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   2072598篇
  免费   154047篇
  国内免费   3913篇
耳鼻咽喉   27397篇
儿科学   69361篇
妇产科学   58303篇
基础医学   305052篇
口腔科学   58380篇
临床医学   192043篇
内科学   400424篇
皮肤病学   45784篇
神经病学   166088篇
特种医学   78103篇
外国民族医学   554篇
外科学   299656篇
综合类   46241篇
现状与发展   3篇
一般理论   922篇
预防医学   169184篇
眼科学   47186篇
药学   150944篇
  44篇
中国医学   3795篇
肿瘤学   111094篇
  2018年   21937篇
  2017年   16867篇
  2016年   18816篇
  2015年   21514篇
  2014年   29693篇
  2013年   45559篇
  2012年   60999篇
  2011年   65186篇
  2010年   38243篇
  2009年   36411篇
  2008年   61043篇
  2007年   65175篇
  2006年   65134篇
  2005年   63252篇
  2004年   61192篇
  2003年   58806篇
  2002年   56903篇
  2001年   91993篇
  2000年   94158篇
  1999年   79268篇
  1998年   22537篇
  1997年   20467篇
  1996年   20763篇
  1995年   19815篇
  1994年   18432篇
  1993年   17213篇
  1992年   63522篇
  1991年   62372篇
  1990年   61054篇
  1989年   58977篇
  1988年   54141篇
  1987年   53801篇
  1986年   50848篇
  1985年   48548篇
  1984年   36818篇
  1983年   31724篇
  1982年   18980篇
  1981年   17182篇
  1979年   34640篇
  1978年   25322篇
  1977年   21251篇
  1976年   19940篇
  1975年   21259篇
  1974年   25836篇
  1973年   25186篇
  1972年   23652篇
  1971年   22008篇
  1970年   20642篇
  1969年   19364篇
  1968年   18008篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Abstract

The study examines Parental Feeding Practices (PFP) in relation to adherence to the Mediterranean Diet (MD) and children’s weight status. It’s a cross-sectional study of 402 parents (68.4% mothers), with children aged 2–12 years. Parents completed the Comprehensive Parental Feeding Questionnaire and the Mediterranean Diet Quality Index for children and adolescents (KIDMED), evaluating children’s adherence to the MD. Logistic regression showed that in children aged 2–<6 years, “emotion regulation/food as reward” and “pressure” decrease MD adherence (OR?=?0.186, p?<?0.0001 and OR?=?0.496, p?=?0.004), and “monitoring” decrease excess body weight (OR?=?0.284, p?=?0.009). In older children (6–12 years), “healthy eating guidance” and “monitoring” increase MD adherence (OR?=?3.262, p?=?0.001 and OR?=?3.147, p?<?0.0001), “child control” decreases MD adherence (OR?=?0.587, p?=?0.049), “pressure” decrease excess body weight (OR?=?0.495, p?<?0.0001) and “restriction” increase excess body weight (OR?=?1.784, p?=?0.015). “Healthy eating guidance” and “monitoring” seem to be the best PFP employed, in terms of children’s MD adherence and weight status.  相似文献   
43.
BACKGROUND AND PURPOSE:Little is known about microstructural development of cerebellar white matter in vivo. This study aimed to investigate developmental changes of the cerebellar peduncles in second- and third-trimester healthy fetuses using motion-corrected DTI and tractography.MATERIALS AND METHODS:3T data of 81 healthy fetuses were reviewed. Structural imaging consisted of multiplanar T2-single-shot sequences; DTI consisted of a series of 12-direction diffusion. A robust motion-tracked section-to-volume registration algorithm reconstructed images. ROI-based deterministic tractography was performed using anatomic landmarks described in postnatal tractography. Asymmetry was evaluated qualitatively with a perceived difference of >25% between sides. Linear regression evaluated gestational age as a predictor of tract volume, ADC, and fractional anisotropy.RESULTS:Twenty-four cases were excluded due to low-quality reconstructions. Fifty-eight fetuses with a median gestational age of 30.6 weeks (interquartile range, 7 weeks) were analyzed. The superior cerebellar peduncle was identified in 39 subjects (69%), and it was symmetric in 15 (38%). The middle cerebellar peduncle was identified in all subjects and appeared symmetric; in 13 subjects (22%), two distinct subcomponents were identified. The inferior cerebellar peduncle was not found in any subject. There was a significant increase in volume for the superior cerebellar peduncle and middle cerebellar peduncle (both, P < .05), an increase in fractional anisotropy (both, P < .001), and a decrease in ADC (both, P < .001) with gestational age. The middle cerebellar peduncle had higher volume (P < .001) and fractional anisotropy (P = .002) and lower ADC (P < .001) than the superior cerebellar peduncle after controlling for gestational age.CONCLUSIONS:A robust motion-tracked section-to-volume registration algorithm enabled deterministic tractography of the superior cerebellar peduncle and middle cerebellar peduncle in vivo and allowed characterization of developmental changes.

