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   5847篇
  免费   242篇
  国内免费   1篇
  2023年   22篇
  2022年   16篇
  2021年   44篇
  2020年   27篇
  2019年   45篇
  2018年   121篇
  2017年   100篇
  2016年   137篇
  2015年   102篇
  2014年   159篇
  2013年   265篇
  2012年   449篇
  2011年   645篇
  2010年   311篇
  2009年   91篇
  2008年   437篇
  2007年   395篇
  2006年   358篇
  2005年   314篇
  2004年   239篇
  2003年   242篇
  2002年   190篇
  2001年   80篇
  2000年   169篇
  1999年   93篇
  1998年   70篇
  1997年   24篇
  1996年   27篇
  1995年   26篇
  1994年   28篇
  1993年   23篇
  1992年   33篇
  1991年   33篇
  1989年   18篇
  1988年   17篇
  1987年   33篇
  1985年   31篇
  1984年   32篇
  1982年   30篇
  1981年   28篇
  1980年   31篇
  1979年   22篇
  1978年   24篇
  1977年   23篇
  1976年   37篇
  1975年   27篇
  1974年   31篇
  1973年   17篇
  1972年   20篇
  1971年   18篇
排序方式: 共有6090条查询结果,搜索用时 46 毫秒
1.
2.
3.
Polyclonal rabbit anti-bovine submaxillary mucin antibodies, anti-BSM IgG, were analyzed by autoradiography and densitometry (after SDS electrophoresis and blotting), ELISA, and IRMA assays for reactivity against native antigen BSM, deglycosylated and desialylated BSM, and human salivary and carcinoma-associated mucins. Known human tumor marker CA19-9 antigen reacted with rabbit anti-BSM IgG under different conditions, either soluble or immobilized. As soluble antigen, in IRMA it reacted with anti-BSM antibodies used both as a catcher and a tracer, as well as in combination with monoclonal anti-CA19-9 antibodies as a catcher. MUC1 mucin is a carrier of this carbohydrate antigen, CA19-9, or sialyl-Lewisa, as well as of CA15-3 antigen, a known breast tumor marker. Autoradiography and densitometry demonstrated binding of anti-BSM IgG to intact MUC1 in a sample of commercial standard preparation of CA19-9 antigen. The same method and analysis demonstrated binding of anti-BSM IgG to MUC1 and to smaller antigens of 85–120 kD in samples containing CA15-3 antigen: commercial standard preparation, human breast tissue, and human milk. In a sample of whole human saliva, reactions of both isoforms of MUC7 were detected by autoradiography, as bands of 85 and 115 kD, and densitogram analysis also demonstrated reaction with MUC5B. Chemical modifications performed as periodate oxidation and desialylation of the BSM demonstrated carbohydrate (i.e., sialic acid) epitope sensitivity for anti-BSM IgG. The results presented in this work indicate that polyclonal anti-BSM antibodies are specific for sialylated carbohydrate structure on mucins and could serve as a tool for investigation of human carcinoma-associated and salivary mucins.  相似文献   
4.
5.
ATP diphosphohydrolase activity and inorganic pyrophosphatase reached two maxima during cultivation of the low- and high-producing variant ofStreptomyces aureofaciens under conditions of phosphate limitation,i.e. after 30 and 70 h of cultivation. Increased levels of inorganic phosphate in a medium inhibitory to biosynthesis of chlortetracycline markedly decreased the levels of both enzymes. The ATP diphosphohydrolase activity was detected both in the supernatant and membrane fractions of the cell-free preparation of the mycelium.  相似文献   
6.
7.
8.
A mathematical model was developed for resolved temporal transients of experimentally recorded delayed fluorescence (DF) induction signal. During an intermittent light regime, antennas of the photosynthetic apparatus were treated as targets, repeatedly hit by potentially absorbable photons within a series of consecutive light flashes. Formulas were derived for the number of antennas, cumulatively hit by a specific number of photons, as a function of the flash serial number (time). Model parameters included number of absorbable photons in one flash, antenna sizes, and their number. A series of induction curves were analyzed, obtained from a Zea mays leaf segment and differing in the previous dark period (t d). Each curve, consisting of the two most prominent DF transients (C and D), was fitted with several model types, differing in the number of absorbed photons. For both transients, the best fitting result was achieved when DF induction was linked to the second absorbed photon. As expected, model parameters related to antenna sizes showed weaker dependence on t d than those referring to antenna number. With restrictions applied to this model, the two DF induction transients may be related to two classes of photosynthetic antennas. Their different sizes may have a predominant influence on the efficiency of photon absorption and possibly time-dependent appearance of DF transients. Published in Russian in Fiziologiya Rastenii, 2006, Vol. 53, No. 3, pp. 325–335. The text was submitted by the authors in English.  相似文献   
9.
Morphological data from two Iris pumila populations (measured on native clones, on their replants into the same habitat, and on their transplants into alternative habitat) were combined with native clones spatial position and spatial autocorrelations (SA) were calculated. Naturally growing I. pumila clones revealed significant SA that were positive on small distances and negative on medium ones in both open Hillock and shaded Woodland populations. No significant SA were detected when calculated with original clone positions, but with morphometric data from replants into the experimental plot in the same habitat. Some significant SA were, however, detected when morphometric data from transplants to alternative habitat were used. Detected SA on I. pumila clones were primarily a consequence of spatial structuring of environmental factors but also, in a lesser degree, a result of genetic spatial arrangements (most probably due to patterns of gene flow). The text was submitted by the authors in English.  相似文献   
10.
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