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   21268篇
  免费   2018篇
  国内免费   97篇
耳鼻咽喉   269篇
儿科学   670篇
妇产科学   417篇
基础医学   2414篇
口腔科学   1324篇
临床医学   1885篇
内科学   4850篇
皮肤病学   589篇
神经病学   1288篇
特种医学   653篇
外国民族医学   4篇
外科学   3349篇
综合类   703篇
一般理论   17篇
预防医学   1326篇
眼科学   526篇
药学   1576篇
中国医学   112篇
肿瘤学   1411篇
  2024年   18篇
  2023年   266篇
  2022年   816篇
  2021年   1233篇
  2020年   717篇
  2019年   987篇
  2018年   1168篇
  2017年   779篇
  2016年   884篇
  2015年   818篇
  2014年   1060篇
  2013年   1329篇
  2012年   1587篇
  2011年   1686篇
  2010年   973篇
  2009年   758篇
  2008年   1046篇
  2007年   1036篇
  2006年   921篇
  2005年   924篇
  2004年   876篇
  2003年   706篇
  2002年   669篇
  2001年   248篇
  2000年   211篇
  1999年   190篇
  1998年   146篇
  1997年   92篇
  1996年   92篇
  1995年   94篇
  1994年   62篇
  1993年   55篇
  1992年   59篇
  1991年   60篇
  1990年   61篇
  1989年   66篇
  1988年   68篇
  1987年   76篇
  1986年   76篇
  1985年   57篇
  1984年   54篇
  1983年   40篇
  1982年   26篇
  1981年   37篇
  1980年   23篇
  1979年   27篇
  1978年   17篇
  1977年   22篇
  1975年   19篇
  1974年   13篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
Brain nerve growth factor (NGF) was determined in two groups of aged rats: 'good' and 'poor' performers. The animals were selected out of a population of 40 aged rats (26-28 months old) trained in a spatial learning task. Animals performing well in the test had significantly higher NGF in the hippocampus when compared to 'poor' performers. No differences in the levels of NGF were found in the cortex, septum and cerebellum. The results implicate hippocampal NGF in cognitive functioning of aged rats, and suggests that the forebrain cholinergic neuronal atrophy which has been observed in cognitively impaired aged rats may be due to reduced availability of target-derived NGF.  相似文献   
72.

Background  

Veno-arterial extracorporeal membrane oxygenation (ECMO) is a common modality of circulatory assist device used in children. We assessed the outcome of children who had ECMO following repair of congenital cardiac defects (CCD) and identified the risk factors associated with hospital mortality.  相似文献   
73.
74.
BACKGROUND & AIMS: Even though propofol has better recovery profile than traditional agents, its use is limited because of the perception of increased complication rates. Because an adequately powered trial comparing risk of propofol with traditional agents is lacking, we performed a meta-analysis of the current literature. METHODS: We searched Medline (1966-October 2004), EMBASE (1980-October 2004), and Cochrane controlled trials registry. The following 4 cardiopulmonary complications were assessed: hypoxia, hypotension, arrhythmias, and apnea. Procedures were divided into 3 groups: esophagogastroduodenoscopy group, colonoscopy group, and endoscopic retrograde cholangiopancreatography/endoscopic ultrasonography group. Pooled odds ratios for complications were calculated for all the procedures combined and then separately for the 3 groups. Random effects models were used for 2-proportion comparisons. RESULTS: Of the 90 citations identified, 12 original studies qualified for this meta-analysis and included 1161 patients. Of these, 634 received propofol, and 527 received midazolam, meperidine, and/or fentanyl. Most of the included studies were randomized trials of moderate quality and nonsignificant heterogeneity (Cochran Q = 4.81, P = .90). Compared with traditional sedative agents, the pooled odds ratio with the use of propofol for developing hypoxia or hypotension for all the procedures combined was 0.74 (95% confidence interval [CI], 0.44-1.24); for EGD, 0.85 (95% CI, 0.33-2.17); for colonoscopy, 0.4 (95% CI, 0.2-0.79); and for ERCP/EUS, 1.07 (95% CI, 0.38-3.01). CONCLUSIONS: Propofol sedation during colonoscopy appears to have lower odds of cardiopulmonary complications compared with traditional agents, but for other procedures, the risk of complications is similar.  相似文献   
75.
