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   695篇
  免费   39篇
  国内免费   1篇
耳鼻咽喉   6篇
儿科学   42篇
妇产科学   7篇
基础医学   52篇
口腔科学   15篇
临床医学   102篇
内科学   139篇
皮肤病学   10篇
神经病学   107篇
特种医学   76篇
外科学   62篇
综合类   11篇
预防医学   41篇
眼科学   6篇
药学   27篇
中国医学   1篇
肿瘤学   31篇
  2020年   8篇
  2016年   7篇
  2015年   8篇
  2014年   10篇
  2013年   15篇
  2012年   9篇
  2011年   20篇
  2010年   8篇
  2009年   8篇
  2008年   12篇
  2007年   12篇
  2006年   13篇
  2005年   14篇
  2004年   18篇
  2003年   11篇
  2002年   13篇
  2001年   18篇
  2000年   9篇
  1999年   8篇
  1998年   15篇
  1997年   16篇
  1996年   11篇
  1995年   14篇
  1994年   16篇
  1993年   13篇
  1992年   16篇
  1991年   28篇
  1990年   18篇
  1989年   13篇
  1988年   16篇
  1987年   15篇
  1986年   19篇
  1985年   28篇
  1984年   18篇
  1983年   9篇
  1982年   12篇
  1980年   9篇
  1979年   22篇
  1978年   14篇
  1977年   12篇
  1976年   10篇
  1975年   10篇
  1974年   12篇
  1973年   14篇
  1972年   14篇
  1971年   9篇
  1970年   20篇
  1968年   10篇
  1967年   10篇
  1966年   13篇
排序方式: 共有735条查询结果,搜索用时 15 毫秒
11.
Using age-specific rates for multiple sclerosis (MS) based on a national survey, the number of "naturally occurring" new cases of MS among the 45 million swine flu vaccine recipients in the United States is estimated as 1,624 during the year after vaccination, or 31 cases per week. Information from available reports and publications indicates no excess over the expected frequencies. Analyses of admissions for MS before, during, and after the immunization program showed no increase to the US Army hospitals or to the Mayo Clinic. Three independent controlled clinical investigations performed on patients with MS showed no increase in the frequency of exacerbations among those receiving swine flu vaccine as compared with those receiving placebo. Epidemiologic features of MS do not implicate killed virus vaccine as an etiologic factor in onset or exacerbations of the disease. There is no indication from these analyses of any association or cause-and-effect relationship between swine flu vaccine and MS.  相似文献   
12.
Inflamed fibronectin: an altered fibronectin enhances neutrophil adhesion   总被引:4,自引:0,他引:4  
Vercellotti  GM; McCarthy  J; Furcht  LT; Jacob  HS; Moldow  CF 《Blood》1983,62(5):1063-1069
Recent investigations have emphasized the role of activated granulocytes in mediating vascular endothelial injury in the pathogenesis of shock lung. In vitro studies have indicated that tight adherence of the neutrophil to the endothelium is crucial for the development of cellular injury. Fibronectin is critical to cell-to- substratum and cell-to-cell interactions. Since fibronectin resides in plasma, on endothelial cell surfaces and is secreted into cell matrices, the adhesive properties of fibronectin must be modulated, lest universal cell agglomeration occur, yet be enhanced when cell attachment is appropriate. In these studies, treatment of fibronectin- coated surfaces with neutrophil release products increased the adhesion of activated neutrophils. Similarly, endothelial cells treated with neutrophil release products become a more adherent substrate for neutrophils. This enhanced adherence generated by treatment of fibronectin with neutrophil supernatants is inhibitable by heat and the lysosomal proteinase inhibitor, pepstatin-A. Neutrophil release products cause proteolytic fragmentation of fibronectin and enhanced fibronectin immunofluorescence on endothelial cells. In addition, neutrophils are more injurious to endothelial cells that have been pretreated with neutrophil release products. Neutrophils may enhance their own adherence to endothelial cells by altering fibronectin, and this altered, or "inflamed," fibronectin may serve as an amplifier of inflammation.  相似文献   
13.
Children with cystic fibrosis have variable degrees of exocrine pancreatic insufficiency which, if untreated, is the main cause of fat malabsorption. The impact of pancreatic enzyme supplementation on fat digestion was measured in 41 children with cystic fibrosis, 11 healthy controls, and five children with mucosal diseases by a non-invasive test of intraluminal lipolysis using 13carbon (13C) labelled mixed triglyceride (1,3-distearyl, 2[13C] octanoyl glycerol). The children with cystic fibrosis without pancreatic supplements had a median (range) 13C cumulative percentage dose recovered over six hours (cPDR) of 3.1% (0-31.7), the controls 31.0% (21.8-41.1), and the subjects with mucosal disease 27.8% (19.7-32.5). In 23 subjects with cystic fibrosis the usual dose of pancreatic enzyme supplements increased the cPDR to a median of 23.9% (0-45.6), and twice the usual dose of enteric coated microspheres increased the cPDR to 31.1% (11.1-47.8). There was no significant difference between the median cPDR of normal controls and children with mucosal disease, but there was a highly significant difference between these groups and children with untreated cystic fibrosis. Thirteen children with cystic fibrosis had no 13C recovery in their breath without enzymes and 10 showed marked increases with regular enzymes. In eight children doubling the dose of enzymes caused no or minimal improvement. The mixed triglyceride breath test offers a simple, non-invasive way of assessing the need for pancreatic enzyme supplementation in children with cystic fibrosis and could be used to optimise treatment.  相似文献   
14.
