全文获取类型
收费全文 | 1372篇 |
免费 | 93篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 51篇 |
妇产科学 | 53篇 |
基础医学 | 176篇 |
口腔科学 | 15篇 |
临床医学 | 206篇 |
内科学 | 228篇 |
皮肤病学 | 12篇 |
神经病学 | 142篇 |
特种医学 | 36篇 |
外科学 | 98篇 |
综合类 | 23篇 |
预防医学 | 207篇 |
眼科学 | 35篇 |
药学 | 114篇 |
中国医学 | 2篇 |
肿瘤学 | 53篇 |
出版年
2024年 | 3篇 |
2023年 | 5篇 |
2022年 | 17篇 |
2021年 | 42篇 |
2020年 | 24篇 |
2019年 | 38篇 |
2018年 | 39篇 |
2017年 | 32篇 |
2016年 | 35篇 |
2015年 | 31篇 |
2014年 | 37篇 |
2013年 | 63篇 |
2012年 | 109篇 |
2011年 | 130篇 |
2010年 | 68篇 |
2009年 | 39篇 |
2008年 | 88篇 |
2007年 | 111篇 |
2006年 | 109篇 |
2005年 | 108篇 |
2004年 | 96篇 |
2003年 | 89篇 |
2002年 | 76篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 9篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1969年 | 2篇 |
排序方式: 共有1466条查询结果,搜索用时 15 毫秒
101.
The internal ribosomal entry site (IRES) RNA of bovine viral diarrhea virus (BVDV) has been implicated in virus propagation. To gain insight into the structure and potential function of the BVDV IRES RNA, we collected and aligned 663 of its sequences. Compensatory Watson-Crick and wobble G·U pairs were investigated to establish phylogenetically supported secondary structures for each of the BVDV IRES RNA sequences. The extensively folded BVDV IRES RNAs were composed of helices 2, 3 and 4. Helix 2 consisted of five helical sections. Helix 3 contained sections 3a to 3j as well as six helical insertions 3.1-3.6. Sections 3a and 3b together with helices 3.6 and 4 formed an RNA pseudoknot. Two highly variable regions corresponded to hairpins 3j and 3.4. Three-dimensional modeling of the BVDV-1b strain Osloss IRES RNA predicted an elongated structure with approximate dimensions of 170 ? by 65 ? by 90 ?. The model of the IRES RNA-ribosome complex suggested proximity between helix 2 of the BVDV IRES and ribosomal proteins S5 and S25. 相似文献
102.
103.
Stins JF Roelofs K Villan J Kooijman K Hagenaars MA Beek PJ 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2011,212(4):603-611
Facial expressions are potent social cues that can induce behavioral dispositions, such as approach–avoidance tendencies.
We studied these tendencies by asking participants to make whole-body forward (approach) or backward (avoidance) steps on
a force plate in response to the valence of social cues (happy or angry faces) under affect-congruent and incongruent mappings.
Posturographic parameters of the steps related to automatic stimulus evaluation, step initiation (reaction time), and step
execution were determined and analyzed as a function of stimulus valence and stimulus–response mapping. The main result was
that participants needed more time to initiate a forward step towards an angry face than towards a smiling face (which is
evidence of a congruency effect), but with backward steps, this difference failed to reach significance. We also found a reduction
in spontaneous body sway prior to the step with the incongruent mapping. The results provide a crucial empirical link between
theories of socially induced action tendencies and theories of postural control and suggest a motoric basis for socially guided
motivated behavior. 相似文献
104.
105.
