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   18199篇
  免费   1853篇
  国内免费   1275篇
耳鼻咽喉   119篇
儿科学   221篇
妇产科学   219篇
基础医学   2130篇
口腔科学   307篇
临床医学   2530篇
内科学   2744篇
皮肤病学   191篇
神经病学   967篇
特种医学   706篇
外国民族医学   16篇
外科学   1588篇
综合类   3162篇
现状与发展   9篇
一般理论   3篇
预防医学   1128篇
眼科学   435篇
药学   1998篇
  30篇
中国医学   1205篇
肿瘤学   1619篇
  2024年   89篇
  2023年   369篇
  2022年   908篇
  2021年   1094篇
  2020年   830篇
  2019年   691篇
  2018年   735篇
  2017年   670篇
  2016年   586篇
  2015年   846篇
  2014年   1122篇
  2013年   928篇
  2012年   1297篇
  2011年   1393篇
  2010年   907篇
  2009年   734篇
  2008年   952篇
  2007年   876篇
  2006年   858篇
  2005年   844篇
  2004年   604篇
  2003年   561篇
  2002年   481篇
  2001年   399篇
  2000年   423篇
  1999年   393篇
  1998年   237篇
  1997年   217篇
  1996年   205篇
  1995年   173篇
  1994年   156篇
  1993年   105篇
  1992年   110篇
  1991年   76篇
  1990年   92篇
  1989年   62篇
  1988年   46篇
  1987年   56篇
  1986年   38篇
  1985年   35篇
  1984年   30篇
  1983年   25篇
  1982年   9篇
  1981年   5篇
  1978年   4篇
  1976年   5篇
  1975年   7篇
  1973年   8篇
  1972年   4篇
  1968年   6篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
作者在18只尸体手标本上,对拇指背动脉进行了显微解剖研究,发现该动脉出现率较恒定,起始部血管外径平均为0.63mm,动脉可解剖长度为7.2cm,血管分布范围包括第一掌骨背侧、部份鱼际区及拇指近节背桡侧5×10cm 的皮肤。以拇指背动脉及与其相连的桡动脉远段为蒂,可以游离成一个理想的岛状皮瓣,适用于拇指再造及邻近的组织缺损修复。  相似文献   
73.
MALDI-TOF MS has potential as a valuable technique in DNA mapping studies and may well be complementary to other approaches to DNA analysis such as gel electrophoresis and sequencing. This study used 2,6-dihydroxyacetophenone (DHAP) mixed with diammonium hydrogen citrate (DAHC) as the matrix. In addition, recent technical advances such as time lag focussing (TLF) and better selection of matrices (such as 3-hydroxypicolinic acid (3 HPA) and picolinic acid (PA)) extended the range of DNA fragments that can be studied by this approach. The following samples were investigated: Poly-T mixture (dT 15, 19, 20, 25, 74 and 75), plasmid pBR322 derived oligonucleotides (10, 11, 12, 13, 14, 15, 19, 20 and 50 nucleotides long) and DNA fragments of 25, 36 and 37 base pairs corresponding to a fragment in the restriction map for the gene corresponding to the hexon protein of Adenovirus 2 and 5. The results were contrasted with similar analyses performed by ion-paired reversed-phase HPLC coupled to on-line electrospray mass spectrometry.  相似文献   
74.
白云  朱锡华 《免疫学杂志》1994,10(4):214-217
用抗CD59单抗2A7与CNBr-Sepharose4B偶联制备亲和层析柱,从正常人红细胞膜蛋白抽提物中分离纯化出CD59分子。本法纯化的CD59分子量为18-20KDa对还原剂敏感,与McAbssMEM43和1F5有高亲和性,再掺入豚鼠红细胞后,能够抑制人体补体的反应性溶血,本文还对三株抗CD59单抗2A7,MEM43及1F5的抗原特异性进行了初步分析。  相似文献   
75.
