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   1142篇
  免费   107篇
  2021年   8篇
  2020年   9篇
  2019年   14篇
  2018年   16篇
  2017年   12篇
  2016年   16篇
  2015年   31篇
  2014年   33篇
  2013年   46篇
  2012年   70篇
  2011年   52篇
  2010年   39篇
  2009年   40篇
  2008年   55篇
  2007年   70篇
  2006年   54篇
  2005年   49篇
  2004年   51篇
  2003年   45篇
  2002年   48篇
  2001年   42篇
  2000年   36篇
  1999年   22篇
  1998年   13篇
  1997年   14篇
  1996年   14篇
  1995年   10篇
  1994年   10篇
  1993年   15篇
  1992年   23篇
  1991年   25篇
  1990年   16篇
  1989年   15篇
  1988年   13篇
  1987年   8篇
  1985年   10篇
  1984年   15篇
  1982年   7篇
  1979年   9篇
  1978年   8篇
  1977年   8篇
  1976年   11篇
  1975年   12篇
  1974年   10篇
  1973年   14篇
  1972年   16篇
  1971年   10篇
  1970年   9篇
  1968年   13篇
  1967年   7篇
排序方式: 共有1249条查询结果,搜索用时 812 毫秒
41.
42.
This study aimed to examine whether lung tissue extracellular matrix (ECM) hydrogels have protective effects on radiation-induced lung injury (RILI). The cytocompatibility and histocompatibility were tested for the obtained ECM-derived hydrogel. Sprague–Dawley rats were randomly divided into three groups (n = 18): control group (control); rats receiving irradiation and intratracheal injection of normal saline (IR + NS); and rats receiving irradiation and intratracheal injection of lung ECM-derived hydrogel (IR + ECM). The wet/dry weight ratio was used to evaluate the congestion and edema of the lungs. Histopathological analysis of lung tissues was performed using hemotoxylin and eosin staining and Masson's trichrome staining. Immunohistochemical staining and western blot analyses were carried out to determine the expression of epithelial–mesenchymal transition (EMT)-related proteins in lung tissues (E-cadherin, α-smooth muscle actin [α-SMA], and vimentin). In addition, tumor necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1) and interleukin-6 (IL-6), hydroxyproline, malondialdehyde (MDA), and superoxide dismutase (SOD) levels were also evaluated. The ECM-derived hydrogels had good cytocompatibility and histocompatibility. ECM-derived hydrogel treatment improved lung histopathology injury and pulmonary edema. Higher expression of E-cadherin and lower expression of vimentin and α-SMA were found in the IR + ECM group compared with those in the IR + NS group. Hydroxyproline levels were reduced by ECM-derived hydrogel treatment compared with those in the IR + NS group. Obvious increases of TNF-α, IL-6, and TGF-β1 were identified following irradiation. Marked reductions in MDA content and increases in SOD were induced by ECM-derived hydrogel treatment in rats after radiation. ECM-derived hydrogels were shown to protect against RILI, potentially by reducing EMT, inflammation, and oxidative damage.  相似文献   
43.
44.
45.
46.
The Netherlands Organisation of Health Research and Development started in 2008 the Dutch National Care for the Elderly Programme (in Dutch abbreviated as NPO) with the aim to improve the quality of life for the frail older people through better quality of care (health, social, community) which is tailored to the needs and wants of older people. The delivery of good care is related with competent professional behaviour which is inextricably linked to the education of professionals. This article presents an overview of 32 educational programmes developed within the NPO. Within the NPO different educational programmes were developed on relevant themes to improve elderly care. However, the programmes focused mainly on professionals in health care, especially those working in primary care. For nurses and nursing assistants and more or less for physicians also different educational programmes were developed. Educational programmes for paramedics or professionals working in social care, housing or in the municipalities were scarce. This is also the case for specific themes in elderly care like loneliness or (domestic) violence. Moreover, none of the experiments focused on older people or informal care givers. Although 22 of the 32 projects developed educational programmes for different groups, multi – or interdisciplinary education is rare in these programmes. Based on the overview we advise the development of more educational programmes on: target groups which were less or not addressed in the NPO, like professionals in social care and paramedics; multi- or interdisciplinary collaboration; and themes, like loneliness in older people and elder abuse.  相似文献   
47.
48.
49.
A multi-population biofilm model for completely autotrophic nitrogen removal was developed and implemented in the simulation program AQUASIM to corroborate the concept of a redox-stratification controlled biofilm (ReSCoBi). The model considers both counter- and co-diffusion biofilm geometries. In the counter-diffusion biofilm, oxygen is supplied through a gas-permeable membrane that supports the biofilm while ammonia (NH(4)(+)) is supplied from the bulk liquid. On the contrary, in the co-diffusion biofilm, both oxygen and NH(4)(+) are supplied from the bulk liquid. Results of the model revealed a clear stratification of microbial activities in both of the biofilms, the resulting chemical profiles, and the obvious effect of the relative surface loadings of oxygen and NH(4)(+) (J(O(2))/J(NH(4)(+))) on the reactor performances. Steady-state biofilm thickness had a significant but different effect on T-N removal for co- and counter-diffusion biofilms: the removal efficiency in the counter-diffusion biofilm geometry was superior to that in the co-diffusion counterpart, within the range of 450-1,400 microm; however, the efficiency deteriorated with a further increase in biofilm thickness, probably because of diffusion limitation of NH(4)(+). Under conditions of oxygen excess (J(O(2))/J(NH(4)(+)) > 3.98), almost all NH(4)(+) was consumed by aerobic ammonia oxidation in the co-diffusion biofilm, leading to poor performance, while in the counter-diffusion biofilm, T-N removal efficiency was maintained because of the physical location of anaerobic ammonium oxidizers near the bulk liquid. These results clearly reveal that counter-diffusion biofilms have a wider application range for autotrophic T-N removal than co-diffusion biofilms.  相似文献   
50.
Epidemic modeling in complex realities   总被引:1,自引:0,他引:1  
  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