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   29221篇
  免费   1769篇
  国内免费   1107篇
耳鼻咽喉   1020篇
儿科学   616篇
妇产科学   96篇
基础医学   1526篇
口腔科学   3528篇
临床医学   2805篇
内科学   4650篇
皮肤病学   35篇
神经病学   1501篇
特种医学   1922篇
外国民族医学   1篇
外科学   7010篇
综合类   4092篇
现状与发展   2篇
预防医学   535篇
眼科学   233篇
药学   1184篇
  14篇
中国医学   993篇
肿瘤学   334篇
  2024年   95篇
  2023年   558篇
  2022年   876篇
  2021年   1183篇
  2020年   1174篇
  2019年   1051篇
  2018年   1072篇
  2017年   905篇
  2016年   1000篇
  2015年   1080篇
  2014年   2153篇
  2013年   1935篇
  2012年   1746篇
  2011年   1859篇
  2010年   1589篇
  2009年   1450篇
  2008年   1328篇
  2007年   1380篇
  2006年   1297篇
  2005年   1079篇
  2004年   919篇
  2003年   829篇
  2002年   682篇
  2001年   561篇
  2000年   483篇
  1999年   478篇
  1998年   398篇
  1997年   351篇
  1996年   292篇
  1995年   294篇
  1994年   263篇
  1993年   249篇
  1992年   212篇
  1991年   156篇
  1990年   128篇
  1989年   134篇
  1988年   114篇
  1987年   100篇
  1986年   94篇
  1985年   109篇
  1984年   83篇
  1983年   37篇
  1982年   76篇
  1981年   58篇
  1980年   54篇
  1979年   38篇
  1978年   29篇
  1977年   18篇
  1976年   18篇
  1973年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
The association of craniosynostosis with ectopia lentis is extremely rare. This was recently reported in monozygotic twin sisters, supporting a genetic etiology for this syndromic association. We report on female first cousins once removed who were born with unilateral coronal synostosis. One cousin also had peripheral pulmonic branch stenosis at birth and was later found to have ectopia lentis and severe myopia. The other cousin had an atrial septal defect, mitral valve prolapse, and only mild myopia. Their intelligence is normal. The inheritance is likely autosomal dominant with variable expression and incomplete penetrance and further defines this syndrome to include congenital heart defects. These findings will have important implications for genetic counseling. © 2001 Wiley‐Liss, Inc.  相似文献   
142.
目的 总结并分析上颌第一恒磨牙根管治疗的临床疗效。方法 对151颗上颌第一桓磨牙患牙进行根管治疗并观察疗效。结果 151例患牙完成根管充填136颗;治愈率为90.07%。共检出四根管32颗,检出率为21.19%。结论 熟悉髓室和根管的解剖形态,正确的根管预备,严密的根管充填,是提高上颌第一恒磨牙根管治疗疗效的必要条件。  相似文献   
143.
面神经管及其定位的研究   总被引:3,自引:0,他引:3  
本文对80侧颞骨标本研究结果表明,面神经在内耳道、迷路段、水平段和垂直段的长度((?)±SD,mm)成人分别为:12.30±2.47、3.84±0.58、9.95±3.16、11.88±2.37;儿童为11.21±2.27、3.75±1.11、9.66±1.34、11.67±1.75,同时还观测了面神经管与周围结构的关系,为 Bell 面瘫减压术和面神经修补术提供了形态学依据。  相似文献   
144.
The aim of this study was to determine the diagnostic accuracy of technetium-99m tetrofosmin myocardial imaging for the localization of coronary artery stenoses of different degrees of severity. Stress-rest single-photon emission tomography (SPET) was performed on separate days in 80 patients (64 males, 16 females; mean age 61 years; 43 patients with previous myocardial infarction; 18 patients with pharmacological stress), within 6 months of coronary angiography. Scintigraphic images were blindly and independently evaluated by three observers. Coronary stenosis was defined as a >50% narrowing in luminal diameter; severe stenosis was defined as a proximal stenosis of >75% or a peripheral stenosis of >90%. Coronary angiography revealed normal coronary arteries or insignificant coronary stenosis in 13 patients and significant coronary stenoses in 67 patients. The sensitivity and specificity of 99mTc-tetrofosmin SPET in respect of severely stenosed vessels were, respectively, 80% and 65% for the left anterior descending artery (LAD), 100% and 46% for the right coronary artery (RCA) and 58 and 78% for the left circumflex artery (LCx) territories. Considering all the significantly stenosed vessels, a significant decrease in sensitivity was observed for LAD territories (to 59%, P=0.05), and a nonsignificant decrease for RCA (88%) and LCx (47%) territories while specificity values remained essentially unchanged. No significant changes in sensitivity or specificity were observed when regions with previous myocardial infarction were excluded. In conclusion, the sensitivity of 99mTc-tetrofosmin SPET for the localization of individual stenosed vessels is only moderate when all significant stenoses are considered, but the ability of this technique to predict the location of severe coronary artery stenoses seems satisfactory, with the exception of the low specificity in respect of RCA territories. Received 26 April and in revised form 7 June 1997  相似文献   
145.
