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   23篇
  免费   0篇
化学工业   1篇
金属工艺   1篇
建筑科学   1篇
能源动力   2篇
轻工业   1篇
无线电   1篇
一般工业技术   11篇
冶金工业   4篇
自动化技术   1篇
  2014年   1篇
  2013年   1篇
  2012年   1篇
  2011年   2篇
  2009年   3篇
  2008年   2篇
  2007年   1篇
  2006年   1篇
  2005年   1篇
  2004年   2篇
  2003年   1篇
  1998年   3篇
  1994年   1篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
排序方式: 共有23条查询结果,搜索用时 406 毫秒
1.
The dose of cells expressing the surface antigen CD34 (CD34+) has been shown to be a reliable predictor of the time to engraftment following transplantation of PBPC to support high-dose chemotherapy. However, evaluation of rare cells is complicated by a number of factors, including the variability in operator and technical procedures. Recently, Becton Dickinson Immunocytometry Systems introduced a new CD34+ cell analysis system, the ProCOUNT cell enumeration kit, which automates the analysis of CD34+ cells and minimizes the variabilities of this procedure. We have evaluated the ProCOUNT system in comparison to a standard CD34 cell analysis (based on the Milan approach) using leukapheresis products from patients and normal donors mobilized with chemotherapy plus recombinant human G-CSF (rhG-CSF) or with rhG-CSF alone. In addition, we compared these analyses using CD34+ cell-selected mobilized leukapheresis products with purities of 75% or greater. The standard CD34 cell analysis methodology quantitated the frequency of cells identified as CD45+, low side scatter, and CD34+. A high correlation coefficient was obtained between the ProCOUNT methodology and the standard CD34 cell analysis methodology for cells obtained from leukapheresis products mobilized with chemotherapy plus rhG-CSF (r = 0.98), rhG-CSF alone (r = 0.96), and CD34+-selected mobilized leukapheresis products (r = 0.83). A comparison was also made between technicians using both analysis methods. Whereas the correlation coefficient between two technicians using the standard methodology was r = 0.77, the correlation coefficient was much higher when using ProCOUNT (r = 0.99). These data demonstrate that the use of ProCOUNT is associated with less variability between data analyzed by different operators. Also, ProCOUNT is consistent with existing CD34+ cellular analysis methodologies. An additional advantage is the ability to determine the absolute concentration of CD34+ cells, thereby allowing calculation of total CD34+ cell numbers without using WBC counts, which also have inherent errors. The ProCOUNT system provides an automated analysis procedure that minimizes the variables in CD34+ cell analysis and may be useful for standardization of methodology between laboratories.  相似文献   
2.
In this paper, a real-time monitoring system of tool breakage, which measures the cutting torque from the spindle motor current, is described. The system uses an auto-regressive (AR)-model which is adapted for the measured signal using the Kalman filtering technique. The tool breakage is detected by monitoring the residual, that is, the deviation of the observed signal from the estimated value obtained by the AR-model. Additional processing of the residual is introduced to discriminate the signature of tool breakage from the effect caused by the marked change in the cutting condition. To reduce the computation time, the fast calculation algorithm is adopted for estimating the coefficient vector of the AR-model. The monitoring experiment has proven the effectiveness of the system in a milling operation.  相似文献   
3.
This report describes the results and operating status of ground lifetime testing and achievements on orbit of coolers for space use. Ground lifetime tests of coolers of three types were conducted to demonstrate their long life and reliability. Three single-stage Stirling coolers were tested for 89,016, 71,871 and 68,273 h from 1998, a two-stage Stirling cooler was tested for 72,906 h, and a 4-K class cooler with a two-stage Stirling cooler and a Joule–Thomson cooler was tested for over 2.5 years. After lifetime tests were completed, a few coolers were investigated to determine the cause of the cooling performance degradation. Additionally, the filled gas of the coolers was analyzed. These coolers have shown good results on orbit. Three single-stage Stirling coolers were carried on the X-ray astronomical satellite “SUZAKU” (launched in July 2005), Japanese lunar polar orbiter “KAGUYA” (launched in September 2007), and the Japanese Venus Climate Orbiter “AKATSUKI” (launched in June 2010). Two units of a two-stage Stirling cooler were carried on the infrared astronomical satellite “AKARI” launched in February 2006. A 4-K class cooler was carried on the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) aboard the Japanese Experiment Module (JEM) of the International Space Station (ISS). SMILES was launched in September 2009.  相似文献   
4.
The control of the growth of a Pb-based alloy grid is very important for extending the life of a lead-acid battery. In this study, the creep behavior of pure Pb was investigated in air, in a highly concentrated H2SO4 solution, and in a highly concentrated H2SO4 solution with the intermittent electrifying to the specimen electrode, which simulated the discharge-charge process of the lead-acid battery, in order to obtain the fundamental knowledge about the growth of the Pb-based alloy grid. The growth or the creep of pure Pb in the stress range of 4.0-6.0 MPa was advanced by a dislocation creep mechanism. The creep rate in a 4.5 kmol m−3 H2SO4 solution was also accelerated by the electrifying to the electrode. This suggests that the acceleration of the creep rate is closely related to the release of dislocations near the specimen surface by the electrifying.  相似文献   
5.
