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991.
992.
Dr. Sui‐Jun Liu Chen‐Chao Xie Ji‐Min Jia Jiong‐Peng Zhao Song‐De Han Yu Cui Yue Li Prof. Dr. Xian‐He Bu 《化学:亚洲杂志》2014,9(4):1116-1122
Four carboxylate‐bridged GdIII complexes ( 1 – 4 ) with 1D/2D structures have been synthesized by using the hydrothermal reaction of Gd2O3 with various carboxylate ligands. Compounds 1 and 2 contained the same [2n] GdIII? OH ladders, but with different crystallographically independent GdIII ions, whilst the structures of compounds 3 and 4 were composed of [Gd4(μ3‐OH)2(piv)8(H2O)2]2+ units and 1D ladder GdIII chains, respectively. Antiferromagnetic interactions occurred in compounds 1 – 3 , owing to their small Gd? O? Gd angles, whereas ferromagnetic coupling occurred in compound 4 , in which the Gd? O? Gd angles were larger. These complexes exhibited a distinct magnetocaloric effect (MCE), which was affected by their different magnetic densities and exchange interactions. Among these compounds, complex 4 presented the largest MCE (?ΔSmmax=43.6 J kg?1 K?1), the lowest Mw/NGd ratio (the highest magnetic density), and weak ferromagnetic coupling. Therefore, a lower Mw/NGd ratio and weaker exchange interactions (a smaller absolute value of θ) between GdIII ions resulted in a larger MCE for the GdIII complexes. 相似文献
993.
Sonocrystallization Yields Monoclinic Paracetamol with Significantly Improved Compaction Behavior 下载免费PDF全文
Dr. Dejan‐Krešimir Bučar Dr. James A. Elliott Dr. Mark D. Eddleston Dr. Jeremy K. Cockcroft Prof. William Jones 《Angewandte Chemie (International ed. in English)》2015,54(1):249-253
Ultrasound‐assisted crystallization (sonocrystallization) was used to prepare a mixture of nano‐ and micrometer‐sized crystals of the monoclinic form of paracetamol—a widely used analgesic known for its particularly problematic mechanical behavior under compression (i.e. poor tabletability). The nano‐ and micrometer‐sized crystals yielded a powder which exhibits elastic moduli and bulk cohesions that are significantly higher than those observed in samples consisting of macrometer‐sized crystals, thus leading to enhanced tabletability without the use of excipients, particle coating, salt, or cocrystal formation. Experimental compaction and finite element analysis were utilized to rationalize the significantly improved compaction behavior of the monoclinic form of paracetamol. 相似文献
994.
Imidazolin‐2‐ylidenaminophosphines as Highly Electron‐Rich Ligands for Transition‐Metal Catalysts 下载免费PDF全文
Marius A. Wünsche Paul Mehlmann Tim Witteler Florenz Buß Patrick Rathmann Dr. Fabian Dielmann 《Angewandte Chemie (International ed. in English)》2015,54(40):11857-11860
A variety of chemical transformations benefit from the use of strong electron‐donating ancillary ligands, such as alkylphosphines or N‐heterocyclic carbenes when electron‐rich metal centers are required. Herein, we describe a facile and highly modular access to monodentate and bidentate imidazolin‐2‐ylidenamino‐substituted phosphines. Evaluation of the phosphine’s electronic properties substantiate that the formal replacement of alkyl or aryl groups by imidazolin‐2‐ylidenamino groups dramatically enhance their donor ability beyond that of alkylphosphines and even N‐heterocyclic carbenes. The new phosphines have been coordinated onto palladium(II) centers, and the beneficial effect of the novel substitution patterns has been explored by using the corresponding complexes in the palladium‐catalyzed Suzuki–Miyaura cross‐coupling reaction of non‐activated aryl chloride substrates. 相似文献
995.
