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   4711篇
  免费   349篇
  国内免费   13篇
耳鼻咽喉   25篇
儿科学   120篇
妇产科学   40篇
基础医学   680篇
口腔科学   118篇
临床医学   415篇
内科学   917篇
皮肤病学   142篇
神经病学   890篇
特种医学   101篇
外国民族医学   2篇
外科学   615篇
综合类   19篇
一般理论   2篇
预防医学   319篇
眼科学   173篇
药学   240篇
肿瘤学   255篇
  2023年   29篇
  2022年   55篇
  2021年   128篇
  2020年   103篇
  2019年   93篇
  2018年   121篇
  2017年   99篇
  2016年   105篇
  2015年   143篇
  2014年   148篇
  2013年   221篇
  2012年   295篇
  2011年   369篇
  2010年   187篇
  2009年   171篇
  2008年   260篇
  2007年   300篇
  2006年   283篇
  2005年   312篇
  2004年   236篇
  2003年   218篇
  2002年   224篇
  2001年   92篇
  2000年   99篇
  1999年   92篇
  1998年   49篇
  1997年   38篇
  1996年   40篇
  1995年   34篇
  1994年   23篇
  1993年   15篇
  1992年   42篇
  1991年   37篇
  1990年   32篇
  1989年   26篇
  1988年   27篇
  1987年   15篇
  1986年   24篇
  1985年   21篇
  1984年   15篇
  1983年   13篇
  1982年   14篇
  1980年   11篇
  1979年   12篇
  1973年   17篇
  1972年   11篇
  1971年   20篇
  1969年   15篇
  1968年   10篇
  1967年   10篇
排序方式: 共有5073条查询结果,搜索用时 13 毫秒
91.
PURPOSE/OBJECTIVES: To determine the effects of virtual reality (VR) glasses on adolescents with cancer undergoing lumbar punctures (LPs). DESIGN: Pilot study using an experimental, control group design. SETTING: In-hospital oncology clinic. SAMPLE: 30 adolescents with cancer (17 in the VR and 13 in the control group) undergoing frequent LPs. METHODS: Subjects were randomly assigned to groups. Both groups received standard intervention during the LP, but the experimental group also wore VR glasses and watched a video. Following the LP, both groups rated their pain using a visual analog scale (VAS) and were interviewed to evaluate their experience. MAIN RESEARCH VARIABLES: Pain, subjective evaluation of experience. FINDINGS: Although VAS pain scores were not statistically different between the two groups (p = 0.77), VAS scores tended to be lower in the VR group (median VAS of 7.0, range 0-48) than in the control group (median VAS of 9.0, range 0-59). 77% of subjects in the experimental group said the VR glasses helped to distract them from the LP. CONCLUSIONS: VR glasses are a feasible, age-appropriate, nonpharmacologic adjunct to conventional care in managing the pain associated with LPs in adolescents. IMPLICATIONS FOR PRACTICE: The clinical application of various age-appropriate distracters to reduce pain in adolescents undergoing painful procedures should be explored.  相似文献   
92.
Gastrointestinal motility disorders are a commonly encountered problem. Although some are associated with organic alterations, others are defined by their symptoms, and no anatomic or histologic organic changes are to be found. In most cases, the etiology is completely unclear. Endoscopy, with the option of obtaining biopsies for histopathologic evaluation, plays the most important role in the diagnostic workup, as it can exclude such lesions as tumors, ulcers, inflammatory processes, and diverticula and it helps to define the grade and extent of motility-associated diseases (e.g., GERD). Furthermore, endoscopic interventional procedures offer sufficient treatment of several motility-related disorders (e.g., achalasia, GERD, its associated diseases, secondary constipation).  相似文献   
93.
OBJECTIVE: To evaluate the prognostic impact of early pathologic sympathetic activation after stroke. METHODS: The authors examined 112 consecutive patients (mean age, 69 years; 60 men) with their first brain infarction. A pathologic sympathetic activation was presumed if the initial norepinephrine level exceeds 300 pg/mL. In addition, involvement of the insular cortex, nighttime blood pressure changes, and several cardiovascular risk factors were determined. One-year outcome measures were mortality rate, cardiovascular and cerebrovascular events, and activities of daily living (Barthel index and Rankin score). RESULTS: Norepinephrine levels greater than 300 pg/mL, nighttime blood pressure increases, and insular involvement were associated with a lower Barthel index (p < 0.005) at the 1-year follow-up. By stepwise logistic regression analysis, insular infarction, serum norepinephrine concentration, right-sided infarction, and nighttime blood pressure increase were significant and independent predictors of an unfavorable functional outcome. Cox regression analysis showed a higher rate of cardiovascular and cerebrovascular events (hazard ratio, 2.9; 95% CI, 1.07; 6.83; p < 0.04) in patients with initially increased norepinephrine concentrations. CONCLUSIONS: The involvement of the insular cortex, the occurrence of a pathologic nighttime blood pressure increase, and an initially increased serum norepinephrine concentration are independent predictors of poor long-term outcome.  相似文献   
94.
95.
96.