Prominent in T cells and natural killer cells, CD2 binding protein 1 (CD2BP1) plays an important role in CD2-mediated adhesion and signal transduction. In the current study, we investigated CD2 and PSTPIP (proline, serine, threonine phosphatase interacting protein, murine homologue of CD2BP1) interactions in purified mouse splenic T cells. PSTPIP associated with CD2 in both resting and activated T cells. Following various stimuli, such as concanavalin A, anti-TCRbeta, anti-CD3epsilon, anti-CD3epsilon/phorbol myristate acetate (PMA), IL-2, or PMA/ionomycin, PSTPIP and CD2 expression, as well as their association, increased in a time-dependent fashion. While PSTPIP expression and CD2 expression were comparable across most groups, the PSTPIP-CD2 association stimulated by anti-CD3epsilon alone was significantly greater than with other stimuli. Stimulation by anti-CD3epsilon plus anti-CD28 induced even greater PSTPIP-CD2 association than anti-CD3epsilon treatment alone, indicating that CD28 initiated signals are involved in regulating this interaction. There was no direct association between CD3epsilon or CD28 and PSTPIP. Tyrosine phosphorylated PSTPIP bound poorly to CD2 compared to dephosphorylated PSTPIP, and protein tyrosine phosphatase was shown to affect both phosphorylation of PSTPIP and the CD2-PSTPIP association. In addition to CD2, PSTPIP associated with CD4, CD8, CD54, and CD62L. CD2 and CD4 ligation reciprocally regulated their association with PSTPIP. These findings indicate that T cell activation, particularly through the CD3 and CD28 signal transduction pathways, regulates PSTPIP-CD2 interactions. PSTPIP likely has additional broader effects through interactions with CD4, CD8, CD54, and CD62L, and this may influence T cell responses to antigen.  相似文献   
76.
Based on our finding that a common epitope exists between HIV-1 gp41 and human type I interferons (IFN-alpha and IFN-beta), and increased levels of antibodies against human IFN-alpha and IFN-beta were observed in HIV-1-infected individuals, we tried to explain the mechanism of increased levels of antibodies. Mouse antisera recognizing HIV-1 recombinant soluble (rs) gp41 (aa 539-684) interacted with two synthetic peptides sequence-corresponding to the IFN-alpha/beta receptor binding site on human IFN-alpha and IFN-beta, while normal mouse serum (pooled normal sera) did not. The anti-rspg41 antisera after adsorption by IFN-beta sepharose column lost the activity of interaction with both synthetic peptides. In another experiment, rsgp41 could bind to sepharose column conjugated with anti-IFN-beta polyclonal antibodies (IgG). These results indicate that the common epitope on gp41 and type I interferons could induce antibodies recognizing the receptor binding site on IFN-alpha and IFN-beta, suggesting that increased levels of antibodies against IFN-alpha and IFN-beta in HIV-1-infected individuals could be induced by gp41.  相似文献   
77.
78.
皮质—网状—脊髓通路——HRP法结合溃变电镜法研究   总被引:2,自引:1,他引:2  
白德成 《解剖学杂志》1998,21(3):219-223
用HRP逆行标记法结合溃变电镜技术,观察了12只大鼠的蓝斑,外侧网状核,中缝大核,巨细胞网状核在旁正中网状核中皮质纤维终末的超微结构及其与网状脊髓神经元的突触联系。损伤皮质感觉运动区的各例动物,均出现两种溃变型,电子致密型和微丝增生型。前者为皮质的主要溃变型,分布于各核;后者出现很少,只见于外侧网状核。电子致密型终扣有大小两种,大终扣少,有含圆形清亮型小泡,多形清亮型小泡,清亮型和颗粒型小泡并存的  相似文献   
79.
肾移植取肾方法的改进   总被引:1,自引:0,他引:1  
报道了自1985年2月至今共摘取供肾132例,取得尸肾263只(1例独立肾),其中251只供肾用于临床。分侧切取肾38例,整块切肾41例,改进后整块切肾53例。文中着重介绍改进后的整块切取尸肾的手术方法,讨论了术式的优缺点。  相似文献   
80.
1. Baclofen increases transient light responses of amacrine and ganglion cells despite acting as a classical inhibitory transmitter to both hyperpolarize and shunt these cells. 2. This effect seems to occur at the level of the inner retina and appears not to be due to an additional input from bipolar cells. 3. In some transient cells baclofen increases the total amplitude of the light response but does not change the peak potential of the light evoked EPSP. In these cells, the baclofen-induced enhancement can be accounted for by an increase in driving force of the excitatory postsynaptic potential (EPSP) resulting from the hyperpolarization. 4. However, in other cells the peak of the light response after baclofen application is greater, which cannot be accounted for by a change in driving force. This effect of baclofen can be mimicked by a blockers of gamma-aminobutyric acid (GABA) and glycine, suggesting that in these cells baclofen's enhancement is due in part to network effects resulting in a removal of sustained inhibition. 5. Therefore, the paradoxical effect of an inhibitory transmitter producing an enhancement of synaptic responses seems due to at least two mechanisms. 6. The results indicate that some transient cells receive significant tonic inhibition which limits their response amplitude in a push-pull type mechanism, but other cells are not under this inhibitory control process.  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