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   198篇
  免费   14篇
  2023年   2篇
  2021年   4篇
  2020年   6篇
  2019年   9篇
  2017年   8篇
  2016年   5篇
  2015年   9篇
  2014年   17篇
  2013年   5篇
  2012年   20篇
  2011年   13篇
  2010年   5篇
  2009年   9篇
  2008年   10篇
  2007年   12篇
  2006年   11篇
  2005年   16篇
  2004年   9篇
  2003年   13篇
  2002年   7篇
  2001年   3篇
  2000年   6篇
  1999年   3篇
  1998年   4篇
  1996年   2篇
  1995年   1篇
  1993年   1篇
  1991年   2篇
排序方式: 共有212条查询结果,搜索用时 15 毫秒
1.
We propose a methodology for digitally fusing diagnostic decisions made by multiple medical experts in order to improve accuracy of diagnosis. Toward this goal, we report an experimental study involving nine experts, where each one was given more than 8,000 digital microscopic images of individual human red blood cells and asked to identify malaria infected cells. The results of this experiment reveal that even highly trained medical experts are not always self-consistent in their diagnostic decisions and that there exists a fair level of disagreement among experts, even for binary decisions (i.e., infected vs. uninfected). To tackle this general medical diagnosis problem, we propose a probabilistic algorithm to fuse the decisions made by trained medical experts to robustly achieve higher levels of accuracy when compared to individual experts making such decisions. By modelling the decisions of experts as a three component mixture model and solving for the underlying parameters using the Expectation Maximisation algorithm, we demonstrate the efficacy of our approach which significantly improves the overall diagnostic accuracy of malaria infected cells. Additionally, we present a mathematical framework for performing ‘slide-level’ diagnosis by using individual ‘cell-level’ diagnosis data, shedding more light on the statistical rules that should govern the routine practice in examination of e.g., thin blood smear samples. This framework could be generalized for various other tele-pathology needs, and can be used by trained experts within an efficient tele-medicine platform.  相似文献   
2.
BODIPY is an important fluorophores due to its enhanced photophysical and chemical properties including outstanding thermal/photochemical stability, intense absorption/emission profiles, high photoluminescence quantum yield, and small Stokes' shifts. In addition to BODIPY, indole and its derivatives have recently gained attention because of their structural properties and particularly biological importance, therefore these molecules have been widely used in sensing and biosensing applications. Here, we focus on recent studies that reported the incorporation of indole‐based BODIPY molecules as reporter molecules in sensing systems. We highlight the rationale for developing such systems and evaluate detection limits of the developed sensing platforms. Furthermore, we also review the application of indole‐based BODIPY molecules in bioimaging studies. This article includes the evaluation of indole‐based BODIPYs from synthesis to characterization and a comparison of the advantages and disadvantages of developed reporter systems, making it instructive for researchers in various disciplines for the design and development of similar systems.  相似文献   
3.
4.
Abstract

Porcine pancreatic lipase (PPL), Candida rugosa lipase (CRL), and Castor bean lipase (CBL) were immobilized on celite by deposition from aqueous solution by the addition of hexane. Lipolytic performance of free and immobilized lipases were compared and optimizations of lipolytic enzymatic reactions conditions were performed by free and immobilized derivatives using olive oil as substrate. Afterwards, the influence on lipolysis of castor oil of free lipases and immobilized lipase derivatives have been studied in the case of production of ricinoleic acid. All of the lipases performances were compared and enzyme derivative was selected to be very effective on the production of ricinoleic acid by lipolysis reaction. Various reaction parameters affecting the production of ricinoleic acid were investigated with selected the enzyme derivative.

The maximum ricinoleic acid yield was observed at pH 7–8, 50°C, for 3 hours of reaction period with immobilized 1,3-specific PPL on celite. The kinetic constants Km and Vmax were calculated as 1.6 × 10?4 mM and 22.2 mM from a Lineweaver–Burk plot with the same enzyme derivative. To investigate the operational stability of the lipase, the three step lipolysis process was repeated by transferring the immobilized lipase to a substrate mixture. As a result, the percentange of conversion after usage decreased markedly.  相似文献   
5.