Traditional experimental methods are unable to study the kinematics of whole lumbar spine specimens under physiologic compressive preloads because the spine without active musculature buckles under just 120 N of vertical load. However, the lumbar spine can support a compressive load of physiologic magnitude (up to 1200 N) without collapsing if the load is applied along a follower load path. This study tested the hypothesis that the load-displacement response of the lumbar spine in flexion-extension is affected by the magnitude of the follower preload and the follower preload path. Twenty-one fresh human cadaveric lumbar spines were tested in flexion-extension under increasing compressive follower preload applied along two distinctly different optimized preload paths. The first (neutral) preload path was considered optimum if the specimen underwent the least angular change in its lordosis when the full range of preload (0-1200 N) was applied in its neutral posture. The second (flexed) preload path was optimized for an intermediate specimen posture between neutral and full flexion. A twofold increase in flexion stiffness occurred around the neutral posture as the preload was increased from 0 to 1200 N. The preload magnitude (400 N and larger) significantly affected the range of motion (ROM), with a 25% decrease at 1200 N preload applied along the neutral path. When the preload was applied along a path optimized for an intermediate forward-flexed posture, only a 15% decrease in ROM occurred at 1200 N. The results demonstrate that whole lumbar spine specimens can be subjected to compressive follower preloads of in vivo magnitudes while allowing physiologic mobility under flexion-extension moments. The optimized follower preload provides a method to simulate the resultant vector of the muscles that allow the spine to support physiologic compressive loads induced during flexion-extension activities.  相似文献   
146.
Abstract This study was undertaken to elucidate the pathogenesis of the hydrocephalus and aqueductal stenosis induced by intracerebral mumps virus inoculation in suckling hamsters.
Mild ventricular dilatation became apparent after 5 days of inoculation. Focal denuding of the ependymal layer and subsequent aqueductal stenosis were observed by 14 days after inoculation. The virus antigen was detected not only in the ependymal cells and choroid plexus, but also in some neurons in the cerebral cortex, hippocampus, midbrain and cerebellum. In the cerebral aqueduct, the orderly arrangement of the cilialy clusters was destroyed on the 5th day after inoculation. After 10 days, proliferation of GFAP positive cells was noticed around the cerebral aqueduct and subsequently caused aqueductal stenosis. In the advanced state of hydrocephalus, the cerebellum was displaced downward and showed an elongated, atrophic and sleevelike structure similar to the Arnold-Chiari malformation. It was suggested that the extensive damage of the ependymal cilia may account for early ventricular dilatation, and subsequent aqueductal stenosis with glial proliferation is the main cause of the advanced hydrocephalus. It has not yet been determined whether the mumps virus can pass through the human placenta or not. If it can, however, our results strongly suggest that mumps virus infection in the human fetus will cause congenital hydrocephalus.  相似文献   
147.
Percutaneous transvenous mitral commissurotomy was performed successfully via the transjugular approach in a patient with severe rheumatic mitral stenosis and obstruction of the inferior vena cava due to prior liver transplantation. This case demonstrates the advantage of the jugular approach in patients with difficult anatomy.  相似文献   
148.
In this report, we give details of two families in which fixed subaortic stenosis was found in more than one member. It is rare for this entity to show familial incidence.  相似文献   
149.
BACKGROUND: Common carotid artery (CCA) volume flow rate (VFR) is clinically useful for study of cerebrovascular disease. Color Velocity Imaging Quantification (CVI-Q; Philips Ultrasound International, Irvine, CA), previously reported as accurate and reliable, tracks the flow lumen over the cardiac cycle, as well as mean spatial velocity, which is multiplied by vessel area to obtain VFR. VFR can also be obtained by Doppler sampling for mean velocity, and vessel area based on static B-mode lumen diameter. We compared CCA VFR by CVI-Q and Doppler method (DM), since knowledge of how they compare is crucial when both are used clinically. METHOD: We prospectively studied patients having clinical carotid duplex exams and healthy controls. All had CCA VFR measured by both methods in the same exam session. RESULTS: Thirty-four studies were reviewed. CCA VFR by CVI-Q in those without ICA stenosis was 337 +/- 96 mL/m, and by DM 359 +/- 130 mL/m; P = .33. There was no difference between methods for 50-75% or 75-95% ICA stenosis. In 7 patients with ICA occlusion, and 3 with 95-99% stenosis, VFR was higher by DM than by CVI-Q (Occlusion: 125 vs 58 mL/m, P = .007; 95-99%: 152 vs 63 mL/m, P = .038). There was no statistically significant difference between methods for measurement of the ratio of VFR between right and left CCA. CONCLUSION: In patients with 0-95% ICA stenosis, VFR by CVI-Q and DM showed no difference. For 95-100% ICA stenosis the methods differ; with higher VFR by DM. Side-to-side VFR ratios remain constant, irrespective of VFR method, and can still provide clinically useful information.  相似文献   
150.
目的总结分析伴有马尾神经损害的腰椎间盘突出症的临床特点,并对手术方法进行探讨.方法对采用撑开式椎板成形术治疗的26例伴有马尾神经损害的腰椎间盘突出症患者的临床资料进行回顾性分析.结果获得随访资料26例平均随访6年5个月,根据Macnab疗效标准,优17例,良7例,可1例,差1例.优良率92.3%.结论伴有马尾神经损害的腰椎间盘突出症的临床症状重,手术治疗需要彻底减压方能取得优良效果.采用撑开式椎板成形术显露,除具有全椎板切除的优点,还不破坏腰椎后柱的稳定性,最大限度地保留了脊柱的完整性,减小了手术创伤,是行之有效的手术方法.  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