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   159篇
  免费   10篇
  169篇
  2023年   2篇
  2022年   2篇
  2021年   6篇
  2020年   5篇
  2019年   3篇
  2018年   7篇
  2017年   1篇
  2016年   3篇
  2015年   5篇
  2014年   10篇
  2013年   7篇
  2012年   12篇
  2011年   9篇
  2010年   6篇
  2009年   5篇
  2008年   10篇
  2007年   9篇
  2006年   7篇
  2005年   11篇
  2004年   17篇
  2003年   3篇
  2002年   5篇
  2001年   4篇
  2000年   3篇
  1999年   4篇
  1998年   2篇
  1997年   3篇
  1996年   1篇
  1995年   2篇
  1993年   2篇
  1992年   1篇
  1989年   1篇
  1968年   1篇
排序方式: 共有169条查询结果,搜索用时 15 毫秒
31.
32.
33.
34.
35.
Neurochemical Research - Cerebral ischemia is known to trigger a series of intracellular events such as changes in metabolism, membrane function and intracellular transduction, which eventually...  相似文献   
36.

Background

Liposomal-based gadolinium (Gd) nanoparticles have elicited significant interest for use as blood pool and molecular magnetic resonance imaging (MRI) contrast agents. Previous generations of liposomal MR agents contained gadolinium-chelates either within the interior of liposomes (core-encapsulated gadolinium liposomes) or presented on the surface of liposomes (surface-conjugated gadolinium liposomes). We hypothesized that a liposomal agent that contained both core-encapsulated gadolinium and surface-conjugated gadolinium, defined herein as dual-mode gadolinium (Dual-Gd) liposomes, would result in a significant improvement in nanoparticle-based T1 relaxivity over the previous generations of liposomal agents. In this study, we have developed and tested, both in vitro and in vivo, such a dual-mode liposomal-based gadolinium contrast agent.

Methodology/Principal Findings

Three types of liposomal agents were fabricated: core-encapsulated, surface-conjugated and dual-mode gadolinium liposomes. In vitro physico-chemical characterizations of the agents were performed to determine particle size and elemental composition. Gadolinium-based and nanoparticle-based T1 relaxivities of various agents were determined in bovine plasma. Subsequently, the agents were tested in vivo for contrast-enhanced magnetic resonance angiography (CE-MRA) studies. Characterization of the agents demonstrated the highest gadolinium atoms per nanoparticle for Dual-Gd liposomes. In vitro, surface-conjugated gadolinium liposomes demonstrated the highest T1 relaxivity on a gadolinium-basis. However, Dual-Gd liposomes demonstrated the highest T1 relaxivity on a nanoparticle-basis. In vivo, Dual-Gd liposomes resulted in the highest signal-to-noise ratio (SNR) and contrast-to-noise ratio in CE-MRA studies.

Conclusions/Significance

The dual-mode gadolinium liposomal contrast agent demonstrated higher particle-based T1 relaxivity, both in vitro and in vivo, compared to either the core-encapsulated or the surface-conjugated liposomal agent. The dual-mode gadolinium liposomes could enable reduced particle dose for use in CE-MRA and increased contrast sensitivity for use in molecular imaging.  相似文献   
37.
Birth–death–movement processes, modulated by interactions between individuals, are fundamental to many cell biology processes. A key feature of the movement of cells within in vivo environments is the interactions between motile cells and stationary obstacles. Here we propose a multi-species model of individual-level motility, proliferation and death. This model is a spatial birth–death–movement stochastic process, a class of individual-based model (IBM) that is amenable to mathematical analysis. We present the IBM in a general multi-species framework and then focus on the case of a population of motile, proliferative agents in an environment populated by stationary, non-proliferative obstacles. To analyse the IBM, we derive a system of spatial moment equations governing the evolution of the density of agents and the density of pairs of agents. This approach avoids making the usual mean-field assumption so that our models can be used to study the formation of spatial structure, such as clustering and aggregation, and to understand how spatial structure influences population-level outcomes. Overall the spatial moment model provides a reasonably accurate prediction of the system dynamics, including important effects such as how varying the properties of the obstacles leads to different spatial patterns in the population of agents.  相似文献   
38.
39.
Phenylketonuria (PKU) is a metabolic disorder caused by phenylalanine hydroxylase deficiency leading to increased levels of phenylalanine in the brain. Hyperactivity is reportedly induced by a high level of orexin A, and therefore orexin A content was studied in the PKU mice. Hypothalamus and brain stem had higher levels of orexin A compared to cerebrum and cerebellum both in wild type and PKU mice brains as observed by radioimmunoassay method. Interestingly, all these regions of the brain in PKU mouse showed a higher level of orexin A compared to the wild type. Heart and plasma also had higher levels of orexin A in PKU compared to the wild type. Immunohistochemical analysis revealed an increased number of orexin A–stained cells in the brain and heart of PKU mouse compared to the wild type. This is the first report of increased level of orexin in the PKU mouse brain. Hyperactivity is commonly observed in children with PKU; thus these findings suggest that orexin A is a contributing factor for the hyperactivity.  相似文献   
40.
This study was aimed for the detection of Vibrio parahaemolyticus by biochemical and molecular methods in seafood samples collected from the markets of Cochin located at the southwest coast of India. A total of seventy-two V. parahaemolyticus cultures were isolated by selecting sucrose and cellobiose non-fermenting colonies. All the biochemically confirmed strains were found to have 368-bp toxR gene fragment, while an additional 24% of the samples were confirmed as V. parahaemolyticus by toxR based polymerase chain reaction (PCR) from enrichment broths. PCR based methods are used to detect tdh, trh, and orf8 genes for the identification of pathogenic and pandemic V. parahaemolyticus. Only one out of two urease positive isolates amplified the trh (500bp) gene. About 10% of the isolates showed weak haemolysis and none were found to amplify tdh (269 bp) and orf8 (746 bp) genes, thus indicating the meager incidence of pandemic strains from this area. The incidence of trh positive isolates from market samples signals towards the adoption of stringent seafood safety measures for the products meant for human consumption.  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