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   2099603篇
  免费   161522篇
  国内免费   4175篇
耳鼻咽喉   29600篇
儿科学   72679篇
妇产科学   59036篇
基础医学   301311篇
口腔科学   57924篇
临床医学   188979篇
内科学   410952篇
皮肤病学   46700篇
神经病学   165820篇
特种医学   82662篇
外国民族医学   941篇
外科学   318270篇
综合类   47497篇
现状与发展   1篇
一般理论   754篇
预防医学   163576篇
眼科学   47684篇
药学   154071篇
  7篇
中国医学   4042篇
肿瘤学   112794篇
  2018年   21938篇
  2017年   16845篇
  2016年   18751篇
  2015年   21248篇
  2014年   29354篇
  2013年   45031篇
  2012年   60765篇
  2011年   64554篇
  2010年   38615篇
  2009年   36443篇
  2008年   61184篇
  2007年   65244篇
  2006年   65862篇
  2005年   63778篇
  2004年   62208篇
  2003年   59976篇
  2002年   58587篇
  2001年   99288篇
  2000年   102441篇
  1999年   86706篇
  1998年   24399篇
  1997年   21894篇
  1996年   22184篇
  1995年   21283篇
  1994年   19953篇
  1993年   18531篇
  1992年   69151篇
  1991年   67751篇
  1990年   66071篇
  1989年   63383篇
  1988年   58139篇
  1987年   57741篇
  1986年   53935篇
  1985年   51961篇
  1984年   39042篇
  1983年   32959篇
  1982年   19490篇
  1981年   17668篇
  1979年   35415篇
  1978年   25161篇
  1977年   21290篇
  1976年   19996篇
  1975年   21365篇
  1974年   25333篇
  1973年   24427篇
  1972年   22527篇
  1971年   20779篇
  1970年   19399篇
  1969年   17776篇
  1968年   16371篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
BACKGROUND: Levels of an immunoregulatory and anti-inflammatory cytokine IL-10 are reduced in asthmatic airways, potentially contributing to more intense inflammation. Triamcinolone has anti-inflammatory properties and the anti-inflammatory effects of montelukast and formoterol have been discussed. OBJECTIVE: The purpose of this study was to define the effect of treatment with triamcinolone, montelukast and formoterol on the serum level of IL-10, eosinophil blood counts, eosinophil cationic response (ECP) and clinical parameters (symptom score, FEV1 and PC20H) in children with moderate asthma. METHODS: An 8-week, placebo-controlled and randomized, double-blind trial was carried out. The subjects were 91 children with moderate atopic asthma who were allergic to dust mite. Patients were randomly allocated to receive 400 microg triamcinolone (n = 19), 5 or 10 mg (according to age) montelukast (n = 18), 24 microg formoterol (n = 18) or placebo (n = 36). RESULTS: Seventy-nine children completed the study. After treatment with triamcinolone and montelukast the level of IL-10 in blood serum significantly increased, eosinophil blood counts and ECP levels significantly decreased and all clinical parameters improved; treatment with formoterol had no effect on IL-10 level, eosinophil blood counts in serum and bronchial hyper-reactivity; ECP level significantly decreased after treatment and asthma symptoms and FEV1 improved significantly. Mean IL-10 levels in serum before and after treatment with triamcinolone were 7.23 pg/mL with 95% CI, 6.74 -7.72% and 14.24 pg/mL with 95% CI, 11.6-16.88%, respectively (P < 0.001); with montelukast they were 6.59 pg/mL with 95% CI, 6.26-7.23% and 10.94 pg/mL with 95% CI, 8.24-12.65%, respectively (P < 0.002); with formoterol they were 7.06 pg/mL with 95% CI, 6.61-7.52% and 7.04 pg/mL with 95% CI, 6.15-7.93%. We found statistically significant correlations between serum level of IL-10 and serum level of ECP after treatment with triamcinolone and montelukast. CONCLUSION: This study demonstrates that one possible way by which triamcinolone and montelukast contribute to inhibition of inflammation is by increasing IL-10 levels.  相似文献   
992.
The T-cell receptor (TCR) repertoire plays an important role in shaping specific immune responses. Genetic polymorphisms at the TCR locus, in both constant and variable regions, seem to represent an important mechanism for generating inter-individual and inter-population differences. Considering the scarcity of immune parameters characterized for normal human populations, we decided to determine the frequency of two TCRBV polymorphisms (located in the TCRBV3S1 and TCRBV18 gene segments) in two ethnically distinct groups of the general Brazilian population. Both polymorphisms are related to the expression of these segments at the T-cell surface and can consequently modulate the T-cell repertoire, potentially modifying the capacity of a given individual to develop an immune response. These DNA polymorphisms were analysed in material obtained from adult, normal South-American Caucasoid and Black individuals. A total of 139 individuals were analysed for the TCRBV3S1 and 141 for the TCRBV18 gene segment polymorphisms. The data indicated statistically significant differences in allelic frequencies for the two ethnic groups analysed, suggesting that any correlation between TCR usage or T-cell repertoire and development of a given disease should take in account the ethnic origin of the population studied.  相似文献   
993.