OBJECTIVE: To determine the effect of large doses of vitamin C in the treatment of the common cold. STUDY DESIGN: Double-blind, randomised clinical trial with four intervention arms: vitamin C at daily doses of 0.03g ("placebo"), 1 g, 3g, or 3g with additives ("Bio-C") taken at onset of a cold and for the following two days. PARTICIPANTS AND SETTING: 400 healthy volunteers were recruited from staff and students of the Australian National University, Canberra, ACT, between May 1998 and November 1999. The trial continued for 18 months. INTERVENTIONS: Participants were instructed to commence medication when they had experienced early symptoms of a cold for four hours, and to record daily their symptoms, severity, doctor visits and use of other medications. MAIN OUTCOME MEASURES: Duration of symptoms and cold episodes; cumulative symptom severity scores after 7, 14 and 28 days; doctor visits; and whether participants guessed which medication they were taking. RESULTS: 149 participants returned records for 184 cold episodes. No significant differences were observed in any measure of cold duration or severity between the four medication groups. Although differences were not significant, the placebo group had the shortest duration of nasal, systemic and overall symptoms, and the lowest mean severity score at 14 days, and the second lowest at 7 and 28 days. CONCLUSIONS: Doses of vitamin C in excess of 1 g daily taken shortly after onset of a cold did not reduce the duration or severity of cold symptoms in healthy adult volunteers when compared with a vitamin C dose less than the minimum recommended daily intake.  相似文献   
97.
This study explores further the reasons given by the first year medical students in comparison with first year business and first year psychology students for their selection of lectures, student role play, and student presentations as their least preferred teaching method. The reasons were originally given in a questionnaire exploring student expectations of university teaching completed by 195 medical, 128 business and 72 psychology students in their first week at university (Sander et al, 2000). The analysis reported here suggests that whilst students irrespective of course gave similar reasons for not liking lectures, there were subtle differences between medical students and business and psychology students in the reasons they gave for not liking student role play and student presentations. These differences suggest that many first year medical students can be suspicious of the value of student centred learning methods. Teachers hoping to use these methods should acknowledge student suspicion and work to help students see the value of these techniques to encourage their full participation.  相似文献   
98.
Pregnant Sprague-Dawley rats received a single oral dose of 0, 20, 60, or 180 ng/kg 2,3,7,8-tetrachlorodibenzo-p-dioxin on day 8 of gestation. Each litter contributed a single male-female pair trained to press a lever to obtain food pellets under two operant behavior procedures. Initially, each lever press was reinforced. The fixed-ratio (FR) requirement was then increased every four sessions from the initial setting of 1 to values between 6 and 71. We then studied responses for 30 days under a multiple schedule combining FR 11 and another schedule requiring a pause of at least 10 sec between responses (DRL 10-sec). TCDD evoked a sexually dimorphic response pattern. Generally, TCDD-exposed males responded at lower rates than control males. In contrast, exposed females responded at higher rates than controls. Each response measure from the mult-FR DRL schedule yielded a male-female difference score. We used the differences in response rate to calculate benchmark doses based on the relative displacement from modeled zero-dose performance of the effective dose at 1% (ED(01)) and 10% (ED(10)), as determined by a second-order polynomial fit to the dose-effect function. For the male-female difference in FR rate of responding, the mean ED(10) was 2.77 ng/kg with a 95% lower bound of 1.81 ng/kg. The corresponding ED(01) was 0.27 ng/kg with a 95% lower bound of 0.18 ng/kg. For the male-female difference in DRL rate, the mean ED(10) was 2.97 ng/kg with a 95% lower bound of 2.02 ng/kg. The corresponding ED(01) was 0.30 ng/kg with a 95% lower bound of 0.20 ng/kg. These values fall close to, but below, current estimates of human body burdens of 13 ng/kg, based on TCDD toxic equivalents.  相似文献   
99.
To investigate the relevance of intraoperative macroscopic evaluation of adnexal masses a prospective study was conducted from June 1st, 1993 to May 31st, 1994, which included 57 premenopausal and 60 postmenopausal women, who underwent laparotomy because of a cystic adnexal mass. The surgeons were asked to classify the tumor intraoperatively as benign or malignant and to assign to histologic groups. In addition cytology of the cyst fluid and a biopsy from the cystic wall were evaluated. Comparison of these items with the results of permanent section diagnosis revealed the tendency of the surgeons to underestimate adnexal masses depending on patients' age and the complexity of the tumor, despite of the knowledge of preoperative ultrasonographic findings. Sufficient cytolologic examination was possible in only one third of aspirates and only 21% of the examined postmenopausal malignant neoplasms have correctly been diagnosed by cytology. Evaluation of the biopsy specimens demonstrates a marked percentage of false negatives with respect to benign tumors (30% of non-functional benign neoplasms in the premenopause were assessed as functional cysts) as well as malignant neoplasms (only 72% were diagnosed correctly in the postmenopause group). In conclusion intraoperative subjective assessment, cytology and representative biopsies do not necessarily concur with the definitive histological diagnosis.  相似文献   
100.
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