全文获取类型
收费全文 | 75673篇 |
免费 | 5548篇 |
国内免费 | 204篇 |
专业分类
耳鼻咽喉 | 955篇 |
儿科学 | 2002篇 |
妇产科学 | 1734篇 |
基础医学 | 12197篇 |
口腔科学 | 1876篇 |
临床医学 | 7079篇 |
内科学 | 15124篇 |
皮肤病学 | 1175篇 |
神经病学 | 7255篇 |
特种医学 | 3151篇 |
外国民族医学 | 46篇 |
外科学 | 10285篇 |
综合类 | 651篇 |
一般理论 | 87篇 |
预防医学 | 5829篇 |
眼科学 | 1531篇 |
药学 | 5657篇 |
中国医学 | 205篇 |
肿瘤学 | 4586篇 |
出版年
2022年 | 437篇 |
2021年 | 1238篇 |
2020年 | 802篇 |
2019年 | 1139篇 |
2018年 | 1399篇 |
2017年 | 955篇 |
2016年 | 1115篇 |
2015年 | 1344篇 |
2014年 | 1669篇 |
2013年 | 2844篇 |
2012年 | 3754篇 |
2011年 | 3885篇 |
2010年 | 2706篇 |
2009年 | 2328篇 |
2008年 | 3540篇 |
2007年 | 3757篇 |
2006年 | 3748篇 |
2005年 | 3578篇 |
2004年 | 3599篇 |
2003年 | 3254篇 |
2002年 | 3296篇 |
2001年 | 2343篇 |
2000年 | 2350篇 |
1999年 | 2162篇 |
1998年 | 1031篇 |
1997年 | 856篇 |
1996年 | 754篇 |
1995年 | 761篇 |
1994年 | 639篇 |
1993年 | 694篇 |
1992年 | 1570篇 |
1991年 | 1501篇 |
1990年 | 1434篇 |
1989年 | 1430篇 |
1988年 | 1177篇 |
1987年 | 1178篇 |
1986年 | 1129篇 |
1985年 | 1050篇 |
1984年 | 780篇 |
1983年 | 728篇 |
1982年 | 525篇 |
1981年 | 506篇 |
1980年 | 428篇 |
1979年 | 672篇 |
1978年 | 411篇 |
1977年 | 397篇 |
1975年 | 408篇 |
1974年 | 438篇 |
1973年 | 390篇 |
1972年 | 376篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Ingmar Fleps Pierre Guy Stephen J Ferguson Peter A Cripton Benedikt Helgason 《Journal of bone and mineral research》2019,34(10):1837-1850
The majority of hip fractures in the elderly are the result of a fall from standing or from a lower height. Current injury models focus mostly on femur strength while neglecting subject-specific loading. This article presents an injury modeling strategy for hip fractures related to sideways falls that takes subject-specific impact loading into account. Finite element models (FEMs) of the human body were used to predict the experienced load and the femoral strength in a single model. We validated these models for their predicted peak force, effective pelvic stiffness, and fracture status against matching ex vivo sideways fall impacts (n = 11) with a trochanter velocity of 3.1 m/s. Furthermore, they were compared to sideways impacts of volunteers with lower impact velocities that were previously conducted by other groups. Good agreement was found between the ex vivo experiments and the FEMs with respect to peak force (root mean square error [RMSE] = 10.7%, R2 = 0.85) and effective pelvic stiffness (R2 = 0.92, RMSE = 12.9%). The FEMs were predictive of the fracture status for 10 out of 11 specimens. Compared to the volunteer experiments from low height, the FEMs overestimated the peak force by 25% for low BMI subjects and 8% for high BMI subjects. The effective pelvic stiffness values that were derived from the FEMs were comparable to those derived from impacts with volunteers. The force attenuation from the impact surface to the femur ranged between 27% and 54% and was highly dependent on soft tissue thickness (R2 = 0.86). The energy balance in the FEMS showed that at the time of peak force 79% to 93% of the total energy is either kinetic or was transformed to soft tissue deformation. The presented FEMs allow for direct discrimination between fracture and nonfracture outcome for sideways falls and bridge the gap between impact testing with volunteers and impact conditions representative of real life falls. © 2019 American Society for Bone and Mineral Research. 相似文献
4.
