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   3321246篇
  免费   233785篇
  国内免费   5820篇
耳鼻咽喉   47680篇
儿科学   105336篇
妇产科学   91760篇
基础医学   482495篇
口腔科学   94820篇
临床医学   295846篇
内科学   637606篇
皮肤病学   74435篇
神经病学   263491篇
特种医学   126661篇
外国民族医学   894篇
外科学   503681篇
综合类   71253篇
现状与发展   16篇
一般理论   1215篇
预防医学   250742篇
眼科学   78867篇
药学   248555篇
  15篇
中国医学   6847篇
肿瘤学   178636篇
  2018年   35341篇
  2017年   27088篇
  2016年   30415篇
  2015年   33811篇
  2014年   47581篇
  2013年   72427篇
  2012年   98102篇
  2011年   104574篇
  2010年   62098篇
  2009年   58658篇
  2008年   98950篇
  2007年   106346篇
  2006年   106957篇
  2005年   103977篇
  2004年   99816篇
  2003年   96645篇
  2002年   93970篇
  2001年   149752篇
  2000年   153893篇
  1999年   129612篇
  1998年   37370篇
  1997年   33006篇
  1996年   32599篇
  1995年   30904篇
  1994年   28604篇
  1993年   26952篇
  1992年   100623篇
  1991年   98193篇
  1990年   96047篇
  1989年   93023篇
  1988年   86019篇
  1987年   84596篇
  1986年   79968篇
  1985年   76738篇
  1984年   57209篇
  1983年   48771篇
  1982年   29225篇
  1981年   26371篇
  1979年   53565篇
  1978年   38406篇
  1977年   32592篇
  1976年   30563篇
  1975年   33703篇
  1974年   40215篇
  1973年   38628篇
  1972年   36531篇
  1971年   34478篇
  1970年   32203篇
  1969年   30781篇
  1968年   28466篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
71.
72.
73.
74.
In the USA, the Black Church is among the most important institutions in the Black community, offering numerous spiritual, social and health benefits. Yet, the presence of homonegativity in many Black Churches may mitigate those effects for gay Black youth. This research examines the role of the Church in the lives of gay and bisexual Black youth to understand how they reconcile any tension between their religious and sexual identities. Through interviews with pastors of Black churches (n = 21) and young Black men who have sex with men (n = 30), we explored homonegativity and young men’s experiences within the Black Church. Findings reveal that despite the prevalence of homonegativity within Black churches, religious involvement remains important for young men and many remain involved in non-affirming churches. The importance of the Church for young men stems from their significant involvement as youth and the integration of religion, family and community. Young men may not be able to leave their religious homes as readily as other gay youth given the cultural relevance of the Church. As a result, young men made attempts to conceal their sexuality in church to avoid shame and gossip and find opportunities to balance their sexuality and religiosity.  相似文献   
75.
76.
Objectives: The steeling effect suggests that early-life adversity can have a beneficial impact later in life. However, little is known about its underlying mechanisms and long-term outcomes . The study aimed to examine the role of early-life adversity (ELA) on successful aging, and whether this relationship can be explained by mental and physical health.

Method: Socio-demographics, early-life adversity (ELA), individual quality of life (iQoL), and mental and physical health of 270 individuals (Mage = 66.82 years, 71.5% female) were assessed. Polynomial regressions and mediation analyses were conducted.

Results: Significant inverse U-shaped associations were found between ELA and iQoL (β = ?.59, p = .005) and between ELA and mental health (β = ?.64, p = .002), but not between ELA and physical health. Furthermore, mental health significantly mediated the relationship between ELA and iQoL (b = ?.84, BCa CI [?1.66, ?.27]).

Conclusion: Highest level of individual quality of life (i.e. successful aging) was related to a moderate amount of ELA. Additionally, mental health significantly mediated this relationship. These findings suggest that some amount of ELA could be beneficial for successful aging. Resource-focused interventions are needed to improve health and promote successful aging for an underdetected, at-risk subgroup with low early-life adversity.  相似文献   

77.

Background

Obesity is a risk factor for acetabular component malposition when total hip arthroplasty is performed with manual techniques. The utility of imageless navigation in obese patients remains unknown. This study compared the accuracy and precision of imageless navigation for component orientation between obese and nonobese patients.

Methods

A total of 459 total hip arthroplasties performed for osteoarthritis using imageless navigation were reviewed from a single surgeon’s institutional review board–approved database. Einzel-Bild-Roentgen Analyse determined component orientation on 6-week postoperative anteroposterior radiographs. Mean orientation error (accuracy) and precision were compared between obese (body mass index ≥ 30 kg/m2) and nonobese patients. Regression analysis evaluated the influence of obesity on component position.

