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   12831篇
  免费   870篇
  国内免费   212篇
耳鼻咽喉   75篇
儿科学   189篇
妇产科学   84篇
基础医学   1460篇
口腔科学   313篇
临床医学   1704篇
内科学   1825篇
皮肤病学   91篇
神经病学   808篇
特种医学   903篇
外科学   1204篇
综合类   1417篇
一般理论   10篇
预防医学   1915篇
眼科学   146篇
药学   990篇
  6篇
中国医学   394篇
肿瘤学   379篇
  2024年   38篇
  2023年   301篇
  2022年   487篇
  2021年   670篇
  2020年   448篇
  2019年   485篇
  2018年   445篇
  2017年   471篇
  2016年   456篇
  2015年   492篇
  2014年   841篇
  2013年   1107篇
  2012年   739篇
  2011年   763篇
  2010年   650篇
  2009年   571篇
  2008年   575篇
  2007年   560篇
  2006年   470篇
  2005年   409篇
  2004年   407篇
  2003年   309篇
  2002年   244篇
  2001年   238篇
  2000年   186篇
  1999年   164篇
  1998年   152篇
  1997年   152篇
  1996年   127篇
  1995年   118篇
  1994年   108篇
  1993年   62篇
  1992年   83篇
  1991年   59篇
  1990年   60篇
  1989年   54篇
  1988年   63篇
  1987年   40篇
  1986年   44篇
  1985年   41篇
  1984年   43篇
  1983年   29篇
  1982年   25篇
  1981年   21篇
  1980年   23篇
  1979年   19篇
  1978年   16篇
  1977年   8篇
  1976年   14篇
  1973年   8篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
目的 探讨乳腺导管内乳头状瘤(intraductal papillomas,IP)癌变的临床表现、生物学行为、诊断、治疗及预后。方法 对1980年1月至2001年12月间7例IP癌变病人临床资料进行回顾性分析。结果 7例IP癌变占同期113例IP的5.19%,术前均未能确诊,5例术中冰冻考虑IP癌变。结论 IP有癌变潜能,其癌变者术前确诊困难,术中冰冻对诊断治疗意义重大,应重视术后随访。  相似文献   
62.
Clinical psychology is not as diverse as society, and the generalizability of clinical psychology to diverse groups has largely been untested. Some progress has been made in increasing the number of ethnic minorities receiving PhD degrees in clinical psychology and in increasing ethnic minority representation in clinical trials. Nevertheless, clinical psychologists and clinical psychology research are not diverse. A stages of change model may be useful in motivating clinical psychologists to diversify. A future scenario involving inertia and a second involving change are offered.  相似文献   
63.
The conceptual and methodological framework proposed by Doss (this issue) makes valuable suggestions for strategic choices in future research. This commentary addresses conceptual and terminological distinctions adopted by Doss, as well as his criticism of add-on/ dismantling studies. We also suggest research topics and methodological developments that could be integrated in Doss's framework to further expand understanding of therapeutic change.  相似文献   
64.
Objective To analyze the relationship between atrial fibrillation complicating long R-R interval, escape beat and escape heart rhythm and pathological atrioventricular block by dynamic electrocardiography (DCG). Methods 126 patients with atrial fibrillation were divided into group A (being related to sleep) and group B (being not related to sleep) according to the factor whether long R-R interval, escape beat and escape heart rhythm relevant to sleep. All were detected by DCG for 24 hours. Results The cases with1.5~2.0 s long R-R interval, more than 2.0s long R-R interval, escape beat and escape heart rhythm were (26.02±6.03), (7.39±1.05 ) and (6.90±1.28)in group A and (203.05±41.01), (35.48±7.52), (28.10±6.25) in group B respectively. The cases of group B were markedly more than those in group A. Conclusion Those atrial fibrillation complicating long R-R interval, escape bbeat and escape heart rhythm were related to sleep could not be deemed as pathological atrioventricular block, while those were not related to sleep could be considered pathological atrioventricular block.  相似文献   
65.
66.
BACKGROUND: Overall neocortical gray matter (NCGM) volume has not been studied in first-episode schizophrenia (FESZ) at first hospitalization or longitudinally to evaluate progression, nor has it been compared with first-episode affective psychosis (FEAFF). METHODS: Expectation-maximization/atlas-based magnetic resonance imaging (MRI) tissue segmentation into gray matter, white matter (WM), or cerebrospinal fluid (CSF) at first hospitalization of 29 FESZ and 34 FEAFF, plus 36 matched healthy control subjects (HC), and, longitudinally approximately 1.5 years later, of 17 FESZ, 21 FEAFF, and 26 HC was done. Manual editing separated NCGM and its lobar parcellation, cerebral WM (CWM), lateral ventricles (LV), and sulcal CSF (SCSF). RESULTS: At first hospitalization, FESZ and FEAFF showed smaller NCGM volumes and larger SCSF and LV than HC. Longitudinally, FESZ showed NCGM volume reduction (-1.7%), localized to frontal (-2.4%) and temporal (-2.6%) regions, and enlargement of SCSF (7.2%) and LV (10.4%). Poorer outcome was associated with these LV and NCGM changes. FEAFF showed longitudinal NCGM volume increases (3.6%) associated with lithium or valproate administration but without clinical correlations and regional localization. CONCLUSIONS: Longitudinal NCGM volume reduction and CSF component enlargement in FESZ are compatible with post-onset progression. Longitudinal NCGM volume increase in FEAFF may reflect neurotrophic effects of mood stabilizers.  相似文献   
67.
