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Hexamethyl 13,14-dioxapentacyclo[,7.02,9.03,8]tetradeca-5,11-diene-1,4,5,6,11,12-hexacarboxylate
Alan J. Lough,Kelsey Jack,William Tam
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812039232
Abstract: In the title compound, C24H24O14, the stereochemistry at the cyclobutane ring is cis-anti-cis and the –COOMe groups in the bicyclic rings are syn to each other. The molecule lies on a twofold rotation axis. In the crystal, weak C—H...O hydrogen bonds connect molecules into chains along [001], forming R22(10) rings.
Tetramethyl 1,4-dimethyl-13,14-dioxapentacyclo[,7.02,9.03,8]tetradeca-5,11-diene-5,6,11,12-tetracarboxylate  [cached]
Alan J. Lough,Kelsey Jack,William Tam
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812039219
Abstract: In the title compound, C22H24O14, the relative stereochemistry at the cyclobutane ring is cis-anti-cis and the methyl groups in the bicyclic rings are syn to each other. The two carboxylate groups attached to the same —C=C— bond are disordered over two sets of sites in a 0.603 (2):0.397 (2) ratio. In the crystal, weak C—H...O hydrogen bonds connect molecules into C(12) chains along [001] incorporating R222(10) rings.
Pentacyclo[,7.02,9.03,8]tetradeca-5,11-diene  [cached]
Hsing-Yang Tsai,Ming-Hui Luo,Wei-Chi Lin,Che-Wei Chang
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812038780
Abstract: The title compound, C14H16, was prepared through [2 + 2] cycloaddition of norbornadiene. There are two independent molecules in the asymmetric unit: each is centrosymmetric with the centroid of the four-membered ring located about an inversion center. Each molecule possesses an exo–trans–exo conformation.
Mg-7Zn-xY-0.6Zr(x=5,11)合金的腐蚀行为研究  [PDF]
哈尔滨工程大学学报 , 2017, DOI: 10.11990/jheu.201601098
Abstract: 为了探讨Mg-7Zn-xY-0.6Zr(x=5,11)合金在自然界的耐腐蚀性能,采用失重法和电化学法对两种合金在3.5% NaCl溶液中的腐蚀行为和电化学行为进行研究。结果表明,含5% Y合金的腐蚀速率较快,这是由二者不同的第二相种类和分布所造成的。含5% Y合金中的非连续网状W相不能有效阻隔腐蚀液侵入合金内部,而含11% Y合金中的与腐蚀表面法线方向成大角度分布的连续层片状X相可以有效减缓合金内部受到进一步腐蚀。两种合金的腐蚀产物均为Mg(OH)2和Y2O3,但含11% Y合金的腐蚀产物在腐蚀表面覆盖的致密程度和均匀程度较高。含5% Y和含11% Y两种合金的腐蚀电位分别为-1.624 4 V和-1.597 8 V。
First Identification of 5,11-Dideoxytetrodotoxin in Marine Animals, and Characterization of Major Fragment Ions of Tetrodotoxin and Its Analogs by High Resolution ESI-MS/MS  [PDF]
Mari Yotsu-Yamashita,Yuka Abe,Yuta Kudo,Raphael Ritson-Williams,Valerie J. Paul,Keiichi Konoki,Yuko Cho,Masaatsu Adachi,Takuya Imazu,Toshio Nishikawa,Minoru Isobe
Marine Drugs , 2013, DOI: 10.3390/md11082799
Abstract: Even though tetrodotoxin (TTX) is a widespread toxin in marine and terrestrial organisms, very little is known about the biosynthetic pathway used to produce it. By describing chemical structures of natural analogs of TTX, we can start to identify some of the precursors that might be important for TTX biosynthesis. In the present study, an analog of TTX, 5,11-dideoxyTTX, was identified for the first time in natural sources, the ovary of the pufferfish and the pharynx of a flatworm (planocerid sp. 1), by comparison with totally synthesized (?)-5,11-dideoxyTTX, using high resolution ESI-LC-MS. Based on the presence of 5,11-dideoxyTTX together with a series of known deoxy analogs, 5,6, 11-trideoxyTTX, 6,11-dideoxyTTX, 11-deoxyTTX, and 5-deoxyTTX, in these animals, we predicted two routes of stepwise oxidation pathways in the late stages of biosynthesis of TTX. Furthermore, high resolution masses of the major fragment ions of TTX, 6,11-dideoxyTTX, and 5,6,11-trideoxyTTX were also measured, and their molecular formulas and structures were predicted to compare them with each other. Although both TTX and 5,6,11-trideoxyTTX give major fragment ions that are very close, m/z 162.0660 and 162.1020, respectively, they are distinguishable and predicted to be different molecular formulas. These data will be useful for identification of TTXs using high resolution LC-MS/MS.
