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   4936篇
  免费   360篇
  国内免费   20篇
耳鼻咽喉   30篇
儿科学   150篇
妇产科学   113篇
基础医学   765篇
口腔科学   132篇
临床医学   389篇
内科学   1193篇
皮肤病学   221篇
神经病学   552篇
特种医学   48篇
外科学   364篇
综合类   22篇
预防医学   424篇
眼科学   159篇
药学   382篇
中国医学   33篇
肿瘤学   339篇
  2024年   3篇
  2023年   40篇
  2022年   98篇
  2021年   178篇
  2020年   106篇
  2019年   172篇
  2018年   181篇
  2017年   131篇
  2016年   152篇
  2015年   165篇
  2014年   221篇
  2013年   265篇
  2012年   444篇
  2011年   433篇
  2010年   243篇
  2009年   192篇
  2008年   351篇
  2007年   308篇
  2006年   283篇
  2005年   298篇
  2004年   263篇
  2003年   239篇
  2002年   239篇
  2001年   21篇
  2000年   20篇
  1999年   41篇
  1998年   30篇
  1997年   27篇
  1996年   23篇
  1995年   16篇
  1994年   8篇
  1993年   13篇
  1992年   13篇
  1991年   10篇
  1990年   9篇
  1989年   3篇
  1988年   3篇
  1987年   10篇
  1986年   10篇
  1984年   5篇
  1983年   3篇
  1982年   9篇
  1981年   4篇
  1980年   3篇
  1978年   4篇
  1977年   3篇
  1974年   3篇
  1972年   3篇
  1970年   3篇
  1967年   3篇
排序方式: 共有5316条查询结果,搜索用时 46 毫秒
121.
122.
The beneficial effects of N-(2-mercaptopropionyl)-glycine (MPG) against ischemia–reperfusion injury in normotensive animals have been previously studied. Our objective was to test the action of MPG during ischemia and reperfusion in hearts from spontaneously hypertensive rats (SHR). Isolated hearts from SHR and age-matched normotensive rats Wistar Kyoto (WKY) were subjected to 50-min global ischemia (GI) and 2-hour reperfusion (R). In other hearts MPG 2 mM was administered during 10 min before GI and the first 10 min of R. Infarct size (IS) was assessed by TTC staining technique and expressed as percentage of risk area. Postischemic recovery of myocardial function was assessed. Reduced glutathione (GSH), thiobarbituric acid reactive substances (TBARS) and SOD cytosolic activity — as estimators of oxidative stress and MnSOD cytosolic activity — as an index of (mPTP) opening were determined. In isolated mitochondria H2O2-induced mPTP opening was also measured. The treatment with MPG decreased infarct size, preserved GSH levels and decreased SOD and MnSOD cytosolic activities, TBARS concentration, and H2O2 induced-mPTP opening in both rat strains. Our results show that in both hypertrophied and normal hearts an attenuation of mPTP opening via reduction of oxidative stress appears to be the predominant mechanism involved in the cardioprotection against reperfusion injury MPG-mediated.  相似文献   
123.
Psychiatric Quarterly - The Coronavirus Disease 2019 (COVID-19) can affect mental health in different ways. There is little research about psychiatric complications in hospitalized patients with...  相似文献   
124.
Hepatitis C infection is associated with autoimmune disorders, such as the production of autoantibodies. Anti-LKM1 and anti-LC1, immunomarkers of type 2 autoimmune hepatitis, have been previously associated with a HCV infection. Anti-Soluble-Liver-Antigen autoantibodies (SLA) are specifically associated with type 1 and type 2 autoimmune hepatitis and more closely related to patients who relapse after steroid therapy. The recent molecular cloning of the soluble liver antigen provides the opportunity to develop more specific tests for the detection of antibodies against it. The aim of this work is to characterize anti-soluble-liver autoantibodies in sera from patients chronically infected by HCV. A recombinant cDNA from activated Jurkat cells coding for the full length tRNP(Ser)Sec/SLA antigen was obtained. ELISA, Western Blot and immunoprecipitation tests were developed and used to search for linear and conformational epitopes recognized by anti-SLA antibodies in sera from patients chronically infected by HCV. Anti-soluble liver antigen antibodies were found in sera from 10.4% of HCV-infected patients. The prevalence was significantly increased to 27% when anti-LKM1 was also present. Most anti-SLA reactivity was directed against conformational epitopes on the antigen. The means titers by ELISA were lower than those obtained in type 2 AIH. The result of autoantibody isotyping showed a subclass restriction to IgG1 and also IgG4. This study shows the presence of anti-SLA antibodies in approximately 10% of HCV infected patients. The prevalence of SLA autoantibodies in HCV infected patients increases when LKM1 autoantibodies are also present. The relationship between the prevalence of this characteristic autoimmune hepatitis autoantibody and the implication of an autoimmune phenomenon in the liver injury of patients chronically infected by HCV needs further investigation.  相似文献   
125.
