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   34589篇
  免费   3475篇
  国内免费   2539篇
耳鼻咽喉   212篇
儿科学   485篇
妇产科学   392篇
基础医学   4218篇
口腔科学   621篇
临床医学   4465篇
内科学   5371篇
皮肤病学   314篇
神经病学   1553篇
特种医学   1146篇
外国民族医学   29篇
外科学   3737篇
综合类   5994篇
现状与发展   9篇
一般理论   3篇
预防医学   2390篇
眼科学   933篇
药学   3789篇
  32篇
中国医学   2010篇
肿瘤学   2900篇
  2024年   166篇
  2023年   696篇
  2022年   1661篇
  2021年   2099篇
  2020年   1452篇
  2019年   1251篇
  2018年   1219篇
  2017年   1137篇
  2016年   1045篇
  2015年   1554篇
  2014年   1945篇
  2013年   1747篇
  2012年   2494篇
  2011年   2797篇
  2010年   1718篇
  2009年   1361篇
  2008年   1718篇
  2007年   1821篇
  2006年   1685篇
  2005年   1612篇
  2004年   1146篇
  2003年   1103篇
  2002年   962篇
  2001年   784篇
  2000年   763篇
  1999年   762篇
  1998年   452篇
  1997年   477篇
  1996年   367篇
  1995年   346篇
  1994年   337篇
  1993年   185篇
  1992年   227篇
  1991年   241篇
  1990年   239篇
  1989年   185篇
  1988年   154篇
  1987年   120篇
  1986年   124篇
  1985年   93篇
  1984年   70篇
  1983年   41篇
  1982年   27篇
  1981年   22篇
  1980年   17篇
  1979年   20篇
  1977年   16篇
  1975年   14篇
  1974年   19篇
  1969年   13篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Linkage studies in multiple sclerosis (MS) identified several susceptibility loci. One of these regions includes chromosome 17q11 where a meta-analysis of data from three genome scans suggested linkage. This region encodes a cluster of genes for beta-chemokines or CC chemokine ligands (CCLs), which may be involved in the development of MS lesions. Here we aimed to test if CCL alleles and haplotypes are associated with MS. Using methods of linkage and association, we observed deviations from the expected 50% transmission of haplotypes from unaffected parents to their affected children at CCL2, CCL11-CCL8-CCL13 and CCL3 within the investigated 1.85 MB chromosomal segment. Analyses of the linkage disequilibrium map support that variants with possible relevance to MS can be located within these subregions. Identification of MS associated CCL variants may have direct clinical significance, as it can lead to the design of small competitive antagonists of these molecules with beneficial effects in the treatment of patients with early and active disease.  相似文献   
42.
Summary Purified hepatitis B virus particles were obtained from HBeAg positive serum by sucrose gradient ultracentrifugation and sephadex G-200 gel filtration. These virions formed a precipitation line in counterimmune electrophoresis with anti-albumin antibody, but the reaction could be inhibited by anti-HBs. After two months at 4°C, another precipitating line was formed under the same condition which could not be inhibited by anti-HBs and was, thus, due to free albumin. When that sample was incubated at 37°C overnight, the line of free albumine disappeared. The virion bound albumin was monomeric in non-denaturing gel electrophoresis. These results suggest that a reversible binding between virion and albumin may occur in vivo and does not require chemical modification or cross-linking.  相似文献   
43.
Abstract: Low and high resolution sequence specific oligonucleotide probe hybridization patterns were used to design an approach to direct sequencing of allele specific amplified cDNA. Several PCR amplifications were used to derive overlapping sequence fragments to define complete first domain sequences for a single allele. This method has been used to characterize three new DRB1 alleles in the DR52 family, DRB1*1115, DRB1* 1117, and DRB1*1319. All three alleles carry polymorphisms previously observed in other DRB alleles and underscore the importance of utilizing a directed sequencing approach for obtaining unambiguous typing results in matching for bone marrow transplantation between unrelated donor and recipient.  相似文献   
44.
