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   60406篇
  免费   4625篇
  国内免费   2096篇
耳鼻咽喉   382篇
儿科学   1408篇
妇产科学   741篇
基础医学   9053篇
口腔科学   800篇
临床医学   4593篇
内科学   9400篇
皮肤病学   1169篇
神经病学   4904篇
特种医学   861篇
外国民族医学   11篇
外科学   4449篇
综合类   6410篇
现状与发展   10篇
预防医学   4811篇
眼科学   995篇
药学   10406篇
  8篇
中国医学   3062篇
肿瘤学   3654篇
  2023年   837篇
  2022年   1345篇
  2021年   1927篇
  2020年   1807篇
  2019年   2404篇
  2018年   2341篇
  2017年   2014篇
  2016年   1920篇
  2015年   2118篇
  2014年   3320篇
  2013年   4066篇
  2012年   3439篇
  2011年   4099篇
  2010年   3408篇
  2009年   2819篇
  2008年   2657篇
  2007年   2499篇
  2006年   2114篇
  2005年   1842篇
  2004年   1638篇
  2003年   1515篇
  2002年   1239篇
  2001年   1088篇
  2000年   831篇
  1999年   849篇
  1998年   697篇
  1997年   646篇
  1996年   556篇
  1995年   487篇
  1994年   437篇
  1993年   409篇
  1992年   371篇
  1991年   348篇
  1990年   306篇
  1989年   247篇
  1988年   243篇
  1986年   183篇
  1985年   806篇
  1984年   1036篇
  1983年   821篇
  1982年   941篇
  1981年   888篇
  1980年   662篇
  1979年   619篇
  1978年   444篇
  1977年   356篇
  1976年   408篇
  1975年   311篇
  1974年   193篇
  1973年   196篇
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
131.
Alcohol and Platelet Function   总被引:3,自引:0,他引:3  
Epidemiological studies have shown that moderate consumption of alcoholic beverages is inversely related to the incidence of the complications of coronary artery disease. The protective effect of ethanol may be partially attributable to an inhibitory effect of ethanol on platelets. This article summarizes the experimental observations that ethanol inhibits platelet responses to specific physiological agonists. In alcoholics, various platelet defects have been observed, but these may be influenced by metabolic factors rather than the presence of ethanol alone. The acute effects of ethanol on platelet functions both in vivo and ex vivo will be reviewed. Evidence will be presented demonstrating that ethanol added acutely in vitro inhibits phospholipase A2 in stimulated platelets. The interaction of ethanol with other signal transduction pathways will also be discussed.  相似文献   
132.
本文采用俯卧拍背法缓解胆绞痛41例,其中23例经此法治疗后疼痛立即消失(56.1%);15例明显缓解(36.6%);3例缓解不明显(7.3%)。具有操作简便、安全,易被患者接受,值得推广。  相似文献   
133.
Prevention of nutritional deficiencies should be attained by the consumption of a good diet. Unfortunately, in the case of iron, this is not always possible, and it is advantageous to fortify food with iron. Milk-based formulas and cereals are the most commonly used iron-fortified products in infancy and early childhood. Bioavailability of iron from cereals is low and more clinical studies on the field are necessary to demonstrate the effectiveness of iron-fortified cereals in infants and children of developing countries. Infections and excessive blood loss in infancy related to the use of fresh, pasteurized or powdered cow milk result in much of the anemia we currently see in industrialized countries. Vitamin A deficiency interacts with iron metabolism and recent intervention studies have shown that anemia in Vitamin A deficient children can be successfully treated with oral supplements.  相似文献   
134.
