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   719篇
  免费   34篇
  国内免费   1篇
耳鼻咽喉   8篇
儿科学   28篇
妇产科学   9篇
基础医学   85篇
口腔科学   68篇
临床医学   101篇
内科学   133篇
皮肤病学   2篇
神经病学   24篇
特种医学   26篇
外科学   59篇
综合类   2篇
预防医学   110篇
眼科学   18篇
药学   34篇
中国医学   1篇
肿瘤学   46篇
  2023年   4篇
  2022年   4篇
  2021年   3篇
  2020年   12篇
  2019年   11篇
  2018年   10篇
  2017年   18篇
  2016年   13篇
  2015年   15篇
  2014年   17篇
  2013年   42篇
  2012年   41篇
  2011年   36篇
  2010年   18篇
  2009年   27篇
  2008年   33篇
  2007年   47篇
  2006年   35篇
  2005年   24篇
  2004年   22篇
  2003年   26篇
  2002年   33篇
  2001年   32篇
  2000年   26篇
  1999年   33篇
  1998年   4篇
  1996年   4篇
  1994年   4篇
  1993年   4篇
  1992年   17篇
  1991年   7篇
  1990年   9篇
  1989年   11篇
  1988年   15篇
  1987年   14篇
  1986年   5篇
  1985年   5篇
  1984年   5篇
  1983年   5篇
  1982年   3篇
  1979年   9篇
  1978年   5篇
  1977年   7篇
  1976年   4篇
  1975年   5篇
  1974年   6篇
  1973年   6篇
  1972年   3篇
  1971年   2篇
  1970年   3篇
排序方式: 共有754条查询结果,搜索用时 11 毫秒
31.
32.
33.
107 Swedish subjects, all 20 years old, were studied for the first three years (1990-1992) after they had left the organised dental care for children and adolescents (which is free of charge for all youth through the age of 19). They were registered in four different risk-grouping systems in order to estimate the amount of their future dental care. Three of the systems used registrations from the Public Dental Service records and in the fourth one a dentist made a subjective estimation. The follow-up used dental insurance claims to study performed treatments, courses of treatments and cost. The risk group system that used subjective estimations appeared to be the one that most accurately predicted the actual dental care consumption. Approximately 70% of the subjects received some kind of dental care during the three years. The distribution was not confined to any particular risk group. Ten per cent had received complete dental care annually. Twenty-five per cent went to a private dentist and 75% continued to go to the Public Dental Service. Those who went to a private dentist received substantially more treatment and the annual cost was a little more than twice as much as in the Public Dental Service.  相似文献   
34.
Summary The volumes of the auditory brainstem nuclei and age-related auditory brainstem response (ABR) thresholds were analyzed in homozygote (je/je) and heterozygote (je/+) jerker mutant mice. Altogether 97 mice were used in the study. Je/je mice never develop any hearing. The dorsal (DCN) and ventral (VCN) cochlear nuclei were found to have stopped their growth at 56 days after birth. In je/+ mutants, ABR thresholds remained normal or nearnormal for 3–6 months, whereas VCN and DCN volumes remained unchanged at least after 56 days after birth. There is no significant difference in DCN volume in je/je and je/+ mice. However, the VCN volume and the cross-sectional area of globular cells were both significantly larger in je/+ than in je/je mice (P<0.01). These findings show that auditory deprivation during the maturation of hearing in je/je mutants causes an incomplete maturation of only the ventral cochlear nucleus.Supported by grants from the Swedish Medical Research Council (12X-7305), the National Institutes of Health (NS-19238), the Foundation Tysta Skolan (MA), the Ragnar and Torsten Söderberg Foundation (MA) and the University of Umeå  相似文献   
35.
