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   40408篇
  免费   3311篇
  国内免费   84篇
耳鼻咽喉   634篇
儿科学   1230篇
妇产科学   856篇
基础医学   5725篇
口腔科学   560篇
临床医学   4905篇
内科学   7459篇
皮肤病学   791篇
神经病学   4118篇
特种医学   1327篇
外科学   5524篇
综合类   493篇
一般理论   43篇
预防医学   3974篇
眼科学   740篇
药学   2521篇
中国医学   46篇
肿瘤学   2857篇
  2023年   448篇
  2022年   781篇
  2021年   1697篇
  2020年   1027篇
  2019年   1516篇
  2018年   1650篇
  2017年   1153篇
  2016年   1214篇
  2015年   1320篇
  2014年   1754篇
  2013年   2555篇
  2012年   3272篇
  2011年   3161篇
  2010年   1585篇
  2009年   1399篇
  2008年   2313篇
  2007年   2282篇
  2006年   2028篇
  2005年   1866篇
  2004年   1802篇
  2003年   1473篇
  2002年   1315篇
  2001年   477篇
  2000年   468篇
  1999年   421篇
  1998年   275篇
  1997年   228篇
  1996年   177篇
  1995年   153篇
  1994年   141篇
  1993年   133篇
  1992年   285篇
  1991年   240篇
  1990年   240篇
  1989年   245篇
  1988年   237篇
  1987年   218篇
  1986年   267篇
  1985年   180篇
  1984年   166篇
  1983年   140篇
  1982年   113篇
  1981年   103篇
  1980年   103篇
  1979年   165篇
  1978年   100篇
  1976年   79篇
  1975年   79篇
  1973年   74篇
  1971年   77篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
OBJECTIVE: Inpatients with major depressive illness often have coexistent nonaffective psychiatric and/or medical conditions. The authors' objective is to address the following questions: 1) What is the effect of comorbid illness on the severity of major depression and associated psychosocial factors? 2) How does the course of depression differ for patients with and without concurrent illness? 3) Do patients with compound depression differ in rate of recovery and time to recovery from patients with pure depression? METHOD: The subjects were 78 patients with a DSM-III diagnosis of major depression who were consecutively admitted to an acute care university-affiliated psychiatric hospital; 37 of these patients had major depression only and 41 had major depression compounded by a coexisting axis I, II, or III condition. The patients were studied while hospitalized and for 12 months after hospital discharge. Instruments used included the Modified Hamilton Rating Scale for Depression, the Global Assessment Scale, and the Social Readjustment Rating Scale. RESULTS: Patients with compound depression reported significantly poorer functioning over the 12-month follow-up period and had lower recovery rates than the patients with pure depression. There were no differences in recovery rates between men and women with compound depression, but significantly more men than women with pure depression recovered. CONCLUSIONS: Compound depression is a common clinical occurrence, the course of illness is more difficult for patients with compound depression than for patients with pure depression, and the recovery rate of patients with compound depression is lower than that of patients with pure depression.  相似文献   
62.
Performance standards for toric soft contact lenses.   总被引:1,自引:0,他引:1  
PURPOSE: To simplify the clinical assessment of toric soft contact lens (TSCL) on-eye behavior by establishing a set of standard clinical evaluation techniques. The likely performance range expected among the TSCL wearing population was determined for a series of lens designs and acceptable performance standards indicated for each variable. METHODS: Four prism-ballast, two peri-ballast and one dynamic stabilization TSCL designs were each worn by groups of 20 subjects in a nondispensing study. After 20 min of lens wear, lenses were assessed, in right eyes only, for subjective comfort (100-point scale), lens mislocation (degrees deviation from vertical) and rotational recovery after deliberate 30 degrees mislocation (degrees/10 blinks). The percentage of lenses orienting within +/-10 degrees of target orientation (zero rotation) and the variability of orientation (standard deviation of mislocation) were also calculated for each lens group. RESULTS: Based on partitioning of the data distributions for each variable, performance was designated as excellent, acceptable or poor. Corresponding performance cut-offs were determined at > or =90, 89 to 80, and <80 for subjective comfort, < or =+/-6 degrees , +/-7 degrees to 10 degrees , and >+/-10 degrees for mislocation, >10 degrees /10 blinks, 10 degrees to 6 degrees /10 blinks, and <6 degrees /10 blinks for rotational recovery. For groups of wearers the appropriate cut-offs were > or =90%, 89 to 70%, and <70% of lenses orienting within +/-10 degrees of target orientation and <+/-6 degrees , +/-6 degrees to 10 degrees , and >+/-10 degrees for variability of orientation. CONCLUSION: Techniques suitable for the evaluation of TSCL clinical performance have been described and guidelines for the assessment of such lenses established. In the process, we have identified potential performance differences that may relate to variations in TSCL design.  相似文献   
63.
Intracranial injuries resulting from boxing: a review (1918-1985)   总被引:2,自引:0,他引:2  
A review of the available records indicates that there have been a substantial number of fatalities in boxers due to intracranial injuries sustained in the ring in comparison to the numbers engaged at both amateur and professional levels. The number of such fatalities has decreased steadily in recent years owing to different measures taken by boxing authorities to decrease the physical hazards in the ring and to improve monitoring of boxers during bouts by referees and physicians. The considerable concern about the long-term effects of repeated brain injury as the result of boxing in producing chronic encephalopathy is adequately justified by the many studies of live boxers and pathologic examinations of brains of former boxers made and recorded over the years since 1952. These indicate clearly a significant relationship between the numbers of bouts fought and the presence of severity of chronic encephalopathy. Because it is unlikely that currently adopted protective measures will substantially reduce these hazards, even though they have apparently reduced direct fatalities, a reasonable approach to prevention would be to reduce the number and severity of blows to the head. This might be done by making any blow to the head in boxing a foul and a reason for disqualification. Another approach would be the elimination of boxing.  相似文献   
64.
