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551.
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553.
Electro-optic effects are observed in the smectic C states of 4-n-heptyloxybenzoic acid, 4-n-octyloxybenzoic acid. 4,4′-bis-n-heptyloxyazoxybenzene, and 4-n-decyloxy cinnamic acid under the application of an external ac electric field. The stripe domain pattern is observed for all the compounds studied above the first threshold. In the smectic C state there exists a second threshold at which the direction of the domain lines changes. 相似文献
554.
555.
Nobuhiro Kihara Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1993,31(11):2765-2773
Bis(cyclic Carbonate)s 1 were prepared by the reaction of bis(epoxide)s and atmospheric pressure of CO2 in the presence of sodium iodide and triphenylphosphine as catalysts at 100°C in high yield. Polyaddition of 1 and hexamethylenediamine ( 2a ) or dodecamethylenediamine ( 2b ) in dimethylsulfoxide or N,N-dimethylacetamide (DMAc) at 70 or 100°C for 24 h afforded corresponding poly(hydroxyurethane)s with M?n 20,000–30,000. When ethylenediamine ( 2c ) or 1,3-propanediamine ( 2d ) was used as a diamine, poly(hydroxyurethane)s with lower molecular weight were obtained. The presence of water, methanol, or ethyl acetate in the solvent had little effect on the M?n of the polymer obtained, because of the high chemoselectivity of the reaction of the five-membered cyclic carbonate and amine. Polyaddition of bis(cyclic carbonate) bearing ester groups and 2a also afforded the corresponding poly(hydroxyurethane) without aminolysis of the ester groups. Poly(hydroxyurethane) 3 obtained from the bis(cyclic carbonate) derived from bisphenol A was less soluble in organic solvents than model polyurethane 8 having no hydroxy groups obtained from 4,4′-isopropylidenebis(2-hydroxyethoxybenzene) and hexamethylene diisocyanate, and was thermally stable as well as 8.3 easily undertook crosslinking at room temperature by the treatment with hexamethylene diisocyanate or aluminium triisopropoxide in DMAc or tetrahydrofuran. The gel crosslinked by aluminium triisopropoxide regenerated the original polymer at room temperature by treatment with 1.5 equiv of 1.2M HCl in N-methylpyrollidinone for 1 h. © 1993 John Wiley & Sons, Inc. 相似文献
556.
Kumemura T Choshi T Hirata A Sera M Takahashi Y Nobuhiro J Hibino S 《Chemical & pharmaceutical bulletin》2005,53(4):393-397
A total synthesis of a new furo[3,2-h]isoquinoline alkaloid TMC120-B (2), isolated from Aspergillus ustus together with two related compounds, has been completed in sixteen steps. The key step is the synthesis of the appropriate 3,7,8-trisubstituted isoquinoline framework (23) based on a thermal electrocyclic reaction of the 1-aza 6pi-electron system involving the benzene double bond. In addition, the microwave assisted electrocyclic reaction of this system was newly performed. 相似文献
557.
An improved algorithm is presented for rapid calculation of the hessian matrix for the conformational energy of a protein as a function of only dihedral angles. The speed of the calculation, which is about one order faster than by the previous method, is achieved by two considerations. First, the algorithm is designed to take advantage of the supercomputer pipeline architecture. Second, long-range, nonbonded interactions are cut off and long-range electrostatic interactions are approximated by dipole-dipole interactions in order to reduce the number of pairwise interactions that have to be computed. The results of benchmark tests of the program are given as applied for four globular proteins of different sizes. 相似文献
558.
The meta-substituted polyketones 1b - f, including the parent ketone 1a, afforded approximately similar values for the quantum yield of benzocyclobutenol formation (ΦCB), the triplet lifetime (τ), ET and λmax, respectively. In contrast, ΦCB, τ, ET, and λmax of the para-substituted polyketones 2a - c depended on their molecular structures. 相似文献
559.
Nobuhiro Kanomata Satoshi MaruyamaKatsuhito Tomono Shinnosuke Anada 《Tetrahedron letters》2003,44(18):3599-3603
A facile and practical removal of 2-oxazolidinone and 2-hydroxyethylamine auxiliaries was accomplished by treating the corresponding N-acyl-2-oxazolidinone and N-(2-hydroxyethyl)amide derivatives in simple methoxide-carbonate systems. The presence of excess DMC (dimethyl carbonate) accelerates the N-acyl bond cleavage for those substrates under mild reaction conditions, and the present method was found to be useful especially for the synthesis of planar-chiral nicotinate. 相似文献
560.
Nobuhiro Kuwahara Kazuyoshi Ogino Makoto Konuma Noriko Iida Motozo Kaneko 《Journal of Polymer Science.Polymer Physics》1966,4(2):173-181
The relationship of intrinsic viscosity to the number-average molecular weight has been obtained for poly-3,4-dichlorostyrene and poly-p-cyclohexylstyrene in a few solvents. Values of (〈L2〉0/M)1/2 have been estimated for poly-3,4-dichlorostyrene and poly-p-cyclohexylstyrene through the use of the treatment of Stockmayer and Fixman. The values of (〈L〉0/M)1/2 have been obtained as 2.18 ± 0.08 and 2.52 ± 0.07 for poly-3,4-dichlorostyrene and poly-p-cyclohexylstyrene, respectively. The σ value of a series of polystyrene derivatives has been found to increase with the bulk of side groups. This seems to indicate that the σ value is mainly determined by the steric repulsion between side groups. 相似文献