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   36819篇
  免费   3810篇
  国内免费   128篇
耳鼻咽喉   355篇
儿科学   1291篇
妇产科学   1066篇
基础医学   5252篇
口腔科学   592篇
临床医学   5191篇
内科学   7491篇
皮肤病学   788篇
神经病学   3827篇
特种医学   951篇
外国民族医学   5篇
外科学   3924篇
综合类   463篇
一般理论   17篇
预防医学   3783篇
眼科学   614篇
药学   2429篇
中国医学   36篇
肿瘤学   2682篇
  2023年   283篇
  2022年   367篇
  2021年   981篇
  2020年   767篇
  2019年   1124篇
  2018年   1302篇
  2017年   1003篇
  2016年   1071篇
  2015年   1122篇
  2014年   1443篇
  2013年   1994篇
  2012年   2544篇
  2011年   2425篇
  2010年   1494篇
  2009年   1352篇
  2008年   2100篇
  2007年   2071篇
  2006年   1988篇
  2005年   1900篇
  2004年   1727篇
  2003年   1574篇
  2002年   1478篇
  2001年   556篇
  2000年   527篇
  1999年   528篇
  1998年   371篇
  1997年   309篇
  1996年   246篇
  1995年   252篇
  1994年   235篇
  1993年   194篇
  1992年   329篇
  1991年   333篇
  1990年   322篇
  1989年   276篇
  1988年   294篇
  1987年   268篇
  1986年   294篇
  1985年   253篇
  1984年   230篇
  1983年   224篇
  1982年   188篇
  1981年   183篇
  1980年   135篇
  1979年   209篇
  1978年   163篇
  1977年   139篇
  1976年   158篇
  1975年   141篇
  1974年   151篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
BACKGROUND: Recently, epidemiological and clinical data have revealed important changes with regard to clinical adenovirus infection, including alterations in antigenic presentation, geographical distribution, and virulence of the virus. METHODS: In an effort to better understand the epidemiology of clinical adenovirus infection in the United States, we adopted a new molecular adenovirus typing technique to study clinical adenovirus isolates collected from 22 medical facilities over a 25-month period during 2004-2006. A hexon gene sequence typing method was used to characterize 2237 clinical adenovirus-positive specimens, comparing their sequences with those of the 51 currently recognized prototype human adenovirus strains. In a blinded comparison, this method performed well and was much faster than the classic serologic typing method. RESULTS: Among civilians, the most prevalent adenovirus types were types 3 (prevalence, 34.6%), 2 (24.3%), 1 (17.7%), and 5 (5.3%). Among military trainees, the most prevalent types were types 4 (prevalence, 92.8%), 3 (2.6%), and 21 (2.4%). CONCLUSIONS: For both populations, we observed a statistically significant increasing trend of adenovirus type 21 detection over time. Among adenovirus isolates recovered from specimens from civilians, 50% were associated with hospitalization, 19.6% with a chronic disease condition, 11% with a bone marrow or solid organ transplantation, 7.4% with intensive care unit stay, and 4.2% with a cancer diagnosis. Multivariable risk factor modeling for adenovirus disease severity found that age <7 years (odds ratio [OR], 3.2; 95% confidence interval [CI], 1.4-7.4), chronic disease (OR, 3.6; 95% CI, 2.6-5.1), recent transplantation (OR, 2.7; 95% CI, 1.3-5.2), and adenovirus type 5 (OR, 2.7; 95% CI, 1.5-4.7) or type 21 infection (OR, 7.6; 95% CI, 2.6-22.3) increased the risk of severe disease.  相似文献   
83.
BACKGROUND: Coronary vasculopathy is the main cause of cardiac graft failure. Because yearly coronary angiography is invasive in children, a non-invasive method for detecting graft vasculopathy is needed. The aim of this study was to test dobutamine-stress echocardiography in a pediatric population to determine its feasibility, safety and reliability in the detection of graft coronary artery disease. METHODS: Eighteen patients, aged 2 days to 16.8 years at transplantation (mean 8.4 years), underwent 44 dobutamine-stress echocardiography (DSE) exams, at a follow-up of 1.1 to 11.8 years (mean 5.1 years). Selective coronary angiography was performed for comparison. Echocardiographic recordings were obtained in 4 standard views of the left ventricle and measurements carried out within the frames of a 16-segment model. Segmental scores of contractility were obtained for each segment and a total segmental contractility index was calculated at each stage. RESULTS: All patients reached the maximum dose stage. Maximum heart rate was 57% to 90% of predicted maximum. Maximum systolic blood pressure reached 190 mmHg. Segmental scores were normal in 37 and abnormal in 7 cases. Echographic results were concordant with angiography in 82% and discordant in 18% of the cases (4 negative DSEs with minor angiographic lesions, 2 positive DSEs with normal angiography), but there was no significant angiographic lesion with normal DSE. CONCLUSIONS: DSE is a safe and highly feasible non-invasive technique in transplanted children. A normal DSE study successfully predicts the absence of significant coronary artery disease in the post-transplant population.  相似文献   
84.
Abstract Traditional Native American people are experiencing serious health, economic, and social problems resulting from alcoholism. Native Americans maintain a worldview of health and illness that conflicts with the dominant culture's approach to treatment. The purposes of this study were to describe the health beliefs of traditional Muscogee (Creek) Indians concerning the causes of illness and learn how these beliefs relate to alcoholism. The researchers conducted in-depth interviews of 55 traditional Muscogee (Creek) participants to learn traditional beliefs about illness and alcoholism. Data were analyzed using content analysis. Results indicate that both illness and alcoholism are perceived as having natural and unnatural (supernatural) causes. A challenge facing nurses is how to provide culturally sensitive care when clients' and nurses' beliefs about the cause of alcoholism may be in conflict. The authors discuss preservation, accommodation, and repatterning of health care beliefs as a basis for planning culturally sensitive nursing care.  相似文献   
85.