OBJECTIVE: To determine the effect of orlistat, a new lipase inhibitor, on long-term weight loss, to determine the extent to which orlistat treatment minimizes weight regain in a second year of treatment, and to assess the effects of orlistat on obesity-related risk factors. RESEARCH METHODS AND PROCEDURES: This was a 2-year, multicenter, randomized, double-blind, placebo-controlled study. Obese patients (body mass index 28 to 43 kg/m2) were randomized to placebo or orlistat (60 or 120 mg) three times a day, combined with a hypocaloric diet during the first year and a weight maintenance diet in the second year of treatment to prevent weight regain. Changes in body weight, lipid profile, glycemic control, blood pressure, quality of life, safety, and tolerability were measured. RESULTS: Orlistat-treated patients lost significantly more weight (p<0.001) than placebo-treated patients after Year 1 (6.6%, 8.6%, and 9.7% for the placebo, and orlistat 60 mg and 120 mg groups, respectively). During the second year, orlistat therapy produced less weight regain than placebo (p = 0.005 for orlistat 60 mg; p<0.001 for orlistat 120 mg). Several obesity-related risk factors improved significantly more with orlistat treatment than with placebo. Orlistat was generally well tolerated and only 6% of orlistat-treated patients withdrew because of adverse events. Orlistat leads to predictable gastrointestinal effects related to its mode of action, which were generally mild, transient, and self-limiting and usually occurred early during treatment. DISCUSSION: Orlistat administered for 2 years promotes weight loss and minimizes weight regain. Additionally, orlistat therapy improves lipid profile, blood pressure, and quality of life.  相似文献   
36.
OBJECTIVE: To assess total daily energy expenditure (TDEE) and patterns of physical activity among Swedish male and female adolescents and to relate the amount and intensity of physical activity to existing recommendations (energy expenditure equal to or above 12.4 kJ/kg/day or accumulation of 30 min/day in moderate physical activity equal to 4.5 times sedentary energy expenditure or more). DESIGN: TDEE, physical activity level (PAL=TDEE/BMR), energy expenditure (EE) and time spent in different intensities of physical activity were assessed by using minute-by-minute heart rate monitoring in combination with laboratory measured sedentary energy expenditure (SEE) and peak oxygen uptake. SETTING: Department of Physical Education and Health, Orebro University, and Department of Clinical Physiology, Orebro Medical Centre Hospital, Sweden. SUBJECTS: Eighty-two 14-15 y old adolescents (42 boys, 40 girls) from the city of Orebro, randomly selected through a two-stage sampling procedure. RESULTS: TDEE was 12.8 MJ/day and 10.0 MJ/day for boys and girls respectively (P<0.001) and PAL was 1.74 and 1.67 (NS). Forty-four percent and 47%, respectively, of TDEE referred to EE in physical activity, of which 70% for both genders referred to light physical activity (corresponding to <4.5 times SEE). Eleven boys and 14 girls had an EE lower than 12.4 kJ/kg/day and/or did not accumulate 30 min/day in physical activity >/=4.5 SEE. Those (n=20) with the highest PAL values (>2.01 and 1.81, respectively) spent 149 min/day at a >/=4.5 SEE intensity level compared to 40 min/day for those (n=30) with the lowest PAL values (<1.55 and 1.45, respectively). CONCLUSIONS: Swedish adolescent boys and girls are similarly physically active. The major amount of time devoted to physical activity refers to light physical activity. At least thirty percent of adolescents seem not to achieve appropriate levels of physical activity considered to be beneficial for health. SPONSORSHIP: Orebro County Council, The Public Health Committee of Stockholm County Council, Sweducation Foundation.  相似文献   
37.
Adiponectin (also called AdipoQ, gelatin-binding protein 28, Acrp30) DNA sequence variants were determined in 96 unrelated female subjects with severe obesity (mean body mass index [BMI], 42.3 kg/m2) and in 96 non-obese female controls (mean BMI, 23.0 kg/m2) from the Swedish Obese Subjects (SOS) cohort. A single base substitution (T45G) at codon 15 of exon 2 resulting in no change in amino acid (Gly15Gly) was found in equal frequencies among obese and control subjects. However, this polymorphism was associated with serum cholesterol and waist circumference (P=.023 and.043, respectively) in the obese group. A IVS2 + G62T sequence variation was also identified, but had similar prevalence rates in obese and control subjects. Blood glucose was highest in the obese female subjects who were homozygotes for the G allele (GG) of the IVS2 + G62T polymorphism (N=56; P=.033) and all the diabetics (n=6) in this sample were in this group. IVS2 + G62T polymorphism was also associated with BMI (P=.014), diastolic blood pressure (P=.009), and sagittal diameter (P=.032). A missense point mutation at codon 111 (Tyr111His) was not associated with any obesity-related phenotypes. In conclusion, adiponectin DNA sequence variations might play a role in the complications of morbid obesity and should be further investigated.  相似文献   
38.
