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   1769070篇
  免费   121212篇
  国内免费   3466篇
耳鼻咽喉   25740篇
儿科学   54741篇
妇产科学   49936篇
基础医学   260204篇
口腔科学   52160篇
临床医学   151540篇
内科学   338379篇
皮肤病学   40099篇
神经病学   136229篇
特种医学   68736篇
外国民族医学   494篇
外科学   272512篇
综合类   38152篇
现状与发展   6篇
一般理论   546篇
预防医学   126547篇
眼科学   41895篇
药学   134344篇
  4篇
中国医学   3803篇
肿瘤学   97681篇
  2018年   15915篇
  2015年   15605篇
  2014年   21788篇
  2013年   33329篇
  2012年   43982篇
  2011年   47196篇
  2010年   27905篇
  2009年   26818篇
  2008年   45271篇
  2007年   49312篇
  2006年   50044篇
  2005年   48401篇
  2004年   47142篇
  2003年   45584篇
  2002年   44976篇
  2001年   82005篇
  2000年   84613篇
  1999年   71222篇
  1998年   19145篇
  1997年   17330篇
  1996年   17036篇
  1995年   16003篇
  1994年   14982篇
  1992年   55307篇
  1991年   54637篇
  1990年   54168篇
  1989年   52695篇
  1988年   49066篇
  1987年   48359篇
  1986年   46159篇
  1985年   43966篇
  1984年   32937篇
  1983年   28032篇
  1982年   16561篇
  1981年   15165篇
  1980年   14155篇
  1979年   31886篇
  1978年   22958篇
  1977年   19794篇
  1976年   18284篇
  1975年   20944篇
  1974年   24802篇
  1973年   23812篇
  1972年   22991篇
  1971年   21642篇
  1970年   20355篇
  1969年   19572篇
  1968年   18359篇
  1967年   16524篇
  1966年   15201篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
Two cases of internal herniation through a defect in the broad ligament of the uterus are described. Both were successfully treated laparoscopically. This rare condition should be borne in mind when a middle-aged woman presents with colicky lower abdominal pain. The cause is unknown, but both congenital and acquired origins have been proposed. As far as emergency situations are concerned, laparoscopy has proven to be both a diagnostic and a therapeutic tool.  相似文献   
994.
OBJECTIVES: Local anaesthetic infiltration into the carotid sinus during carotid endarterectomy (CEA) has been recommended to minimise blood pressure fluctuations but its use remains controversial. The aim of this meta-analysis was to determine whether intra-operative administration of local anaesthetic reduces the incidence of haemodynamic instability following CEA. MATERIALS AND METHODS: A search of the Medline, Pubmed and Embase databases and the Current Controlled Trials register identified four trials, which met the pre-defined inclusion criteria for data extraction. Pooled odds ratios with 95 per cent confidence intervals (c.i.) for the development of post-operative hypotension and hypertension were calculated using a random-effects model. RESULTS: Outcomes of 432 patients were studied. Local anaesthetic blockade of the carotid sinus was associated with a pooled odds ratio of 1.25 (95 per cent c.i. 0.496 to 3.15); p=0.216) and 1.28 (95 per cent c.i. 0.699 to 2.33; p=0.428) for the development of post-operative hypotension and hypertension respectively. Although none reach significance there was a trend towards increased risk of developing a complication in those patients who received local anaesthetic. CONCLUSIONS: There are insufficient data to determine the role of intra-operative local anaesthetic administration in reducing post-operative blood pressure lability following CEA. Conversely, the possibility of harm cannot be excluded on the basis of the currently available data.  相似文献   
995.
By oxygen concentration measurements (Oximeter Oxydig Dräger, Lübeck) in the EC 145 helicopter two oxygen transport and application systems were compared. The new liquid oxygen system (LOX) for the oxygen therapy was assessed in an application observation. For physical reasons fluid oxygen evaporates during the stand-by phase and an increased concentration (22.8% O2) in the exhaust valve of LOX arises. On the other hand a high oxygen concentration (22.7% O2) was measured in the operation mode of the conventional pressure flask gas system (GAS). No increased concentration could be measured within the helicopter cabin (HEMS, PAX) comparing both oxygen systems. For transport and application of oxygen with a very big reserve for the air dependent intensive transport the results show that LOX is a sure low pressure system (3.4 bar).  相似文献   
996.
997.
OBJECTIVE: The objective of this study was to determine if temporomandibular joint (TMJ) samples positive for Chlamydia trachomatis have a greater presence of tumor necrosis factor-alpha (TNFalpha) or interleukin-6 (IL-6) when compared with Chlamydia-negative samples. STUDY DESIGN: Posterior bilaminar tissue samples removed during TMJ surgery from 70 patients were evaluated. Cryosections were stained using monoclonal antibody that identifies C. trachomatis. The presence of IL-6 and TNFalpha were evaluated by immunostaining in 15 samples positive and in 25 samples negative for the presence of C. trachomatis. RESULTS: Of the 70 TMJ samples, 32 (46%) were positive for C. trachomatis. In 15 samples positive for C. trachomatis, 10 (67%) were positive for TNFalpha and 7 (47%) for IL-6. In 25 samples negative for C. trachomatis, only 4 (16%) were positive for TNFalpha and only 2 (8%) for IL-6. Differences in C. trachomatis-positive samples versus negative were significant for both TNFalpha (P < .002) and IL-6 (P < .008). CONCLUSION: The presence of C. trachomatis in the TMJ is associated with a significantly increased presence of TNFalpha and IL-6.  相似文献   
998.
Isolated fractures of the metacarpal and phalangeal bones are common injuries of the upper extremities. They usually occur at the age of 10–40, whereas the highest incidence is observed in childhood. The results of treatment have an important impact for the practical value of the hand. This article aims to give a brief overview of the different fracture types and their treatment options.  相似文献   
999.
Haemoglobin (Hb) abnormalities in chronic obstructive pulmonary disease (COPD) are not well characterised. The present authors investigated the prevalence and association of abnormal Hb with clinical outcomes. Analysis of a prospective cohort of stable COPD outpatients (n = 683) in a USA Veterans Administration pulmonary clinic was undertaken. Patients were classified as anaemic (Hb <13 g.dL(-1)), polycythemic (Hb > or =17 g.dL(-1) and > or =15 g.dL(-1) for males and females, respectively) or normal. Demographic characteristics and physiological/functional outcomes were compared between groups. Regression models adjusting for confounders examined the independent association of anaemia with clinical outcomes. Anaemia was present in 116 (17%) patients and polycythemia in 40 (6%). While the only values that differed between polycythemic and nonpolycythemic patients were mean body mass index and Hb, anaemic patients showed a significantly higher modified Medical Research Council dyspnoea scale score (2.8 versus 2.6), lower 6-min walk distance (265 versus 325 m) and shorter median survival (49 versus 74 months) than nonanaemic patients. In regression models, anaemia independently predicted dyspnoea and reduced exercise capacity. Anaemia in chronic obstructive pulmonary disease was an independent risk factor for reduced functional capacity. Polycythemia prevalence was low and had no association with worsened outcomes. Further work is required to evaluate the effect of anaemia correction on outcomes in chronic obstructive pulmonary disease.  相似文献   
1000.
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