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51.
A phase conjugator which includes two coherent beams that are incident upon one of a-faces of a BaTiO3:Ce crystal without internal reflection is performed experimentally. Based on the four-wave mixing, the mechanism of this conjugator is investigated numerically. In comparison with the corresponding self-pumped phase conjugator, the phase-conjugate behavior of this conjugator is established much more quickly, its phase conjugate reflectivity is greater in some cases and the intensity threshold is lower by over two orders of magnitude. The configuration of this conjugator is easy to perform because the output response exists over a wide range of angular and lateral positions of the two incident beams on the crystal. 相似文献
52.
The binary alloy/ferromagnetic metal heterostructure has drawn extensive attention in the research field of spin–orbittorque(SOT)due to the potential enhancement of SOT efficiency via composition engineering.In this work,the magneticproperties and SOT efficiency in the Pt100?xNix/Ni78Fe22 bilayers were investigated via the spin-torque ferromagneticresonance(ST-FMR)technique.The effective magnetic anisotropy field and effective damping constant extracted by analyzing the ST-FMR spectra show a weak dependence on the Ni concentration.The effective spin-mixing conductanceof 8.40×1014??1·m?2and the interfacial spin transparency Tin of 0.59 were obtained for the sample of Pt70Ni30/NiFebilayer.More interestingly,the SOT efficiency that is carefully extracted from the angular dependence of ST-FMR spectrashows a nonmonotonic dependence on the Ni concentration,which reaches the maximum at x=18.The enhancement ofthe SOT efficiency by alloying the Ni with Pt shows potential in lowering the critical switching current.Moreover,alloyingrelatively cheaper Ni with Pt may promote to reduce the cost of SOT devices. 相似文献
53.
A simplified optimal control method is presented for controlling or suppressing homoclinic bifurcations of general nonlinear oscillators with one degree-of-freedom. The simplification is based on the addition of an adjustable parameter and a superharmonic excitation in the force term. By solving an optimization problem for the optimal amplitude coefficients of the harmonic and superharmonic excitations to be used as the controlled parameters, the force term as the controller can be designed. By doing so, the control gain and small optimal amplitude coefficients can be obtained at lowest cost. As the adjustable parameter decreases, a gain of some amplitude coefficient ratio is increased to the highest degree, which means that the region where homoclinic intersection does not occur will be enlarged as much as possible, leading to the best possible control performance. Finally, it is shown that the theoretical analysis is in agreement with the numerical simulations on several concerned issues including the identification of the stable and unstable manifolds and the basins of attraction. 相似文献
54.
Cigarette smoking can damage DNA and induce spontaneous mutagenesis or carcinogenesis. Here, we describe a novel strategy for in situ monitoring of cigarette smoke-induced DNA oxidation damage and offer a method for screening natural compounds that protect DNA against tobacco smoke. The present protocol takes advantage of a fast and simple magnetic separation/mixing method and a highly sensitive chemiluminescence (CL) ELISA. The DNA immobilized on the magnetic beads was oxidized by the smoke in the absence or presence of natural compounds, and then oxidative DNA was conveniently held by magnetic force, whereas the complex tobacco smoke matrix and any remaining compounds were completely eliminated by extensive washing, and possible interferences were thus removed and oxidative damage was then sensitively monitored by CL ELISA. A library of 32 natural products was then screened and three were found to protect DNA from oxidative damage and thus may be promising compounds for the development of new drugs. Moreover, the protection effect of these three natural compounds against DNA oxidation damage was successfully classified by directly spiking them in the reference cigarettes. In addition, the potential to screen a mixture in a complex sample matrix, such as crude extracts, was also demonstrated, and hence the proposed technique can screen compounds within a complex matrix and enhance the screening throughput. 相似文献
55.
Hongjun Yan 《Mathematics and Financial Economics》2011,4(2):135-159
News about an individual stock normally has only a trivial impact on the aggregate economy. The news of the aggregate stock
market, however, may have a significant impact on the prospects of the economy, and so has a large impact on the pricing kernel.
This difference between the aggregate stock market and individual stocks is analyzed in a dynamic general equilibrium setting
with incomplete information. The main findings are as follows. First, consistent with existing empirical evidence, the correlation
between stock returns and earnings surprises is, on average, positive at the individual stock level and is lower or even negative at the aggregate level. Second, a stock’s return is less sensitive to its earnings surprises if the expected earnings growth
of the stock is more pro-cyclical. Third, a decrease of information quality of a stock increases its risk premium if the stock
accounts for a small fraction of the economy, but decreases its risk premium if the stock accounts for a large fraction. 相似文献
56.
The dynamics of charged dilute particles can be modeled by the two species Vlasov-Poisson-Boltzmann system when the particles
interact through collisions in the self-induced electric field. By constructing the compensating function for multi-species
particle system, the optimal time decay of global classical solutions to this system near a global Maxwellian is obtained
through a refined energy method. 相似文献
57.
Qi Wang Hongjun Ni Annette Pietzsch Franz Hennies Yongping Bao Yimin Chao 《Journal of nanoparticle research》2011,13(1):405-413
Water-dispersible silicon nanoparticles (Si-NPs) are desirable for applications in biological techniques. A simplified method
to synthesize such particles is reported here. The resulting Si-NPs are water-dispersible and luminescent. Under the excitation
of UV light, the Si-NPs emit strong red light with a peak maximum at 606 nm and a quantum yield of 6%. They are highly stable,
and remain so over several weeks. Fourier Transform Infrared (FTIR) spectroscopy shows a visible Si–CH2 scissoring vibration mode. Furthermore, the surface chemical bondings were confirmed by X-ray photoelectron spectroscopy
(XPS). In the Si2p and C1s core levels, Si–C components are observed. The diameters of the synthesized Si-NPS as measured by atomic force microscope (AFM) are approximately
5 nm. Furthermore, the nanoparticles can be taken up by cultured cells. Fluorescence images of Si-NPs within MCF-7 human breast
cancer cells show they are distributed throughout the cell tissue. 相似文献
58.
We consider a quasilinear wave equation of Kirchhoff type where ?>0 is a small parameter. Without any growth restrictions on the nonlinearity f(u), we prove the existence of a finite-dimensional global attractor on an appropriate (bounded) phase space. The key step is the estimate of the difference between the solutions of a quasilinear dissipative hyperbolic equation of Kirchhoff type and the corresponding quasilinear parabolic equation. 相似文献
?utt−(1+‖∇u‖2)Δu+ut+f(u)=g(x),
59.
综述国内外塑化剂迁移量测定和迁移模型研究进展,从创新实验测定方法和实验误差分析的角度简要评述了迁移量测定的研究成果;从数学模型的角度对微分方程模型、统计模型和计算机模拟3类重要迁移模型进行评述。最后指出,测定实验和迁移模型相结合来研究塑化剂迁移问题是未来一个值得重视的方法。 相似文献
60.