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   5455篇
  免费   364篇
  国内免费   10篇
耳鼻咽喉   91篇
儿科学   195篇
妇产科学   131篇
基础医学   815篇
口腔科学   94篇
临床医学   506篇
内科学   1160篇
皮肤病学   144篇
神经病学   436篇
特种医学   375篇
外科学   651篇
综合类   51篇
预防医学   443篇
眼科学   123篇
药学   324篇
中国医学   6篇
肿瘤学   284篇
  2021年   50篇
  2020年   46篇
  2019年   57篇
  2018年   90篇
  2017年   50篇
  2016年   83篇
  2015年   103篇
  2014年   128篇
  2013年   187篇
  2012年   228篇
  2011年   226篇
  2010年   153篇
  2009年   159篇
  2008年   229篇
  2007年   236篇
  2006年   233篇
  2005年   219篇
  2004年   196篇
  2003年   215篇
  2002年   209篇
  2001年   185篇
  2000年   206篇
  1999年   175篇
  1998年   98篇
  1997年   78篇
  1996年   60篇
  1995年   65篇
  1994年   55篇
  1993年   61篇
  1992年   99篇
  1991年   94篇
  1990年   105篇
  1989年   109篇
  1988年   101篇
  1987年   80篇
  1986年   86篇
  1985年   81篇
  1984年   50篇
  1983年   57篇
  1981年   41篇
  1980年   37篇
  1979年   65篇
  1978年   48篇
  1977年   43篇
  1975年   41篇
  1974年   40篇
  1973年   59篇
  1972年   51篇
  1970年   38篇
  1969年   37篇
排序方式: 共有5829条查询结果,搜索用时 0 毫秒
991.
992.
Neither macroscopic nor microscopic lesions were observed in the gastrointestinal mucosa following the surgical removal of Brunner's glands. This observation leaves some doubt concerning the traditional view that Brunner's glands function primarily in the protection of the proximal duodenal mucosa from acid-pepsin entering from the stomach.  相似文献   
993.
Development of the pituitary in Didelphis follows the general pattern of that described for most mammalian species. The dorsal region of a multichambered pituitary vesicle, which forms from Rathke's pouch, comes to lie adjacent to the presumptive infundibulum by the 10 1/2 d of gestation. The epithelial wall of this vesicle consists of spindle-shaped cells. The dorsal wall of the upper chamber of the pituitary vesicle forms the pars intermedia; the ventral wall of this chamber gives rise to cells of the pars distalis. Corticotropes, somatotropes, and lactotropes are seen in the presumptive adenohypophysis of the 11 1/2 d embryo. Gonadotropes and thyrotropes appear about 1 d later, shortly after birth. By the 2 postnatal week, the adult distribution of all 5 cell types within the pars distalis appears to have been established. The wall bounding the pituitary cleft in the adult represents an epithelial continuum limited by a basal lamina and corresponds to the upper chamber of the original pituitary vesicle. Ultrastructurally, the limiting walls of the pituitary cleft consists of stellate (marginal) cells, large, bulbous cells, and granulated cells. The latter correspond to the various endocrine cell types normally associated with the pars distalis. Non-granular folliculo-stellate cells also are observed within the epithelial cords of the pars distalis.  相似文献   
994.
Summary The aim of the study was to investigate the influence of 40 mg of the beta-blocker penbutolol (BetapressinTM; Hoechst Ltd., Frankfurt/ Main) in comparison to placebo on the insulin consumption on the blood sugar profile in twelve insulin-dependent diabetes (IDDM) patients. The patients were treated with penbutolol and placebo for a period of three days, and then were examined with the help of the glucose-controlled insulin infusion system.The blood sugar profile and insulin consumption over a 24 hour period was not affected by either penbutolol or placebo, nor could any changes be measured in these parameters when measured after food intake.After a submaximal exercise load on the bicycle ergometer (1 watt per kg body weight) following an evening meal, no difference could be observed between penbutolol and placebo in the above-mentioned parameters. The same was also true for hormonal parameters as STH, ACTH, cortisol, and catecholamines.These findings demonstrated that medication of penbutolol over a three-day period has no influence on the baseline blood sugar profile and insulin consumption or on insulin consumption after food intake during rest and physical exercise.Abbreviations IDDM insulin-dependent diabetes - STH somatotropic hormone - GH growth hormone - ACTH adrenocorticotropic hormone - HbA1 glycosylated hemoglobin A1 - mE milli-units - SEM standard error of the mean  相似文献   
995.
996.
997.
998.

