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71.
D Chakravorty 《Journal of Non》1974,15(2):191-198
Electrically conducting layers have been induced in some alkali-containing silicate glasses by subjecting them to a Na+?Ag+ ion-exchange reaction followed by a reduction treatment in hydrogen. The surface resistances of the ion-exchanged and reduced glasses range from 0.15ohm/square to 4.1 ohm/square depending on the glass composition. Most of the layers give TCR values around 2000 ppm/K. The microstructural studies of the ion-exchanged and reduced layers confirm that such high surface conductances arise due to the formation of continuous chains of metallic silver and bismuth droplets in a glass matrix. 相似文献
72.
Arghya Chakravorty Emilio Gallicchio Emil Alexov 《Journal of computational chemistry》2019,40(12):1290-1304
A novel grid-based method is presented, which in conjunction with a smooth Gaussian-based model of atoms, is used to compute molecular volume (MV) and surface area (MSA). The MV and MSA are essential for computing nonpolar component of free energies. The objective of our grid-based approach is to identify solute atom pairs that share overlapping volumes in space. Once completed, this information is used to construct a rooted tree using depth-first method to yield the final volume and SA by using the formulations of the Gaussian model described by Grant and Pickup (J. Phys Chem, 1995, 99 , 3503). The method is designed to function uninterruptedly with the grid-based finite-difference method implemented in Delphi, a popular and open-source package used for solving the Poisson–Boltzmann equation (PBE). We demonstrate the time efficacy of the method while also validating its performance in terms of the effect of grid-resolution, positioning of the solute within the grid-map and accuracy in identification of overlapping atom pairs. We also explore and discuss different aspects of the Gaussian model with key emphasis on its physical meaningfulness. This development and its future release with the Delphi package are intended to provide a physically meaningful, fast, robust and comprehensive tool for MM/PBSA based free energy calculations. © 2019 Wiley Periodicals, Inc. 相似文献
73.
We extend the Clauser-Horne formulation of Bell-type inequality for the correlated pair of decaying and oscillating (neutral pseudo-scalar) meson-antimesons, using a few supplementary assumptions. The quantum-mechanical predictions for the B0- \(\bar B^0 \) system do lead to violations of this inequality under certain conditions. Further work is called for to investigate the possibility of dispensing with the supplementary assumptions. 相似文献
74.
Sudeshna Chakravorty A. Roy Chowdhury S. N. Paul 《International Journal of Theoretical Physics》1992,31(2):343-352
We analyze the effect of a nonzero streaming velocity of both positive and negative ions on the formation of solitary waves in a relativistic plasma. The thermodynamic situation is considered to be isothermal. For various values ofu
0/C andn
o/nowe obtain the variations of the amplitude and the width of the solitary wave. 相似文献
75.
76.
77.
Chattopadhyay Shyamal Kumar Mitra Kamala Biswas Subhendu Naskar Subhendu Mishra Dipankar Adhikary Bibhutosh Harrison Roger G. Cannon John F. 《Transition Metal Chemistry》2004,29(1):1-6
Reaction of 1-phenyl 5-(aminophenyl) 9-(2-pyridyl) benzimidazole derivatives (2) with cis-Ru(bpy)2Cl2 in MeCN results in the formation of N-(aryl) imidazo[1,5a] pyridine derivatives (4) and cis-[Ru(bpy)2(MeCN)2]2+
(5). Crystal structures of N-(4-chlorophenyl) imidazo[1,5a] pyridine (4b) and cis-[Ru(bpy)2(MeCN)2](ClO4)2
(5) are also reported. 相似文献
78.
The concerned azooximes (L1OH, 1) are of type p-X-C6H4C(N2Ph)(NOH) (X = H, Me, Cl). The reaction of [Re(MeCN)Cl3(PPh3)2] with [Ag(L1OH)(L1O)] in cold dichloromethane-acetonitrile solvent has furnished the green colored ionized azoimine complex [ReV(O)Cl(PPh3)2(L1)](PF6), 2. In effect L1O- has undergone oxidative addition, the oxygen atom being transferred to the metal site. Upon treatment of [ReV(NPh)Cl3(PPh3)2] with L1OH in solution, the neutral azoimine complex [ReV(NPh)Cl3(L1H)], 3, resulted due to the spontaneous transfer of the oxime oxygen atom to a PPh3 ligand, which is eliminated as OPPh3. In contrast, the oxime of 2-acetylpyridine (L2OH, 4) did not undergo oxygen atom transfer and simply afforded the imine-oxime complex [ReV(NC6H4Y)Cl2(PPh3)(L2O)], 5, upon reacting with [ReV(NC6H4Y)Cl3(PPh3)2] (Y = H, Me, Cl). The spectral and electrochemical properties of 2, 3, and 5 and the structures of three representative compounds are reported. In the cation of 2 (X = H) the two PPh3 ligands lie trans to each other and the equatorial plane is defined by the five-membered azoimine chelate ring and the oxo and chloro ligands. The oxo ligand which forms a model triple bond (Re-O length 1.616(6) A) lies cis to the imine-N atom. In 3 (X = Cl) the ReCl3 fragment has meridional geometry and the imido nitrogen lies trans to the imine nitrogen of the planar azoimine chelate ring. In 5 x H2O (Y = Me), the Cl, oximato-N, and P atoms define an equatorial plane and the pyridine-N lies trans to the imido-N. The water of crystallization is hydrogen bonded to the oximato oxygen atom (O...O, 2.829(5) A). Reaction models in which chelation of the azooxime precedes oxygen atom transfer are proposed on the basis of oxophilicity of trivalent rhenium, Lewis acid activity of pentavalent rhenium, electron withdrawal by the azo group, and observed relative disposition of ligands in products. 相似文献
79.
Senjuti De Michael G. B. Drew David W. Price Samik Nag Dipankar Datta 《International journal of quantum chemistry》2007,107(1):182-188
G3B3 and G2MP2 calculations using Gaussian 03 have been carried out to investigate the protonation preferences for phenylboronic acid. All nine heavy atoms have been protonated in turn. With both methodologies, the two lowest protonation energies are obtained with the proton located either at the ipso carbon atom or at a hydroxyl oxygen atom. Within the G3B3 formalism, the lowest‐energy configuration by 4.3 kcal · mol?1 is found when the proton is located at the ipso carbon, rather than at the electronegative oxygen atom. In the resulting structure, the phenyl ring has lost a significant amount of aromaticity. By contrast, calculations with G2MP2 show that protonation at the hydroxyl oxygen atom is favored by 7.7 kcal · mol?1. Calculations using the polarizable continuum model (PCM) solvent method also give preference to protonation at the oxygen atom when water is used as the solvent. The preference for protonation at the ipso carbon found by the more accurate G3B3 method is unexpected and its implications in Suzuki coupling are discussed. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 相似文献
80.
A. K. Chakravorty 《Journal of Thermal Analysis and Calorimetry》1993,39(3):289-299
TMA/DTMA with DTA studies on the thermal changes of kaolinite were performed with special emphasis on the crystallization behaviour of amorphous SiO2. The results of four different physical techniques (semiquantitative XRD, DTA, TMA and DTMA) were clearly in good agreement with the fact that the 1420°C exotherm in DTA is due to silica crystallization.Thanks to Dr. B. K. Sarkor, Director of the Institute for his kind permission to publish the paper and to Mr. D. K. Ahosh for his needful suggestions. 相似文献