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981.
Rhodium‐Catalyzed Oxidative Benzannulation of N‐Pivaloylanilines with Internal Alkynes through Dual C−H Bond Activation: Synthesis of Highly Substituted Naphthalenes 下载免费PDF全文
Dr. Xuan Zhang Dr. Xiaoqiang Yu Dr. Xiujuan Feng Prof. Dr. Yoshinori Yamamoto Dr. Abdulrahman I. Almansour Dr. Natarajan Arumugam Dr. Raju Suresh Kumar Prof. Dr. Ming Bao 《化学:亚洲杂志》2016,11(22):3241-3250
An efficient method was developed for the synthesis of highly substituted naphthalenes through rhodium‐catalyzed oxidative benzannulation of N‐pivaloylanilines with internal alkynes. The benzannulation reaction proceeded smoothly through dual C?H bond activation to produce the corresponding highly substituted naphthalene products in satisfactory to good yields. 相似文献
982.
Che-Jung Chang Liping Yu Peng Jin 《The Journal of the Operational Research Society》2016,67(12):1439-1445
Accurate short-term demand forecasting is critical for developing effective production plans; however, a short forecasting period indicates that the product demands are unstable, rendering tracking of product development trends difficult. Determining the actual developing data patterns by using forecasting models generated using historical observations is difficult, and the forecasting performance of such models is unfavourable, whereas using the latest limited data for forecasting can improve management efficiency and maintain the competitive advantages of an enterprise. To solve forecasting problems related to a small data set, this study applied an adaptive grey model for forecasting short-term manufacturing demand. Experiments involving the monthly demand data for thin film transistor liquid crystal display panels and wafer-level chip-scale packaging process data showed that the proposed grey model produced favourable forecasting results, indicating its appropriateness as a short-term forecasting tool for small data sets. 相似文献
983.
In this paper, we focus on stochastic reaction-diffusion equations with jumps. By a new auxiliary function, we investigate non-negative property of the local strong (variational) solutions, which applies to stochastic reaction-diffusion equations with highly nonlinear noise terms. As a byproduct, we study the problem of non-existence of global strong solutions by imposing appropriate conditions on the drift terms, which can cover many more models than the existing literature. Moreover, we also investigate the subject of Lévy-type noise-induced explosion by bringing some plausible assumptions to bear on the noise terms, which, however, need not guarantee local strong (variational) solutions to enjoy the non-negative property. Meanwhile, several examples are presented to illustrate the theory established. 相似文献
984.
通过溶胶-凝胶法合成了一系列Mn掺杂K-Co-Mo催化剂,并利用X射线衍射、N2吸脱附、NH3程序升温脱附、原位漫反射红外光谱以及X射线吸收谱等技术对催化剂的结构进行了表征.活性测试结果显示Mn掺杂催化剂比未掺杂催化剂表现更高的合成低碳醇的催化活性,尤其是C2+醇的选择性得到了明显的提高.醇产物分布偏离了ASF分布规律,甲醇的含量显著减少,乙醇成为主要醇产物.表征结果表明Mn助剂的加入增强了Co和Mo之间的相互作用,促进了醇生成活性中心Co-Mo-O物种的生成.显著减少了催化剂强酸性位的数量,促进了弱酸性位的产生,有利于醇产物的生成.助剂的加入有利于催化剂对CO的线性和桥式吸附,促进了醇产物的生成和碳链的增长,提高了催化剂对C2+醇的选择性. 相似文献
985.
对机器人体系结构、动作学习及行为的组织方式进行了研究,以演化计算为基本方法,以RoboCup2D为平台,设计了基于PSO算法的足球机器人的体系结构,解决感知、动作、和规划问题;在训练环境下,形成感知规则,优化感知相关参数,得到对信息高效快速的感知方法,并根据指定的粒度、功能、参数,对RoboCup2D机器人的原子动作进行了组合优化,得到一组带参数和执行效果描述的粒子动作;最后在赛场环境和任务驱动下,搜索粒子动作并进行组织规划,得到完成特定任务的机器人行为;RoboCup2D仿真实验表明,演化计算方法不仅能利用原子动作进行组合优化,得到适应于不同条件的粒子动作,而且能通过其在线搜索粒子动作,动态组成机器人行为;基于演化计算的足球机器人能更好地完成跑位、截球、带球、传球等任务,具有更强的适应性。 相似文献
986.
