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   8121篇
  免费   744篇
  国内免费   25篇
耳鼻咽喉   108篇
儿科学   232篇
妇产科学   257篇
基础医学   1053篇
口腔科学   159篇
临床医学   681篇
内科学   1925篇
皮肤病学   114篇
神经病学   625篇
特种医学   271篇
外科学   1177篇
综合类   77篇
一般理论   3篇
预防医学   781篇
眼科学   132篇
药学   616篇
中国医学   22篇
肿瘤学   657篇
  2023年   59篇
  2022年   105篇
  2021年   237篇
  2020年   126篇
  2019年   186篇
  2018年   251篇
  2017年   172篇
  2016年   196篇
  2015年   220篇
  2014年   297篇
  2013年   393篇
  2012年   549篇
  2011年   586篇
  2010年   300篇
  2009年   276篇
  2008年   476篇
  2007年   488篇
  2006年   464篇
  2005年   453篇
  2004年   430篇
  2003年   394篇
  2002年   355篇
  2001年   183篇
  2000年   195篇
  1999年   142篇
  1998年   71篇
  1997年   44篇
  1996年   53篇
  1995年   62篇
  1994年   44篇
  1993年   46篇
  1992年   85篇
  1991年   55篇
  1990年   77篇
  1989年   65篇
  1988年   53篇
  1987年   72篇
  1986年   74篇
  1985年   54篇
  1984年   58篇
  1983年   36篇
  1982年   40篇
  1981年   42篇
  1980年   29篇
  1979年   36篇
  1978年   33篇
  1977年   20篇
  1975年   20篇
  1973年   21篇
  1972年   19篇
排序方式: 共有8890条查询结果,搜索用时 15 毫秒
21.
22.
The aetiology of porphyria cutanea tarda (PCT) has not been elucidated, but the possibility of an autoimmune mechanism has been proposed. We report a case of an unknown clinical combination of PCT with autoimmune hypothyroidism, alopecia universalis and vitiligo with thyroid and parietal cell circulating antibodies. This is highly suggestive of underlying autoimmune damage in this patient.  相似文献   
23.
Acute effects of cypermethrin, a pesticide used to treat ectoparasite infestations of salmon, were assessed using the calanoid copepod Acartia tonsa. A. tonsa has been widely used for hazard assessment of chemicals in the marine environment using acute toxicity tests, but only with randomly selected adults, assuming a sex ratio of 1:1. The present study assesses the environmental hazard of cypermethrin by exposing nauplii and adult males and females, separately. Our results showed that the naupliar stages were 28 times more sensitive to cypermethrin than adults after 96 h of exposure, with LC50s of 0.005 μg L−1 and 0.142 μg L−1, respectively. Significant differences in sensitivity between sexes were only found during the first 24 h of exposure, with males being approximately twice as sensitive as females. The results of age-related variation in sensitivity are supported by studies with other species of copepods and toxicants, where the increased capacity of the adults for detoxification, the allometric differences in weight and size, and the molting process are given as explanations. Variation in sensitivity between sexes is discussed in terms of faster depuration rates in females through egg production and implications of feeding rate changes after 24 h of exposure. Our results suggested that standard toxicity test methods using A. tonsa are unsatisfactory because the most sensitive life stage is not included and sex-related differences in tolerance are not taken into account. We also found that cypermethrin caused significant mortality in Acartia at exposures concentrations from one to three orders of magnitudes lower than the recommended field treatment concentration for copepodic infestations. Received: 27 April 2001/Accepted: 1 July 2001  相似文献   
24.
Alcohol consumption by pregnant women and birth outcome were studied in 9953 livebirths, 3309 fetal deaths and 5332 infant deaths from the 1988 National Maternal and Infant Health Survey. In crude analyses, race, age, mother's education, prenatal care, parity, low birthweight, gestational age, smoking and alcohol consumption during pregnancy were significantly related to the occurrence of fetal deaths and infant deaths. Among women having livebirths, race, age, mother's education, prenatal care, prematurity, gestational age, smoking and alcohol consumption during pregnancy were significantly related to having a low birthweight baby (< 2500 g). In this group, women who drank more during pregnancy also smoked more, were younger and less educated than women who drank at lower levels or not at all. The relationship of alcohol consumption during pregnancy and infant birthweight for those women having livebirths was studied using multivariable linear regression. The results indicated that race, mother's education, baby's sex, parity, mother's height, mother's body mass index and smoking, but not alcohol consumption, were significantly related to birthweight. Multivariable logistic regressions were performed for the occurrence of low birthweight, fetal death and infant death. The effect of alcohol was significant in all these analyses. These results indicate that alcohol has an important relationship with birth outcome, but that for the drinking reported in this study, the alcohol effect on mean birthweight is small relative to that of other risk factors, accounting for the non-significant result in the multiple linear regression.  相似文献   
25.
We study 40 patients, 55 +/- 7 years old with acute myocardial infarction treated early by thrombolytic therapy (20 STK and 20 rt-PA). All patients were angiographically studied in the following conditions: 1) baseline, before initiating therapy. 2) Three hours after treatment. 3) Twenty four hours later. 4) Before discharge. The infarct related artery was patent 24 hours after treatment in 31 patients (78%); five of them were patent before treatment, and we observed an early reperfusion in 20 patients (57%) and late reperfusion in 6 patients (17%). The number of patients with angiographic evidence of intraluminal thrombus decreased progressively through conditions while the grade TIMI of coronary perfusion increased in the absence of reocclusion. Final regional wall motion of infarct related myocardial zones and their degree of recovery were significantly higher in recanalized patients, as compared with non-reperfused patients. Similarly, left ventricular functional recovery was higher in patients with antegrade of collateral flow to the infarct area, as compared with totally occluded patients.  相似文献   
26.
27.
Commonly used neuropsychological tests were administered to 91 detoxified alcoholics at the beginning of treatment. Statistically significant relationships were observed between test scores and post treatment consumption determined 8 months after completing treatment for 72 patients. The results varied depending upon the particular measure of posttreatment consumption evaluated and the type of statistical analysis used. The most consistent relationships were often counter to the notion that increased neuropsychological performance is correlated with a more favorable treatment outcome. Neuropsychological evaluation is of limited clinical utility in predicting posttreatment alcohol consumption.  相似文献   
28.
Increasing numbers of patients are undergoing diagnostic catheterization as outpatients; however, a small proportion of patients requires hospital admission following the procedure. Unplanned admissions after consecutive outpatient cardiac catheterizations performed during 1 year were prospectively reviewed to determine the incidence of and reasons for admission. Among 847 patients undergoing outpatient cardiac catheterization, 130 patients (15%) required hospital admission after the procedure. Admitted patients were divided into four groups: patients undergoing immediate percutaneous transluminal coronary angioplasty (PTCA) (Group 1; 33%), patients with severe cardiac disease requiring urgent intervention (Group 2; 48%), patients suffering complications or hemodynamic instability (Group 3; 15%), and patients whose procedures were completed too late to allow same-day discharge (Group 4; 4%). Patients over 65 were more likely to require admission and women were more likely to be admitted with complications or hemodynamic instability. Findings are compared with results of other outpatient series, and implications regarding appropriate setting for outpatient catheterization are discussed.  相似文献   
29.
30.
Primary linitis plastica of the rectum is an infrequent and unusual rectal carcinoma. We report a new case that presented clinically as a haemorrhoidal syndrome. We comment on the characteristics--clinical picture and histopathology--of this uncommon presentation of rectal tumour, as well as its clinical history and prognosis taking into account that the literature consulted indicated the unusualness of primary linitis plastica of the rectum.  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