全文获取类型
收费全文 | 60406篇 |
免费 | 4625篇 |
国内免费 | 2096篇 |
专业分类
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 |
出版年
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.
F. D. Knollmann J. C. Bck S. Teltenktter W. Wlodarczyk A. Mühler Th. J. Vogl R. Felix 《Journal of magnetic resonance imaging : JMRI》1997,7(1):191-196
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.
环孢霉素A和地塞米松局部应用对角膜移植免疫排斥的疗效观察 总被引:2,自引:1,他引:1
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.
L.A. BROWN M. WISELKA A. CAMPBELL J.H. PRINGLE K. NICHOLSON I. LAUDER 《Histopathology》1991,19(3):225-230
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