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   48410篇
  免费   3742篇
  国内免费   164篇
耳鼻咽喉   687篇
儿科学   1331篇
妇产科学   846篇
基础医学   6397篇
口腔科学   676篇
临床医学   5092篇
内科学   10148篇
皮肤病学   538篇
神经病学   4650篇
特种医学   1796篇
外科学   7881篇
综合类   978篇
现状与发展   1篇
一般理论   41篇
预防医学   3879篇
眼科学   658篇
药学   3339篇
中国医学   60篇
肿瘤学   3318篇
  2023年   258篇
  2022年   535篇
  2021年   1264篇
  2020年   711篇
  2019年   1145篇
  2018年   1383篇
  2017年   926篇
  2016年   1072篇
  2015年   1285篇
  2014年   1699篇
  2013年   2264篇
  2012年   3754篇
  2011年   3779篇
  2010年   2107篇
  2009年   1886篇
  2008年   3171篇
  2007年   3255篇
  2006年   3153篇
  2005年   3208篇
  2004年   2860篇
  2003年   2710篇
  2002年   2463篇
  2001年   491篇
  2000年   375篇
  1999年   470篇
  1998年   519篇
  1997年   449篇
  1996年   386篇
  1995年   368篇
  1994年   319篇
  1993年   293篇
  1992年   289篇
  1991年   261篇
  1990年   245篇
  1989年   226篇
  1988年   220篇
  1987年   179篇
  1986年   179篇
  1985年   158篇
  1984年   177篇
  1983年   144篇
  1982年   165篇
  1981年   165篇
  1980年   131篇
  1979年   110篇
  1978年   99篇
  1977年   89篇
  1976年   81篇
  1973年   77篇
  1971年   66篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
71.
One hundred insulin-dependent diabetic patients (age < 45 years, 53 smokers) were followed for six years. The age, duration of diabetes and mean glycated haemoglobin levels, were comparable between the smokers and non-smokers. Microvascular complications (retinopathy and increased urine albumin excretion) were commoner and more severe in the smoking group at six years, particularly in heavy smokers. Of the 45 original smokers reviewed at six years, 12 (27%) had stopped, six of whom had developed microvascular complications. Only two of the ''heavy'' initial smokers, likely to be at most risk, had stopped smoking, and three original non-smokers had started smoking.  相似文献   
72.
73.
OBJECTIVE: Our purpose was to determine whether the incidence of postoperative endometritis and wound infection is associated with the method of placental removal at the time of cesarean section.STUDY DESIGN: Parturients undergoing cesarean delivery were prospectively randomized to have the placenta removed manually or spontaneously. Patients were excluded from participation if they had received intrapartum prophylactic antibiotics or had been determined to have chorioamnionitis. After delivery of the infant women in the manual group had the placenta extracted by the primary surgeon, whereas women in the spontaneous group had the placenta delivered by gentle traction on the umbilical cord. All study subjects received perioperative prophylactic antibiotics. The primary outcome variable was a postcesarean infection, defined as postcesarean endometritis or wound cellulitis requiring drainage and antibiotic therapy.RESULTS: A total of 333 women were enrolled in the investigation, with 165 assigned to the manual removal group and 168 allocated to have spontaneous removal. There were no statistically significant differences in mean gestational age, frequency or duration of ruptured membranes, frequency or duration of labor, or mean number of vaginal examinations between the two study groups. Postoperative infections occurred in 25 of 168 (15%) women in the spontaneous delivery group compared with 44 of 165 (27%) women in which the placenta was manually extracted (relative risk 0.6, 95% confidence interval 0.4 to 0.9, p = 0.01). Subset analysis of patients delivered with ruptured membranes similarly demonstrated a statistically significant reduction in the incidence of postoperative infections with spontaneous placental removal compared with manual extraction (20% vs. 38%, relative risk 0.5, 95% confidence interval 0.3 to 0.9, p = 0.02). There was a similar trend toward a reduction in postdelivery infections associated with spontaneous placental removal in women with intact membranes; however, this difference did not attain statistical significance.CONCLUSIONS: Spontaneous delivery of the placenta after cesarean delivery is associated with a decrease in the incidence of postcesarean infections. (Am J Obstet Gynecol 1997;176:1250-4.)  相似文献   
74.
