全文获取类型
收费全文 | 29375篇 |
免费 | 2548篇 |
国内免费 | 1054篇 |
专业分类
耳鼻咽喉 | 338篇 |
儿科学 | 439篇 |
妇产科学 | 588篇 |
基础医学 | 5700篇 |
口腔科学 | 403篇 |
临床医学 | 2507篇 |
内科学 | 3867篇 |
皮肤病学 | 384篇 |
神经病学 | 926篇 |
特种医学 | 1100篇 |
外国民族医学 | 1篇 |
外科学 | 2772篇 |
综合类 | 4459篇 |
现状与发展 | 2篇 |
预防医学 | 1252篇 |
眼科学 | 143篇 |
药学 | 2269篇 |
6篇 | |
中国医学 | 821篇 |
肿瘤学 | 5000篇 |
出版年
2024年 | 343篇 |
2023年 | 399篇 |
2022年 | 815篇 |
2021年 | 947篇 |
2020年 | 900篇 |
2019年 | 627篇 |
2018年 | 653篇 |
2017年 | 764篇 |
2016年 | 843篇 |
2015年 | 853篇 |
2014年 | 1670篇 |
2013年 | 1774篇 |
2012年 | 1680篇 |
2011年 | 1806篇 |
2010年 | 1531篇 |
2009年 | 1457篇 |
2008年 | 1530篇 |
2007年 | 1557篇 |
2006年 | 1404篇 |
2005年 | 1275篇 |
2004年 | 1176篇 |
2003年 | 1027篇 |
2002年 | 851篇 |
2001年 | 844篇 |
2000年 | 678篇 |
1999年 | 666篇 |
1998年 | 530篇 |
1997年 | 518篇 |
1996年 | 455篇 |
1995年 | 440篇 |
1994年 | 418篇 |
1993年 | 282篇 |
1992年 | 245篇 |
1991年 | 183篇 |
1990年 | 223篇 |
1989年 | 176篇 |
1988年 | 139篇 |
1987年 | 125篇 |
1986年 | 101篇 |
1985年 | 167篇 |
1984年 | 188篇 |
1983年 | 96篇 |
1982年 | 133篇 |
1981年 | 105篇 |
1980年 | 94篇 |
1979年 | 89篇 |
1978年 | 46篇 |
1977年 | 43篇 |
1976年 | 50篇 |
1975年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
The purpose of this work was to evaluate the efficiency of free-flow electrophoresis as a method for separating mouse lymphocyte subsets. The surface phenotype of the cells contained in the various fractions collected after electrophoresis of CBA/J lymph node cells was investigated by means of single- and 2-color flow cytofluorometry (FCF) analysis. In agreement with previous works, B cells (sIg+, Thy-1-) were found to segregate in the low mobility (LM) fractions and T cells (sIg-, Thy-1+) in the high-mobility (HM) fractions. While the mean fluorescence intensity of sIg staining did not significantly vary as a function of electrophoretic mobility (EPM) that of Thy-1 staining tended to decrease with increasing EPM. The distribution of Lyt-1+ cells was roughly parallel to that of Thy-1+ cells. However, 2-color FCF analysis suggested the existence, in addition to a major Thy-1+ Lyt-1+ subpopulation, of a minor subset of Thy-1- Lyt-1+ cells. Lyt-2+ cells made up a peak in the cathodic HM region where they were enriched by up to 3-fold, and a trail in the more anodic HM fractions. Two-color FCF analysis showed that all Lyt-2+ cells recovered in these various electrophoretic fractions expressed the Lyt-1 antigen. Taken together, these data demonstrate that free-flow electrophoresis provides a powerful tool for the delineation and substantial enrichment of phenotypically distinct mouse peripheral T cell subsets. 相似文献
42.