Results

The difference in mean inclination and anteversion between obese and nonobese groups was 1.1° (43.0° ± 3.5°; range, 35.8°-57.8° vs 41.9° ± 4.4°; range, 33.0°-57.1° and 24.9° ± 6.3°; range, 14.2°-44.3° vs 23.8° ± 6.6°; range, 7.0°-38.6°, respectively). Inclination precision was better for nonobese patients. No difference in inclination accuracy or anteversion accuracy or precision was detected between groups. And 83% of components were placed within the target range. There was no relationship between obesity (dichotomized) and component placement outside the target ranges for inclination, anteversion, or both. As a continuous variable, increased body mass index correlated with higher odds of inclination outside the target zone (odds ratio, 1.06; P = .001).

Conclusion

Using imageless navigation, inclination orientation was less precise for obese patients, but the observed difference is likely not clinically relevant. Accurate superficial registration of landmarks in obese patients is achievable, and the use of imageless navigation similarly improves acetabular component positioning in obese and nonobese patients.

Level of Evidence

Therapeutic Level IV.  相似文献   
78.

Objective

To systematically review literature on uptake and timeliness of diphtheria-tetanus-pertussis, measles-mumps-rubella, and/or polio-containing vaccines in infants who were born preterm, with a low birth weight, and/or with chronic health conditions that were diagnosed within the first 6?months of life.

Methods

Using a standardized search strategy developed by a medical librarian, records were extracted from MEDLINE, Embase, Database of Abstracts of Reviews of Effects, and CINAHL up to May 8, 2018.

Results

Out of the 1997 records that were screened, we identified 21 studies that met inclusion criteria. Eleven studies assessed vaccine coverage and/or timeliness in preterm infants, 6 in low birth weight infants, and 7 in children with chronic health conditions. Estimates of coverage in these populations were highly variable, ranging from 40% to 100% across the vaccines and population groups.

Conclusions

There is a lack of studies reporting coverage and timeliness of routine immunizations in special populations of children.

Policy implications

Our review suggests a need for improved surveillance of immunization status in special populations of infants, as well as a need for standardization of reporting practices.  相似文献   
79.

Introduction

Physician communication impacts patient outcomes. However, communication skills, especially around difficult conversations, remain suboptimal, and there is no clear way to determine the validity of entrustment decisions. The aims of this study were to 1) describe the development of a simulation-based mastery learning (SBML) curriculum for breaking bad news (BBN) conversation skills and 2) set a defensible minimum passing standard (MPS) to ensure uniform skill acquisition among learners.

Innovation

An SBML BBN curriculum was developed for fourth-year medical students. An assessment tool was created to evaluate the acquisition of skills involved in a BBN conversation. Pilot testing was completed to confirm improvement in skill acquisition and set the MPS.

Outcomes

A BBN assessment tool containing a 15-item checklist and six scaled items was developed. Students' checklist performance improved significantly at post-test compared to baseline (mean 65.33%, SD = 12.09% vs mean 88.67%, SD = 9.45%, P < 0.001). Students were also significantly more likely to have at least a score of 4 (on a five-point scale) for the six scaled questions at post-test. The MPS was set at 80%, requiring a score of 12 items on the checklist and at least 4 of 5 for each scaled item. Using the MPS, 30% of students would require additional training after post-testing.

Comments

We developed a SBML curriculum with a comprehensive assessment of BBN skills and a defensible competency standard. Future efforts will expand the mastery model to larger cohorts and assess the impact of rigorous education on patient care outcomes.  相似文献   
80.
Purpose of the study: the aim of this study was to synthesize PFC fNIRS outcomes on the effects of cognitive tasks compared to resting/baseline tasks in healthy adults from studies utilizing a pre/post design.

Material and methods: original research studies were searched from seven databases (MEDLINE, EMBASE, CENTRAL, CINAHL, SCOPUS, PEDro and PubMed). Subsequently, two independent reviewers screened the titles and abstracts followed by full-text reviews to assess the studies' eligibility.

Results: eleven studies met the inclusion criteria and had data abstracted and quality assessed. Methodology varied considerably and yet cognitive tasks resulted in the ΔO2Hb increasing in 8 of the 11 and ΔHHb decreasing in 8 of 8 studies that reported this outcome. The cognitive tasks from 10 of the 11 studies were classified as “Working Memory” and “Verbal Fluency Tasks”.

Conclusions: although, the data comparison was challenging provided the heterogeneity in methodology, the results across studies were similar.  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