全文获取类型
收费全文 | 533篇 |
免费 | 0篇 |
国内免费 | 6篇 |
专业分类
化学 | 51篇 |
晶体学 | 52篇 |
力学 | 21篇 |
数学 | 7篇 |
物理学 | 408篇 |
出版年
2023年 | 11篇 |
2022年 | 6篇 |
2021年 | 3篇 |
2020年 | 7篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 13篇 |
2015年 | 23篇 |
2014年 | 24篇 |
2013年 | 55篇 |
2012年 | 18篇 |
2011年 | 36篇 |
2010年 | 32篇 |
2009年 | 33篇 |
2008年 | 27篇 |
2007年 | 30篇 |
2006年 | 34篇 |
2005年 | 20篇 |
2004年 | 22篇 |
2003年 | 14篇 |
2002年 | 29篇 |
2001年 | 17篇 |
2000年 | 12篇 |
1999年 | 19篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1975年 | 1篇 |
排序方式: 共有539条查询结果,搜索用时 15 毫秒
1.
Erik Woldt 《Journal of Physics and Chemistry of Solids》2002,63(4):699-704
The paper investigates whether a change from a homogeneous to an inhomogeneous dislocation distribution, assumed to be caused by a slight additional deformation, can lead to an increase of the recrystallization temperature of a deformed metal. In this case, the higher temperature would indicate a more stable deformation structure despite the increase of stored energy. The recrystallization temperature is related to the growth rate. Hence, the steady state velocity of a recrystallization front moving either parallel or vertically to the stripes of a simplified two-dimensional heterogeneous dislocation distribution of parallel sections of higher and lower dislocation densities is calculated. The results show that if a front growths through the high and low density sections in series an overall slower rate despite higher mean dislocation density is, indeed, possible. However, growing in the parallel arrangement always leads to a higher growth rate compared with the homogeneous case of slightly less stored energy. Since in a real structure the faster growth is likely to succeed, the recrystallization temperature observed will be lowered with additional deformation in accordance with experimental experience. 相似文献
2.
Summary Samples of synthetic leucite and boron-substituted leucite are investigated by infrared spectroscopy and spectrally resolved
thermoluminescence. Evidence is obtained in favour of the assumption that point defects in aluminosilicate lattices are originated
by exchanges of Si+4 and Al+3 ions lying in different cells. 相似文献
3.
We study the aggregation of oxygen dipoles well dispersed in a CaF2 crystal upon annealing at temperatures ranging from 370 to 420 K. The concentration of oxygen dipoles is monitored by measuring the intensity of the ionic thermocurrent peak as well as by absorption and luminescence spectroscopies. Results from three methods agree within experimental error and yield an activation energy of (1.2±0.1) eV for the diffusion of isolated oxygen centres in the crystal. 相似文献
4.
In this work, the electrochemical behavior of ferrocene (Fc) was investigated by cyclic voltammetry (CV) in room temperature ionic liquids (RTILs) of 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIBF4) on glass carbon (GC), edge plane pyrolytic graphite (EPPG) and multi‐walled carbon nanotube (MWCNTs)‐modified EPPG electrodes, respectively. The results demonstrated that on GC electrode, pairs of well‐defined reversible peaks were observed, while for the electrode of EPPG, the peak potential separation (ΔEp) is obviously larger than the theoretical value of 59 mV, hinting that the electrode of EPPG is distinguished from the commonly used electrode, consistent with the previous proposition that EPPG has many “defects”. To obtain an improved electrochemical response, multi‐walled carbon nanotubes (MWCNTs) were modified on the electrode of EPPG; the increased peak current and promoted peak potential separation not only proved the existence of “defects” in MWCNTs, but also supported that “creating active points” on an electrode is the main contribution of MWCNTs. Initiating the electrochemical research of Fc on the MWCNTs‐modified EPPG electrode in RTILs and verifying the presence of “defects” on both EPPG and MWCNTs using cyclic voltammograms (CVs) of Fc obtained in RTILs of EMIBF4, is the main contribution of this preliminary work. 相似文献
5.