Lysenko ON Strizhova NV Kholodova ZhL 《Bulletin of experimental biology and medicine》2003,135(1):77-80
No appreciable disorders of cellular immunity were detected in patients with glandular cystic endometrial hyperplasia. Atypical endometrial hyperplasia was associated with quantitative changes in T lymphocytes and their subpopulations, decreased level of lymphocytes carrying activation antigens, and increased count of natural killers. These changes can be characterized as immunocompensation. 相似文献
43.
Zak-Prelich M McKenzie RC Sysa-Jedrzejowska A Norval M 《Clinical and experimental immunology》2003,131(2):318-323
Varicella zoster virus (VZV) causes varicella (chickenpox) as the primary infection and zoster (shingles) on reactivation from latency, often many years later. One of the most common and most severe sequela of zoster is postherpetic neuralgia (PHN). Apart from age, factors which predispose towards PHN are unknown. In the present study, the concentration of a variety of Th1 and Th2 cytokines in the serum of 30 zoster patients at the time of the acute disease were correlated with the subsequent development of PHN in nine of these patients, but no association was found. In addition, although some cytokines such as IFN-gamma, IL-6 and IL-8 were slightly raised in the zoster group compared with a group of normal healthy subjects of a similar age distribution, these differences only verged on significance. Antibody titres to VZV were raised in the zoster group compared with the controls but these did not differ between the patients who developed PHN and those who did not. Biopsies of zoster lesions were collected from nine patients. There were significantly fewer infiltrating lymphocytes in the lesions of the three patients who subsequently developed PHN compared with the six who did not, although the expression of the neuropeptide, substance P, did not differ between the two groups. It is possible that the poor inflammatory response at the time of the acute zoster may result in less effective containment of the VZV and more damage in the dermatome, thus contributing to the persistence of the neuralgia. 相似文献
44.
Mature T cells residing in peripheral lymphoid organs have frequent contact with antigen presenting cells (APC). Such contact may be required for T cell survival, but the degree to which signals in mature T cells are induced by TCR recognition of self peptide/MHC complexes is unclear. We have used induction of the early growth response gene 1 (Egr1) as an indicator of signal transduction in 3.L2 (I-Ek-restricted) T cells interacting with APC in the absence of exogenous antigen. The data show that Egr1 can be induced in 3.L2 T cells by TCR recognition of self peptides presented by I-Ek. However, a more transient induction of Egr1 can be induced in 3.L2 T cells interacting with dendritic cells derived from class II/beta2m double-deficient mice. Egr1 induction after T cell-APC contact was also observed in a freshly isolated polyclonal CD4 T cell population. The data suggest that self peptide/MHC recognition by the TCR induces a signal in T cells and that dendritic cells can also induce a more transient T cell signal by an MHC-independent mechanism. 相似文献
45.
Lack EE 《Virchows Archiv : an international journal of pathology》1999,435(2):87-91
The Association of Directors of Anatomic and Surgical Pathology has developed recommendations for the surgical pathology report
for common malignant tumors. The recommendations for tumors of the adrenal cortex and medulla are reported herein.
Received: 30 March 1999 / Accepted: 30 March 1999 相似文献
46.
Mayne M Moffatt T Kong H McLaren PJ Fowke KR Becker KG Namaka M Schenck A Bardoni B Bernstein CN Melanson M 《European journal of immunology》2004,34(4):1217-1227
DNA microarray profiling of CD4(+) and CD8(+) cells from non-treated relapsing and remitting multiple sclerosis (MS) patients determined that the cytoplasmic binding partner of fragile X protein (CYFIP2, also called PIR121) was increased significantly compared to healthy controls. Western analysis confirmed that CYFIP2 protein was increased approximately fourfold in CD4(+) cells from MS compared to inflammatory bowel disorder (IBD) patients or healthy controls. Because CYFIP2 acts as part of a tetrameric complex that regulates WAVE1 activation we hypothesized that high levels of CYFIP2 facilitate T cell adhesion, which is elevated in MS patients. Several findings indicated that increased levels of CYFIP2 facilitated adhesion. First, adenoviral-mediated overexpression of CYFIP2 in Jurkat cells increased fibronectin-mediated adhesion. Secondly, CYFIP2 knock-down experiments using antisense oligodeoxynucleotides reduced fibronectin-mediated binding in Jurkat and CD4(+) cells. Thirdly, inhibition of Rac-1, a physical partner with CYFIP2 and regulator of WAVE1 activity, reduced fibronectin-mediated adhesion in Jurkat and CD4(+) cells. Finally, inhibition of Rac-1 or reduction of CYFIP2 protein decreased fibronectin-mediated adhesion in CD4(+) cells from MS patients to levels similar to controls. These studies suggest that overabundance of CYFIP2 protein facilitates increased adhesion properties of T cells from MS patients. 相似文献
47.