目的在背根神经节(dorsal root ganglion,DRG)中等大小感觉神经元中可以观察到钙激活氯离子流(I_(Cl(Ca)))。在坐骨神经损伤模型中,在大多数大中神经元上诱导出类似的氯离子流。本文旨在探讨引起这个离子流的分子基础。方法使用常规的定量RT-PCR方法检测在DRG中三个基因家族的表达,这三个基因家族都具有诱导I_(Cl(Ca))的特点。结果在成年小鼠的DRG中,分别显示了在正常状态和坐骨神经损伤3天后CLCA,Bestrophin和Tweety基因家族成员的转录产物。结论mBestl和Tweety2可能在损伤诱导的DRG神经元I_(Cl(Ca))中发挥作用。  相似文献   
76.
OBJECTIVE: The purpose of this retrospective analysis was to determine the pain associated with needle insertion, placement, and solution deposition for the conventional inferior alveolar nerve (IAN) block in patients with irreversible pulpitis. STUDY DESIGN: One hundred two emergency patients with irreversible pulpitis received IAN block injections using 2% lidocaine with 1:100,000 epinephrine. The patients recorded pain of the 3 injection stages on a Heft-Parker visual analog scale (VAS). RESULTS: Moderate-to-severe pain may occur 57% to 89% of the time with the IAN block. Needle placement was significantly more painful than needle insertion for men and significantly more painful than either insertion or deposition for women (P < .03). There was no statistical difference between the pain for men or women with respect to needle insertion, placement, or deposition pain (P > .05). Deposition of 0.2 to 0.4 mL anesthetic during placement did not significantly reduce placement pain for either gender (P = .753). CONCLUSION: In conclusion, 57% to 89% of patients presenting with irreversible pulpitis have the potential for moderate to severe pain with the IAN block.  相似文献   
77.
78.
A rare case of congenital lumbar hernia associated with carpus equina varus is described in a week old baby. The treatment is described with limited review of the literature.  相似文献   
79.
Despite recent advances in surgical technique using laparoscopic and robotic approaches for the management of early organ-confined prostate cancer, most contemporary reports demonstrate significant rates of erectile dysfunction comparable to standard open approaches. Controversy remains related to many of the pre-and postoperative management strategies, including agents to enhance nerve recovery, erectogenic drugs, antioxidants, vasoactive injectables, vacuum erection devices and nerve grafting procedures. Additionally, the optimal timing of these interventions and their duration, dose, frequency and outcome thresholds remain ill-defined. In our paper, we provide a comprehensive literature review involving both the basic and clinical data surrounding rehabilitative approaches.  相似文献   
80.
OBJECTIVE: The prevalence of child psychiatric morbidity in the community is unknown in most developing countries, including those in the Arab region. METHOD: An epidemiologic study was carried out to estimate the prevalence of psychiatric morbidity and to determine the sociodemographic correlates in a sample of children in the community, aged 6 to 18 years, in A1 Ain, United Arab Emirates (UAE). RESULTS: We obtained a prevalence rate of 22.2% for overall morbidity, as classified in the DSM-1V, and 14.3% for those with significant dysfunction, with the most common diagnosis being mood disorders. Female sex, large family size, chronic life difficulties, family history of psychiatric disorder, and alcohol-related problems in a family member were significantly associated with DSM-IV diagnosis. CONCLUSION: Although the prevalence and symptomatology in this Middle East community are similar to those in Western studies, none of these children had received professional help, suggesting serious deficiencies in mental health care services in the country.  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