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   71335篇
  免费   18769篇
  国内免费   3611篇
  93715篇
  2024年   89篇
  2023年   591篇
  2022年   1412篇
  2021年   2638篇
  2020年   3512篇
  2019年   5292篇
  2018年   5238篇
  2017年   5220篇
  2016年   5829篇
  2015年   6645篇
  2014年   6812篇
  2013年   7468篇
  2012年   5857篇
  2011年   5352篇
  2010年   5210篇
  2009年   3823篇
  2008年   3076篇
  2007年   2378篇
  2006年   2101篇
  2005年   1913篇
  2004年   1667篇
  2003年   1488篇
  2002年   1300篇
  2001年   1173篇
  2000年   990篇
  1999年   899篇
  1998年   478篇
  1997年   491篇
  1996年   472篇
  1995年   415篇
  1994年   398篇
  1993年   321篇
  1992年   459篇
  1991年   394篇
  1990年   338篇
  1989年   254篇
  1988年   240篇
  1987年   203篇
  1986年   144篇
  1985年   185篇
  1984年   122篇
  1983年   105篇
  1982年   82篇
  1981年   60篇
  1980年   55篇
  1979年   72篇
  1978年   66篇
  1977年   46篇
  1976年   48篇
  1973年   48篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
73.
74.
75.
M C Wu  M R Zaun  F M Wu 《FEBS letters》1989,244(2):338-342
Inhibitors of ADP-ribosylation inhibited the myeloid differentiation of murine myelomonocytic leukemia, WEHI-3BD+ cells induced by granulocyte colony-stimulating factor. Benzamide, at 2.0 mM, inhibited 50% of the WEHI-3BD+ cell differentiation but had no significant effect on the proliferation. However, benzylaminododecylguanine hydrochloride and p-methoxylbenzylaminodecamethylene guanidine sulfate at 2.0 and 2.2 microM, respectively, inhibited 50% of proliferation but had no effect at all on differentiation. The differential effects of inhibitors provide a model to study the role of ADP-ribosylation in myeloid differentiation.  相似文献   
76.
The addition of 0.167 to 4.0 mM cAMP to gel-filtered rabbit reticulocyte lysates stimulates the initial rate and the extent of polypeptide synthesis. The stimulation is at the initiation step of polypeptide synthesis as measured by the (i) increased dipeptide, methionyl-valine, accumulation in the presence of the specific initiation inhibitor, pactamycin, and (ii) increased formation of the 40 S and 80 S initiation complex when gel-filtered lysates are incubated with [35S]Met-tRNAFMet. Furthermore, a synergistic stimulation of protein synthesis is observed when cAMP and hexose phosphates (which alone elicit a 1.8-fold stimulation of protein synthesis) are added simultaneously to gel-filtered rabbit reticulocyte lysates. These results indicate that cAMP and hexose phosphates are both essential to maintain the high rate of initiation.  相似文献   
77.
78.
In this study, the first reported isolates of the genera Snowella and Woronichinia were characterized by 16S rRNA gene sequencing and morphological analysis. Phylogenetic studies and sequences for these genera were not available previously. By botanical criteria, the five isolated strains were identified as Snowella litoralis (Häyrén) Komárek et Hindák Snowella rosea (Snow) Elenkin and Woronichinia naegeliana (Unger) Elenkin. This study underlines the identification of freshly isolated cultures, since the Snowella strains lost the colony structure and were not identifiable after extended laboratory cultivation. In the 16S rRNA gene analysis, the Snowella strains formed a monophyletic cluster, which was most closely related to the Woronichinia strain. Thus, our results show that the morphology of the genera Snowella and Woronichinia was in congruence with their phylogeny, and their phylogeny seems to support the traditional botanical classification of these genera. Furthermore, the genera Snowella and Woronichinia occurred commonly and might occasionally be the most abundant cyanobacterial taxa in mainly oligotrophic and mesotrophic Finnish lakes. Woronichinia occurred frequently and also formed blooms in eutrophic Czech reservoirs.  相似文献   
79.
The chemiluminescence (CL) of bis(2,4,6‐trichlorophyenyl) oxalate with hydrogen peroxide in the present of cationic surfactant and gold nanoparticles was studied. The CL emission was obviously enhanced in the presence of surfactant at a suitable concentration, with a synergetic catalysis effect exhibited. Different sizes of gold nanoparticles (15 and 50 nm) showed different effects on CL intensity. Mechanisms of the CL reaction and sensitization effect are discussed. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
80.
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