68.
三种内固定治疗上肢长骨干骨折的临床比较研究   总被引:4,自引:0,他引:4  
目的观察天鹅记忆接骨器(swan-likememoryconnector,SMC)治疗上肢长骨干骨折的疗效,并与加压接骨板(dynamiccompressiveplate,DCP)和带锁髓内针(lockedintramedullarynail,LIN)进行临床对比研究。方法随机选择1997年8月~2001年8月入院的新鲜上肢长骨干骨折148例,分别采用SMC(49例)与DCP(50例)、LIN(49例)进行内固定治疗,术后常规抗炎治疗1周,定期拍片并随访患肢功能恢复情况。结果SMC组的手术时间明显低于LIN组与DCP组(P<0.05),三组伤口感染率无差异。SMC组骨愈合时间和骨不连发生率显著短于DCP组和LIN组(P<0.05),而术后功能优良率高于DCP组和LIN组。在SMC固定下,骨折愈合直接由解剖型或类解剖型的骨样骨板状直接替代连接,固定段无应力遮挡和骨质疏松。结论SMC是治疗上肢长骨干骨折的有效方法,优于DCP和LIN。SMC的几何构形和力学特性有利于骨折愈合。在本器固定下,可能存在一种新的尚未被认知的骨折愈合方式。  相似文献   
69.
OBJECTIVE: The purpose of this laboratory study was to compare the frequency of failures (complete fractures or partial cracks) of molar crowns made of two different all-ceramic materials during dynamic loading in a chewing simulator, as well as the fracture load when subjected to static loading, in relation to different dynamic loading and luting protocols. METHODS: One hundred and forty-four molar crowns fabricated with IPS Empress or an experimental e.max Press material with high translucency (e.max Press Exp) were luted on CAD/CAM milled PMMA abutments (first lower molar, circular chamfer) either with Variolink or glass-ionomer cement (GIC). All crowns were loaded according to three different loading protocols (n=12 per group) and two force profiles (sinusoidal, rectangular) in a pneumatically driven chewing simulator with a steel stylus (? 8mm) and they underwent simultaneous thermocycling (5 degrees C/55 degrees C). After each phase the crowns were evaluated with regard to fractures or cracks. After dynamic testing, the crowns that did not fail were subjected to compression loading until complete fracture in a universal testing machine (UTM). As control groups, unloaded crowns were also subjected to a UTM. Survival statistics with log-rank tests were applied for the results of the dynamic loading, while ANOVA with post hoc Tukey B was used for the fracture load results and two-way ANOVA was carried out for logarithmically transformed data. Weibull statistics were calculated for pooled fracture load data of the dynamically loaded and control groups. RESULTS: In the 144 IPS Empress crowns, complete fractures were observed in 9 crowns and partial cracks in another 3 crowns. When the data was pooled, a statistically significant increase in fractures occurred when the sinusoidal force profile was applied compared to a rectangular force profile (log-rank, p<0.05). No fractures occurred in the e.max Press Exp crowns. The two-way ANOVA showed that the type of luting protocol used had the most significant effect on the fracture load of both materials. In conjunction with Empress, however, the luting material influenced the variability twice as much as in e.max Press Exp. There was no statistically significant difference in the fracture load of GIC-luted e.max Press Exp crowns and that of the Variolink luted Empress crowns. The force profile had a significant effect on the fracture load only of the Empress crowns but not of the e.max Press Exp crowns. Weibull statistics revealed a higher scattering of the data of dynamically loaded crowns compared to that of the control groups. CONCLUSIONS: For testing all-ceramic materials, dynamic loading is indispensable to draw valid conclusions on clinical performance of all-ceramic molar crowns. A sinusoidal profile is advisable, while a gradual increase of the force amplitude does not significantly affect the results.  相似文献   
70.
本文通过对3月龄、18月龄、24月龄雄性大鼠下丘脑去甲肾上腺素(NE)、多巴胺(DA)、5-羟色胺(5-HT)、5-羟吲哚乙酸(5-HIAA),和下丘脑垂体促甲状腺释放激素(TRH)、垂体、血甲状腺释放激素(TSH)、血甲状腺激素(T_3、T_4)的测定,研究了大鼠下丘脑神经递质与甲状腺轴机能的增龄性变化,并在此基础上探讨了补益中药对老龄大鼠下丘脑—垂体—甲状腺机能的作用。结果提示:老龄大鼠下丘脑机能的减退是甲状腺轴机能减退的重要原因;补益中药可能改善了老龄大鼠下丘脑的调控机能,进而延缓了甲状腺轴机能的老年性变化。  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