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   38371篇
  免费   2577篇
  国内免费   95篇
耳鼻咽喉   448篇
儿科学   1432篇
妇产科学   944篇
基础医学   4706篇
口腔科学   477篇
临床医学   6415篇
内科学   6590篇
皮肤病学   401篇
神经病学   3717篇
特种医学   795篇
外国民族医学   1篇
外科学   3560篇
综合类   358篇
一般理论   49篇
预防医学   5409篇
眼科学   401篇
药学   2358篇
中国医学   44篇
肿瘤学   2938篇
  2024年   23篇
  2023年   293篇
  2022年   182篇
  2021年   846篇
  2020年   603篇
  2019年   940篇
  2018年   1095篇
  2017年   813篇
  2016年   854篇
  2015年   945篇
  2014年   1328篇
  2013年   2093篇
  2012年   3033篇
  2011年   3216篇
  2010年   1711篇
  2009年   1550篇
  2008年   2784篇
  2007年   2792篇
  2006年   2732篇
  2005年   2685篇
  2004年   2473篇
  2003年   2197篇
  2002年   2109篇
  2001年   237篇
  2000年   202篇
  1999年   269篇
  1998年   436篇
  1997年   338篇
  1996年   260篇
  1995年   209篇
  1994年   216篇
  1993年   196篇
  1992年   118篇
  1991年   113篇
  1990年   87篇
  1989年   97篇
  1988年   89篇
  1987年   76篇
  1986年   82篇
  1985年   78篇
  1984年   96篇
  1983年   75篇
  1982年   85篇
  1981年   97篇
  1980年   69篇
  1979年   40篇
  1978年   30篇
  1977年   36篇
  1976年   21篇
  1975年   23篇
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
21.
ObjectiveClinical specialty societies recommend long-acting reversible contraceptives (LARCs) as first-line contraception for adolescent women. We evaluated whether a combined educational and process improvement intervention enhanced LARC placement in primary care within an integrated health care system.MethodsThe intervention included journal clubs, live continuing education, point-of-care guidelines, and new patient materials. We conducted a retrospective cohort study across 3 time periods: baseline (January 2013?September 2015), early implementation (October 2015–March 2016), and full implementation (April 2016–June 2017). The primary outcome was the proportion of LARCs placed by primary care clinicians among women aged 13 to 18 years compared with gynecology clinicians.ResultsKaiser Foundation Health Plan of Colorado cared for approximately 20,000 women aged 13 to 18 years in each calendar quarter between 2013 and 2017. Overall, LARC placement increased from 7.0 per 1000 members per quarter at baseline to 13.0 per 1000 during the full intervention. Primary care clinicians placed 6.2% of all LARCs in 2013, increasing to 32.1% by 2017 (P < .001), including 45.5% of contraceptive implants. Clinicians who attended educational sessions were more likely to adopt LARCs than those who did not (17.9% vs 6.4% respectively, P = .009). Neither overall LARC placement rates (relative risk, 1.9; 95% confidence interval, 0.7?5.6) nor contraceptive implant rates (relative risk, 3.0; 95% confidence interval, 0.9?9.8) increased significantly in clinicians who attended educational activities.ConclusionsThis multimodal intervention was associated with increased LARC placement for adolescent women in primary care. The combination of education and process improvement is a promising strategy to promote clinician behavior change.  相似文献   
22.
23.
Trabecular bone score (TBS) is used for fracture prediction in adults, but its utility in children is limited by absence of appropriate reference values. We aimed to develop reference ranges for TBS by age, sex, and population ancestry for youth ages 5 to 20 years. We also investigated the association between height, body mass index (BMI), and TBS, agreement between TBS and lumbar spine areal bone mineral density (aBMD) and bone mineral apparent density (BMAD) Z-scores, tracking of TBS Z-scores over time, and precision of TBS measurements. We performed secondary analysis of spine dual-energy X-ray absorptiometry (DXA) scans from the Bone Mineral Density in Childhood Study (BMDCS), a mixed longitudinal cohort of healthy children (n = 2014) evaluated at five US centers. TBS was derived using a dedicated TBS algorithm accounting for tissue thickness rather than BMI. TBS increased only during ages corresponding to pubertal development with an earlier increase in females than males. There were no differences in TBS between African Americans and non-African Americans. We provide sex-specific TBS reference ranges and LMS values for calculation of TBS Z-scores by age and means and SD for calculation of Z-scores by pubertal stage. TBS Z-scores were positively associated with height Z-scores at some ages. TBS Z-scores explained only 27% and 17% of the variance of spine aBMD and BMAD Z-scores. Tracking of TBS Z-scores over 6 years was lower (r = 0.47) than for aBMD or BMAD Z-scores (r = 0.74 to 0.79), and precision error of TBS (2.87%) was greater than for aBMD (0.85%) and BMAD (1.22%). In sum, TBS Z-scores provide information distinct from spine aBMD and BMAD Z-scores. Our robust reference ranges for TBS in a well-characterized pediatric cohort and precision error estimates provide essential tools for clinical assessment using TBS and determination of its value in predicting bone fragility in childhood and adolescence. © 2022 American Society for Bone and Mineral Research (ASBMR).  相似文献   
24.
25.
26.
27.
28.
PURPOSE: The purpose of this study was to compare the dentin/adhesive interfacial characteristics when bonding to noncarious as well as caries-affected dentin. MATERIALS AND METHODS: Seven extracted, unerupted, third molars were sectioned into halves. Artificial caries was created on one-half of each tooth, leaving the other half as a control. Dentin surfaces were treated with UNO adhesive according to the manufacturer's instructions for the wet-bonding technique and under environmental conditions present in the oral cavity. Dentin/adhesive interface sections of each half-tooth were stained with Goldner's trichrome, a classic bone stain, and examined using light microscopy. The width of exposed collagen was measured directly from photomicrographs, and adhesive penetration was analyzed qualitatively. RESULTS: The degree and extent to which the adhesive encapsulated the demineralized dentin matrix were reflected in the color difference in the stained sections with the noncarious dentin sections showing a degree of collagen encapsulation superior to that of the caries-affected dentin sections. The overall mean widths of exposed collagen were significantly (p < or = .05) greater at the caries-affected dentin/adhesive interface, 8.6 (1.7) microm, as compared with those at the noncarious dentin/adhesive interface, 6.0 (1.5) microm. CONCLUSIONS: The morphologic characteristics of the caries-affected dentin/interface suggest an increase in the exposed collagen zone and a decrease in the quality of the adhesive infiltration when compared with noncarious dentin. The evidence suggests that dentin substrate characteristics have a significant effect on the dentin/adhesive interface structure.  相似文献   
29.
Abstract: As newcomers on college campuses, family policy courses have the potential to benefit policymaking, fill a void in undergraduate and graduate education, strengthen families, and prepare students for lifelong political engagement during a pivotal period in their development. Yet, family policy has proven a challenging course to teach. Family policy is an esoteric concept, which makes courses difficult to distinguish from other policy courses. The content of a family policy course is fluid and inherently value laden. This paper proposes course content and teaching techniques to transform these challenges into learning opportunities. The author discusses similarities and differences in teaching undergraduate and graduate courses and recommends cross‐university dialogue and resource exchange to improve the teaching of family policy in college classrooms.  相似文献   
30.
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