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   696篇
  免费   42篇
  国内免费   7篇
耳鼻咽喉   22篇
儿科学   38篇
妇产科学   2篇
基础医学   63篇
口腔科学   40篇
临床医学   46篇
内科学   193篇
皮肤病学   13篇
神经病学   12篇
特种医学   81篇
外科学   79篇
综合类   62篇
预防医学   27篇
眼科学   8篇
药学   21篇
肿瘤学   38篇
  2023年   3篇
  2022年   7篇
  2021年   10篇
  2020年   8篇
  2019年   11篇
  2018年   10篇
  2017年   4篇
  2016年   11篇
  2015年   19篇
  2014年   24篇
  2013年   21篇
  2012年   16篇
  2011年   15篇
  2010年   34篇
  2009年   39篇
  2008年   18篇
  2007年   34篇
  2006年   38篇
  2005年   17篇
  2004年   14篇
  2003年   10篇
  2002年   12篇
  2001年   13篇
  2000年   10篇
  1999年   17篇
  1998年   42篇
  1997年   32篇
  1996年   40篇
  1995年   18篇
  1994年   19篇
  1993年   22篇
  1992年   4篇
  1991年   9篇
  1990年   5篇
  1989年   10篇
  1988年   24篇
  1987年   11篇
  1986年   11篇
  1985年   19篇
  1984年   7篇
  1983年   6篇
  1982年   3篇
  1981年   3篇
  1980年   4篇
  1979年   5篇
  1978年   3篇
  1977年   4篇
  1976年   7篇
  1975年   5篇
  1966年   3篇
排序方式: 共有745条查询结果,搜索用时 15 毫秒
81.
Fifteen allograft transplant recipients acquired lymphoproliferative disorders after immunosuppressive therapy with cyclosporine and steroids. Many of these lymphoproliferative disorders regressed or disappeared completely after reduction of cyclosporine dose. This disease has several aspects that distinguish it from usual posttransplantation lymphomas that occur with regimens that do not contain cyclosporine. The time course from transplantation to onset of lymphoma is relatively short, with an average of approximately 8 months. Organs show a wide spectrum of abnormalities typical of other immunosuppression-associated lymphomas, but there is unique sparing of the central nervous system. The tumor is also unique in that it responds to a decrease in the cyclosporine dose.  相似文献   
82.
Background Conflicting evidence suggests a possible role for vitamin E in mammalian glucose metabolism and the protection from type 2 diabetes. The alpha-tocopherol transfer protein (α-TTP) mediates the transfer of α-tocopherol (α-TOH) from hepatocytes to very-low-density lipoproteins, thereby controlling plasma levels of α-TOH. Aim of the study The aim of this study was to investigate the putative impact of α-TTP knock-out on glucose metabolism in mice. Methods Mice deficient for α-TTP and wild-type control littermates were fed a diet containing 200 mg α-tocopheryl acetate per kg to ameliorate α-TOH deficiency in knock-out mice. We investigated fasting and postprandial plasma glucose, insulin and triglyceride levels of both groups of mice at different ages. All genotypes and age groups were further subjected to glucose and insulin tolerance tests, and number of insulin-producing islets of Langerhans were determined. Results Plasma α-TOH levels of knock-out mice were 34% the levels of wild-type controls: Any signs of α-TOH deficiency were absent at any age. Unexpectedly, serum glucose levels both in the fasted and in the fed state were lower in α-TTP-deficient mice at any age. Removal rates for intraperitoneally injected glucose were found to be significantly increased in young α-TTP-deficient mice. This improved glucose tolerance was caused by increased insulin secretion in response to an intraperitoneal glucose challenge due to an increased number of pancreatic islets, as well as by increased sensitivity to intraperitoneally injected insulin, both significantly promoting glucose metabolism in α-TTP-deficient mice. Conclusions Our findings suggest that α-TTP-deficiency in states of α-TOH supplementation unexpectedly promotes glucose tolerance in mice due to both increased insulin secretion and insulin action, suggesting differential roles of α-TTP and α-TOH in the pathogenesis of type 2 diabetes mellitus. Marc Birringer and Doreen Kuhlow have contributed equally to this publication.  相似文献   
83.
