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991.
992.
本文概述了在KT-5C托卡马克上研究非线性离子伯恩斯坦波用的新型射频波功率发射系统,给出了工作频率选择和稳定、射频功率的传输调节、脉冲响应、耦合网络及其阻抗变换、移动式天线等实验结果,还给出了测量天线真空负载阻抗的一种简便方法,讨论了有关结果。 相似文献
993.
Summary Results of extensive computer simulations performed in liquid water are reported in order to clarify the main features of
dynamical density correlations in this system. Puzzling aspects, such as the anomalous sound wave propagation at finite wave
vectors, are related to the peculiar structural aspects of this hydrogen-bonded liquid. Additional features (such as the evolution
of the relevant memory functions at increasing wave vectors and the emergency of a second mode in the longitudinal current
spectra) are also discussed in some detail.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. 相似文献
994.
995.
A constitutive model for cyclic plasticity is briefly outlined. Then the model is implemented in a finite element code to predict the response of cyclic loaded structural components such as a double-edge-notched plate, a grove bar and a nozzle in spherical shell. Comparision with results from other theories and experiments shows that the results obtained by using the present model are very satisfactory.The Project Supported by National Natural Science Foundation of China. 相似文献
996.
997.
Jair Koiller Roberto Markarian Sylvie Oliffson Kamphorst Sônia Pinto de Carvalho 《Journal of statistical physics》1996,83(1-2):127-143
The elliptical billiard problem defines a two-dimensional integrable discrete dynamical system. Integrability not being a robust property, we study some static and time-dependent perturbations of this problem. For the static case, we observe the transition from integrability to chaos, on some perturbations of the ellipse. Then we study time-dependent perturbations, supposing that the boundary deforms periodically with the time, remaining always an ellipse. We investigate numerically the now four-dimensional phase space, looking mainly at the question of whether or not the velocity of a given trajectory may increase indefinitely. 相似文献
998.
《Surface and interface analysis : SIA》2005,37(9):743-748
This work documents the behaviour of the positive secondary ion yield of bulk polytetrafluoroethylene (PTFE) under dual‐beam depth profiling conditions employing 1 keV Ar+, Cs+ and SF5+. A unique chemical interaction is observed in the form of a dramatic enhancement of the positive secondary ion yield when PTFE is dual‐beam profiled with 1 keV Cs+. The distinct absence of such an enhancement is noted for comparison on two non‐fluorinated polymers, polyethylene terephthalate (PET) and polydimethylsiloxane (PDMS). The bulk PTFE was probed using 15‐keV, 69Ga+ primary ions in dual beam mode under static conditions; 1‐keV Ar+ (a non‐reactive, light, noble element), Cs+ (a heavier metallic ion known to form clusters) and SF5+ (a polyatomic species) served as the sputter ion species. The total accumulated primary ion dose was of the order of 1015 ions/cm2, which is well beyond the static limit. The enhancement of the positive secondary yield obtained when profiling with 1‐keV Cs+ far exceeds that obtained when SF5+ is employed. An explanation of this apparent reactive ion effect in PTFE is offered in terms of polarisation of C? F bonds by Cs+ in the vicinity of the implantation site thereby predisposing them to facile scission. The formation of peculiar, periodic CsxFy+ (where y = x ? 1) and CsxCyFz+ clusters that can extend to masses approaching 2000 amu are also observed. Such species may serve as useful fingerprints for fluorocarbons that can be initiated via pre‐dosing a sample with low‐energy Cs+ prior to static 15‐keV Ga+ analysis. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
999.
Jeffrey A. Gregus Matthew F. Vernon Richard A. Gottscho Geoffrey R. Scheller William S. Hobson Robert L. Opila Euijoon Yoon 《Plasma Chemistry and Plasma Processing》1993,13(3):521-537
Dry etching of compound semiconductors is becoming increasingly important as design ruler shrink for electronic devices. For photonic device applications, dry or plasma etching is used fin- device isolation, fine-line pattern transfer, and fabrication of optical quality interfaces. As has been well established for Si and W. plasma etching at reduced temperatures can provide superior critical dimension control and obviate the need for operating at high bias voltages that produce excessively energetic ion bombardment t. In this work, we explore low-temperature (–60 C to +60 C) etching of the compound semiconductors GaAs, AlGaAs, and AlAs, In addition to improving etch anisotropy, which provides critical dimension control, rye find thut processing at lower temperatures improves microuniformity and reduces loading effects. At high lemperaturcs, where larger samples are observed to etch more slowly than smaller pieces (loading effect), etching rates appear limited bv reactant transport to the wafer. In this regime, both microuniformity and macrouniformity arc poor. As the temperature is reduced, the etching rate becomes limited by surfitce processes us a residue containing the semiconductor elements, etchant gases, and residual background gases forms on the surface. hi this regime, the etch rare becomes independent of surface area and uniformity is improved. 相似文献
1000.
The polymer-solvent interaction was studied for two similar cellulose derivatives in the semi-dilute concentration range by static and dynamic light scattering. The trisubstituted 3-chlorophenyl carbamate (3Cl-CTC) and a mixed trisubstituted derivative with methyl groups (degree of methyl substituents: DS
Me = 1.6–1.7)combined with the abovementioned 3-chlorophenyl carbamate groups filling the still open positions at the cellulose backbone were synthesized, fractionated and characterized according to standard methods. Different kinds of associations, entangled clusters with a rod-like shape on one side and entanglement networks on the other side, exist in semi-dilute dioxane solutions caused by different polymer-solvent interactions. These quite different associations lead to either a liquid crystalline or a gel-like state upon increase of concentration. 相似文献