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   1443篇
  免费   120篇
  国内免费   60篇
耳鼻咽喉   12篇
儿科学   51篇
妇产科学   21篇
基础医学   139篇
口腔科学   31篇
临床医学   197篇
内科学   341篇
皮肤病学   23篇
神经病学   38篇
特种医学   306篇
外科学   158篇
综合类   37篇
预防医学   77篇
眼科学   11篇
药学   54篇
中国医学   28篇
肿瘤学   99篇
  2021年   11篇
  2019年   16篇
  2018年   27篇
  2017年   14篇
  2015年   28篇
  2014年   30篇
  2013年   62篇
  2012年   42篇
  2011年   32篇
  2010年   34篇
  2009年   32篇
  2008年   35篇
  2007年   78篇
  2006年   33篇
  2005年   36篇
  2004年   38篇
  2003年   38篇
  2002年   21篇
  2001年   25篇
  2000年   25篇
  1999年   30篇
  1998年   58篇
  1997年   43篇
  1996年   71篇
  1995年   62篇
  1994年   46篇
  1993年   51篇
  1992年   20篇
  1991年   21篇
  1990年   29篇
  1989年   44篇
  1988年   46篇
  1987年   56篇
  1986年   45篇
  1985年   43篇
  1984年   35篇
  1983年   20篇
  1982年   17篇
  1981年   27篇
  1980年   25篇
  1979年   12篇
  1978年   20篇
  1977年   19篇
  1976年   14篇
  1975年   15篇
  1974年   8篇
  1973年   11篇
  1972年   11篇
  1970年   7篇
  1968年   7篇
排序方式: 共有1623条查询结果,搜索用时 0 毫秒
1.
2.
We describe a novel human zinc finger cNDA, C2H2-171. This cDNA represents an mRNA which encodes a protein of 484 amino acids and a calculated molecular weight of 54 kD. Four zinc finger-like domains are found in the C-terminal end of the protein. At the N-terminus, C2H2-171 contains a POZ/tramtrack-like domain similar to that found in the tumor associated zinc finger proteins LAZ-3/BCL-6 and PLZ-F, as well as in non-zinc finger proteins. C2H2-171 RNA is preferentially expressed in the brain, and increases during the course of murine development, with maximal expression in the adult. C2H2-171 RNA is differentially expressed in brain regions, with the highest level of expression in the cerebellum. C2H2-171 RNA was expressed at high levels in primary cerebellar granule cell neurons compared to astrocytes. The gene encoding C2H2-171 is highly conserved in vertebrates, and maps to the terminus of human chromosome 1 (1q44-ter). This chromosomal location is associated with a number of cytogenetic aberrations including those involving brain developmental anomalies and tumorigenesis. These data suggest that C2H2-171 may play an important role in vertebrate brain development and function.  相似文献   
3.
4.
C2H2-type zinc finger genes comprise one of the largest genefamilies in the human genome. These proteins are involved ingenetic regulation and development and are quite conserved throughoutevolution. The finger domains commonly contain the small linkerpeptide TGEKP between some finger units. Here, we report theisolation of 133 human zinc finger cDNAs, of which 118 are novel.These clones were isolated from human brain cDNA libraries usingoligonucleotide hybridization followed by expressed sequencetag (EST) analysis, sequencing from the conserved linker regionusing degenerate oligonucleotide primers. This directed partialsequencing approach to cDNA isolation and characterization,signature sequencing, combines the speed of EST automatic sequencingwith the focus of specific cDNA family analysis. Signature sequencingminimizes the generation of less informative random EST sequencesand provides a unique relative position for sequence comparison.We also show that there is an even distribution of these RNA5from this brain cDNA library, and that these cDNAs contain N-terminaldomains found in other zinc finger genes. This rapid focusedsequencing approach should be applicable to any family of cDNAscontaining short conserved signature peptide sequences.  相似文献   
5.
6.
The purpose of this investigation was to determine if there was any relationship between dietary carnitine intake and the concentrations of carnitine in skeletal muscle and blood plasma in healthy adult men and women. Subjects (14 men, 14 women, fasted 8 h) reported to the Biodynamics Laboratory where they completed a 24-h diet recall questionnaire. Resting muscle biopsy (vastus lateralis) and blood plasma samples were taken and assayed for free, short-chain, and long-chain acyl carnitine concentrations. Dietary carnitine intake was estimated from data on concentrations in food. There was no significant relationship between either protein or carnitine intake with skeletal muscle carnitine concentrations. There was a significant relationship between both dietary carnitine (r = 0.50) and protein (r = 0.48) intake with blood plasma total acid soluble carnitine concentrations (p less than 0.01) in all subjects.  相似文献   
7.
Spirometry can be used as an objective tool for measuring nasal patency. it is sensitive, easy to perform, comfortable to patient The only limitation being that it only can be done in institution.  相似文献   
8.
The structural gene for diphtheria toxin, tox, has been modified at its Sph I site by the introduction of an oligonucleotide linker encoding a unique Pst I restriction endonuclease site and a synthetic oligonucleotide encoding alpha-melanocyte-stimulating hormone (alpha-MSH). The resulting fusion gene directs the expression of a diphtheria toxin-related alpha-MSH hybrid protein in which the diphtheria toxin receptor-binding domain has been replaced with alpha-MSH sequences. The chimeric toxin has been partially purified from periplasmic extracts of recombinant Escherichia coli K-12 and has been found to be selectively toxic for alpha-MSH receptor-positive human malignant melanoma NEL-M1 cells in vitro.  相似文献   
9.
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