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   2402619篇
  免费   187749篇
  国内免费   9812篇
耳鼻咽喉   30717篇
儿科学   78430篇
妇产科学   65656篇
基础医学   340930篇
口腔科学   66110篇
临床医学   226366篇
内科学   476053篇
皮肤病学   52982篇
神经病学   199497篇
特种医学   92656篇
外国民族医学   622篇
外科学   353784篇
综合类   55679篇
现状与发展   3篇
一般理论   894篇
预防医学   201716篇
眼科学   52224篇
药学   172849篇
  11篇
中国医学   4924篇
肿瘤学   128077篇
  2018年   26670篇
  2017年   20557篇
  2016年   23438篇
  2015年   26551篇
  2014年   36853篇
  2013年   56368篇
  2012年   72717篇
  2011年   77798篇
  2010年   46851篇
  2009年   44511篇
  2008年   71700篇
  2007年   76015篇
  2006年   77233篇
  2005年   74674篇
  2004年   71226篇
  2003年   68500篇
  2002年   65726篇
  2001年   109847篇
  2000年   112927篇
  1999年   94825篇
  1998年   28323篇
  1997年   25478篇
  1996年   26052篇
  1995年   25655篇
  1994年   24024篇
  1993年   22517篇
  1992年   77543篇
  1991年   75724篇
  1990年   73054篇
  1989年   69443篇
  1988年   64511篇
  1987年   63234篇
  1986年   60086篇
  1985年   57792篇
  1984年   44051篇
  1983年   37149篇
  1982年   22987篇
  1981年   20521篇
  1980年   19225篇
  1979年   39810篇
  1978年   28834篇
  1977年   23963篇
  1976年   22794篇
  1975年   23531篇
  1974年   28203篇
  1973年   27249篇
  1972年   25179篇
  1971年   23334篇
  1970年   21437篇
  1969年   19861篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
SETTING: Tuberculosis (TB) is frequent in human immunodeficiency virus (HIV) infected patients, but its treatment is hampered by adverse events and paradoxical reactions. OBJECTIVE: To examine the impact of HIV infection and other factors on the risk and spectrum of adverse events related to anti-tuberculosis treatment in a prospective cohort study conducted between January 2003 and August 2004. RESULTS: Of 105 patients treated for TB, 30 were HIV-infected. The overall incidence of adverse events was 122.5 +/- 18.5 per 100 patient-years (py) and the incidence of severe adverse events was 45.2 +/- 11.3/100 py. Age >50 years (OR 2.2, 95%CI 1.01-4.8, P = 0.046) and HIV infection (OR 3.9, 95%CI 2.1-7.5, P < 0.001) were independently associated with a higher risk of adverse events. Hepatitis (30.5/100 py) and neuropathy (28.6/100 py) were the most frequent adverse events. Hepatitis C virus infection was associated with hepatitis (OR 4.2, 95%CI 1.2-15.0, P = 0.028) and neuropathy with HIV infection (OR 3.8, 95%CI 1.1-13.7, P = 0.040). CONCLUSION: Adverse reactions to anti-tuberculosis drugs are frequent. HIV infection and age >50 years are factors associated with such reactions, while hepatitis C virus infection is a risk factor for hepatitis.  相似文献   
962.
963.
Laboratory routines cause animal stress.   总被引:8,自引:0,他引:8  
Eighty published studies were appraised to document the potential stress associated with three routine laboratory procedures commonly performed on animals: handling, blood collection, and orogastric gavage. We defined handling as any non-invasive manipulation occurring as part of routine husbandry, including lifting an animal and cleaning or moving an animal's cage. Significant changes in physiologic parameters correlated with stress (e.g., serum or plasma concentrations of corticosterone, glucose, growth hormone or prolactin, heart rate, blood pressure, and behavior) were associated with all three procedures in multiple species in the studies we examined. The results of these studies demonstrated that animals responded with rapid, pronounced, and statistically significant elevations in stress-related responses for each of the procedures, although handling elicited variable alterations in immune system responses. Changes from baseline or control measures typically ranged from 20% to 100% or more and lasted at least 30 min or longer. We interpret these findings to indicate that laboratory routines are associated with stress, and that animals do not readily habituate to them. The data suggest that significant fear, stress, and possibly distress are predictable consequences of routine laboratory procedures, and that these phenomena have substantial scientific and humane implications for the use of animals in laboratory research.  相似文献   
964.
965.
X Dong  M He  X Song  B Lu  Y Yang  S Zhang  N Zhao  L Zhou  Y Li  X Zhu  R Hu 《Diabetic medicine》2007,24(12):1482-1486
AIMS: Our aim was to assess performances of the Cockcroft-Gault and simplified Modification of Diet in Renal Disease (MDRD) formulae in estimating glomerular filtration rate (GFR) in Chinese diabetic populations and their association with vascular risks. METHODS: A total of 1009 patients with Type 2 diabetes were categorized into low estimated GFR groups (GFR < 60 ml/min/1.73 m(2)) and control groups by the two equations. The performances of these formulae were assessed at different stages of kidney function. Carotid artery intima-media thickness (IMT) and the prevalence of diabetic retinopathy or albuminuria were compared among the groups. The ability of these formulae to identify established vascular risk markers using sensitivity, specificity, positive and negative predictive values were also compared. RESULTS: The prevalence of low estimated GFR was 32.7% with the Cockcroft-Gault formula and 5.2% with the MDRD formula, respectively. In low estimated GFR subjects by the MDRD formula, IMT was significantly thicker than those by the Cockcroft-Gault formula (1.2 mm vs. 1.0 mm; P < 0.05), with a higher prevalence of albuminuria (78.4 vs. 52.8%, P < 0.05) and diabetic retinopathy (46.5 vs. 30.5%; P < 0.05). The Cockcroft-Gault formula gave a specificity of 71.7% and a sensitivity of 37.0%, and the MDRD formula gave a specificity of 96.6% and a sensitivity of 7.9% in estimating low GFR relevant for established vascular risks. CONCLUSIONS: These formulae performed differently in Chinese diabetic populations. The simplified MDRD formula is minimally superior to the Cockcroft-Gault formula for its high specificity and positive predictive values in estimating low GFR relevant for vascular risks.  相似文献   
966.
967.
968.
969.
D G Wilson  H Rees  M H Roberts 《Pain》1991,44(2):195-200
Four behavioural tests have been used to study the antinociceptive effects of electrical stimulation of the anterior pretectal nucleus (APtN) in the rat. The antinociceptive effects of stimulating this nucleus, which lies dorsally in the posterior diencephalon, have recently been studied extensively but always using briefly applied heat stimuli. It is reported here that APtN stimulation effectively inhibited responses to briefly applied noxious pressure and longer-lasting noxious chemical (formalin) stimuli. Although the tail-flick reflex to noxious heat was very potently depressed by APtN stimulation, responses to noxious heat in the hot-plate test were not. Three doses of morphine were also studied with each test and it was concluded that 15 sec of 35 microA r.m.s. current into the APtN was as effective as 3-5 mg/kg morphine s.c. in the rat.  相似文献   
970.
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