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   67篇
  免费   0篇
化学工业   33篇
机械仪表   1篇
建筑科学   8篇
能源动力   6篇
轻工业   6篇
无线电   1篇
一般工业技术   6篇
自动化技术   6篇
  2023年   1篇
  2022年   4篇
  2021年   2篇
  2020年   1篇
  2018年   2篇
  2017年   4篇
  2016年   2篇
  2015年   1篇
  2013年   4篇
  2012年   4篇
  2011年   6篇
  2010年   4篇
  2009年   6篇
  2008年   6篇
  2007年   4篇
  2006年   4篇
  2005年   1篇
  2003年   1篇
  2001年   2篇
  1993年   1篇
  1989年   1篇
  1985年   2篇
  1981年   4篇
排序方式: 共有67条查询结果,搜索用时 15 毫秒
21.
The interaction between chloride and thiourea in copper electrodeposition in a sulfate-plating bath was investigated. The sole addition of thiourea to the bath increased the polarization of the electrode potential during copper deposition, leading to very fine and smoothly structured deposit but with microscopic nodules distributed over the surface. When chloride was added to a plating solution containing thiourea, the copper deposition mechanism was changed, showing a depolarization of the electrode potential, and the copper deposits were found to have a relatively rougher microstructure, but without the formation of microscopic nodules. However, rough deposit surfaces having no distinct pattern were formed at the macroscopic scale. Observations of roughening evolution show that the rough surface was initiated from small holes formed across the deposit surface during the initial stage of deposition that eventually developed into visibly rough deposits. The copper deposition inside these holes and at other areas was expected to undergo different deposition mechanisms. Copper deposition in the areas that ultimately developed into holes was almost totally inhibited by the thiourea–Cu(I)–chloride complex film, not just in the grain growth process, but over practically the entire electrodeposition process. Conversely, copper deposition occurred in other areas under conditions where nucleation proceeded, but grain growth was inhibited to produce a fine, homogeneous microstructure. An uneven deposit surface that had different microscopic structures in different areas was then formed. The structure of the thiourea–Cu(I)–chloride film was strongly affected by the current density and appeared to break down completely if sufficiently high current density was applied to yield a fine and homogeneous microstructure that was also macroscopically smooth.  相似文献   
22.
Renal cyst expansion in polycystic kidney disease (PKD) involves abnormalities in both cyst-lining-cell proliferation and fluid accumulation. Suppression of these processes may retard the progression of PKD. Evidence suggests that the activation of 5′ AMP-activated protein kinase (AMPK) inhibits cystic fibrosis transmembrane conductance regulator (CFTR)–mediated chloride secretion, leading to reduced progression of PKD. Here we investigated the pharmacological effects of panduratin A, a bioactive compound known as an AMPK activator, on CFTR-mediated chloride secretion and renal cyst development using in vitro and animal models of PKD. We demonstrated that AMPK was activated in immortalized normal renal cells and autosomal dominant polycystic kidney disease (ADPKD) cells following treatment with panduratin A. Treatment with panduratin A reduced the number of renal cyst colonies corresponding with a decrease in cell proliferation and phosphorylated p70/S6K, a downstream target of mTOR signaling. Additionally, panduratin A slowed cyst expansion via inhibition of the protein expression and transport function of CFTR. In heterozygous Han:Sprague–Dawley (Cy/+) rats, an animal model of PKD, intraperitoneal administration of panduratin A (25 mg/kg BW) for 5 weeks significantly decreased the kidney weight per body weight ratios and the cystic index. Panduratin A also reduced collagen deposition in renal tissue. Intraperitoneal administration of panduratin A caused abdominal bleeding and reduced body weight. However, 25 mg/kg BW of panduratin A via oral administration in the PCK rats, another non-orthologous PKD model, showed a significant decrease in the cystic index without severe adverse effects, indicating that the route of administration is critical in preventing adverse effects while still slowing disease progression. These findings reveal that panduratin A might hold therapeutic properties for the treatment of PKD.  相似文献   
23.
24.
The feasibility of the electrochemical conversion of glycerol to alternative, more valuable compounds was evaluated with platinum electrode under galvanostatic conditions. The results indicated a potentially good feasibility of reforming glycerol by electrolysis, particularly under strong acidic conditions (pH 1). Indeed, under controlled conditions at pH 1, various commercially valuable compounds, such as propanediol, glycidol, and 2-propenol, amongst others, were produced. The mechanism for the generation of the key compounds is proposed.  相似文献   
25.
