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   26篇
  免费   1篇
  国内免费   1篇
电工技术   1篇
化学工业   2篇
轻工业   3篇
一般工业技术   9篇
冶金工业   9篇
自动化技术   4篇
  2023年   1篇
  2022年   1篇
  2019年   1篇
  2018年   2篇
  2013年   3篇
  2012年   4篇
  2008年   1篇
  2006年   1篇
  2005年   2篇
  2003年   1篇
  2002年   1篇
  1998年   2篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1994年   2篇
  1993年   1篇
  1981年   1篇
排序方式: 共有28条查询结果,搜索用时 640 毫秒
1.
The cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel has been identified in the cardiac muscle of a number of mammalian species, including humans. The goal of this study was to begin quantifying the structural requirements necessary for arylaminobenzoate block of the CFTR channel. The cardiac cAMP-dependent Cl- current (ICl) was measured using the whole-cell arrangement of the patch-clamp technique in guinea pig ventricular myocytes during stimulation of protein kinase A with forskolin. At drug concentrations below the IC50 value for channel block, reduction of ICl by the arylaminobenzoates occurred in a strongly voltage-dependent manner with preferential inhibition of the inward currents. At higher drug concentrations, block of both the inward and outward ICl was observed. Increasing the length of the carbon chain between the benzoate and phenyl rings of the arylaminobenzoates resulted in a marked increase in drug block of the channel, with IC50 values of 47, 17, and 4 microM for 2-benzylamino-5-nitro-benzoic acid, 5-nitro-2-(2-phenylethylamino)-benzoic acid, and 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), respectively. Increasing the carbon chain length further with the compound 5-nitro-2-(4-phenylbutylamino)-benzoic acid, caused no additional increase in the potency of drug block (IC50 = 4 microM). Inhibition of ICl by the arylaminobenzoates was modulated by the pH of the external solution; increasing the pH from 7.4 to 10.0 greatly weakened NPPB block, whereas decreasing the pH to 6.4 enhanced block. In addition, block of ICl was observed during intracellular dialysis of NPPB, and this action was not affected by raising the external pH.  相似文献   
2.
Several studies have addressed the possible importance of anti-epithelial cell antibodies in kidney transplantation using the A549 cell line as an in vitro model. In this paper we report our results using for the first time an enzyme-linked immunosorbent assay (ELISA) to detect the anti-A549 cell antibodies. Sera from 129 kidney transplant patients were tested for IgM anti-epithelial cell antibodies directed against the A549 cell line prior to transplantation; only three sera were positive (2.3%). 101 of these patients were then followed-up post-transplantation; sera were collected routinely at 2, 6 and 12 weeks and at the time of rejection episodes. All samples were also tested for cytomegalovirus (CMV) IgM antibodies. Sixteen patients developed anti-A549 IgM antibodies, and there was no correlation with acute graft rejection. Anti-epithelial antibodies showed no binding to sections of normal kidney or biopsies of rejected kidneys. Eleven patients were positive for anti-CMV IgM antibodies. In nine cases both IgM anti-A549 and IgM anti-CMV antibodies were found, which was a highly significant association (p < 0.001). Analysis of A549 cellular proteins by immunoblotting gave evidence for the presence of CMV polypeptides in the cell lysate. Electron-microscopic examination of A549 cell preparations revealed intracellular particles which were compatible in size with CMV. Polymerase chain reaction analysis confirmed the presence of a specific CMV DNA sequence in A549 cells of several batches from different sources. Our data strongly suggest that the A549 cell line used in several published reports is infected with CMV and that in the majority of cases the anti-A549 'anti-epithelial' antibodies found in renal transplant patients are anti-CMV antibodies.  相似文献   
3.
Older radiation detection equipment used in Health Physics operations suffers from unreliable and outdated electronics, even when the radiation detectors, shielding, and mechanical components are still serviceable. Upgrading these systems through relatively simple interfaces to modern personal computers can provide a cost-effective solution to extend the life of these systems and provide state-of-the-art options for computer control and automation. This paper outlines the basic needs and requirements for this type of upgrade and describes three projects at University of Missouri--Columbia that have used this approach.  相似文献   
4.
5.