Activation of peroxisome proliferator-activated receptor gamma (PPARgamma) by thiazolidinediones (TZDs) improves insulin resistance by increasing insulin-stimulated glucose disposal in skeletal muscle. It remains debatable whether the effect of TZDs on muscle is direct or indirect via adipose tissue. We therefore generated mice with muscle-specific PPARgamma knockout (MuPPARgammaKO) using Cre/loxP recombination. Interestingly, MuPPARgammaKO mice developed excess adiposity despite reduced dietary intake. Although insulin-stimulated glucose uptake in muscle was not impaired, MuPPARgammaKO mice had whole-body insulin resistance with a 36% reduction (P < 0.05) in the glucose infusion rate required to maintain euglycemia during hyperinsulinemic clamp, primarily due to dramatic impairment in hepatic insulin action. When placed on a high-fat diet, MuPPARgammaKO mice developed hyperinsulinemia and impaired glucose homeostasis identical to controls. Simultaneous treatment with TZD ameliorated these high fat-induced defects in MuPPARgammaKO mice to a degree identical to controls. There was also altered expression of several lipid metabolism genes in the muscle of MuPPARgammaKO mice. Thus, muscle PPARgamma is not required for the antidiabetic effects of TZDs, but has a hitherto unsuspected role for maintenance of normal adiposity, whole-body insulin sensitivity, and hepatic insulin action. The tissue crosstalk mediating these effects is perhaps due to altered lipid metabolism in muscle.  相似文献   
84.
Human longevity continues to increase world-wide, often accompanied by decreasing birth rates. As a larger fraction of the population thus gets older, the number of people suffering from disease or disability increases dramatically, presenting a major societal challenge. Healthy ageing has therefore been selected by EU policy makers as an important priority (http://www.healthyageing.eu/european-policies-and-initiatives); it benefits not only the elderly but also their direct environment and broader society, as well as the economy. The theme of healthy ageing figures prominently in the Horizon 2020 programme (https://ec.europa.eu/programmes/horizon2020/en/h2020-section/health-demographic-change-and-wellbeing), which has launched several research and innovation actions (RIA), like “Understanding health, ageing and disease: determinants, risk factors and pathways” in the work programme on “Personalising healthcare” (https://ec.europa.eu/research/participants/portal/desktop/en/opportunities/h2020/topics/693-phc-01-2014.html). Here we present our research proposal entitled “ageing with elegans” (AwE) (http://www.h2020awe.eu/), funded by this RIA, which aims for better understanding of the factors causing health and disease in ageing, and to develop evidence-based prevention, diagnostic, therapeutic and other strategies. The aim of this article, authored by the principal investigators of the 17 collaborating teams, is to describe briefly the rationale, aims, strategies and work packages of AwE for the purposes of sharing our ideas and plans with the biogerontological community in order to invite scientific feedback, suggestions, and criticism.  相似文献   
85.
The present study in patients with aplastic anemia was undertaken to determine whether exposure of recipients to donor blood products 24 hr before preparation with cyclophosphamide (1) enhanced the rate of sustained engraftment of marrow from HLA-identical siblings as suggested by animal experiments, (2) increased the rejection rate, in particular in transfused patients who may already have been exposed to donor antigens by blood products, or (3) was of no relevance to the outcome of transplantation of marrow from HLA-identical siblings. One- hundred fifty-five patients were studied, of whom 78 received blood products from the marrow donor 24 hr before cyclophosphamide and 77 did not. A binary logistic regression analysis was applied to the data, simultaneously considering five previously known risk factors for rejection. Results showed that preceding transfusion of donor blood products had neither a significant beneficial nor detrimental effect on the incidence of sustained engraftment.  相似文献   
86.
我非常高兴向大家推荐这份发展中国家幽门螺杆菌(H.priori)临床指南。该指南的编译是由数位在该领域具有丰富临床经验的世界知名专家共同完成的。  相似文献   
87.
88.

