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841.
We derive the two-weight inequalities for the commutators of potential integral operators in the context of spaces of homogeneous
type. The conditions required of the weights involve the Orlicz bumps. As a consequence, we obtain the norm estimates for
these commutators for arbitrary weights.
Supported by the National Natural Science Foundation of China (Nos. 10771049, 60773174) and the Natural Science Foundation
of Hebei Province (08M001). 相似文献
842.
Wolfgang Quapp 《Journal of mathematical chemistry》2004,36(4):365-379
The reaction path is an important concept of theoretical chemistry. We discuss the definition with the help of the following of the reduced gradient (RGF) [see Quapp et al., Theoret. Chem. Acc. 100 (1998) 285], also named the Newton trajectory. All the important features of the potential energy surface are definable independently of the coordinate system. We demonstrate it for the Newton trajectory. We design a numerical scheme for the RGF method including the intrinsic curvilinear metric of internal coordinates. For the path following we extend the previous method to the use of a generalized singular value decomposition (SVD). An example of the HCN isomerization pathway is discussed. 相似文献
843.
T. Ritschel Ch. Zuhrt L. Zülicke P. J. Kuntz 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(1):127-141
ArnHCl+ van-der-Waals clusters for n = 1–13 are investigated
with the “minimal diatomics-in-molecules (DIM) model”
using ab-initio input data obtained from multi-reference
configuration-interaction calculations plus subsequent projection onto
valence-bond wavefunctions.
The results for the complexes with n = 1–3 are checked against
ab-initio calculations at the
coupled-cluster (CCSD) level with the same one-electron atomic basis set as
for the input data generation (aug-cc-pVTZ from Dunning).
In addition to the electronic ground state,
the first excited
state for the triatomic
complex (n = 1) is also studied.
The results
from the DIM model are shown to be in fair agreement with those from
advanced conventional ab-initio calculations, although there are
differences in detail. The comparison
justifies the extension of the DIM approach to n > 3.
Systematic analysis of the local minima of the multi-dimensional
potential-energy surfaces (PESs), carried out with the combined
method
described in part I (Monte-Carlo sampling plus subsequent steepest-descent
optimization), reveals simple building-up regularities for the most
stable structures (i.e. those corresponding to the global PES minimum)
at each n: apart from always having a nearly linear
(Ar–H–Cl)+ fragment as core, the aggregates show little
or no symmetry. Secondary local minima are also determined and their
structures interpreted.
The PESs for the low-lying excited states reveal a much more complicated
topography compared to the ArnH+ clusters allowing a variety
of photo-processes.
The energy level sequence of the first five excited electronic states
and the stability of the clusters in these states is studied
as a function of the cluster size n. 相似文献
844.
K. von Haeften K. Fink 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):121-124
We have investigated the electronic energies of the ground and excited
states of an octahedral helium
cluster by quantum chemical ab initio calculations. The excited levels
were calculated for the central atom for a set of different
inter atomic separations. Our approach yields potential energy curves which
are suited to describe a density dependence of the spectral features
as previously observed in photo excitation experiments. The potential
energy curves of the 2s and 2p states show a hump at
? caused by the strong perturbation of neighbouring atoms. The
existence of this hump explains the
experimentally observed blue shift and its dependence on the cluster
size or density, respectively.
The potential curves of the higher levels show almost constant
energies. Perturbations of these levels are small, because the overlap
between the Rydberg orbital and the orbitals of the surrounding atoms is
small. This is the case for both small R values
where the Rydberg orbital is well outside the cluster as well as
for large R where the density drastically decreases.
These findings coincide with the
un-shifted features of small clusters observed in experiments. 相似文献
845.
