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71.
72.
73.
[reaction: see text] A novel method for the immobilization of nucleotides has been developed. The strategy employs a highly reactive pyrrolidinium phosphoramidate zwitterion intermediate that undergoes nucleophilic attack by long-chain alkylamine-controlled pore glass (LCAA-CPG) to generate an immobilized nucleotide. Quantification of nucleotide loading was accomplished by acidic hydrolysis of the P-N bond and subsequent HPLC analysis of TMP in the presence of an internal standard. Typical nucleotide loadings of 51-59 micromol/g of support were observed. 相似文献
74.
Logarithmic Convexity for Supremum Norms of Harmonic Functions 总被引:1,自引:0,他引:1
We prove the following convexity property for supremum normsof harmonic functions. Let be a domain in Rn, 0 and E a subdomainand a compact sebset of ,respectively. Then there exists a constant = (E, 0, ) (0, 1) such that for all harmonic functions u on, the inequality
is valid.The case of concentric balls E plays a key role in the proof.For positive harmonic funcitons ono osuch balls, we determinethe sharp constant in the inequlity. 相似文献
75.
Chiral bicyclic lactam 13 was converted to the natural product (-)-argemonine 9 in six steps. This novel route to argemonine represents a general strategy for the preparation of chiral 1,3-disubstituted tetrahydroisoquinolines. 相似文献
76.
77.
P. D. Robinson Y. Hou C. Y. Meyers 《Acta Crystallographica. Section C, Structural Chemistry》1999,55(11):IUC9900147-IUC9900147
78.
According to the classical hypoelasticity theory, the hypoelasticity tensor, i.e. the fourth order Eulerian constitutive tensor,
characterizing the linear relationship between the stretching and an objective stress rate, is dependent on the current stress
and must be isotropic. Although the classical hypoelasticity in this sense includes as a particular case the isotropic elasticity,
it fails to incorporate any given type of anisotropic elasticity. This implies that one can formulate the isotropic elasticity
as an integrable-exactly classical hypoelastic relation, whereas one can in no way do the same for any given type of anisotropic
elasticity. A generalization of classical theory is available, which assumes that the material time derivative of the rotated
stress is dependent on the rotated Cauchy stress, the rotated stretching and a Lagrangean spin, linear and of the first degree
in the latter two. As compared with the original idea of classical hypoelasticity, perhaps the just-mentioned generalization
might be somewhat drastic. In this article, we show that, merely replacing the isotropy property of the aforementioned stress-dependent
hypoelasticity tensor with the invariance property of the latter under an R-rotating material symmetry group R⋆
G
0, one may establish a natural generalization of classical theory, which includes all of elasticity. Here R is the rotation tensor in the polar decomposition of the deformation gradient and G
0 any given initial material symmetry group. In particular, the classical case is recovered whenever the material symmetry
is assumed to be isotropic. With the new generalization it is demonstrated that any two non-integrable hypoelastic relations
based on any two objective stress rates predict quite different path-dependent responses in nature and hence can in no sense
be equivalent. Thus, the non-integrable hypoelastic relations based on any given objective stress rate constitute an independent constitutive class in its own right which is disjoint with and hence distinguishes itself from any class based on another
objective stress rate. Only for elasticity, equivalent hypoelastic formulations based on different stress rates may be established.
Moreover, universal integrability conditions are derived for all kinds of objective corotational stress rates and for all
types of material symmetry. Explicit, simple, integrable-exactly hypoelastic relations based on the newly discovered logarithmic
stress rate are presented to characterize hyperelasticity with any given type of material symmetry. It is shown that, to achieve
the latter goal, the logarithmic stress rate is the only choice among all infinitely many objective corotational stress rates.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
79.
80.
We present a general study of polarization measurement in multiparticle production processes, including a definition of experimentally observable quantities, the splitting into natural- and unnatural parity exchanges and a study of their relative phase, and information concerning the quantum numbers of a packet of particles. When only one single particle is detected in the final state (inclusive reactions for instance) we prove that the usual formalism for two-body reactions is applicable. Very interesting new information on multi-particle production can be reached when it can be asserted that another particle has been emitted above or below a given plane, parallel or perpendicular to the scattering plane. 相似文献