全文获取类型
收费全文 | 49371篇 |
免费 | 3823篇 |
国内免费 | 108篇 |
专业分类
耳鼻咽喉 | 510篇 |
儿科学 | 1703篇 |
妇产科学 | 1314篇 |
基础医学 | 6209篇 |
口腔科学 | 651篇 |
临床医学 | 7667篇 |
内科学 | 9187篇 |
皮肤病学 | 555篇 |
神经病学 | 5003篇 |
特种医学 | 1197篇 |
外国民族医学 | 1篇 |
外科学 | 4765篇 |
综合类 | 556篇 |
一般理论 | 60篇 |
预防医学 | 6613篇 |
眼科学 | 560篇 |
药学 | 3014篇 |
中国医学 | 44篇 |
肿瘤学 | 3693篇 |
出版年
2023年 | 329篇 |
2022年 | 498篇 |
2021年 | 962篇 |
2020年 | 713篇 |
2019年 | 1078篇 |
2018年 | 1255篇 |
2017年 | 956篇 |
2016年 | 1009篇 |
2015年 | 1140篇 |
2014年 | 1594篇 |
2013年 | 2455篇 |
2012年 | 3549篇 |
2011年 | 3707篇 |
2010年 | 2001篇 |
2009年 | 1819篇 |
2008年 | 3321篇 |
2007年 | 3295篇 |
2006年 | 3195篇 |
2005年 | 3151篇 |
2004年 | 2860篇 |
2003年 | 2544篇 |
2002年 | 2411篇 |
2001年 | 542篇 |
2000年 | 566篇 |
1999年 | 572篇 |
1998年 | 565篇 |
1997年 | 458篇 |
1996年 | 394篇 |
1995年 | 311篇 |
1994年 | 303篇 |
1993年 | 298篇 |
1992年 | 376篇 |
1991年 | 383篇 |
1990年 | 334篇 |
1989年 | 327篇 |
1988年 | 287篇 |
1987年 | 297篇 |
1986年 | 320篇 |
1985年 | 303篇 |
1984年 | 261篇 |
1983年 | 223篇 |
1982年 | 193篇 |
1981年 | 186篇 |
1980年 | 160篇 |
1979年 | 210篇 |
1978年 | 133篇 |
1977年 | 127篇 |
1975年 | 118篇 |
1974年 | 117篇 |
1973年 | 109篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
Heidi J Kalkwarf John A Shepherd Didier Hans Elena Gonzalez Rodriguez Joseph M Kindler Joan M Lappe Sharon Oberfield Karen K Winer Babette S Zemel 《Journal of bone and mineral research》2022,37(4):776-785
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.
Fluid role boundaries: exploring the contribution of the advanced nurse practitioner to multi‐professional palliative care
下载免费PDF全文
![点击此处可从《Journal of clinical nursing》网站下载免费的PDF全文](/ch/ext_images/free.gif)
25.
James I. Geller MD Joseph G. Pressey MD Malcolm A. Smith MD Rachel A. Kudgus PhD Mariana Cajaiba MD Joel M. Reid PhD David Hall PhD Donald A. Barkauskas PhD Stephen D. Voss MD Steve Y. Cho MD Stacey L. Berg MD Jeffrey S. Dome MD PhD Elizabeth Fox MD Brenda J. Weigel MD 《Cancer》2020,126(24):5303-5310
26.
27.
Reem Haj-Ali BDS DDS MS ; Mary Walker DDS PhD ; Karen Williams PhD ; Yong Wang PhD ; Paulette Spencer DDS PhD 《Journal of prosthodontics》2006,15(2):82-88
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
28.
Karen Bogenschneider 《Family relations》2006,55(1):16-28
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
29.
30.