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811.
由枝晶构成的AuPd和AgPd三维多孔泡沫薄膜在室温下分解甲酸制氢具有高催化活性。该高催化活性是由于纳米枝晶中存在大量的活性位点,如台阶、角、扭结、边缘以及合金间的电子效应。多孔泡沫膜除了具有较高的活性外,还具有其他优良的性能:在不需要有机添加剂的情况下,利用氢气泡模板法在Ti基板上可在5 min内快速沉积多孔泡沫催化剂,无需后处理便可用于催化甲酸分解制氢;通过将电沉积泡沫膜浸入或者拉出HCOOH+HCOONa溶液,可控制氢气的产生或停止;该泡沫催化剂通过去离子水清洗或者在H2SO4溶液中进行循环伏安扫描、干燥后就可活化重新使用。 相似文献
812.
The degradation of transconductance (G) of gate-modulated generation current IGD in LDD nMOSFET is investigated. The G curve shifts rightward under the single electron-injection-stress (EIS). The trapped electrons located in the gate oxide over the LDD region (QL) makes the effective drain voltage minish. Accordingly, the G peak in depletion (GMD) and that in weak inversion (GMW) decrease. It is found that Δ GMD and Δ GMW each have a linear relationship with the n-th power of stress time (tn) in dual-log coordinate: Δ GMD ∝ tn, Δ GMD ∝ tn (n=0.25). During the alternate stress, the injected holes neutralize QL induced by the previous EIS. This neutralization makes the effective VD restore to the initial value and then the IGD peak recovers completely. Yet the threshold voltage recovery is incomplete due to the trapped electron located over the channel (QC). As a result, GMW only recovers to the circa 50% of the initial value after the hole-injection-stress (HIS). Instead, GMD is almost recovered. The relevant mechanisms are given in detail. 相似文献
813.
Application of a multiregion model to the EM scattering from a rough surface with or without a target above it 下载免费PDF全文
An efficient multiregion model is introduced to calculate the electromagnetic scattering from a perfectly electrical conducting(PEC) rough surface with or without a PEC target above it.In the multiregion model,the rough surface is split into multiple regions depending on their position along the rough surface.Two intermediate regions are chosen as the dominant region.If a target is located above the rough surface,the target will also be included in the dominant region.The method of moments(MOM) is only adopted on the dominant region to ensure validity.Hence,the new model can greatly reduce the number of unknowns associated with full MOM analysis.The induced electric currents on the other regions are obtained by approximately considering the mutual coupling between different regions along the rough surface.Compared with the published hybrid method,this new model is not only suitable for EM scattering from a target above a rough surface but also applicable for just rough surfaces.Several numerical simulations are presented to show the validity and efficiency of the multiregion model. 相似文献
814.
815.
以水热法制备出的钛酸盐纳米带为原料,利用二次水热反应制备了Gd3+掺杂TiO2纳米带.采用XRD、TEM和N2吸附-脱吸等手段对样品的晶型、微观形貌及比表面积进行了表征,讨论了Gd3+掺杂浓度、二次水热温度对材料结构及性能的影响.研究结果表明,Gd3+的掺杂没有影响原有样品的晶型,样品保持了锐钛矿相,但二次水热温度过高会破坏纳米带的形状,掺杂提高了样品的光催化活性,最佳掺杂量为5.O;.以掺杂量为5.0;、二次水热温度为180°C制备出的样品为光催化剂降解甲基橙,在光照180min后,甲基橙的降解率可达68;. 相似文献
816.
空气及水汽的激光诱导击穿光谱特性实验研究 总被引:3,自引:0,他引:3
以大气颗粒物测量为目标,实验研究了作为背景的空气分子的激光诱导击穿光谱(laser induced breakdown spectrometry, LIBS),以NIST原子发射谱线数据库为参考,对其中的O,N,H等主要元素的特征谱线进行了标识。研究了CCD光谱仪实验参数对空气等离子体发射谱线的影响,得出积分延时大于7 μs时可以较好地减小空气分子所产生的干扰谱线,积分时间宽度大于仪器最小值(1. 1 ms)时对谱线信号强度影响较小等结论。还研究了水汽的激光诱导击穿光谱,分析了O,N,H等元素的发射谱线信号强度的变化,发现H的发射谱线信号强度与水汽含量之间具有很好的线性关系。这些结果对于在大气环境条件下,对大气颗粒物的识别具有重要的指导意义。 相似文献
817.
818.
Nonlinear feedback control of a novel hyperchaotic system and its circuit implementation 总被引:1,自引:0,他引:1 下载免费PDF全文
This paper reports a new hyperchaotic system by adding an
additional state variable into a three-dimensional chaotic dynamical
system. Some of its basic dynamical properties, such as the
hyperchaotic attractor, Lyapunov exponents, bifurcation diagram and
the hyperchaotic attractor evolving into periodic, quasi-periodic
dynamical behaviours by varying parameter k are studied. An effective
nonlinear feedback control method is used to suppress hyperchaos to
unstable equilibrium. Furthermore, a circuit is designed to realize
this new hyperchaotic system by electronic workbench (EWB).
Numerical simulations are presented to show these results. 相似文献
819.
820.
Application of the method of equivalent edge currents to composite scattering from the cone-cylinder above a dielectric rough sea surface 下载免费PDF全文
Compared with scattering from a rough surface only,
composite scattering from a target above a rough surface
has become so practical that it is a subject of great interest. At
present, this problem has been solved by some numerical methods
which will produce an enormous calculation amount. In order to
overcome this shortcoming, the reciprocity theorem (RT) and the
method of equivalent edge currents (MEC) are used in this paper. Due
to the advantage of RT, the difficulty in computing the secondary
scattered fields is reduced. Simultaneously, MEC, a high-frequency
method with edge diffraction considered, is used to calculate
the scattered field from the cone-cylinder target with a high
accuracy and efficiency. The backscattered field and the
polarization currents of the rough sea surface are evaluated by the
Kirchhoff approximation (KA) method and physical optics (PO) method,
respectively. The effects of the backscattering radar cross section
(RCS) and the Doppler spectrum on the size of the target and the
windspeed of the sea surface for different incident angles are
analysed in detail. 相似文献