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   6469篇
  免费   510篇
  国内免费   40篇
耳鼻咽喉   91篇
儿科学   183篇
妇产科学   139篇
基础医学   827篇
口腔科学   180篇
临床医学   742篇
内科学   1317篇
皮肤病学   77篇
神经病学   602篇
特种医学   503篇
外国民族医学   4篇
外科学   624篇
综合类   90篇
预防医学   598篇
眼科学   219篇
药学   562篇
中国医学   6篇
肿瘤学   255篇
  2021年   56篇
  2019年   62篇
  2018年   72篇
  2017年   54篇
  2016年   75篇
  2015年   87篇
  2014年   138篇
  2013年   179篇
  2012年   289篇
  2011年   322篇
  2010年   176篇
  2009年   189篇
  2008年   280篇
  2007年   309篇
  2006年   267篇
  2005年   292篇
  2004年   235篇
  2003年   250篇
  2002年   217篇
  2001年   241篇
  2000年   203篇
  1999年   189篇
  1998年   92篇
  1997年   77篇
  1996年   73篇
  1995年   53篇
  1994年   74篇
  1993年   62篇
  1992年   138篇
  1991年   149篇
  1990年   160篇
  1989年   176篇
  1988年   152篇
  1987年   117篇
  1986年   122篇
  1985年   108篇
  1984年   98篇
  1983年   60篇
  1979年   77篇
  1978年   72篇
  1977年   58篇
  1976年   46篇
  1975年   48篇
  1974年   55篇
  1973年   62篇
  1972年   68篇
  1971年   52篇
  1970年   47篇
  1968年   45篇
  1967年   50篇
排序方式: 共有7019条查询结果,搜索用时 15 毫秒
51.
OBJECTIVE: The objective is to evaluate the sonographic characteristics of Morton's neuromas and the usefulness of sonography in detecting them. MATERIALS AND METHODS: Thirty intermetatarsal spaces were evaluated with sonography to diagnose Morton's neuromas. The prospective sonographic reports were correlated with surgical and pathologic findings. Each sonogram was then blindly and retrospectively reviewed to characterize mass echotexture, location, size, and continuity with the plantar digital nerve when present. RESULTS: Surgery revealed 27 Morton's neuromas, one synovial cyst with infarcted tissue, one ganglion cyst, and one giant cell tumor of the tendon sheath. The prospective sonographic reports correctly identified neuromas in 85% of the cases. Retrospectively, 79.2% (19/24) of the neuromas were characterized as hypoechoic compared with muscle, whereas 12.5% (3/24) were of mixed echotexture and 8.3% (2/24) were anechoic. One half (50%) of the neuromas were located dorsal to the plantar aspect of the metatarsal heads, and 50% were both dorsal and plantar to this level. No statistical difference in height and width was found between neuromas and nonneuromas; however, nonneuromas were statistically greater in length than neuromas. All 15 masses in which presumed plantar digital nerve continuity with the mass was identified were neuromas. CONCLUSION: Sonography can reveal a Morton's neuroma in 85% of cases. Identification of the presumed plantar digital nerve in continuity with the mass improves diagnostic confidence. The finding of an interdigital mass greater than 20 mm in length should raise suspicion of an abnormality other than a neuroma.  相似文献   
52.
53.
We tested swab specimens from pets in households in Ontario, Canada, with human COVID-19 cases by quantitative PCR for SARS-CoV-2 and surveyed pet owners for risk factors associated with infection and seropositivity. We tested serum samples for spike protein IgG and IgM in household pets and also in animals from shelters and low-cost neuter clinics. Among household pets, 2% (1/49) of swab specimens from dogs and 7.7% (5/65) from cats were PCR positive, but 41% of dog serum samples and 52% of cat serum samples were positive for SARS-CoV-2 IgG or IgM. The likelihood of SARS-CoV-2 seropositivity in pet samples was higher for cats but not dogs that slept on owners’ beds and for dogs and cats that contracted a new illness. Seropositivity in neuter-clinic samples was 16% (35/221); in shelter samples, 9.3% (7/75). Our findings indicate a high likelihood for pets in households of humans with COVID-19 to seroconvert and become ill.  相似文献   
54.
A group of 57 children with recent onset of insulin-dependent diabetes mellitus was studied over 18 months. Compliance with the prescribed diabetic treatment deteriorated over this period. Adolescents (aged 13 to 15 years) were less compliant than preadolescents (aged 9 to 12 years). Initial patient reports of self-esteem, perceived competence, social functioning, behavioral symptoms, and their adjustment to diabetes predicted subsequent compliance behaviors. The findings highlight the linkage of child personality and adjustment with self-care of diabetes, and suggest that psychosocial assessment soon after diabetes is diagnosed may help identify patients at risk for later compliance problems.  相似文献   
55.
The purpose of this study was to evaluate adherence and identify predictors of adherence to a raw vegan diet (i.e., uncooked plant foods) following a stay at a raw vegan institute. In this cohort study of guests at a raw vegan institute, subjects completed written questionnaires upon arrival and 12 weeks later. Of 107 eligible guests, 84 participated. Mean age was 54 years, 23 were male, and 73 white. Fifty-one completed the 12-week follow-up. Eight (16%) reported their diet to be 80% raw vegan at baseline and 14 (28%) at follow-up. Based on a raw vegan dietary adherence score (range 0-42) created for this study, mean adherence (SD) increased from 15.1 (5.4) to 17.0 (5.8) over 12 weeks (p=0.03). Baseline predictors of adherence included: education (beta=0.95), severity of disease (beta=0.98), and self-efficacy to adhere (beta=0.72). Future interventions that evaluate this diet should address self-efficacy, an important, potentially remediable predictor of adherence.  相似文献   
56.
57.
A 17-year-old male with systemic lupus erythematosus presented with clinical signs of severe constrictive pericarditis that was confirmed by cardiac catheterization. At surgery, a fibrous pericardium was removed, followed by complete relief of symptoms. Immunopathology of the pericardial tissue revealed deposition of IgG, IgM, and C3. A review of the literature produced only three similar cases. Although rare, constrictive pericarditis, a potentially life threatening complication, may occur in systemic lupus erythematosus presumably with an immunological basis.  相似文献   
58.
59.