European Journal of Wood and Wood Products - This paper investigated the impact of microwave-assisted drying on the energy consumption, drying rate, surface temperature, drying time, static bending...  相似文献   
26.
ABSTRACT

The paper reports a study of chromosome abnormalities (CA/s) in the Monopterus albus near a gold mine area compared to a non-affected area. The arsenic (As) concentrations were determined in the water, sediment and M. albus muscles. The average concentrations of As in the water and sediment samples near the gold mine were higher than allowable by Thailand’s water quality standards. The average concentrations of As in the M. albus samples were lower than the standards. The diploid chromosome number of M. albus in both areas was 2n = 24. The percentage of CA of M. albus in the gold mine area was higher than in the non-affected area. Seven types of CA were single chromatid gap (SCG), fragmentation (F), sister chromatid gap, single chromatid breaks, deletion, sister chromatid fragmentation and centric fusion. In the affected area, the most common CAs in the samples were SCG and F. The specific CA in M. albus samples was SCG on chromosome pair 1. It can be concluded that As contamination caused structural CA, but did not affect the diploid chromosome number in the Asian swamp eel from the gold mine area. The accumulation of As in M. albus has potential effects on human health in consumers of M. albus from this contaminated area.  相似文献   
27.
Modelling of steel fiber-reinforced concrete under multi-axial loads   总被引:2,自引:0,他引:2  
Fifty-four plain concrete and steel fiber-reinforced concrete (SFRC) plate specimens containing 0.5%, 1.0% and 1.5% of hooked fibers were tested under biaxial compression. The experimental results obtained were used to verify a failure surface developed earlier by the authors for SFRC under multi-axial loads. An equation has also been proposed in this study to predict the strain at failure for SFRC under multi-axial loads, εci. The proposed failure criterion and equation to predict εci were incorporated into a constitutive model in a well-established finite-element software, ABAQUS. Experiments of SFRC plate specimens under multi-axial loads and beams under two-point load were modeled to illustrate the application of the failure surface to SFRC under varying load conditions. Good agreement between analytical and experimental results is observed.  相似文献   
28.
Mevinolin, citrinin and pigments of adlay angkak fermented by Monascus sp   总被引:1,自引:0,他引:1  
Adlay angkak a new developed product from an adlay substrate fermented by Monascus fungi can be used both as a natural coloring and a dietary supplement. However, not only useful secondary metabolites such as mevinolin and pigments are produced; the fungi also produce toxin substance called citrinin. This study conducted the cultivation of M. purpureus (ATCC 16365, BCC 6131, DMKU and FTCMU) and M. ruber TISTR 3006 on the adlay substrate for mevinolin, citrinin, pigments and glucosamine synthesis at room temperature (32-35 degrees C) for 28 days. The results elucidated that glucosamine levels expressed as the mold growth in solid-state fermentation corresponded as a relatively reliable indicator to the mevinolin, citrinin and pigments production. M. purpureus DMKU produced the lowest citrinin content of 0.26 ppm and the highest mevinolin content of 25.03 ppm with pigment concentrations expressed by absorbance at wavelengths of 400, 470 and 500 nm for yellow, orange and red pigments of 9.76, 3.03 and 3.43 units respectively and moisture content and pH of 83.51% and 6.54 respectively. This study suggested that M. purpureus DMKU has a potential for the production of adlay angkak within an authorized citrinin level.  相似文献   
29.
A method is presented for solving by hand structural systems comprising frames and shear walls coupled together through floor slabs. The coupled system is viewed as a shear-flexure cantilever which resists the lateral loads by its combined actions and the coupled governing equations are solved by the Galerkin technique. The contribution of each term from the assumed displacement field is uncoupled by choosing appropriate admissible functions. This uncoupling condition is valid when the structure is uniform throughout the height.  相似文献   
30.
We construct cooperative diversity coding schemes that mitigate the effects of symbol asynchronicity among network users. We do so by modifying, at the expense of implementation practicality, the signaling complexity of well behaved existing schemes. The modification allows the same good performance (DMT optimality) in the presence of synchronicity, and almost-surely permits full-diversity gains for any event of symbol asynchronicity. This work was in part carried out while Petros Elia was at the University of Southern California. This research is supported in part by NSF-ITR CCR-0326628.  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