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排序方式: 共有104条查询结果,搜索用时 93 毫秒
1.
Lourdes Callau Marta Giamberini Jos Antonio Reina Ana Mantecn 《Journal of polymer science. Part A, Polymer chemistry》2006,44(6):1877-1889
The synthesis of two vinyl‐terminated side‐chain liquid‐crystalline polyethers containing benzylideneaniline moieties as mesogenic cores was approached in two different ways: by chemically modifying poly(epichlorohydrin) with suitable mesogenic acids or by polymerizing analogous glycidyl ester or glycidyl ether derivatives. In all the conditions tested, the first approach led to materials in which the imine group was hydrolyzed. The second approach led to the desired polymers PG2a and PG2b , but only from the glycidyl ether derivatives and when the initiator was the system that combined polyiminophosphazene base t‐Bu‐P4 and 3,5‐di‐t‐butylphenol. These polymers were chemically characterized by IR and 1H and 13C NMR spectroscopies. The estimated degrees of polymerization ranged from 30 to 36. The liquid crystalline behavior of the synthesized polymers was studied by differential scanning calorimetry, polarized optical microscopy (POM) and X‐ray diffraction. Both polymers behave like liquid crystals and exhibited a single mesophase, which was recognized as a smectic C mesophase, probably with a bilayer arrangement, i.e., a smectic C2 mesophase. The crosslinking of both polymers was performed with dicumyl peroxide as initiator, which led to liquid crystalline thermosets. POM and X‐ray diffraction confirmed that the mesophase organization mantained on the crosslinked materials. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1877–1889, 2006 相似文献
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We use a quite concrete and simple realization of sl
q
(2, ) involving finite difference operators. We interpret them as derivations (in the noncommutative sense) on a suitable graded algebra, which gives rise to the noncommutative scheme 1 II 1* as the counterpart of the standard 1 = Sl(2, )/B. 相似文献
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Lourdes Callau Ana Mantecn Jos Antonio Reina 《Journal of polymer science. Part A, Polymer chemistry》2002,40(14):2237-2244
We performed the crosslinking of vinyl‐terminated biphenyl and naphthalene side‐chain liquid‐crystalline polyethers using peroxide‐type initiators with and without the addition of tertiary amine promoters. The crosslinking temperatures were chosen in the range of mesophase stability to allow the mesophase order to be frozen. The biphenyl derivatives, with a high isotropization temperature, were crosslinked to a large extent. This led to anisotropic thermosets. To crosslink naphthalene derivatives, amine promoters were needed, but degrees of crosslinking were lower, and anisotropic elastomers were obtained. Crosslinking processes were studied by differential scanning calorimetry, polarized optical microscopy, and Fourier transform infrared spectroscopy. The nature of the frozen mesophase was confirmed by X‐ray diffraction studies on mechanically oriented samples. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2237–2244, 2002 相似文献
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Thermogravimetric study of the pyrolysis of waste wood 总被引:6,自引:0,他引:6
A thermogravimetric study of the pyrolysis of three different types of waste wood (forest wood, old furniture and used pallets) is carried out in a TGA equipment using dynamic and isothermal techniques. Isothermal runs were carried out at two temperature levels, one between 225° and 325°C (low range) and the other, between 700° and 900°C (high range). Results show a good agreement between the kinetic parameters obtained from either dynamic or isothermal techniques. It must be remarked that the own chemical composition of each type of wood together with the compounds added to the wood for each application, play a fundamental role in the kinetic behavior of their thermal decomposition. 相似文献
7.
Montserrat Ferrer Anna Juli Roser Reina Oriol Rossell Miquel Seco Dominique de Montauzon 《Journal of organometallic chemistry》1998,560(1-2)
Treatment of [(ClAu)2(diphosphine)] {diphosphine=bis(diphenylphosphino)methane (dppm), bis(diphenylphosphino)isopropane (dppip), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp)} with two equivalents of the anion [Fe2(μ-CO)(CO)6(μ-PPh2)]− in the presence of TlBF4 gives the new heterometallic diclusters [{Fe2(μ-CO)(CO)6(μ-PPh2)Au}2(diphosphine)] that have been isolated and characterized. Their 31P-NMR spectra show different patterns as a function of the diphosphine ligand. The electrochemical behavior of these compounds has been investigated and compared with that of the mono- [Fe2(μ-CO)(CO)6(μ-PPh2)(μ-AuPPh3)] and tricluster [{Fe2(μ-CO)(CO)6(μ-PPh2)Au}3(triphos)] derivatives. 相似文献
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Ando K Tsuji E Ando Y Kunitomo J Kobayashi R Yokomizo T Shimizu T Yamashita M Ohta S Nabe T Kohno S Ohishi Y 《Organic & biomolecular chemistry》2005,3(11):2129-2139
Variable benzo[b]furan derivatives having (E)- and (Z)-2-alkylcarbamoyl-1-methylvinyl groups at the 2-, 4- and 5-positions and a carboxylpropoxy or (1-phenyl)ethoxy group at the 7-position were prepared to find novel and selective leukotriene B4(LTB4) receptor antagonists. (E)-2-(2-diethylcarbamoyl-1-methylvinyl)-7-(1-phenylethoxy)benzo[b]furan (4v) showed selective inhibition to the human BLT2 receptor (hBLT2). On the other hand, (E)-2-acetyl-4-(2-diethylcarbamoyl-1-methylvinyl)-7-(1-phenylethoxy)benzo[b]furan (7v) inhibited both human BLT(1) receptor (hBLT1) and hBLT2. The (E)-2-(2-diethylcarbamoyl-1-methylvinyl) group lay on approximately the same plane as the benzo[b]furan ring, whereas the (E)-4-(2-diethylcarbamoyl-1-methylvinyl) group had the torsion angle (45.7 degree) from the benzo[b]furan ring plane. However, the (Z)-(2-alkylcarbamoyl-1-methylvinyl)benzo[b]furans were inactive. The inhibitory activity depended on the conformation of the 2-diethylcarbamoyl-1-methylvinyl group. 相似文献
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Miguel Reina Eduardo Gabriel Guzmán-López Annia Galano 《International journal of quantum chemistry》2023,123(2):e27011
A set of new rasagiline derivatives is presented. They were designed to be antioxidant compounds with the potential to be used for treating neurodegenerative disorders. They are expected to be multifunctional molecules that can help reduce oxidative stress, which is thought to contribute to neurodegenerative disorders. The CADMA-Chem computational protocol was used to produce rasagiline derivatives and to evaluate their likeliness as oral drugs and antioxidants. Three of them were identified as the most promising ones. They are proposed to be better free radical scavengers than rasagiline. In addition, they are expected to keep the parent's molecule neuroprotective capability. Hopefully, the results presented here would promote further experimental and theoretical investigations on these compounds. 相似文献