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   20篇
  免费   1篇
化学   12篇
数学   8篇
物理学   1篇
  2019年   1篇
  2017年   1篇
  2016年   1篇
  2013年   1篇
  2006年   1篇
  1998年   1篇
  1994年   1篇
  1993年   3篇
  1992年   1篇
  1991年   2篇
  1990年   1篇
  1989年   3篇
  1986年   1篇
  1978年   1篇
  1975年   1篇
  1974年   1篇
排序方式: 共有21条查询结果,搜索用时 15 毫秒
1.
2.
3.
Poly(ethylene glycol) (PEG 4000) and bovine serum albumin (BSA) were investigated with the purpose of evaluating their influence on enzymatic hydrolysis of sugarcane bagasse. Effects of these supplements were assayed for different enzymatic cocktails (Trichoderma harzianum and Penicillium funiculosum) that acted on lignocellulosic material submitted to different pretreatment methods with varying solid (25 and 100 g/L) and protein (7.5 and 20 mg/g cellulose) loadings. The highest levels of glucose release were achieved using partially delignified cellulignin as substrate, along with the T. harzianum cocktail: increases of 14 and 18 % for 25 g/L solid loadings and of 33 and 43 % for 100 g/L solid loadings were reached for BSA and PEG supplementation, respectively. Addition of these supplements could maintain hydrolysis yield even for higher solid loadings, but for higher enzymatic cocktail protein loadings, increases in glucose release were not observed. Results indicate that synergism might occur among these additives and cellulase and xylanases. The use of these supplements, besides depending on factors such as pretreatment method of sugarcane bagasse, enzymatic cocktails composition, and solid and protein loadings, may not always lead to positive effects on the hydrolysis of lignocellulosic material, making it necessary further statistical studies, according to process conditions.  相似文献   
4.
5.
6.
Anthracyclines are a well‐known chemical class produced by actinobacteria used effectively in cancer treatment; however, these compounds are usually produced in few amounts because of being toxic against their producers. In this work, we successfully explored the mass spectrometry versatility to detect 18 anthracyclines in microbial crude extract. From collision‐induced dissociation and nuclear magnetic resonance spectra, we proposed structures for five new and identified three more anthracyclines already described in the literature, nocardicyclins A and B and nothramicin. One new compound 8 (4‐[4‐(dimethylamino)‐5‐hydroxy‐4,6‐dimethyloxan‐2‐yl]oxy‐2,5,7,12‐tetrahydroxy‐3,10‐dimethoxy‐2‐methyl‐3,4‐dihydrotetracene‐1,6,11‐trione) was isolated and had its structure confirmed by 1H nuclear magnetic resonance. The anthracyclines identified in this work show an interesting aminoglycoside, poorly found in natural products, 3‐methyl‐rhodosamine and derivatives. This fact encouraged to develop a focused method to identify compounds with aminoglycosides (rhodosamine, m/z 158; 3‐methyl‐rhodosamine, m/z 172; 4′‐O‐acethyl‐3‐C‐methyl‐rhodosamine, m/z 214). This method allowed the detection of four more anthracyclines. This focused method can also be applied in the search of these aminoglycosides in other microbial crude extracts. Additionally, it was observed that nocardicyclin A, nothramicin and compound 8 were able to interact to DNA through a DNA‐binding study by mass spectrometry, showing its potential as anticancer drugs. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
7.

Background  

Adjuvants are known to significantly enhance vaccine efficacy. However, commercial adjuvants often have limited use because of toxicity in humans. The objective of this study was to determine the comparative effectiveness of a diterpene alcohol, phyto l and its hydrogenated derivative PHIS-01, relative to incomplete Freund's adjuvant (IFA), a commonly used adjuvant in augmenting protective immunity in mice against E. coli and S. aureus, and in terms of inflammatory cytokines.  相似文献   
8.
9.
The splitting of water in the temperature range from 470 to 970 K was studied for a series of CoNaX zeolites of a Si/Al ratio of 1.18 and of different degree of exchange and at the parent type NaX. In case of CoNaX zeolites peaks at about 570 and 670 K and a broad flat peak at even higher temperatures could be observed. Both the first peaks are ascribed to the process of dehydroxylation between CoOH and structural OH groups, the latter to the dehydroxylation between structural OH groups only. The parent type provided only a single peak with a maximum at about 570 K.From the dehydroxylation peaks activation parameters have been calculated and a scheme has been suggested for the mechanism.
Zusammenfassung Im Temperaturbereich von 470–970 K wurde bei einer Reihe CoNaX Zeolithen mit einem Si/Al-VerhÄltnis von 1.18 und einem unterschiedlichen Austauschgrad sowie bei dem NaX Stammtyp die Abspaltung von Wasser untersucht. Im Falle von CoNaX Zeolithen können Peaks bei 570 und 670 K und ein breiter flacher Peak bei noch höheren Temperaturen beobachtet werden. Die beiden ersten Peaks werden dem Proze\ der Dehydroxylierung zwischen CoOH- und strukturellen OH-Gruppen, letzterer der Dehydroxylierung nur zwischen strukturellen OH-Gruppen zugeschrieben. Der Stammtyp ergibt nur einen einzigen Peak mit einem Maximum bei 570 K. Aus den Dehydroxylierungspeaks wurden Aktivierungsparameter berechnet und ein Mechanismusschema entwickelt.
  相似文献   
10.
Six O, O-diethyl-N-acylphosphoramidates ( 1a-f ) were synthesized. The reactions of their conjugate bases with haloalkanes were studied. The N/(phosphoryl)O/(carbonyl)O regioselectivity varied greatly, depending on the substrate, the haloalkane, the base, and other reaction conditions. The earlier [17] reaction of N-formyl substrate 1a that led to the N-phosphorylated formamidine was extended to other substrates 1 . Again, the yields and the selectivity depended strongly on the structure of a substrate.  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