全文获取类型
收费全文 | 96632篇 |
免费 | 9390篇 |
国内免费 | 5689篇 |
专业分类
耳鼻咽喉 | 113篇 |
儿科学 | 4054篇 |
妇产科学 | 388篇 |
基础医学 | 7706篇 |
口腔科学 | 527篇 |
临床医学 | 8572篇 |
内科学 | 24624篇 |
皮肤病学 | 626篇 |
神经病学 | 1533篇 |
特种医学 | 3249篇 |
外国民族医学 | 20篇 |
外科学 | 24377篇 |
综合类 | 15086篇 |
现状与发展 | 31篇 |
一般理论 | 2篇 |
预防医学 | 2954篇 |
眼科学 | 1282篇 |
药学 | 6911篇 |
42篇 | |
中国医学 | 4596篇 |
肿瘤学 | 5018篇 |
出版年
2024年 | 207篇 |
2023年 | 1632篇 |
2022年 | 2625篇 |
2021年 | 3730篇 |
2020年 | 3813篇 |
2019年 | 3617篇 |
2018年 | 3605篇 |
2017年 | 3700篇 |
2016年 | 4065篇 |
2015年 | 3735篇 |
2014年 | 6121篇 |
2013年 | 6431篇 |
2012年 | 5169篇 |
2011年 | 6073篇 |
2010年 | 5024篇 |
2009年 | 4989篇 |
2008年 | 5104篇 |
2007年 | 5321篇 |
2006年 | 5238篇 |
2005年 | 4531篇 |
2004年 | 3663篇 |
2003年 | 3156篇 |
2002年 | 2663篇 |
2001年 | 2352篇 |
2000年 | 1982篇 |
1999年 | 1581篇 |
1998年 | 1466篇 |
1997年 | 1280篇 |
1996年 | 1176篇 |
1995年 | 979篇 |
1994年 | 1029篇 |
1993年 | 693篇 |
1992年 | 788篇 |
1991年 | 582篇 |
1990年 | 474篇 |
1989年 | 424篇 |
1988年 | 404篇 |
1987年 | 306篇 |
1986年 | 258篇 |
1985年 | 296篇 |
1984年 | 243篇 |
1983年 | 151篇 |
1982年 | 187篇 |
1981年 | 157篇 |
1980年 | 129篇 |
1979年 | 110篇 |
1978年 | 110篇 |
1977年 | 89篇 |
1976年 | 100篇 |
1975年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
放射损伤对于移植的骨髓间充质干细胞在受体大鼠不同器官中植入的影响 总被引:1,自引:0,他引:1
目的: 探讨放射损伤对于骨髓间充质干细胞(MSCs)移植后在受体大鼠不同器官中植入的影响以及可能的机制。方法:采用DNA缺口末端标记法(TUNEL)检测正常对照组和单纯放射组大鼠心脏、肾脏、肝脏、肺脏的细胞凋亡率。应用密度梯度离心法结合贴壁法提取雄性大鼠骨髓MSCs,培养后把MSCs移植到[60COγ]照射和未经照射的雌性大鼠体内,通过PCR和Y染色体荧光原位杂交(Y- FISH)示踪雄性大鼠MSCs在雌性大鼠体内的分布情况。结果:照射后大鼠心脏、肾脏、肝脏、肺脏细胞凋亡率显著高于对照组。PCR结果显示照射后移植MSCs的大鼠心脏、肾脏、肝脏、肺脏和外周血中可以扩增出Sry基因的DNA序列,而且Y- FISH显示照射后移植MSCs的大鼠在心脏、肾脏、肝脏、肺脏中可发现Y染色体阳性的细胞。但是未经照射行MSCs移植的大鼠在上述器官中未发现Y染色体阳性的细胞。结论:全身放射促进组织细胞的凋亡,并导致移植的MSCs在受体大鼠心脏、肾脏、肝脏和肺脏的植入。 相似文献
992.
血小板活化因子受体拮抗剂的抗内毒素肝损伤作用研究 总被引:2,自引:0,他引:2
本文研究了血小板活化因子受体拮抗剂BN52021及BN50739的抗大鼠内毒素肝损伤的作用。结果表明BN52021及BN50739能使内毒素所致的肝线粒体膜磷脂降解及溶血磷脂的聚集,脂质过氧化反应的增强以及机体抗氧化能力的降低得到明显改善,提示BN52021及BN50739是两种强有效的抗内毒素肝损伤的药物,用于内毒素肝损伤的治疗。 相似文献
993.
994.
PTEN基因对人肝癌细胞系HHCC作用的研究 总被引:4,自引:1,他引:4
目的:研究PTEN基因对人肝癌细胞系HHCC细胞恶性表型及凋亡的影响。方法:将PTEN真核表达载体pBabe-PuroPTEN及空质粒pBabe-Puro,通过脂质体介导的基因转染方法,转入该基因表达缺失的HHCC细胞系中,嘌呤霉素筛选获得稳定表达PTEN基因的转染细胞。通过平板克隆形成试验、DNA凝胶电泳、相差显微镜和电镜,观察PTEN基因对人肝癌细胞系HHCC恶性表型及凋亡的影响。结果:转染后的细胞,经原位杂交、免疫组织化学检测证实,有PTEN mRNA及其蛋白的表达;平板克隆形成试验证实,转染PTEN基因后,细胞形成克隆的能力降低;转染PTEN的细胞在相差显微镜和电镜下可出现典型的凋亡形态学改变;DNA琼脂糖凝胶电泳呈现出明显的梯状条带。结论:外源性PTEN基因导入HHCC细胞后,可降低HHCC的细胞的恶性表型,并促进凋亡发生。 相似文献
995.
