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   127944篇
  免费   8784篇
  国内免费   461篇
耳鼻咽喉   1705篇
儿科学   3388篇
妇产科学   2217篇
基础医学   16539篇
口腔科学   2424篇
临床医学   12876篇
内科学   27226篇
皮肤病学   1954篇
神经病学   12384篇
特种医学   4350篇
外国民族医学   4篇
外科学   18484篇
综合类   1917篇
现状与发展   1篇
一般理论   169篇
预防医学   11319篇
眼科学   3027篇
药学   8918篇
  2篇
中国医学   174篇
肿瘤学   8111篇
  2023年   479篇
  2022年   708篇
  2021年   2094篇
  2020年   1248篇
  2019年   2062篇
  2018年   2363篇
  2017年   1824篇
  2016年   2001篇
  2015年   2467篇
  2014年   3495篇
  2013年   5445篇
  2012年   7888篇
  2011年   8403篇
  2010年   4760篇
  2009年   4583篇
  2008年   8071篇
  2007年   8666篇
  2006年   8485篇
  2005年   8777篇
  2004年   8319篇
  2003年   8121篇
  2002年   7697篇
  2001年   1318篇
  2000年   1062篇
  1999年   1349篇
  1998年   1752篇
  1997年   1465篇
  1996年   1194篇
  1995年   1182篇
  1994年   975篇
  1993年   984篇
  1992年   864篇
  1991年   817篇
  1990年   781篇
  1989年   723篇
  1988年   667篇
  1987年   622篇
  1986年   641篇
  1985年   761篇
  1984年   914篇
  1983年   906篇
  1982年   1210篇
  1981年   1100篇
  1980年   995篇
  1979年   553篇
  1978年   640篇
  1977年   599篇
  1976年   499篇
  1975年   445篇
  1974年   427篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
41.
42.
A high resolution depth attenuation product (Kdhires) was developed using MODIS 500 m and 250 m spectral bands. The Kdhires was compared with Wang’s operational Kd for the Chesapeake Bay. Minimal differences were observed between the two methods, with greatest deviation occurring in areas of high turbidity in the tributaries. After tuning the new Kdhires, the mean absolute error and bias between the two algorithms was 0.22 m?1 and 0.026 m?1, indicating good agreement. Higher spatial resolution provides for improved retrievals along the coast and into the narrow sections of the tributaries, coinciding with areas of concern to estuarine health and coastal management applications.  相似文献   
43.
Lasers in Medical Science - Using light sources in phototherapy has presented promising results regarding several types of facial and body skin affections for centuries. The neodymium-doped yttrium...  相似文献   
44.
45.
Epistaxis is a common ear, nose and throat emergency. A variety of nasal packs are available to control the bleeding by tamponade. Training of junior doctors to insert nasal packs is difficult when dealing with a bleeding patient. We discovered a readily available and simple model to enable trainees to learn the method of nasal packing.  相似文献   
46.
47.
48.
49.
Richard Ila  Michele Solem 《Alcohol》2006,39(3):169-178
Previously, we have demonstrated that chronic-alcohol exposure alters insulin-like growth factor 1 (IGF1) signaling in adult rat heart cells. This report examines the effects of alcohol in vitro on the expression of protein kinase C (PKC) alpha, delta, and epsilon using the embryonic heart cell line, H9c2, and how this may be linked to changes in IGF1 signal transduction. Western blot analyses of H9c2 protein preparations demonstrate that there are significant increases in the total protein levels of PKC delta and epsilon after 4 days exposure to alcohol, and similar increases were found after 2 and 6 days exposure. In addition, there was a significant increase in PKC delta and epsilon in the membranal fractions and a decrease in the cytosolic fractions. No change was found in the expression or activity levels for PKC alpha. Chronic-alcohol exposure (100 mM, 4 days) increased the basal tyrosine kinase activity of the IGF1 receptor (IGF1R), and altered its rate of activation. Chronic-alcohol exposure also reduced the rate of Erk1/Erk2 activation by IGF1. Chronic alcohol blocked the proliferative effects of IGF1 on cell growth and reduced cell viability both in the presence and absence of IGF1, and this alcohol-induced reduction in cell viability was blocked using siRNA to inhibit PKC delta. In addition, a reduction in the amount of myosin light chain 2 was found in the alcohol-exposed cells. In conclusion, chronic alcohol alters PKC delta and epsilon expression and activity, and suppresses the IGF1 signaling pathway in embryonic heart cell culture. Blockage of PKC delta expression using siRNA inhibits the suppressive effects of alcohol on cell viability.  相似文献   
50.
Severe persistent asthma can have a substantial impact on a patient's health-related quality of life (HRQL), both as a result of symptoms and from side effects of treatment. The HRQL impact of two doses (400 and 800 microg twice daily) of mometasone furoate dry powder inhaler (MF DPI) was compared with placebo in patients with severe persistent asthma previously maintained on oral steroids as a component of a previously published randomized, 12-week, double-blind, placebo-controlled, multicenter trial. A 9-month open-label extension (OLE), with all patients treated with MF DPI, followed. Patients 12 years of age or older completed a generic HRQL measure, the Medical Outcomes Trust Short Form-36 (SF-36), and an asthma-specific measure, the Marks Asthma Quality of Life Questionnaire (AQLQ-M), at baseline, at endpoint (last evaluable visit) of the double-blind phase (EODBP), and after the first 3 months of the OLE. Of 132 patients enrolled in the study, 128 provided HRQL data at baseline and at EODBP. Mean SF-36 scores at baseline showed significant HRQL impairment compared with U.S. general population norms. With treatment, the reduction in oral corticosteroid (OCS) requirements of the MF-DPI-treated groups was accompanied by significant (p < 0.05) improvement over placebo in the physical domain of HRQL (SF-36 physical component summary score and the physical function subscale) at EODBP. MF-DPI-treated patients also showed significant improvements at EODBP in each of the four subscales of the AQLQ-M (p<0.05). From EODBP to the OLE 3-month endpoint, patients treated with MF DPI twice daily maintained, or improved, SF-36 scores in most domains. Symptomatic improvement and reduction in OCS use with MF DPI were accompanied by significant improvement in HRQL in patients with severe persistent asthma. These improvements were maintained during the 3-month period of the OLE in which HRQL was evaluated.  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