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   2153篇
  免费   214篇
  国内免费   1篇
  2368篇
  2022年   20篇
  2021年   35篇
  2020年   23篇
  2019年   31篇
  2018年   27篇
  2017年   34篇
  2016年   51篇
  2015年   79篇
  2014年   112篇
  2013年   108篇
  2012年   122篇
  2011年   147篇
  2010年   83篇
  2009年   82篇
  2008年   106篇
  2007年   97篇
  2006年   96篇
  2005年   82篇
  2004年   91篇
  2003年   82篇
  2002年   74篇
  2001年   34篇
  2000年   32篇
  1999年   35篇
  1998年   31篇
  1997年   25篇
  1996年   26篇
  1995年   17篇
  1994年   22篇
  1993年   15篇
  1992年   28篇
  1991年   24篇
  1990年   32篇
  1989年   29篇
  1988年   20篇
  1987年   20篇
  1985年   18篇
  1984年   14篇
  1983年   14篇
  1981年   35篇
  1980年   16篇
  1979年   14篇
  1978年   15篇
  1976年   20篇
  1975年   24篇
  1974年   21篇
  1973年   18篇
  1972年   22篇
  1971年   16篇
  1969年   12篇
排序方式: 共有2368条查询结果,搜索用时 15 毫秒
1.
2.
3.
Enzymes are remarkable molecules which make metabolism possible. Their processing powers are considerable for not only are they catalysts they also contribute to information processing, integration, coherence and memory in the cell. This complex of attributes suggests that a complementary perspective to enzyme nature and activity is needed related to what enzymes and verbs have in common. The value of this kind of thinking is that it shifts the focus from objects and mechanisms to processes and information. In order to support this idea a number of features which enzymes and verbs share are discussed including, context-dependence, occurrence, cases, voice, mood and glue/integrative capacities. The paper concludes with some reflections on the utility of a view of enzymes as verbs.  相似文献   
4.
5.
6.
Twenty-four of 63 enteric Gram-negative organisms (38.1%) which were isolated from 35 apparently healthy Nigerian students were found to have low trimethoprim resistance (MIC less than 1000 mg/l). These isolates were also found to be resistant to several other antibiotics and trimethoprim resistance was found to be transferable from 15 (62.5%) of the trimethoprim resistant organisms into E. coli EC 1005. It is likely that the high percentage of trimethoprim resistance encountered in this study is related to the high rate of resistance transfer which was observed.  相似文献   
7.
The NHS reforms have come to mean all things to all men (and women). Identifying a market oriented purchaser-provider split as the conceptual heart of the reforms is still, however, useful. There are important perverse incentives in and around the NHS that are associated with the reforms; furthermore, many reactions to the resulting problems are paradoxical and often counterproductive. Hitherto most criticism of the reforms from the health policy and management community (as opposed to the professions and the public) has been tactical rather than fundamental. There are serious problems for the NHS associated both with the NHS market and with current, often tacit, strategies for the future of the service.  相似文献   
8.
A soil isolate of Rhizobium leguminosarum bv. trifolii was marked with a lux CDABE gene cassette to enable the expression of bioluminescence. The suitability of the bacterium as a soil pollution biosensor was assessed using acute and chronic assays. Bacterial bioluminescence responded sensitively to the metals studied. The order of sensitivity was found to be Cd > Ni = Zn > Cu for the acute test and Cd > Ni = Zn = Cu for the chronic test. The sensitive response of the biosensor highlighted its potential for use as an indicator of soil pollution.  相似文献   
9.
10.
The reversible inhibition of respiratory activity could provide a novel approach to the preservation of traditionally hard to store plant germplasm such as clonal materials and recalcitrant seed. The gaseous anesthetic nitrous oxide caused a reversible, dose-dependent, partial inhibition of dioxygen utilization in mitochondrial particles isolated from cell suspension cultures of the salt-tolerant marsh grass Distichlis spicata, with maximal inhibition of 33% after 30 minutes exposure to an atmosphere of 80% nitrous oxide plus 20% oxygen. Respiration of whole cells required longer time to be affected by the anesthetic, and was reversibly inhibited an average of 19% when measured using a differential respirometer. Exposure to 80% nitrous oxide plus 20% oxygen for up to 10 days caused no measurable effect on cell growth.Abbreviations PCV packed cell volume - EDTA sodium ethylenediaminetetraacetic acid - BSA bovine serum albumin - MOPS 3(N-morpholino) propanesulfonic acid - TMPD N,N,N',N'-tetramethyl-p-phenylene diamine - STP standard temperature and pressure  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