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   2618篇
  免费   168篇
  2786篇
  2022年   15篇
  2021年   24篇
  2017年   17篇
  2016年   32篇
  2015年   60篇
  2014年   67篇
  2013年   116篇
  2012年   113篇
  2011年   117篇
  2010年   60篇
  2009年   65篇
  2008年   138篇
  2007年   139篇
  2006年   116篇
  2005年   133篇
  2004年   151篇
  2003年   133篇
  2002年   100篇
  2001年   92篇
  2000年   77篇
  1999年   65篇
  1998年   38篇
  1997年   37篇
  1996年   21篇
  1995年   18篇
  1994年   21篇
  1993年   24篇
  1992年   75篇
  1991年   49篇
  1990年   50篇
  1989年   70篇
  1988年   59篇
  1987年   45篇
  1986年   34篇
  1985年   40篇
  1984年   21篇
  1983年   16篇
  1982年   19篇
  1981年   19篇
  1980年   17篇
  1979年   18篇
  1978年   17篇
  1977年   14篇
  1974年   16篇
  1973年   22篇
  1971年   16篇
  1970年   18篇
  1968年   17篇
  1967年   21篇
  1966年   20篇
排序方式: 共有2786条查询结果,搜索用时 9 毫秒
1.
1. A phylogenetic study of oxytocin (OXT)-like immunoreactive cells was performed by the PAP method in the central nervous system of invertebrates. 2. The immunoreactivity was detected in the nerve cells of Hydra magnipapillata of the Coelenterata; Neanthes japonica and Pheretima communissima of the Annelida; Oncidium verrucosum, Limax marginatus and Meretrix lamarckii of the Mollusca; and Baratha brassica of the Arthropoda. 3. No immunoreactive cells were found in Bipalium sp. of the Platyhelminthes; Pomacea canaliculata, Aplysia kurodai, Bradybaena similaris and Achatina fulica of the Mollusca; and Gnorimosphaeroma rayi, Procambarus clarkii, Hemigrapsus sanguineus, Helice tridens and Gryllus bimaculatus of the Arthropoda; Asterina pectinifera of the Echinodermata; and Halocynthia roretzi of the Protochordata. 4. These results demonstrate that an OXT-immunoreactive substance is widely present not only in vertebrates but also in invertebrates. 5. OXT seems to have been introduced into these invertebrates at an early stage of their phylogenetic history.  相似文献   
2.
1. Stomachs of adult teleosts and elasmobranchs reacted to an anti-embryonic chicken pepsinogen antiserum (anti-ECPg) as well as to an anti-adult chicken pepsinogen antiserum (anti-ACPg). 2. Zymograms and immunoblots of stomach extracts revealed that anti-ECPg- and anti-ACPg-reactive substances possess peptic activity. 3. The possible relationship between anti-ECPg-reactive pepsinogens in fish and prochymosins in higher vertebrates is discussed.  相似文献   
3.
Numerical taxonomy of Mycobacterium fortuitum   总被引:1,自引:0,他引:1  
  相似文献   
4.
5.
6.
7.
8.
Mizuno  N.  Yoshida  H. 《Plant and Soil》1993,155(1):505-508
The severity of the incidence of the fungal disease, potato scab, varies with different soil groups at the same soil pH. At a soil pH of 5.3, potato scab is easily controlled in soils of western Hokkaido (soil group A) by simply decreasing soil pH, but in soils from eastern Hokkaido (soil group B) it is not so easily controlled. The difference appears to be due to higher levels and exchangeable aluminium in Group A.Addition of sufficient aluminium or ferrous sulfate to a group B soil decreased the incidence of potato scab in a field experiment. Higher levels of aluminium sulfate depressed crop production. It is concluded that aluminium ions control the incidence of potato scab in acid soils. It is suggested that, in soils with low exchange acidity Y1, potato scab can be controlled by adding sufficient aluminium to increase their exchange acidity Y1 to above 7–8.  相似文献   
9.
The proteins KdpD and KdpE are crucial to the osmotic regulation of the kdpABC operon that is responsible for the high-affinity K+ ion transport system in Escherichia coli. We demonstrated previously that the response regulator, KdpE, is capable of undergoing Phosphorylation mediated by the sensory protein kinase, KdpD. In this study, we obtained biochemical evidence supporting the view that when KdpE is phosphorylated, it takes on an active form that exhibits relatively high affinity for the kdpABC promoter, which in turn results in activation of the kdpABC operon. It was also suggested that the central hydrophobic domain of KdpD, which is conceivably responsible for membrane anchoring of this protein, plays a role in the signalling mechanism underlying KdpE Phosphorylation in response to hyperosmotic stress.  相似文献   
10.
A Kuroiwa  D Mizuno  S Natori 《Biochemistry》1977,16(26):5687-5691
When partially purified Ehrlich ascites tumor RNA polymerase II was further purified on a column of phosphocellulose, stimulation of its catalysis of RNA synthesis by stimulatory factor S-II was greatly decreased. This decrease in sensitivity to the stimulatory factor was reversible: the enzyme eluted from phosphocellulose became sensitive to the factor when mixed with a protein fraction eluted from the phosphocellulose at high salt concentration. Evidence was obtained that this protein, named helper protein, binds, to the enzyme eluted from phosphocellulose, causing it to recover sensitivity to stimulatory factor S-II.  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