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   2684篇
  免费   115篇
  国内免费   7篇
耳鼻咽喉   122篇
儿科学   41篇
妇产科学   164篇
基础医学   335篇
口腔科学   10篇
临床医学   153篇
内科学   970篇
皮肤病学   11篇
神经病学   194篇
特种医学   87篇
外科学   201篇
综合类   13篇
预防医学   95篇
眼科学   23篇
药学   230篇
中国医学   4篇
肿瘤学   153篇
  2024年   3篇
  2023年   17篇
  2022年   127篇
  2021年   198篇
  2020年   59篇
  2019年   60篇
  2018年   94篇
  2017年   57篇
  2016年   58篇
  2015年   75篇
  2014年   80篇
  2013年   136篇
  2012年   210篇
  2011年   203篇
  2010年   101篇
  2009年   75篇
  2008年   161篇
  2007年   204篇
  2006年   164篇
  2005年   181篇
  2004年   166篇
  2003年   172篇
  2002年   129篇
  2001年   14篇
  2000年   4篇
  1999年   6篇
  1998年   9篇
  1997年   7篇
  1996年   9篇
  1995年   3篇
  1993年   1篇
  1992年   2篇
  1991年   4篇
  1989年   1篇
  1988年   1篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1983年   2篇
  1982年   3篇
  1981年   2篇
  1980年   2篇
  1973年   1篇
排序方式: 共有2806条查询结果,搜索用时 31 毫秒
61.
62.
AIM: Epidemiological data show that citizens of small towns and villages have presented worse trends in cardiovascular mortality during the political, social and economic transformation in Poland during past 15 years than citizens of large towns. To try to eliminate these inequalities the Polish 400 Cities Project (P400CP), a large educational and interventional project, was prepared. The project consists of two arms: medical and social interventions. MATERIAL AND METHODS: The main aim of the medical screening intervention in P400CP is to increase detection and control of cardiovascular risk factors in inhabitants of 418 small cities (<8000 inhabitants) and surrounding villages, particularly in men and people of lower education. In 2003 and 2004 the P400CP covered 123 cities. All together, 36 696 subjects aged between 18 and 98 years were examined. In all participants, blood pressure (BP), anthropometric measurements, laboratory tests and questionnaire interviews were performed. The social arm of P400CP is one of multi-level educational intervention. Modern techniques of social psychology and marketing were involved to increase participation in interventions. RESULTS: Only 12.5% of all subjects had normal BP, cholesterol (<190 mg/dl) and glucose (<100 mg/dl in whole capillary blood) levels. During the first screening visit 65.5% of all examined subjects had BP>/=140 mmHg or >/=90 mmHg. The fasting glucose level was increased in 19% of women and 26% of men. Almost two-third of all subjects had a total cholesterol level above the norm. CONCLUSIONS: The prevalence of cardiovascular risk factors in participants of the screening programme P400CP in small towns in Poland was very high. High prevalence and low control of risk factors in participants of the P400CP confirm the decision to target this programme at citizens of small towns and villages.  相似文献   
63.
64.
We report on the comprehensive experimental and theoretical studies of magnetic and electronic structural properties of the Gd0.4Tb0.6Co2 compound crystallization in the cubic Laves phase (C15). We present new results and compare them to those reported earlier. The magnetic study was completed with electronic structure investigations. Based on magnetic isotherms, magnetic entropy change (ΔSM) was determined for many values of the magnetic field change (Δμ0H), which varied from 0.1 to 7 T. In each case, the ΔSM had a maximum around room temperature. The analysis of Arrott plots supplemented by a study of temperature dependency of Landau coefficients revealed that the compound undergoes a magnetic phase transition of the second type. From the M(T) dependency, the exchange integrals between rare-earth R-R (JRR), R-Co (JRCo), and Co-Co (JCoCo) atoms were evaluated within the mean-field theory approach. The electronic structure was determined using the X-ray photoelectron spectroscopy (XPS) method as well as by calculations using the density functional theory (DFT) based Full Potential Linearized Augmented Plane Waves (FP-LAPW) method. The comparison of results of ab initio calculations with the experimental data indicates that near TC the XPS spectrum collects excitations of electrons from Co3d states with different values of exchange splitting. The values of the magnetic moment on Co atoms determined from magnetic measurements, estimated from the XPS spectra, and results from ab initio calculations are quantitatively consistent.  相似文献   
65.
The paper presents the results of research concerning three fiber materials—mineral wool, hemp fiber and wood wool—as loose-fill thermal insulation materials. The analysis used the material parameters determined in previous works conducted by the authors, such as thermal conductivity and air permeability in relation to bulk density. These materials exhibit open porosity; thus, convection is an essential phenomenon in the heat transfer process. The paper aimed at conducting thermal simulations of various frame wall variants which were filled with the above-mentioned insulation materials. The simulations were performed with the Control Volume Method using the Delphin 5.8 software. The studies accounted for the effect of wind pressure and the time of its influence on a wall insulated by means of fiber material with a thickness of 150 as well as 250 mm. The simulation enabled us to obtain such data as maximal R-value reduction and time to return to equilibrium after filtration for the analyzed materials. The study proved that heat transfer in these insulations strongly depends on the bulk density, thickness of the insulation and wind pressure. The decrease in R is reduced as the density increases. This results from the decreased air permeability characterizing the material. Wind washing causes lower R reduction than air filtration in all models. The greater the thickness, the longer it takes for the models to return to the equilibrium state following air filtration (and wind washing). This period is comparable for air filtration and wind washing. Hemp fibers were characterized with the strongest susceptibility to air filtration; in the case of wood wool, it was also high, but lower than for hemp fibers, while mineral wool was characterized with the lowest.  相似文献   
66.
Infections that are triggered by the accompanying immunosuppression in patients with burn wounds are very common regardless of age. Among burn patients, the most frequently diagnosed infections include the bacterial ones primarily caused by Pseudomonas aeruginosa or Klebsiella pneumonia, as well as fungal infections with the etiology of Candida spp. or Aspergillus spp. Besides, burn wounds are highly susceptible to viral infections mainly due to the impaired immune responses and defective functions of the immune cells within the wound microenvironment. The most prevalent viruses that invade burn wounds include herpes simplex virus (HSV), cytomegalovirus (CMV), human papilloma virus (HPV), and varicella zoster virus (VZV). Likewise, less prevalent infections such as those caused by the orf virus or Epstein–Barr Virus (EBV) might also occur in immunosuppressed burn patients. Viral infections result in increased morbidity and mortality rates in severely burned patients. Additionally, a positive correlation between the hospitalization duration and the severity of the viral infection has been demonstrated. Viral infections trigger the occurrence of various complications, ranging from mild symptoms to even fatal incidents. Accurate detection of viral infection is of great clinical importance because of the possibility for a quicker introduction of proper treatment therapy and shortening of hospitalization time. The aim of this paper is to provide a comprehensive review of the literature and summarize the findings regarding the most common viral infections in immunosuppressed burn patients.  相似文献   
67.
68.
69.
70.
A case of a 51-year-old woman with symptoms of non-ST-segment elevation acute coronary syndrome and concomitant atrial flutter is presented. Patient underwent atrioventricular septal defect repair in childhood. Coronary angiography showed total occlusion of left main coronary artery and massive collateral network originating from right coronary artery supplying entire left coronary artery. Ablation of atrial flutter had been performed and patient was subsequently submitted to mitral valve replacement, tricuspid valvuloplasty and coronary artery bypass grafting. The potential causes of left main occlusion are in this case discussed.  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