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   25537篇
  免费   2883篇
  国内免费   683篇
耳鼻咽喉   123篇
儿科学   428篇
妇产科学   279篇
基础医学   6895篇
口腔科学   630篇
临床医学   1694篇
内科学   3047篇
皮肤病学   559篇
神经病学   1342篇
特种医学   279篇
外国民族医学   7篇
外科学   2204篇
综合类   4145篇
预防医学   1179篇
眼科学   306篇
药学   2604篇
  6篇
中国医学   1466篇
肿瘤学   1910篇
  2024年   88篇
  2023年   377篇
  2022年   475篇
  2021年   758篇
  2020年   821篇
  2019年   1062篇
  2018年   1463篇
  2017年   725篇
  2016年   744篇
  2015年   748篇
  2014年   1467篇
  2013年   1758篇
  2012年   1375篇
  2011年   1724篇
  2010年   1393篇
  2009年   1473篇
  2008年   1302篇
  2007年   1189篇
  2006年   1147篇
  2005年   1086篇
  2004年   926篇
  2003年   765篇
  2002年   650篇
  2001年   452篇
  2000年   652篇
  1999年   589篇
  1998年   609篇
  1997年   376篇
  1996年   386篇
  1995年   325篇
  1994年   376篇
  1993年   331篇
  1992年   371篇
  1991年   155篇
  1990年   207篇
  1989年   76篇
  1988年   136篇
  1987年   85篇
  1986年   66篇
  1985年   95篇
  1984年   94篇
  1983年   34篇
  1982年   59篇
  1981年   15篇
  1980年   18篇
  1979年   14篇
  1978年   7篇
  1977年   11篇
  1976年   16篇
  1974年   14篇
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
101.
The chemoattractant cytokine IL-16 has been reported to suppress lymphocyte activation and to inhibit HIV-1 replication in acutely infected T cells. We have cloned and expressed human IL-16 in Escherichia coli and investigated whether the recombinant protein could regulate the level of lymphocyte apoptosis from HIV-1-infected subjects. After purification and refolding, only 2–10% of the recombinant cytokine was present in a biologically active homotetrameric form. This could explain the need for high concentrations of the bacterially derived IL-16 to induce significant inhibition of HIV-1 replication. Addition of IL-16 to unstimulated peripheral blood mononuclear cell (PBMC) cultures from HIV-1-infected subjects did not modify the observed level of spontaneous lymphocyte apoptosis. In contrast, IL-16 added to PBMC cultures stimulated with anti-CD3, anti-CD95 or dexamethasone reduced significantly the percentage of lymphocytes undergoing AICD. This effect was found to correlate with the ability of the cytokine to decrease CD95 expression on activated CD4+ T cells. Comparative studies on PBMC from healthy individuals indicated that the regulation of apoptosis levels by IL-16 is a complex phenomenon and could depend on the nature of the activator used and/or the immune status of lymphocytes tested. The outcome of CD4 cross-linking on T cells by various ligands is discussed in the context of the observed beneficial activities of IL-16 and its potential role in the treatment of HIV disease.  相似文献   
102.
观察三七多糖对创伤大鼠免疫功能的影响.方法:40只SD大鼠,随机分为正常对照组(A)、创伤对照组(B)、创伤后三七多糖28.5 mg·kg-1.  相似文献   
103.
Summary Effects of Chinese Medicinal Preparation “Re Du Qing” (RDQ) on the activation, proliferation and membrane fluidity of T lymphocytes from human peripheral blood Were studied by means of3H-TdR incorporation and DPH fluorescence polarization. The results showed that “RDQ” can:1) significantly inhibit the activation of T lymphocytes; 2) restrain the proliferation of activated T lymphoblasts in the presence of exogenous interleukin-2 (IL-2); and 3) increase the membrane fluidity of T lymphocytes and antagonize the decreased fluidity of lymphocyte membrane mediated by Con A or PHA. The functional abnormalities of T lymphocytes in some autoimmune diseases such as arthritis and the usefulness of RDQ in the treatment of these diseases were also discussed.  相似文献   
104.
As a part of any curriculum reorganization, new instructional methods are also tested. When the University of Turku sociology of medicine course was found to need renovation, its goals and objectives, content and instructional methods were closely examined and modified, in order to strengthen institutional and multiprofessional relations and reinforce sociocultural issues in doctors' competence with the patient. This paper discusses this change, emphasizing teaching and learning methodology.  相似文献   
105.
The modifying potential of two nephrotoxic agents, harman and norharman, on N-ethyl-N-hydroxyethylnitrosamine (EHEN)-induced renal and hepatic carcinogenesis was investigated in male F344/DuCrj rats. Animals were given 0.1% EHEN in their drinking water for the first 2 weeks as an initiator. Subsequently, starting 3 weeks from the commencement, they were fed diet containing these compounds at concentrations of 1000, S00 or 0 ppm until week 26, and then killed for light microscopic examination. The mean numbers of renal tubular cell hyperplasias/cm2 and those of tumors/cm2 in rats given harman and norharman at 1000 ppm after initiation, but not at 500 ppm, were significantly increased as compared to the control values. However, neither compound modified liver carcinogenesis. It is concluded that harman and norharman show enhancing effects on rat kidney carcinogenesis, when ingested at dose levels which cause renal tubular damage.  相似文献   
106.
