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941.
942.
Raghvendra S. Yadav Ranu K. Dutta Manvendra Kumar Avinash C. Pandey 《Journal of luminescence》2009,129(9):1078-1082
Nano-size YBO3:Eu3+ phosphor has been synthesized by the co-precipitation method. X-ray diffraction (XRD) pattern confirmed the formation of hexagonal vaterite-type structures of YBO3:Eu3+ nanoparticles. The transmission electron microscopy (TEM) study revealed the formation of spherical YBO3:Eu3+ nanoparticles with size 20-40 nm. The photoluminescence spectra revealed that the ratio of the red emission (5D0-7F2) to the orange emission (5D0-7F1) was much higher in the synthesized nano-size YBO3:Eu3+ phosphor. The improved relative intensity, i.e., higher R/O value of emission peaks, is due to a lower symmetry of crystal field around Eu3+ ions. 相似文献
943.
In this paper we consider central limit theorems for various macroscopic observables in the high temperature region of the
Sherrington-Kirkpatrick spin glass model. With a particular focus on obtaining a quenched central limit theorem for the energy
density of the system with non-zero external field, we show how to combine the mean field cavity method with Stein’s method
in the quenched regime. The result for the energy density extends the corresponding result of Comets and Neveu in the case
of zero external field. 相似文献
944.
945.
Dependence of amplification without inversion (AWI) on the relative strength of probe and coherent field Rabi frequencies
has been studied in H2 and LiH molecules for three-level Λ configuration. We have derived exact analytical expressions for coherences and populations
keeping all the orders of probe field Rabi frequency (G) and coherent field Rabi frequency. (Θ) in the steady state limit. Previously, first-order approximation (i.e. keeping only
the first-order term in G) was used and hence AWI was studied for the condition Θ>>G. Here, by using the exact analytical expressions of coherences and populations, we have shown that AWI is maximum when Θ
is within the same order of probe field Rabi frequency G irrespective of the choice of different ro-vibrational transitions in both the molecules. However, the shape of the gain
profile and the maximum value of gain on the probe field and the absorption on coherent field depend on the choice of different
ro-vibrational levels as the upper lasing levels. Effect of bidirectional pumping, homogeneous and inhomogeneous broadening
on AWI process has been studied. By solving the density matrix equations numerically it has been shown that both the transient
and the steady state AWI can be obtained and the numerical values of coherences and populations at large time are in very
good agreement with exact analytical values in the steady state limit. It has been shown that in molecules AWI can be obtained
on probe field of smaller wavelength than that of the coherent field which has not been observed in atoms so far. 相似文献
946.
Convexifactors, Generalized Convexity, and Optimality Conditions 总被引:3,自引:0,他引:3
The recently introduced notion of a convexifactor is further studied, and quasiconvex and pseudoconvex functions are characterized in terms of convexifactors. As an application to a chain rule, a necessary optimality condition is deduced for an inequality constrained mathematical programming problem. 相似文献
947.
Inder Khosla Sourav Bhattacharya Wei-Tek Tsai 《The Journal of the Operational Research Society》1996,47(5):626-639
When a job is processed in a hypercube multi-processor, it is allocated a cube of processing elements of the requisite size. There are three distinct costs involved in the hypercube scheduling problem: the cost of detecting a free cube (allocation), the cost of migrating jobs and merging the free spaces to accommodate a larger cube request (relocation) and the cost of not meeting the due date (tardiness). Traditionally, research in this area has focused on finding efficient algorithms for allocating a free cube (if any) in the hypercube system. The relocation cost has been treated as an independent cost metric. The role of scheduling has not received much attention and present subcube allocation methods assume a first-come-first-serve (FCFS) approach over the input job set.This paper considers the underlying scheduling issues in a hypercube processing system and shows how techniques other than FCFS scheduling of the incoming jobs can help in reducing the relocation cost and hence the overall subcube resource assignment cost. We discuss five simple and easily implementable dispatching heuristics, and compare their relative performance with the FCFS scheduling rule to demonstrate the advantages of scheduling in subcube allocation. 相似文献
948.
949.
950.
S. Dutta P. K. Mohapatra V. K. Manchanda A. K. Das 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(2):245-250
The work describes a procedure of preconcentration and separation of trace amounts of Pd(II) by solid phase extraction of
the metal ion by dithiooxamide groups incorporated into a matrix of polystyrene-divinylbenzene whereas the determination of
palladium has been carried out by radiotracer technique using 109Pd (T
1/2 = 13.43 hr, E
γ = 311, 647 keV). The experiments were carried out using both batch method and column operation. Parameters such as the amount
of resin, effect of pH, equilibration rate, sorption and desorption of metal ions have been studied. The maximum sorption
capacity for palladium was found to be 0.10 mmol·g−1 at pH 6.0. The method is rapid, has a good accuracy and can be used routinely. 相似文献