65.
Poverty influences health status, life expectancy, health behaviours, and use of health services. This study examined factors influencing the use of health-related services by people living in poverty. In the first phase, 199 impoverished users of health-related services in 2 large Canadian cities were interviewed by their peers. In the second phase, group interviews with people living in poverty (n = 52) were conducted. Data were analyzed using thematic content analysis. Diverse health-related services were used to meet basic and health needs, to maintain human contact, and to cope with life's challenges. Use of services depended on proximity, affordability, convenience, information, and providers' attitudes and behaviours. Use was impeded by inequities based on income status. To promote the health of people living in poverty, nurses and other health professionals can enhance the accessibility and quality of services, improve their interactions with people living in poverty, provide information about available programs, offer coordinated community-based services, collaborate with other sectors, and advocate for more equitable services and policies.  相似文献   
66.
Digital nerve injuries in the hand are common and can result in significant impairment and functional restriction. Despite this, there is relatively little literature, particularly with respect to postoperative rehabilitation. Splinting after repair, purported to protect the repaired nerve from excessive stretch is still commonly used. Recent cadaveric studies indicate postoperative rehabilitation is not necessary with resection up to 2.5mm. A randomized controlled trial was therefore undertaken to determine whether splinting after isolated 5th degree digital nerve transection is in fact necessary. Twenty-six subjects were recruited over a two-year period and randomized to either three weeks of hand-based splinting or free active motion. ANCOVA indicated no differences in sensibility at six months between the two groups. Subjects also reported their greatest functional limitations were because of hyperesthesia. Although this study is underpowered, these limited results suggest splinting may not be required postoperatively.  相似文献   
67.
A closed femur fracture pain model was developed in the C57BL/6J mouse. One day after fracture, a monoclonal antibody raised against nerve growth factor (anti-NGF) was delivered intraperitoneally and resulted in a reduction in fracture pain-related behaviors of approximately 50%. Anti-NGF therapy did not interfere with bone healing as assessed by mechanical testing and histomorphometric analysis. INTRODUCTION: Current therapies to treat skeletal fracture pain are limited. This is because of the side effect profile of available analgesics and the scarcity of animal models that can be used to understand the mechanisms that drive this pain. Whereas previous studies have shown that mineralized bone, marrow, and periosteum are innervated by sensory and sympathetic fibers, it is not understood how skeletal pain is generated and maintained even in common conditions such as osteoarthritis, low back pain, or fracture. MATERIALS AND METHODS: In this study, we characterized the pain-related behaviors after a closed femur fracture in the C57BL/6J mouse. Additionally, we assessed the effect of a monoclonal antibody that binds to and sequesters nerve growth factor (anti-NGF) on pain-related behaviors and bone healing (mechanical properties and histomorphometric analysis) after fracture. RESULTS: Administration of anti-NGF therapy (10 mg/kg, days 1, 6, and 11 after fracture) resulted in a reduction of fracture pain-related behaviors of approximately 50%. Attenuation of fracture pain was evident as early as 24 h after the initial dosing and remained efficacious throughout the course of fracture pain. Anti-NGF therapy did not modify biomechanical properties of the femur or histomorphometric indices of bone healing. CONCLUSIONS: These findings suggest that therapies that target NGF or its cognate receptor(s) may be effective in attenuating nonmalignant fracture pain without interfering with bone healing.  相似文献   
68.
PURPOSE: The Esophageal-Tracheal Combitube (Combitube) is widely used for the management of the airway during cardiopulmonary resuscitation in the pre-hospital setting. Although serious complications have been reported with the Combitube, there is a paucity of data relative to the frequency and nature of such complications. The objective of this retrospective study was to determine the incidence and the nature of complications associated to the Combitube in the pre-hospital setting. METHODS: Since 1993, in the Quebec City Health Region, the basic life support treatment algorithm for emergency medical technicians has included the use of a Combitube as the primary airway device for management of all patients presenting with cardiac or respiratory arrest. The database of the emergency coordination services was searched for the period between 1993 and 2003 (2,981 patients). Only those patients who survived at least 12 hr were included. Medical records of these patients were reviewed to identify complications related to the use of the Combitube. RESULTS: Two-hundred-eighty (280) patients were identified. Fifty-eight (58) patients (20.7%, confidence interval (CI)95%=16.0%-25.4%) presented 69 complications: aspiration pneumonitis (n=31), pulmonary aspiration (n=16), pneumothorax (n=6), upper airway bleeding (n=4), esophageal laceration (n=3), sc emphysema (n=2), esophageal perforation and mediastinitis (n=2), tongue edema (n=2), vocal cord injury (n=1), tracheal injury (n=1), and pneumomediastinum (n=1). Thirteen of these complications (12 patients, 4.3%, CI95%=2.0%-6.3%) were judged as most likely resulting from trauma associated with insertion of the Combitube. CONCLUSION: The use of the Combitube in the pre-hospital setting is associated with a notable incidence of serious complications.  相似文献   
69.
70.

Background  

Glioblastoma multiforme is the most malignant form of brain tumor. Despite treatment including surgical resection, adjuvant chemotherapy, and radiation, these tumors typically recur. The recurrent tumor is often resistant to further therapy with the same agent, suggesting that the surviving cells that repopulate the tumor mass have an intrinsic genetic advantage. We previously demonstrated that cells selected for resistance to 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) are near-diploid, with over-representation of part or all of chromosomes 7 and 22. While cells from untreated gliomas often have over-representation of chromosome 7, chromosome 22 is typically under-represented.  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