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791.
Supercritical multicomponent fluid thermodynamics are often built from equations of state. We investigate mathematically such a construction of a Gibbsian thermodynamics compatible at low density with that of ideal gas mixtures starting from a pressure law. We further study the structure of chemical production rates obtained from nonequilibrium statistical thermodynamics. As a typical application, we consider the Soave-Redlich-Kwong cubic equation of state and investigate mathematically the corresponding thermodynamics. This thermodynamics is then used to study the stability of H2-O2-N2 mixtures at high pressure and low temperature as well as to illustrate the role of nonidealities in a transcritical H2-O2-N2 flame. 相似文献
792.
Lionel Mathelin Luc Pastur Olivier Le Ma?tre 《Theoretical and Computational Fluid Dynamics》2012,26(1-4):319-337
We present a method that seeks to combine the properties of optimal control with the robust character of closed-loop control. The method relies on the availability of a reduced model of the system to be controlled, in order to express the control problem in a low-dimensional space where the system-state-dependent optimal control law is subsequently approximated in a preprocessing stage. A polynomial expansion is used for the approximation, enabling fast update of the optimal control law each time a new observation of the system state is made available. It results in a real-time compatible, efficient (optimal-like), and robust control strategy. A compressed-sensing approach is proposed to efficiently construct the approximate control law, exploiting the compressible character of the optimal control law in the retained approximation basis. The method is demonstrated for the control of the flow around a cylinder and is shown to perform as well as the much more costly receding-horizon optimal control approach, where the exact optimal control problem is actually recomputed, even in the presence of large aleatoric perturbations. Potential and remaining issues toward application to larger dimensional reduced systems are also discussed, and some directions for improvement are suggested. 相似文献
793.
794.
795.
Mayur Shah Kannappan Thangaraj Mou-Ling Soong Lionel T. Wolford Joseph H. Boyer Ieva R. Politzer Theodore G. Pavlopoulos 《Heteroatom Chemistry》1990,1(5):389-399
Condensations between 3-X-2,4-dimethylpyrroles (X = H, CH3, C2H5, and CO2C2H5) and acyl chlorides gave derivatives of 3,5,3′,5′-tetramethylpyrromethene (isolated as their hydrochloride salts): 6-methyl, 6-ethyl, 4,4′,6-trimethyl, 4,4′-diethyl-6-methyl, and 4,4′-dicarboethoxy-6-ethyl derivatives for conversion on treatment with boron trifluoride to 1,3,5,7-tetramethylpyrromethene–BF2 complex (TMP–BF2) and its 8-methyl (PMP–BF2), 8-ethyl, 2,6,8-trimethyl (HMP–BF2),2,6,-diethyl-8-methyl (PMDEP–BF2), and 2,6-dicarboethoxy-8-ethyl derivatives. Chlorosulfonation converted, 1,3,5,7,8-pentamethylpyrromethene–BF2 complex to its 2,6-disulfonic acid isolated as the lithium, sodium (PMPDS–BF2), potassium, rubidium, cesium, ammonium, and tetramethylammonium disulfonate salts and the methyl disulfonate ester. Sodium 1,3,5,7-tetramethyl-8-ethylpyrromethene-2,6-disulfonate–BF2 complex was obtained from the 8-ethyl derivative of TMP–BF2. Nitration and bromination converted PMP–BF2 to its 2,6-dinitro-(PMDNP–BF2) and 2,6-dibromo- derivatives. The time required for loss of fluorescence by irradiation from a sunlamp showed the following order for P–BF2 compounds (10−3 to 10−4 M) in ethanol: PMPDS–BF2, 7 weeks; PMP–BF2, 5 days; PMDNP–BF2, 72 h; HMP–BF2, 70 h; and PMDEP–BF2, 65 h. Under similar irradiation PMPDS–BF2 in water lost fluorescence after 55 h. The dibromo derivative was inactive, but each of the other pyrromethene–BF2 complexes under flashlamp excitation showed broadband laser activity in the region λ 530–580 nm. In methanol PMPDS–BF2 was six times more resistant to degradation by flashlamp pulses than was observed for Rhodamine-6G (R-6G). An improvement (up to 66%) in the laser power efficiency of PMPDS–BF2 (10−4 M in methanol) in the presence of caffeine (a filter for light <300 nm) was dependent on flashlamp pulse width (2.0 to 7.0 μsec). 相似文献
796.
797.
798.
Govindarao Sathyamoorthi Lionel T. Wolford Anthony M. Haag Joseph H. Boyer 《Heteroatom Chemistry》1994,5(3):245-249
Treatment with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) oxidized 2,6-diethyl-1,3,5,7,8-pentamethylpyrromethene–BF2 complex 1 , 13,14-trimethyl-2, 3, 4, 5,9,10,11,12-octahydroindomethene–BF2 complex 5 , and 1,3,5,7,8-pentamethyl-1,2,3,5,6,7-hexahydropyromethene–BF2 complex 8 to the weakly fluorescent 3-formyl, 5-oxo, and 8-formyl derivatives 4 , 6 , and 9 , respectively. The dye 1 was oxidized by lead tetraacetate to 1,7,8-trimethyl-2,6-diethyl-3,5-diacetoxymethylpyrromethene–BF2 complex 12 [λf (ethanol) 538 nm, Φ 0.62, λlas (ethanol) 555–570 nm]. Catalytic reduction (Pd/C) converted the aldehyde 4 to 2,6-diethyl-3-hydroxymethyl-1,5,7,8-tetramethylpyrromethene–BF2 complex 10 [λf (ethanol) 537 nm, Φ 0.70, λlas (ethanol) 547–575 nm]. 相似文献
799.
800.
Yu Chen Zhong Shen Lionel Gehringer Holger Frey Salah‐Eddine Stiriba 《Macromolecular rapid communications》2006,27(1):69-75
Summary: Supramolecular interaction of fully methylated hyperbranched polyethylenimines (PEI) with a mesogen‐based carboxylic acid, 5‐(p‐cyanobiphenoxy)pentanoic acid, results in the formation of supramolecular complexes exhibiting thermotropic liquid crystalline (LC) mesophases. In contrast to the common smectic mesophases of most dendritic LC polymers, nematic LC phases were observed. The complexation of PEI and the mesogen units is due to electrostatic interaction between the carboxylate groups and the ammonium end groups of PEI. LC properties were investigated by a combination of differential scanning calorimetry, polarizing light optical microscopy, and X‐ray diffractometry.