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   18150篇
  免费   1318篇
  国内免费   23篇
耳鼻咽喉   168篇
儿科学   704篇
妇产科学   686篇
基础医学   2412篇
口腔科学   236篇
临床医学   2887篇
内科学   3047篇
皮肤病学   349篇
神经病学   1518篇
特种医学   288篇
外科学   1670篇
综合类   382篇
一般理论   19篇
预防医学   2334篇
眼科学   402篇
药学   1182篇
中国医学   21篇
肿瘤学   1186篇
  2023年   111篇
  2022年   185篇
  2021年   421篇
  2020年   316篇
  2019年   410篇
  2018年   435篇
  2017年   328篇
  2016年   379篇
  2015年   424篇
  2014年   576篇
  2013年   850篇
  2012年   1334篇
  2011年   1459篇
  2010年   776篇
  2009年   625篇
  2008年   1227篇
  2007年   1296篇
  2006年   1215篇
  2005年   1247篇
  2004年   1155篇
  2003年   1104篇
  2002年   912篇
  2001年   161篇
  2000年   144篇
  1999年   140篇
  1998年   188篇
  1997年   188篇
  1996年   128篇
  1995年   110篇
  1994年   106篇
  1993年   99篇
  1992年   90篇
  1991年   91篇
  1990年   80篇
  1989年   89篇
  1988年   69篇
  1987年   56篇
  1986年   79篇
  1985年   64篇
  1984年   79篇
  1983年   75篇
  1982年   71篇
  1981年   56篇
  1980年   59篇
  1979年   50篇
  1978年   47篇
  1977年   31篇
  1976年   26篇
  1974年   36篇
  1972年   30篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
Ixodes dammini Spielman, Clifford, Piesman & Corwin collected from a study site in southwestern Wisconsin were examined for Borrelia burgdorferi infection. Adult spirochete infection rates varied seasonally (38.1%, spring 1990; 60.3%, fall 1990; 41.2%, spring 1991) and were similar to or higher than rates reported in various studies from the northeastern United States. Statistical comparison of seasonal infection rates indicated a significant difference between the fall 1990 adult population and the subsequent overwintered population of the same cohort (spring 1991). Additionally, a significant decrease in the intensity of spirochete infection was observed in the overwintered adult sample.  相似文献   
55.
Synovial sarcoma demonstrates epithelial differentiation, either by light microscopy (biphasic synovial sarcoma) or by immunohistochemical/ultrastructural methods only (monophasic) and poorly differentiated synovial sarcoma. Although the glands of synovial sarcoma are known to have tight junction-like structures, far less is known about junction formation in the spindled component of synovial sarcomas. Additionally, it is unknown whether the tight junctions of synovial sarcoma are normally constituted. The tight junction is a multiprotein complex consisting of numerous proteins that include ZO-1, claudin-1 and occludin. A total of 35 cases of synovial sarcoma (13 biphasic, 14 monophasic and eight poorly differentiated) were immunostained for ZO-1, claudin-1 and occludin using commercially available antibodies, heat-induced epitope retrieval and standard avidin-biotin technique. When available, corresponding electron micrographs were reviewed. For five cases, the presence of either an SYT-SSX1 (three cases) or SYT-SSX2 (two cases) gene fusion was known. Positive cases showed particulate membrane staining. The glands of biphasic synovial sarcomas expressed ZO-1 (13/13), claudin-1 (12/13) and occludin (11/13) in a manner identical to normal glandular epithelia, at the apical portion of the lateral membrane. The spindle cells of biphasic synovial sarcomas showed abnormal circumferential membranous expression of ZO-1 (12/13), claudin-1 (6/13) and occludin (3/13). Monophasic synovial sarcomas expressed ZO-1 in a circumferential pattern (13/14) but less often claudin-1 (4/14) or occludin (3/14). Poorly differentiated synovial sarcomas expressed ZO-1 (8/8) and claudin-1 (6/8) but only rarely occludin (2/8). By electron microscopy, recognizable tight junctions were seen only in glands. No correlation was seen between histologic subtype or fusion type and expression of tight junction proteins. We conclude that the glands of biphasic synovial sarcomas show well-organized, true epithelial tight junctions. In contrast, the spindled cells of all synovial sarcomas show significant abnormalities in the expression and localization of tight junction proteins, suggesting partial and/or aberrant epithelial differentiation.  相似文献   
56.
Background:  Sample sizes in studies of childhood chronic fatigue remain small and there is a need to integrate research findings and establish common criteria.
Method:  This is a detailed report of 20 children with medically unexplained fatigue, referred to as Chronic Fatigue Syndrome (CFS). It includes an uncontrolled outcome study of treatment based on a pragmatic cognitive-behavioural model adapted for children at Great Ormond Street Hospital for Children.
Results:  The data revealed psychological distress at 30 times the prevalence found in the normal child population, with specific high-ranking symptoms, including headache, social withdrawal and decreased appetite. Onset tended to occur at 11 years of age with some earlier problems at school age, suggesting it might be possible to identify those most at risk. Follow-up demonstrated improvement in 87% of the sample (parental report), a significant increase in school attendance and a significant decrease in symptom severity. Factors associated with good outcome were short duration of fatigue (less than a year) and behaviours that tended to combat the cycle of avoidance, such as carefully planned home-tuition.
Conclusions:  Recording a comprehensive range of symptoms and factors facilitates comparisons within and between child studies. It is proposed that symptom severity is a particularly relevant measure for Chronic Fatigue Syndrome which is characterised by persisting symptoms.  相似文献   
57.
AIMS: To present an age-stratified approach to the diagnosis of obstructive lung disease based on asthma and COPD guidelines and epidemiology. METHODS: Asthma guidelines emphasize the role of the history and physical examination, with pulmonary function used primarily to confirm the diagnosis. COPD guidelines begin with symptoms and risk exposure, presenting spirometry as the primary diagnostic maneuver. Data from the National Health Interview Survey and the Third National Health and Nutrition Examination Survey illustrate relationships in prevalence of asthma and COPD in nationally representative samples. RESULTS: Asthma prevalence in adults declines with age from 5-10% at age 20-40 to 4-8% above age 60. COPD is uncommon in adults under age 40 but increases with age, surpassing asthma in older adults. CONCLUSIONS: These trends suggest that asthma screening is most useful in adults up to age 40, after which COPD screening and differential diagnosis are of comparable or greater utility.  相似文献   
58.
Necrotizing fasciitis (NF) is a potentially fatal infection of the skin and soft tissue. The early presentation may first appear as cellulitis. The skin stays intact in the early stages of NF; this leads to a deceptive benign appearance. The skin typically appears red, hot and exquisitely tender. Blisters may or may not be present. Severe local pain, which is out of proportion to the size and type of wound, is a hallmark sign seen in NF. Recognition of the signs and symptoms, as well as timely diagnosis and treatment of this condition is imperative. This is necessary in order to assist in preventing widespread tissue destruction, and enhance favorable patient outcomes. The purpose of this paper is to increase the knowledge and understanding of NF and to discuss the nurses' role in minimizing unfavorable outcomes.  相似文献   
59.
60.
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