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   800篇
  免费   118篇
  国内免费   1篇
耳鼻咽喉   12篇
儿科学   46篇
妇产科学   25篇
基础医学   126篇
口腔科学   5篇
临床医学   90篇
内科学   130篇
皮肤病学   6篇
神经病学   52篇
特种医学   26篇
外科学   73篇
综合类   21篇
预防医学   153篇
眼科学   9篇
药学   114篇
中国医学   1篇
肿瘤学   30篇
  2019年   7篇
  2018年   12篇
  2017年   7篇
  2016年   7篇
  2015年   11篇
  2014年   7篇
  2013年   26篇
  2012年   28篇
  2011年   39篇
  2010年   11篇
  2009年   14篇
  2008年   36篇
  2007年   32篇
  2006年   33篇
  2005年   31篇
  2004年   31篇
  2003年   24篇
  2002年   23篇
  2001年   23篇
  2000年   27篇
  1999年   30篇
  1998年   9篇
  1997年   9篇
  1996年   14篇
  1995年   13篇
  1994年   5篇
  1993年   13篇
  1992年   26篇
  1991年   23篇
  1990年   28篇
  1989年   28篇
  1988年   25篇
  1987年   14篇
  1986年   13篇
  1985年   9篇
  1984年   16篇
  1983年   21篇
  1982年   13篇
  1980年   10篇
  1979年   25篇
  1978年   14篇
  1977年   11篇
  1976年   8篇
  1975年   8篇
  1974年   8篇
  1973年   6篇
  1972年   9篇
  1970年   6篇
  1969年   8篇
  1968年   6篇
排序方式: 共有919条查询结果,搜索用时 15 毫秒
21.
22.
Positive aspects of self-compassion (i.e., self-kindness and nonjudgmental acceptance of personal experiences) as well as negative aspects (i.e., high self-criticism and self-coldness) are strong predictors of anxiety, depression, worry, and quality of life. To date, however, relatively little is known about (a) how both aspects of self-compassion change during naturalistic treatment, (b) whether and how such changes relate to symptom improvement, and (c) which processes might explain the potential benefits of self-compassion. To address these gaps, the present study examined whether relations between changes in both aspects of self-compassion and treatment outcomes in a brief partial hospital setting for acute psychology could be explained by associated changes in repetitive negative thinking (RNT), an established maladaptive cognitive process involved in anxiety and depressive disorders. In a sample of 582 people receiving cognitive-behavioral (CBT) and dialectical behavior therapy over the course of 1–2 weeks, increases in positive aspects of self-compassion and decreases in negative aspects related to improvements in depression and anxiety. RNT mediated the relationship between decreases in negative aspects of self-compassion and improvements in anxiety and depression. However, a reverse model also showed that decreases in negative aspects of self-compassion could also explain relations between RNT and depressive symptom improvement only. These findings suggest that negative aspects of self-compassion and RNT may constitute important targets for treatment in acute settings. Future studies should investigate the impact of greater focus on self-compassion on RNT and symptom improvement using longitudinal experimental designs with multiple assessment points, examining causality and directionality.  相似文献   
23.
