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排序方式: 共有9075条查询结果,搜索用时 31 毫秒
971.
X. T. Tao T. Watanabe D. C. Zou S. Shimoda H. Usui H. Sato S. Miyata 《Journal of Polymer Science.Polymer Physics》1995,33(16):2205-2210
The electric field-induced dynamic phase-matching of second harmonic generation (SHG) waveguide was demonstrated by using a main chain polyarylamine. The linear and nonlinear optical properties of this polymer are presented. The optimum phase-matching thickness was controlled by applying an electric field to the polymer waveguide. The effective phase-matching thickness variation induced by poling is about 0.025 μm that is six times larger than full width at the half-maximum (FWHM) of phase-matching thickness in conventional slab waveguide. The efficient phase-matched SHG was observed from a taperless slab wave-guide. The optical loss of poled polymer on glass substrate at 632.8 nm was 2.7 dB/cm. © 1995 John Wiley & Sons, Inc. 相似文献
972.
激光等离子体能量角分布及吸收定标律 总被引:1,自引:0,他引:1
主要研究激光平面靶等离子体发射能量角分布及吸收定标律。实验利用高斯型1.06μm激光脉冲,其能量为2~50J,脉冲宽度为0.3~2.2ns,靶面平均辐照强度为1.8×1013~1.1x10~(15)W/cm~2,光束以25°角入射。实验采用了Au、Ag、Ti、Al和C_8H_8等厚靶。用等离子体卡计测量靶面吸收的激光能量。用指数函数拟合实验数据,给出了吸收效率分别作为激光强度、脉冲宽度和靶材料原子序数的函数的定标关系式。这些关系式定性地与逆轫致吸收的理论关系式相一致。 相似文献
973.
一种改进的小波除噪方法用于含噪ICP-AES光谱的处理 总被引:3,自引:1,他引:2
提出了一种改进的小波除噪方法。它基于噪声具有频率较高和幅度较小的特点 ,先排除信号中频率较高的成分 ,再丢弃余下的系数较小的成分。对模拟的含噪电感耦合等离子体原子发射光谱 (ICP AES)的处理结果表明 ,该法能克服小波平滑和小波去噪的一些缺陷 ,可去除更多噪声 ,而信号强度不受影响。同时 ,基线变得平坦 ,有利于峰高的定量计算。用该法处理实测ICP AES光谱 ,效果满意。 相似文献
974.
Reducing the ICRH (ion cyclotron range frequency) antenna-plasma interaction is one of the key points for reaching very long tokamak discharges. One problem which limits such discharges, is the appearance of hot spots on the surface of the antenna: Radio Frequency (RF) sheaths modify the properties of the edge plasma by rectifying the RF potential along open magnetic field lines and can induce hot spots. This paper investigates the corrections to sheath potentials introduced by the interactions between adjacent flux tubes. Our theoretical study started from an oscillating double Langmuir probe model, in which a transverse influx of current was included. This model was confronted with 1D PIC simulations along a magnetic field line, and demonstrated that current exchanges can decrease mean potentials. A 2D electrostatic fluid code was then developed, which couples adjacent flux tubes in a poloidal cross section with collisional conductivity or polarization currents. It showed that transverse currents are able to smooth structures smaller than a characteristic size in the sheath potential maps (results for Tore Supra). These computed rectified potentials can be used to obtain the DC electric fields in front of the antenna. And then, it gives an estimate of the particle drift and the energy flux on the antenna structure, which can explain hot spots. 相似文献
975.
A charged sheath between a multi‐component plasma and an absorbing and conducting wall was considered analytically in the framework of a hydrodynamic model. The model accounted for the inertia and pressures of all the plasma components and both wall polarities. An existence criterion for the steady sheath with a monotonous distribution of the electric potential was derived based on analysis of the Sagdeev potential. The model was applied to some special cases of two‐and three‐component plasmas such as a plasma with macroparticles, and electro‐positive and ‐negative plasmas. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
976.
Deuterium discharges in the PSI device have been modelled using the coupled package of the B2 hydrodynamic plasma code and the Eirene Monte‐Carlo neutral code. Radial and axial plasma profiles have been calculated for different magnetic field configurations, various radial diffusion laws and for different values of the flux limiter in the parallel electron heat conduction law used in the B2 code. The results are compared with experimental findings. The axial variation of the magnetic field strength is found to have an important influence on the plasma state via the axial plasma flow which closely resembles the neutral gas streaming through a series of laval nozzles. For particular magnetic field configurations, an appropriate ansatz for the parallel electron heat conduction turns out to be a crucial point for the applicability of hydrodynamic models to linear devices like the plasma generator PSI. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
977.
978.
Thomas S. Ullrich 《Pramana》2004,62(2):465-481
QCD predicts a phase transition between hadronic matter and a quark-gluon plasma at high energy density. The relativistic
heavy ion collider (RHIC) at Brookhaven National Laboratory is a new facility dedicated to the experimental study of matter
under extreme conditions. Already the first round of experimental results at RHIC indicated that the conditions to create
a new state of matter are indeed reached in the collisions of heavy nuclei. Studies of particle spectra and their correlations
at low transverse momenta provide evidence of strong pressure gradients in the highly interacting dense medium and hint that
we observe a system in thermal equilibrium. Recent runs with high statistics allow us to explore the regime of hard-scattering
processes where the suppression of hadrons at large transverse momentum, and quenching of di-jets are observed thus providing
further evidence for extreme high density matter created in collisions at RHIC. 相似文献
979.
980.