OBJECTIVE:

To determine the prevalence of vancomycin-resistant enterococci (VRE) bowel colonization in hospitalized patients in Manitoba who had stool specimens collected for Clostridium difficile toxin and/or culture testing.

DESIGN:

Two tertiary care and five community hospitals in Winnipeg and three rural Manitoba community hospitals participated in this study. From January 1 to December 31, 1997 stool specimens, one per patient, submitted to hospital microbiology laboratories for C difficile toxin and/or culture testing were screened for VRE on colistin-nalidixic acid-vancomycin (6 μg/mL) (CNAV) agar plates. The study was divided into six, eight-week intervals. Stool specimens received in the first two weeks of each eight week interval were screened for VRE.

MAIN RESULTS:

A total of 1408 stool specimens were submitted over the 48-week study period. Sixty-seven (4.8%) patients with VRE colonization of their lower gastrointestinal tract were identified. Three of the 67 (4.5%) VRE isolates were Enterococcus faecium, with the remaining 64 (95.5%) were Enterococcus gallinarum. The three vancomycin-resistant E faecium -VREF- (from two different Winnipeg hospitals) demonstrated the vanA genotype, and were resistant to vancomycin, teicoplanin and ampicillin. All three VREF isolates also demonstrated high level resistance to both gentamicin and streptomycin but were susceptible to quinuprisitin/dalfopristin and LY333328.

CONCLUSION:

VRE colonization in hospitalized patients in Manitoba is infrequent and most commonly due to E gallinarum. The prevalence of VREF colonization in the patients studied was 0.2% (three of 1408).Key Words: Manitoba, Prevalence, Vancomycin-resistant enterococciVancomycin-resistant Enterococcus faecium (VREF) accounts for up to 65% of E faecium isolates in hospitalized patients across the United States and is endemic in many North American tertiary care institutions (1,2). The management of these infections presents a significant clinical challenge because species of the genus Enterococcus, and in particular E faecium, are frequently resistant to several antimicrobial agents (3). High level penicillin resistance, high level aminoglycoside resistance and most recently vancomycin resistance are emerging as significant concerns in the treatment of enterococcal infections. This has prompted the development and evaluation of new antimicrobial agents such as quinupristin/dalfopristin and LY333328, a glycopeptide, which may offer activity against enterococci resistant to conventional therapy (2).VREF is not endemic in Manitoba hospitals, and infection with VREF is extremely rare (4). However, the prevalence of VREF lower gastrointestinal tract (GIT) carriage, which frequently precedes infection (5,6), is presently unknown for patients hospitalized in Manitoba. To determine whether the lack of VREF endemnicity correlated with an absence of lower GIT colonization, we assessed lower GIT carriage of VREF for patients hospitalized in 10 Manitoba hospitals from January 1 to December 31, 1997. Our study was consistent with Centers for Disease Control and Prevention guidelines (Atlanta, Georgia) that suggest surveillance programs for vancomycin-resistant enterococci (VRE) be undertaken on an intermittent basis in areas where VRE is not known to be endemic (6). Isolates of VREF identified were phenotypically and genotypically characterized, and tested for their susceptibilities against a panel of antimicrobial agents.  相似文献   
89.
90.
From 1990 to 1993 we performed a prospective study of busulfan (16 mg/kg) and cyclophosphamide (120 mg/kg) in 30 patients with refractory anemia (RA) undergoing related (n = 17) or unrelated (n = 13) donor marrow transplantation. Nineteen patients survive disease free (63% 3- year actuarial disease-free survival [DFS]) and no patient relapsed. These results were compared to those of 38 historical controls with RA treated with cyclophosphamide and total body irradiation, of whom 22 are disease-free survivors and 1 relapsed. After correcting for significant variables between the two treatment groups, we found no statistically significant difference in outcome based on preparative regimen. Combining data from these 68 patients plus 2 additional patients with RA treated before 1993 with busulfan and cyclophosphamide, we identified four variables independently associated with improved survival: younger age, shorter disease duration, lower neutrophil count pretransplant, and lower hematocrit pretransplant. We also found that 15 patients 40 to 55 years of age had a 46% 3-year actuarial DFS and 26 patients receiving unrelated or mismatched related donor marrow had a 50% 3-year actuarial DFS. We conclude that there does not appear to be any significant difference in outcome based on preparative regimen in this patient population. In addition, allogeneic bone marrow transplantation may be a reasonable approach to therapy of RA early after diagnosis. However, whether early intervention with transplantation prolongs survival over that expected without transplantation cannot be ascertained with certainty from available data.  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