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   885篇
  免费   47篇
  国内免费   1篇
  933篇
  2024年   1篇
  2023年   4篇
  2022年   14篇
  2021年   27篇
  2020年   12篇
  2019年   20篇
  2018年   25篇
  2017年   17篇
  2016年   52篇
  2015年   54篇
  2014年   56篇
  2013年   72篇
  2012年   82篇
  2011年   83篇
  2010年   41篇
  2009年   40篇
  2008年   63篇
  2007年   51篇
  2006年   52篇
  2005年   34篇
  2004年   34篇
  2003年   18篇
  2002年   23篇
  2001年   2篇
  2000年   3篇
  1999年   5篇
  1998年   5篇
  1997年   4篇
  1996年   3篇
  1995年   1篇
  1994年   2篇
  1991年   4篇
  1990年   1篇
  1989年   1篇
  1988年   2篇
  1985年   1篇
  1982年   1篇
  1981年   2篇
  1979年   2篇
  1978年   4篇
  1977年   2篇
  1976年   1篇
  1975年   1篇
  1974年   2篇
  1973年   1篇
  1971年   2篇
  1970年   3篇
  1969年   2篇
  1966年   1篇
排序方式: 共有933条查询结果,搜索用时 15 毫秒
921.
Neuropeptide Y (NPY) is one of the most potent stimulants of food intake in vertebrates, mammals and fish. However, the present knowledge about feeding behaviour in fish is still limited and based on studies in a few species. The Brazilian flounder Paralichthys orbignyanus is being considered for aquaculture, and it is important to understand the mechanisms regulating feeding in order to improve its performance in captivity. The objectives of this study were to clone NPY cDNA, evaluate the mRNA levels in different tissues of flounder, and also evaluate brain NPY expression to associate food intake with NPY expression levels. A 597 bp NPY cDNA was cloned from Brazilian flounder brain. NPY expression was detected in all the peripheral tissues analysed. No significant differences were observed in brain NPY gene expression over 24 h after food intake at a temperature of 15 ± 3°C. No correlation was observed among plasma glucose, total protein, cholesterol, triglycerides and NPY expression levels during this 24 h period. On the other hand, mRNA levels were increased after two weeks of fasting at elevated temperatures. Our results suggest that NPY mRNA levels in Brazilian flounder are affected by temperature.  相似文献   
922.
923.
924.
925.
926.
927.
Influenza is one of the main plagues worldwide. The statistical likelihood of a new pandemic outbreak, together with the alarming emergence of influenza virus strains that are resistant to available antiviral medications, highlights the need for new antiviral drugs. Lactoferrin, a 80 kDa bi-globular iron-binding glycoprotein, is a pleiotropic factor with potent antimicrobial and immunomodulatory activities. Although the antiviral effect of lactoferrin is one of its major biological functions, the mechanism of action is still under debate. In this research, we have analyzed the effect of bovine lactoferrin (bLf) on Influenza A virus infection in vitro. Our results showed that (i) Influenza virus infected cells died as a result of apoptosis, (ii) bLf treatment inhibited programmed cell death by interfering with function of caspase 3, a major virus-induced apoptosis effector, and (iii) bLf efficiently blocked nuclear export of viral ribonucleoproteins so preventing viral assembly. These results provide further insights on the antiviral activity of bLf and suggest novel strategies for treatment of Influenza virus infection.  相似文献   
928.
Spontaneous Raman micro‐spectroscopy has been demonstrated great potential in delineating tumor margins; however, it is limited by slow acquisition speed. We describe a superpixel acquisition approach that can expedite acquisition between ~×100 and ×10 000, as compared to point‐by‐point scanning by trading off spatial resolution. We present the first demonstration of superpixel acquisition on rapid discrimination of basal cell carcinoma tumor from eight patients undergoing Mohs micrographic surgery. Results have been demonstrated high discriminant power for tumor vs normal skin based on the biochemical differences between nucleus, collagen, keratin and ceramide. We further perform raster‐scanned superpixel Raman imaging on positive and negative margin samples. Our results indicate superpixel acquisition can facilitate the use of Raman microspectroscopy as a rapid and specific tool for tumor margin assessment.  相似文献   
929.
Formamide NH2CHO chemistry provides a unitary frame into which several pieces of the origin-of-life puzzle may be adjusted. Synthetic processes were uncovered which, starting from formamide and prebiotically easily available common catalysts, yield all the necessary nucleic bases precursors, including acyclonucleosides. Formamide allows phosphorylations and trans-phosphorylations, favours the micellar aggregation of surfactants and, most importantly, determines conditions in which the formation of nucleic polymers is thermodynamically favoured. In the detected conditions, the phosphoester bonds are more stable in the polymeric than in the monomeric form, thus allowing formation and survival of informational nucleic polymers. Presented at: National Workshop on Astrobiology: Search for Life in the Solar System, Capri, Italy, 26 to 28 October, 2005.  相似文献   
930.

Background  

Bacteriophage Φ12 is a member of the Cystoviridae and is distinct from Φ6, the first member of that family. We have recently isolated a number of related phages and five showed high similarity to Φ12 in the amino acid sequences of several proteins. Bacteriophage Φ2954 is a member of this group.  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