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   724611篇
  免费   46084篇
  国内免费   1846篇
耳鼻咽喉   9942篇
儿科学   23084篇
妇产科学   20976篇
基础医学   101452篇
口腔科学   19844篇
临床医学   59951篇
内科学   147101篇
皮肤病学   15213篇
神经病学   57382篇
特种医学   29036篇
外国民族医学   262篇
外科学   113642篇
综合类   15214篇
一般理论   187篇
预防医学   51631篇
眼科学   16038篇
药学   50763篇
  12篇
中国医学   1427篇
肿瘤学   39384篇
  2018年   7315篇
  2017年   5762篇
  2016年   6194篇
  2015年   7011篇
  2014年   9962篇
  2013年   15338篇
  2012年   20583篇
  2011年   21841篇
  2010年   13229篇
  2009年   12603篇
  2008年   20981篇
  2007年   22047篇
  2006年   22432篇
  2005年   21965篇
  2004年   21065篇
  2003年   20324篇
  2002年   20075篇
  2001年   33106篇
  2000年   33930篇
  1999年   29204篇
  1998年   7995篇
  1997年   7320篇
  1996年   7297篇
  1995年   6764篇
  1994年   6508篇
  1993年   6076篇
  1992年   22659篇
  1991年   21551篇
  1990年   21118篇
  1989年   20317篇
  1988年   18802篇
  1987年   18567篇
  1986年   17763篇
  1985年   16825篇
  1984年   12639篇
  1983年   10794篇
  1982年   6500篇
  1979年   11573篇
  1978年   8156篇
  1977年   6842篇
  1976年   6500篇
  1975年   7171篇
  1974年   8540篇
  1973年   8142篇
  1972年   7750篇
  1971年   7123篇
  1970年   6848篇
  1969年   6384篇
  1968年   6130篇
  1967年   5662篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.

Background

Identification of the risk of falls is important among older inpatients. This study aims to examine performance criteria (i.e.; sensitivity, specificity, positive predictive value, negative predictive value and accuracy) for fall prediction resulting from a nurse assessment and an artificial neural networks (ANNs) analysis in older inpatients hospitalized in acute care medical wards.

Methods

A total of 848 older inpatients (mean age, 83.0±7.2 years; 41.8% female) admitted to acute care medical wards in Angers University hospital (France) were included in this study using an observational prospective cohort design. Within 24 hours after admission of older inpatients, nurses performed a bedside clinical assessment. Participants were separated into non-fallers and fallers (i.e.; ≥1 fall during hospitalization stay). The analysis was conducted using three feed forward ANNs (multilayer perceptron [MLP], averaged neural network, and neuroevolution of augmenting topologies [NEAT]).

Results

Seventy-three (8.6%) participants fell at least once during their hospital stay. ANNs showed a high specificity, regardless of which ANN was used, and the highest value reported was with MLP (99.8%). In contrast, sensitivity was lower, with values ranging between 98.4 to 14.8%. MLP had the highest accuracy (99.7).

Conclusions

Performance criteria for fall prediction resulting from a bedside nursing assessment and an ANNs analysis was associated with a high specificity but a low sensitivity, suggesting that this combined approach should be used more as a diagnostic test than a screening test when considering older inpatients in acute care medical ward.
  相似文献   
72.
73.
Dominicans are the largest migrant community in Puerto Rico, yet understudied. We compared risk factors and health conditions of Dominicans versus Puerto Ricans (PRs). Cross-sectional survey of Dominicans (n?=?55) and PRs (n?=?310) aged 30–75 years, assessed with validated questionnaires and standardized anthropometric measurements. Significantly, more Dominicans than PRs had attained <8th grade education (37.7 vs. 8.0%), reported household income ≤$10,000 (76.1 vs. 56.9%), lacked health insurance (19.6 vs. 5.5%), and reported food insecurity (24.5 vs. 12.1%). They spent fewer hours/day watching television (2.9 vs. 3.8), and were less likely to smoke (7.6 vs. 19.6%). Medically-diagnosed depression was lower among Dominicans than PRs (9.6 vs. 23.0%); questionnaire-based high depressive symptomatology was similar (47.9 vs. 52.8%). Dominicans living in Puerto Rico had more socioeconomic risk factors but healthier lifestyle behaviors and lower prevalence of medically-diagnosed depression than PRs. Tailored approaches are needed to ameliorate disparities in each ethnic group.  相似文献   
74.
75.
76.
77.
Clinical studies of incidences of the number of canals in human teeth should correlate with the percentages obtained in laboratory samples. In this study the incidence of two canals in the mandibular incisors was compared with figures obtained from in vitro extracted teeth, as well as from one clinical study. A very low percentage was obtained from the examination of clinical records, and this could be due to racial differences in the samples examined.  相似文献   
78.
A panoramic radiograph obtained during orthodontic treatment revealed an intracoronal radiolucency within an unerupted permanent second molar. This unusual entity was successfully treated by surgical and endodontic intervention, followed by restorative and orthodontic treatment. These treatments enabled the tooth to maintain pulpal vitality, erupt, complete root formation, and function. This report will review the proposed etiologies for this condition, discuss the need for surgical intervention, and present the details of the case.  相似文献   
79.
The Authors present the results of a clinical study concerning 30 IDDM patients and 24 healthy subjects to evaluate periodontal disease. The results show a higher incidence of PI, PD and BTI in diabetic patients.  相似文献   
80.
The presence of bacteria in periapical lesions of teeth with necrotic pulp has been demonstrated by microbiological sampling of periapical lesions during endodontic surgery. The purpose of this study was to confirm the presence of Bacteroides intermedius in a periapical granuloma using an indirect immunofluorescence technique. Histologic sections of a periapical granuloma were incubated with a rabbit antiserum to B. intermedius. After incubation with secondary antibody (fluorescein-conjugated goat anti-rabbit IgG), an intense fluorescent staining was observed in areas of the tissue sections. Control tissue sections that were incubated without the antibody remained unstained. The results obtained with the indirect immunofluorescence technique supported our cultural findings that microorganisms, e.g. B. intermedius, were present in the tissue of the periapical granuloma.  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