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   29548篇
  免费   2788篇
  国内免费   2162篇
耳鼻咽喉   216篇
儿科学   405篇
妇产科学   344篇
基础医学   3395篇
口腔科学   572篇
临床医学   3945篇
内科学   4501篇
皮肤病学   267篇
神经病学   1431篇
特种医学   1271篇
外国民族医学   12篇
外科学   3357篇
综合类   4810篇
现状与发展   7篇
一般理论   3篇
预防医学   1911篇
眼科学   681篇
药学   3144篇
  28篇
中国医学   1588篇
肿瘤学   2610篇
  2024年   93篇
  2023年   441篇
  2022年   1102篇
  2021年   1378篇
  2020年   1031篇
  2019年   936篇
  2018年   961篇
  2017年   915篇
  2016年   935篇
  2015年   1316篇
  2014年   1603篇
  2013年   1462篇
  2012年   1945篇
  2011年   2334篇
  2010年   1492篇
  2009年   1160篇
  2008年   1500篇
  2007年   1575篇
  2006年   1521篇
  2005年   1482篇
  2004年   1132篇
  2003年   1144篇
  2002年   1026篇
  2001年   868篇
  2000年   799篇
  1999年   750篇
  1998年   440篇
  1997年   505篇
  1996年   334篇
  1995年   299篇
  1994年   233篇
  1993年   193篇
  1992年   229篇
  1991年   213篇
  1990年   182篇
  1989年   164篇
  1988年   133篇
  1987年   136篇
  1986年   119篇
  1985年   76篇
  1984年   50篇
  1983年   28篇
  1982年   16篇
  1981年   17篇
  1980年   25篇
  1979年   45篇
  1978年   22篇
  1976年   12篇
  1975年   18篇
  1974年   20篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
通过兔后肢缺血模型,观察了甘露醇和低温对骨骼肌缺血再灌流损伤的保护作用。结果:甘露醇和低温可以不同程度地降低再灌流后患肢静脉回流血中细胞内酶(CPK、LDH、AST)的活性和脂质过氧化反应终末代谢产物丙二醛(MDA)的含量,减轻骨骼肌细胞超微结构的破坏。两者单独应用效果不明显(P>0.05),联合应用效果非常明显(P<0.01)。提示自由基介导的脂质过氧化反应参与骨骼肌缺血再灌流损伤,甘露醇和低温对其具有协同保护作用。  相似文献   
92.
为探讨药效法估测的效应消除半衰期和效量法估测的表观半衰期对合理制订给药方案的意义和作用,以桂枝汤解热和抗炎的药物动力学实验中所得的相应参数值设计了给药方案,观察了它们在提高药效上的作用。结果表明在给药总剂量相等、首次给药同时开始的情况下,以半衰期设计的给药方案组的药效均明显高于习惯的一次给药组;而以效应消除半衰期设计给药方案组药效增强率又高于以表观半衰期设计的方案组。提示效应消除半衰期比表观半衰期似更有实践意义。  相似文献   
93.
In an experimental study on a piggery it was found that haemolytic Escherichia coli of O-serotypes 138 or 139 proliferated in the intestinal tracts of pigs following weaning, with E. coli of the O-138 type also being occasionally recovered from unweaned pigs, and once from a sow. Organisms of the O-138 type produced heat labile enterotoxin and their presence in weaned pigs was associated with the development of severe post-weaning diarrhoea. E. coli of O-139 type produced a vero cell cytotoxin and were associated with a milder diarrhoea in weaned pigs. Under various managemental circumstances the O-138 type E. coli almost invariably proliferated after weaning. The O-139 strain of E. coli did however proliferate rather than the O-138 strain following the movement of weaned pigs to new accommodation, after weaned pigs were returned to their sow and then weaning again 5 days later, and very occasionally in pigs weaned at 5 weeks of age. In all these cases earlier proliferation of the O-138 E. coli had been detected, suggesting that this may be a prerequisite for proliferation of the O-139 strain.  相似文献   
94.
