全文获取类型
收费全文 | 6705篇 |
免费 | 539篇 |
国内免费 | 17篇 |
专业分类
耳鼻咽喉 | 56篇 |
儿科学 | 224篇 |
妇产科学 | 172篇 |
基础医学 | 954篇 |
口腔科学 | 96篇 |
临床医学 | 889篇 |
内科学 | 1243篇 |
皮肤病学 | 90篇 |
神经病学 | 644篇 |
特种医学 | 178篇 |
外科学 | 861篇 |
综合类 | 79篇 |
一般理论 | 1篇 |
预防医学 | 749篇 |
眼科学 | 179篇 |
药学 | 368篇 |
中国医学 | 13篇 |
肿瘤学 | 465篇 |
出版年
2023年 | 40篇 |
2022年 | 33篇 |
2021年 | 142篇 |
2020年 | 121篇 |
2019年 | 187篇 |
2018年 | 225篇 |
2017年 | 141篇 |
2016年 | 161篇 |
2015年 | 187篇 |
2014年 | 237篇 |
2013年 | 300篇 |
2012年 | 463篇 |
2011年 | 460篇 |
2010年 | 244篇 |
2009年 | 239篇 |
2008年 | 384篇 |
2007年 | 404篇 |
2006年 | 326篇 |
2005年 | 352篇 |
2004年 | 337篇 |
2003年 | 302篇 |
2002年 | 292篇 |
2001年 | 138篇 |
2000年 | 115篇 |
1999年 | 98篇 |
1998年 | 56篇 |
1997年 | 46篇 |
1996年 | 59篇 |
1995年 | 42篇 |
1994年 | 33篇 |
1993年 | 40篇 |
1992年 | 73篇 |
1991年 | 77篇 |
1990年 | 82篇 |
1989年 | 82篇 |
1988年 | 57篇 |
1987年 | 63篇 |
1986年 | 57篇 |
1985年 | 54篇 |
1984年 | 40篇 |
1983年 | 41篇 |
1982年 | 35篇 |
1981年 | 24篇 |
1980年 | 35篇 |
1979年 | 48篇 |
1978年 | 37篇 |
1977年 | 23篇 |
1976年 | 31篇 |
1974年 | 29篇 |
1973年 | 24篇 |
排序方式: 共有7261条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Tina D. Kristensen Ren C. W. Mandl Jayachandra M. Raghava Kasper Jessen Jens Richardt M. Jepsen Birgitte Fagerlund Louise B. Glenthj Christina Wenneberg Kristine Krakauer Christos Pantelis Merete Nordentoft Birte Y. Glenthj Bjrn H. Ebdrup 《Human brain mapping》2019,40(18):5185-5201
In schizophrenia patients, cognitive functions appear linked to widespread alterations in cerebral white matter microstructure. Here we examine patterns of associations between regional white matter and cognitive functions in individuals at ultra‐high risk for psychosis. One hundred and sixteen individuals at ultra‐high risk for psychosis and 49 matched healthy controls underwent 3 T magnetic resonance diffusion‐weighted imaging and cognitive assessments. Group differences on fractional anisotropy were tested using tract‐based spatial statistics. Group differences in cognitive functions, voxel‐wise as well as regional fractional anisotropy were tested using univariate general linear modeling. Multivariate partial least squares correlation analyses tested for associations between patterns of regional fractional anisotropy and cognitive functions. Univariate analyses revealed significant impairments on cognitive functions and lower fractional anisotropy in superior longitudinal fasciculus and cingulate gyrus in individuals at ultra‐high risk for psychosis. Partial least squares correlation analysis revealed different associations between patterns of regional fractional anisotropy and cognitive functions in individuals at ultra‐high risk for psychosis compared to healthy controls. Widespread higher fractional anisotropy was associated with better cognitive functioning for individuals at ultra‐high risk for psychosis, but not for the healthy controls. Furthermore, patterns of cognitive functions were associated with an interaction‐effect on regional fractional anisotropy in fornix, medial lemniscus, uncinate fasciculus, and superior cerebellar peduncle. Aberrant associations between patterns of cognitive functions to white matter may be explained by dysmyelination. 相似文献
5.
International Journal of Clinical Pharmacy - Background Medication management is undertaken by caregivers of people who have intellectual or developmental disabilities. Objective The objectives... 相似文献
6.
7.
8.
Dougherty Ryan J. Hoang Tina D. Launer Lenore J. Jacobs David R. Sidney Stephen Yaffe Kristine 《Brain imaging and behavior》2022,16(2):637-644
Brain Imaging and Behavior - The purpose of this study was to investigate whether long-term television viewing patterns, a common sedentary behavior, in early to mid-adulthood is associated with... 相似文献
9.
10.
Melatonin improves bone mineral density at the femoral neck in postmenopausal women with osteopenia: a randomized controlled trial 下载免费PDF全文
Anne Kristine Amstrup Tanja Sikjaer Lene Heickendorff Leif Mosekilde Lars Rejnmark 《Journal of pineal research》2015,59(2):221-229
Melatonin is known for its regulation of circadian rhythm. Recently, studies have shown that melatonin may have a positive effect on the skeleton. By increasing age, the melatonin levels decrease, which may lead to a further imbalanced bone remodeling. We aimed to investigate whether treatment with melatonin could improve bone mass and integrity in humans. In a double‐blind RCT, we randomized 81 postmenopausal osteopenic women to 1‐yr nightly treatment with melatonin 1 mg (N = 20), 3 mg (N = 20), or placebo (N = 41). At baseline and after 1‐yr treatment, we measured bone mineral density (BMD) by dual X‐ray absorptiometry, quantitative computed tomography (QCT), and high‐resolution peripheral QCT (HR‐pQCT) and determined calciotropic hormones and bone markers. Mean age of the study subjects was 63 (range 56–73) yr. Compared to placebo, femoral neck BMD increased by 1.4% in response to melatonin (P < 0.05) in a dose‐dependent manner (P < 0.01), as BMD increased by 0.5% in the 1 mg/day group (P = 0.55) and by 2.3% (P < 0.01) in the 3 mg/day group. In the melatonin group, trabecular thickness in tibia increased by 2.2% (P = 0.04), and volumetric bone mineral density (vBMD) in the spine, by 3.6% (P = 0.04) in the 3 mg/day. Treatment did not significantly affect BMD at other sites or levels of bone turnover markers; however, 24‐hr urinary calcium was decreased in response to melatonin by 12.2% (P = 0.02). In conclusion, 1‐yr treatment with melatonin increased BMD at femoral neck in a dose‐dependent manner, while high‐dose melatonin increased vBMD in the spine. Further studies are needed to assess the mechanisms of action and whether the positive effect of nighttime melatonin will protect against fractures. 相似文献