Background

Data on paediatric deep brain stimulation (DBS) is limited, especially for long-term outcomes, because of small numbers in single center series and lack of systematic multi-center trials.

Objectives

We seek to systematically evaluate the clinical outcome of paediatric patients undergoing DBS.

Methods

A German registry on paediatric DBS (GEPESTIM) was created to collect data of patients with dystonia undergoing DBS up to the age of 18 years. Patients were divided into three groups according to etiology (group 1 inherited, group 2 acquired, and group 3 idiopathic dystonia).

Results

Data of 44 patients with a mean age of 12.8 years at time of operation provided by 6 German centers could be documented in the registry so far (group 1 n = 18, group 2 n = 16, group 3 n = 10). Average absolute improvement after implantation was 15.5 ± 18.0 for 27 patients with pre- and postoperative Burke-Fahn-Marsden Dystonia Rating scale movement scores available (p < 0.001) (group 1: 19.6 ± 19.7, n = 12; group 2: 7.0 ± 8.9, n = 8; group 3: 19.2 ± 20.7, n = 7). Infection was the main reason for hardware removal (n = 6). 20 IPG replacements due to battery expiry were necessary in 15 patients at 3.7 ± 1.8 years after last implantation.

Discussion

Pre- and postoperative data on paediatric DBS are very heterogeneous and incomplete but corroborate the positive effects of DBS on inherited and acquired dystonia. Adverse events including relatively frequent IPG replacements due to battery expiry seem to be a prominent feature of children with dystonia undergoing DBS. The registry enables collaborative research on DBS treatment in the paediatric population and to create standardized management algorithms in the future.  相似文献   
999.
The purpose of this study was to compare dye leakage in the dentin of resected and nonresected roots. Fifty-four single rooted extracted teeth were used. The two groups were subdivided into young, middle age, and old age samples. Each sample was biomechanically prepared in a standard fashion and obturated using lateral condensation with sealer and gutta-percha. All root surfaces were sealed with nail polish, leaving the apical portion exposed. The apical portion of the roots were placed in 2% methylene blue dye for 72 h, rinsed, and placed in 15 ml of 35% HNO3 for 72 h. The supernatant was analyzed at 640 nm using a visible light spectrophotometer. The amount of leakage was extrapolated from a standard linear regression curve constructed from the stock 2% methylene blue dye solution. The percentage of concentration leakage in all samples ranged from less than 0.0600 to 0.1658. It was concluded that there is a greater amount of leakage in resected versus nonresected extracted teeth. The data also suggest that older teeth exhibit less leakage than younger teeth.  相似文献   
1000.
Combination of mannan antigen and anti‐mannan antibody (Mn/A‐Mn) testing has been reported a useful and specific strategy for diagnosis of invasive Candida infections (ICIs). We evaluated Mn/A‐Mn as a screening tool in patients with haematological malignancies. This clinical prospective study was performed at the Division of Hematology, Medical University Graz, Austria between July and December 2012. Patients at risk for fungal infection were included into the study and twice weekly screened by Mn/A‐Mn testing, yielding 650 samples. Of overall 67 patients 66 had no evidence for ICI. From those, 153/640 serum samples (23.9%) were positive for mannan Ab, and nine (1.4%) for Ag. Most false positive Ab results were observed among 375 samples from patients without haematopoietic stem cell transplantation (34.9% resulted positive). Combined specificity of Mn/A‐Mn was 74.8%. Of 10 samples obtained in the single patient with candidemia, five were positive for mannan Ag (from the day of diagnosis up to 40 days after detection of candidemia) and none for Ab. In conclusion, mannan Ab screening yielded a high number of false positive results. While mannan Ag was found to be highly specific and may have potential for diagnostic driven testing, mannan Ab testing cannot be recommended based on our study results.  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