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   4994篇
  免费   34篇
  国内免费   27篇
安全科学   52篇
废物处理   193篇
环保管理   185篇
综合类   2094篇
基础理论   914篇
环境理论   5篇
污染及防治   1098篇
评价与监测   315篇
社会与环境   183篇
灾害及防治   16篇
  2023年   35篇
  2022年   79篇
  2021年   55篇
  2020年   38篇
  2019年   43篇
  2018年   95篇
  2017年   82篇
  2016年   120篇
  2015年   75篇
  2014年   154篇
  2013年   247篇
  2012年   156篇
  2011年   156篇
  2010年   149篇
  2009年   154篇
  2008年   185篇
  2007年   204篇
  2006年   151篇
  2005年   126篇
  2004年   114篇
  2003年   132篇
  2002年   101篇
  2001年   92篇
  2000年   85篇
  1999年   84篇
  1998年   64篇
  1997年   55篇
  1996年   37篇
  1995年   53篇
  1994年   57篇
  1991年   37篇
  1990年   43篇
  1989年   36篇
  1985年   35篇
  1979年   39篇
  1969年   35篇
  1967年   56篇
  1966年   48篇
  1965年   56篇
  1964年   64篇
  1963年   66篇
  1962年   59篇
  1961年   67篇
  1960年   60篇
  1959年   66篇
  1958年   61篇
  1957年   72篇
  1956年   49篇
  1955年   49篇
  1954年   46篇
排序方式: 共有5055条查询结果,搜索用时 218 毫秒
161.
In this study, an inventory of air pollutant emission estimates from major air polluting sources in Turkey for period between 1985 and 2005 with 5-year intervals were estimated. Inventory covers anthropogenic sources of five major air pollutants of particulate matter, sulfur dioxide, carbon monoxide, nitrogen oxides and non-methane volatile organic compounds. Their break-down with respect to main activity sectors were shown and their distribution by the largest industrial source categories were worked out as annual estimates. This inventory and its analysis point to serious environmental implications of air pollutants and a need to develop a policy plan for reducing these emissions.  相似文献   
162.
2+   concentrations tropomyosin is located at the edge of the thin filament, thereby interfering with the formation of strong actin-myosin linkages (blocked state). An increase in Ca2+ activity causes an azimuthal shift of tropomyosin around the filament (by about 30°), thereby increasing the probability of low-force crossbridge interaction, a process which by cooperative effects induces further tropomyosin movement (by an additional 10°) which results in the open state of the filament characterized by forceful crossbridge interaction. (This mechanism may be analogous to that in ligand-gated ion channels, where ligand binding increases the open probability of the pore.) The extent of activation then depends on the free Ca2+ concentration and on the calcium sensitivity of the thin filament that may be affected by protein phosphorylation, crossbridge attachment, the troponin isoform composition of the filament, and novel calcium-sensitizing drugs that act on the contractile or regulatory proteins and thus increase the force of the heart.  相似文献   
163.
164.
165.
 Common blue butterflies (Polyommatus icarus) sequester flavonoids from their larval host plants and allocate these UV-absorbing pigments to the wings. In field experiments using dummies constructed from female butterflies, mate-searching males inspected flavonoid-rich dummies more intensively than those with little or no flavonoids. Flavonoid content as signalled by UV-wing pattern may indicate ontogenetically determined female quality or enhance detectability to males. Received: 21 March 2000 / Accepted in revised form: 17 May 2000  相似文献   
166.
167.
Intergeneric transmission of a marine plant DNA virus   总被引:1,自引:0,他引:1  
  相似文献   
168.
169.
170.
Microorganisms have been being released into the environment for a long time, e.g., in agriculture or for biotechnological processes. Amongst these microorganisms were some that had been labeled genetically, or improved by selection. In recent years, efforts have been directed towards alteration or optimization of appropriate bacteria and viruses by methods of recombinant DNA technology. In some cases, first releases of such organisms have been undertaken in experimental plots. There is public concern about the environmental risks of such releases, and about possible adverse effects. The present status of research in this controversial field, the regulations available in Germany and the United States, as well as the prospects of such work for the future are presented.  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