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   4047篇
  免费   313篇
  国内免费   6篇
耳鼻咽喉   28篇
儿科学   94篇
妇产科学   92篇
基础医学   645篇
口腔科学   89篇
临床医学   450篇
内科学   736篇
皮肤病学   54篇
神经病学   354篇
特种医学   219篇
外科学   552篇
综合类   63篇
预防医学   427篇
眼科学   30篇
药学   303篇
中国医学   6篇
肿瘤学   224篇
  2021年   51篇
  2019年   57篇
  2018年   60篇
  2016年   42篇
  2015年   56篇
  2014年   64篇
  2013年   111篇
  2012年   126篇
  2011年   164篇
  2010年   79篇
  2009年   66篇
  2008年   142篇
  2007年   172篇
  2006年   169篇
  2005年   145篇
  2004年   140篇
  2003年   144篇
  2002年   150篇
  2001年   150篇
  2000年   154篇
  1999年   132篇
  1998年   55篇
  1997年   38篇
  1996年   43篇
  1995年   54篇
  1994年   40篇
  1993年   35篇
  1992年   115篇
  1991年   114篇
  1990年   115篇
  1989年   101篇
  1988年   109篇
  1987年   96篇
  1986年   100篇
  1985年   95篇
  1984年   72篇
  1983年   70篇
  1982年   50篇
  1981年   49篇
  1979年   45篇
  1978年   53篇
  1977年   40篇
  1976年   34篇
  1975年   38篇
  1974年   43篇
  1973年   38篇
  1972年   34篇
  1971年   39篇
  1970年   37篇
  1969年   36篇
排序方式: 共有4366条查询结果,搜索用时 15 毫秒
81.
When your thyroid gland is overactive, it produces too much thyroid hormone for your body. This is called hyperthyroidism, and it can cause a number of problems.  相似文献   
82.
Occiput-C1 and C1-C2 dissociations and dislocations have been well documented in the literature. However, after thorough review of the literature, we found very little in the literature regarding combined occiput-C1 and C1-C2 dissociations in adults who survived. We present 2 case reports describing the clinical presentation, initial management, operative treatment, and postoperative course of 2 patients who sustained traumatic combined occiput-C1 and C1-C2 dissociations. After initial stabilization, both patients underwent open reduction and posterior occipital-cervical fusion with segmental fixation. At recent follow-up, both patients maintain good sagittal alignment without loss of reduction, and they have radiographic progression to fusion, minimal pain, and improved neurologic function. Combined occiput-C1 and C1-C2 dissociations are rare but serious injuries. Incomplete dissociations may not be evident on initial radiographs. Computed tomography or magnetic resonance imaging is recommended for formal diagnosis. A traumatic dural tear may be present. We recommend open reduction and posterior occipital-cervical fusion with segmental fixation for these patients.  相似文献   
83.

