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   1075641篇
  免费   71777篇
  国内免费   1369篇
耳鼻咽喉   15023篇
儿科学   34663篇
妇产科学   28657篇
基础医学   153556篇
口腔科学   29563篇
临床医学   94963篇
内科学   203730篇
皮肤病学   24410篇
神经病学   81542篇
特种医学   42996篇
外国民族医学   201篇
外科学   163217篇
综合类   21741篇
现状与发展   1篇
一般理论   264篇
预防医学   74644篇
眼科学   24551篇
药学   86172篇
  7篇
中国医学   2808篇
肿瘤学   66078篇
  2019年   7777篇
  2018年   11306篇
  2017年   8915篇
  2016年   10104篇
  2015年   11268篇
  2014年   15278篇
  2013年   22208篇
  2012年   30573篇
  2011年   32319篇
  2010年   18965篇
  2009年   17833篇
  2008年   29979篇
  2007年   32105篇
  2006年   32728篇
  2005年   31053篇
  2004年   29752篇
  2003年   28581篇
  2002年   27557篇
  2001年   60046篇
  2000年   61500篇
  1999年   50949篇
  1998年   12460篇
  1997年   11007篇
  1996年   11026篇
  1995年   10332篇
  1994年   9351篇
  1993年   8862篇
  1992年   37817篇
  1991年   36288篇
  1990年   35763篇
  1989年   34311篇
  1988年   30882篇
  1987年   30005篇
  1986年   28229篇
  1985年   26466篇
  1984年   19201篇
  1983年   16129篇
  1982年   8829篇
  1979年   17043篇
  1978年   11410篇
  1977年   10234篇
  1976年   8847篇
  1975年   10074篇
  1974年   11662篇
  1973年   11287篇
  1972年   10765篇
  1971年   10105篇
  1970年   9261篇
  1969年   8953篇
  1968年   7926篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
OBJECTIVE: To determine whether under-reporting of rheumatic fever occurs at hospital, municipal, provincial and national levels of the South African health system. BACKGROUND: Information on the incidence of rheumatic fever (RF) and the prevalence of rheumatic heart disease (RHD) is required for the prevention of valvular heart disease in developing countries. In South Africa, RF was made a notifiable condition in 1989. It has recently been suggested that the reporting of RF cases may be incomplete, possibly because of underreporting by health care professionals and deficient administration of the disease notification system in South Africa. METHOD AND RESULTS: We assessed whether underreporting of RF cases occurs by comparing the numbers of RF cases reported per year at hospital, municipal, provincial and national levels from 1990 to 2004. There was a fall in the number of RF cases reported per year at national and provincial level over the 15 years of observation. A detailed analysis of the number of RF cases reported at hospital, municipal and provincial level for a 5-year period showed that more cases were diagnosed in one hospital (serving a smaller population) than were captured at municipal and provincial level (serving a larger population), suggesting underreporting by health care professionals. There were discrepancies in the number of cases reported at municipal, provincial and national level, suggesting poor administration of the notification system. CONCLUSION: There appears to be underreporting of RF cases by health care professionals, and poor administration of the RF notification system. Health care professionals need to be educated about the statutory requirement to notify all RF cases in South Africa. An effective national disease notification system is required.  相似文献   
82.
83.
84.
85.
INTRODUCTION: Vasopressin, mainly through the V1a-receptor, is thought to be a major player in the maintenance of hyperfiltration. Its inhibition could therefore lead to a decrease in progression of chronic renal failure. To this end, the effect of the vasopressin V1a-receptor-selective antagonist, YM218, was studied on proteinuria and focal glomerulosclerosis in early and late intervention after 5/6 nephrectomy in rats, and compared with an angiotensin-converting enzyme inhibitor (ACE-I). MATERIALS AND METHODS: After 5/6 nephrectomy, early intervention was performed between week 2 and 10 thereafter with the V1a-receptor-selective antagonist (VRA, 10 mg/kg/day, n=10), enalapril (ACE-I, 10 mg/kg/day, n=9), or vehicle (n=8). Late intervention was performed in another group between week 6 and 12 with VRA (10 mg/kg/day, n=7), lisinopril (ACE-I, 5 mg/kg/day, n=7), or vehicle (n=7). RESULTS: In early intervention, proteinuria and focal glomerulosclerosis were significantly decreased by VRA compared to vehicle (44+7% and 59+8% respectively). ACE-I significantly decreased proteinuria (67+7%) and a trend towards a decrease in focal glomerulosclerosis was observed (30+18%). In late intervention, VRA did not decrease proteinuria and focal glomerulosclerosis compared to vehicle (21+20% and 0%, respectively), ACE-I significantly lowered proteinuria (92+2%) and a focal glomerulosclerosis (69+1%) lowering trend was observed. CONCLUSION: These results indicate that VRA may protect against early progression of renal injury after 5/6 nephrectomy, whereas its effectiveness seems limited in established renal damage.  相似文献   
86.
87.
Both vascular surgery and endovascular interventions traumatise the arterial wall, especially the endothelium. The vessel responds with neointimal hyperplasia and/or constrictive remodelling, and this is still the limiting factor in curative interventions. Stent placement prevents constrictive remodelling but is the main trigger for in-stent restenosis. Hyperproliferation of neointimal tissue is the main response to arterial thrombosis, local inflammation or medio-intimal injury such as occurs, for example, after balloon dilatation in the region of arterial anastomoses or of a thrombectomy (Fogarty-manoeuvre). At present, research on prevention of restenosis is focused on inhibiting neointimal hyperproliferation by using drug-eluting stents, and especially sirolimus- or paclitaxel-eluting stents. In addition, further experimental research work is in progress, with the aim of esablishing new treatment regimens and solving the problem of neointimal formation, thrombosis and constrictive remodelling. These include both local and systemic pharmacological therapy, brachy- and laser therapy, and many genetic treatment options, some of which are currently the subjects of experimental studies and early-stage clinical trials. Gene therapy seems like a promising way of preventing restenosis, but has not yet been tested in clinical trials. In the near future, selective, simultaneous, and perhaps even polyphasic regulation for gene silencing of two or more genes involved in the development of restenosis could improve the long-term patency rate.  相似文献   
88.
89.
90.
Mycophenolate mofetil (MMF) used in a triple-drug regimen has been shown to decrease acute rejection rates, compared to a double-drug regimen. The impact of MMF on late acute rejection (LAR) episodes has not been well described. To investigate the risk of LAR (rejection > or = 6 months post-transplantation) data from the Scientific Registry of Transplant Recipients (SRTR) were used. We studied adult primary liver transplant recipients transplanted between June 1, 1995, and April 30, 2004, with hepatitis C virus (HCV) (n = 3356), hepatitis B virus (HBV) (n = 550) or a nonviral (n = 5740) primary cause of liver disease who were recorded as receiving continuous 3-(MMF + Tacro + steroids) versus 2-drug (Tacro + steroids) therapy for at least 6 months immediately post transplantation. Kaplan-Meier analysis showed significantly lower LAR rates 4 years post-transplant in 3- versus 2-drug HCV, HBV and nonviral disease patients. Multivariate regression confirmed 3- versus 2-drug therapy to be associated with a decreased risk of LAR. Late graft survival was significantly lower at 4 years post-transplant for patients with LAR 6-12 months post-transplantation versus patients with early rejection (78.0% vs. 87.0%, p < 0.001) and no rejection (88.1%, p < 0.001). Three-drug versus 2-drug therapy for a minimum of 6 months may offer a better treatment strategy to avoid the consequences and expense of LAR episodes.  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