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101.
We present the simulation results of the net charge fluctuation in Au Au collisions at /Snn=130 GeV froma dynamic model, JPCIAE, and its revisions. The simulations are done for the quark-gluon matter, the directly producedpions, the pion matter, and the hadron matter. The simulated net charge fluctuation of the quark-gluon matter is closeto the thermal model prediction for the quark-gluon gas. However, the discrepancy exists comparing the simulated netcharge fluctuation for directly produced pions and the pion matter with the thermal model prediction for pion gas andthe resonance pion gas, respectively. The net charge fluctuation of hadron matter from default JPCIAE simulations isnearly 3.5 times larger than quark-gluon matter. A discussion is given for the net charge fluctuation as an evidence ofQGP phase transition. 相似文献
102.
R. Kapsimalis D. Glasgow B. Anderson S. Landsberger 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(3):1721-1726
Delayed neutron activation analysis (DNAA) remains one of the most sensitive methods of nondestructively determining fissile materials in a variety of sample matrices, provided that the samples contain only a single fissile component. This has historically been the limiting factor in many applications of DNAA, and often chemically destructive methods of analysis have needed to be utilized for many real-world samples. This work seeks to develop a method that will allow for DNAA to be utilized on samples containing multiple fissile components. Initial efforts, presented here, show that using a multivariate linear regression model to describe the delayed neutron emission profile of an irradiated sample allows for the concurrent determination of fissile nuclides in samples containing both 235U and 239Pu, without chemical separations and using only a single counting step. 相似文献
103.
The stability of Runge-Kutta methods for systems of delay differentialequations (DDEs) with multiple delays is considered. The stabilityregions of explicit and implicit Runge-Kutta methods are discussedwhen they are applied to asymptotically stable linear DDEs withmultiple delays. A simple estimate on the stability regionsof explicit Runge-Kutta methods is presented. It is shown thatthe stable step-size for numerical integration of DDEs withmultiple delays can be easily selected by means of the estimate. 相似文献
104.
105.
106.
过渡金属类立方烷原子簇化合物电子结构和二阶非线性光学性质的密度泛函理论研究 总被引:2,自引:0,他引:2
采用基于第一原理的含时密度泛函理论(TDDFT)对一系列具有类立方烷簇芯结构的过渡金属簇合物二阶非线性光学性质进行了研究。结果证明, 由于簇芯结构的对称性的影响, 这一类簇分子的二阶非线性光学系数的数值要小于三核欠完整类立方烷体系。通过对电子结构的分析, 发现二阶非线性光学性质主要是由簇芯内电荷的迁移造成的。轨道分析显示, -S原子对于电荷的迁移起主要的传递作用。定域化轨道分析证明簇分子中存在的多中心键有利于簇芯内电荷的迁移。分子模拟的研究表明:虽然类立方烷结构簇分子的值比较小, 但是通过合理的配体设计, 获得具有较大值非线性光学晶体是可能的。 相似文献
107.
Robert Grone Charles R. Johnson SA Eduardo Henry Wolkowicz 《Linear and Multilinear Algebra》1986,19(4):389-393
As a step toward understanding the unsolved problem of determining how large the permanent of a positive semi-definite matrix can be, given the eigenvalues, we note that a necessary condition for A to be a permanent maximizing matrix is that A commute with its permanental adjoint. 相似文献
108.
一水甲酸锂晶体二阶非线性光学系数的理论计算 总被引:2,自引:0,他引:2
采用有限场方法和含时耦合微扰方法,在6-31+G*基组水平上并考虑了电子相关效应和色散效应的影响,计算了一水甲酸锂晶体的宏观二阶非线性光学极化率和二阶非线性光学系数。其中非线性光学系数d31和d32与Roberts报道的相符,而另一个系数d33则比文献值大。计算结果还表明,在非共振情况下,电子相关效应对非线性光学极化率的影响远远超过了色散效应,同时表明Roberts报道的非线性光学系数比Singh等人报道的更为合理。 相似文献
109.
E. A. Jerde D. C. Glasgow J. B. Hastings 《Journal of Radioanalytical and Nuclear Chemistry》1999,242(2):473-485
A preliminary test of a liquid mercury target for the production of neutrons by spallation was undertaken at the Alternating
Gradient Synchrotron facility at Brookhaven National Laboratory. Neutron activation of elemental foils placed on the target
demonstrates that a range of neutron energies does exist, as expected, and that the neutron flux is at a maximum 10–20 cm
from the front of the target, moving deeper with increasing proton energy. Uncertainties in the activity calculations are
in general significantly <10%. Impurities in some of the foils are a significant source of interference for some reactions,
although there is no interference for most of the reactions. The presence of many interference-free reactions, along with
the low uncertainties indicates that the foils will be useful benchmarks to validate the neutronics codes utilized in the
target design. 相似文献
110.
A.R. Glasgow G.S. Ross A.T. Horton D. Enagonio H.D. Dixon C.P. Saylor G.T. Furukawa M.L. Reilly Jeanette M. Henning 《Analytica chimica acta》1957
Workers at the National Bureau of Standards and elsewhere have been conscious of the discordant results sometimes yielded by two methods for determining purity employing the same physical principle. A comparison was made on samples of benzene by the thermometeric method, by which a stirred sample is frozen at nearly constant rate, and by the calorimetric method, by which a frozen sample is melted in stages by the addition of accurately controlled increments of energy under adiabatic conditions.Benzene, purified by single crystal formation and of very high purity, was contaminated in known amounts by n-heptane and samples of the same level of purity determined by both procedures. Great care was taken to submit samples of the same composition to the different groups employing the two different methods. Further, the actual degree of contamination of the benzene was unknown to both groups until final values of the purity were submitted. Results of this comparison showed that the large divergence between the two methods that had characterized earlier comparisons is not displayed. The differences between the analyses on all three samples are roughly of the order of the statistically estimated uncertainties of the averages and less than deviations between individual experiments by one method. Comparison of the methods with absolute values of purity could not be made because of contamination of the highly purified sample of benzene with supposedly chemically adsorbed water from the borosilicate glass walls. 相似文献