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   16966篇
  免费   1415篇
  国内免费   293篇
耳鼻咽喉   30篇
儿科学   1488篇
妇产科学   959篇
基础医学   1540篇
口腔科学   172篇
临床医学   1566篇
内科学   2226篇
皮肤病学   56篇
神经病学   965篇
特种医学   394篇
外国民族医学   1篇
外科学   1180篇
综合类   1713篇
一般理论   1篇
预防医学   3359篇
眼科学   147篇
药学   1901篇
  5篇
中国医学   450篇
肿瘤学   521篇
  2023年   320篇
  2022年   358篇
  2021年   757篇
  2020年   608篇
  2019年   706篇
  2018年   614篇
  2017年   659篇
  2016年   607篇
  2015年   588篇
  2014年   1064篇
  2013年   1434篇
  2012年   907篇
  2011年   1007篇
  2010年   826篇
  2009年   807篇
  2008年   888篇
  2007年   798篇
  2006年   662篇
  2005年   615篇
  2004年   518篇
  2003年   473篇
  2002年   367篇
  2001年   328篇
  2000年   264篇
  1999年   213篇
  1998年   197篇
  1997年   154篇
  1996年   127篇
  1995年   132篇
  1994年   140篇
  1993年   116篇
  1992年   111篇
  1991年   100篇
  1990年   94篇
  1989年   72篇
  1988年   72篇
  1987年   72篇
  1986年   72篇
  1985年   126篇
  1984年   109篇
  1983年   87篇
  1982年   76篇
  1981年   74篇
  1980年   70篇
  1979年   59篇
  1978年   52篇
  1977年   27篇
  1976年   34篇
  1975年   23篇
  1973年   21篇
排序方式: 共有10000条查询结果,搜索用时 702 毫秒
51.
Early catch-up growth and subsequent overweight are suggested to be associated with later cardiovascular diseases and later type II diabetes. However, the impact of early catch-up growth and childhood overweight on the development of asthma has been less studied, particularly in children born with very low birth weight (VLBW). A birth cohort of 74 VLBW children (birth weight < or = 1500 g) was followed from birth and investigated on asthma at 12 yr of age. Early rapid weight gain was in one way defined as an increase of weight > or =1 standard deviation score (SDS) at 6 months of corrected postnatal age. Current overweight was defined by body mass index (BMI) exceeding 21.2 and 21.7 kg/m(2), respectively, for boys and girls at 12 yr of age. Current asthma was diagnosed by a pediatrician, according to asthma ever in combination with a positive response to hypertonic saline bronchial provocation test and/or wheeze at physical examination at 12 yr old. Being overweight at 12 yr of age was associated with an increased risk for current asthma in the VLBW children [crude odds ratio (OR): 5.5, 95% confidence interval (CI): 1.3-22.2]. After adjustment for early weight gain and neonatal risk, the OR of overweight increased nearly three times (adjusted OR: 15.3, 95% CI: 2.5-90.6). Early rapid weight gain seemed to be inversely associated with current asthma (adjusted OR: 0.49 for an increase of weight equal to 1 SDS, 95% CI: 0.23-1.02, p = 0.06). In addition, early rapid weight gain was inversely associated with the magnitude of bronchial responsiveness at 12 yr (coefficient -1.15, p < 0.01). There was a strong and positive association between overweight and asthma at 12 yr of age in the VLBW children. This strong association had been reduced by early rapid weight gain, possibly via the reduction of bronchial responsiveness.  相似文献   
52.
目的 探讨抗精神病药(APD)引起患者体质量增加及其相关因素。方法 对6 7例首次住院单用APD治疗的精神分裂症患者进行住院及出院后4个月的随访评估。结果 各时点体质量增加与GI评分无相关性,在出院时与BPRS、SAPS减分值有相关性,而随访期与SANS减分值有相关意义。逐步回归分析显示,在α=0 .0 5水平上,进入回归方程的因素依次为:APD品种,最大服药剂量与服药时间的积,阴性症状,病前1a最佳功能水平。结论 APD治疗中的体质量增加是与疗效无关的药物不良反应,受药物、精神症状及综合社会心理因素等方面的影响,而饮食与活动的中介作用不应低估。控制体质量增加有重要的医学及社会意义。  相似文献   
53.
Serum and red blood cell folate in depression   总被引:2,自引:0,他引:2  
Serum folate concentrations were estimated in patients with major depressive disorders, lithium-treated patients, detoxified alcoholic patients and normal controls. Red blood cell (RBC) folate concentrations were also estimated in subgroups of patients with major depressive disorder and normal controls. Results showed significantly lower serum and RBC folate concentrations in patients with major depressive disorder than in normal controls. Lower serum folate concentrations were associated with greater severity of depression. There was no association between serum and RBC folate concentrations and endogenicity of depression or the presence of weight loss.  相似文献   
54.