The morbidity and mortality conference (M&MC) appears to have sprung from the efforts of physicians to improve practice through the examination of medical errors and bad outcomes. The modern M&MC has had limited examination (and almost none outside surgery and anesthesia), but may be straying from the precepts from which it evolved. Learning from one's errors is important, but confronting them is difficult and is particularly delicate when done in conference. If the effort is successful, it can serve as a model. If unsuccessful, it can instead convey the lesson that attempting to learn from error is at best unproductive and at worst unpleasant. Thus, the M&MC is a double-edged sword, and particular attention should be given to the way that it is conducted. The authors review the historical roots and current literature on the M&MC, discusses relevant literature on medical error, and offers a definition, guiding principles, and a set of guidelines for a modern internal medicine M&MC. The ideas are presented not as a blueprint, but rather to stimulate a debate on the merits of establishing a framework for a working model, in order to refocus on the tradition of self-analysis and critical thinking in a manner that is productive for all participants.  相似文献   
994.
995.
The main point of this study resides in comparing the efficiency and the disadvantages of using cefazoline and cotrimoxazole in the prevention of post-surgery infections of the low urinary tract. 91 patients who were about to undergo urologic surgery were divided in three groups for randomisation. 31 patients received 500 mg of intramuscular cefazoline every eight hours, the day before surgery, the day of surgery and five days following surgery. 30 others received 800 mg of intramuscular sulfametoxazole and 160 mg of trimetoprime every 12 hours during the same lapse of time. The third group of 30 patients did not receive any antibiotics. Age, sex, clinical pathology needing surgery and indwelling catheter were the same in the three groups. The group treated by cefazoline, presented 5 post surgery infections among which 3 transitory fevers and 2 isolated bacteriurias. In the group treated by cotrimoxazole, there were 7 post surgery infections among which 3 fevers and 4 isolated bacteriurias. Tolerance in both cases was similar. In the control group, there were 19 post-surgery infections with 2 cases of sepsis, 14 transitory fevers and 3 isolated bacteriurias. These results show the importance of antibiotic prophylaxy in urologic surgery of the low genital tract whether the patient has a urethral catheter or not and whatever the type of urologic surgery. But, there is no significant difference between cefazoline and cotrimoxazole.  相似文献   
996.
997.
Summary In cases where a reconstruction of defects in the larynx, oral cavity, the pharynx or in the ear region has been performed using skin flaps, a temporary fistula is formed at the point of entry.This fistula can be closed later after the flap has taken and the flap pedicle dissected.We would like to demonstrate with some examples that with the use of deepithelisation it is possible to achieve a primary wound closure. This way no temporary fistula results and additional surgery is avoided in many cases.Furthermore flap deepithelisation offers a way to bring good vascularised tissue under the skin and cover subcutaneous defects, for example those after radiotherapy.

Die Veröffentlichung des Manuskripts soll in Laryngol Rhinol Otol (Stuttg) erfolgen  相似文献   
998.
The presence of accessory channels between the liver and extrahepatic bile ducts has long been recognised by anatomists and the division of such ducts may be a cause of bile leakage following cholecystectomy. However, visualisation of accessory bile ducts at operation is difficult as they are often small and sometimes less than 1 mm in diameter. Cholangiography has been used to help in the identification of accessory ducts in 50 patients included in a prospective trial. X-rays were taken after dissection of the gall bladder from its bed and extravasation of contrast was seen on five occasions (10%) suggesting leakage from divided accessory ducts. The identification of damage to accessory bile ducts in 10% of patients suggests that this may occur more frequently than previously supposed.  相似文献   
999.
Current trend in the treatment of Hodgkin's disease   总被引:1,自引:0,他引:1  
The analysis of three subsequent randomized trials carried out within the frame of the European Organization for Research on Cancer (E.O.R.T.C.) enables to define a strategy for the staging and the treatment of early stages of Hodgkin's disease. Several prognostic factors were identified by multivariate analyses: 1) erythrocyte sedimentation rate, which has a greater impact on relapse-free survival than systemic symptoms but which can be combined with them; the combination of the two is a more powerful prognostic indicator than ESR alone; 2) the number of involved lymphatic areas: patients with one or two lymphatic areas involved (CS I and II2) have a better outcome than stage II patients with 3 or more areas involved (CS II3). Patients with favorable prognostic indicators are submitted to staging laparotomy because for them spleen involvement has a pejorative impact. For patients with unfavorable indicators, the spleen involvement has little prognostic significance and therefore those patients who need, anyway, an aggressive treatment do not undergo staging laparotomy. Patients with favorable prognostic indicators and negative staging laparotomy can be treated by radiotherapy alone, patients with positive laparotomy or patients with unfavorable prognostic indicators are treated by combination of multiple chemotherapy and radiotherapy.  相似文献   
1000.
Summary The quantity of protein and carbohydrate comprising the matrix of calcium oxalate monohydrate (COM) renal stones was found to decrease with distance from the surface of the stone. The average organic concentration of stones 3 to 30 mm in diameter ranged from 5.7% at the surface to 2.7% at the core. This concentration gradient suggests matrix involvement in a “growth front” on stone surfaces with migration of organic material from the “older” interior. The matrix distribution was not readily correlated with density variations or with the presence of hydroxyapatite or calcium oxalate dihydrate. Surface matrix concentrations were greater than amounts predicted by physical adsorption. Electron microscopy confirmed the presence of the organic-rich surface layer and also suggested that increase in stone size occurs predominantly by crystal growth with microcrystal aggregates as growth centers.  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