针对北斗B1频率的I支路信号,设计并实现了北斗软件接收机的基带处理部分。阐述了北斗B1频点信号的扩频体制和产生过程,并行码相位搜索捕获策略以及鉴相辅助跟踪环路,并设计了二阶数字环路滤波器,滤波器参数取ζ=0.707,B_n=25(Hz)。同时采用Matlab软件,仿真北斗中频数字信号,编码实现捕获跟踪算法,并分别通过对仿真信号和真实卫星信号的捕获跟踪,验证捕获跟踪算法的可行性,并提出锁频环辅助锁相环算法的改进思路。为进一步开展北斗软件接收机相关技术研究打下了基础。 相似文献
987.
Twenty chiral pesticides were tested, of which seven samples were directly separated by HPLC using cellulose tris-3,5-dimethyl carbamate (CDMPC) chiral stationary phase under RP conditions. The influence of mobile phase composition and column temperatures from 0 degrees C to 40 degrees C on the separations were investigated. The mobile phases were methanol/water or ACN/water at a flow rate of 0.8 mL/min with UV detection at 230 or 210 nm. Epoxiconazole, terallethrin, benalaxyl, and diclofopmethyl were observed to obtain the baseline separation under suitable conditions and other pesticides pyriproxyfen, lactofen, and quizalofop-ethyl were separated partially. The retention factors (k) and selectivity factor (alpha) for the enantiomers of most investigated pesticides decreased upon increasing the temperature except for the selectivity factors (alpha) of pyriproxyfen in methanol/water. The ln alpha - 1/T plots for racemic chiral pesticides were linear at the range of 0-40 except for that of pyriproxyfen enantiomers in methanol/water and the chiral separations were controlled by enthalpy. Better separations were not always at low temperature. The elution orders of the eluting enantiomers were determined by a circular dichroism (CD) detector. 相似文献
988.
Antibacterial thymol derivatives isolated from Centipeda minima 总被引:1,自引:0,他引:1
Liang H Bao F Dong X Tan R Zhang C Lu Q Cheng Y 《Molecules (Basel, Switzerland)》2007,12(8):1606-1613
Two new monoterpenoids, 8,10-dihydroxy-9(2)-methylbutyryloxythymol (1) and 10-hydroxy-8,9-dioxyisopropylidene-thymol (2), together with five known thymol derivatives: 8,9,10-trihydroxythymol (3), thymol-beta-glucopyranoside (4), 9-hydroxythymol (5), 8,10-dihydroxy-9-isobutyryloxythymol (6), and 8-hydroxy-9,10-diisobutyryloxythymol (7), were isolated from Centipeda minima. Their structures were identified by means of spectroscopic analyses. Interestingly, compound 2 is not an extraction artifact according to a close HPLC examination of material after extraction by analytical MeOH at ambient temperature. The antibacterial activities of compounds 1-7 were evaluated against eight microbial strains by the agar dilution method. 相似文献
989.
The parent pyrrolidino[2',3':3,4]pyrrolidino[1,2-a]benzimidazole heterocycle as well as a series of novel analogues have been synthesized utilizing a microwave-assisted intramolecular cycloaddition of azomethine ylides as the key transformation. A variety of diversity groups were added to explore the scope of this reaction and to provide a number of new compounds for biological screening. 相似文献
990.
Lu W Du L Wang M Jia X Wen J Huang Y Guo Y Gong W Bao H Yang J Sun B 《Applied biochemistry and biotechnology》2007,142(1):17-28
A new method for breeding the hydrocortisone overproducing strain Curvularia lunata by screening ketoconazole-resistance mutant was developed. A hydrocortisone overproducing mutant C. lunata KA-91 with ketoconazole-resistance marker was obtained from protoplasts treated with ultraviolet radiation. The hydrocortisone
conversion rate of C. lunata KA-91 was increased by 42.1% compared to the original strain CL-114 at the substrate 17α-hydroxypregn-4-en-3, 20-dione-21-acetate
addition concentration of 1.0 g/L. The by-products produced by KA-91 were fewer than those of the original strain. It was
assumed that the higher cytochrome P450 content of ketoconazole-resistance mutant resulted in the increase of 11β-hydroxylation
capacity. The culture conditions for biotransformation of 17α-hydroxypregn-4-en-3, 20-dione-21-acetate to hydrocortisone were
optimized by response surface methodology. Plackett–Burman design was applied to elucidate the key factors affecting the hydrocortisone
production, and the results indicated that glucose, initial pH, and glucose to total nitrogen sources ratio (ω) had significant effects on hydrocortisone production. Box–Behnken design was employed to search for the optimal parameters
of those three key factors. According to the model, the trial checking at the optimal conditions showed a high hydrocortisone
conversion rate of 82.67%. 相似文献