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   12篇
  免费   0篇
化学工业   2篇
机械仪表   1篇
水利工程   2篇
无线电   2篇
一般工业技术   2篇
冶金工业   2篇
自动化技术   1篇
  2022年   1篇
  2016年   2篇
  2009年   1篇
  2007年   3篇
  2006年   1篇
  2004年   1篇
  2003年   1篇
  1998年   1篇
  1996年   1篇
排序方式: 共有12条查询结果,搜索用时 140 毫秒
1.
We have studied the prevalence and the serological profile of HBV, HCV, HDV and HIV infections in 137 Italian subjects addicted to the intravenous use of heroine and correlated the virological findings with sexual behaviour. HBV and HCV viremia were also measured in 114 patients. Anti-HCV was detected in 81% of the addicts, and one or more markers of HBV infection were detected in 62.8% (4.4% were carriers of HBsAg, 58.4% had evidence of past HBV infection and 13.1% of the latter also had HDV markers). Anti-HIV was positive in 23.4%; 26% of those positive for anti-HCV and 4.6% of those positive for HBV markers had no other viral marker: none had only anti-HIV. HBV-DNA was negative in the carriers of HBsAg, and HCV-RNA was not detected in any of the HBsAg carriers who also had circulating anti-HCV. Overall, 34% of the anti-HCV positive addicts had HCV-RNA in their blood. The prevalence of the virus infection correlated with the duration of drug addiction but not with sexual behaviour, and sexual behaviour did not influence the acquisition of any virus. HCV infection was most frequent and probably the first infection to occur, but exposure to HBV was also common despite a low rate of HBsAg carriage. The prevalence of HDV infection was high (50%) in the HBsAg carriers, while the overall prevalence of HIV was lower (23%) than expected. Lack of HBV-DNA and HCV-RNA in carriers of HBV with anti-HCV in serum may indicate that HBV and HCV mutually inhibit their own replication.  相似文献   
2.
The transient suppression of muscle contraction during the cutaneous silent period (CSP) could be produced either through postsynaptic inhibition of motoneurons or through presynaptic inhibition of the excitatory inputs to motoneurons that sustain voluntary contraction. We sought to delineate the mechanisms underlying the CSP in hand muscles by measuring changes in H-reflexes and motor-evoked potentials (MEPs) produced by transcranial magnetic stimulation (TMS) during the CSP in 10 healthy volunteers. H-reflexes and MEPs both measure the excitability of the motoneuron pool and activate similar subpopulations of motoneurons through different pathways. Inhibition of H-reflexes and MEPs of similar size was maximal at the midpoint of the CSP and gradually returned to baseline. The similar time course of recovery suggests that the H-reflex and MEP are affected by inhibition at a common site, most likely postsynaptic inhibition of the motoneurons.  相似文献   
3.
Due to the enormous amount of information available on the Internet, extracting and classifying it has become one of the most important tasks. This principle is valid also while searching for scientific publications. This paper describes a system able to retrieve scientific publications from the Web throughout a text categorization process. To this end, a generic multiagent architecture has been customized according to the requirements imposed by the specific task. Experiments have been performed on publications extracted from BMC Bioinformatics and PubMed digital archives.  相似文献   
4.
The feasibility of an autotrophic denitrification process in an activated sludge reactor, using sulphide as the electron donor, was tested for simultaneous denitrification and sulphide removal. The reactor was operated at nitrate (N) to sulphide (S) ratios between 0.5 and 0.9 to evaluate their effect on the N-removal efficiency, the S-removal efficiency and the product formation during anoxic oxidation of sulphide. One hundred per cent removal of both nitrate and sulphide was achieved at a NLR of 7.96 mmol N-L(-1) x d(-1) (111.44 mg NO3- -N x L(-1) x d(-1)) and at a N/S ratio of 0.89 with complete oxidation of sulphide to sulphate. The oxygen level in the reactor (10%) was found to influence the N-removal efficiency by inhibiting the denitrification process. Moreover, chemical (or biological) oxidation of sulphide with oxygen occurred, resulting in a loss of the electron donor. FISH analysis was carried out to study the microbial population in the system.  相似文献   
5.
6.
Chlorinated compounds are widely used in agricultural applications where they are employed as components of pesticides; this leads often to pollution of groundwater near to agricultural sites, with serious effects for human health. The aim of the present study was the development of a membrane bioreactor, a new and effective water treatment technology, for the bioremediation of water polluted by 1,2-dichloroethane, 1,2-dichlorobenzene and 2-chlorophenol. Before starting-up the MBR system, a biomass was acclimated, to simultaneously degrade the three chlorinated compounds; then the acclimated biomass was inoculated into the MBR. The results showed a higher removal rate for 1,2-dichloroethane than for 1,2-dichlorobenzene; besides, the presence of 1,2-dichlorobenzene together with 1,2-dichloroethane decreased 1,2-dichloroethane specific removal rate. 2-chlorophenol was degraded only in presence of phenol as co-substrate, and the presence of phenol and 2-chlorophenol decreased 1,2-dichloroethane specific removal rate of approximately eight times, while 1,2-dichlorobenzene specific removal rate was not affected.  相似文献   
7.