We reviewed ninety-three patients who had one hundred and seven complete fractures of the femur between them and were treated over a twenty-five year period in Western Australia and South Australia. Operative surgical management of complete fractures in the middle and distal thirds was usually successful. In contrast, fractures proximal to the middle third were regularly associated with non-union, implant failure and requirement for revision surgery. In view of this significant difference in outcome after fracture of the pagetic femur in different sites, a comprehensive surgical management strategy is recommended in order to avoid complications.  相似文献   
107.
An impermeable thiol blocker has been used to investigate the role of sulphydryl (SH) groups in the production of and responsiveness to IL-2 by normal human T lymphocytes. Surface SH blockade of mononuclear cells prior to incubation with mitogen (phytohaemagglutinin, concanavalin A, CD3 MoAb) had no effect on production of IL-2 but markedly impaired cellular responsiveness to exogenous IL-2. Studies using MoAbs indicated that this effect was accompanied by decreased expression of both the CD25 and p75 subunits of the IL-2 receptor. Blocking surface SH groups did not affect binding of IL-2 to p75 on unstimulated mononuclear cells, but inhibited binding to high-affinity receptors on a T lymphoma cell line. The data are consistent with the hypothesis that sulphydryl groups on the IL-2 receptor are required for its function and may be involved in the interaction of the CD25 and p75 subunits leading to generation of the high-affinity binding site. The surface thiol identified on the IL-2 receptor may be a candidate for oxidation on cells from patients with chronic inflammatory diseases such as rheumatoid arthritis and thus contribute to the aberrant function of T cells in these patients.  相似文献   
108.
目的:探讨白细胞介素6(IL-6)、白细胞介素8(IL-8)与子宫内膜异位症(endomotriosisEMs)卵巢癌的发生发展关系。方法:采用双抗体夹心ABC-酶联免疫吸附实验(ELISA)对EMs患者30例、血清及腹腔液中IL-6、IL-8进行检测,并以卵巢癌患者10例、卵巢良性肿瘤患者30例、正常妇女血清30例做对照组。结果:EMs组与卵巢癌组患者血清及腹腔液中IL-6、IL-8水平明显高于对照组(P<0.01),EMs组与卵巢癌组对比无显著性差异(P>0.05)。结论:EMs患者腹腔液中IL-6、IL-8异常增高是腹腔免疫内环境失衡,与EMs的发生发展有关,在药物治疗中血清IL-6、IL-8可作为EMs疗效和预后的指标之一。  相似文献   
109.
P16MTS1、P27KIP1基因在胆管癌组织中的表达研究   总被引:2,自引:0,他引:2  
目的:探讨P16^MIS1,P27^KIP1基因与胆管癌临床病理的关系。方法:采用免疫组化方法,检测48例胆管癌和8例伴慢性炎症的胆管壁组织中P16^MIS1,P27^KIP1蛋白表达情况。结果:(1)胆管癌中P16^MIS1,P27^KIP1阳性表达率分别为47.9%和35.4%,而伴炎症的胆管组织阳性表达率为100%和87.5%;(2)P16^MIS1,P27KIP1蛋白表达与胆管癌的分化程度,有无淋巴结或远处转移以及临床分期呈显著相关性。结论:P16^MIS1,P27^KIP1多基因表达异常可能与胆管癌的发生发展有关,是衡量胆管癌预后的有用指标。  相似文献   
110.
流式细胞术检测98例献血者外周血HLA-B27的临床意义   总被引:5,自引:0,他引:5  
目的 通过对98例献血者外周血HLA—B27的检测,建立并优化测定HLA-B27的流式细胞术,并评价B7在早期辅助临床诊断以强直性脊柱炎为代表的脊柱关节病中的应用价值。方法 分别采用EDTA和肝素钠两种不同的抗凝剂,以及加单抗不同的量(7~30μl)检测2个B27阳性和9个B27阴性个体的全血,采用EDTA抗凝和15μl的单抗剂量检测献血者外周血,探寻流式细胞术检测HLA-B27的最佳实验条件;另以微量淋巴细胞毒实验分别对2例阳性标本和9例阴性标本进行验证。结果 通过微量淋巴细胞毒和流式细胞术两种方法检测98例献血者外周HLA-B27中2例为阳性,96例为阴性,且EDTA和肝素钠两种不同的抗凝剂,以及加单抗不同的量(7~30μl)对流式细胞术检测HLA-B7无任何影响。结论 优化并建立了一种简便省时、稳定性和重复性皆好的流式细胞仪用于检测HLA-B27的方法;HLA-B27与强直性脊柱炎高度相关,HLA-B27检测已成为临床支持以强直性脊柱炎为首的脊柱关节病的诊断与鉴别诊断的重要依据,具有重要的临床意义。  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