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   4698篇
  免费   295篇
  国内免费   23篇
耳鼻咽喉   48篇
儿科学   142篇
妇产科学   123篇
基础医学   609篇
口腔科学   108篇
临床医学   440篇
内科学   1029篇
皮肤病学   80篇
神经病学   418篇
特种医学   199篇
外科学   598篇
综合类   24篇
一般理论   1篇
预防医学   396篇
眼科学   73篇
药学   340篇
中国医学   12篇
肿瘤学   376篇
  2024年   7篇
  2023年   39篇
  2022年   74篇
  2021年   143篇
  2020年   111篇
  2019年   137篇
  2018年   132篇
  2017年   99篇
  2016年   113篇
  2015年   134篇
  2014年   180篇
  2013年   244篇
  2012年   392篇
  2011年   430篇
  2010年   201篇
  2009年   172篇
  2008年   306篇
  2007年   333篇
  2006年   281篇
  2005年   294篇
  2004年   251篇
  2003年   219篇
  2002年   175篇
  2001年   58篇
  2000年   55篇
  1999年   48篇
  1998年   31篇
  1997年   33篇
  1996年   17篇
  1995年   24篇
  1994年   29篇
  1993年   16篇
  1992年   21篇
  1991年   19篇
  1990年   16篇
  1989年   21篇
  1988年   17篇
  1987年   14篇
  1986年   13篇
  1985年   23篇
  1984年   20篇
  1983年   17篇
  1982年   9篇
  1981年   5篇
  1979年   6篇
  1978年   6篇
  1974年   3篇
  1971年   4篇
  1969年   7篇
  1968年   4篇
排序方式: 共有5016条查询结果,搜索用时 31 毫秒
41.
We describe patient E.P. who occasionally perceives a ‘ghost' hand which copies the previous positions of the left hand with a 0.5–1 min time lag, but follows the movement patterns of the right hand. The symptoms started after an operation of a ruptured aneurysm, followed by an infarction of the right frontal lobe; E.P. also has a previously lesioned corpus callosum. Neuromagnetic recordings revealed that activity of the left secondary somatosensory cortex was strongly suppressed during the ghost arm percept, thereby providing an objective correlate for E.P.'s sensations. We conclude that simultaneous mental contents about body scheme may be based on neural information extracted at considerably different times, resulting in fragmentation of bodily awareness.  相似文献   
42.
Enrichment of dendritic cells from human peripheral blood   总被引:3,自引:0,他引:3  
A simplified method is described for purification of dendritic cells from human peripheral blood. The method is based on depletion of phagocytes with carbonyl iron and magnet, followed by centrifugation of nonphagocytic cells on Percoll and elimination of contaminating T lymphocytes, B lymphocytes, natural killer cells, and monocytes from the low-density cell fraction by treatment with monoclonal antibodies and complement. The purity of enriched dendritic cells was about 80% and these cells represented 0.2% of the starting mononuclear cell population. Dendritic cells were potent autologous and allogeneic stimulators in mixed leukocyte cultures.  相似文献   
43.
44.
OBJECTIVE: Although an association between stressful life events and health problems has been demonstrated, the underlying mechanisms have remained unclear. We examined whether psychological problems and health-risk behaviors underpin the health effects of different event categories. METHOD: The initially healthy participants were 2991 (796 men, 2195 women) municipal employees who had taken no sick leave in 1995. In 1997, they completed a questionnaire requesting information on recent life events and psychological and behavioral factors. The outcome was recorded sickness absences in 1998. RESULTS: In men, the death or serious illness of a family member, violence, and financial difficulties increased the risk of later sickness absence. According to structural equation modeling, violence and financial difficulties also induced psychological problems such as anxiety, mental distress, and lowered sense of coherence. Psychological problems were associated with heightened cigarette and alcohol consumption, which in turn increased sickness absence. A corresponding structural model did not fit the data in relation to death or serious illness of a family member. In women, life events were associated with psychological problems and smoking but not sickness absence. CONCLUSIONS: Longitudinal evidence suggests that increased psychological problems and behaviors involving risk to health partially mediate the effect of stressful life events on health, as indicated by sickness absence. This model received support among men and for the event categories of violence and financial difficulties. Women were less affected by stressful life events than men.  相似文献   
45.
