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61.
The effect of external forces on the initial dissociation of RDX (1,3,5‐trinitro‐1,3,5‐triazine): A mechanochemical study
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Guido Todde Sanjiv K. Jha Gopinath Subramanian 《International journal of quantum chemistry》2017,117(20)
Experimental and theoretical studies have proposed different initiation reactions for the decomposition of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX). Three primary reactions are considered to start RDX decomposition: homolytic N? N bond fission, HONO elimination, and concerted fission of C? N bonds. The focus of this article is to study the effect of external forces on the energy barrier and reaction energies of all three mechanisms. We used the Nudged Elastic Band method along with ab initio Density Functional Theory within the framework of a generalized force‐modified potential energy surface (G‐FMPES) to calculate the minimum energy paths at different compressive (corresponding to pressure between approximately 6 and 294 MPa) and expansive force values (between 10 and 264 pN). For all three reactions, the application of an expansive force increases the exothermicity and lowers the energy barriers to different extents, while a compressive force decreases the exothermicity and raises the energy barrier to different extents. 相似文献
62.
B. Leela Maheswara Rao Shaik Nowshuddin Anjali Jha Murali K. Divi M. N. A. Rao 《合成通讯》2017,47(22):2127-2132
A new reagent, tert-butyl (2,4-dioxo-3-azaspiro [5,5] undecan-3-yl) carbonate (Boc-OASUD) for the preparation of N-Boc-amino acids is described. The Boc-OASUD reacts with amino acids and their esters at room temperature in the presence of a base and gives N-Boc-amino acids and their esters in good yields and purity. Introduction of the Boc group takes place without racemization. The Boc-OASUD, being a solid and more stable, is a better alternative to di-tert-butyl dicarbonate which is low melting and has to be dispensed in plastic containers than glass because of its poor stability. 相似文献
63.
Enikö Kádár David M. Lowe Montserrat Solé Andrew S. Fisher Awadhesh N. Jha James W. Readman Thomas H. Hutchinson 《Analytical and bioanalytical chemistry》2010,396(2):657-666
Nano-Fe particle uptake was experimentally examined in vitro using excised gills and blood cells of the edible blue mussel
Mytilus sp. Whole gills were exposed to both Fe2O3 nanoparticles and a solution of the hydrated FeCl3 salt, for up to 12 h, and blood cells for 30 min. Equimolar Fe+3 in the nano- and the soluble form was estimated under the assumption of dense spherical particles accommodating the same
number of Fe+3 as in the dissolved salt solution, namely: 1,000 μg L−1 Fe2O3 equivalent to 100 μg L−1 FeCl3·6H2O. Putative toxic impact of nano-Fe in gill epithelia and blood cells was assessed by an array of techniques including light-
and electron microscopy, biomarkers for oxidative stress (lipid peroxidation levels), neurotoxic effects (acetylcholinesterase
activity) and cytotoxicity (neutral red retention). Total and filtered fractions (20 and 200 nm, respectively) of Fe were
analysed by ICP-OES. Our results provide evidence for the following: (1) much of both the soluble (95%) and the nano-Fe (90%)
were removed from the water column within 12 h; (2) dissolved- and nano-Fe seemed to follow different routes of uptake within
the gill epithelium; (3) both nano-Fe and soluble FeCl3 caused similar impairment of lysosomal stability in circulating blood cells; (4) lipid peroxidation in gills exposed to the
two distinct forms of Fe was increased, while acetylcholinesterase activity was unaffected. In these short-term in vitro studies,
there appears to be little difference in toxic response between exposure to the Fe salt and the nano-Fe indicating that, in
this case, the nanoparticles do not invoke special properties affecting biological function in gills. However, with the use
of nano-Fe as a food additive, clearly longer-term in vivo studies are warranted. 相似文献
64.
S. Dey J. P. Gewali A. K. Jha L. Chhaigte Y. S. Jain 《Indian Journal of Physics》2011,85(8):1309-1330
High resolution spectroscopy of doped molecules in 4He nano-droplets and clusters gives a signature of superfluidity in microscopic system, termed as microscopic superfluidity. Ro-vibrational spectrum of 4HeN-M clusters is studied with the help of some important observations, revealed from experiments (viz., localised and orderly arrangement of 4He atoms, although, being free to move in the order of their locations; individual 4He atoms can not be tagged as normal/ superfluid, etc.) and other factors (e.g., consideration that the 4He atoms which happen to fall in the plane of rotation of a molecule, render a equipotential ring and thus, do not take part
in rotation; etc.) which effect the rotational and vibrational spectrum of the system. This helps us in successfully explaining the experimental
findings which state that the rotational spectrum of clusters have sharp peaks (indicating that the molecule rotates like
a free rotor) and moment of inertia and vibrational frequency shift have a non-trivial dependence on N. 相似文献
65.