BACKGROUND: To evaluate the efficacy and toxicity of cisplatin/etoposide continuous infusion chemotherapy for cancer of unknown primary site in Taiwan, a region with a high prevalence of endemic viral infections. METHOD: Between April 1994 and February 1996, 20 patients with a diagnosis of CUPS were treated, including 15 males and five females, of average age 63.3 years (range 41-83 years). Continuous intravenous infusion of etoposide 80 mg/m2 and cisplatin 25 mg/m2 was given for 3 days every 3 weeks. Pretreatment tumor marker and viral serology studies were performed for baseline evaluation. Nearly two-thirds of the patients had poorly differentiated carcinoma. The average number of metastatic sites was 2.65 (range 1-4), with liver and lymph node involvement predominating. RESULTS: The overall response rate was 25% (95% CI 17.7-32.3%); 30.7% for poorly differentiated cancers and 25% for well differentiated cancers. Median survival was 4 months (range 1-12 months), 4.8 months for patients attaining partial response. Toxicity was moderate, grade 3 and 4 neutropenia occurred in 55% and grade 3 and 4 thrombocytopenia in 40%; other toxicities were mild. CA125 and CA199 were elevated in more than 50% of patients. Viral serology studies were not significantly different from those of the indigenous population. CONCLUSION: Etoposide and cisplatin combination chemotherapy has modest activity in patients with extensive CUPS and, at the schedule and dosage given, it is associated with moderate toxicity.   相似文献   
15.
No reports of the incidence rates for primary systemic amyloidosis (AL) have come to our attention. Records of all residents of Olmstead County, Minnesota, with a diagnosis of amyloidosis were obtained from the Mayo Clinic and its affiliated hospitals, as well as other medical groups that might have seen local patients for the period January 1, 1950 to December 31, 1989. Twenty-one patients fulfilled the criteria for the diagnosis of AL. The median age was 73.5 years, and 62% were men. In all but one patient the diagnosis was made ante mortem. The clinical data of the 21 patients were similar to those referral patients with AL seen at Mayo Clinic. Immunohistochemical stains were positive for monoclonal light chains in the amyloid deposits in 15 of the 21 cases. In six cases, tissue was not available for immunohistochemical studies. Three of the six patients without immunohistochemical stains had a free monoclonal lambda light chain in the urine, and the other three had a monoclonal serum protein. Immunoelectrophoresis/immunofixation detected a monoclonal (M)-protein in the serum of 16 of 17 patients tested. A monoclonal light chain was found in the urine of 10 of 15 patients. The overall sex- and age-adjusted rate per million person-years was 6.1 from 1950 to 1969 and 10.5 from 1970 to 1989. The similarity of these rates suggests no significant increase over time.  相似文献   
16.
OBJECTIVE. To explore alterations in energy utilization as a potential etiology for weakness in polymyositis and dermatomyositis (PM/DM). METHODS. P-31 magnetic resonance spectroscopy studies were performed in patients with acute and treated PM/DM and in normal controls, at rest and with exercise. RESULTS. Patients with acute and treated PM/DM showed increased ratios of inorganic phosphate to phosphocreatine (PCr) during exercise, with loss of ATP disproportional to loss of PCr. CONCLUSION. This study demonstrates changes in energy utilization in PM/DM, thus supporting the notion of a metabolic etiology for the weakness associated with these diseases.  相似文献   
17.
18.
T-cell subsets were determined by the Leu monoclonal antibodies in the peripheral blood and/or bone marrow of 52 patients with B-cell chronic lymphocytic leukemia (B-CLL) not on therapy at the time of study. The diagnosis of B-CLL required that the leukemic cells expressed surface receptors for "la-like" antigen, Fc fragment of IgG, mouse red blood cells (MRBC), C3-coated red cells (EAC), and low density of monoclonal surface immunoglobulin. The Leu-3a+/2a+ ratio was applied to define the balance between the helper/suppressor subsets in the residual T-lymphocytes. Most patients showed a decrease in the Leu-3a+/2a+ ratios at all stages of disease. The decrease in ratio was mainly related to a decrease in the Leu-3a+ T-cell subset. The more advanced stages of B-CLL were associated with lower Leu-3a+/2a+ ratio, higher total white cell and percent lymphocyte counts. There was no correlation between the proportion of EAC or MRBC rosetting cells and stages of B-CLL. This analysis further suggests that B-CLL is an immunosuppressed state that becomes more pronounced in the advanced stages and is characterized by a progressive decrease in the Leu-3a+ (helper) T-cell subset.  相似文献   
19.
20.
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