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   456072篇
  免费   56437篇
  国内免费   281篇
  2018年   3940篇
  2017年   3619篇
  2016年   5619篇
  2015年   8474篇
  2014年   9457篇
  2013年   13274篇
  2012年   15382篇
  2011年   15446篇
  2010年   10204篇
  2009年   9447篇
  2008年   13425篇
  2007年   13915篇
  2006年   12615篇
  2005年   12385篇
  2004年   12155篇
  2003年   11549篇
  2002年   11015篇
  2001年   21723篇
  2000年   21870篇
  1999年   17482篇
  1998年   6304篇
  1997年   6526篇
  1996年   6350篇
  1995年   5746篇
  1994年   5792篇
  1993年   5624篇
  1992年   13727篇
  1991年   13013篇
  1990年   12709篇
  1989年   12559篇
  1988年   11222篇
  1987年   10850篇
  1986年   9924篇
  1985年   9697篇
  1984年   8242篇
  1983年   7112篇
  1982年   5567篇
  1981年   5041篇
  1980年   4680篇
  1979年   7725篇
  1978年   5940篇
  1977年   5455篇
  1976年   5101篇
  1975年   5398篇
  1974年   5850篇
  1973年   5691篇
  1972年   5127篇
  1971年   4754篇
  1970年   3941篇
  1969年   3874篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
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   
82.
83.
84.
85.
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   
86.
87.
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   
88.
89.
Conditions for breaking various medically important yeasts using glass beads, 30 ml Corex centrifuge tubes, and a Vortex mixer were determined. From 75–95% ofCandida hyphal cells and all species of yeasts exceptSporothrix schenckii were broken when 10 g of 0.45–0.50 mm glass beads, 50–300 mg of wet cells in 5 ml of buffer, and 90 s of vortexing were employed. Yeasts ofSporothrix schenckii broke more efficiently when 0.25–0.30 mm beads were used.  相似文献   
90.
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