In the second half of pregnancy, the cerebellum is growing rapidly and is extremely vulnerable.1 Despite the increasingly recognized association of antenatal and perinatal cerebellar injury with adverse motor and neurologic outcomes later in life,2-5 little is known about normal cerebellar developmental in the later part of gestation, in particular with regard to changes in microstructure. In fact, most existing fetal MR imaging data addresses primarily changes in cerebellar volume with gestational age (GA) or changes in volume and their association with specific diseases such as congenital heart disease.6-8In vivo evaluation of cerebellar microstructure using fetal MR imaging has been limited by the technical challenges related to imaging the gravid abdomen, particularly patient motion. However, data from ex vivo MR imaging studies are promising. For instance, Takahashi et al9,10 performed high-resolution ex vivo DTI of fetal specimens and demonstrated the feasibility of using tractography to outline the cerebellar peduncles prenatally. Even though tractography of the cerebellar peduncles has been sporadically reported in vivo in technical articles or general review articles on fetal DTI,11 the GA-related microstructural changes that occur in the cerebellar peduncles in the second half of pregnancy remain largely unexplored.Recent advances in hardware and software have improved fetal MR imaging substantially. The use of 3T magnets, which have been shown to be safe, results in improvement of the SNR and spatial resolution, which is advantageous to image the small structures of the fetal brain.12,13 In addition, postprocessing algorithms that enable reconstruction of motion-corrected fetal DTI data are increasingly available and have been used by several groups to characterize the development of the supratentorial white matter tracts in vivo.14-16 We hypothesize that fetal DTI performed at 3T and processed with a robust section-to-volume motion-correction and registration14 algorithm will enable tractography of the cerebellar peduncles in fetuses in the second and third trimesters of pregnancy. We aimed to characterize fetal cerebellar tract microstructure and to investigate tract-specific developmental changes.  相似文献   
44.
45.
Abstract

Introduction: Student-staff partnerships as a concept to improve medical education have received a growing amount of attention. Such partnerships are collaborations in which students and teachers seek to improve education by each adding their unique contribution to decision-making and implementation processes. Although previous research has demonstrated that students are favourable to this concept, teachers remain hesitant. The present study investigated teachers’ conceptions of student-staff partnerships and of the prerequisites that are necessary to render such partnerships successful and enhance educational quality.

Method: We conducted semi-structured interviews with 14 course coordinators who lead course design teams and also teach in 4 bachelor health programmes, using Bovill and Bulley’s levels of student participation as sensitising concepts during data analysis.

Results: The results pointed to three different conceptions of student-staff partnerships existing among teachers: Teachers teach and students study; teachers teach and value students’ feedback; and teachers and students co-create. The prerequisites for effective co-creation teachers identified were: Teachers must be open to involve students and create dialogues; students must be motivated and have good communication skills; the organisation must be supportive; and teachers should have the final say.

Conclusion: We conclude that teachers’ conceptions are consistent with Bovill and Bulley’s levels of student participation. Under certain conditions, teachers are willing to co-create and reach the highest levels of student participation.  相似文献   
46.
Abstract

Data on eating disorders in women with PCOS is insufficient. The objective of this case study was to examine the hypothesis that women with PCOS exhibit more impaired eating than healthy women. Women diagnosed with PCOS under the 2003 Rotterdam Diagnostic Criteria (n?=?40) were compared with a healthy control group (n?=?40). The groups also were divided into two as normal body weight and overweight/obese. The Eating Disorders Assessment Questionnaire (EDE-Q) and the Three Factor Eating Questionnaire (TFEQ-R21), were completed by all participants in order to evaluate eating behaviors in addition to eating disorders. Among the overweight/obese group, the average total and subscale scores of the EDE-Q as well as the total and sub-factor scores of the TFEQ-R21 were higher in women with PCOS compared to controls (p?<?.05). However, this statistically significant result was not shown among the women with normal weight (p?>?.05). In comparison to the controls, the PCOS women displayed higher values of the tool scores indicating abnormal restraint eating, body shape concern and weight concern subscale scores (p?<?.05). This result suggests that the evaluation of eating disorders should be added to routine screening and the monitoring of women with PCOS.  相似文献   
47.
Abstract

Objective

Demands for out-of-hours primary care (OOH-PC) services are increasing. Many citizens call because of non-urgent health problems. Nevertheless, the patients’ motives for requesting medical help outside office hours remains an understudied area. This study aimed to examine motives for calling OOH-PC services in various age groups.  相似文献   
48.
ABSTRACT

Purpose

New instrument-based techniques for anterior chamber (AC) cell counting can offer automation and objectivity above clinician assessment. This review aims to identify such instruments and its correlation with clinician estimates.  相似文献   
49.
Abstract

Live discussions on the social media site Twitter or Twitter chats are gaining popularity as powerful tools for engaging a broad audience in an interactive discussion. Medical education, in particular, is experiencing an increase in the use of this modality to support informal learning, as a means to encourage collaboration and share best practices, and as a platform for large-scale mentorship. Despite this growth in popularity, there are limited data to guide medical educators on the fundamentals of organizing a Twitter chat. In this Twelve Tips article, we discuss strategies relevant to potential Twitter chat organizers. We have arranged the tips chronologically, beginning with a discussion of initial considerations when planning and formulating a chat topic and publicizing the chat to potentially interested people and groups, followed by practical considerations while hosting the chat, and finally strategies for evaluating and extending a Twitter chat’s impact.  相似文献   
50.

Background

Spontaneous decolonization of antibiotic-resistant bacteria (ARB) takes time: approximately 25% after 30 days for carbapenem-producing Enterobacteriaceae or extended-spectrum beta-lactamase-producing Enterobacteriaceae. Faecal microbiota transplantation (FMT) has been proposed as a new strategy to promote decolonization in order to reduce the risk of superinfection due to these ARB. This paper discusses the literature on the use of FMT for this indication, and the improvement levers available to promote its efficacy.

Methods

Literature available to date concerning the use of FMT to eradicate ARB was reviewed, and the different factors that may have influenced the efficacy of decolonization were evaluated.

Results

Four axes that could have played major roles in the efficacy of FMT were identified: bowel preparation before FMT; donor; dose; and thermal conditioning of faeces. The positive or negative impact of each on the outcome of FMT is discussed.

Conclusion

Although FMT is very efficient for the eradication of Clostridium difficile, the same ‘recipe’ cannot be used for the eradication of ARB. Working together with expert centres may help to improve the efficacy of FMT for this indication, and enable the reduction of in-hospital isolation precautions.  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