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   416903篇
  免费   19856篇
  国内免费   835篇
耳鼻咽喉   5356篇
儿科学   12173篇
妇产科学   9531篇
基础医学   60331篇
口腔科学   11470篇
临床医学   30465篇
内科学   91878篇
皮肤病学   10779篇
神经病学   36858篇
特种医学   12488篇
外国民族医学   107篇
外科学   50611篇
综合类   1880篇
一般理论   110篇
预防医学   41127篇
眼科学   9122篇
药学   30619篇
中国医学   1357篇
肿瘤学   21332篇
  2023年   2142篇
  2022年   2032篇
  2021年   6619篇
  2020年   3836篇
  2019年   6966篇
  2018年   13456篇
  2017年   8662篇
  2016年   8275篇
  2015年   9318篇
  2014年   10413篇
  2013年   16152篇
  2012年   27090篇
  2011年   27640篇
  2010年   14018篇
  2009年   10808篇
  2008年   23449篇
  2007年   24884篇
  2006年   23633篇
  2005年   23119篇
  2004年   21647篇
  2003年   20068篇
  2002年   19034篇
  2001年   11563篇
  2000年   12522篇
  1999年   9962篇
  1998年   2009篇
  1997年   1507篇
  1992年   5393篇
  1991年   4789篇
  1990年   4680篇
  1989年   4171篇
  1988年   3917篇
  1987年   3654篇
  1986年   3576篇
  1985年   3304篇
  1984年   2461篇
  1983年   2091篇
  1979年   2392篇
  1978年   1649篇
  1977年   1581篇
  1975年   1679篇
  1974年   2082篇
  1973年   2135篇
  1972年   1983篇
  1971年   1938篇
  1970年   1815篇
  1969年   1924篇
  1968年   1851篇
  1967年   1638篇
  1966年   1457篇
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
91.
In May 2017, the Health and Environmental Sciences Institute's Genetic Toxicology Technical Committee hosted a workshop to discuss whether mode of action (MOA) investigation is enhanced through the application of the adverse outcome pathway (AOP) framework. As AOPs are a relatively new approach in genetic toxicology, this report describes how AOPs could be harnessed to advance MOA analysis of genotoxicity pathways using five example case studies. Each of these genetic toxicology AOPs proposed for further development includes the relevant molecular initiating events, key events, and adverse outcomes (AOs), identification and/or further development of the appropriate assays to link an agent to these events, and discussion regarding the biological plausibility of the proposed AOP. A key difference between these proposed genetic toxicology AOPs versus traditional AOPs is that the AO is a genetic toxicology endpoint of potential significance in risk characterization, in contrast to an adverse state of an organism or a population. The first two detailed case studies describe provisional AOPs for aurora kinase inhibition and tubulin binding, leading to the common AO of aneuploidy. The remaining three case studies highlight provisional AOPs that lead to chromosome breakage or mutation via indirect DNA interaction (inhibition of topoisomerase II, production of cellular reactive oxygen species, and inhibition of DNA synthesis). These case studies serve as starting points for genotoxicity AOPs that could ultimately be published and utilized by the broader toxicology community and illustrate the practical considerations and evidence required to formalize such AOPs so that they may be applied to genetic toxicity evaluation schemes. Environ. Mol. Mutagen. 61:114–134, 2020. © 2019 Wiley Periodicals, Inc.  相似文献   
92.
93.
Gray platelet syndrome (GPS) is a rare (<1/1 000 000) and inherited platelet function disorder characterized by macrothrombocytopenia, α-granule deficiency, and hemorrhages. Bleeding intensity does not correlate with platelet count nor with functional test results. We hereby describe the perioperative bleeding prevention and management of a patient with GPS requiring multiple redo cardiac surgeries.  相似文献   
94.
95.
We evaluated RNA stability of Ebola virus in EDTA blood and urine samples collected from infected patients and stored in West Africa’s environmental conditions. In blood, RNA was stable for at least 18 days when initial cycle threshold values were <30, but in urine, RNA degradation occurred more quickly.  相似文献   
96.
97.
Between the 1930s and 1960s Puerto Rico was transformed from a marginal United States territory into an industrialised ‘showcase of development’. This article investigates the organisation of milk station programmes on the island during this crucial period and how these reflected the circulation of child welfare knowledge, nutrition expertise and public health practices. During the Depression, these perspectives fostered a recast of the eugenic regeneration ideologies motivating medical assessments of and sanitary interventions with Puerto Rico’s rural poor since the nineteenth century. Innovations in nutrition knowledge and an emerging rural hygiene movement highlighted the negative health effects of the island’s monocrops economy. In this context, the nourishment of children’s bodies assumed symbolic and instrumental significance for the reconfiguration of colonial and developmental models promoted by the new Popular Democratic Party (PPD). The experience of public health professionals in relief work during the 1930s contributed to the articulation of food and nutrition as key elements of this party’s populist discourse. Programmes like milk stations became part of strategies to rear and manage the labour force needed in the industrial development model promoted by the PPD. From the perspective of poor Puerto Ricans, however, they were part of the materialisation of its promise of social justice for the poorer classes.  相似文献   
98.

Objectives

Short successive periods of skeletal muscle disuse have been suggested to substantially contribute to the observed loss of skeletal muscle mass over the life span. Hospitalization of older individuals due to acute illness, injury, or major surgery generally results in a mean hospital stay of 5 to 7 days, during which the level of physical activity is strongly reduced. We hypothesized that hospitalization following elective total hip arthroplasty is accompanied by substantial leg muscle atrophy in older men and women.

Design and participants

Twenty-six older patients (75 ± 1 years) undergoing elective total hip arthroplasty participated in this observational study.

Measurements

On hospital admission and on the day of discharge, computed tomographic (CT) scans were performed to assess muscle cross-sectional area (CSA) of both legs. During surgery and on the day of hospital discharge, a skeletal muscle biopsy was taken from the m. vastus lateralis of the operated leg to assess muscle fiber type–specific CSA.

Results

An average of 5.6 ± 0.3 days of hospitalization resulted in a significant decline in quadriceps (?3.4% ± 1.0%) and thigh muscle CSA (?4.2% ± 1.1%) in the nonoperated leg (P < .05). Edema resulted in a 10.3% ± 1.7% increase in leg CSA in the operated leg (P < .05). At hospital admission, muscle fiber CSA was smaller in the type II vs type I fibers (3326 ± 253 μm2 vs 4075 ± 279 μm2, respectively; P < .05). During hospitalization, type I and II muscle fiber CSA tended to increase, likely due to edema in the operated leg (P = .10).

Conclusions

Six days of hospitalization following elective total hip arthroplasty leads to substantial leg muscle atrophy in older patients. Effective intervention strategies are warranted to prevent the loss of muscle mass induced by short periods of muscle disuse during hospitalization.  相似文献   
99.
100.
The main clinical features of tyrosinemia type 1 usually appear in the first months of life, including fever, diarrhea, vomiting, liver involvement, growth failure, and renal proximal tubulopathy with subsequent hypophosphatemic rickets. An early diagnosis is crucial in order to provide specific management and to prevent complications. Here, we report on two cases referred primarily to pediatric nephrologists for the diagnosis of “neonatal tubulopathy” and management of “X-linked hypophosphatemia (XLH),” respectively. Our aim is to emphasize that (1) even a mixed tubulopathy can reveal tyrosinemia, and (2) tyrosinemia is a classic differential diagnosis of XLH that should not be forgotten, especially in the era of the anti-FGF23 burosumab.  相似文献   
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