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   133213篇
  免费   9112篇
  国内免费   456篇
耳鼻咽喉   1698篇
儿科学   3464篇
妇产科学   2356篇
基础医学   17249篇
口腔科学   2597篇
临床医学   13337篇
内科学   27768篇
皮肤病学   2103篇
神经病学   12586篇
特种医学   4789篇
外国民族医学   4篇
外科学   19458篇
综合类   2115篇
现状与发展   1篇
一般理论   174篇
预防医学   12038篇
眼科学   3117篇
药学   9225篇
  2篇
中国医学   174篇
肿瘤学   8526篇
  2023年   541篇
  2022年   879篇
  2021年   2187篇
  2020年   1297篇
  2019年   2159篇
  2018年   2464篇
  2017年   1899篇
  2016年   2072篇
  2015年   2542篇
  2014年   3609篇
  2013年   5588篇
  2012年   8111篇
  2011年   8660篇
  2010年   4905篇
  2009年   4755篇
  2008年   8363篇
  2007年   8887篇
  2006年   8754篇
  2005年   9013篇
  2004年   8502篇
  2003年   8311篇
  2002年   7876篇
  2001年   1470篇
  2000年   1219篇
  1999年   1474篇
  1998年   1814篇
  1997年   1532篇
  1996年   1276篇
  1995年   1270篇
  1994年   1040篇
  1993年   1051篇
  1992年   975篇
  1991年   901篇
  1990年   853篇
  1989年   831篇
  1988年   722篇
  1987年   727篇
  1986年   708篇
  1985年   838篇
  1984年   970篇
  1983年   945篇
  1982年   1256篇
  1981年   1109篇
  1980年   1014篇
  1979年   578篇
  1978年   643篇
  1977年   617篇
  1976年   509篇
  1975年   462篇
  1974年   437篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
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   
32.
33.
背景:Parkin基因(PRKN)突变可导致常染色体隐性遗传性早发帕金森病(EOPD)。目的:探讨EOPD白人家族PRKN突变的表现和基因型-表型关系。设计:对EOPD家族的3代20例成员进行基因分析,该家族有4例患者。应用直接基因组DNA测序、半定量聚合酶链反应、实时定量聚合酶链反应以及逆转录酶聚合酶链反应分析以确定PRKN突变。结果:4例早发患者(年龄30—38岁)被确定有PRKN复合杂合突变(T240M和EX5_6缺失),虽然PRKN的杂合T240M和纯合EX5_6缺失突变已有描述,但是据悉,本文为上述复合杂合突变的首次报道。患者的表型为典型常染色体隐性遗传性EOPD的表现,其特征是对左旋多巴治疗有效、相对缓慢的进展和运动障碍。所有杂合突变的基因携带者(T240M或EX5_6缺失)和1例56岁的复合杂合突变女性携带者(T240M和EX5_6缺失)无任何神经系统症状。结论:研究发现,PRKN基因复合杂合突变(T240M和EX5_6缺失)导致一个大的白人家族中4例成员发生常染色体隐性遗传性EOPD。另外1例成员具有相同的突变,比4例患者的平均发病年龄大10岁,并且无本病的临床表现。不完全的外显率对遗传咨询具有暗示作用,并且提示复杂的基因一环境交互作用在PRKN相关EOPD的发病机制中发挥作用。  相似文献   
34.
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   
35.
36.
37.
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   
38.
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   
39.
Patients with multiple system atrophy (MSA) present large changes in blood pressure (BP) due to autonomic disturbances. We analyzed how this change may influence dynamic cerebral autoregulation (DCA). Simultaneous recordings of arterial BP (Finapres) and middle cerebral artery (MCA) blood flow velocity (BFV) (transcranial Doppler) were performed in 10 patients with MSA (61 +/- 12 yr of age) and 12 healthy volunteers (61 +/- 11 yr of age): cerebral BFV response to oscillations in mean BP was studied in the supine position by cross-spectral analysis of mean BP and mean MCA BFV. The DCA was also studied during the decrease in BP the first seconds when standing up from a sitting position by the assessment of the cerebrovascular resistance index (CR; mean BP/mean MCA BFV ratio). The MCA BFV/BP cross-spectral analysis showed a phase for the mid-frequency band (0.07-0.2 Hz) significantly larger in MSA, suggesting more active autoregulation in response to larger changes in BP. Changes in CR reflecting the rate of autoregulation, when standing did not differ between the two groups. These data suggest that dynamic cerebral autoregulation is preserved in MSA.  相似文献   
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