Results from cross-sectional and longitudinal studies such as Alimentación y Valoración del Estado Nutricional en Adolescentes: Food and Assessment of the Nutritional Status of Spanish Adolescents (AVENA) and the European Youth Heart Study (EYHS) respectively, highlight physical fitness as a key health marker in childhood and adolescence. Moderate and vigourous levels of physical activity stimulate functional adaptation of all tissues and organs in the body (i.e. improve fitness), thereby also making them less vulnerable to lifestyle-related degenerative and chronic diseases. To identify children and adolescents at risk for these major public health diseases and to be able to evaluate the effects of alternative intervention strategies in European countries and internationally, comparable testing methodology across Europe has to be developed, tested, agreed upon and included in the health monitoring systems currently under development by the European Commission (EC): the Directorate General for Health and Consumer Affairs (DG SANCO); the Statistical Office of the European Communities (EUROSTAT), etc. The Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study group plans, among other things, to describe the health-related fitness of adolescents in a number of European countries. Experiences from AVENA and EYHS will be taken advantage of. This review summarises results and experiences from the developmental work so far and suggests a set of health-related fitness tests for possible use in future health information systems.On behalf of the HELENA Study Group  相似文献   
39.
Aim A low level of physical activity is a risk factor for several chronic diseases, and evidence suggests that physical activity levels are in decline. Reversing this trend will involve a change in behaviour for most people. However, the associations between many psychosocial determinants and physical activity are not well understood. This study aims to examine the relationship between self-reported physical activity and perceived self-efficacy and stages of change.Subjects and methods Students attending a third-level college in Dublin, Ireland, were recruited to participate in the study (n=201, mean age 20.7 years). Physical activity was assessed with the use of the long format, self-administered International Physical Activity Questionnaire (IPAQ), and subjects were assigned to tertiles of activity. Self-efficacy and stages of change (in relation to increasing physical activity) were assessed by means of a questionnaire.Results Males reported more physical activity, had higher self-efficacy and were more likely to be in the action or maintenance stages of change. The stages of change were positively correlated with tertiles of reported activity (P<0.001) in both genders. The correlation between activity and positive self-efficacy was significant (P<0.001) for males but not for females.Conclusion Self-efficacy may be an important determinant of physical activity, and awareness of the stages of change may also help to explain physical activity although this effect appears to differ by gender. Physical activity is a complex behaviour, and the factors that determine it must be better understood if health promotion strategies to increase it are to be successful.  相似文献   
40.
The European Youth Heart Study (EYHS) addresses cardiovascular disease risk factors and their determinants in European children and adolescents. The Swedish part of the study began with cross-sectional data collection in 9- and 15-year-old schoolchildren in 1998–1999 (EYHS-I). Repeated observations of the key indicators were performed in 2004–2005 (EYHS-II). The purpose of this study was to assess potential dropout effects in EYHS-II. Participants in both EYHS-I and EYHS-II (n=459) were compared with dropouts who participated only in the EYHS-I (n=678) in relation to baseline physical activity, cardiorespiratory fitness and socioeconomic and anthropometric characteristics. Bivariate comparisons were performed using chi-square tests and gamma tests for nominal and ordinal data, respectively. Continuous data were compared by t tests and Mann−Whitney tests depending on the distribution. The Bonferroni correction was used to control for multiple hypothesis testing. Multiple logistic regression with backward elimination of variables was applied to study independent effects of variables on the probability of becoming a dropout. Analyses were performed separately for the younger and older age groups. The dropout proportion in EYHS-II was 60%. Subjects from the older age group were less likely to participate in the follow-up study (32% vs. 50%, p<0.001). In bivariate analyses, only maternal education was associated with dropout rates in the younger age group after Bonferroni correction. Males were more likely to drop out in both younger [odds ratio (OR)=1.72; 95% confidence interval (CI): 1.10, 2.96] and older (OR=1.96; 95% CI: 1.09, 3.54) age groups while basic maternal education was associated with outcome only in the younger group (OR=4.31; 95% CI: 1.78, 2.95) in regression analysis. The Swedish EYHS-II had high dropout rate after EYHS-I, but the dropouts did not differ from the participants in relation to physical activity, physical fitness, and anthropometric indices. Males were more likely to drop out than were females in both age groups. Differential dropout in relation to maternal education was observed in the younger age group.  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