Pernollet M Jouvin-Marche E Leroy V Vigan I Zarski JP Marche PN 《Clinical and experimental immunology》2002,130(3):518-525
Intrahepatic lymphocytes are believed to be involved in the immunopathogenesis of hepatitis C virus (HCV) infection and the evolution of HCV-induced hepatitis. In the present study, we examined the three main intrahepatic lymphocyte subsets, namely CD3+CD56- conventional T lymphocytes, CD3+CD56+ natural T (NT) lymphocytes and CD3-CD56+ natural killer (NK) lymphocytes in HCV-infected patients. The proportion of each lymphocyte subset was evaluated both in liver biopsies and in samples of peripheral blood lymphocytes (PBL) by flow cytometry in 21 patients with histologically proven chronic hepatitis C. Simultaneously, alanine aminotransferase (ALT) levels, viral load and histological lesions were assessed. Neither NT nor NK populations correlated with any biochemical, viral or histological parameters. Furthermore, Valpha24+ NT lymphocytes showed no preferential enrichment in the liver of HCV-infected patients. Regarding conventional T lymphocytes, a highly significant linear correlation was found between intrahepatic CD3+CD56- T lymphocytes and the Knodell score, a numerical score for assessing histological activity and fibrosis (r = 0.715, P < 0.0001) and more specifically with the periportal necrosis parameter, which is the main lesion of chronic hepatitis C. In addition, analysis of the peripheral compartment revealed a high correlation between values of CD3+CD56- lymphocytes and both Knodell score (r = 0.624, P = 0.003) and serum ALT levels and again with periportal necrosis. The strong correlation between the proportion of peripheral CD3+CD56- conventional T lymphocytes and the severity of hepatic lesions leads us to propose that evaluation of this accessible peripheral population could be used as an indicator test for the severity of histological lesions in chronic hepatitis C. Abbreviations: 相似文献
996.
Summary Techniques are described for the rapid isolation, monolayer culture, and phenotypical characterization of embryonic Day 12 (E12) rat liver epithelial cells. In vitro assays of the differentiation potential of these cells are currently being performed under conditions that make use of-modified Eagle's medium supplemented with fetal bovine serum, insulin, and dexamethasone with or without sodium butyrate. In the absence of sodium butyrate, the cells differentiate along the hepatocytic cell lineage, whereas in its presence they express the phenotype of the biliary ductal epithelial cell lineage. 相似文献
997.
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
998.
Intragastric infusion of amino acids causes the release from the liver of a factor with stimulatory effect on smooth muscle. The effect of liver vein plasma ultrafiltrate was tested on isolated preparations of rat fundus. The ultrafiltrates collected after amino acid infusion had a 3–5 times higher stimulatory effect on smooth muscle contraction than those collected from control plasma. The active principle was isolated, purified by different chromatographic procedures and identified as 5–hydroxytryptamine (serotonin). No other compound with contractile effect on smooth muscle was detected. 相似文献
999.
V. P. Komissarenko I. S. Chelnakova A. S. Mikosha 《Bulletin of experimental biology and medicine》1978,85(2):152-154
o,p-Dichlorodiphenyldichloroethane (o,p-DDD) and Perthane, when added in a concentration of 312 M to homogenate and cytoplasmic fraction of dog adrenals, activate glutathione reductase. In a concentration of 156 M, o,p-DDD and Perthane do not affect glutathione reductase activity of the dog adrenals. When given in vitro, o,p-DDD and Perthane activate glutathione reductase of the guinea pig adrenals. o,p-DDD has no effect on glutathione reductase activity of the cytoplasmic fraction of dog liver and kidney, thus confirming the high specificity of its effect on the adrenal cortex.Laboratory of Pathophysiology, Institute of Endocrinology and Metabolism, Kiev. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 2, pp. 159–161, February, 1978. 相似文献
1000.
Takatsugu Yamamoto Takashi Ikebe Shinichi Mikami Taichi Shuto Kazuhiro Hirohashi Hiroaki Kinoshita Masaml Sakurai 《Pathology international》1996,46(5):364-371
The sinusoidal structure and blood supply of 38 liver nodules less than 2 cm In diameter were Investigated. There were 18 cases of adenomatous hyperplasia (AH) and 20 cases of hepatocetlular carcinoma (HCC). Growth pattern, encapsulation and vascularity were examined, and Immunohistochemistry performed for factor VIII related antigen (factor VIII), type IV collagen (collagen IV), lamlnln and CD68. There were significant differences between AH and small HCC, except for the expression of CD68. There were differences In tumor size, vasculartty and the components of the basement membrane between AH and small, well differentiated HCC. The cases of AH were supplied by the portal system and maintained the sinusoidal structure, but small well-differentiated HCC were supplied by a mixture of portal and arterial vessels. In spite of their small size, moderately and poorly differentiated HCC had capillary and were supplied by branches of the hepatic artery. 相似文献