Rubrene endoperoxide acetone monosolvate
Kiyoaki Shinashi,Akira Uchida
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812008835
Abstract: The title acetone solvate, C42H28O2·C3H6O [systematic name: 1,3,10,12-tetraphenyl-19,20-dioxapentacyclo[,11.04,9.013,18]icosa-2(11),3,5,7,9,13,15,17-octaene acetone monosolvate], is a photooxygenation product of rubrene (systematic name: 5,6,11,12-tetraphenyltetracene). The molecule bends at the bridgehead atoms, which are linked by the O—O transannular bond, with a dihedral angle of 49.21 (6)° between the benzene ring and the naphthalene ring system of the tetracene unit. In the crystal, the rubrene molecules are linked by C—H...O hydrogen bonds into a column along the c axis. The acetone solvent molecules form a dimer around a crystallographic inversion centre through a carbonyl–carbonyl dipolar interaction. A C—H...O hydrogen bond between the rubrene and acetone molecules is also observed.
Spectroscopy of 13,14B via the one-neutron knockout reaction  [PDF]
V. Guimaraes,J. J. Kolata,D. Bazin,B. Blank,B. A. Brown,T. Glasmacher,P. G. Hansen,R. W. Ibbotson,D. Karnes,V. Maddalena,A. Navin,B. Pritychenko,B. M. Sherrill
Physics , 2000, DOI: 10.1103/PhysRevC.61.064609
Abstract: The single-nucleon knockout reactions 9Be(14B, 13B + gamma)X and 197Au(14B, 13B + gamma)X, at an incident energy of 60 MeV per nucleon, have been used to probe the structure of 14B and of the core fragment 13B. A dominant 2s configuration is deduced for the neutron in the ground state of 14B. The longitudinal momentum distribution for this state is consistent with "neutron halo" structure. Spin assignments for 13B excited states at 3.48 and 3.68 MeV are proposed based on the observed spectroscopic factors for one-neutron removal.
Newlower bounds of classical Ramsey numbersR(4 ,12) ,R(5,11)andR(5,12)

Wenlong Su,Haipeng Luo,Qiao Li,

科学通报(英文版) , 1998,
5,11-Dimethyl-6,12-dimethoxyindolo[3,2-b]carbazole  [cached]
Norma Wrobel,Bernhard Witulski,Dieter Schollmeyer,Heiner Detert
Acta Crystallographica Section E , 2013, DOI: 10.1107/s1600536813001463
Abstract: The title compound, C22H20N2O2, was prepared in a twofold Cadogan cyclization followed by double N-methylation. The crystal structure is characterized by a zigzag arrangement of centrosymmetric molecules. The indolocarbazole framework is essentially planar [maximum deviation = 0.028 (2) ] and the methoxy groups are orthogonal to this plane [C—C—O—C torsion angle = 88.2 (2)°]. The lengths of the C—N bonds are nearly identical and all C—C bonds of the pyrrole subunit are significantly longer than the C—C bonds in the benzene rings.
经典Ramsey数R(4,12),R(5,11)和R(5,12)的新下界  [PDF]
科学通报 , 1997,
Abstract: 已知经典Ramsey数R(m,n)(m,n≥2)是一定存在的,但确定经典Ramsey数R(m,n)是组合数学和图论中著名的难题,至今在理论和方法上尚未见到取得突破的迹象,因此近年来各国学者主要用各种方法借助计算机对一些具体的Ramsey数给出估计。王清贤、谢继国等人沿用文献[4]的方法研究一般的循环图,得到一些Ramsey数的下界。这种方法在用字典排列法产生参数时,由于大量同构的图均要一一考察,占用大量计算机机时。因此我们作出新的尝试利用素数阶循环图的平移和旋转等性质改进了产生参数的方法,提高了运算效率,得到3个Ramsey数的新下界。
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