BACKGROUND: This study explores an alternative process for the abatement and/or desulfurization of H2S and volatile organic sulfur compounds (VOSC) containing waste streams, which employs a silicone‐based membrane to simultaneously remove H2S and VOSC. An extractive membrane reactor allows the selective withdrawal of VOSC and H2S simultaneously from the waste stream, while preventing direct contact between the waste stream and the absorbing solution and/or the biological treatment system. The influence of the sulfur compounds, membrane characteristics, extractant and pH was studied. RESULTS: Sulfide and the VOCS studied, i.e. methanethiol (MT), ethanethiol (ET) and dimethylsulfide (DMS) were removed from the synthetic wastewater using a silicone rubber membrane. Methanethiol showed the highest (8.72 × 10?6 m s?1) overall mass transfer coefficient (kov) and sulfide the lowest kov value (1.23 × 10?6 m s?1). Adsorption of the VOCS into the silicone membrane reduced the overall mass transfer coefficient. The kov when using Fe(III)EDTA? as extractant (5.81 × 10?7 m s?1) for sulfide extraction was one order of magnitude lower than with anaerobic water (2.54 × 10?6 m s?1). On the other hand, the sulfide removal efficiency with Fe(III)EDTA? was higher (84%) compared with anaerobic water (60%) as extractant. An additional mass transfer resistance was formed by elemental sulfur which remained attached to the membrane surface. CONCLUSIONS: Extraction of sulfide and VOCS from a synthetic wastewater solution through a silicone rubber membrane is a feasible process as alternative to the techniques developed to treat VOSC emissions. Optimizing the aqueous absorption liquid can increase the efficiency of extraction based processes. Copyright © 2008 Society of Chemical Industry  相似文献   
8.
This paper proposes a novel approach for admission control in traffic engineered data networks, which applies at network edges by means of dynamic thresholds evaluated on the basis of network status. The proposed method is described with focus on IP/MPLS networks, but it actually applies as well to a variety of scenarios, such as ATM or generalized MPLS. The proposed solution allows more efficient usage of network resources, especially at medium/high load, and increased robustness of the network.  相似文献   
9.
Sorting is a very important task in computer science and becomes a critical operation for programs making heavy use of sorting algorithms. General‐purpose computing has been successfully used on Graphics Processing Units (GPUs) to parallelize some sorting algorithms. Two GPU‐based implementations of the quicksort were presented in literature: the GPU‐quicksort, a compute‐unified device architecture (CUDA) iterative implementation, and the CUDA dynamic parallel (CDP) quicksort, a recursive implementation provided by NVIDIA Corporation. We propose CUDA‐quicksort an iterative GPU‐based implementation of the sorting algorithm. CUDA‐quicksort has been designed starting from GPU‐quicksort. Unlike GPU‐quicksort, it uses atomic primitives to perform inter‐block communications while ensuring an optimized access to the GPU memory. Experiments performed on six sorting benchmark distributions show that CUDA‐quicksort is up to four times faster than GPU‐quicksort and up to three times faster than CDP‐quicksort. An in‐depth analysis of the performance between CUDA‐quicksort and GPU‐quicksort shows that the main improvement is related to the optimized GPU memory access rather than to the use of atomic primitives. Moreover, in order to assess the advantages of using the CUDA dynamic parallelism, we implemented a recursive version of the CUDA‐quicksort. Experimental results show that CUDA‐quicksort is faster than the CDP‐quicksort provided by NVIDIA, with better performance achieved using the iterative implementation. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
10.
Histone deacetylase (HDAC) inhibitors are novel chemotherapy agents with potential utility in the treatment of neuroblastoma, the most frequent solid tumor of childhood. Previous studies have shown that the exposure of human neuroblastoma cells to some HDAC inhibitors enhanced the expression of the common neurotrophin receptor p75NTR. In the present study we investigated whether the upregulation of p75NTR could be exploited to render neuroblastoma cells susceptible to the cytotoxic action of an anti-p75NTR antibody conjugated to the toxin saporin-S6 (p75IgG-Sap). We found that two well-characterized HDAC inhibitors, valproic acid (VPA) and entinostat, were able to induce a strong expression of p75NTR in different human neuroblastoma cell lines but not in other cells, with entinostat, displaying a greater efficacy than VPA. Cell pretreatment with entinostat enhanced p75NTR internalization and intracellular saporin-S6 delivery following p75IgG-Sap exposure. The addition of p75IgG-Sap had no effect on vehicle-pretreated cells but potentiated the apoptotic cell death that was induced by entinostat. In three-dimensional neuroblastoma cell cultures, the subsequent treatment with p75IgG-Sap enhanced the inhibition of spheroid growth and the impairment of cell viability that was produced by entinostat. In athymic mice bearing neuroblastoma xenografts, chronic treatment with entinostat increased the expression of p75NTR in tumors but not in liver, kidney, heart, and cerebellum. The administration of p75IgG-Sap induced apoptosis only in tumors of mice that were pretreated with entinostat. These findings define a novel experimental strategy to selectively eliminate neuroblastoma cells based on the sequential treatment with entinostat and a toxin-conjugated anti-p75NTR antibody.  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