Steven R. Erickson PharmD. Sally Guthrie PharmD. Michelle VanEtten‐Lee Ph.D. Joseph Himle Ph.D. Jody Hoffman Ph.D. Susana F. Santos PharmD. Amy S. Janeck Ph.D. Kara Zivin Ph.D. James L. Abelson M.D. 《Depression and anxiety》2009,26(12):1165-1171
Background: This study examined associations between anxiety and work‐related outcomes in an anxiety disorders clinic population, examining both pretreatment links and the impact of anxiety change over 12 weeks of treatment on work outcomes. Four validated instruments were used to also allow examination of their psychometric properties, with the goal of improving measurement of work‐related quality of life in this population. Methods: Newly enrolled adult patients seeking treatment in a university‐based anxiety clinic were administered four work performance measures: Work Limitations Questionnaire (WLQ), Work Productivity and Activity Impairment Questionnaire (WPAI), Endicott Work Productivity Scale (EWPS), and Functional Status Questionnaire Work Performance Scale (WPS). Anxiety severity was determined using the Beck Anxiety Inventory (BAI). The Clinical Global Impressions, Global Improvement Scale (CGI‐I) was completed by patients to evaluate symptom change at a 12‐week follow‐up. Two severity groups (minimal/mild vs. moderate/severe, based on baseline BAI score) were compared to each other on work measures. Results: Eighty‐one patients provided complete baseline data. Anxiety severity groups did not differ in job type, time on job, job satisfaction, or job choice. Patients with greater anxiety generally showed lower work performance on all instruments. Job advancement was impaired for the moderate/severe group. The multi‐item performance scales demonstrated better validity and internal consistency. The WLQ and the WPAI detected change with symptom improvement. Conclusion: Level of work performance was generally associated with severity of anxiety. Of the instruments tested, the WLQ and the WPAI questionnaire demonstrated acceptable validity and internal reliability. Depression and Anxiety, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
106.
107.
Hash KM Gottlieb J Harper-Dorton KV Crawley-Woods G Shelek-Furbee K Smith JD Brown R 《Gerontology & geriatrics education》2007,28(1):1-18
This article presents findings from experiences of 67 projects involved in GeroRich, an initiative funded by the John A. Hartford Foundation designed to infuse, enrich and sustain aging content in BSW and MSW curricula. Thematic qualitative analysis was used to uncover themes in answers to open-ended questions contained in End-of-Year 2 project reports. Content areas addressed by open-ended answers were: (1) successes and innovations, and (2) challenges requiring responses. Primary successes and innovations identified were as follows: curriculum enrichment, faculty and student involvement, student-learning activities and community. Challenges to be responded to were identified as lack of faculty involvement, competing demands on faculty and programs, and sustainability of project efforts. Examples of strategies implemented to overcome these obstacles include providing teaching resources, instituting financial and other supports, and developing strategic plans for sustaining content infusion post-funding. Experiences of the GeroRich projects offer practical considerations for other social work programs that accept the challenge of attracting and preparing students to work with the increasing population of older adults. 相似文献
108.
Adherence to Antiretroviral Therapy Assessed by Unannounced Pill Counts Conducted by Telephone 下载免费PDF全文
Kalichman SC Amaral CM Stearns H White D Flanagan J Pope H Cherry C Cain D Eaton L Kalichman MO 《Journal of general internal medicine》2007,22(7):1003-1006
BACKGROUND: Unannounced pill counts conducted in patients' homes is a valid objective method for monitoring medication adherence that is unfortunately costly and often impractical. Conducting unannounced pill counts by telephone may be a viable alternative for objectively assessing medication adherence. PURPOSE: To test an unannounced pill count assessment of adherence conducted by telephone. METHODS: HIV-positive men and women (N = 77) in Atlanta GA completed an unannounced telephone-based pill count immediately followed by a pill count conducted in an unannounced home visit. RESULTS: A high degree of concordance was observed between phone and home-based number of pills counted (Intraclass correlation, ICC = .997, 95% CI .995-.998, P < .001) and percent of pills taken (ICC = .990, 95% CI .986-.992, P < .001). Concordance between adherence above/below 90% and phone/home counts was 95%, Kappa coefficient = .995. Concordance between pill counts was not influenced by participant education or health literacy and was maintained when the data were censored to remove higher levels of adherence. Analyses of discordant pill counts found the most common source of error resulted from overcounted doses in pillboxes on the telephone. CONCLUSIONS: Unannounced phone-based pill counts offer an economically and logistically feasible objective method for monitoring medication adherence. 相似文献
109.
110.
While it is recommended that judgments regarding the credibility of test performance be based on the results of more than one effort indicator, and recent efforts have been made to improve interpretation of multiple effort test failure, the field currently lacks adequate guidelines for using multiple measures of effort in concert with one another. A total of 103 patients were referred for outpatient neuropsychological evaluation, which included multiple measures of negative response bias embedded in standard test batteries. Using any pairwise failure combination to predict diagnostic classification was superior (sensitivity = 83.8%, specificity = 93.9%, overall hit rate = 90.3%) to using any one test by itself and to using any three-test failure combination. Further, the results were comparable to the results of logistical regression analyses using the embedded indicators as continuous predictors. Given its parsimony and clinical utility, the pairwise failure model is therefore a recommended criterion for identifying non-credible performance; however, there are of course other important contextual factors and influences to consider, which are also discussed. 相似文献