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   536730篇
  免费   61106篇
  国内免费   1132篇
  2021年   4672篇
  2018年   6209篇
  2017年   5663篇
  2016年   8332篇
  2015年   12169篇
  2014年   13265篇
  2013年   18303篇
  2012年   21048篇
  2011年   20541篇
  2010年   13531篇
  2009年   12145篇
  2008年   17409篇
  2007年   17549篇
  2006年   16261篇
  2005年   15362篇
  2004年   15093篇
  2003年   14187篇
  2002年   13469篇
  2001年   23342篇
  2000年   23304篇
  1999年   18658篇
  1998年   6973篇
  1997年   7035篇
  1996年   6853篇
  1995年   6193篇
  1994年   6220篇
  1993年   5992篇
  1992年   14468篇
  1991年   13721篇
  1990年   13392篇
  1989年   13310篇
  1988年   11833篇
  1987年   11471篇
  1986年   10508篇
  1985年   10359篇
  1984年   8788篇
  1983年   7600篇
  1982年   5983篇
  1981年   5418篇
  1980年   5053篇
  1979年   8317篇
  1978年   6407篇
  1977年   5910篇
  1976年   5496篇
  1975年   5926篇
  1974年   6411篇
  1973年   6239篇
  1972年   5630篇
  1971年   5179篇
  1969年   4436篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
A formalin-fixed paraffin-embedded (FFPE) sample usually yields highly degraded DNA, which limits the use of techniques requiring high-quality DNA, such as Infinium Methylation microarrays. To overcome this restriction, we have applied an FFPE restoration procedure consisting of DNA repair and ligation processes in a set of paired fresh-frozen (FF) and FFPE samples. We validated the FFPE results in comparison with matched FF samples, enabling us to use FFPE samples on the Infinium HumanMethylation450 Methylation array.  相似文献   
92.
93.
94.
STACE, C. A. & JARVIS, C. E., 1985. TypiHcation of Linnaean taxa of annual Poaceae: Poeae related to Vulpia and Desmazeria. The status and typification of 15 Linnaean species of annual grasses related to Vulpia and Desmazeria are discussed. Of these 15, eight are represented by holotypes or lectotypes in LINN, two by lectotypes in Herb. A. van Royen (L), and one by a neotype in LINN. One (Festuca marina) is based on a pre-Linnaean polynomial and is represented by a lectotype in Herb. Sloane (BM); one (Cynosurus durus) has no known type specimens and we have chosen a Barrelier (1714) illustration as lectotype; one (Nardus aristatus) is an illegitimate name change for Nardus incurvus Gouan, for which we have selected a Scheuchzer (1719) illustration as lectotype; and finally Festuca incrassala appeared on a cancelled page of Species Plantarum and has no nomenclatural standing.  相似文献   
95.
96.
97.
98.
Chromatophores from Rhodopseudomonas capsulata cells grown semiaerobically in the dark oxidize NADH, succinate, and dichlorophenolindophenol. In the presence of N3? these activities are inhibited, but light induces oxidation of dichlorophenolindophenol with O2 as a terminal electron acceptor. Cyanide also inhibits electron transport but much higher concentrations are required to inhibit the photooxidation than the dark oxidation. The photooxidation was studied in a mutant strain of Rhodopseudomonas capsulata (YIV) which cannot grow anaerobically in the light, but similarly to the wild type, grows in the presence of oxygen. Chromatophores from YIV mutant catalyze photophosphorylation and dark oxidation activities with the same properties as those of the wild type. However, the rate of photooxidation in the mutant is only one-third that of the wild type. Based on the differential inhibitor sensitivity and on the mutation it is suggested that the photooxidase is different from the two respiratory oxidases and that this photooxidation activity might be essential for growth of the cells under anaerobic conditions in the light.  相似文献   
99.
100.
An apparatus for polyacrylamide slab gel electrophoresis is decribed which combines all parts into one integral unit. It eliminates several steps in the process of sealing, pouring, and setting the gels. Construction is easy with modest workshop facilities and the design easily adapted to suit most requirements. The apparatus provides a high degree of versatility and is suitable for use with many slab gel electrophoretic techniques.  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