This paper examines a new method of evaluating the stability of a rock slope using a remotely positioned LDV (laser Doppler vibrometer). We conducted an experiment using physical models and performed a numerical analysis to evaluate the new method. The physical model included: (l) concrete blocks on an artificial soil slope with two block sizes and three slopes; (2) concrete blocks bonded to the concrete base with different contact area. The LDV measurements agreed with conventional seismometer measurements. The dominant frequency of the blocks varied with the stability and dominant frequency and the amplitude varied with the block size. The numerical model was used to examine a concrete block adhered to a concrete base with different contact areas. The dominant frequency of the blocks determined using the numerical model agreed with those obtained from the physical experiments. We analyzed different sized blocks to examine the scaling effects. The dominant frequency of the blocks was inversely related to the block size. These results demonstrated the effectiveness of LDV for evaluating the stability of rock slopes and cleared the block size scaling effects.  相似文献   
6.
We investigated the influence of alcohol and the low protein diet upon rat pancreas. Rats were separated in four groups, 1) Control diet group (Cont), 2) Alcohol diet group (Al), 3) Low protein diet group (Lp), 4) Low protein and alcohol diet group (Lp+Al). They were fed on isocaloric liquid diet compulsorily through the gastric tube. They were sacrificed 3, 6, 12 weeks after. By the light microscopic observation on the rat pancreas which were fed for 12 weeks, lipid droplets in the acinar cells were observed in all groups other than Cont. Apoptosis was founded in Lp and Lp+Al groups. Protein plugs were observed in all groups, and no relation was found between the plugs and the location of the injured acinar cells. By the electromicroscopic observation, in Lp+Al group, acinar cells were typically injured (ER dilation, atrophic nuclei, mitochondria degeneration, etc.) and mesenchymal cells appeared among acinar cells. These results suggest that alcohol causes pancreatic acinar cell injury directly, and relative low protein diet helps to turn it worse.  相似文献   
7.
Quantitative proteome analysis has become a versatile tool to understand biological functions. Although stable isotope labeling is the most reliable method for quantitative mass spectrometry, preparation of isotope-labeled compounds is time-consuming and expensive. Simple label-free approaches have been introduced, but intensity-based quantitation without standards is not generally accepted as reliable, especially for small molecules. We have developed a novel label-free quantitative proteome analysis using pseudo internal standards (PISs). This idea was derived from northern blotting analysis, in which housekeeping genes are used as standards to normalize and compare target gene expression levels in different samples. In many proteomics studies, most proteins do not change their expression levels under different conditions, and therefore, these proteins can be employed as pseudo internal standards. This new approach is simple and does not require additional standards or labeling reagents. The PIS method represents a novel approach for mass spectrometry-based comprehensive quantitatitation and may also be applicable to quantitative metabolome analysis.  相似文献   
8.
L ‐Azetidine‐2‐carboxylic acid (AZC) is a toxic four‐membered ring analogue of L ‐proline that is transported into cells by proline transporters. AZC and L ‐proline in the cells are competitively incorporated into nascent proteins. When AZC is present in a minimum medium, misfolded proteins are synthesized in the cells, thereby inhibiting cell growth. The MPR1 gene has been isolated from the budding yeast Saccharomyces cerevisiae Σ1278b as a multicopy suppressor of AZC‐induced growth inhibition. MPR1 encodes a novel acetyltransferase that detoxifies AZC via N‐acetylation. Since MPR1 is absent in the laboratory strain of S. cerevisiae S288C, it could be a positive selection marker that confers AZC resistance in the S288C background strains. To examine the usefulness of MPR1, we constructed some plasmid vectors that harboured MPR1 under the control of various promoters and introduced them into the S288C‐derived strains. The expression of MPR1 conferred AZC resistance that was largely dependent on the expression level of MPR1. In an additional experiment, the galactose‐inducible MPR1 and ppr1+, the fission yeast Schizosaccharomyces pombe homologue of MPR1, were used for gene disruption by homologous recombination, and here AZC‐resistant colonies were also successfully selected. We concluded that our MPR1–AZC system provides a powerful tool for yeast transformation. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
9.
We investigated the formation of CuO or Cu2O nanoparticles in the thick polyimide films by oxidizing Cu nanoparticles at various temperatures during the post heat-treatment. Cu nanoparticles of 4-5 nm in diameter were initially formed in the polyimide film by the reaction between a Cu film and a polyimide precursor, polyamic acid, and a following thermal curing in a reducing atmosphere. After the subsequent post heat-treatments in oxidizing atmospheres, X-ray diffraction patterns revealed that initial metallic Cu nanoparticles were transformed to Cu2O or CuO nanoparticles depending on the temperature during the post heat-treatment. Cu nanoparticles were oxidized to Cu2O during the post heat-treatment at low temperature while Cu nanoparticles were oxidized to CuO during the post heat-treatment at high temperature. Cross-sectional TEM studies showed that about 4.7 nm sized Cu2O nanoparticles or 4.7-5.2 nm sized CuO nanoparticles were fabricated in a thick polyimide film depending on the post heat-treatment condition. In the optical absorption measurements, the absorption peak from surface plasmon resonance of Cu nanoparticles disappeared during the post heat-treatment in an oxidizing atmosphere.  相似文献   
10.
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