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   2025891篇
  免费   151246篇
  国内免费   4417篇
耳鼻咽喉   26730篇
儿科学   66663篇
妇产科学   55773篇
基础医学   296347篇
口腔科学   56322篇
临床医学   181716篇
内科学   399173篇
皮肤病学   47426篇
神经病学   159100篇
特种医学   75364篇
外国民族医学   531篇
外科学   300536篇
综合类   44996篇
现状与发展   5篇
一般理论   641篇
预防医学   157170篇
眼科学   46318篇
药学   146033篇
  3篇
中国医学   5498篇
肿瘤学   115209篇
  2021年   16329篇
  2019年   17112篇
  2018年   24542篇
  2017年   18387篇
  2016年   20523篇
  2015年   22791篇
  2014年   31678篇
  2013年   47258篇
  2012年   64551篇
  2011年   68695篇
  2010年   40026篇
  2009年   37499篇
  2008年   62875篇
  2007年   66779篇
  2006年   67407篇
  2005年   64698篇
  2004年   62235篇
  2003年   59165篇
  2002年   57142篇
  2001年   100982篇
  2000年   103357篇
  1999年   85210篇
  1998年   23441篇
  1997年   20768篇
  1996年   20983篇
  1995年   19936篇
  1994年   18123篇
  1993年   16952篇
  1992年   64206篇
  1991年   61989篇
  1990年   59816篇
  1989年   57653篇
  1988年   52667篇
  1987年   51392篇
  1986年   48300篇
  1985年   45797篇
  1984年   34463篇
  1983年   29048篇
  1982年   17178篇
  1979年   30573篇
  1978年   21511篇
  1977年   18006篇
  1976年   17138篇
  1975年   18119篇
  1974年   21514篇
  1973年   20710篇
  1972年   19416篇
  1971年   17787篇
  1970年   17003篇
  1969年   15652篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
We report two British cases of liver abscess, due to Klebsiella pneumoniae and associated with synchronous infection elsewhere, which required liver resection for definitive treatment. They illustrate the geographic spread of aggressive K pneumoniae liver infection and demonstrate the importance of early aggressive treatment.  相似文献   
3.
4.
5.
Sinus venosus atrial septal defect (SV‐ASD) usually coexists with partial anomalous pulmonary vein connection (PAPVC). It is a difficult diagnosis in transthoracic echocardiography (TTE) due to eccentric position of defects. We present a rare case of atypical anatomical variation in PAPVC, which was never described before. Two right pulmonary veins drained into superior vena cava, which overrode SV‐ASD and interatrial septum, a third pulmonary vein into the right atrium. Complete diagnosis could not be set after TTE, nor transesophageal echocardiography, whereas angio‐CT was finally conclusive. This diagnostic approach allowed the surgical planning.  相似文献   
6.
7.
8.
Analyzing functional species’ characteristics (species traits) that represent physiological, life history and morphological characteristics of species help understanding the impacts of various stressors on aquatic communities at field conditions. This research aimed to study the combined effects of pesticides and other environmental factors (temperature, dissolved oxygen, dissolved organic carbon, floating macrophytes cover, phosphate, nitrite, and nitrate) on the trait modality distribution of aquatic macrofauna communities. To this purpose, a field inventory was performed in a flower bulb growing area of the Netherlands with significant variation in pesticides pressures. Macrofauna community composition, water chemistry parameters and pesticide concentrations in ditches next to flower bulb fields were determined. Trait modalities of nine traits (feeding mode, respiration mode, locomotion type, resistance form, reproduction mode, life stage, voltinism, saprobity, maximum body size) likely to indicate pesticides impacts were analyzed. According to a redundancy analysis, phosphate -and not pesticides- constituted the main factor structuring the trait modality distribution of aquatic macrofauna. The functional composition could be ascribed for 2–4 % to pesticides, and for 3–11 % to phosphate. The lack of trait responses to pesticides may indicate that species may have used alternative strategies to adapt to ambient pesticides stress. Biomass of animals exhibiting trait modalities related to feeding by predation and grazing, presence of diapause form or dormancy, reproduction by free clutches and ovoviviparity, life stage of larvae and pupa, was negatively correlated to the concentration of phosphate. Hence, despite the high pesticide pollution in the area, variation in nutrient-related stressors seems to be the dominant driver of the functional composition of aquatic macrofauna assembly in agricultural ditches.  相似文献   
9.
10.
Haemophilia is a common cause of genetically inherited bleeding disorders. Pseudotumours occur in 1–2 % of persons with severe forms of haemophilia. These are a result of repeated haemorrhage into soft tissues, subperiosteum or a site of bone fracture with inadequate resorption of the extravasated blood. There are a number of therapeutic alternatives for this dangerous condition: surgical removal, percutaneous management, irradiation, embolization etc. In this case report, we describe the natural history, clinical course and successful surgical management of a patient with haemophilia who presented with a massive pseudotumour. We also briefly review the relevant literature on the various therapeutic modalities that have been implemented in the management of this rare complication. Though surgeons may be averse to operate on haemophiliacs, primary surgical management as done in our case may prove to be the definitive treatment option for such patients.  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