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   208776篇
  免费   2842篇
  国内免费   188篇
耳鼻咽喉   1502篇
儿科学   7393篇
妇产科学   3644篇
基础医学   22797篇
口腔科学   2320篇
临床医学   14983篇
内科学   37147篇
皮肤病学   1545篇
神经病学   19870篇
特种医学   10358篇
外科学   33448篇
综合类   2468篇
一般理论   15篇
预防医学   19656篇
眼科学   3460篇
药学   11815篇
中国医学   645篇
肿瘤学   18740篇
  2021年   381篇
  2020年   321篇
  2019年   531篇
  2018年   22440篇
  2017年   17764篇
  2016年   20012篇
  2015年   1578篇
  2014年   1616篇
  2013年   1981篇
  2012年   8641篇
  2011年   22717篇
  2010年   19974篇
  2009年   12623篇
  2008年   21351篇
  2007年   23573篇
  2006年   2483篇
  2005年   4170篇
  2004年   5240篇
  2003年   6141篇
  2002年   4378篇
  2001年   613篇
  2000年   692篇
  1999年   567篇
  1998年   711篇
  1997年   626篇
  1996年   457篇
  1995年   440篇
  1994年   385篇
  1993年   319篇
  1992年   254篇
  1991年   293篇
  1990年   304篇
  1989年   250篇
  1988年   232篇
  1987年   180篇
  1986年   157篇
  1985年   200篇
  1984年   211篇
  1983年   196篇
  1982年   228篇
  1981年   178篇
  1980年   172篇
  1977年   154篇
  1938年   179篇
  1933年   183篇
  1932年   230篇
  1931年   167篇
  1930年   210篇
  1928年   163篇
  1926年   164篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
21.
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   
22.
The impact of primary hand osteoarthritis (HOA) on bone mass, microstructure, and biomechanics in the affected skeletal regions is largely unknown. HOA patients and healthy controls (HCs) underwent high-resolution peripheral quantitative computed tomography (HR-pQCT). We measured total, trabecular, and cortical volumetric bone mineral densities (vBMDs), microstructural attributes, and performed micro–finite element analysis for bone strength. Failure load and scaled multivariate outcome matrices from distal radius and second metacarpal (MCP2) head measurements were analyzed using multiple linear regression adjusting for age, sex, and functional status and reported as adjusted Z-score differences for total and direct effects. A total of 105 subjects were included (76 HC: 46 women, 30 men; 29 HOA: 23 women, six men). After adjustment, HOA was associated with significant changes in the multivariate outcome matrix from the MCP2 head (p < .001) (explained by an increase in cortical vBMD (Δz = 1.07, p = .02) and reduction in the trabecular vBMD (Δz = −0.07, p = .09). Distal radius analysis did not show an overall effect of HOA; however, there was a gender-study group interaction (p = .044) explained by reduced trabecular vBMD in males (Δz = −1.23, p = .02). HOA was associated with lower failure load (−514 N; 95%CI, −1018 to −9; p = 0.05) apparent in males after adjustment for functional status. HOA is associated with reduced trabecular and increased cortical vBMD in the MCP2 head and a reduction in radial trabecular vBMD and bone strength in males. Further investigations of gender-specific changes of bone architecture in HOA are warranted. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.  相似文献   
23.
24.
25.
Peacekeeping missions involve experiences that may impact the mental health of participating soldiers. However, research on the long-term mental health consequences of peacekeeping is sparse. The present study aimed to find the prevalence of mental health problems (MHPs), possible MHP predictors, and associations between predictors and MHPs in Norwegian peacekeepers 18–38 years after deployment to a United Nations peacekeeping mission. We used data from a cross-sectional, postdeployment survey of Norwegian peacekeepers who served in Lebanon between 1978 and 1998 (N = 10,605). Participants were assessed for posttraumatic stress disorder (PTSD); anxiety; depression; insomnia; alcohol misuse; drug misuse; and exposure to pre-, peri-, and postdeployment stressors. Logistic regressions were executed to explore key variables associated with MHPs. Total MHP prevalence was 15.1%, 95% CI [14.4, 15.8]. The estimates for specific disorders were 0.1% for drug misuse, 3.4% for alcohol misuse, 4.0% for depression, 6.2% for PTSD, 6.4% for anxiety, and 9.3% for insomnia. Postdeployment stressors, OR = 1.91, 95% CI [1.79, 2.04]; employment status, OR = 1.41, 95% CI [1.33, 1.48]; and traumatic exposure during deployment, OR = 1.11, 95% CI [1.09, 1.12], were positively related to PTSD, χ2(17, N = 8,568) = 1,791.299, p < .001. Similar patterns were found for the other MHPs. Considering that most participants (84.9%) reported low symptom levels, our findings challenge the widespread public perception that most peacekeepers have MHPs. Moreover, our results indicate that future peacekeepers should be prepared for challenges they may face not only during deployment but also in the years following their homecoming.  相似文献   
26.
In developing countries, like Indonesia, apheresis is still a relative new procedure. Nowadays, therapeutic apheresis procedures are performed in the field of hematology and neurology, especially in the teaching hospitals in Indonesia. Therapeutic apheresis procedure, that is, leukocytapheresis, therapeutic plasma exchange (TPE), and thrombocytapheresis are already performed. In the period 2009–2013, 204 apheresis procedures in 137 patients to reduce the leukocytes, 72 TPE procedures in 17 patients, and 14 thrombocyte reductions were performed in the Sardjito hospital, Yogyakarta, Indonesia. In the future, to improve the therapeutic apheresis implementation, it is important to increase the insurance coverage and also should be considered to introduce the apheresis medicine into the curriculum of appropriate physician programs in Indonesia. Especially in Indonesia, a lot of efforts are still being needed to improve implementation of therapeutic apheresis. J. Clin. Apheresis 30:139–140, 2015. © 2014 Wiley Periodicals, Inc.  相似文献   
27.
28.
The repair of massive cuff defects by direct suture often is impossible. In these cases, a repair by musculo–tendineous flaps (latissimus-dorsi, pectoralis or deltoideus) is required. It was the goal of this study to evaluate the result of delta-flap repair in case of massive cuff defects with a diameter of 5 cm or more. Between 1998 and 2000 for all patients who were suffering from a massive rotator cuff tear more than 5 cm a deltoid transfer was performed. A total of 20 patients (14 male, 6 female; age: 60.9 ± 8.7 years) were available for a follow-up after 47.2 ± 8.0 (range, 36 to 60) month. The operation included an arthroscopic evaluation, acromioplasty with resection of the lateral clavicular end, and biceps tenodesis. The cuff defect was repaired by transfer a muscular flap from the anterior part of the deltoid (about 2×6 cm) into the defect. The patients subjectively rated their result—10 excellent, 9 good, and 1 poor. Preoperatively, the Constant amounted 26.3 ± 5.1 points. At follow-up, the score significantly increased to 74.5 ± 8.5 points. The acromiohumeral distance increased from 4.9 ± 1.1 to 9.2 ± 1.7 mm. In MRI examination of 11 patients all had an intact flap. Two complications (a wound hematoma and a deep infection) did not influence the result. The repair of massive rotator cuff tears by a deltoid transfer produces acceptable clinical and radiological results.  相似文献   
29.
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