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   102534篇
  免费   7522篇
  国内免费   376篇
耳鼻咽喉   1128篇
儿科学   2536篇
妇产科学   1649篇
基础医学   14487篇
口腔科学   2194篇
临床医学   10467篇
内科学   21744篇
皮肤病学   1796篇
神经病学   10914篇
特种医学   4201篇
外国民族医学   6篇
外科学   14629篇
综合类   1266篇
一般理论   73篇
预防医学   7922篇
眼科学   1723篇
药学   6913篇
中国医学   111篇
肿瘤学   6673篇
  2023年   573篇
  2022年   1085篇
  2021年   2149篇
  2020年   1320篇
  2019年   1971篇
  2018年   2424篇
  2017年   1786篇
  2016年   2133篇
  2015年   2480篇
  2014年   3264篇
  2013年   4297篇
  2012年   6651篇
  2011年   6707篇
  2010年   3963篇
  2009年   3608篇
  2008年   5926篇
  2007年   6423篇
  2006年   5955篇
  2005年   5900篇
  2004年   5509篇
  2003年   4915篇
  2002年   4871篇
  2001年   1870篇
  2000年   1780篇
  1999年   1659篇
  1998年   1223篇
  1997年   1003篇
  1996年   815篇
  1995年   817篇
  1994年   702篇
  1993年   638篇
  1992年   1152篇
  1991年   1068篇
  1990年   1010篇
  1989年   972篇
  1988年   865篇
  1987年   810篇
  1986年   831篇
  1985年   828篇
  1984年   669篇
  1983年   578篇
  1982年   552篇
  1981年   453篇
  1980年   394篇
  1979年   514篇
  1978年   406篇
  1977年   367篇
  1975年   328篇
  1974年   355篇
  1973年   343篇
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
21.
22.
23.
Background:  The term 'pigmented epithelioid melanocytoma (PEM)' was recently used for borderline melanocytic tumor/low-grade melanoma including cases previously diagnosed as human animal-type melanoma and epithelioid blue nevus. No Japanese cases have been reported.
Methods:  We reviewed 219 cases previously diagnosed as blue nevus in Japan. Common blue nevus was identified in 154 cases and cellular blue nevus in 65 cases.
Results:  We have found two Japanese cases of PEM previously diagnosed as cellular blue nevus. Two patients were female. The age at presentation was 32 and 28 years. Two lesions were on the buttock. Two cases fulfilled histological criteria proposed for PEM. There is no evidence of recurrence or metastases.
Conclusions:  PEM is a distinct melanocytic tumor and the unifying diagnostic term. PEM is present in Japanese, but these cases may be previously diagnosed as cellular blue nevus. Japanese pathologists should recognize a new concept of PEM, and when they make a diagnosis of PEM, they should be recommended sentinel lymph node sampling.  相似文献   
24.
The objectives of this study were to systematically review and meta-analyze the research literature on the association of common neurological disorders and violence. Keywords relating to neurological disorders and violence were searched between 1966 and August 2008. Case–control and cohort studies were selected. Odds ratios of violence risk in particular disorders compared with controls were combined using fixed-effects meta-analysis with the data presented in forest plots. Sensitivity analyses were conducted to identify possible differences in risk estimates across surveys. Information on risk factors for violence was extracted if replicated in more than one study. Nine studies were identified that compared the risk of violence in epilepsy or traumatic brain injury compared with unaffected controls. For the epilepsy studies, the overall pooled odds ratio for violent outcomes was 0.67 [95% confidence interval (CI) 0.46–0.96]. For traumatic brain injury, the odds ratio was 1.66 (95% CI 1.12–2.31). An additional 11 case–control studies investigated factors associated with violence in epilepsy and traumatic brain injury. It was not possible to meta-analyze these data. Comorbid psychopathology was associated with violence. Data on other neurological conditions was limited and unreplicated. In conclusion, although the evidence was limited and methodological quality varied, epilepsy and traumatic brain injury appeared to differ in their risk of violence compared with control populations. Longitudinal studies are required to replicate this review’s provisional findings that epilepsy is inversely associated with violence and that brain injury modestly increases the risk, and further research is needed to provide information on a broader range of risk factors.  相似文献   
25.
An inverse relationship between workplace status and morbidity is well established; higher job status has been associated with reduced risks of heart disease, hypertension, and injury. Most research on job status, however, has focused on salaried populations, and it remains unclear whether job status operates similarly among hourly workers. Our objectives were to examine whether hourly status itself influences risk of hypertension after adjustment for socioeconomic confounders, and to explore the role of fine-scale job grade on hypertension incidence within hourly and salaried groups. We examined data for 14,999 aluminum manufacturing employees in 11 plants across the U.S., using logistic regression with adjustment for age, sex, race/ethnicity and other individual characteristics. Propensity score restriction was used to identify comparable groups of hourly and salaried employees, reducing confounding by sociodemographic characteristics. Job grade (coded 1 through 30, within hourly and salaried groups) was examined as a more refined measure of job status. Hourly status was associated with an increased risk of hypertension, after propensity restriction and adjustment for confounders. The observed effect of hourly status was stronger among women, although the propensity-restricted cohort was disproportionately male (96%). Among salaried workers, higher job grade was not consistently associated with decreased risk; among hourly employees, however, there was a significant trend, with higher job grades more protective against hypertension. Increasing the stringency of hypertension case criteria also increased the risk of severe or persistent hypertension for hourly employees.  相似文献   
26.
27.
The cellular infiltrate present in human diseased gingiva was analyzed in biopsies from 12 patients with gingivitis or periodontitis. The samples studied had been obtained in the course of surgery at inflammatory sites remaining after institution of periodontal treatment. Histological and immunological techniques were used to identify macrophages, B-cells, plasma-cells, T-cells and T cell subsets, as well as cells expressing class II HLA membrane antigens. T-cells appeared as the predominant population, but plasma-cells were also visualized in nearly all samples. Both OKT4+ and OKT8+ cells were seen in all cases, the latter being more numerous in periodontitis patients. Interdigitating-like cells were observed, positively labelled for class II antigens, as well as macrophages which were more numerous in periodontitis patients. These results suggest the participation of all components of the immune response in gingival disease, in a way resembling chronic recurrent inflammatory diseases.  相似文献   
28.
29.
A case of esthesioneuroblastoma with an unusual clinical and radiographic presentation is reported. The presenting symptoms as well as the computed tomographic examination were compatible with a primary intracranial mass.  相似文献   
30.
BACKGROUND: The dopamine transporter (DAT) is known to be a key regulator of dopamine, and recent studies of genetics, treatment, and imaging have highlighted the role of DAT in attention-deficit/hyperactivity disorder (ADHD). The findings of in vivo neuroimaging of DAT in ADHD have been somewhat discrepant, however. METHOD: Dopamine transporter binding was measured using a highly selective ligand (C-11 altropane) and positron emission tomography (PET). The sample consisted of 47 well-characterized, treatment-na?ve, nonsmoking, non-comorbid adults with and without ADHD. Additionally, control subjects had few symptoms of ADHD. RESULTS: Results showed significantly increased DAT binding in the right caudate in adults with ADHD compared with matched control subjects without this disorder. CONCLUSIONS: These results confirm abnormal DAT binding in the striatum of adults with ADHD and provide further support that dysregulation of DAT may be an important component of the pathophysiology of ADHD.  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