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   77768篇
  免费   8285篇
  国内免费   5055篇
耳鼻咽喉   619篇
儿科学   1306篇
妇产科学   689篇
基础医学   6912篇
口腔科学   1591篇
临床医学   9437篇
内科学   9687篇
皮肤病学   801篇
神经病学   3517篇
特种医学   3218篇
外国民族医学   27篇
外科学   7727篇
综合类   16702篇
现状与发展   14篇
一般理论   2篇
预防医学   6770篇
眼科学   2070篇
药学   8500篇
  58篇
中国医学   6227篇
肿瘤学   5234篇
  2024年   974篇
  2023年   1217篇
  2022年   2945篇
  2021年   3797篇
  2020年   3158篇
  2019年   2447篇
  2018年   2465篇
  2017年   2618篇
  2016年   2356篇
  2015年   3409篇
  2014年   4364篇
  2013年   4722篇
  2012年   6601篇
  2011年   6824篇
  2010年   5339篇
  2009年   4552篇
  2008年   4983篇
  2007年   4836篇
  2006年   4542篇
  2005年   3770篇
  2004年   3054篇
  2003年   2792篇
  2002年   2200篇
  2001年   1757篇
  2000年   1299篇
  1999年   952篇
  1998年   512篇
  1997年   568篇
  1996年   402篇
  1995年   335篇
  1994年   311篇
  1993年   193篇
  1992年   144篇
  1991年   137篇
  1990年   121篇
  1989年   90篇
  1988年   84篇
  1987年   69篇
  1986年   59篇
  1985年   29篇
  1984年   18篇
  1983年   21篇
  1982年   7篇
  1981年   5篇
  1980年   3篇
  1979年   4篇
  1970年   2篇
  1965年   3篇
  1963年   2篇
  1962年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Intravenous administration of human bone marrow stromal cells (hMSCs) after middle cerebral artery occlusion (MCAo) in rats provides functional benefit. We tested the hypothesis that these functional benefits are derived in part from hMSC production of growth and trophic factors. Quantitative sandwich enzyme‐linked immunosorbent assay (ELISA) of hMSCs cultured with normal and MCAo brain extracts were performed. hMSCs cultured in supernatant derived from ischemic brain extracts increased production of brain‐derived neurotrophic factor (BDNF), nerve growth factor (NGF), vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF). These neurotrophins and angiogenic growth factors increased in a post‐ischemia time‐dependent manner. The hMSC capacity to increase expression of growth and trophic factors may be the key to the benefit provided by transplanted hMSCs in the ischemic brain.  相似文献   
2.
吴仪 《中国骨伤》2007,20(9):585-586
2007年1月11日,中共中央政治局委员、国务院副总理吴仪在全国中医药工作会议上发表了重要讲话,该讲话从4个方面进行了论述,节选如下。  相似文献   
3.
Bone marrow stromal cells (MSCs) increase vascular endothelial growth factor (VEGF) expression and promote angiogenesis after stroke. Angiopoietin-1 (Ang1) and its receptor Tie2 mediate vascular integrity and angiogenesis as does VEGF and its receptors. In this study, we tested whether MSC treatment of stroke increases Ang1/Tie2 expression, and whether Ang1/Tie2 with VEGF/ vascular endothelial growth factor receptor 2 (VEGFR2) (Flk1), in combination, induced by MSCs enhances angiogenesis and vascular integrity. Male Wistar rats were subjected to middle cerebral artery occlusion (MCAo) and treated with or without MSCs. Marrow stromal cell treatment significantly decreased blood-brain barrier (BBB) leakage and increased Ang1, Tie2, and occludin (a tight junction protein) expression in the ischemic border compared with MCAo control. To further test the mechanisms of MSC-induced angiogenesis and vascular stabilization, cocultures of MSCs with mouse brain endothelial cells (MBECs) or astrocytes were performed. Supernatant derived from MSCs cocultured with MBECs significantly increased MBEC expression of Ang1/Tie2 and Flk1 compared with MBEC alone. Marrow stromal cells cocultured with astrocytes also significantly increased astrocyte VEGF and Ang1/Tie2 expression compared with astrocyte culture alone. Conditioned media from MSCs alone, and media from cocultures of MSCs with astrocytes or MBECs, all significantly increased capillary tube-like formation of MBEC compared with control Dulbecco's modified Eagle's medium media. Inhibition of Flk1 and/or Ang1 significantly decreased MSC-induced MBEC tube formation. Knockdown of Tie2 expression in MBECs significantly inhibited MSC-induced tube formation. Our data indicate MSC treatment of stroke promotes angiogenesis and vascular stabilization, which is at least partially mediated by VEGF/Flk1 and Ang1/Tie2.  相似文献   
4.
