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   3115篇
  免费   319篇
  国内免费   23篇
耳鼻咽喉   25篇
儿科学   134篇
妇产科学   56篇
基础医学   346篇
口腔科学   72篇
临床医学   373篇
内科学   548篇
皮肤病学   130篇
神经病学   142篇
特种医学   169篇
外科学   426篇
综合类   272篇
现状与发展   30篇
一般理论   1篇
预防医学   330篇
眼科学   48篇
药学   182篇
中国医学   21篇
肿瘤学   152篇
  2024年   14篇
  2023年   195篇
  2022年   62篇
  2021年   103篇
  2020年   114篇
  2019年   61篇
  2018年   106篇
  2017年   85篇
  2016年   87篇
  2015年   105篇
  2014年   138篇
  2013年   155篇
  2012年   187篇
  2011年   169篇
  2010年   168篇
  2009年   152篇
  2008年   127篇
  2007年   147篇
  2006年   110篇
  2005年   100篇
  2004年   96篇
  2003年   112篇
  2002年   80篇
  2001年   64篇
  2000年   73篇
  1999年   77篇
  1998年   56篇
  1997年   59篇
  1996年   56篇
  1995年   39篇
  1994年   39篇
  1993年   34篇
  1992年   16篇
  1991年   19篇
  1990年   14篇
  1989年   36篇
  1988年   30篇
  1987年   20篇
  1986年   13篇
  1985年   15篇
  1984年   12篇
  1983年   7篇
  1982年   9篇
  1981年   11篇
  1980年   13篇
  1978年   5篇
  1977年   5篇
  1976年   16篇
  1975年   14篇
  1974年   5篇
排序方式: 共有3457条查询结果,搜索用时 15 毫秒
1.
Coronavirus disease-19 (COVID-19) caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is now a pandemic threat. This virus is supposed to be spread by human to human transmission. Cellular angiotensin-converting enzyme 2 (ACE2) is the receptor of SARS-CoV-2 which is identical or similar in different species of animals such as pigs, ferrets, cats, orangutans, monkeys, and humans. Moreover, a recent study predicted that dogs might be secondary hosts during the evolution of SARS-CoV-2 from bat to human. Therefore, there is a possibility of spreading SARS-CoV-2 through domestic pets. There are now many reports of SARS-CoV-2 positive cases in dogs, cats, tigers, lion, and minks. Experimental data showed ferrets and cats are highly susceptible to SARS-CoV-2 as infected by virus inoculation and can transmit the virus directly or indirectly by droplets or airborne routes. Based on these natural infection reports and experimental data, whether the pets are responsible for SARS-CoV-2 spread to humans; needs to be deeply investigated. Humans showing clinical symptoms of respiratory infections have been undergoing for the COVID-19 diagnostic test but many infected people and few pets confirmed with SARS-CoV-2 remained asymptomatic. In this review, we summarize the natural cases of SARS-CoV-2 in animals with the latest researches conducted in this field. This review will be helpful to think insights of SARS-CoV-2 transmissions, spread, and demand for seroprevalence studies, especially in companion animals.  相似文献   
2.
3.
4.
Hysterosalpingography was performed in 31 patients by means of a low-dose scanning-beam digital radiographic system. The technique permits adequate evaluation of gynecologic abnormalities while allowing significant reduction in radiation: 2.4-mR (6.1 X 10(-7) C/kg) exposure to the skin and 0.7-mrad (7 X 10(-6) Gy) mean dose to the ovaries per image obtained. Sixteen patients demonstrated readily recognizable and documented abnormalities, corroborated by laparoscopy, laparotomy, or other supportive evidence.  相似文献   
5.
6.
OBJECTIVES: Deep hypothermic circulatory arrest (DHCA) is commonly used during thoracic aortic surgery, and is initiated only after a sufficient degree of cerebral hypothermia is induced. The criteria for initiating DHCA vary among institutions: most centers use temperature criteria, some use electroencephalography, and a minority use jugular bulb oxyhemoglobin saturation SjO(2) criteria. The purpose of this study was to determine whether the use of SjO(2) monitoring to guide the onset of DHCA was associated with better post-operative neuropsychological outcome. METHODS: Sixty-one thoracic aortic surgical patients underwent both pre- and post-operative neuropsychological testing. Patients were divided into three groups: (1) those with SjO(2)> or =95% at DHCA onset; (2) those with SjO(2)<95% at DHCA onset; and (3) those without SjO(2) monitoring. RESULTS: There were no statistically significant differences in the incidence of post-operative decline in neuropsychological function among the three groups of patients. Patients in whom SjO(2) data were used to guide onset of DHCA had lower esophageal and bladder temperatures at that time compared with patients without SjO(2) monitoring. CONCLUSIONS: Monitoring of SjO(2) had no apparent effect upon post-operative neuropsychological outcome, and there were no trends in our small patient cohort suggesting differences that our study was not adequately powered to detect. Use of SjO(2) monitoring was associated with more profound hypothermia prior to DHCA due to more prolonged cooling in attempts to bring the SjO(2) above the 95% threshold. Using our institutional cooling protocol, SjO(2) monitoring does not appear to increase neuroprotection in patients undergoing DHCA for thoracic aortic repairs.  相似文献   
7.
Defecography in multiple sclerosis patients with severe constipation   总被引:3,自引:0,他引:3  
Gill  KP; Chia  YW; Henry  MM; Shorvon  PJ 《Radiology》1994,191(2):553
  相似文献   
8.
9.
10.
Solitary bronchioloalveolar carcinoma: CT criteria   总被引:14,自引:0,他引:14  
The computed tomographic (CT) scans of 30 patients with solitary bronchioloalveolar carcinoma were reviewed. Common features at CT included the peripheral or subpleural location of a pulmonary mass (25 cases), pseudocavitation (18 cases), heterogeneous attenuation (17 cases), irregular margins forming a star pattern (22 cases), and pleural tags (21 cases). Using these CT criteria, four independent observers attempted to identify cases of bronchioloalveolar carcinoma from a larger sample of lung cancers and benign lesions by categorizing a series of test cases into four probability categories. Although the bronchioloalveolar carcinomas were correctly ranked in the two highest probability categories 75% of the time (in 45 of 60 cases), there was considerable overlap with other lung lesions, particularly with adenocarcinoma and large cell undifferentiated carcinoma. However, even though the typical features of bronchioloalveolar carcinoma are not invariable or highly specific, they are characteristic enough to suggest the diagnosis.  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