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排序方式: 共有137条查询结果,搜索用时 15 毫秒
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采用溶液共混制备耻不同比例的热致液晶共聚酯/含酚酞侧基聚芳醚砜共混物。利用锥板流变仪对共混体系的熔体流变性能进行了初步研究,测定了熔体粘度-温度、粘度-剪切速度的关系,结果表明该液晶聚合物能明显降低聚芳醚砜的熔体粘度。 相似文献
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A series of novel mesogenic polyamides containing a flexible pendent side group wassynthesized by solution condensation polymerization. The new monomers, diacids and di-amines containing flexible elements of diferent lengths, were also synthesized and character-ized by ~1HNMR, mass spectroscopy and elemental analysis. The polymers were character-ized by viscosity measurements, differential scanning calorimetry (DSC), X-ray diffiactionand polarizing optical microscopy These studies revealed that polyamides containingflexible elements of a sufficient length exhibited thermotropic liquid crystalline(LC) pro-perties. The melting temperatures of this series of polymers were particularly sensitive tothe length of the flexible segment on the main chain and that of the flexible pendent esterside chain. Lyotropic LC behaviours were also observed in solution. 相似文献
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一类可纺丝的全芳香热致性液晶共聚酯的合成和表征 总被引:2,自引:0,他引:2
利用Higashi芳香聚酯直接缩聚法的原理 ,采用一步混合投料直接缩聚的方法 ,以对羟基苯甲酸(PHB)、间苯二甲酸 (MPA)、4 ,4′ 二羟基二苯酮 (DHBP)和对苯二酚 (HQ)为单体原料 ,合成了全芳香共聚酯 .该合成方法反应条件温和 ,简单易控 ,产物分子量高 .用差热分析 (DSC)、热重分析 (TA)、偏光显微镜 (PLM)、广角X 射线衍射 (WAXD)等测试分析手段对共聚酯的热性能和液晶特性进行了表征 .研究结果表明 ,利用此方法合成所得的聚合物呈明显的向列型热致液晶特性 ,热稳定性高 ,并具有极易成纤的特点 ,有望成为一种可用于纺丝的全芳香热致液晶共聚酯材料 相似文献
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热致液晶聚合物的可纺性与其在基体树脂中的成纤 总被引:6,自引:1,他引:6
热致液晶聚合物的可纺性与其在基体树脂中的成纤何嘉松,张洪志(中国科学院化学研究所工程塑料国家重点实验室北京100080)关键词热致液晶聚合物,熔融可纺性,高分子共混物,原位复合,亚微米增强用热致液晶聚合物(TLCP)对热塑性树脂产生亚微米级增强作用的... 相似文献
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Recent advances in the area of glycobiology have been paralleled by progress in our understanding of the physical properties of glycoglycerolipids (GGLs). These advances have been accelerated by interest in the new found roles of these simple glycolipids in nature, by advances in synthetic procedures, and by an interest in the technological application of a group of amphiphiles with unique physical and chemical properties. Here, we consider the phase properties of some GGL/water systems containing either a single hexopyranoside or pentopyranoside headgroup. Recent calorimetric and X-ray diffraction measurements of some GGL diastereomers suggest that both headgroup and interfacial hydration play a major role in determining both lyotropism and mesomorphic phase properties as the chemical structure of the lipid headgroup, interface and hydrocarbon chains are systematically altered. For GGLs of a given chain length, interactions between the headgroup/interface and water determine whether or not a highly ordered, lamellar crystalline phase is formed, the number of such phases and their rate of formation and, in some cases, the nature of the molecular packing of those phases. In the liquid crystalline phases, the hydrocarbon chains determine the area per molecule in the lamellar liquid crystalline phase, but it is the cross-sectional area of the hydrated headgroup and the penetration of water into the interface which determines the nature of the non-lamellar phases, probably through small changes in interfacial geometry as the lateral stresses in the headgroup region increase. 相似文献
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Polysulfone udel was chemically functionalized with chloromethylene functional groups via the chloromethylation reaction. A new azomethine dimesogen containing one phenolic hydroxyl functional group was recently synthesized and proved to exhibit a large nematic mesophase range in the liquid state. Further reaction of the dimesogen with the functionalized polysulfone using a transquaternization reaction led to new polysulfones bearing pendant rigid dimesogenic units--no spacer being involved in the chemical design of the polymer. The polymers were characterized by IR, 1H NMR spectroscopy techniques, and their thermotropic liquid crystallinity behaviour was studied by optical polarizing microscopy (PLM) and DSC measurements. Enantiotropic nematic mesophases were observed under the PLM. A dependence of the melting temperature on the degree of substitution was noticed. 相似文献