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991.
利用密度泛函(DFT)三种交换/相关函数(B3LYP,B3PW91,B3P86)结合6—31G^**和 6-311G^**基组,计算了13个取代氯苯化合物的键离解能.结果表明B3PS6/6—311G^**方法是计算取代氯苯化合物键离解能的可信方法,研究发现C—Cl键的键离解能与所使用的基组和计算方法密切相关,取代基对C—Cl键的键离解能的影响不明显.研究了目标化合物的前线轨道能级差,并对取代氯苯化合物的热稳定性做了评估. 相似文献
992.
Arash Yavari Jerrold E. Marsden 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2009,60(4):723-738
This paper studies the principle of invariance of balance of energy and its consequences for a system of interacting particles
under groups of transformations. Balance of energy and its invariance is first examined in Euclidean space. Unlike the case
of continuous media, it is shown that conservation and balance laws do not follow from the assumption of invariance of balance of energy under time-dependent isometries of the ambient space. However,
the postulate of invariance of balance of energy under arbitrary diffeomorphisms of the ambient (Euclidean) space, does yield the correct conservation and balance laws.
These ideas are then extended to the case when the ambient space is a Riemannian manifold. Pairwise interactions in the case
of geodesically complete Riemannian ambient manifolds are defined by assuming that the interaction potential explicitly depends
on the pairwise distances of particles. Postulating balance of energy and its invariance under arbitrary time-dependent spatial
diffeomorphisms yields balance of linear momentum. It is seen that pairwise forces are directed along tangents to geodesics
at their end points. One also obtains a discrete version of the Doyle–Ericksen formula, which relates the magnitude of internal
forces to the rate of change of the interatomic energy with respect to a discrete metric that is related to the background
metric.
Dedicated to the memory of Shahram Kavianpour (1975-2007).
Jerrold E. Marsden: Research partially supported by the California Institute of Technology and NSF-ITR Grant ACI-0204932.
Arash Yavari: Research supported by the Georgia Institute of Technology. 相似文献
993.
Lijun Wang Fei Liu Xuwu Yang Xiaoyan Wang Ruiping Liu Sa Zhao Sanping Chen 《Thermochimica Acta》2009,490(1-2):43-46
Fourteen rare earth complexes with pyromellitic acid were synthesized and characterized by means of chemical and elemental analysis, and TG–DTG. The constant-volume combustion energies of complexes, ΔcU, were measured by a precise rotating-bomb calorimeter (RBC-type II). Their standard molar enthalpies of combustion, , and standard molar enthalpies of formation, , were calculated at T = 298.15 K. The relationship of and with the atomic numbers of the elements in the lanthanide series was examined. The results show that a certain amount of covalence is present in the chemical bond between rare earth cations and the ligand. 相似文献
994.
This compendium summarizes the fusion enthalpies of approximately 1000 new measurements. A group additivity method developed to estimate the total phase change entropies and enthalpies of organic solids is updated, applied to the new data and the results are compared. The uncertainties associated with the 1016 new measurements, ±18.5 J mol−1 K−1 and ±7.6 kJ mol−1 for total phase change entropies and enthalpies, respectively, are similar in magnitude to those reported previously. Experimental and estimated fusion entropies and fusion enthalpies along with references are available as supplementary material. 相似文献
995.
A study of the hydrolysis of adiponitrile (ADN) was performed in subcritical water to research the dependence on experimental
conditions. An L25(56) orthogonal array design (OAD) with six factors at five levels using statistical analysis was employed to optimize the experimental
conditions for each product in which the interactions between the variables were temporarily neglected. The six factors were
adiponitrile concentration (ADN c, wt%), temperature (T), time (t h), percentage of additives (reactant/additive, wt/wt%), additives (A), and pressure (p, MPa). The effects of these parameters were investigated using the analysis of variance (ANOVA) to determine the relationship
between experimental conditions and yield levels of different products. The results showed that (ADN c) and T had a significant influence on the yields of adipamide, adipamic acid, and adipic acid at p<0.05. Time was the statistically significant factor for the yield of 5-cyanovalermic acid at p<0.05 and (ADN c) was the significant factor for the yield of 5-cyanovaleramide at p<0.1. Finally, five supplementary experiments were conducted under optimized conditions predicted by the Taguchi method; the
results showed that the yield obtained of each product was no lower than that of the highest in the 25 experiments. Carbon
balance was calculated to demonstrate the validity of the experimental technique and the reliability of the results. Based
on the experimental results, a possible reaction mechanism was proposed. 相似文献
996.
Fernando Aguilar Fatima E.M. Alaoui Jos J. Segovia Miguel A. Villaman Eduardo A. Montero 《Fluid Phase Equilibria》2009,284(2):106-113
Experimental excess molar enthalpies of the ternary systems dibutyl ether (DBE) + 1-butanol + benzene and the corresponding binary systems at T = 298.15 K and T = 313.15 K at atmospheric pressure are reported. A quasi-isothermal flow calorimeter has been used to make the measurements. All the binary and the ternary systems show endothermic character. The experimental data for the binary and ternary systems have been fitted using the Redlich-Kister equation and the NRTL and UNIQUAC models. The values of the standard deviation indicate good agreement between the experimental results and those calculated from the equations. 相似文献
997.
关于广义蝶图的平衡指标集 总被引:2,自引:0,他引:2
In this paper, we introduce the concept of the general butterfly graph B[m, n; d] for integers m,n ≥ 3, d ≥ 1, determine its balance index set, and give the necessary and sufficient condition for balanced graph B[m, n; d] to exist. 相似文献
998.
High-order harmonic generation of CO_2 with different vibrational modes in an intense laser field 下载免费PDF全文
We apply the strong-field Lewenstein model to demonstrate the high-order harmonic generation of CO_2 with three vibrational modes(balance vibration,bending vibration,and stretching vibration) driven by an intense laser field.The results show that the intensity of harmonic spectra is sensitive to molecular vibrational modes,and the high harmonic efficiency with stretching vibrational mode is the strongest.The underlying physical mechanism of the harmonic emission can be well explained by the corresponding ionization yield and the time-frequency analysis.Finally,we demonstrate the attosecond pulse generation with different vibrational modes and an isolated attosecond pulse with a duration of about 112 as is generated. 相似文献
999.
The use of non-linear energy sink to passively control vibrations of a non-linear main structure under the effect of bi-frequency harmonic excitation is addressed here. The excitation is assumed to induce both 1:1 and 1:3 resonance, and the response of the system is studied after using the Multiple Scale/Harmonic Balance Method, applied to obtain amplitude modulation equations in the slow time scale. The efficiency of the non-linear energy sink to reduce or suppress vibrations of the main structure is finally discussed. 相似文献
1000.
This paper deals with the vibration analysis of corrugated beams under large amplitude displacements and temperature variations. The dynamic response depends on the shape, the period and the amplitude of the corrugations as well as on the temperature variations. These different parameters were taken into account using a homogenization process. We coupled the harmonic balance method and the Galerkin technique to derive a frequency amplitude equation, which includes the corrugation shape and temperature. Finally, the influence of different shapes of corrugation (sinusoidal, triangular and square) on the nonlinear vibration response of a corrugated beam was compared to results obtained for a planar beam. 相似文献