5.
6.
Factors predicting the development of pressure ulcers in an at‐risk population who receive standardized preventive care: secondary analyses of a multicentre randomised controlled trial
下载免费PDF全文
![点击此处可从《Journal of advanced nursing》网站下载免费的PDF全文](/ch/ext_images/free.gif)
7.
8.
Bielik Peter Bonczek Ondřej Krejčí Přemysl Zeman Tomáš Izakovičová-Hollá Lydie Šoukalová Jana Vaněk Jiří Vojtěšek Bořivoj Lochman Jan Balcar Vladimir J. Šerý Omar 《Clinical oral investigations》2022,26(12):7045-7055
Clinical Oral Investigations - The aim of this study was the analysis of WNT10A variants in seven families of probands with various forms of tooth agenesis and self-reported family history of... 相似文献
9.
W. Do T. Elzerman R. de Bree A. Rosenberg T. Forouzanfar E.M. Van Cann 《International journal of oral and maxillofacial surgery》2021,50(5):591-597
The aim of this study was to analyse the effect of body mass index (BMI), both low and high values, on the perioperative complication rate in patients with oral squamous cell carcinoma (OSCC). The medical records of 259 patients operated between 2014 and 2017 for OSCC were reviewed. Univariate and multivariate analyses were performed. Sixty of the 259 patients developed 87 complications. Low or high BMI was not associated with the perioperative complication rate. A longer operating time and increased blood loss were associated with a higher perioperative complication rate and higher Clavien–Dindo grade. Low BMI, American Society of Anesthesiologists score 2 and 3, a longer operating time, and increased blood loss were associated with a longer hospital stay. Low BMI was associated with a longer hospital stay. Neither low nor high BMI was associated with the perioperative complication rate. A longer operating time and increased blood loss were associated with a higher perioperative complication rate and higher Clavien–Dindo grade. 相似文献
10.
Quang Ngoc Nguyen Linh Dieu Vuong Van-Long Truong To Van Ta Nam Trung Nguyen Hung Phi Nguyen Ha Hoang Chu 《Pathology, research and practice》2019,215(5):885-892
Genetic and epigenetic alterations importantly contribute to the pathogenesis of lung cancer. In the study, we measured the frequency and distribution of molecular abnormalities of EGFR as well as the aberrant promoter methylations of BRCA1, MGMT, MLH1, and RASSF1A in Vietnamese lung adenocarcinomas. We investigated the association between genetic and epigenetic alteration, and between each abnormality with clinicopathologic parameters. Somatic EGFR mutation that was found in 49/139 (35.3%) lung adenocarcinomas showed a significant association with young age, female gender, and non-smokers. EGFR overexpression was identified in 82 tumors (59.0%) and statistical relationships with EGFR or BRCA1 methylation but not EGFR mutation. In addition, EGFR, BRCA1, MGMT, MLH1, and RASSF1A methylations were found in 33 (23.7%), 41 (29.5%), 46 (33.1%), 28 (20.1%), and 41 (29.5%) cases of a total of 139 lung adenocarcinomas, respectively. The RASSF1A methylation was found to be linked to the smoking habit. Methylations in MGMT and RASSF1A were also found to correlate with metastasis status. Furthermore, the distribution of EGFR mutation and that of BRCA1, MGMT or RASSF1A methylation were significantly exclusive in lung adenocarcinomas. The main finding of our study demonstrate that epigenetic abnormalities might play a critical role for the lung tumorigenesis in patients with smoking history and metastasis, and partly affect the predictive value of EGFR mutations through blocking expression due to promoter EGFR hypermethylation. Mutually exclusive distribution of genetic and epigenetic alterations reflects differently biological characteristics in the etiology of lung adenocarcinomas. 相似文献