Yuan X  Yao Z  Shan Y  Chen B  Yang Z  Wu J  Zhao Z  Chen J  Cong Y 《Virus research》2005,114(1-2):70-79
The open reading frame 3 (ORF3) of the severe acute respiratory syndrome coronavirus (SARS-CoV) genome encodes a predicted 154-amino acid protein, which lacks similarities to any known protein, and is named 3b. In this study, it was shown that 3b protein was predominately localized to nucleus with EGFP tag at its N- or C-terminus. The localization patterns were similar in different transfected cells. Immuno-fluorescence assay revealed that 3b protein was co-localized well with C23 in nucleolus. C23, B23 and fibrillarin all are important nucleolar proteins, which localize in the region of the nucleolus. Co-transfection of p3b-EGFP with pC23-DsRed, pB23-DsRed and pfibrillarin-DsRed further confirmed 3b's nucleolus localization. With construction of serial truncated mutants of 3b, a region (residues 134-154 aa) responsible for nucleolar localization was determinated in 3b protein. These results provide a new insight for further functional studies of SARS-CoV 3b protein.  相似文献   
45.
Gene therapy is defined as the introduction of a therapeutic gene into a cell, whose expression can lead to a cure of a disease or offer a transient advantage for tissue growth and regeneration. The delivery of genes can be undertaken for a number of purposes, usually it is attempted to enhance or add a function to a cell or a tissue or to delete or reduce another function. In this brief overview we describe various vehicles and techniques that have been developed to deliver therapeutic genes into cells, such as viral vectors and physical/chemical gene delivery methods including naked DNA and particle-mediated gene transfer, the microseeding technique and the application of lipids. Furthermore we review the potential utility of gene therapy from the perspective of a reconstructive surgeon. Several tissues will be discussed, particularly muscle, tendon, nerve, bone, skin and wounds.  相似文献   
46.
Citrin is a mitochondrial aspartate glutamate carrier primarily expressed in the liver, heart, and kidney. We found that adult-onset type II citrullinemia is caused by mutations in the SLC25A13 gene that encodes for citrin. In this report, we describe the frequency of SLC25A13 mutations, the roles of citrin as a member of the urea cycle and as a member of the malate-aspartate shuttle, the relationship between its functions and symptoms of citrin deficiency, and therapeutic issues.  相似文献   
47.

Background  

In multiple sclerosis, inflammatory cells are found in both active and chronic lesions, and it is increasingly clear that cytokines are involved directly and indirectly in both formation and inhibition of lesions. We propose that cytokine mixtures typical of Th1 or Th2 lymphocytes, or monocyte/macrophages each induce unique molecular changes in glial cells.  相似文献   
48.
Objective: The effect of rosiglitazone, a potent peroxisome proliferator-activated receptor γ (PPAR-γ) agonist, on pulmonary inflammation in endotoxemia was investigated. Materials and methods: Male Wistar rats were given either lipopolysaccharide (LPS, 6 mg/kg i.v.) or saline, pretreated with rosiglitazone (0.3 mg/kg i.v.) or its vehicle (dimethyl sulphoxide) 30 min before LPS. The selective PPAR-γ antagonist GW9662 (0.3 mg/kg i.v.) was given 20 min before rosiglitazone. Wet/dry weight (W/D) ratio, myeloperoxidase (MPO) activity, malondialdehyde (MDA) as well as TNF-α and CINC-1 concentrations were measured in lung tissues 4 h after LPS injection. Expression of ICAM-1, NF-κB p65 and PPAR-γ were also determined by immunohistochemistry or Western blot analysis. Results: Rosiglitazone pretreatment significantly attenuated the increases in W/D ratio, MPO activity and MDA levels, and reduced pulmonary overproduction of TNF-α and CINC-1 as well as expression of ICAM-1 following endotoxemia. Rosiglitazone also inhibited the nuclear localization of NF-κB and up-regulated the expression of PPAR-γ protein. The specific PPAR-γ antagonist GW9662 abolished the effect of rosiglitazone. Conclusion: These findings suggest that PPAR-γ agonists might be used as therapeutic agents in the therapy of inflammatory lung injury related to endotoxemia. Received 8 January 2005; returned for revision 6 July 2005; returned for final revision 20 July 2005; accepted by M. Katori 31 July 2005  相似文献   
49.
神经导航中脑组织变形补偿的点云处理   总被引:1,自引:0,他引:1  
有限元方法是解决神经导航中脑组织变形的重要方法,需要手术过程中的脑皮层信息作为其边界条件.本文通过非结构点云进行了脑皮层信息的表示,并通过对其进行处理来获取有限元方法的边界条件.点云处理包括纹理映射、分割、简化和去噪,其中非结构点云的简化与去噪采用了改进的基于表面特性k邻域的聚类方法.实验结果证明所采用的点云处理方法是可靠的.  相似文献   
50.
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