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   37篇
  免费   2篇
电工技术   2篇
化学工业   12篇
轻工业   4篇
水利工程   1篇
无线电   4篇
一般工业技术   3篇
冶金工业   12篇
自动化技术   1篇
  2022年   2篇
  2020年   1篇
  2018年   1篇
  2017年   2篇
  2016年   2篇
  2014年   1篇
  2013年   2篇
  2012年   2篇
  2011年   4篇
  2010年   1篇
  2009年   2篇
  2007年   3篇
  2006年   2篇
  2005年   1篇
  2004年   1篇
  2002年   1篇
  2001年   1篇
  1999年   1篇
  1998年   5篇
  1997年   2篇
  1995年   1篇
  1988年   1篇
排序方式: 共有39条查询结果,搜索用时 15 毫秒
1.
The effluent from the anaerobic biological treatment of coffee wet processing wastewater (CWPW) contains a non-biodegradable compound that must be treated before it is discharged into a water source. In this paper, the wet hydrogen peroxide catalytic oxidation (WHPCO) process using Al-Ce-Fe-PILC catalysts was researched as a post-treatment system for CWPW and tested in a semi-batch reactor at atmospheric pressure and 25 °C. The Al-Ce-Fe-PILC achieved a high conversion rate of total phenolic compounds (70%) and mineralization to CO(2) (50%) after 5 h reaction time. The chemical oxygen demand (COD) of coffee processing wastewater after wet hydrogen peroxide catalytic oxidation was reduced in 66%. The combination of the two treatment methods, biological (developed by Cenicafé) and catalytic oxidation with Al-Ce-Fe-PILC, achieved a 97% reduction of COD in CWPW. Therefore, the WHPCO using Al-Ce-Fe-PILC catalysts is a viable alternative for the post-treatment of coffee processing wastewater.  相似文献   
2.
5'-Deoxy-5'-(methylthio)adenosine (MTA), a key by-product of polyamine biosynthesis, is cleaved by MTA phosphorylase and is salvaged as adenine and, through conversion of the ribose moiety, methionine. An analog of MTA, 5'-deoxy-5'-(hydroxyethylthio)adenosine (HETA), is a substrate for trypanosome MTA phosphorylase and is active in vitro and in vivo against Trypanosoma brucei brucei, an agent of bovine trypanosomiasis. In this study, HETA and three O-acylated HETA derivatives were examined for their activities against model infections of T. b. brucei and Trypanosoma brucei rhodesiense, the agent of East African sleeping sickness. HETA was curative (>60%) for infections caused by 5 of 11 clinical isolates of T. b. rhodesiense when it was given to mice at 200 mg/kg of body weight for 7 days as a continuous infusion in osmotic pumps. HETA at 150 to 200 mg/kg also extended the life spans of the mice infected with four additional isolates two- to fivefold. Di- and tri-O-acetylated derivatives of HETA also proved curative for the infections, while a tri-O-propionyl derivative, although also curative, was not as effective. This study indicates that substrate analogs of MTA should be given important consideration for development as novel chemotherapies against African trypanosomiasis.  相似文献   
3.
A collaborative study was carried out to determine the repeatability (error in each laboratory) and reproducibility (error between the different laboratories) of the fatty acid analysis of Iberian pig fat by gas chromatography. To do this, a comparison was made, in accordance with the ISO 5725-2 procedure, of the weight percentage (%) of the main fatty acids (C16:0, C18:0, C18:1 and C18:2) in 60 samples, determined by six laboratories. The results obtained for the relative standard deviation of the repeatability (0.56, 0.49, 0.29, and 0.69%) and for the relative standard deviation of the reproducibility (3.04, 3.54, 1.78 and 2.86%) show that the accuracy obtained is adequate for this analysis method, and in the same order or even higher than that obtained by other authors in similar samples. The differences between the results obtained on using two extraction methods of liquid fat from subcutaneous adipose tissue were recorded with no significant differences being observed between them.  相似文献   
4.
5.
Epigenetics, an inheritable phenomenon, which influences the expression of gene without altering the DNA sequence, offers a new perspective on the pathogenesis of hepatocellular carcinoma (HCC). Nonalcoholic steatohepatitis (NASH) is projected to account for a significant share of HCC incidence due to the growing prevalence of various metabolic disorders. One of the major molecular mechanisms involved in epigenetic regulation, post-translational histone modification seems to coordinate various aspects of NASH which will further progress to HCC. Mounting evidence suggests that the orchestrated events of cellular and nuclear changes during apoptosis can be regulated by histone modifications. This review focuses on the current advances in the study of acetylation-/methylation-mediated histone modification in apoptosis and the implication of these epigenetic regulations in HCC. The reversibility of epigenetic alterations and the agents that can target these alterations offers novel therapeutic approaches and strategies for drug development. Further molecular mechanistic studies are required to enhance information governing these epigenetic modulators, which will facilitate the design of more effective diagnosis and treatment options.  相似文献   
6.