OBJECTIVE: To examine the maternal and foetal risks of adverse pregnancy outcome in relation to maternal obesity, expressed as body mass index (BMI, kg/m(2)) in a large unselected geographical population. DESIGN: Retrospective analysis of data from a validated maternity database system which includes all but one of the maternity units in the North West Thames Region. A comparison of pregnancy outcomes was made on the basis of maternal BMI at booking. SUBJECTS: A total of 287,213 completed singleton pregnancies were studied including 176,923 (61.6%) normal weight (BMI 20--24.9), 79 014 (27.5%) moderately obese (BMI 25--29.9) and 31,276 (10.9%) very obese (BMI> or =30) women. MEASUREMENTS: Ante-natal complications, intervention in labour, maternal morbidity and neonatal outcome were examined and data presented as raw frequencies and adjusted odds ratios with 99% confidence intervals following logistic regression analysis to account for confounding variables. RESULTS: Compared to women with normal BMI, the following outcomes were significantly more common in obese pregnant women (odds ratio (99% confidence interval) for BMI 25--30 and BMI> or =30 respectively): gestational diabetes mellitus (1.68 (1.53--1.84), 3.6 (3.25--3.98)); proteinuric pre-eclampsia (1.44 (1.28--1.62), 2.14 (1.85--2.47)); induction of labour (2.14 (1.85--2.47), 1.70 (1.64--1.76)); delivery by emergency caesarian section (1.30 (1.25--1.34), 1.83 (1.74--1.93)); postpartum haemorrhage (1.16 (1.12--1.21), 1.39 (1.32--1.46)); genital tract infection (1.24 (1.09--1.41), 1.30 (1.07--1.56)); urinary tract infection (1.17 (1.04-1.33), 1.39 (1.18--1.63)); wound infection (1.27 (1.09--1.48), 2.24 (1.91--2.64)); birthweight above the 90th centile (1.57 (1.50--1.64), 2.36 (2.23--2.50)), and intrauterine death (1.10 (0.94--1.28), 1.40 (1.14--1.71)). However, delivery before 32 weeks' gestation (0.73 (0.65--0.82), 0.81 (0.69--0.95)) and breastfeeding at discharge (0.86 (0.84--0.88), 0.58 (0.56--0.60)) were significantly less likely in the overweight groups. In all cases, increasing maternal BMI was associated with increased magnitude of risk. CONCLUSION: Maternal obesity carries significant risks for the mother and foetus. The risk increases with the degree of obesity and persists after accounting for other confounding demographic factors. The basis of many of the complications is likely to be related to the altered metabolic state associated with morbid obesity.  相似文献   
24.
ObjectivesTo assess physical activity (PA), mental health and well-being of adults in the United Kingdom (UK), Ireland, New Zealand and Australia during the initial stages of National governments’ Coronavirus disease (COVID-19) containment responses.DesignObservational, cross-sectional.MethodsAn online survey was disseminated to adults (n = 8,425; 44.5 ± 14.8y) residing in the UK, Ireland, New Zealand and Australia within the first 2-6 weeks of government-mandated COVID-19 restrictions. Main outcome measures included: Stages of Change scale for exercise behaviour change; International Physical Activity Questionnaire (short-form); World Health Organisation-5 Well-being Index; and the Depression Anxiety and Stress Scale-9.ResultsParticipants who reported a negative change in exercise behaviour from before initial COVID-19 restrictions to during the initial COVID-19 restrictions demonstrated poorer mental health and well-being compared to those demonstrating either a positive-or no change in their exercise behaviour (p < 0.001). Whilst women reported more positive changes in exercise behaviour, young people (18-29y) reported more negative changes (both p < 0.001). Individuals who had more positive exercise behaviours reported better mental health and well-being (p < 0.001). Although there were no differences in PA between countries, individuals in New Zealand reported better mental health and well-being (p < 0.001).ConclusionThe initial COVID-19 restrictions have differentially impacted upon PA habits of individuals based upon their age and sex, and therefore have important implications for international policy and guideline recommendations. Public health interventions that encourage PA should target specific groups (e.g., men, young adults) who are most vulnerable to the negative effects of physical distancing and/or self-isolation.  相似文献   
25.
