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   975篇
  免费   62篇
  国内免费   10篇
耳鼻咽喉   1篇
儿科学   34篇
妇产科学   16篇
基础医学   117篇
口腔科学   18篇
临床医学   64篇
内科学   277篇
皮肤病学   7篇
神经病学   68篇
特种医学   26篇
外科学   189篇
综合类   7篇
预防医学   76篇
眼科学   49篇
药学   60篇
中国医学   3篇
肿瘤学   35篇
  2023年   14篇
  2022年   21篇
  2021年   42篇
  2020年   18篇
  2019年   37篇
  2018年   47篇
  2017年   18篇
  2016年   23篇
  2015年   26篇
  2014年   52篇
  2013年   50篇
  2012年   77篇
  2011年   63篇
  2010年   44篇
  2009年   34篇
  2008年   62篇
  2007年   40篇
  2006年   56篇
  2005年   46篇
  2004年   51篇
  2003年   53篇
  2002年   46篇
  2001年   8篇
  2000年   15篇
  1999年   15篇
  1998年   5篇
  1997年   2篇
  1996年   6篇
  1995年   6篇
  1994年   3篇
  1993年   3篇
  1992年   7篇
  1991年   7篇
  1990年   5篇
  1989年   3篇
  1988年   2篇
  1987年   5篇
  1986年   4篇
  1985年   4篇
  1984年   3篇
  1981年   4篇
  1980年   1篇
  1979年   2篇
  1978年   3篇
  1977年   4篇
  1976年   1篇
  1974年   2篇
  1973年   2篇
  1971年   2篇
  1968年   2篇
排序方式: 共有1047条查询结果,搜索用时 15 毫秒
1.
A brief mechanical or electrical stimulus to peripheral nerve afferents from the upper and lower limbs elicited a small and inconsistent EMG response of the orbicularis oculi muscles. This response was facilitated when the stimuli were delivered at fixed leading time intervals, of 45–300 ms, with respect to a supraorbital nerve electrical stimulus. Also, the peripheral nerve stimulus modified the conventional blink reflex responses, inducing facilitation of R1 and inhibition of R2. These results suggest a complex processing of sensory inputs from the face and the limbs at the brainstem, where they are probably integrated in a network of interneurons influencing the excitability of facial motoneurons.  相似文献   
2.
3.
4.
This report describes a new species of aspidoderid nematode, Ansiruptodera scapteromi sp. nov., the second species to be reported in the genus Ansiruptodera Skrjabin and Shikhobalova, 1947. The A. scapteromi sp. nov. is the first species of the genus to be recorded from a rodent host. The new species is clearly different from the only other species, A. ansirupta (Proença, 1937) Skrjabin and Shikhobalova, 1947, in that it possesses short lateral alae that terminate before the midbody; a smaller cephalic extremity; a shorter esophagus, pharynx, tail, and tail appendage; a smaller sucker; and longer spicules. The two species also differ in the numbers and arrangements of caudal papillae. A. scapteromi appears to be a parasite of capture and the water rats seem to have been infected from Edentata in Uruguay.  相似文献   
5.
6.
7.
Eighteen children with severe head injuries and diffuse brain swelling were studied. They were separated into two groups based on the computed tomography (CT) findings. Seven patients had small ventricles in the normal location and small or absent cisterns. Eleven had these signs plus small deep-seated intraparenchymal hemorrhagic foci and/or intraventricular hemorrhage. Patients in the first group were in relatively good neurological condition; their intracranial pressure was easily controlled and all had a favourable outcome. On contrast, children in the second group had a more severe clinical presentation, frequently had uncontrollable intracranial hypertension, and more than 50% died.  相似文献   
8.
PURPOSE: To determine whether sequence analysis of 16S ribosomal DNA (rDNA) can be used to detect bacterial pathogens in patients with postoperative endophthalmitis. METHODS: In 10 eyes of 10 patients, vitreous specimens were collected for culture and rDNA typing. Variable segments of each ribosomal DNA specimen were amplified by polymerase chain reaction (PCR), sequenced, and aligned by BLAST, a computer alignment program, against sequences in GenBank at the National Institutes of Health. RESULTS: Specimens were available from five eyes with bacterial endophthalmitis diagnosed by Gram stain or culture. Amplified 16s rDNA sequences from the eyes of three patients were identical to microbiologic results. Polymerase chain reaction results were negative in two cases in which unusual organisms were detected. All five control specimens from patients with nonbacterial endophthalmitis or uveitis were PCR negative. Approximately 48 to 72 hours are required under ideal conditions for final species identification with this ribosomal typing technique. CONCLUSIONS: 16S rDNA typing shows potential as a relatively rapid technique for identifying bacteria in vitreous samples.  相似文献   
9.
BACKGROUND/AIMS: The World Health Organisation has recommended repeated mass treatment of children in trachoma endemic areas with oral azithromycin. While chlamydia, the causative agent of trachoma, remains universally sensitive to azithromycin, there is concern that large scale programmes may alter the bacterial flora and induce resistance in streptococcal species. In this study the effect of a single dose of azithromcyin on the prevalence, species distribution, and resistance of conjunctival bacterial flora was determined. METHODS: Baseline and 14 day follow up bacterial cultures were taken from the conjunctivae of 121 children who reside in a trachoma endemic area of Nepal. 91 children were treated with azithromycin at baseline and 31 children received deferred treatment at the 14 day follow up. RESULTS: Although the prevalence of bacterial pathogens decreased significantly with azithromycin treatment, a significant change in the distribution of specific bacterial pathogens could not be demonstrated. Streptococcal resistance to azithromycin was found significantly more frequently after treatment. No change in the prevalence, distribution, or resistance pattern was found in the untreated control group. CONCLUSION: Repeated mass treatment of trachoma endemic areas with oral azithromycin will have an effect on bacterial flora. However, further work needs to be done to determine if this will have any clinical relevance.  相似文献   
10.
Progress in biostatistics and epidemiology during twentieth century contributed to clinical research development. Controversy about the real role of these disciplines in validating clinical activity isn't new: in history of medicine there are evidence since nineteenth century. Evidence-based medicine is a recent methodology to evaluate clinical investigation that begins to be considered gold standard in knowledge and medical practice evaluation. Its method is based mainly in systematized meta-analyses or revisions through which tries to offer answers to concrete clinical questions. These answers are, however, clearly of statistical nature. It is not useful in clinical practice but rather should be focused to teaching-learning process, as well as on the creation of work regulations. Its application implies certain benefits, but also several practical difficulties in cultural, academic and socio-economic fields, due to its use without discriminating. Thus, its correct use is a challenge to contemporary medicine.  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