of the application of the techniques of molecular genetics. This is illustrated by recent work on the electric ray (Torpedo marmorata and T. californica), whose electric organ is a rich source of cholinergic synapses. Other examples from recent literature of the application of the recombinant DNA technique to the mammalian central nervous system are given and possible future developments are discussed.  相似文献   
207.
The female silkmoth Bombyx mori L. emits a second pheromone component bombykal (E-10, Z-12-hexade-cadien-1-al) in addition to the well-known sexual attractant bombykol (E-10, Z-12-hexadecadien-1-ol). Bombykal stimulates its own specialized and highly sensitive olfactory cells of the male moth. Surprisingly, the aldehyde inhibits the release of the male's wing-fluttering response to bombykol.  相似文献   
208.
209.
Mosaicism for the Wolf-Hirschhorn syndrome, del(4)(p16), is extremely rare and has not been reported in association with a numerical chromosome abnormality. We report the prenatal diagnosis of mosaic del(4)(p16) and non-mosaic trisomy 21 in a 16-week female fetus. The pregnancy ended in spontaneous abortion at 34 weeks secondary to fetal demise. The fetus had features of both 4p – and trisomy 21.  相似文献   
210.
Herlitz junctional epidermolysis bullosa (HJEB) is a severe blistering disorder which usually results in death during infancy. We have previously shown that the anchoring filament protein laminin-5 (kalinin/nicein), which mediates keratinocyte attachment and dermal–epidermal cohesion, is abnormally expressed in individuals with HJEB. Laminin-5 was detected by Western blot analysis in amniotic fluid from 44 consecutive normal secondtrimester control pregnancies, but was undetectable in second-trimester amniotic fluid from four pregnancies with fetuses affected by HJEB. In one case of severe non-Herlitz JEB, laminin-5 was detected in both amniotic fluid and skin. In human amniotic fluid, the laminin-5 a3 subunit was processed to a major 165 kD species and a minor 145 kD species and the β2 subunit was partially processed to 105 kD. Although laminin-5 was covalently associated with laminin-6 (K-laminin) in amniotic membrane, no covalent interaction was detected in amniotic fluid. Laminin-5 from amniotic fluid strongly supported keratinocyte attachment. These results suggest that Western blot analysis of second-trimester amniotic fluid is useful in determining the prenatal diagnosis of HJEB and that laminin-5 may serve a physiologically important function in amniotic fluid.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号