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   1744篇
  免费   130篇
  国内免费   1篇
  2023年   9篇
  2021年   29篇
  2020年   23篇
  2019年   24篇
  2018年   32篇
  2017年   35篇
  2016年   31篇
  2015年   54篇
  2014年   77篇
  2013年   89篇
  2012年   105篇
  2011年   105篇
  2010年   71篇
  2009年   63篇
  2008年   92篇
  2007年   92篇
  2006年   72篇
  2005年   66篇
  2004年   68篇
  2003年   55篇
  2002年   65篇
  2001年   53篇
  2000年   68篇
  1999年   54篇
  1998年   25篇
  1997年   16篇
  1996年   14篇
  1995年   9篇
  1994年   17篇
  1993年   17篇
  1992年   29篇
  1991年   33篇
  1990年   32篇
  1989年   32篇
  1988年   22篇
  1987年   17篇
  1986年   12篇
  1985年   12篇
  1984年   13篇
  1983年   8篇
  1982年   15篇
  1980年   7篇
  1979年   11篇
  1977年   11篇
  1976年   7篇
  1975年   7篇
  1974年   13篇
  1973年   9篇
  1971年   9篇
  1966年   5篇
排序方式: 共有1875条查询结果,搜索用时 15 毫秒
61.
Membranes from mammary glands of mildly hypothyroid mice show a 70–85% reduction in prolactin binding while those from hyperthyroid mice bound 66% more prolactin compared to similar preparations from euthyroid animals. The prolactin binding data for mammary glands correlate well with the ability of the tissue from animals in various thyroid states to respond to prolactin invitro with increased lactose synthetase activity. Binding of prolactin to mammary membranes is enhanced when explants from mid-pregnant mice are cultured overnight in the presence of insulin, hydrocortisone and 10?9 M L-T3. This enhancement is not blocked by puromycin. These data suggest that thyroid hormones control the level of prolactin binding in mouse mammary tissue. This may be accomplished, at least in part, by activation of preexisting receptor molecules.  相似文献   
62.
63.
Summary Hyphae of M. phaseoli failed to grow on unsterilized natural soil and were completely lysed within 4 days of exposure. Germination of sclerotia in natural soil was inhibited indicating soil fungistasis. Lysis of mycelium and inhibition of germination of sclerotia could be annulled by addition of various organic nutrients and fertilizers to natural soil or by autoclaving the soil. Germination of dormant sclerotia in natural soil was stimulated by root-exudates of host and non-host plants. Population of sclerotia buried in unsterilized natural soil gradually declined and after 15 months only 35 per cent of the initial number could be recovered; more than 80 per cent of these germinated when nutrients were added. Data suggest poor saprophytic ability of M. phaseoli in mycelial form and the involvement of dormant sclerotia in the survival of the organism in soil.  相似文献   
64.
Exogenously supplied ribose and deoxyribose in a medium containingsucrose+ IAA considerably enhanced the formation of roots onhypocotyl cuttings of Phaseolus mungo with intact apex andleaves.The effect increased with increasing concentration of pentosesugars and was more pronounced with deoxyribose than with ribosesugar. (Received October 25, 1975; )  相似文献   
65.
66.
Elevated intraocular pressure (IOP) is a risk factor in glaucoma, a group of irreversible blinding diseases. Endogenous lipids may be involved in regulation of IOP homeostasis. We present comparative fold analysis of phospholipids and sphingolipids of aqueous humour and trabecular meshwork from human control vs primary open-angle glaucoma and mouse control (normotensive) vs ocular hypertensive state. The fold analysis in control vs disease state was based on ratiometric mass spectrometric data for above classes of lipids. We standardized in vitro assays for rapid characterization of lipids undergoing significant diminishment in disease state. Evaluation of lipids using in vitro assays helped select a finite number of lipids that may potentially expand cellular interstitial space embedded in an artificial matrix or increase fluid flow across a layer of cells. These assays reduced a number of lipids for initial evaluation using a mouse model, DBA/2J with spontaneous IOP elevation. These lipids were then used in other mouse models for confirmation of IOP lowering potential of a few lipids that were found promising in previous assessments. Our results provide selected lipid molecules that can be pursued for further evaluation and studies that may provide insight into their function.  相似文献   
67.
68.
Study of genetic diversity in crop plants is essential for the selection of appropriate germplasm for crop improvement. As salinity posses a serious environmental challenge to rice production globally and especially in India, it is imperative that the study of large collections of germplasms be undertaken to search for salt tolerant stocks. In the present study, 64 indica germplasms were collected from different agro-climatic zones of West Bengal, India, from the Himalayan foothills in the northern part down to the southern saline belt of the state keeping in view the soil characteristics and other edaphic factors prevailing in the region. Salt tolerance parameters were used to screen the large set of germplasms in terms of root-shoot length, fresh-dry weight, chlorophyll content, Na+/K+ ratio and germination potential in presence of salt. Standard evaluation score or SES was calculated to find out tolerant to sensitive cultivar. Twenty-one SSR markers, some associated with the Saltol QTL and others being candidate gene based SSR (cgSSR) were used to study the polymorphism of collected germplasm. A wide diversity was detected among the collected germplasms at the phenotypic as well as molecular level. Of the 21 SSR markers, 15 markers were found to be polymorphic with 88 alleles. Based on phenotypic and biochemical results, 21 genotypes were identified as salinity tolerant, whereas 40 genotypes turned out to be salt susceptible. The present study shows that apart from the established salt tolerant lines, several other landraces like Bonkanta, Morisal, Ghiosh, Patni may be the source of salt tolerant donor in future breeding programs.  相似文献   
69.
Molecular Biology Reports - Globally, breast cancer is a serious concern that exhibits a persistent rise in its incidence and related mortality even after significant advancement in the field of...  相似文献   
70.
Abstract

A convenient synthesis of 1-(2-deoxy-β-D-erythro-pentofuranosyl)quinazoline-2,4(3H)-dione ( 6 ) has been accomplished. The structural conformation of ( 6 ) was derived by 2D NMR, COSY and NOESY experiments. Nucleoside ( 6 ) was incorporated into G-rich triplex forming oligonucleotides (TFOs) by solid-support, phosphoramidite method. The triplex forming capabilities of modified TFOs (S2, S3 and S4) has been evaluated in antiparallel motif with a target duplex (duplex-31) 5′d(GTCACTGGCCCTTCCTCCTTCCCGGTCTCAG)3′-5′d(CAGTGACCGGGAAGGAGGAAGGGCCAGAGT)3′ (D1) at pH 7.6. The parallel triplex formation of a shorter TFO (S6) containing Q has also been studied with a target duplex-11 (D2) at pH 5.0.  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