We study the effect of finite chemical potential for the QGP constituents in the Ramanathan et al. statistical model [Phys. Rev.
C70, 027903, (2004)]. While the earlier computations using this model with vanishing chemical potentials indicated a weakly first
order phase transition for the system in the vicinity of 170 MeV [Pramana
68 757 (2007)], the introduction of finite values for the chemical potentials of the constituents makes the transition a smooth
roll over of the phases, while allowing fireball formation with radius of a few ‘fermi’ to take place. This seems to be in
conformity with the latest consensus on the nature of the QGP-Hadron phase transition. 相似文献
66.
Bipin Singh Koranga Vinod Kumar A. Jha 《International Journal of Theoretical Physics》2011,50(8):2609-2613
We give a phenomenological model of CPT violating neutrino oscillation above the GUT scale. In this paper, we consider the
effect of Planck scale operators on neutrino mixing. We assume that the main part of neutrino masses and mixing arise through
GUT scale operators The dispersion relation for the CPT violating neutrino and anti-neutrino oscillation are discussed. 相似文献
67.
Venu MankadHimadri R. Soni Sanjeev K. GuptaPrafulla K. Jha 《Physica B: Condensed Matter》2011,406(19):3599-3604
We present results of first principles total energy calculations of the structure, electronic and lattice dynamics for beryllium semiboride and its three ternary alloys using generalized gradient and local density approximations under the framework of density functional theory. The generalized gradient approximation is used for all compounds except MgBeB using the Perdew-Burke-Ernzehorf exchange correlation functional while local density approximations use the Perdew-Zunger ultrasoft exchange correlation functional. The calculated ground state structural parameters are in good agreement with those of experimental and previous theoretical studies. The electronic band structure calculations show that Be2B may transform to a semiconductor after Al substitution. A linear response approach to density functional theory is used to calculate phonon dispersion curves and vibrational density of states. The phonon dispersion curves of Be2B and AlBeB are positive indicating a dynamical stablility of the structure for these compounds. The phonon dispersion curves of NaBeB and MgBeB show the imaginary phonons throughout the Brillouin zone, which confirms dynamical instability as indicated in band structures for these alloys. We also present the partial phonon density of states for different species of Be2B and AlBeB to bring out the details of the participation of different atoms in the total phonon density of state, particularly the role played by Al atom. The first time calculated phonon properties are clearly able to bring out the significant effect of isoelectronic substitution in Be2B. 相似文献
68.
The structural, electronic, vibrational and thermodynamical properties of transition metal carbides RuC, RhC, PdC and AgC are investigated using the plane-wave pseudopotentials method within the generalized gradient approximation (GGA) in the frame of density functional theory (DFT). There is a good agreement between present theoretical and available experimental theoretical data in the case of ground state properties such as lattice parameter and bulk modulus. The electronic band structure of these compounds show that all compounds except RuC in zinc blende phase are metallic in nature. RuC in zinc blende phase is semiconducting in nature with an indirect band gap. The phonon properties of RhC, PdC and AgC are investigated for the first time. The phonon frequencies in the phonon dispersion curves are positive throughout the Brillouin zone for zinc blende RuC and AgC and rocksalt RhC and PdC indicating dynamical stability for these compounds in the said phases. Temperature variation of thermodynamical properties for noble metal carbides are calculated and discussed. 相似文献
69.
70.
Vikram Jha 《Designs, Codes and Cryptography》2014,72(3):675-686
To each non-square integer \(2^{2N+1}\ge 2^5\) there correspond semifields \(D\) of order of \(2^{2N+1}\) that contain \(\text{ GF}(4)\) . Hence there exist affine planes for each non-square order \(2^{2N+1}\ge 2^{5}\) that contain subaffine planes of order \(2^2\) . Moreover, there also exists semifields \(D_1\) and \(D_2\) , with \(|D_1|= |D_2| =|D|\) such that \(D_1\) is commutative and \(D_2\) is non-commutative but neither \(D_1\) nor \(D_2\) contains \(\text{ GF}(4)\) . 相似文献