The purpose of our research was to determine the effects of superparamagnetic iron oxide on MR imaging of the portal venous system. Eight piglets were examined in deep anaesthesia and respiratory arrest using a time-of-flight magnetic resonance fast low angle shot, two-dimensional angiography sequence at 1.5T. MR angiograms were acquired precontrast and after intravenous administration of a cumulative dose of 10, 20 and 40 μmol/kg SHU 555A, a superparamagnetic iron oxide contrast agent for MR imaging with a particle size of 60 nm. For each dose, two subsequent sets of scans were obtained and reconstructed by a maximum-intensity-projection algorithm. Hepatic parenchymal and portal venous signal intensities were measured, and portal vein contrast calculated for each set of scans. All examinations were visually rated as to portal vein contrast and homogeneity by two blinded observers. Receiver operating characteristics of both observers were analyzed. The contrast agent reduced hepatic parenchymal signal in a dose-dependent way. After a cumulative dose of 10 μmol iron oxide, hepatic parenchymal signal intensity decreased to 63 ± 6% (average of measurements at 4 and 14 minutes, mean ± standard error of the mean), after 20 μmol to 24 ± 3%, and after 40 μmol to 12 ± 1% of control. Intra-vascular signal in the left main portal vein branch increased to 117 ± 6%, 127 ± 10%, and 133 ± 9% of control, respectively. The contrast-to-noise ratio of the portal vein improved (521 ± 90%, 891 ± 178%, and 995 ± 201% of control in the left portal vein main branch). Intravascular signal intensities increased slightly. The combined effect improved contrast of the portal vein stem and its branches. Receiver operating characteristics analysis documented dose-dependency of contrast medium effects on portal venous contrast and intravascular homogeneity. Visual rating also indicated a positive effect on portal venous contrast. The superparamagnetic iron oxide agent improved portal venous contrast with surrounding hepatic parenchyma in this normal animal model, and could potentially result in more accurate diagnosis of portal venous pathology.  相似文献   
135.
谢立信  曹景 《眼科研究》1995,13(1):24-26
报告1%环孢霉素A(CyclosporinA,CsA)和地塞米松局部联合用药,治疗31只眼穿透性角膜移植术后的免疫排斥反应,随访6~18个月植片透明治愈为93.5%,平均治愈时间7天,观察表明局部用药既能收到良好的疗效,又避免了全身用药的毒副作用,并对CsA和地塞米松联合用药的机理及注意事项进行了讨论。  相似文献   
136.
A 47-year-old man with persistent severe oropharyngeal ulceration developed a high-grade T-cell lymphoma soon after commencing treatment with cyclosporin A. Using Southern blotting to identify T-cell beta-chain gene rearrangements, evidence of clonal restriction was found both in blood and lymph node DNA samples. Two BamH1 rearranged bands were demonstrated in both samples. In the blood a 16 Kb band predominated, with a weaker 28 kb band. In the lymph node sample this pattern was reversed. The findings suggest that a bi-clonal population of T-lymphocytes or clonal evolution of an existing T-cell monoclone had developed, and that cyclosporin contributed to the emergence of a high-grade T-cell lymphoma.  相似文献   
137.
Adultacuteleukemia (AL)isoneofthemostcommonmalignanttumorsofhematology .Withtherecentprogressinchemotherapyandsupportivether apy ,theremissionandsurvivalrateinALhavebeenmarkedlyimproved .However ,drugresistanceandrelapsearestillimportantfactorsaffectinglongsur vivalofthese patients .Theabnormalregulationofcellcycleisanotherfactorthatcannotbeignoredex ceptformultipledrugresistance (MDR) .WedetectcyclinA ,multidrugresistantgene (mdrl) ,topoiso meraseⅡα(TopⅡα)andbcl 2inadultpatientswithA…  相似文献   
138.
高浓度吗啡对体外培养的小鼠淋巴细胞增殖的抑制效应北京医科大学药理学教研室陆正武,林志彬利用不同刺激原诱导的淋巴细胞增殖反应,研究吗啡的体外作用机制。结果表明:(1)高浓度吗啡(≥0.1mmol·L-1)以剂量依赖方式,抑制ConA/LPS所致淋巴细胞...  相似文献   
139.
140.
利用气相色谱—质谱—计算机联用仪分析了云南省腾冲县产珠子参挥发油的成份,从中鉴定了27种化合物,测定了它们的相对含量,其中有10种倍半萜烯和一种倍半萜醇。  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