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141.
The formamide acetals enter into two main categories of reactions, namely alkylation and formylation. As alkylating agents, they have been used in the synthesis of esters from acids, ethers and thioethers from phenols and aromatic and heterocyclic thiols, and the alkylation of active methines. As formylating agents, formamide acetals are useful in the synthesis of enamines from active methylenes and amidines from amines and amides. Also formamide acetals are efficient reagents for the conversion of α-hydroxycarboxylic acids to alkenes while trans-vic-diols yield epoxides. The above conversions as well as othere listed in the review proceed in almost all cases under mild conditions in high yields making these reagents valuable synthetic tools.  相似文献   
142.
    
Zusammenfassung Mit Hilfe statistischer Methoden wird die Anwendbarkeit der dilatometrischen Indikation bei der Wasserbestimmung nach Karl Fischer untersucht. Die Richtigkeit, Reproduzierbarkeit und Proportionalität sowie die Erfassungsgrenzen und die einfache Handhabung lassen diese Methode als ein für Forschung und Routine gleichermaßen einsetzbares Verfahren erscheinen. Der maximal erfaßbare Gehalt beträgt 300 mg H2O. Eine Bestimmung kann innerhalb von 10–15 min mit einer Standardabweichung von = 2,0 ausgeführt werden.Wir danken dem Fonds der chemischen Industrie für die finanzielle Unterstützung dieser Arbeit.  相似文献   
143.
Summary. A series of substituted pyridine, pyrazoline, and thiopyrimidine derivatives were synthesized from 3-acetylpyridine, which was prepared from nicotinic acid as a naturally starting material. The pharmacological screening showed that many of these compounds have good analgesic and antiparkinsonian activities comparable to Voltarene? and Benzatropine? as reference drugs. The structure assignment of the new compounds is based on chemical and spectroscopic evidence. The detailed synthesis, spectroscopic data, and pharmacological properties for synthesized compounds are reported.  相似文献   
144.
Signature-based techniques are well known for the Built-in Self-test of integrated systems. We propose a novel test architecture which uses a judicious combination of mutual testing and signature testing to achieve low test area overhead, low aliasing probability and low test application time. The proposed architecture is powerful for testing highly concurrent systems in applications such as iterative logic arrays, real-time systems, systolic arrays, and low-latency pipelines which tend to have a large number of functional modules of a similar nature. The use of mutual testing helps in testing self-loop modules which cannot be tested using simple signature-based schemes. We provide graph-theoretic optimization algorithms to optimize the test area and test application time of the resulting test architecture.  相似文献   
145.
This study shows the effects of the Tween 60 emulsifier at different concentrations on the aqueous emulsion containing 5% of Pistacia lentiscus fruit oil. The rheological behavior and the droplet size distribution of cosmetic oil-in-water emulsions were investigated. This investigation was carried out by analyzing the shear flow and dynamic oscillatory followed by microscopic analysis and physical stability study for 24?hours and 4 months. During the period of 4 months, the emulsions were stored in a refrigerator at a semi-low temperature 12?°C. The physical stability test showed that the sample not emulsified yielded a creaming process after a short aging time. Flow curves of emulsions prepared with TW 60 exhibited a non-linear relationship between the shear stress σ and shear rate γ ?, which implies that the Herschel–Bulkley rheological model was the appropriate model for the shear flow. The increase of emulsifier quantities leading to an increase in the internal structure coherence, whereas the excess quantity affects the structure. Therefore, the optimal quantity proposed was 3.47%. Furthermore, the storage time at a semi-low temperature performed the stability and maintain the structure of emulsions.  相似文献   
146.
本文中我们采用标志重捕方法从2003到2004年11月,对栖息在野花带的普通田鼠种群结构和数量动态进行比较系统的研究.结果表明,这两年中种群密度夏季最大分别达到410个体/ha和641个体/ha,春季最少分别达到166个体/ha和153个体/ha,从7月份开始增长,8月份种群密度减少并在11月份开始重新增长.种群中雌性个体数量比较多,雌性在种群中的居留时间比较长同时存活率比雄性高,这种现象导致种群数量的季节变化.种群周转率比较高,在两个捕鼠期间种群中的80%个体被更新,这表明普通田鼠在野花带中的活动非常活跃,不断与周围的其它种群进行交流,提高种群对环境的适应能力.种群中雌雄个体的领域之间没有年间变化,它们的活动领域比较小,领域长度2003年平均为11米,最长为37.5米,2004年平均为13米,最长为52米.本研究中我们没有找到环境因素和种群数量动态之间的相关关系.  相似文献   
147.