This study compared one dose of cefotetan with three doses of piperacillin as prophylaxis against wound infection in 153 patients undergoing elective colorectal surgery. The patients were randomized into two groups: the first received 2 g cefotetan intravenously with induction of anaesthesia (n = 75), and the second received three doses of 2 g piperacillin (n = 78). Wound infection was defined as the presence of an abscess or discharging pus from the wound. In the cefotetan group there were 14 (19%) wound infections and 13 (17%) in the piperacillin group. There were three septic deaths, one in the cefotetan group and two in the piperacillin group. Both groups were comparable with regard to age, sex, nature of pathology and pre- and perioperative risk factors. No significant haematological or biochemical abnormalities were detected. The only adverse reaction was one patient who had an allergic reaction (rash) to piperacillin. These data suggest that single-dose cefotetan is as effective as triple-dose piperacillin in prophylaxis against infection in elective colorectal surgery.  相似文献   
75.
We present a case in which an open fracture of the ulna penetrated the skull and caused a comminuted, depressed skull fracture with a large intraparenchymal hematoma containing bone fragments.  相似文献   
76.
Emphasis on the social service needs of the deaf and hearing impaired has increased in the past decade. The literature that resulted from this attention is fragmented, however, and does not always offer the structure and direction that is needed. This review of the literature identifies issues related to effective service delivery with the objective of enhancing practitioners' understanding and awareness of the social service needs of the deaf community. A second objective is to stimulate interest and action in service delivery, program development, and direct service for the deaf.  相似文献   
77.
This study investigated the effects of structured group workshops for a population with special needs. Twenty subjects, each with a mild or moderate mental handicap, attended a series of 10 weekly 1-hour music workshops on the structured group playing of a Javanese Gamelan. Twenty subjects formed a non-intervention control group. The experimental hypothesis was that participation in the experimental group would produce significant improvements in musical ability as measured by the Rossi test of musical ability, devised and validated for use in this study. Significant gains in communication skills as measured by the Communication Assessment Profile for Adults with a Mental Handicap (CASP) and self-esteem levels measured by the Khalid semantic differential technique were also postulated. It was also suggested that these gains would be significantly correlated. Results show significant gains in musical ability (instrumental rhythm production: t = 5.67, d.f. = 29, p < 0.01 and simple rhythm production: t = 8.42, d.f. = 29, p < 0.01) and communication skills (t = 4.69, d.f. = 29, p < 0.01). Moreover these results are significantly correlated (r = 0.59, p < 0.05, r = 0.75, p < 0.05, r = 0.56, p < 0.05). A ceiling effect was obtained in the measurement of self-esteem. It is suggested that these gains derive from certain aspects of the musical communicative environment at the workshops. Suggestions for future research involve examining the possible influences on these developments.  相似文献   
78.
An easy-to-calculate approximation to the Shapiro—Francia W' test and its P-value is proposed. Its accuracy is sufficient for practical application in samples of size 5 or larger.  相似文献   
79.
The discriminative stimulus properties of (+)-lysergic acid diethylamide (LSD) and lisuride hydrogen maleate (LHM), were compared in a three-choice, water reinforced (FR 20) situation in which rats were required to press one lever following LSD (0.08 mg/kg), a second lever following LHM (0.04 mg/kg), and a third lever following saline. Reliable drug-appropriate responding was established in 72 sessions. Dose-response tests with LSD and LHM indicated that, as dose increased, the per cent of responding on the lever associated with the particular training drug also increased; little or no cross-transfer occurred between LSD and LHM. In generalization tests, the serotonin (5-HT) agonist quipazine substituted for LSD but not LHM while the dopamine (DA) agonist apomorphine mimicked LHM but not LSD; an unrelated compound, pentylenetetrazol (PTZ), produced responding on the saline-appropriate lever. In combination tests, 5-HT antagonists (e.g., BC-105 and low doses of pirenperone) blocked responding on the LSD lever while DA antagonists (e.g., haloperidol and much higher doses of pirenperone) blocked LHM-appropriate responding. These data suggest that the three-lever (D-D-N) procedure is similar to, but can be more sensitive than the two-lever (D-N) procedure (because it can differentiate between LSD and LHM); they therefore at least partially support the hypothesis that three-choice discriminations can be conceptualized as two separate, two-choice (D-N) discriminations (Jarbe and Swedberg 1982). The results also confirm suggestion that the stimulus effects of LSD and LHM are mediated by different mechanisms; the primary action of LSD is serotonergic (5-HT2), while that of LHM is dopaminergic (White 1986).Some of these data were presented at the meeting of the Society of Neuroscience, Toronto, 1988 (Satellite Session of the Society for the Stimulus Properties of Drugs). They were also submitted (in somewhat different form) to the Graduate School of the University of South Carolina in partial fulfillment of the requirements for an MA degree (in Experimental Psychology)  相似文献   
80.
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