Polyclonal antibodies directed against human recombinant basic fibroblast growth factor were used in immunohistochemical studies to localize this growth factor in normal and wounded rat skeletal muscles. According to the intensity of the stain, three main classes of fibers could be identified: the strongly, moderately, and weakly stained fibers. Basic fibroblast growth factor immunoreactivity was found mainly in the extracellular matrix, primarily in the endomysium, which includes the heparin-containing basal lamina, and also in the capillary basal membrane of both normal and wounded muscles; however, the signal intensity was much stronger in normal muscles. The distribution of basic fibroblast growth factor in wounded muscles became markedly heterogeneous and sparse. After 4 hours of ischemia, about 40% of skeletal muscle fibers lost their basic fibroblast growth factor immuno-reactivity. Muscles which underwent 4 hours of ischemia and 24 hours of reperfusion had only a diminished basic fibroblast growth factor immunoreactivity. The pathologic results supported the concept of destroyed cell connection and fiber necrosis in ischemic and reperfused muscles. Potential mechanisms involved in this reduced concentration of basic fibroblast growth factor in wounded muscles may include oxygen free radical activation, a generalized effect of the inflammatory response, and reduced secretion of endogenous basic fibroblast growth factor. These results are only partially compatible with the established mitogenic role of this growth factor and suggest that a reduction of endogenous fibroblast growth factor may partly contribute to a delay in wound healing.  相似文献   
95.
Soluble lens crystallins from 6-10-week-old, galactose-fed, male Sprague-Dawley rats were analyzed by two-dimensional polyacrylamide gel electrophoresis at each of the five Sippel stages of cataractogenesis. Electrophoretograms were compared with similarly analyzed crystallins from comparably aged, chow-fed controls. Polypeptides were assigned to crystallin families and subfamilies on the basis of chromatographic fractionations with Sephadex G-200, superfine. Staining intensities of polypeptides from control lenses remained essentially unchanged throughout the experimental period, while those of the polypeptides from cataractous lenses showed non-uniform changes. Staining of the genomic gamma-crystallins increases up to at least stage 3; by stage 4, staining of gamma-chains, with perhaps those of gamma 5 and gamma 6 excepted, diminishes and in the total cataract, staining of all chains is further reduced. With possibly the addition of one chain, the total number of postsynthetically modified gamma-crystallins in cataractous lenses does not exceed that in the comparably aged normal lens. The genomic alpha- and beta-crystallin polypeptides are sustained close to normal levels up to stages 3 or 2, respectively, after which their gradually falling levels are accompanied by the generation of new species or elevated levels of existing post-translational species. An exception to this behavior is the rapid and total loss of beta B1a, a genomic subunit implicated in the aggregation of beta H-crystallins. Charge heterogeneity and variable pI displayed by beta B1a and other highly cationic beta- and gamma-crystallin polypeptides can be induced during isoelectric focusing and may be due to thiol group oxidation.  相似文献   
96.
汽车后送伤员附加装置隔振设计   总被引:2,自引:2,他引:0  
采用钢丝绳隔振器设计了运输车后送伤员附加装置的隔振结构,并进行了隔振性能试验。5名受试者的试验结果表明,隔振装置的隔振性能良好,可衰减40%—70%的振动能量。本文为运输车后送伤员附加装置的隔振设计提供了一种新方法。  相似文献   
97.
Six cases of Dp+/Gp+, 10 cases of D/G translocation, 1 case of supernumerary marker chromosome, and 1 case of Yqs were studied using molecular and cytogenetic techniques. The Ag-NOR frequencies of the Dp+ and Gp+ groups were found to be higher than those of normal controls, while their satellite association frequencies were lower. Autoradiographic silver grains were not significantly distributed along the p+ part of the marker chromosome as revealed by chromosomal in situ hybridization using an rRNA probe. This result differs from our previous report. It is suggested that there might be different mechanisms for the formation of p+ on acrocentric chromosomes. D/G translocation cases were found to have lost their NOR. A study of supernumerary marker chromosomes and Yqs cases suggested that the marker chromosome and Yqs exerted no phenotypic effect. The mechanism of their formation is discussed.  相似文献   
98.
本文采用中和试验、沉降反应和解离试验对135例已知血型人精液中ABH血型物质的分泌强度进行了检验,并将其分为强、中、弱三型。这对区别个人血型物质含量及性犯罪的法医学鉴定均有重要意义。并证明了AB型人精液中A、B血型物质含量不均等现象,并且绝大多数人B型物质高于A型物质。  相似文献   
99.
氟罗沙星的体内外试验相关性研究   总被引:4,自引:1,他引:3  
本文研究了新型喹诺酮类药物氟罗沙星体外溶出与体内吸收之间的相关性。实验表明,本品口服吸收在血清中达峰时间较快,作用持久,消除半衰期为9.60hr。在人工胃液中溶出速率较快,在血清达峰之前,体内吸收与体外溶出量之间呈现良好的相关性。  相似文献   
100.
分析了1984~1993年期间47例经治的急性视神经炎患者。治疗应用地塞米松10mg、青霉素480万u静脉点滴7天,随后减量。结果治愈35例(74.47%),好转6例(12.76%),无效2例(4.26%),转院及自动出院各2例。47例中11例治疗效果不好者行筛窦开放术后,视力逐渐恢复正常,显示筛窦开放术有其临床实用价值。  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