A brief overview is provided of the bioactivity of macrolides against a range of bacterial species. Topics considered include the cellular pharmacokinetics of uptake and efflux of these drugs and the importance of intra- or extracellular and cytoplasmic or granular location on their activity. Emphasis is placed on the importance of synergy between macrolides and host defenses, with drug accumulation producing modification of cellular function, such as enhancement of phagocytosis, and exocytosis of polymorphonuclear neutrophils. Such interaction may explain the activity of such agents against organisms which normally inhibit fusion of phagolysosomes.  相似文献   
86.
OBJECTIVE: The authors describe their experience with left ventricular assist-device (LVAD) recipients undergoing noncardiac surgery and delineate surgical, anesthetic, and logistic factors important in the successful intraoperative management of these patients. SUMMARY BACKGROUND DATA: Left ventricular assist-devices have become part of the armamentarium in the treatment of end-stage heart failure. As the numbers of patients chronically supported with long-term implantable devices grows, general surgical problems that are commonly seen in other hospitalized patients are becoming manifest. Of particular interest is the intraoperative management of patients undergoing elective noncardiac surgical procedures. METHODS: The anesthesia records and clinical charts were reviewed for eight ventricular assist-device recipients undergoing general surgical procedures between August 1, 1990 and August 31, 1994. RESULTS: A total of 12 procedures were performed in 6 men and 2 women averaging 52.7 years of age. Mean time elapsed from device implantation to operation was 68 +/- 35 days. Conventional inhalational and intravenous anesthetic techniques were well tolerated in these patients undergoing diverse surgical procedures. No perioperative mortality was observed. Five of eight patients went on to successful cardiac transplantation. CONCLUSIONS: Hemodynamic recovery after LVAD insertion has defined a new group of patients who develop noncardiac surgical problems often seen in other critically ill patients. Recognition of the unique potential problems that the LVAD recipient may encounter in the perioperative period--in particular patient positioning, device limitations, and fluid and inotropic management--will ensure an optimal surgical outcome for LVAD recipients undergoing noncardiac surgery.  相似文献   
87.
Executive and compensatory memory retraining in traumatic brain injury   总被引:3,自引:0,他引:3  
A controlled treatment outcome study was conducted comparing the efficacy of memory remediation treatment with no treatment on traumatic brain-injury patients. The memory remediation treatment consisted of both compensatory and executive training skills and was delivered 6 hours weekly over a 2 1/2-week period. Six subjects in the treatment group and 6 subjects in the control group were matched on WAIS-R FSIQ scores, pre-test memory scores and age. Pre-and post-test measures were obtained for both groups on a paragraph memory task. A significant difference was demonstrated between the treatment and control post-test memory scores. The experimental group significantly improved memory scores beyond that of the control group, suggesting that memory remediation is effective for head-injury patients with memory deficits. Discussion of findings and suggestions for further investigation are presented.  相似文献   
88.
Ventricular vagal nerve endings are thought to trigger vasodepressor syncope. Reports of vasodepressor reactions associated with donor bradycardia after cardiac transplantation have led to speculation that vagal reinnervation occurs. We assessed reinnervation status in seven patients 23–36 months (median 24 months) post-transplantation. Heart rate responses to vagal manoeuvres (respiration, Valsalva) and sympathetic stimuli (exercise and injection of tyramine into the coronary artery supplying the sinus node) were measured. All patients underwent 60 min of 60° head-up tilt with foot plate support. During tilt four of the seven had vasodepressor reactions with a fall in mean arterial pressure of 20–90 mmHg. During vasodepression two patients had falls in donor heart rate of 13 and 40% relative to peak heart rate during tilt. These two patients had evidence of functional sympathetic reinnervation. By contrast the two patients without donor bradycardia during vasodepression had only limited or no evidence of sympathetic reinnervation. No patient had consistent evidence of parasympathetic reinnervation as judged by the heart rate response to vagal manoeuvres. Headup tilt can thus produce vasodepressor reactions with donor bradycardia after cardiac transplantation in the absence of consistent evidence of vagal reinnervation. Left ventricular nerve endings may not be the only mediators of tilt-induced vasodepressor reactions in man. Donor bradycardia during vasodepression may reflect sympathetic withdrawal and not vagal reinnervation.  相似文献   
89.
Factors influencing women to undergo screening mammography   总被引:2,自引:0,他引:2  
  相似文献   
90.
This paper reports on the views of patients with established heart disease of a structured programme of follow-up care provided by practice nurses (PNs) in general practice in England. It is based on in-depth interviews with 22 patients receiving an integrated primary and secondary care intervention being developed and piloted for patients following heart attack or diagnosis of angina. Patients identified the important features of follow-up care to be easy access to a health professional who possessed knowledge and social and emotional skills. A range of views about the ability of PNs to provide such care emerged from patients' accounts. patients' perceptions about the seriousness of their condition and the way PN follow-up care was provided in practices emerged as important issues affecting patients' views. In addition, perceptions about the practice nurse's role, status and knowledge, existing relationships with general practitioners, and issues of communication were also important factors. It is concluded that in order to develop high-quality PN-led services for patients with established heart disease, four issues need to be taken into account: practice nurse training; continuity of follow-up care; the integration of the primary and secondary care interface; and development of the practice nurse's status within the primary health care team.  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