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   2011128篇
  免费   164159篇
  国内免费   7698篇
耳鼻咽喉   27316篇
儿科学   62548篇
妇产科学   56460篇
基础医学   280605篇
口腔科学   57054篇
临床医学   179903篇
内科学   401996篇
皮肤病学   45466篇
神经病学   164891篇
特种医学   82024篇
外国民族医学   431篇
外科学   314783篇
综合类   51384篇
现状与发展   4篇
一般理论   653篇
预防医学   160738篇
眼科学   45193篇
药学   144011篇
  5篇
中国医学   3541篇
肿瘤学   103979篇
  2018年   19257篇
  2016年   17956篇
  2015年   20432篇
  2014年   28746篇
  2013年   43322篇
  2012年   54672篇
  2011年   58328篇
  2010年   35727篇
  2009年   34513篇
  2008年   54773篇
  2007年   58894篇
  2006年   59782篇
  2005年   58092篇
  2004年   56011篇
  2003年   54321篇
  2002年   51748篇
  2001年   90931篇
  2000年   93338篇
  1999年   78357篇
  1998年   23971篇
  1997年   21589篇
  1996年   22304篇
  1995年   21998篇
  1994年   20694篇
  1993年   19492篇
  1992年   65778篇
  1991年   64257篇
  1990年   62174篇
  1989年   59401篇
  1988年   55429篇
  1987年   54600篇
  1986年   51569篇
  1985年   49970篇
  1984年   38407篇
  1983年   32539篇
  1982年   20573篇
  1981年   18721篇
  1980年   17626篇
  1979年   36363篇
  1978年   26346篇
  1977年   22236篇
  1976年   20415篇
  1975年   21730篇
  1974年   26152篇
  1973年   25042篇
  1972年   23520篇
  1971年   21649篇
  1970年   20222篇
  1969年   19285篇
  1968年   17702篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
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   
33.
ABSTRACT

Purpose

To investigate the expression of IL-11 and its receptor IL-11Rα and to quantify density of CD163+ M2 macrophages in proliferative diabetic retinopathy (PDR).  相似文献   
34.
35.
36.
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   
37.
Individuals with sudden unilateral deafness offer a unique opportunity to study plasticity of the binaural auditory system in adult humans. Stimulation of the intact ear results in increased activity in the auditory cortex. However, there are no reports of changes at sub-cortical levels in humans. Therefore, the aim of the present study was to investigate changes in sub-cortical activity immediately before and after the onset of surgically induced unilateral deafness in adult humans. Click-evoked auditory brainstem responses (ABRs) to stimulation of the healthy ear were recorded from ten adults during the course of translabyrinthine surgery for the removal of a unilateral acoustic neuroma. This surgical technique always results in abrupt deafferentation of the affected ear. The results revealed a rapid (within minutes) reduction in latency of wave V (mean pre = 6.55 ms; mean post = 6.15 ms; p < 0.001). A latency reduction was also observed for wave III (mean pre = 4.40 ms; mean post = 4.13 ms; p < 0.001). These reductions in response latency are consistent with functional changes including disinhibition or/and more rapid intra-cellular signalling affecting binaurally sensitive neurons in the central auditory system. The results are highly relevant for improved understanding of putative physiological mechanisms underlying perceptual disorders such as tinnitus and hyperacusis.  相似文献   
38.
DNA methylation at CpG dinucleotides is an important epigenetic regulator common to virtually all mammalian cell types, but recent evidence indicates that during early postnatal development neuronal genomes also accumulate uniquely high levels of two alternative forms of methylation, non-CpG methylation and hydroxymethylation. Here we discuss the distinct landscape of DNA methylation in neurons, how it is established, and how it might affect the binding and function of protein readers of DNA methylation. We review studies of one critical reader of DNA methylation in the brain, the Rett syndrome protein methyl CpG-binding protein 2 (MeCP2), and discuss how differential binding affinity of MeCP2 for non-CpG and hydroxymethylation may affect the function of this methyl-binding protein in the nervous system.  相似文献   
39.
40.
We present a patient with both dynamic left ventricular outflow tract obstruction and valvular aortic stenosis. The aortic valve was calcified, and velocities and gradients measured by continuous‐wave Doppler met standard criteria for severe aortic stenosis. The increased subvalvular velocities invalidated assumptions of the simplified Bernoulli equation; correction using the longer form of the Bernoulli equation suggested a lower but still significant gradient. The complex shape of the subvalvular spectral Doppler envelope indicated supranormal systolic function and dynamic left ventricular outflow obstruction. Left heart catheterization with an end‐hole catheter was required to determine the subvalvular and valvular components of the obstruction.  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