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   3545篇
  免费   151篇
  国内免费   15篇
耳鼻咽喉   144篇
儿科学   76篇
妇产科学   237篇
基础医学   440篇
口腔科学   41篇
临床医学   232篇
内科学   1066篇
皮肤病学   64篇
神经病学   237篇
特种医学   137篇
外科学   290篇
综合类   34篇
预防医学   119篇
眼科学   52篇
药学   295篇
中国医学   6篇
肿瘤学   241篇
  2024年   3篇
  2023年   22篇
  2022年   138篇
  2021年   221篇
  2020年   79篇
  2019年   89篇
  2018年   125篇
  2017年   74篇
  2016年   94篇
  2015年   98篇
  2014年   114篇
  2013年   177篇
  2012年   293篇
  2011年   282篇
  2010年   152篇
  2009年   117篇
  2008年   210篇
  2007年   252篇
  2006年   220篇
  2005年   231篇
  2004年   206篇
  2003年   198篇
  2002年   158篇
  2001年   26篇
  2000年   10篇
  1999年   8篇
  1998年   14篇
  1997年   12篇
  1996年   17篇
  1995年   6篇
  1992年   14篇
  1991年   6篇
  1990年   3篇
  1989年   5篇
  1987年   2篇
  1986年   2篇
  1985年   4篇
  1984年   1篇
  1983年   5篇
  1982年   5篇
  1981年   2篇
  1980年   2篇
  1979年   5篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
  1940年   1篇
  1938年   1篇
  1936年   1篇
排序方式: 共有3711条查询结果,搜索用时 15 毫秒
81.
Last decade brought great development in the treatment of patients with heart failure (HF). General use of angiotensin-converting-enzyme inhibitors (ACE-I) in patients with asymptomatic left ventricular dysfunction or with HF significantly reduced morbidity and mortality. The aim of this study was to assess how the specialists from Cardiology Department and Gastroenterology Department think that heart failure should be managed, how they implement their knowledge and if it is consistent with the recommendation of European Society of Cardiology (ESC) and whether differences exists in practice between specialists. In the first phase the specialists, cardiologists and diabetologists, answered the questions about the management of different stages of HF. In second phase we analysed medical documentation of 345 patients aged between 38 and 98 years, hospitalised in Cardiology and Gastroenterology Departments from October 2000 to February 2002 by reason of coronary artery disease, hypertension and dilated cardiomyopathy. In the third phase we compared the knowledge of heart failure management from questionnaire and its implementation, the compliance with ESC recommendation and finally whether differences in clinical practice exist between cardiologist and diabetologists. RESULTS: ACE-I were prescribed in all NYHA classes of HF. In over 50% patients in II NYHA class to 94% in IV NYHA class in Cardiology Department. Differences between the Departments in prescribing of ACE-I were observed. Beta-blockers (BB) were used with the same frequency in all NYHA classes, more often in Cardiology Department. Frequency of the administration of digoxin, diuretics, aldosterone receptor blocker was increasing starting with II NYHA class. The highest compliance between declarations from questionnaire and clinical practice concerned the use of BB and ACE-I combination.  相似文献   
82.
Bochowicz A  Styczyński G  Szulc M  Gurba H  Pruszczyk P 《Kardiologia polska》2002,57(12):564-6; discussion 567
A case of a 37-year-old male admitted to the hospital due to dyspnea and chest pain is presented. Electrocardiogram showed negative T waves in V1 and V2 as well as subtle ST segment elevation in all precordial leads. Cardiac enzymes were moderately elevated. The initial diagnosis was myocarditis or acute coronary syndrome, however, transthoracic echocardiography showed a marked right ventricular overload which suggested acute pulmonary embolism. The latter diagnosis was confirmed by transesophageal echocardiography which revealed thrombosis of both left and right pulmonary arteries. The patient received thrombolysis and anticoagulants, and his condition improved. He was discharged home and the course of a six-month follow-up was uneventful.  相似文献   
83.
The aim of this study was to investigate somatic properties and physiological capacity, and analyze kinematic parameters in the 200 m breaststroke swimming race. Twenty-seven male swimmers participated in the study. They were 15.7±1.98 years old. Their average height was 1.80 ± 0.02 m and lean body mass (LBM) was 62.45 ± 8.29 kg. Physiological exercise capacity was measured in two separate 90 sec. all-out tests, one for the arms and second for legs. During the tests total work of arm cranking (TWAR) and cycling (TWLG) as well as peak of VO2 for arm (VO2peakAR) and leg (VO2peakLG) were measured. The underwater swimmers body movements were recorded during the all-out swimming 200m breaststroke speed test using an underwater camera installed on a portable trolley. The swimming kinematic parameters and propulsive or non-propulsive movement phases of the arms and legs as well as average speed (V200), surface speed (V200surface) and swimming speed in turn zones (V200turns) were extracted. V200surface was significantly related to the percentage of leg propulsion and was shown to have large effect on VO2peakLG in the Cohen analysis. V200turns depended significantly on the indicators of physiological performance and body structure: TWAR, VO2peak LG and LBM, LBM, which in turn strongly determined the measured results of TWAR, TWLG, VO2peakAR and VO2peakLG. The V200turns and V200surface were strongly associated with V200, 0.92, p < 0.001 and 0.91, p < 0.001 respectively. In each lap of the 200m swimming there was an increased percentage of propulsion of limb movement observed simultaneously with a reduction in the gliding phase in the breaststroke cycles.

Key points

  • This study investigated the influence of the selected indicators of somatic properties and physiological capacity as well kinematic and coordination parameters on breaststroke swimming.
  • In this observations the body’s functional capacity have an important impact on achieving good breaststroke swimming results, the V200 was moderately associated on VO2peakLG, moreover, separate V200turns depended with VO2peakLG and on LBM and TWAR.
  • The speed of surface breaststroke swimming - V200surface similarly as V200turns had a very strong influence on the end result of V200 , 0.91, p<0.001 and 0.92, p<0.001 respectively.
  • The ability to swim fast on the surface (V200surface) was positively and significantly associated with the percentage time of propulsion generation -LP in the breaststroke cycle.
Key words: Breaststroke swimming, physiological indices, lean body mass, kinematic indices  相似文献   
84.
85.
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   
86.
Pituitary - Although it is well known that acromegaly causes enlargement in the extremities, studies investigating the effects of acromegaly on tendons, muscles and soft tissue are limited. The...  相似文献   
87.
88.
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   
89.
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   
90.
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   
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