OBJECTIVE: To characterize the pattern of involvement of osteoarthritis (OA) of the hand among men and women of the same age. METHODS: Structured hand examinations were performed on 1,467 men and 1,519 women who were age 53 years and born in England, Scotland, or Wales during the first week of March 1946 (identified through the United Kingdom National Survey of Health and Development). OA at each joint site was characterized using a previously validated examination schedule. The interrelationship of involvement of different hand joints was analyzed by logistic regression and cluster analyses. RESULTS: There was clear evidence of polyarticular involvement in the hand joints of both the men and the women. Among the women, 161 subjects had >/=4 joints involved, compared with only 41 subjects expected in this category (P < 0.001). Among the men, 87 subjects were observed to have >/=4 joints involved, in contrast with only 7 subjects expected (P < 0.001). The pattern of hand joint involvement (characterized by clustering primarily by row and symmetric joint involvement, rather than clustering by ray) was found to be almost identical between the men and the women. CONCLUSION: This study confirms the existence of a polyarticular subset of OA among men that has characteristics similar to those of the variant observed among women. The data suggest that the genetic or metabolic influences underlying this particular variant of OA acts similarly in both sexes.  相似文献   
26.
Intact DNA molecules extracted from HSV-1 (herpes simplex virus 1, human herpes virus 1) strain MP virions have a molecular weight of approximately 97 X 10(6), but cleavage with the HinIII restriction enzyme yields fourteen fragments with summed molecular weights of 160 X 10(6). Six "major" fragments occur once in every molecule in the population and account for 60% of the genetic information. Four "minor" fragments are present in amounts equivalent to one copy for every two genomes (0.5 molar ratio) and the other four occur only once in every four molecules (0.25 molar ratio). The minor fragments can be arranged into four equimolar sets, each with summed molecular weights that account for the remaining 40% of the genome. Treatment with lambda 5' exonuclease revealed that all molecules contain 0.5 molar ratio fragments at both termini. These observations and the results of similar analyses of the EcoRI and double HinIII/EcoRI digests indicate that there are four distinct structural forms of HSV DNA which differ only in the relative orientations of two subregions, designated L and S. The L and S segments consist of 82 and 18% of the sequences, respectively, and each has inverted terminally redundant regions that correspond to the internal duplications observed by electron microscopy. The DNA from other strains of HSV-1 and 2 also consists of equal proportions of all four possible permutations of the L and S segments. These unusual features of HSV DNA molecules have novel implications with regard to the genetic map and the mode of replication and evolution of herpes simples viruses.  相似文献   
27.
Foot‐and‐mouth disease (FMD) is endemic in Kenya where four serotypes (O, A, SAT 1 and SAT 2) of the virus are currently in circulation. Within 2010 and 2011, the National Laboratory recorded an increase in the number of FMD outbreaks caused by serotype O virus. The characteristics of these viruses were determined to ascertain whether these were independent outbreaks or one single strain spreading throughout the country. The sequences of the complete VP1‐coding region were analysed from viruses sampled within different areas of Kenya during 2010 and 2011. The results indicated that the 2010 to 2011 outbreaks in Kenya were caused by four independent strains. By comparison with earlier type O isolates from Eastern Africa, it was apparent that the outbreaks were caused by viruses from three different lineages of topotype EA‐2 and a fourth virus strain belonging to topotype EA‐4. The topotypes EA‐1 and EA‐3 were not detected from these outbreaks. Implications of these results for FMD control in Eastern Africa are discussed.  相似文献   
28.
29.
30.
Previous twin studies have suggested a possible developmental dissociation between genetic influences on word recognition and spelling deficits, wherein genetic influence declined across age for word recognition, and increased for spelling recognition. The present study included two measures of word recognition (timed, untimed) and two measures of spelling (recognition, production) in younger and older twins. The heritability estimates for the two word recognition measures were .65 (timed) and .64 (untimed) in the younger group and .65 and .58 respectively in the older group. For spelling, the corresponding estimates were .57 (recognition) and .51 (production) in the younger group and .65 and .67 in the older group. Although these age group differences were not significant, the pattern of decline in heritability across age for reading and increase for spelling conformed to that predicted by the developmental dissociation hypothesis. However, the tests for an interaction between genetic influences on word recognition and spelling deficits as a function of age were not significant. Edited by Stacey Cherny  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