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   31915篇
  免费   2958篇
  国内免费   186篇
耳鼻咽喉   330篇
儿科学   1103篇
妇产科学   724篇
基础医学   3627篇
口腔科学   646篇
临床医学   3317篇
内科学   6773篇
皮肤病学   552篇
神经病学   2686篇
特种医学   1062篇
外科学   4855篇
综合类   805篇
一般理论   14篇
预防医学   2106篇
眼科学   1309篇
药学   2330篇
  1篇
中国医学   131篇
肿瘤学   2688篇
  2023年   242篇
  2022年   292篇
  2021年   767篇
  2020年   521篇
  2019年   733篇
  2018年   863篇
  2017年   666篇
  2016年   743篇
  2015年   851篇
  2014年   1125篇
  2013年   1335篇
  2012年   2024篇
  2011年   2076篇
  2010年   1253篇
  2009年   1135篇
  2008年   1822篇
  2007年   1762篇
  2006年   1638篇
  2005年   1561篇
  2004年   1564篇
  2003年   1385篇
  2002年   1229篇
  2001年   1146篇
  2000年   1033篇
  1999年   883篇
  1998年   341篇
  1997年   260篇
  1996年   237篇
  1995年   229篇
  1994年   200篇
  1993年   174篇
  1992年   520篇
  1991年   487篇
  1990年   442篇
  1989年   405篇
  1988年   368篇
  1987年   340篇
  1986年   333篇
  1985年   328篇
  1984年   223篇
  1983年   207篇
  1982年   142篇
  1981年   108篇
  1980年   112篇
  1979年   161篇
  1978年   93篇
  1977年   105篇
  1976年   72篇
  1974年   85篇
  1973年   71篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Prevalence of osteoporosis is more than 50% in older adults, yet current clinical methods for diagnosis that rely on areal bone mineral density (aBMD) fail to detect most individuals who have a fragility fracture. Bone fragility can manifest in different forms, and a “one-size-fits-all” approach to diagnosis and management of osteoporosis may not be suitable. High-resolution peripheral quantitative computed tomography (HR-pQCT) provides additive information by capturing information about volumetric density and microarchitecture, but interpretation is challenging because of the complex interactions between the numerous properties measured. In this study, we propose that there are common combinations of bone properties, referred to as phenotypes, that are predisposed to different levels of fracture risk. Using HR-pQCT data from a multinational cohort (n = 5873, 71% female) between 40 and 96 years of age, we employed fuzzy c-means clustering, an unsupervised machine-learning method, to identify phenotypes of bone microarchitecture. Three clusters were identified, and using partial correlation analysis of HR-pQCT parameters, we characterized the clusters as low density, low volume, and healthy bone phenotypes. Most males were associated with the healthy bone phenotype, whereas females were more often associated with the low volume or low density bone phenotypes. Each phenotype had a significantly different cumulative hazard of major osteoporotic fracture (MOF) and of any incident osteoporotic fracture (p < 0.05). After adjustment for covariates (cohort, sex, and age), the low density followed by the low volume phenotype had the highest association with MOF (hazard ratio = 2.96 and 2.35, respectively), and significant associations were maintained when additionally adjusted for femoral neck aBMD (hazard ratio = 1.69 and 1.90, respectively). Further, within each phenotype, different imaging biomarkers of fracture were identified. These findings suggest that osteoporotic fracture risk is associated with bone phenotypes that capture key features of bone deterioration that are not distinguishable by aBMD. © 2021 American Society for Bone and Mineral Research (ASBMR).  相似文献   
4.
Abstract

Objective

Ras wild-type metastatic colorectal cancers (mCRC) may be treated with anti-vascular endothelial growth factor (VEGF) or anti-epidermal growth factor receptor (EGFR) agents. We aim to estimate patients’ preferences for mCRC treatment and relative importance of cost, efficacy improvement, avoidance of side effects and therapy convenience, and relative uptake between profiles that resemble Bevacizumab (anti-VEGF) and Cetuximab (anti-EGFR), two commonly prescribed mCRC targeted therapies.  相似文献   
5.
6.
7.
The profile and reach of physiotherapy has expanded in areas of extended scope of practice, and broader engagement with population needs beyond the individual treatment encounter. These changes raise increasingly complex ethical challenges evidenced by growth in physiotherapy-based ethics studies and discussions. This paper examines how a broad cross section of Australian physiotherapists perceive, interpret, and respond to ethical challenges in their work contexts and how professional codes of conduct are used in their practice. Using an interpretive qualitative methodology, purposive sampling of 88 members of national clinical special interest groups were recruited for focus group discussions. Narrative-based and thematic data analysis identified ethical challenges as emerging from specific clinical contexts, and influenced by health organizations, funding policies, workplace relationships, and individually held perspectives. Five themes were developed to represent these findings: (1) the working environment, (2) balancing diverse needs and expectation, (3) defining ethics, (4) striving to act ethically, and (5) talking about ethics. The results portray a diverse and complex ethical landscape where therapists encounter and grapple with ethical questions emerging from the impact of funding models and policies affecting clinical work, expanding boundaries and scope of practice and changing professional roles and relationships. Codes of conduct were described as foundational ethical knowledge but not always helpful for “in the moment” ethical decision-making. Based on this research, we suggest how codes of conduct, educators, and professional associations could cultivate and nurture ethics capability in physiotherapy practitioners for these contemporary challenges.  相似文献   
8.
9.
A pathological feature in atherosclerosis is the dysfunction and death of vascular endothelial cells (EC). Oxidized low‐density lipoprotein (LDL), known to accumulate in the atherosclerotic arterial walls, impairs endothelium‐dependent relaxation and causes EC apoptosis. A major bioactive ingredient of the oxidized LDL is lysophosphatidylcholine (LPC), which at higher concentrations causes apoptosis and necrosis in various EC. There is hitherto no report on LPC‐induced cytotoxicity in brain EC. In this work, we found that LPC caused cytosolic Ca2+ overload, mitochondrial membrane potential decrease, p38 activation, caspase 3 activation and eventually apoptotic death in mouse cerebral bEND.3 EC. In contrast to reported reactive oxygen species (ROS) generation by LPC in other EC, LPC did not trigger ROS formation in bEND.3 cells. Pharmacological inhibition of p38 alleviated LPC‐inflicted cell death. We examined whether heparin could be cytoprotective: although it could not suppress LPC‐triggered Ca2+ signal, p38 activation and mitochondrial membrane potential drop, it did suppress LPC‐induced caspase 3 activation and alleviate LPC‐inflicted cytotoxicity. Our data suggest LPC apoptotic death mechanisms in bEND.3 might involve mitochondrial membrane potential decrease and p38 activation. Heparin is protective against LPC cytotoxicity and might intervene steps between mitochondrial membrane potential drop/p38 activation and caspase 3 activation.  相似文献   
10.
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