PURPOSE: Obesity has become a health-care crisis in the United States. Adolescent obesity is now one of the most common childhood disorders, with 4.7 million American adolescents having a body mass index (BMI) greater than the 95th percentile. Most patients do not respond to diet modification or exercise programs and attention is now turning toward surgery as a source of weight loss in adolescents. Few studies have looked at the overall morbidity and mortality of weight loss surgery in this patient population. METHODS: This is a retrospective study of medical charts of 15 bariatric surgical procedures performed on 14 adolescents without known genetic syndromes associated with severe childhood obesity from 1971 to 2001 at the University of Minnesota. Procedures performed on these patients included vertical banded gastroplasty (n = 7), Roux-en-Y gastric bypass (n = 5), and jejunoileal bypass (n = 3). Jejunoileal bypass procedures were performed from 1971 to 1977, after which time this procedure was abandoned. Patient age ranged from 13 to 17 years (mean, 15.7 years). Mean follow-up time was 6 years, with 9 patients available for long-term follow-up. RESULTS: All procedures were performed using an open technique by 1 surgeon. There were no perioperative deaths; complications included 1 case of wound infection, 2 episodes of dumping syndrome that resolved without revision, 1 episode of hypoglycemia, and 1 case of short-term electrolyte imbalance in a patient who underwent jejunoileal bypass. The average BMI dropped from 58.5 +/- 13.7 to 32.1 +/- 9.7 kg/m(2) (P < .01)--a 45% reduction. CONCLUSIONS: Surgery for morbid obesity is safe and results in significant weight loss in adolescents who fail medical therapy.  相似文献   
55.
M. Sivak 《Obesity reviews》2006,7(3):295-296
Caloric consumption in a society with readily available food is likely to be approximately proportional to the number of hours of being awake. Thus, replacing 1 h of inactive wakefulness (e.g. watching TV), with sleeping is likely to result in a substantial reduction in caloric intake. Calculations are presented to illustrate the possible benefits of such a switch on weight reduction.  相似文献   
56.
Summary There are some occasions when it is better to use the Laplacian of the scalp voltages (e.g., for topographic displays and dipole source localization) and other occasions when it is better to use the original voltages (e.g., for comparison to non-Laplacian topography maps). This paper presents a simple algorithm for going between these two representations of the data. The inverse Laplacian involves iterative feedback. An Excel spreadsheet implementation of the algorithm is presented.This research was supported by grant AFOSR 89-0238 from the Air Force Office of Sponsored Research.  相似文献   
57.
OBJECTIVES: To assess the effect of a medically induced abortion (MA) on birth weight in the first subsequent pregnancy. METHODS: Pregnant women who had had a MA, a surgical abortion (SA), or primigravidas with no history of abortion (NA), were recruited for a prospective cohort study between July 1998 and February 2001. The sample for the present analysis included 12995 singleton live births at term. RESULTS: The overall incidence rate of low birth weight (LBW) was 1.0%. The rates of LBW in the MA, SA, and NA groups were 1.0%, 0.9%, and 1.2, respectively. There were no significant differences in LBW rates between the MA and SA groups, neither between the MA and NA. Logistic regression analysis was used to estimate the effects of MA on birth weight, and we found no relationship between risk of LBW and MA. CONCLUSIONS: We did not find a statistically significant relationship between a history of one medically induced abortion and LBW for the first subsequent term pregnancy.  相似文献   
58.
The chronic exposure of rats to a schedule of operant water reinforcement coupled with chronically restricted access to water sensitized the animals to intermittentd-amphetamine injections (0.31–2.5 mg/kg with intervals of 12–23 days between any two injections) in such a way that this drug came to produce catastrophic losses of body weight (32.4% of control levels). In the sessions whend-amphetamine was administered, the rats were also given a total of 12 brief electric shocks. Loss of body weight was unaccompanied by parallel changes in operant behavior performance, or in food or water intake. Remarkably, in other studies with the same interventions (sham schedule sessions, water deprivation, and foot shocks), with the exception that reinforcers were never delivered,d-amphetamine did not produce catastrophic falls in body weight. This super-reactivity tod-amphetamine toxicity may be mediated by a possible stressor action of the schedule of reinforcement. Its mechanism might be analogous to the known sensitization produced by classical experimental stressor stimuli to the repeated administration ofd-amphetamine.  相似文献   
59.
在营养调查的基础上,以975名北方籍和921名南方籍青年为代表,以实测身高体重为依据,分别推出了理想体重计算公式。北方理想体重(kg)=[身高(cm)-150]×0.6+50;南方理想体重(kg)=[身高(cm)-150]×0.6+48。为检验样本的代表性,又另取北方籍783名青年和南方籍883名青年进行了验证,结果表明,推出的计算公式有较好的代表性。用推出的计算公式分别对1464名北方青年和2264名南方青年的身高体重进行分析,结果表明,新推出的计算公式比以往的计算公式更符合我国的情况,因而更具有实用意义。  相似文献   
60.
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