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排序方式: 共有129条查询结果,搜索用时 15 毫秒
1.
Minna GünesÛ Jussi Valkonen 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(9):i119-i120
Caesium tetrasilver dizinc nonathiocyanate, Cs[Ag4Zn2(SCN)9], forms a continuous structure, where the Ag atoms and the S atoms of the thiocyanate groups form chains which run along [101]. These chains are bonded together through the Cs and Zn atoms. It is not possible to distinguish between space groups P1 and P, but, if the latter space group is correct, the structure contains a thiocyanate group disordered across a centre of inversion. The structure is described in space group P, in which the Cs atom also lies on a centre of inversion. 相似文献
2.
Medical grade PVC plasticised with polycaprolactone–polycarbonate (PCL–PC) was subjected to aqueous environments at different temperatures. The release profile during ageing was determined by solid phase microextraction (SPME) and GC–MS. At the same time changes in the surface composition due to, for example, migration of PCL–PC from the blend were followed by FTIR. Almost no changes in the material or its surface composition were observed during 98 days at 37 °C in water or phosphate buffer. Only trace amount of 6-hydroxyhexanoic acid the final hydrolysis product of PCL–PC was detected in the GC–MS chromatograms and the weight loss was negligible. Even when the ageing temperature was raised to 70 °C only minor increase in the amount of 6-hydroxyhexanoic acid was observed and the weight loss after 98 days was under 1%. Changes in the FTIR spectra indicating migration of PCL–PC towards the surface of the PVC/PCL–PC tubing were observed first after 70 days at 70 °C. Large increase in the hydrolysis rate of PCL–PC and almost complete depletion of PCL–PC from the blend was observed when the ageing temperature was raised to 100 °C. 相似文献
3.
报道了深圳市南山区714名0 ̄6岁儿童头发中6种必需微量和宏量元素的水平,分析了不同年龄、性别儿童6种元素的异常状况,研究结果表明,儿童头发中锌、铜、铁、钙和锰元素缺乏状况相当严重总缺乏率占89.9%。 相似文献
4.
5.
A One‐Pot Synthesis of N‐Aryl‐2‐Oxazolidinones and Cyclic Urethanes by the Lewis Base Catalyzed Fixation of Carbon Dioxide into Anilines and Bromoalkanes 下载免费PDF全文
Teemu Niemi Dr. Jesus E. Perea‐Buceta Dr. Israel Fernández Otto‐Matti Hiltunen Vili Salo Sari Rautiainen Dr. Minna T. Räisänen Prof. Timo Repo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(30):10355-10359
The multicomponent assembly of pharmaceutically relevant N‐aryl‐oxazolidinones through the direct insertion of carbon dioxide into readily available anilines and dibromoalkanes is described. The addition of catalytic amounts of an organosuperbase such as Barton's base enables this transformation to proceed with high yields and exquisite substrate functional‐group tolerance under ambient CO2 pressure and mild temperature. This report also provides the first proof‐of‐principle for the single‐operation synthesis of elusive seven‐membered ring cyclic urethanes. 相似文献
6.
Yi Ding Yan Wu Ying Tian Yuzeng Xu Minna Hou Bo Zhou Jingshan Luo Guofu Hou Ying Zhao Xiaodan Zhang 《Journal of Energy Chemistry》2021,(7):48-54
Guanidinium (GA) cations are intentionally introduced in MAPbl3 perovskite by considering its potential capability of stabilizing the material through plenty of... 相似文献
7.
Differential scanning calorimetry (DSC) is one of the most frequently used techniques for analyzing small concentrations of
amorphous phases in a crystalline matrix. In recent years novel enhanced DSC approaches have been intensively looked for to
improve parameters such as sensitivity, accuracy, and detection limit of the technique. Low levels of amorphous phases can
be quantitatively determined in DSC by measuring the heat capacity change associated with the glass transition. In this short
review the potentials provided by the HyperDSC and StepScan DSC techniques are discussed. Examples illustrate the advantages
and disadvantages of the techniques and compare their abilities to detect small glass transitions and determine low contents
of amorphous phases in samples which are mostly crystalline. 相似文献
8.
Johanna Andersson Dr. Minna Li Prof. Per Lincoln 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(36):11037-11046
The binuclear ruthenium complex [μ‐bidppz(phen)4Ru2]4+ has been extensively studied since the discovery of its unusual threading intercalation interaction with DNA, a binding mode with extremely slow binding and dissociation kinetics. The complex has been shown to be selective towards long stretches of alternating AT base pairs, which makes it interesting, for example, as a model compound for anti‐malaria drugs due to the high AT content of the genome of the malaria parasite P. falciparum. We have investigated the effect of bridging ligand structure on threading intercalation ability and found that length and rigidity as well as the size of the intercalated ring system are all factors that affect the rate and selectivity of the threading intercalation. In particular, we discovered a new DNA‐threading compound, [μ‐dppzip(phen)4Ru2]4+, which appears to be just at the border of being capable of threading intercalation and displays even greater selectivity for AT‐DNA than the parent compound, [μ‐bidppz(phen)4Ru2]4+. 相似文献
9.
Gimenez-Lopez Mdel C Räisänen MT Chamberlain TW Weber U Lebedeva M Rance GA Briggs GA Pettifor D Burlakov V Buck M Khlobystov AN 《Langmuir : the ACS journal of surfaces and colloids》2011,27(17):10977-10985
Anisotropy of intermolecular and molecule-substrate interactions holds the key to controlling the arrangement of fullerenes into 2D self-assembled monolayers (SAMs). The chemical reactivity of fullerenes allows functionalization of the carbon cages with sulfur-containing groups, thiols and thioethers, which facilitates the reliable adsorption of these molecules on gold substrates. A series of structurally related molecules, eight of which are new fullerene compounds, allows systematic investigation of the structural and functional parameters defining the geometry of fullerene SAMs. Scanning tunnelling microscopy (STM) measurements reveal that the chemical nature of the anchoring group appears to be crucial for the long-range order in fullerenes: the assembly of thiol-functionalized fullerenes is governed by strong molecule-surface interactions, which prohibit formation of ordered molecular arrays, while thioether-functionalized fullerenes, which have a weaker interaction with the surface than the thiols, form a variety of ordered 2D molecular arrays owing to noncovalent intermolecular interactions. A linear row of fullerene molecules is a recurring structural feature of the ordered SAMs, but the relative alignment and the spacing between the fullerene rows is strongly dependent on the size and shape of the spacer group linking the fullerene cage and the anchoring group. Careful control of the chemical functionality on the carbon cages enables positioning of fullerenes into at least four different packing arrangements, none of which have been observed before. Our new strategy for the controlled arrangement of fullerenes on surfaces at the molecular level will advance the development of practical applications for these nanomaterials. 相似文献
10.
Minna GünesÛ Jussi Valkonen 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(1):i1-i2
The title compound, dicaesium(I)‐μ‐thiocyanato‐κ2N:S‐zinc(II)‐tetra‐μ‐thiocyanato‐κ2S:N‐argentate(I), crystallizes in the orthorhombic space group Pmn21 and contains units of composition AgZn(SCN)3 lying on a mirror plane and bonded together through Cs+ ions and thiocyanate groups. The crystal studied contained equal numbers of inversion twins. 相似文献