Radon alpha activity concentration has been measured in 28 homes in the Erbil Capital-Iraqi Kurdistan region during the autumn season by using time-integrated passive radon dosimeters containing CR-39 solid state nuclear track detectors “SSNTDs”. The radon activity concentrations in these homes range from (10.33–90.34) with an average of . The average absorption effective dose equivalent for a person living in homes for which the investigation were done was found to be , obtained by using an equilibrium factor of 0.5 and an occupancy factor of 0.8. The average lung cancer cases per year per 106 person was found to be 23±12.  相似文献   
148.
A green cellular technology is proposed to optimize the energy and spectrum resources. Such optimization will require perfect channel state information at the transmitting base station. However, reporting the channel status of the entire bandwidth requires huge undesirable feedback overhead. Therefore, the aim of this paper is to optimize the energy and bandwidth resources while maintaining quality-of-service at the downlink when a partial feedback is considered. In this paper, a modified downlink scheduler based on a Packet Prediction Mechanism (PPM) is conducted at the eNodeB to optimize the energy and spectrum resources. On the user equipment side, a partial channel feedback scheme based on an adaptive feedback threshold is developed. A primary concern of this feedback scheme is to reduce the uplink signaling overhead without a substantial loss in downlink performances. Finally, the downlink packet scheduling and the partial feedback are jointly evaluated to further enhance the system performance. Based on a system-level simulation results, the proposed energy-efficient scheduling with partial feedback has achieved an improvement in EE of up to 79% compared to the PPM scheduler. Besides, it minimizes the degradation caused by the partial channel quality indicator feedback. Thus, the proposed two-sided algorithm gives the best tradeoff between uplink and downlink performances.  相似文献   
149.
Cancer is one of the most serious issues in human life. Blocking programmed cell death protein 1 and programmed death ligand-1 (PD-L1) pathway is one of the great innovations in the last few years, a few numbers of inhibitors can be able to block it. (2-Methyl-3-biphenylyl) methanol derivative is one of them. Here, the quantitative structure-activity relationship (QSAR) established twenty (2-methyl-3-biphenylyl) methanol derivatives as the programmed death ligand-1 inhibitors. Density functional theory at the B3LPY/6-31+G(d, p) level was employed to study the chemical structure and properties of the chosen compounds. Highest occupied molecular orbital energy \begin{document}$E_{\rm{HOMO}}$\end{document}, lowest unoccupied molecular orbital energy \begin{document}$E_{\rm{LUMO}}$\end{document}, total energy \begin{document}$E_{\rm{T}}$\end{document}, dipole moment DM, absolute hardness \begin{document}$\eta$\end{document}, absolute electronegativity \begin{document}$\chi$\end{document}, softness \begin{document}$S$\end{document}, electrophilicity \begin{document}$\omega$\end{document}, energy gap \begin{document}$\Delta E$\end{document}, etc., were observed and determined. Principal component analysis (PCA), multiple linear regression (MLR) and multiple non-linear regression (MNLR) analysis were carried out to establish the QSAR. The proposed quantitative models and interpreted outcomes of the compounds were based on statistical analysis. Statistical results of MLR and MNLR exhibited the coefficient \begin{document}$R^2$\end{document} was 0.661 and 0.758, respectively. Leave-one-out cross-validation, \begin{document}$r^2_{\rm{m}}$\end{document} metric, \begin{document}$r^2_{\rm{m}}$\end{document} test, and "Golbraikh &; Tropsha's criteria" analyses were applied for the validation of MLR and MNLR, which indicate two models are statistically significant and well stable with data variation in the external validation towards PD-L1. The obtained results showed that the MNLR model predicts the bioactivity more accurately than MLR, and it may be helpful and supporting for evaluation of the biological activity of PD-L1 inhibitors.  相似文献   
150.
Magnetic insulators can be characterized by a gap separating the singlet ground state from the lowest-energy triplet, S=1 excitation. If the gap can be closed by the Zeeman interaction in applied magnetic field, the resulting quasiparticles, triplons, can have concentrations sufficient to undergo the Bose–Einstein condensates transition. We consider macroscopic properties of the triplon Bose–Einstein condensates in the Hartree–Fock–Bogoliubov approximation taking into account the anomalous averages. We prove that these averages play the qualitative role in the condensate properties. As a result, we show that with the increase in the external magnetic field at a given temperature, the condensate demonstrates an instability related to the appearance of nonzero phonon damping and a change in the characteristic dependence of the speed of sound on the magnetic field. The calculated magnetic susceptibility diverges when the external magnetic field approaches this instability threshold, providing a tool for the experimental verification of this approach.  相似文献   
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