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121.
Osamu Nishizawa Hideki Misaka Toyoji Kakuchi Toshifumi Satoh 《Journal of polymer science. Part A, Polymer chemistry》2008,46(4):1185-1191
Norbornene polymerization using the commercially available and inexpensive catalyst system, cyclopentadienylzirconium trichloride (CpZrCl3) and isobutyl‐modified methylaluminoxane (MMAO), were carried out over a wide range of polymerization temperatures and monomer concentrations. For the CpZrCl3 catalyst system activated by aluminoxane with a 40 mol % methyl group and a 60 mol % isobutyl group (MMAO40/60), the polymerization temperature and monomer concentration significantly affected the molecular weight (Mn) of the obtained polymer and the catalytic activity. With an increase in the polymerization temperature from 0 to 27 °C, the catalytic activity and Mn increased, but these values dramatically decreased with the increasing polymerization temperature from 27 to 70 °C, meaning that the most suitable temperature was 27 °C. The CpZrCl3/MMAO40/60 ([Al]/[Zr] = 1000) catalyst system with the [NB] of 2.76 mol L?1 at 27 °C showed the highest activity of 145 kg molZr?1 h?1 and molecular weight of 211,000 g mol?1. The polymerization using the CpZrCl3/MMAO40/60 catalyst system proceeds through the vinyl addition mechanism to produce atactic polynorbornene, which was soluble in chloroform, toluene, and 1,2‐dichlorobenzene, but insoluble in methanol. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1185–1191, 2008 相似文献
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124.
Simon G. Bott Alan P. Marchand Jennifer Bolin Dongxia Xing L. Kathleen Talafuse 《Journal of chemical crystallography》1995,25(10):657-660
Racemicendo-5-acetyl-1,2,3,4-tetrachloro-7,7-dimethoxynorborn-2-ene was stereoselectively reduced by sodium borohydride to give only theS,S orR,R diastereomers. The crystal structure of the product displays no unusual features. 相似文献
125.
Modular In Situ Functionalization Strategy: Multicomponent Polymerization by Palladium/Norbornene Cooperative Catalysis
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Ki‐Young Yoon Prof. Dr. Guangbin Dong 《Angewandte Chemie (International ed. in English)》2018,57(28):8592-8596
Herein, we report a cooperatively palladium/norbornene‐catalyzed polymerization, which simplifies the synthesis of functional aromatic polymers, including conjugated polymers. Specifically, an A2B2C‐type multicomponent polymerization that is based on an ortho amination/ipso alkynylation reaction was developed for the preparation of various amine‐functionalized arylacetylene‐containing polymers. Within a single catalytic cycle, the amine side chains are site‐selectively installed in situ by C?H activation during the polymerization process, which represents a major difference from conventional cross‐coupling polymerizations. This “in situ functionalization” strategy enables the modular incorporation of functional side chains starting from simple monomers, thereby conveniently affording a diverse range of functional polymers. 相似文献
126.
Kinetics of the Same Reaction Monitored over Nine Orders of Magnitude in Concentration: When Are Unique Subensemble and Single‐Turnover Reactivity Displayed?
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Dr. Quinn T. Easter Prof. Suzanne A. Blum 《Angewandte Chemie (International ed. in English)》2018,57(37):12027-12032
Essentially no information is known about the behavior of individual molecular catalysts under reaction conditions. This is a result of the averaging inherent to traditional analytical techniques. Herein, a combined fluorescence microscopy and 1H NMR spectroscopy study reveals that unique (that is, non‐ensemble averaged) distributions and time‐variable kinetics from molecular ruthenium catalysts within growing polynorbornene occur and are detectable between 10?9 m and 10?6 m of substrate, surprisingly just 1000‐fold less concentrated than a typical laboratory bench‐scale reaction. The kinetic states governing single‐turnover events are determinable by overlay of the signal arising from individual monomer insertion reactions with that from polymer growth from neighboring catalysts. 相似文献
127.
Dense films of poly(vinyltrimethyl silane) (PVTMS) and poly(trimethylsilyl norbornene) (PTMSNB) having different thicknesses in the range l = 5–150 μm were cast from hydrocarbon solutions. It was shown that a density is inversely proportional to the film thickness. The following equation holds for the density ?: 1/? = 1/?0 − b/l. Permeability and diffusion coefficients were determined using the time lag method in respect to different gases. For all the gases, diffusion coefficients decrease when film thickness decreases and film density increases. A correlation of diffusion coefficients with fractional free volume were demonstrated. On the other hand, permeability coefficients are nearly independent of the thickness and density. Possible mechanisms of this behavior are discussed. 相似文献
128.
P. Eychenne E. Perez I. Rico M. Bon A. Lattes A. Moisand 《Colloid and polymer science》1993,271(11):1049-1054
Polymerization of norbornene using PdCl2 as catalyst is generally carried out at high temperatures in the absence of solvent. Low yields of polymer with relatively undefined molecular weights are obtained under these conditions. We describe the first example of polymerization of norbornene in water dispersion or aqueous emulsions catalyzed by PdCl2. Good yields of polymers and oligomers were obtained. Furthermore, in aqueous emulsions, novel microlatex which cannot be obtained by radical or ionic routes were synthesized, with particles sizes (10 nm.) generally only observed in microemulsion polymerizations.The stereochemistry of the polymers of low molecular weight was partially elucidated by13C NMR. 相似文献
129.
本文合成了两个新的催化剂,苯基-三苯基膦-[N-萘基-3-甲基水杨醛亚胺]合镍(4a)与苯基-三苯基膦-[N-萘基-5-硝基水杨醛亚胺]合镍(4b),并研究了它们催化降冰片烯的聚合。发现两种催化剂在助催化剂甲基铝氧烷(MAO)存在下都具有良好的催化降冰片烯聚合物活性。在50 ℃时,催化剂4b表现出最高催化活性。 相似文献
130.
N. V. Zyk E. K. Beloglazkina V. S. Tyurin Yu. K. Grishin 《Russian Chemical Bulletin》1998,47(11):2220-2225
Bromochlorination of norbornene whose chemo- and regio-selectivity is determined by the type of the halogenating reagent used
was studied. Three isomeric bromochloronorbornanes (2-endo-bromo-3-exo-chloro-, 2-exo-bromo-3-endo-chloro-, and 2-exo-bromo-7-syn-chlorobicyclo[2.2.1.]heptanes), 2-exo-7-syn- and 2-exo-7-anti-dibromo- and-dichloronorbornanes, and 2-bromonortricyclane were isolated and characterized by1H and13C NMR spectra. The spectral and structural characteristics of the resulting compounds are discussed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2290–2295, November, 1998. 相似文献