Wenpei Fan Wenbo Bu Zhen Zhang Bo Shen Hui Zhang Qianjun He Dalong Ni Zhaowen Cui Kuaile Zhao Jiwen Bu Jiulin Du Jianan Liu Jianlin Shi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(47):14232-14236
Multifunctional stimuli‐responsive nanotheranostic systems are highly desirable for realizing simultaneous biomedical imaging and on‐demand therapy with minimized adverse effects. Herein, we present the construction of an intelligent X‐ray‐controlled NO‐releasing upconversion nanotheranostic system (termed as PEG‐USMSs‐SNO) by engineering UCNPs with S‐nitrosothiol (R‐SNO)‐grafted mesoporous silica. The PEG‐USMSs‐SNO is designed to respond sensitively to X‐ray radiation for breaking down the S N bond of SNO to release NO, which leads to X‐ray dose‐controlled NO release for on‐demand hypoxic radiosensitization besides upconversion luminescent imaging through UCNPs in vitro and in vivo. Thanks to the high live‐body permeability of X‐ray, our developed PEG‐USMSs‐SNO may provide a new technique for achieving depth‐independent controlled NO release and positioned radiotherapy enhancement against deep‐seated solid tumors. 相似文献
996.
997.
T. Dostalová H. Jelinková J. ?ulc M. Němec M. Fibrich M. Jelínek P. Michalík M. Bu?ková 《Laser Physics》2012,22(9):1395-1400
Ceramic brackets often used for an orthodontic treatment can lead to problems such as enamel tear outs because of their low fracture resistance and high bond strengths. Therefore the aim of our study was to investigate the positive laser radiation effect on bracket debonding. Moreover, the influence of the enamel shape surface under the bracket and laser radiation power on the debonding strength was investigated. The source of the radiation was the longitudinally diode-pumped Tm:YAP laser operating at 1997 nm. To eliminate the tooth surface roughness the flat enamel surface was prepared artificially and the bracket was bonded on it. The debonding was accomplished by Tm:YAP laser radiation with different the power value while recording the temperature rise in the pulp. To simulate the debonding process in vivo the actual bond strength was measured by the digital force gauge. The results were analyzed by scanning electron microscope. 相似文献
998.
Shao‐Min Wang Shan‐Shan Bu Hong‐Min Liu Hua‐Yu Li Wei Liu Yu‐Dong Wang 《Rapid communications in mass spectrometry : RCM》2009,23(6):899-906
A simple high‐performance liquid chromatography/electrospray ionization tandem mass spectrometric (HPLC/ESI‐MS/MS) method has been developed for the rapid identification of clindamycin phosphate and its degradation products or related impurities in clindamycin phosphate injection. Detection was performed by quadrupole time‐of‐flight mass spectrometry (Q‐TOFMS) via an ESI source in positive mode. Clindamycin phosphate and its related substances lincomycin, 7‐epilincomycin‐2‐phosphate, lincomycin‐2‐phosphate, clindamycin B, clindamycin B‐2‐phosphate, and clindamycin were identified simultaneously by HPLC/ESI‐MS/MS results. Based on the MS/MS spectra of their quasi‐molecular ions, the fragmentation pathways of clindamycin phosphate and its related substances were compared and proposed, which are specific and useful for the identification of the lincosamide antibiotics and related impurities. The method was rapid, sensitive and specific and can be used to identify clindamycin phosphate and its related impurities in clindamycin phosphate injection without control compounds. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
999.
从激光晶体低增益谱线的运转机理出发,对LD泵浦NdYAG,LBO腔内倍频556 nm激光器所使用的光学薄膜进行了研制.在激光反射镜的设计上,为保证基频光1 112 nm的高效振荡,并获得高的倍频556 nm激光输出,对膜系要求进行了深入分析.采用离子束反应溅射和离子辅助沉积的方法,运用时间监控膜厚法成功置备出556 nm激光器所使用的特殊的全介质激光反射膜,在国内首次实现了1 112 nm激光高效振荡,通过LBO腔内倍频,在2 W的LD泵浦功率下获得102 mW 556 nm激光输出. 相似文献
1000.
Zhi Min LIU GuanYing YANG Dan LI Bu Xing HAN* Center for Molecular Science Institute of Chemistry Chinese Academy of Sciences Beijing 《中国化学快报》2001,(2)
Supercritical (SC) CO2 can plasticize many amorphous polymers, which reduce the glass transition temperature of the polymers significantly. Recently, it was used as blowing agent to foam amorphous materials such as poly(methyl methacrylate) (PMMA)1,2, polystyrene (PS)3, polycarbonate (PC)4 and poly(ethylene terephthalate) (PET)4. In this foaming process, a polymer is saturated with SC CO2, and followed by rapid depressurization to atmospheric pressure. The microcellular foams can be ob… 相似文献