Background  

Symptoms from poorly controlled gastroesophageal reflux disease (GERD) such as heartburn and regurgitation often resolve after laparoscopic Nissen fundoplication. Unfortunately, new gastrointestinal symptoms such as bloating may occur for some patients. Accurate data regarding the gastrointestinal symptoms experienced by patients who have had a laparoscopic fundoplication may help patients to make more informed decisions about pursuing surgery for their reflux disease.  相似文献   
84.
85.
Splash basins are used in arthroplasty cases to wash instruments. Several studies in the literature have shown these basins being a potential source of bacterial infection. This study assesses the risk of contamination of intraoperative splash basins used to wash and store instruments. A total of 46 random clean primary arthroplasty cases (32 hips, 13 knees, and 1 unicondylar knee) were studied by taking cultures of sterile splash basins as soon as they are opened (controls) and again at wound closure after instruments and debris have come into contact with the sterile water. All cultures were taken with sterile culture swabs and sent to the laboratory for aerobic, anaerobic, and fungal culture. Outcome measured was any positive culture. A total of 92 cultures from 46 cases were tested. Only 1 (2.17%) control culture, which grew Streptococcus viridans, was positive for bacterial growth. One of 46 samples (2.17%) taken at wound closure was positive for coagulase-negative Staphylococcus. Mean time between basin opening and wound closure was 180±45 minutes. For the 1 infected sample taken at the conclusion of the case, it was 240 minutes. Previous studies show contamination rates as high as 74% for splash basins used intraoperatively. Our study contradicts the belief that splash basins are a high source of infection, with only 2.17% of basins showing contamination. Splash basins can be a potential source of contamination, but the risk is not as high as previously cited in the orthopedic literature.  相似文献   
86.
87.
A segmented attenuation correction for PET   总被引:10,自引:0,他引:10  
A segmented attenuation correction technique has been developed for positron emission tomography which computes attenuation correction factors automatically from transmission images for use in the final image reconstruction. The technique segments the transmission image into anatomic regions by thresholding the histogram of the attenuation values corresponding to different regions such as soft tissue and lungs. Average values of attenuation are derived from these regions and new attenuation correction factors are computed by forward projection of these regions into sinograms for correction of emission images. The technique has been tested with phantom studies and with clinical cardiac studies in patients for 30- and 10-min attenuation scan times. This method for attenuation correction was linearly correlated (slope = 0.937 and r2 = 0.935) with the standard directly measured method, reducing noise in the final image, and reducing the attenuation scan time.  相似文献   
88.
Nicotine dependence is associated with increased risk for emotional, cognitive and neurological impairments later in life. This study investigated the long‐term effects of nicotine exposure during adolescence and adulthood on measures of depression, anxiety, learning and hippocampal pyramidal cell morphology. Mice (C57BL/6J) received saline or nicotine for 12 days via pumps implanted on postnatal day 32 (adolescent) or 54 (adults). Thirty days after cessation of nicotine/saline, mice were tested for learning using contextual fear conditioning, depression‐like behaviors using the forced swim test or anxiety‐like behaviors with the elevated plus maze. Brains from nicotine‐ or saline‐exposed mice were processed with Golgi stain for whole neuron reconstruction in the CA1 and CA3 regions of the hippocampus. Results demonstrate higher depression‐like responses in both adolescent and adult mice when tested during acute nicotine withdrawal. Heightened depression‐like behaviors persisted when tested after 30 days of nicotine abstinence in mice exposed as adolescents, but not adults. Adult, but not adolescent, exposure to nicotine resulted in increased open‐arm time when tested after 30 days of abstinence. Nicotine exposure during adolescence caused deficits in contextual fear learning indicated by lower levels of freezing to the context as compared with controls when tested 30 days later. In addition, reduced dendritic length and complexity in the apical CA1 branches in adult mice exposed to nicotine during adolescence were found. These results demonstrate that nicotine exposure and withdrawal can have long‐term effects on emotional and cognitive functioning, particularly when nicotine exposure occurs during the critical period of adolescence.  相似文献   
89.

Background  

Circumstances may arise during laparoscopic procedures in which alignment of the laparoscope and the instruments is off by 180°, creating a mirror image of the operative field. It has been shown that task performance is degraded under these reverse-alignment conditions, and that the magnitude of performance impairment is directly related to laparoscopic experience and skill. The aim of this study was to determine if reverse-alignment surgical skills could be developed through training.  相似文献   
90.
Wounds that exhibit delayed healing add extraordinary clinical, economic, and personal burdens to patients, as well as to increasing financial costs to health systems. New interventions designed to ease such burdens for patients with cancer, renal, or ophthalmologic conditions are often cleared for approval by the U.S. Food and Drug Administration (FDA) using multiple endpoints but the requirement of complete healing as a primary endpoint for wound products impedes FDA clearance of interventions that can provide other clinical or patient‐centered benefits for persons with wounds. A multidisciplinary group of wound experts undertook an initiative, in collaboration with the FDA, to identify and content validate supporting FDA criteria for qualifying wound endpoints relevant to clinical practice (CP) and patient‐centered outcomes (PCO) as primary outcomes in clinical trials. As part of the initiative, a research study was conducted involving 628 multidisciplinary expert wound clinicians and researchers from 4 different groups: the interdisciplinary core advisory team; attendees of the Spring 2015 Symposium on Advanced Wound Care (SAWC); clinicians employed by a national network of specialty clinics focused on comprehensive wound care; and Association for the Advancement of Wound Care (AAWC) and Wound Healing Society (WHS) members who had not previously completed the survey. The online survey assessed 28 literature‐based wound care endpoints for their relevance and importance to clinical practice and clinical research. Fifteen of the endpoints were evaluated for their relevance to improving quality of life. Twenty‐two endpoints had content validity indexes (CVI) ≥ 0.75, and 15 were selected as meriting potential inclusion as additional endpoints for FDA approval of future wound care interventions. This study represents an important first step in identifying and validating new measurable wound care endpoints for clinical research and practice and for regulatory evaluation.  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