5.
Penetrating craniocerebral firearm injuries remain one of the most lethal causes of all trauma and are common both in war or peace time. Data were reviewed for 4140 severely head-injured patients (Glasgow Coma Scale (GCS) scores 3-8) treated at Xi-Jing Hospital between 1973 and 1993; 51 of these patients had acute penetrating craniocerebral injuries caused by firearm missiles. These patients consisted of 46 males (90.2%) and 5 females (9.8%) ranging in age from 3 months to 48 years (median 22.4 years). The lesion types included 2 tangential wounds, 37 tubular wounds and 12 through-and-through wounds. All cases were urgent with the patients in severe and unstable states. After emergency treatment and operation, 5 cases died (9.8%). Follow up studies at three months showed that 23 cases (45.1%) had made a good recovery. Moderate disability, severe disability and vegetative states in this series were 29.4%, 13.7% and 2.0% respectively. Long term follow up studies indicated that 32 were able to resume their occupation. The principles for managing penetrating craniocerebral firearm injuries and suggestions for operation are discussed.  相似文献   
6.
本文报告了1990年5月以来脑干区大型、复杂占位病变15例.其中,位于脑干内3例,脚间窝2例,岩尖部4例,全岩骨区1例,全斜坡区2例,第四脑室内3例.本组采用以扩大了的岩骨入路为主的联合入路,行肿瘤全切除8例,次全切除5例.2例仅作了活检加减压术.除1例死亡外,均恢复良好.本文结合文献,对脑干区手术入路进行了讨论.  相似文献   
7.
Abstract: Juvenile xanthogranuloma is a xanthomatous and granulomatous condition that frequently arises before 1 year of age and mainly occurs on the head and trunk. We report a rare solitary juvenile xanthogranuloma on the right palm of a 10-year-old girl, present for one year. This solitary involvement of the palm has been reported only twice before.  相似文献   
8.
Conventional computerized tomography (CT) technique is based on the absorption contrast. In recent years, X-ray phase-contrast CT (PCCT) has been developing rapidly. It uses the phase information to reconstruct the object and provide high contrast and spatial resolution. Diffraction enhanced imaging (DEI) method is one of the three phase-sensitive X-ray imaging techniques. DEI method employs an analyzer crystal to extract the object's refraction information which can be used for CT. However, when DEI refraction CT is combined with the conventional CT algorithm, it should be satisfied that the refraction information of an arbitrary point in the object is invariable at every projection view. In this paper, the invariance condition of refraction information is analyzed and two feasible methods are provided for reconstruction. Using these two methods, two samples of weak absorption are reconstructed with the experimental data obtained at Beijing Synchrotron Radiation Facility (BSRF).  相似文献   
9.
本研究用酶联免疫吸附术观察8只家兔在附睾注射鱼肝油酸钠后血清及精浆中的抗精子抗体。血清抗精子抗体阳性率为37.5~50.0%,最早检出率为术后2个月,6~7月达高峰。精浆抗精子抗体阳性率为25%,最早检出率为术后4个月,且此时己达高峰。与输精管结扎资料相比,发现血清抗精子抗体检出率偏低,而精浆相应抗体偏高,表明向附睾注射鱼肝油酸钠引起的免疫反应有别于结扎,以生殖道局部为主。  相似文献   
10.
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