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91.
Cristina Paradisi Hilkka Kenttmaa Quang T. Le Marjorie C. Caserio 《Journal of mass spectrometry : JMS》1988,23(7):521-526
A Fourier transform–ion cyclotron resonance study of thioacyl compounds as binary mixtures with unsaturated hydrocarbons has revealed that thioacetylium ions CH3CS+ generated by electron fragmentation fail to thioacyl-ate even the most reactive aromatic hydrocarbons. Among the hydrocarbons studied, only 3-hexyne and 2,4-dimethyl-2,5-hexadiene were observed to react with CH3CS+. Apart from proton-transfer reactions, the major ionic reaction of thioesters with arenes, alkynes and alkenes is condensation of the molecular ion of one component, usually the ester, with a neutral molecule of the other, resulting in the cleavage of the S? Calkyl bond of the thioester. The nature of this reaction is discussed and a possible mechanism is suggested. 相似文献
92.
Quang Shen 《Journal of Molecular Structure》1981,75(2):303-310
The molecular structure and conformation of cis-1,3-dichloro-1-propene have been determined by gas phase electron diffraction at a nozzle temperature of 90°C. The molecule exists in a form in which the chlorine atom of the methyl group and the carbon-carbon double bond are gauche to one another. The results for the distance (rg) and angle (∠α) parameters are: r(C-H) = 1.078(10)Å, r(CC) = 1.340(5)Å, r(C-C) = 1.508(7)Å, r( =C-Cl) = 1.762(3)Å, r(C-Cl) = 1.806(3)Å, ∠Cl-C-C = 111.7°(1.8), ∠(CC-C) = 125.5°(1.5), ∠Cl-CC = 124.6°(1.6) and ∠H-C-Cl = 111°(5). The torsion-sensitive distances close to the gauche form can be approximated using a dynamic model with a quartic double minimum potential function of the form V(Φ) = V0[1 + (4 - 2()2], where Vo = 1.1(8) kcal mol?1 and Φ0 = 56°(5) (Φ = 0 corresponds to the anti form). 相似文献
93.
Keller Fcred A. Bates Delicia Ruiz Ray Nguyen Quang 《Applied biochemistry and biotechnology》1998,(1):137-148
Several strains and genera of yeast, includingSaccharomyces cerevisiae D5A,Pachysolen tannophilus, S. cerevisiae K-l,Brettanomyces custersii, Candida shehatae, andCandida acidothermophilum, are screened for growth on dilute acid-pretreated softwood prehydrolysate. Selected softwood species found in forest underbrush
of the western United States, which contain predominantly hexosan hemicellulose, were studied. This phase of the work emphasized
debarked Douglas fir. The two best initial isolates were gradually selected for improved growth by adaptation to increasing
prehydrolysate concentrations in batch culture, with due consideration of nutrient requirements. Microaerophilic conditions
were evaluated to encourage tolerance of pretreatment hydrolysate, as well as ethanol product. Adaptation and simultaneous
saccharification and fermentation (SSF) results are used to illustrate improved performance with an adapted strain, compared
to the wild type. 相似文献
94.
Fred A. Keller Jenny E. Hamilton Quang A. Nguyen 《Applied biochemistry and biotechnology》2003,105(1-3):27-41
Typical pretreatment requires high-energy (steam and electricity) and corrosion-resistant, high-pressure reactors. A review
of the literature suggests that fungal pretreatment could potentially lower the severity requirements of acid, temperature
and time. These reductions in severity are also expected to result in less biomass degradation and consequently lower inhibitor
concentrations compared to conventional thermochemical pretreatment. Furthermore, potential advantages of fungal pretreatment
of agricultural residues, such as corn stover, are suggested by its effectiveness in improving the cellulose digestibility
of many types of forage fiber and agricultural wastes. Our preliminary tests show a three- to five-fold improvement in enzymatic
cellulose digestibility of corn stover after pretreatment with Cyathus stercoreus; and a ten- to 100-fold reduction in shear force needed to obtain the same shear rate of 3.2 to 7 rev/s, respectively, after
pretreatment with Phanerochaete chrysosporium. 相似文献
95.
Nguyen-Trung NQ Botta O Terenzi S Strazewski P 《The Journal of organic chemistry》2003,68(5):2038-2041
3'-aminoacylamino-3'-deoxyadenosines, analogues of the antibiotic puromycin, have been synthesized from adenosine. They key 3'-azido derivative 10 was obtained through a 3'-oxidation/reduction/substitution procedure. A modified purification protocol on a larger scale was developed for the oxidation step using the Garegg reagent. The coupling reaction between an Fmoc-l-amino acid and the fully protected form of 3'-amino-3'-deoxyadenosine 11 furnished the aminoacylated compounds 12 in high yields. The puromycin analogues were obtained in 10 steps and up to 23% (14c) overall yield. 相似文献
96.
Phan Van Kiem Chau Van Minh Nguyen Xuan Nhiem Nguyen Thi Cuc Ngo Van Quang Hoang Le Tuan Anh Bui Huu Tai Pham Hai Yen Nguyen Thi Hoai Kim Young Ho Nanyoung Kim SeonJu Park Seung Hyun Kim 《Magnetic resonance in chemistry : MRC》2014,52(1-2):51-56
Seven new muurolane‐type sesquiterpenes, (4R,5R)‐muurol‐1(6),10(14)‐diene‐4,5‐diol (1), (4R,5R)‐muurol‐1(6)‐ene‐4,5‐diol (2), (4R,5R,10R)‐10‐methoxymuurol‐1(6)‐ene‐4,5‐diol (3), (4S)‐4‐hydroxy‐1,10‐seco‐muurol‐5‐ene‐1,10‐dione (4), (4R)‐4‐hydroxy‐1,10‐seco‐muurol‐5‐ene‐1,10‐dione (5), (6S,10S)‐6,10‐dihydroxy‐7,8‐seco‐2,8‐cyclo‐muurol‐4(5),7(11)‐diene‐12‐oic acid (6), and (6R,10S)‐6,10‐dihydroxy‐7,8‐seco‐2,8‐cyclo‐muurol‐4(5),7(11)‐diene‐12‐oic acid (7) were isolated from the marine sponge Dysidea cinerea. Their structures were determined by the combination of spectroscopic and chemical methods, including 1D‐NMR, 2D‐NMR, and CD spectra as well as by comparing the NMR data with those reported in the literature. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
97.
98.
99.
Wu Du Quang Truong Hongbo Qi Yan Guo Harry R. Chobanian William K. Hagmann Jeffrey J. Hale 《Tetrahedron letters》2007,48(13):2231-2235
Herein we report a high yielding one-pot ‘green’ synthesis of 3-substituted-5-carbonylmethyl-1,2,4-oxadiazoles from readily available β-keto esters and amidoximes under simple and convenient solvent-free conditions. No additional base is needed. The reaction likely goes through an acyl ketene intermediate. 相似文献
100.
Nguyen Dinh Phu Le Thanh Quang Tran Thanh Tung 《Nonlinear Analysis: Theory, Methods & Applications》2008
The existence and comparison results on solutions of set control differential equation were studied in [N.D. Phu, T.T. Tung, Some results on sheaf-solutions of sheaf set control problems, Nonlinear Analysis 67 (2007) 1309–1315]. In this paper, we present the stability criteria for solutions of set control differential equation. 相似文献