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   185503篇
  免费   34126篇
  国内免费   2568篇
耳鼻咽喉   5637篇
儿科学   6210篇
妇产科学   3105篇
基础医学   7824篇
口腔科学   3674篇
临床医学   29079篇
内科学   56470篇
皮肤病学   8257篇
神经病学   17625篇
特种医学   7153篇
外科学   46137篇
综合类   477篇
现状与发展   72篇
一般理论   13篇
预防医学   9738篇
眼科学   4004篇
药学   2985篇
中国医学   150篇
肿瘤学   13587篇
  2024年   705篇
  2023年   4998篇
  2022年   1771篇
  2021年   4389篇
  2020年   6683篇
  2019年   3191篇
  2018年   8547篇
  2017年   8058篇
  2016年   9212篇
  2015年   9354篇
  2014年   16865篇
  2013年   17344篇
  2012年   8425篇
  2011年   8556篇
  2010年   12066篇
  2009年   15625篇
  2008年   8260篇
  2007年   6539篇
  2006年   8892篇
  2005年   6130篇
  2004年   5028篇
  2003年   3810篇
  2002年   3689篇
  2001年   3956篇
  2000年   3118篇
  1999年   3395篇
  1998年   3924篇
  1997年   3672篇
  1996年   3550篇
  1995年   3390篇
  1994年   2086篇
  1993年   1678篇
  1992年   1476篇
  1991年   1495篇
  1990年   1106篇
  1989年   1221篇
  1988年   1070篇
  1987年   895篇
  1986年   933篇
  1985年   769篇
  1984年   601篇
  1983年   585篇
  1982年   558篇
  1981年   451篇
  1980年   428篇
  1979年   348篇
  1978年   372篇
  1977年   444篇
  1975年   302篇
  1972年   320篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
The present study aimed at measuring seropositivities for infection by Ascaris suum and Toxocara canis using the excretory/secretory (E/S) antigens from Ascaris suum (AES) and Toxocara canis (TES) within an indigenous population. In addition, quantification of cytokine expressions in peripheral blood cells was determined. A total of 50 Warao indigenous were included; of which 43 were adults and seven children. In adults, 44.1% were seropositive for both parasites; whereas children had only seropositivity to one or the other helminth. For ascariosis, the percentage of AES seropositivity in adults and children was high; 23.3% and 57.1%, respectively. While that for toxocariosis, the percentage of TES seropositivity in adults and children was low; 9.3% and 14.3%, respectively. The percentage of seronegativity was comparable for AES and TES antigens in adults (27.9%) and children (28.6%). When positive sera were analyzed by Western blotting technique using AES antigens; three bands of 97.2, 193.6 and 200.2 kDas were mostly recognized. When the TES antigens were used, nine major bands were mostly identified; 47.4, 52.2, 84.9, 98.2, 119.1, 131.3, 175.6, 184.4 and 193.6 kDas. Stool examinations showed that Blastocystis hominis, Hymenolepis nana and Entamoeba coli were the most commonly observed intestinal parasites. Quantification of cytokines IFN-γ, IL-2, IL-6, TGF-β, TNF-α, IL-10 and IL-4 expressions showed that there was only a significant increased expression of IL-4 in indigenous with TES seropositivity (p < 0.002). Ascaris and Toxocara seropositivity was prevalent among Warao indigenous.  相似文献   
33.
34.
35.
36.
Chlorpyrifos is the most used insecticide in Argentina. Cnesterodon decemmaculatus is a widely distributed, endemic fish from Neotropical America. It attains high densities in the shallow water assemblages of Argentina and Brazil. The aim of this study was to assess the acute toxicity of chlorpyrifos to C. decemmaculatus. The mean 96-h LC50 of three independent determinations was 105.3 (±?3.1) μg/L. Sublethal effects were observed. Swimming behavioral changes at each chlorpyrifos exposure concentration were reported. C. decemmaculatus represents a good model for ecotoxicological risk assessment.  相似文献   
37.
Bowel diseases of prematurity, including necrotizing enterocolitis, are dreaded ailments of neonates. Early diagnosis is difficult, with clinical and radiographic findings often inconclusive. We present a novel use of contrast-enhanced ultrasound in detection of pediatric bowel disease. Early identification of compromised blood flow or an at-risk bowel can be quantitatively detected and monitored. This ability has implications for guidance of emerging therapies, allowing targeting of inflammation. These findings represent an advancement in detection of bowel disease in neonates.  相似文献   
38.
The association between asbestos exposure, mainly in occupational settings, and malignant mesothelioma has been well established; this has prompted several countries to establish mesothelioma epidemiologic surveillance programs often at the request of national agencies. This review compares currently existing mesothelioma registries worldwide to develop a concept model for a US real-time case capture mesothelioma registry. Five countries were identified with a mesothelioma specific registry, including Italy, France, UK, Australia, and South Korea. All, except the UK, used interviews to collect exposure data. Linkage with the national death index was available or was in future plans for all registries. The registries have limited information on treatment, quality of life, and other patient-centered outcomes such as symptoms and pain management. To thoroughly collect exposure data, “real-time” enrollment is preferable; to maximize the capture of mesothelioma cases, optimal coverage, and a simplified consent process are needed.  相似文献   
39.
40.
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