The non-synonymous mutations arg16gly (rs1042713) and gln27glu (rs1042714) in the adrenergic β-2 receptor gene (ADRB2) have been associated with cognitive function and brain white matter integrity. The current study aimed to replicate these findings and expand them to a broader range of cognitive and brain phenotypes. The sample used is a community-dwelling group of older people, the Lothian Birth Cohort 1936. They had been assessed cognitively at age 11 years, and undertook further cognitive assessments and brain diffusion MRI tractography in older age. The sample size range for cognitive function variables was N = 686–765, and for neuroimaging variables was N = 488–587. Previously-reported findings with these genetic variants did not replicate in this cohort. Novel, nominally significant associations were observed; notably, the integrity of the left arcuate fasciculus mediated the association between rs1042714 and the Digit Symbol Coding test of information processing speed. No significant associations of cognitive and brain phenotypes with ADRB2 variants survived correction for false discovery rate. Previous findings may therefore have been subject to type 1 error. Further study into links between ADRB2, cognitive function and brain white matter integrity is required.  相似文献   
126.
Journal of NeuroVirology - The objective of the present study was to identify the frequency of MS patients in Latin America (LATAM) that received the influenza vaccine during the most recent season...  相似文献   
127.
Journal of Artificial Organs - The precise moment for weaning a patient off extracorporeal membrane oxygenation (ECMO) is not always easy to establish. Also, mechanical causes may obligate to...  相似文献   
128.
ObjectiveFormulate experimental adhesives containing titanium dioxide nanotubes (nt-TiO2) or titanium dioxide nanotubes with a triazine-methacrylate monomer (nt-TiO2:TAT) and evaluate the effect of these fillers on the physical, chemical, and biological properties of the adhesives.MethodsFirst, nt-TiO2 were synthesized via a hydrothermal method. The nt-TiO2 were mixed with a triazine-methacrylate monomer (TAT) to formulate nt-TiO2:TAT, which were characterized by transmission electron microscopy (TEM). The nt-TiO2, TAT, and nt-TiO2:TAT were evaluated via Fourier Transform Infrared, Ultraviolet–visible, and micro-Raman spectroscopies. An experimental adhesive resin was formulated with bisphenol A glycerolate dimethacrylates, 2-hydroxyethyl methacrylate, and photoinitiator/co-initiator system. nt-TiO2 or nt-TiO2:TAT were incorporated at 2.5 wt.% and 5 wt.% in the adhesive. The base resin without nt-TiO2 or nt-TiO2:TAT was used as a control group. The adhesives were evaluated for antibacterial activity, cytotoxicity, polymerization kinetics, degree of conversion (DC), Knoop hardness, softening in solvent (ΔKHN%), ultimate tensile strength (UTS), 24 h- and 1 year- microtensile bond strength (μ-TBS).ResultsTEM confirmed the nanotubular morphology of TiO2. FTIR, UV–vis, and micro-Raman analyses showed the characteristic peaks of each material, indicating the impregnation of TAT in the nt-TiO2. Adhesives with nt-TiO2:TAT showed antimicrobial activity against biofilm formation compared to control (p < 0.05), without differences in the viability of planktonic bacteria (p > 0.05). All groups showed high percentages of pulp cell viability. The polymerization kinetics varied among groups, but all presented DC above 50%. The addition of 5 wt.% of nt-TiO2 and both groups containing nt-TiO2:TAT showed higher values ??of Knoop hardness compared to the control (p < 0.05). The groups with nt-TiO2:TAT presented lower ΔKHN% (p < 0.05) and higher UTS (p < 0.05) than the control group. After one year, the group with 5 wt.% of nt-TiO2, as well as both groups containing nt-TiO2:TAT, showed higher μ-TBS than the control (p < 0.05).SignificanceThe mixing of a triazine-methacrylate monomer with the nt-TiO2 generated a filler that improved the physicochemical properties of the adhesive resins and provided antibacterial activity, which could assist in preventing carious lesions around tooth-resin interfaces. The set of physical, chemical, and biological properties of the formulated polymer, together with the greater stability of the bond strength over time, make nt-TiO2:TAT a promising filler for dental adhesive resins.  相似文献   
129.
130.
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