Elena V. Frolova M. Ivanovskaya V. Sadykov G. Alikina A. Lukashevich S. Neophytides 《Progress in Solid State Chemistry》2005,33(2-4):317-325
Structural peculiarities of Ce–Zr–La–O and Ce–Zr–La–O/Ru samples in mean of catalytic properties are compared. The samples (Ce:Zr = 1:1, La = 10÷30 mol.%, Ru = 1.5 wt.%) were obtained by sol–gel method (X-samples) and co-precipitation (P-samples). It is shown that Ce0.45Zr0.45La0.1O2−δ/Ru X-samples are characterized by high thermal stability and the highest catalytic activity in partial methane oxidation reaction. According to XRD, BET, FTIR, EPR and XPS data it is concluded that the difference in the samples catalytic activity is caused by various disposition of Ru-containing phase on the support surface. The distinction in the dimension of Ru-containing particles (3D or 2D) is conditioned by structural peculiarities of Ce0.45Zr0.45La0.1O2−δ and Ce0.35Zr0.35La0.3O2−δ P- and X-samples. 相似文献
6.
Zinc oxide (ZnO) nanorod arrays made by the hydrothermal method were treated with hydrogen peroxide (H2O2) solution through two different approaches. One is to immerse ZnO nanorod sample into H2O2 solution. The other is a pre-treatment of spin-coating H2O2 solution on the seed layer before the growth of the ZnO nanorods. In the first approach, we found that the ultraviolet (UV) emission peak of the ZnO nanorod photoluminescence (PL) spectra was strongly dependent on the immersion time. In the second approach, the H2O2 solution influences not only the quality of the seed layer, but also the amount of the oxygen interstitial defects in the ZnO nanorods grown thereon. As a result, the UV emission intensity from the ZnO nanorods is enhanced almost five times. The ZnO nanorod arrays with few oxygen interstitial defects are prepared by the hydrogen peroxide treatment and expected to enable the fabrication of optoelectronic device with excellent performance. 相似文献
7.
Phase diagram of benzamide–benzoic acid system has been studied by the thaw–melt method. Linear velocities of crystallization of the components and the eutectic mixture were determined at different undercoolings. Values of the heat of fusion were obtained from DSC studies. Excess Gibbs free energy, excess enthalpy and excess entropy of mixing were calculated. In order to know the nature of interaction between the two components, FT-IR spectral analyses were done. In addition to these studies, computer simulation has been done to obtain an idea about the interaction energy and the optimized geometry of the eutectic mixture. Microstructural studies showed the formation of an irregular structure in the eutectic mixture, which changed with aging and on addition of impurities. 相似文献
8.
This paper is to investigate the growth of Nd:YVO4 (yttrium vanadate) crystal by the modified Czochralski technique with a submerged plate. Numerical studies are performed to examine melt convection and heat transfer during Nd:YVO4 growth. The attention is paid to study the effects of initial elevation of the submerged plate, crystal diameter, and melt level on melt inclusions. It is found that the increase in crystal rotation rate and crystal diameter, and the decrease in melt level will increase the axial temperature gradient at the edge and in the center of the crystal, and change the interface shape from convex to flat. The experiments are also carried out to confirm the feasibility of the proposed new technique for controlling melt inclusions in Nd:YVO4 crystal growth. 相似文献
9.
Shigeyasu Tanaka Yoshio Honda Norifumi Kameshiro Ryuta Iwasaki Nobuhiko Sawaki Takayoshi Tanji Mikio Ichihashi 《Journal of Crystal Growth》2004,260(3-4):360-365
We have investigated the morphology of the high-temperature-grown AlN nucleation layer and its role in the early stage of GaN growth, by means of transmission electron microscopy. The nitride was selectively grown on a 7-degree off-oriented (0 0 1) patterned Si substrate by metalorganic vapor phase epitaxy. AlN was deposited on the inclined unmasked (1 1 1) facet in the form of islands. The size of the islands varied along the slope, which is attributable to the diffusion of the growth species in the vapor phase. The GaN nucleation occurred at the region where rounded AlN islands formed densely. The threading dislocations were observed to generate in the GaN nucleated region. 相似文献
10.
W. J. M. J. Josquin 《辐射效应与固体损伤》2013,168(1-4):221-224
The trapping of 5 keV deuterium in ~ 165 and ~ 4000 nm thick BeO films grown by thermal oxidation on Be substrates was investigated at different temperatures using the D(3He,H)4He nuclear reaction. The ratio of implanted D to BeO molecules obtained at saturation is 0.24 to 0.34. The D migrates from its end of range location and distributes itself uniformly in the BeO film. With increasing implant temperature the BeO layer flakes from the Be substrate. The distribution of D in BeO films at high concentrations is not consistent with diffusivity measurements at low concentrations of T in BeO. 相似文献