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   2438404篇
  免费   196920篇
  国内免费   8214篇
耳鼻咽喉   31996篇
儿科学   80148篇
妇产科学   68264篇
基础医学   340217篇
口腔科学   66735篇
临床医学   221427篇
内科学   490462篇
皮肤病学   57903篇
神经病学   202696篇
特种医学   96215篇
外国民族医学   708篇
外科学   370388篇
综合类   58142篇
现状与发展   4篇
一般理论   839篇
预防医学   195902篇
眼科学   54021篇
药学   171276篇
  6篇
中国医学   5024篇
肿瘤学   131165篇
  2018年   26565篇
  2017年   20578篇
  2016年   23938篇
  2015年   26786篇
  2014年   37709篇
  2013年   56372篇
  2012年   72695篇
  2011年   77856篇
  2010年   47213篇
  2009年   45501篇
  2008年   72297篇
  2007年   76689篇
  2006年   77911篇
  2005年   75632篇
  2004年   72252篇
  2003年   69501篇
  2002年   66556篇
  2001年   118693篇
  2000年   121751篇
  1999年   101392篇
  1998年   29927篇
  1997年   26928篇
  1996年   27703篇
  1995年   27083篇
  1994年   24902篇
  1993年   23431篇
  1992年   80362篇
  1991年   77582篇
  1990年   74556篇
  1989年   70968篇
  1988年   65554篇
  1987年   64183篇
  1986年   60326篇
  1985年   57965篇
  1984年   44213篇
  1983年   37354篇
  1982年   23158篇
  1981年   20717篇
  1980年   19268篇
  1979年   39593篇
  1978年   28355篇
  1977年   23751篇
  1976年   22021篇
  1975年   22829篇
  1974年   27138篇
  1973年   26101篇
  1972年   24370篇
  1971年   22331篇
  1970年   20846篇
  1969年   19397篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
BACKGROUND Metabolic disturbances including changes in serum calcium,magnesium or phosphate(P) influence the prevalence of type 2 diabetes mellitus(DM).We assessed the importance of serum P in elderly patients with type 2 DM vs nondiabetes mellitus(non-DM) in relation to renal function.AIM To determine the association between serum P and serum glucose or insulin resistance in diabetic and non-diabetic patients.METHODS One hundred-ten subjects with a mean age of 69.02±14.3 years were enrolled.Twenty-nine of the participants had type 2 DM(26.4%).The incidence of hypertension,smoking and receiving vitamin D(vitD) derivates were recorded.The participants were classified by both estimated glomerular filtration rate(eGFR) and albuminuria categories according to the Kidney Disease Improving Global Outcomes 2012 criteria.RESULTS We divided the patients in two groups according to the P cut-off point related to DM value.A comparison between high and low P showed that body mass index30.2±6.3 vs 28.1±4.6(P=0.04),mean glucose 63.6 vs 50.2(P=0.03),uric acid 6.7±1.6 vs 6.09±1.7(P=0.05),mean intact-parathyroid hormone 68.06 vs 47.4(P=0.001),systolic blood pressure 147.4±16.7 vs 140..2±16.1(P=0.02),mean albuminuria 63.2 vs 50.6(P=0.04) and eGFR 45.6±22.1 vs 55.4±21.5(P=0.02)were significantly different.χ~2 tests showed a significant association between high P and DM,hypertension,receiving vitD,smoking and eGFR stage(χ~2=6.3,P=0.01,χ~2=3.9,P=0.03,χ~2=6.9,P=0.009,χ~2=7.04,P=0.01 and χ~2=7.36,P=0.04,respectively).The adjusted model showed that older age,female gender and increased body mass index were significant predictors of type 2 DM when entering the covariates.CONCLUSION High serum P contributes to vascular and metabolic disturbances in elderly patients with type 2 DM and renal impairment.  相似文献   
73.
74.
75.
76.
77.
78.
Advancement in microelectromechanical system has facilitated the microfabrication of polymeric substrates and the development of the novel class of controlled drug delivery devices. These vehicles have specifically tailored three dimensional physical and chemical features which together, provide the capacity to target cell, stimulate unidirectional controlled release of therapeutics and augment permeation across the barriers. Apart from drug delivery devices microfabrication technology’s offer exciting prospects to generate biomimetic gastrointestinal tract models. BioMEMS are capable of analysing biochemical liquid sample like solution of metabolites, macromolecules, proteins, nucleic acid, cells and viruses. This review summarized multidisciplinary application of biomedical microelectromechanical systems in drug delivery and its potential in analytical procedures.  相似文献   
79.
Children who expect they can bring about good outcomes and avoid bad outcomes tend to experience more personal successes. Little is known about factors that contribute to these ‘control expectancies’. The purpose of the present study was to determine whether children's internal control expectancies occur in the context of parents’ internal control expectancies, low family strain, and high family cohesiveness and whether these factors are more strongly related to daughters’ than sons’ control expectancies. A community sample of 85 children aged 9–11 years and their parents (85 mothers; 63 fathers) completed rating scales. Fathers’ more internal control expectancies and mothers’ reports of fewer family strains were associated with daughters’ but not sons’ greater internal control expectancies, and greater family cohesiveness was related to both daughters’ and sons’ internal control orientations. These findings suggest that family factors may contribute to children's, particularly daughters’, development of internal control expectancies.  相似文献   
80.
Objective: Polyunsaturated fatty acids n-3 (PUFA n-3) have shown effects in reducing tumor growth, in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) abundantly present in fish oil (FO). When these fatty acids are provided in the diet, they alter the functions of the cells, particularly in tumor and immune cells. However, the effects of α-linolenic fatty acid (ALA), which is the precursor of EPA and DHA, are controversial. Thus, our objective was to test the effect of this parental fatty acid. Methods: Non-tumor-bearing and tumor-bearing Wistar rats (70 days) were supplemented with 1 g/kg body weight of FO or Oro Inca® (OI) oil (rich in ALA). Immune cells function, proliferation, cytokine production, and subpopulation profile were evaluated. Results: We have shown that innate immune cells enhanced phagocytosis capacity, and increased processing and elimination of antigens. Moreover, there was a decrease in production of pro-inflammatory cytokines (tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6)) by macrophages. Lymphocytes showed decreased proliferation capacity, increased cluster of differentiation 8 (CD8+) subpopulation, and increased TNF-α production. Conclusions: Oil rich in ALA caused similar immune modulation in cancer when compared with FO.  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