Q. X. Wang K. S. Yeo B. C. Khoo K. Y. Lam 《Theoretical and Computational Fluid Dynamics》2005,19(5):303-317
During the collapse of a bubble near a surface, a high-speed liquid jet often forms and subsequently impacts upon the opposite
bubble surface. The jet impact transforms the originally singly-connected bubble to a toroidal bubble, and generates circulation
in the flow around it. A toroidal bubble simulation is presented by introducing a vortex ring seeded inside the bubble torus
to account for the circulation. The velocity potential is then decomposed into the potential of the vortex ring and a remnant
potential. Because the remnant potential is continuous and satisfies the Laplace equation, it can be modelled by the boundary-integral
method, and this circumvents an explicit domain cut and associated numerical treatment. The method is applied to study the
collapse of gas bubbles in the vicinity of a rigid wall. Good agreement is found with the results of Best (J. Fluid Mech.
251 79–107, 1993), obtained by a domain cut method. Examination of the pressure impulse on the wall during jet impact indicates
that the high-speed liquid jet has a significant potential for causing damage to a surface. There appears to be an optimal
initial distance where the liquid jet is most damaging. 相似文献
846.
《Arabian Journal of Chemistry》2014,7(5):597-603
Heterocyclic compounds containing pyrazolines were reported to possess significant biological activity. Synthesis of 2-(ω-chloroacetonyl)-3-p-fluorophenyl-6-bromoquinazoline-4(3H)-ones (2), 2-(ω-hydrazinoacetonyl)-3-p-fluorophenyl-6-bromoquinazoline-4(3H)-ones (3) and 1′-[3H-3-p-fluorophenyl-4-oxo-6-bromoquinazoline-2-acetonyl]-3′-[1-o-chlorophenyl-3-methyl-5-azomethine-2-pyrazolidene]-5′-(substituted phenyl)-Δ2-pyrazolines (4a–j) have been described. Some of the new compounds were tested against bacteria (Gram –ve and Gram +ve) and fungi. 相似文献
847.
《Stochastic Processes and their Applications》2015,125(1):371-400
We consider a system of real-valued spins interacting with each other through a mean-field Hamiltonian that depends on the empirical magnetisation of the spins. The system is subjected to a stochastic dynamics where the spins perform independent Brownian motions. Using large deviation theory we show that there exists an explicitly computable crossover time from Gibbs to non-Gibbs. We give examples of immediate loss of Gibbsianness (), short-time conservation and large-time loss of Gibbsianness (), and preservation of Gibbsianness (). Depending on the potential, the system can be Gibbs or non-Gibbs at the crossover time . 相似文献
848.
The present work shows the presence of inevitable impurities in the semi-insulating GaAs domains when one is developing a single electron transistor (SET) and alters the quantization mechanism of single electron tunneling through the island. It is also indicated that these impurities decrease the amount of energy required to change the number of electrons on the island, which leads to a drastic reduction of SET quality. A theoretical model has been presented for elucidating the I–V characteristics of GaAs nano-crystals. It is found that this proposed model fits well the experimental data. 相似文献
849.
在QCISD(T)/6-311G(2df,p)//B3LYP/6-311G(d,p)水平上对自由基反应C2H3^. OH^.进行了计算,结果表明,经过缔合、多步H转移、CH3转移和离解等复杂过程,最终要得到8种产物(P1-P8),茯中产物P2(H2CCO H2)和P6(CH3CO^. H^.)是主要产物。本文得到的CH2CHOH(1或1‘),CH3CHO(2)和CH3COH(3)之间的过渡态TS1/2,TS1‘/3和TS2/3的能量顺序与Wesdemiotis等的实验推测相反,而与Smith等的计算结果一致。 相似文献
850.
A novel method for measuring the zeta potential of PDMS–electrolyte solution interface is presented in this paper. When an electrolyte solution passes the electrode coated with PDMS film, an electrical current will be induced due to the electrostatic potential difference between the PDMS–air interface and the PDMS–electrolyte solution interface. Based on this principle, the relationship between the measured electrical signal and the zeta potential of PDMS–electrolyte solution interface is experimentally investigated. The results show that the magnitude of the measured signal is linearly proportional to this potential difference. An empirical correlation between the zeta potential and the measured voltage signal was obtained. Good agreement was found when comparing the zeta potential calculated by this empirical equation with that reported in the published journal papers. The zeta potential measurement method presented in this paper is simple and accurate and can be used for measuring zeta potentials of other dielectric–electrolyte interfaces. 相似文献