Molecular Biology Reports - Emamectin, a neurotoxic agent, is a semi-synthetic insecticide that belongs to the Avermectin family and is used against helmintic infections in the Salmonidae family....  相似文献   
6.
7.
Species- and tissue-specific defenses against the possibility of oxidative stress and lipid peroxidation were compared in adult fish, Oreochromis niloticus and Cyprinus carpio, exposed to 2,4-dichlorophenoxyacetic acid (2,4-D), azinphosmethyl and their combination for 96 h. Superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase activities were monitored in kidney, brain and gill. In all exposure groups there was a marked increase in SOD activity in gill tissues in both fish species, while it was at the control level in other tissues. The highest elevation of SOD activity by combined treatment was observed in C. carpio. Individual and combined treatments caused an elevation in catalase and GPx activities in kidney of C. carpio. Catalase activity was unaffected in brain of O. niloticus, while GPx activity was decreased after all treatments. Glutathione S-transferase (GST) activity was higher than the control levels in kidney of both fish exposed to pesticides. No significant changes were observed in malondialdehyde level in kidney and brain of C. carpio. Our results indicate that the toxicities of azinphosmethyl and 2,4-D may be related to oxidative stress. Also, the results show that SOD activity in gill and GST activity in kidney may be used as biomarkers for pollution monitoring and indicate that the activities of certain biomarkers in C. carpio are more sensitive to pesticides than those in O. niloticus.  相似文献   
8.
Undifferentiated and differentiated dendritic cells (uDC and dDC, respectively), derived from the bone marrow, were studied in vitro and in vivo. Ovalbumin (OVA) and two OVA-derived peptides binding to H-2K(b) and I-A(b), respectively, were used. Two IL-2 secreting T cell hybridomas specific for the OVA-derived epitopes were used in the in vitro read-out. The ability to cross-present the H-2K(b) binding OVA(257-264)-peptide (SIINFEKL) was restricted to dDC, which express CD11c(+), CD86(+), and MHC-II(+). In vitro, the antigenicity of SIINFEKL-loaded DC declined at a slower rate than that of OVA-pulsed DC. Moreover, SIINFEKL-loaded DC were up to 50 times more efficient than DC-pulsed with OVA-protein for generation of an H-2K(b)-restricted response. Immunization of mice with SIINFEKL-loaded DC resulted in a much stronger H-2K(b)-restricted response than immunization with OVA-pulsed DC. These data might have important implications for the choice of antigen source in the design of DC-based vaccines.  相似文献   
9.
10.
Several recent studies have revealed a wide role for nitric oxide (NO) in bone metabolism. Low doses of NO cause bone resorption, but higher doses of NO inhibit bone resorbing activity. Cytokines are potent stimulators of NO production. NO is a very short-lived molecules. It exists for only 6-10 s only before it is converted by oxygen and water into the end-products nitrates and nitrites. Osteoporosis is a metabolic bone disease, characterized by a decreased amount of bone and increased susceptibility to fracture. NO may be involved as a mediator of bone disease such as post-menopausal osteoporosis. Calcitonin is a peptide hormone that inhibits bone resorption. The function of calcitonin in some cells is often unclear. In this study 30 post-menopausal osteoporotic women of ages ranging between 55 and 59 years without systemic diseases and free of any drug therapy were included. Twenty of them, randomly chosen, were treated with calcium (500 mg day(-1))+calcitonin (nasal spray 100 U day(-1)) and the other 10 women (control group) were treated with calcium only. This treatment was applied for 6 months and NO values were measured in each of the two groups before and after treatment. Our findings demonstrate that NO regulates osteoclastic bone resorption activity in association with calcitonin.  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