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   3452542篇
  免费   254076篇
  国内免费   6124篇
耳鼻咽喉   47096篇
儿科学   112877篇
妇产科学   94162篇
基础医学   499878篇
口腔科学   98487篇
临床医学   314527篇
内科学   665093篇
皮肤病学   77237篇
神经病学   273110篇
特种医学   129400篇
外国民族医学   704篇
外科学   519166篇
综合类   76132篇
现状与发展   14篇
一般理论   1277篇
预防医学   268229篇
眼科学   83073篇
药学   255328篇
  12篇
中国医学   7553篇
肿瘤学   189387篇
  2021年   27026篇
  2019年   27929篇
  2018年   39228篇
  2017年   29584篇
  2016年   33073篇
  2015年   37366篇
  2014年   52622篇
  2013年   78539篇
  2012年   108309篇
  2011年   114821篇
  2010年   68462篇
  2009年   64221篇
  2008年   107158篇
  2007年   114189篇
  2006年   115462篇
  2005年   111405篇
  2004年   107205篇
  2003年   102743篇
  2002年   99163篇
  2001年   163220篇
  2000年   167581篇
  1999年   140549篇
  1998年   39972篇
  1997年   34938篇
  1996年   35129篇
  1995年   33326篇
  1994年   30636篇
  1993年   28653篇
  1992年   108409篇
  1991年   105361篇
  1990年   102090篇
  1989年   98511篇
  1988年   90351篇
  1987年   88445篇
  1986年   83206篇
  1985年   79628篇
  1984年   59139篇
  1983年   50403篇
  1982年   29431篇
  1979年   53804篇
  1978年   37971篇
  1977年   31867篇
  1976年   30227篇
  1975年   32144篇
  1974年   38926篇
  1973年   37275篇
  1972年   34808篇
  1971年   32707篇
  1970年   30363篇
  1969年   28690篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
Coronary embolism (CE) is an uncommon and unique cause of acute myocardial infarction. In this report, we review 216 cases of CE including 2 new cases from our institution. The mean patient age was 52.5 years and 62% of the patients were males. Chest pain was the most common presenting symptom followed by dyspnea, and the most commonly affected vessel was the left anterior descending artery. Leading etiologies of the embolus were atrial fibrillation, septic emboli, and iatrogenic causes. Treatment approaches varied with thrombus aspiration being used in 30% of cases. In-hospital mortality rate was 36% and 13% of the cases were complicated by cerebrovascular accident. CE is a unique pathology that leads to acute myocardial infarction. It portends a high mortality rate and requires a high level of suspicion as symptoms may be misleading. Further research is needed in order to improve recognition and management and to lower associated mortality.  相似文献   
55.
Krishna S. Iyer 《Platelets》2020,31(4):474-482
Abstract

Platelets are small, anucleated effector cells that play an important role in linking the hemostatic and inflammatory processes in the body. Platelet function is known to be altered under various inflammatory conditions including aging. A gain in platelet function during aging can increase the risk of thrombotic events, such as stroke and acute myocardial infarction. Anti-platelet therapy is designed to reduce risk of serious cerebrovascular and cardiovascular events, but the adverse consequences of therapy, such as risk for bleeding increases with aging as well. Age-associated comorbidities such as obesity, diabetes, and hyperlipidemia also contribute to increased platelet activity and thus can enhance the risk of thrombosis. Therefore, identification of unique mechanisms of platelet dysfunction in aging and in age-associated comorbidities is warranted to design novel antiplatelet drugs. This review outlines some of the current areas of research on aging-related mechanisms of platelet hyperactivity and addresses the clinical urgency for designing anti-platelet therapies toward novel molecular targets in the aging population.  相似文献   
56.
Abstract

Objective: This study aims at identifying associations between cognitive function and suicidal ideation in the sample of patients with anxiety and mood disorders (AMD).

Methods: In sum, 186 (age = 39?±?12.3 years; 142 [76.3%] females) patients with AMD were enrolled in the study. Assessment included evaluation of socio-demographic information, medication use, anxiety and depression symptoms. Cognitive tests included measures of psychomotor performance and incidental learning using the Digit Symbol Test. Trail Making Tests respectively measured perceptual speed, task-switching and executive control. Additionally, 21 patients completed tests from the Cambridge Automated Neuropsychological Test Battery measuring set shifting (Interdimensional/extradimensional set-shift), executive planning (Stockings of Cambridge), and decision making (Cambridge Gamble Task [CGT]).

Results: Almost half (45.0%, n?=?86) of the study sample patients had experienced suicidal ideations. In multivariable regression analysis, suicidal ideation was associated with a greater overall proportion of bet and risk taking on the CGT task (β?=?0.726, p?=?.010 and β?=?0.634, p?=?.019), when controlling for socio-demographic characteristics, medication use, anxiety and depression symptoms.

Conclusions: Outpatients with AMD and suicidal ideation could be distinguished by the presence of cognitive deficits in the executive function domain, particularly in impulse-control and risk taking.  相似文献   
57.
58.
59.
The purpose of this investigation was to characterize noise levels in spaces designated as “effective quiet” areas on a U.S. Navy aircraft carrier. Noise dosimetry samples were collected in 15 designated spaces, representing 15 noise measurements, while at-sea during airwing carrier qualifications. Equivalent sound level (Leq) measurements were collected during flight operations (Leq (flt ops)), non-flight operations (Leq (non-flt ops)), and over 24-hr periods (Leq (24-hr)). These data were compared to the 70 dBA American Conference of Governmental Industrial Hygienists (ACGIH®) Threshold Limit Value (TLV®) for “effective quiet” areas intended for temporary threshold shift recovery when personnel live and work in a potentially noise hazardous environment for periods greater than 24?hr. The monitored areas were selected based on personnel occupancy/use during off-duty time periods. Areas were classified by either (1) leisure areas that included mess (eating areas), gyms, lounges, an internet cafe, and the fantail social area or (2) berthing (sleeping) areas. The Leq measurements in decibels “A” weighted (dBA) were compared to determine significant differences between Leq (flt ops), Leq (non-flt ops), and Leq (24-hr) and were compared between leisure area and berthing area. Measured noise levels according to time period ranged as follows: (1) Leq (24-hr): 70.8–105.4 dBA; (2) Leq (flt ops): 70–101.2 dBA; and (3) Leq (non-flt ops): 39.4–104.6 dBA. All area measurements over the 24-hr period and during flight operations and 46.7% of the areas during the non-flight operation time period exceeded the “effective quiet” 70 dBA ACGIH TLV. Mean Leqs were 15 dBA higher during flight operations compared to non-flight operations in “effective quiet” areas (p?=?0.001). The Leqs in leisure areas were significantly higher than berthing areas by approximately 21 dBA during non-flight operation periods (p?=?0.001). Results suggest noise levels in “effective quiet” areas frequented by aircraft carrier personnel during off-duty hours when at-sea may inhibit auditory recovery from occupational noise exposures that occur on-duty.  相似文献   
60.
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