Because an increase in biliary deoxycholate levels seems to be a risk factor for cholesterol gallstone formation, we determined the relationship between deoxycholate levels and levels of the pronucleating protein, immunoglobulin G (Ig) in human gallbladder bile. Patients with cholesterol gallstones had a higher concentration of biliary IgG compared with a pigmented stone group and control patients. This was associated with the simultaneous presence of two conditions in the cholesterol stone group, supersaturated bile and a high deoxycholate/cholate ratio. The other patient groups met only one of the two conditions. Next, animal studies were performed to determine if model biles mimicking the two conditions could affect IgG secretion by the gallbladder. Gallbladders were exposed in vivo and then in an Ussing chamber to model biles. The voltage clamp technique was used to monitor functional integrity of the preparation. Three different model biles were tested: (1) taurodeoxycholate (TDC), 80%; taurocholate (TC), 20%; and cholesterol saturation index (CSI), 1.2; (2) TDC, 20%; TC, 80%; and CSI, 1.2; and (3) TDC, 80%; TC, 20%; and CSI, 0.6. IgG concentrations became significantly higher in group 1 than in the other two groups. The concentration of mucous glycoprotein was also significantly greater in group 1 when compared with group 2. Plasma cells were increased in number in mucosal and submucosal layers in group 1. We conclude that cholesterol supersaturated model bile with high content of TDC induces gallbladder epithelial alterations, which increase the luminal concentration of IgG and mucous glycoprotein.  相似文献   
7.
A theoretical approach is presented for calculating the error involved in the solution of stochastic production costing problems using the method of cumulants. It is proposed to use this calculated error in an algorithm for obtaining an improved stochastic approximation of the equivalent-load-duration curve. The results show that of the three series that can be used for stochastic approximation, namely, the beta, the Gram-Charlier, and the Laguerre, the beta gives the best results. All three methods, however, give unacceptable errors in the approximation of the expected unserved energy. Another method is proposed that approximates the error between the beta curve and the actual curve using the Fourier-Chebyshev expansion, which is used to develop a better stochastic approximation. Results obtained using practical system data indicate that this method gives much better results than the three methods discussed above  相似文献   
8.
Although tremendous efforts have been made on targeted drug delivery systems, current therapy outcomes still suffer from low circulating time and limited targeting efficiency. The integration of cell‐mediated drug delivery and theranostic nanomedicine can potentially improve cancer management in both therapeutic and diagnostic applications. By taking advantage of innate immune cell's ability to target tumor cells, the authors develop a novel drug delivery system by using macrophages as both nanoparticle (NP) carriers and navigators to achieve cancer‐specific drug delivery. Theranostic NPs are fabricated from a unique polymer, biodegradable photoluminescent poly (lactic acid) (BPLP‐PLA), which possesses strong fluorescence, biodegradability, and cytocompatibility. In order to minimize the toxicity of cancer drugs to immune cells and other healthy cells, an anti‐BRAF V600E mutant melanoma specific drug (PLX4032) is loaded into BPLP‐PLA nanoparticles. Muramyl tripeptide is also conjugated onto the nanoparticles to improve the nanoparticle loading efficiency. The resulting nanoparticles are internalized within macrophages, which are tracked via the intrinsic fluorescence of BPLP‐PLA. Macrophages carrying nanoparticles deliver drugs to melanoma cells via cell–cell binding. Pharmacological studies also indicate that the PLX4032 loaded nanoparticles effectively kill melanoma cells. The “self‐powered” immune cell‐mediated drug delivery system demonstrates a potentially significant advancement in targeted theranostic cancer nanotechnologies.  相似文献   
9.
Acacia glomerosa, Benth. (Vulgares Series) exudates a clear gum which produces gels easily. The physico-chemical data and sugar composition are very close to gum arabic from Acacia senegal, except that A. glomerosa gum contains a high nitrogen content. A series of degraded products was prepared by acid hydrolysis and Smith-degradation. The characterization of the degraded products by partial hydrolysis, sugar composition and by the application of uni- and bidimensional spectroscopy led to know interesting structural features of the polysaccharide isolated from A. glomerosa gum. This polysaccharide, as that from A. senegal gum, consists of 1,3-β- -galactopyranosyl backbone. There are side-chains of 1,3-β- -galactopyranosyl oligosaccharides attached to position six of the galactan main chain. Arabinose (furanosyl and pyranosyl) residues may be up to four units long because it was necessary to prepare four polysaccharides to remove them from the gum structure. Uronic acid residues were difficult to remove as has been observed in other Acacia gums.  相似文献   
10.
The hitherto unknown 2,6-hexadecadiynoic acid, 2,6-nonadecadiynoic acid, and 2,9-hexadecadiynoic acid were synthesized in two steps and in 11–18% overall yields starting from either 1,5-hexadiyne or 1,8-nonadiyne. Among all the compounds 2,6-hexadecadiynoic acid displayed the best overall antifungal activity against both the fluconazole-resistant Candida albicans strains ATCC 14053 and ATCC 60193, with a minimum inhibitory concentration (MIC of 11 μM), and against Cryptococcus neoformans ATCC 66031 (MIC<5.7 μM). 2,9-Hexadecadiynoic acid did not display any significant cytotoxicity against the fluconazole-resistant C. albicans strains, but it showed fungitoxicity against C. neoformans ATCC 66031 with a MIC value of <5.8 μM. Other FA, such as 2-hexadecynoic acid, 5-hexadecynoic acid, 9-hexadecynoic acid, and 6-nonadecynoic acid were also synthesized and their antifungal activities compared with those of the novel acetylenic FA, 2-Hexadecynoic acid, a known antifungal FA, exhibited the best antifungal activity (MIC=9.4 μM) against the fluconazole-resistant C, albicans ATCC 14053 strain, but it showed a MIC value of only 100 μM against C. albicans ATCC 60193. 2,6-Hexadecadiynoic acid and 2-hexadecynoic acid also displayed a MIC of 140–145 μM toward Mycobacterium tuberculosis H37Rv in Middlebrook 7H12 medium. In conclusion, 2,6-hexadecadiynoic acid exhibited the best fungitoxicity profile compared with other analogues. This diynoic FA has the potential to be further evaluated for use in topical antifungal formulations.  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