A stratified random sample of midlife Baby Boom women, ages 35–42, was compared with a group of older midlife women, ages 43‐. 55. The sample consisted of 992 women who had graduated between the years of 1955 and 1975 from a large university in southern California. Measures of anxiety and life satisfaction were administered to each year group. This served to control for the effect of age and was helpful in explaining whether the differences between the groups were age related or the result of socialization. The Baby Boom cohort of women, born after January 1, 1946, have only recently entered the ranks of midlife. They have been recognized as unique and less traditional than their older counterparts with regard to sexual freedom, career choices, and educational opportunities. Similarities and differences were found between the two groups of women. However, the results clearly revealed that the effects of socialization, rather than age, yielded the major significant variables influencing a feeling of well‐being in both cohorts of midlife women.  相似文献   
60.
The coincidence of both an obesity epidemic and an asthma epidemic among children in the United States has suggested that childhood overweight and sedentary lifestyles may be risk factors for asthma development. We therefore conducted a study of those factors among children enrolled in Head Start Centers located in areas of New York City with high asthma hospitalization rates.

Data were gathered from 547 children through an intensive home visit, and physical activity was measured on 463 children using the Actiwatch accelerometer. Data on allergy and asthma symptoms and demographic variables were obtained from parents' responses to a questionnaire and complete data were available from 433 children.

Overall physical activity was highest in warmer months, among boys, among children whose mothers did not work or attend school, and among children of mothers born in the United States. Activity was also positively associated with the number of rooms in the home. The season in which the activity data were collected modified many of the associations between demographic predictor variables and activity levels. Nearly half the children were above the range considered healthy weight. In cross-sectional analyses, before and after control for demographic correlates of physical activity, asthma symptoms were not associated with physical activity in this age group. Comparing the highest quartile of activity to the lowest, the odds ratio for asthma was 0.91 (95% CI = 0.46, 1.80).

However, the novel associations with physical activity that we have observed may be relevant to the obesity epidemic and useful for planning interventions to increase physical activity among preschool children living in cities in the northern United States.  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