Binding of human and rat CD59 to the terminal complement complexes.   总被引:1,自引:1,他引:1       下载免费PDF全文
T Lehto  B P Morgan    S Meri 《Immunology》1997,90(1):121-128
CD59-antigen (protectin) is a widely distributed glycolipid-anchored inhibitor of complement lysis. CD59 interacts with complement components C8 and C9 during assembly of the membrane attack complex (MAC). To evaluate species specificity of these interactions we have in the present study examined cross-species binding of isolated human and rat CD59 to the terminal complement components C8 and C9. By using primarily soluble CD59 isolated from urine (CD59U) potentially non-specific binding interactions of the phospholipid portion of the membrane forms of CD59 could be avoided. Sucrose density gradient ultracentrifugation analysis showed that human CD59U bound to both human and rat C8 in the SC5b-8 complexes. Similar binding occurred when rat CD59U was used. The degree of binding did not significantly differ between the heterologous and homologous CD59-C8 combinations. C9 from both species inhibited the binding of CD59 to soluble SC5b-8. In ligand blotting analysis human and rat CD59U bound to human and rat C8 alpha gamma-subunit and C9. Binding of human and rat CD59U was stronger to human than rat C9. In plate binding assays the erythrocyte form of CD59 (CD59E) bound to both human and rat C8. Binding of CD59E to heterologous C9 was considerably weaker than to homologous C9. Our results imply that the reciprocal binding sites between C8 and CD59 and to a lesser degree between CD59 and C9 are conserved between human and rat. Interactions of CD59 with the terminal C components are thus species selective but not 'homologously restricted'.  相似文献   
46.
Some skin and soft tumors, which generally are assumed to be derived from endothelial cells or blood vessels, were characterized with fluorochrome-labeled Ulex europaeus I agglutinin (UEA I), recently shown to bind specifically to endothelial cells in various normal human tissues. The staining pattern was compared with that obtained with immunostaining using antibodies against factor-VIII-related antigen (FVIII-RAG), a known marker for endothelial cells. The results showed that UEA-I is a specific and a more sensitive marker for the endothelial cells in benign vascular lesions as compared with anti-FVIII-RAG. UEA-I also stained many neoplastic cells of endothelial sarcomas, which generally were negative for FVIII-RAG. Melanomas, anaplastic carcinomas, and other types of sarcomas were negative for both UEA-I and FVIII-RAG. The results suggest that UEA-I lectin is a specific and sensitive adjunct tool in demonstrating endothelial cells and endothelial derivation of human tumors.  相似文献   
47.
Basophil histamine release and lymphocyte proliferation tests were examined with latex allergen prepared from surgical gloves in 15 patients with latex contact urticaria. The basophil histamine release test (BHRT) yielded positive results in 13/14 (93%) patients, whereas commercial latex RAST was positive in only 9/15 (60%) patients. Lymphocyte proliferation test (LPT) was positive in 3/15 (20%) patients, suggesting that cell-mediated immune reactions may also occur in latex allergy. However, patch tests to latex were negative and neither were epidermal Langerhans cells able to present latex antigen to T lymphocytes in vitro.  相似文献   
48.
49.
The presence of a significant organ dysfunction does not immediately exclude patients from consideration for treatment with a left ventricular assist system (LVAS). However, in treating morbid circulatory shock patients with multiple organ failure, it is important to know the preoperative and postoperative factor or factors related to the recovery of the damaged organ function. In this study, we retrospectively analyzed patients receiving a LVAS at our institution and tried to determine the important factors related to the survival of patients with multisystem failure. Twenty-seven patients who underwent LVAS placement at Saitama Medical School Hospital between 1993 and 2003 were included in this study. The preoperative risk factors analyzed were renal dysfunction, respiratory dysfunction, hepatic dysfunction, the existence of active infection, and the combination of all four factors. As a postoperative factor, the pump flow index (mean LVAS pump flow during the first 2 weeks after LVAS surgery divided by the body surface area) was analyzed. None of the analyzed preoperative factors could predict survival after LVAS surgery, but a pump flow index of less than 2.5 l/min/m2 had a significant relationship with death after LVAS surgery. Further analysis revealed that all the patients with a pump flow index of 3.0 l/min/m2 or more could overcome preoperative organ dysfunction. Congestive heart failure patients with multisystem failure need luxury pump flow for successful LVAS surgery; this factor could be especially important in device selection and postoperative management.  相似文献   
50.
Malnutrition negatively affects the quality of life of patients with dysphagia. Despite the need for nutritional status assessment in patients with dysphagia, standard, effective nutritional assessments are not yet available, and the identification of optimal nutritional assessment items for patients with dysphagia is inadequate. We conducted a scoping review of the use of nutritional assessment items in adult patients with oropharyngeal and esophageal dysphagia. The MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials databases were searched to identify articles published in English within the last 30 years. Twenty-two studies met the inclusion criteria. Seven nutritional assessment categories were identified: body mass index (BMI), nutritional screening tool, anthropometric measurements, body composition, dietary assessment, blood biomarkers, and other. BMI and albumin were more commonly assessed in adults. The Global Leadership Initiative on Malnutrition (GLIM), defining new diagnostic criteria for malnutrition, includes the categories of BMI, nutritional screening tool, anthropometric measurements, body composition, and dietary assessment as its required components, but not the blood biomarkers and the “other” categories. We recommend assessing nutritional status, including GLIM criteria, in adult patients with dysphagia. This would standardize nutritional assessments in patients with dysphagia and allow future global comparisons of the prevalence and outcomes of malnutrition, as well as of appropriate interventions.  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