Intraperitoneal and intracranial inoculation of herpes simplex virus type 2 (HSV 2) into BALB/cN and C57BL/6N mice was carried out to induce experimental myelitis. The myelitis was clearly observed in C57BL/6N mice following intraperitoneal inoculation. Within 24 hours before death, the mice showed urinary and rectal incontinence and paraplegia of the hind legs. Randomly distributed, severe necrosis was demonstrated in the spinal cord, mainly at the lower cord. In BALB/cN mice the clinical symptoms were not clearly observed, as the mice died shortly after their onset. Although spinal cord necrosis was more prominent in C57BL/6N mice than BALB/cN mice, brain necrosis was only found in the latter, and not in the former. Both strains of mouse showed marked nuclear pyknosis of the nerve cells and slight nuclear pyknosis of the astrocytes in the brain where HSV 2 antigen was demonstrated immunohistochemically. The antigen was also detected in the necrotic spinal cord. In contrast, intracranial inoculation of the virus into both strains did not cause myelitis. Spinal cord necrosis was not demonstrated and virus DNA was not detected, by PCR, in spinal cord samples. In the brain, however, the virus was demonstrated by both PCR and immunohistochemistry.  相似文献   
6.
Hexaaluminates and perovskites are two promising candidates for use in catalytic combustion applications. In the present study two hexaaluminates, LaMnAl11O19 and LaCoAl11O19, were compared with two perovskites, LaMnO3 and LaCoO3, with respect to their thermal stability and catalytic activity for combustion of methane and gasified biomass. The results showed that the hexaaluminates retained a much higher surface area even after calcination at 1200 °C compared to the perovskites. LaMnAl11O19 showed the highest catalytic activity of all catalysts. LaCoAl11O19 generally showed low activity. Of the two perovskites, LaCoO3 was the most active, and the initial test run the activity for biomass combustion were close to that one of LaMnAl11O19 even though its surface area was only one tenth of the hexaaluminate's. However, it was severely deactivated in the second test run. Similar deactivation but less severe was also found for the other catalyst.  相似文献   
7.
The kinetics of the footpad response of bacillus Calmette-Guérin (BCG)-infected mice to soluble BCG antigens were compared in two strains of mice with different degrees of susceptibility to Mycobacterium lepraemurium. For the first 21 days the responses of the 'high-resistance' C57BL and the 'low-resistance' BALB/c to the nonpathogenic BCG were similar to that produced when the pathogenic mycobacterium was used. After 4 weeks the kinetics of the BALB/c mice changed and resembled that of the C57BL mice. The change in kinetics was compared with circulating antimycobacterial antibody levels and the response of draining lymph node cells in the antigen-specific lymphocyte transformation test. A dissociation was found between the kinetics of the delayed footpad response and the lymphocyte transformation response. Since both strains of mice are equally resistant to BCG, it appears that the delayed footpad response cannot be used as an indicator of host resistance in all mycobacterial infections.  相似文献   
8.
9.
This paper presents a novel method of classifying transmission line shunt faults. Most algorithms employed for analyzing fault data require that the fault type be classified. The older fault-type classification algorithms are inefficient because they are not effective under certain operating conditions of the power system and may not be able to accurately select the faulted transmission line if the same fault recorder monitors multiple lines. The technique described in this paper has been proven to accurately identify all ten types of shunt faults that may occur in an electric power transmission system. The other advantage of this technique is that it can be used where multiple transmission lines are present. It is able to identify the faulted line even if secondary effects are recorded in the unfaulted lines.  相似文献   
10.
In this paper, a new image fusion algorithm based on non-subsampled contourlet transform (NSCT) is proposed for the fusion of multi-focus images. The selection of different subband coefficients obtained by the NSCT decomposition is critical to image fusion. So, in this paper, firstly, original images are decomposed into different frequency subband coefficients by NSCT. Secondly, the selection of the low-frequency subband coefficients and the bandpass directional subband coefficients is discussed in detail. For the selection of the low-frequency subband coefficients, the non-negative matrix factorization (NMF) method is adopted. For the selection of bandpass directional subband coefficients, a regional cross-gradient method that selects the coefficients according to the minimum of the regional cross-gradient is proposed. Finally, the fused image is obtained by performing the inverse NSCT on the combined coefficients. The experimental results show that the proposed fusion algorithm can achieve significant results in getting a new image where all parts are sharp.  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