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   8264篇
  免费   712篇
  国内免费   20篇
耳鼻咽喉   56篇
儿科学   275篇
妇产科学   113篇
基础医学   963篇
口腔科学   174篇
临床医学   938篇
内科学   1641篇
皮肤病学   114篇
神经病学   462篇
特种医学   676篇
外科学   1080篇
综合类   156篇
一般理论   1篇
预防医学   882篇
眼科学   101篇
药学   614篇
中国医学   4篇
肿瘤学   746篇
  2023年   49篇
  2021年   114篇
  2020年   75篇
  2019年   109篇
  2018年   148篇
  2017年   105篇
  2016年   133篇
  2015年   126篇
  2014年   190篇
  2013年   273篇
  2012年   366篇
  2011年   348篇
  2010年   237篇
  2009年   198篇
  2008年   332篇
  2007年   384篇
  2006年   337篇
  2005年   308篇
  2004年   310篇
  2003年   274篇
  2002年   278篇
  2001年   269篇
  2000年   287篇
  1999年   223篇
  1998年   182篇
  1997年   141篇
  1996年   139篇
  1995年   134篇
  1994年   125篇
  1993年   124篇
  1992年   195篇
  1991年   171篇
  1990年   166篇
  1989年   175篇
  1988年   193篇
  1987年   176篇
  1986年   130篇
  1985年   159篇
  1984年   118篇
  1983年   108篇
  1982年   78篇
  1981年   70篇
  1980年   64篇
  1979年   98篇
  1978年   82篇
  1977年   64篇
  1976年   67篇
  1975年   50篇
  1974年   55篇
  1973年   62篇
排序方式: 共有8996条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Histologic sections (minimum of four sections per patient) from 211 patients with neuroblastoma were reviewed. The tumors were resected before therapy, which was standardized according to age and stage. Low mitotic rate (MR) (less than or equal to ten per ten high-power fields) and calcification emerged as the most significant prognostic features after statistical analysis by stepwise log-rank tests (P less than 0.0001 and P = 0.0065, respectively). Histologic Grades 1, 2, and 3 were defined on the basis of the presence of both, any one, or none of these two prognostic features, respectively (Grade 3 had absence of low MR, i.e., these tumors had high MR [greater than ten per ten high-power fields]). Statistically significant differences in survival were observed in the grades after adjusting for age and stage (P less than 0.001). The degree of differentiation, although significant by itself, was no longer significant after adjusting for the grades. Age groups (less than or equal to 1 versus greater than 1 year of age), which also emerged as an independent prognostic feature (P less than 0.001), were linked with the grades to define two risk groups as follows: (1) a low-risk (LR) group consisting of patients in both age groups with Grade 1 tumors and patients 1 year of age or younger with Grade 2 tumors and (2) a high-risk (HR) group consisting of patients older than 1 year of age with Grade 2 tumors and patients in both age groups with Grade 3 tumors. The difference in survival between LR (160 cases) and HR groups (51 cases) was statistically significant (P less than 0.001). Concordance between these LR and HR groups and the Shimada classification was observed in 84% of cases. The new histologic grading system has the following advantages: (1) use of familiar terminology and histologic features in the grading system and (2) relative ease of assessment because the degree of differentiation does not need to be determined. The grading system should be tested on a new data set with an appropriate histologic sample of similar size to confirm these results.  相似文献   
5.
6.
CONTEXT: The limited information available on the oral health status of rural children in the United States makes it difficult to devise policy strategies to address perceived problems. PURPOSE: To document the oral health status and dental care utilization of US children by place of residence, METHODS: Data from National Health Interview Surveys for 1995, 1997, and 1998, and from the third National Health and Nutrition Examination Survey (1988-1994) were analyzed. FINDINGS: Children residing in rural areas were more likely to be uninsured for dental care than were children from urban areas (41.1% versus 34.7%). A greater percentage of rural than urban children reported unmet dental needs (7.5% versus 5.6%); there was no difference in self-reported poor dental status. Urban children were more likely than rural children to have visited the dentist in the past year (73.6% versus 69.9%) and were also more likely to be regular users of dental care (61.7% versus 51.4%). Differences in percentage of rural and urban children with caries lesions and caries experience were not significant. CONCLUSIONS: Children residing in rural areas have less access to and utilization of dental care compared to children residing in urban areas. Moreover, poor rural children display less utilization of dental services than poor urban children. Differences in the sum of decayed and filled primary teeth and the sum of decayed, missing, and filled permanent teeth were not significant.  相似文献   
7.
K W Hayes 《Physical therapy》1992,72(7):515-25; discussion 526-31
This study examined whether physical therapists understand the meaning of measurement error and whether information about measurement error affects their decisions. One of four versions of two physical therapy problems was mailed to 500 randomly selected physical therapists. Therapists were asked to define reliability and error of measurement, to estimate the error of measurement of two assessments, and to make decisions about an intervention based on specific measurements. They were also asked to rate their confidence in those decisions. Problems varied on the presence or absence of measurement information and on the difference between an observed measurement and a criterion measurement against which the observed measurement must be compared to make a decision. The response rate was 62%; respondents represented a typical profile of practicing physical therapists. The therapists understood reliability, but they did not correctly describe the relationship between reliability and error of measurement. Their estimates of the error of measurement of the two assessments were reasonable for only one procedure. The presence or absence of measurement information and difference between observed and criterion measurements affected their confidence, albeit inappropriately, in only one problem. Confidence was not affected by the therapists' level of experience, type of reading, formal study, or degree earned. Therapists responded to the two problems differently. The problems involved different measures, roles, utilities, and structures. The process of decision making does not generalize to all decision types. Measurement principles and strategies of use in decision making must be emphasized in physical therapy curricula so that physical therapists can consider the quality of their assessment data in making clinical decisions.  相似文献   
8.
9.
10.
Nine patients have undergone single-stage radical cystectomy and ileal conduit urinary diversion two to fifty-one months after coronary artery bypass procedures. Two patients presenting with intractable angina at the time their malignant disease was being evaluated required bypass surgery before cystectomy could be undertaken. No significant cardiac morbidity occurred postoperatively, and all remain alive without evidence of malignant disease.  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