Congenital insensitivity to pain with anhidrosis is a syndrome characterized by loss of pain and sensation. The condition frequently evolves into deep wounds and prolonged healing times. Anhidrosis is another prominent component of the disorder. Often associated with recurrent episodes of unexplained fever, it can result in patient mortality. Recent investigations point to Trk A, the high affinity receptor for nerve growth factor (NGF), as a candidate for the site of the mutation that causes the disorder. Functional NGF receptors, such as Trk A and the Trk family of tyrosine kinases, are essential for NGF signaling of human lymphocytes. In this study, we demonstrated that the presence of a trk A mutation in patient B cells results in a novel lymphocyte signaling defect. In these B cells, NGF failed to induce Trk A phosphorylation, cytoskeleton assembly, or MAP kinase activation. These abnormalities may explain some of the clinical features of the disease. 相似文献
48.
K. N. Fedorova 《Bulletin of experimental biology and medicine》1976,82(1):1093-1095
A luminescence-microscopic investigation of short-term human cell cultures stained with Acridine Orange showed that the melting curve of the cell chromatin DNA in the region from 78 to 85°C depends on changing external environmental conditions, i.e., on the composition of the blood serum.Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Yudaev.Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 7, pp. 878–879, July, 1976. 相似文献
49.
目的 研究人外周血CD4^ /CD8^ T细胞4种神经营养素受体基因的转录。方法 应用尼龙手法分离出T细胞,磁式细胞分离法(MACS)分离CD4^ /CD8^ T细胞亚群,再以RT-PCR法研究4种神经营养素受体在两种T细胞亚群上的表达。结果 未经刺激的CD4^ /CD8^ T细胞亚群不表达任何神经营养素受体。经PHA或PPD刺激后,CD4^ /CD8^ T细胞亚群表达trkA,CD8^ T细胞亚群表达trkC;而在各种状态下的T细胞上均未见表达trkB及p75^NGFR。结论神经营养素受体在两种T细胞亚群中有不同的表达格局,提示不同T细胞亚群受神经营养素调节的模式可能各不相同。 相似文献
50.
We have used a set of single-chain variable fragment antibodies (sc) genetically fused with an influenza hemagglutinin-derived peptide as a means to investigate the role of CR1 and CR2 in antigen presentation by B cells. When incubated with the B cell lymphoma 2PK3, peptide-containing sc specific for either CR1 or CR1/2 mediated activation of the hemagglutinin peptide-specific T cell line IP-12-7, as assessed by IL-2 production. Efficient presentation was dependent on the binding of the constructs to CR1/2, implying that receptor-mediated endocytosis is responsible for the effect. Cross-linkage of CR1/2 or CD19 by mAb did not increase the extent of T cell activation. However, when CR1/2 was co-ligated with the BCR--using either polyclonal goat anti-mouse IgG or recombinant protein LA--the antigen concentration required to activate T cells decreased by two orders of magnitude. Moreover, this enhancement was selective for the antigen included in these complexes and did not affect the presentation of a free peptide or of antigen bound to CR1/2 excluded from the complexes. These results suggest that B cells may bind various C3d-coated antigens at a time, but only the one which reacts with the BCR will be processed with high efficiency. This mechanism may ensure the specificity of cognate T cell help. 相似文献