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71.
Doubly tunable sum frequency generation (SFG) spectra demonstrate that the water molecules at gold/electrolyte interface change their orientation with applied potential. At negative potentials, water molecules in the double layer align with their oxygen atom pointing to the solution. As potential became positive to be close to the potential of zero charge (PZC), the SFG signal decreased, suggesting the OH groups of the water molecule are either in random orientation or parallel to the electrode. As potential became more positive than the PZC, the SFG signal increased again with the oxygen-up orientation as same as in the negative potential region, indicating that water molecules interact with the adsorbed sulfate anions. The peak position of the SFG spectra indicates a relatively disordered state of water molecules at the gold electrode surface, in contrast to the previously observed ice-like structure of water at electrolyte/oxide interfaces. 相似文献
72.
电子被HF和HCl分子散射总截面的计算 总被引:1,自引:1,他引:0
利用光学势方法计算了能量在10eV—1000eV范围内电子被H、F和Cl原子散射的总截面,并与已有的实验结果和理论计算进行了比较;又利用可加性规则(additivityrule)计算得到了电子被HF和HCl分子散射的总截面,计算结果也与已有的实验结果和理论计算进行了比较 相似文献
73.
Infrared (IR)-induced second-harmonic generation in the chalcogenide glasses is observed. A phenomenological approach of IR picosecond non-linear optical (NLO) response in glass is developed for the middle IR spectral range (5–15 μm). The observed effect is explained within the framework of fifth-order NLO susceptibilities. A model that reproduces the basic characteristics of the experimental data, in which the optical non-linearities caused by photoinduced electron–phonon anharmonic interactions, is proposed. The role of the IR-induced phase matching conditions in the observed phenomenon is discussed. 相似文献
74.
激光激发的声表面波为材料表面缺陷的检测提供了有力的工具.针对含缺陷材料在模型边界上的复杂性,建立了基于平面应变的有限元模型并选取了相同厚度但含有不同深度的表面裂痕的单层铝板进行了对比计算,得到了声表面波经过不同深度的表面裂痕时产生的反射及透射信号波形的时域特征.进而引入了基于Wigner-Ville分布理论的时-频分析方法计算裂痕前、后散射的瞬态表面波的能量在时间-频率平面内分布的情形.结果显示:声表面波接近中心频率的某一频率成分在经过深度小于其中心波长的表面缺陷时,随着裂痕深度的增加,对应于该频率的反射系数呈现单调递增的趋势;而透射系数呈现递减的特征,这一结果可以为激光超声检测表面缺陷提供一种定量的表征手段. 相似文献
75.
Mathematical Diagnostics (MD) deals with identification problems arising in different practical areas. Some of these problems
can be described by mathematical models where it is required to identify points belonging to two or more sets of points. Most
of the existing tools provide some identification rule (a classifier) by means of which a given point is assigned (attributed)
to one of the given sets. Each classifier can be viewed as a virtual expert. If there exist several classifiers (experts),
the problem of evaluation of experts’ conclusions arises. In the paper for the case of supervised classification the method
of virtual experts (the VE-method) is described. Based on this method, a generalized VE method is proposed where each of the
classifiers can be chosen from a given family of classifiers. As a result, a new optimization problem with a discontinuous
functional is stated. Examples illustrating the proposed approach are provided.
The work of the second author was supported by the Russian Foundation for Fundamental Studies (RFFI) under Grant No 03-01-00668. 相似文献
76.
We have carried out some photon interaction measurements using 59.54 keV γ-rays from a 241Am source. These include γ attenuation studies as well as photoelectric absorption studies in various samples. The attenuation
studies have been made using leaf and wood samples, samples like sand, sugar etc., which contain particles of varying sizes
as well as pellets and aqueous solutions of rare earth compounds. In the case of the leaf and wood samples, we have used the
γ-ray attenuation technique for the determination of the water content in fresh and dried samples. The variation of the attenuation
coefficient with particle size has been investigated for sand and sugar samples. The attenuation studies as well as the photoelectric
studies in the case of rare earth elements have been carried out on samples containing such elements whose K-absorption edge
energies lie below and close to the γ-energy used. Suitable compounds of the rare earth elements have been chosen as mixture
absorbers in these investigations. A narrow beam good geometry set-up was used for the attenuation measurements. A well-shielded
scattering geometry was used for the photoelectric measurements. The mixture rule was invoked to extract the values of the
mass attenuation coefficients for the elements from those of the corresponding compounds. The results are consistent with
theoretical values derived from the XCOM package. 相似文献
77.
78.
I.IntroductionResearchesonChinesesynthesisdisclosethatonlywhenboththesegmentalandsupraseg-melltalfeaturesofthesyntheticspeecharesimilartothoseofthellaturalone,thesyntheticspeechwillsoundintelligibleandnatural[1].Amongekistingsynthetictechniques,theapproachbasedonacousticparametersca-nadustboththesegmentalandsuprasegmentalfeaturesofsyntheticunitsfiekiblyandcanbeconsideredasthemostreasonablesynthetictechniqueintheory.However,theparameterbasedsynthesizerisoverAfependentonthedevelopmentsofparamet… 相似文献
79.
Hirotaka Okamoto Tadashi Inoue Kunihiro Osaki 《Journal of Polymer Science.Polymer Physics》1995,33(3):417-424
The complex Young's modulus, E*(ω), and the complex strain-optical coefficient, O*(ω), which is the ratio of the birefringence to the strain, were measured for polyisoprene (PIP) over a frequency range of 1 ~ 130 Hz and a temperature range of 22 ~ ?100°C. The imaginary part of O*, O″, was positive at low frequencies and negative at high frequencies. The real part, O′, was always positive and showed a maximum. The complicated behavior of O* could be understood by the assumption that E* = ER* + EG* and O* = CRER* + CGEG*, where ER* and EG* were complex quantities and CR and CG were constants. The CR value, equal to the ordinary stress-optical coefficient measured in the rubbery plateau zone, was 2.0 × 10?9 Pa?1. The CG value, defined as the ratio O″/E″ in the glassy zone, was ?1.1 × 10?11 Pa?1. The EG*, which was the major component of E* in the glassy zone, showed almost the same frequency dependence as that of polystyrene and polycarbonate. The ER*, which was dominant in the rubbery zone, was described well by the bead-spring theory. The temperature dependence of the EG* was stronger than that of the ER*. This difference caused the breakdown of the thermorheological simplicity for E* and O* around the glass-to-rubber transition zone. © 1995 John Wiley & Sons, Inc. 相似文献
80.
H. Eduardo Roman 《Journal of statistical physics》1990,58(1-2):375-382
Extensive Monte Carlo simulations of theant-in-the-labyrinth problem on randomL* L* L simple cubic lattices are performed, forL up to 960 on a CRAY-YMP supercomputer. The exponentk for the rms displacementr witht inrt
k
is found to bek=0.190±0.003. As a second approach, large percolation clusters with chemical shells up to 300 are generated on a simple cubic lattice at criticality. The diffusion equation is then solved by using the exact enumeration technique. The corresponding critical exponentd
w
is found to be 1/d
w
=0.250±0.003.On leave from I. Institut für Theoretische für Physik, Universität Hamburg, D-2000 Hamburg, Federal Republic of Germany. 相似文献