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81.
聚三羟基丁酸脂和聚三羟基己酸脂的共聚物(PHBHHx)是一种具有良好强度和韧性的生物可降解高分子材料, 可作为组织工程心脏瓣膜支架的选择材料之一. 但其生物相容性尚不甚理想. 为此, 本工作利用丝素蛋白修饰改性高分子多孔支架, 以提高支架的生物相容性. 并将人体平滑肌细胞接种在该复合支架上进行体外培养, 以证实改性效果. 其中, 用3-(4,5-二甲基噻唑-2)-2,5-二苯基四氮唑溴盐(MTT)方法测试细胞生长, 评估复合支架的细胞相容性. 并用扫描电子显微镜观察细胞在支架上的生长形态. 结果显示, 丝素蛋白修饰改性后的复合支架更有利于细胞的粘附与生长, 平滑肌细胞在支架上表现出良好的生长形态. 这表明, 丝素能够改善多孔支架的生物相容性, 使PHBHHx/丝素蛋白复合物能更适宜作为组织工程心脏瓣膜的支架材料. 结果对于进一步研究细胞外间质在复合支架上的生长以及体外培养的组织重建有重要的参考意义. 相似文献
82.
本文利用CFD对短周期涡轮试验台的流量调节阀进行了优化设计,改进了流量调节阀喉部的流动状况,提高了调节阀对流量的控制能力;对流量调节阀尾部锥体的三种设计方案进行了比较,得到了最佳方案。 相似文献
83.
This tutorial article introduces the physics of spin transfer torques in magnetic devices. Our intention is that it be accessible to beginning graduate students. We provide an elementary discussion of the mechanism of spin transfer torque and review the theoretical and experimental progress in this field. This article is meant to set the stage for the articles which follow in this volume of the Journal of Magnetism and Magnetic Materials, which focus in more depth on particularly interesting aspects of spin-torque physics and highlight unanswered questions that might be productive topics for future research. 相似文献
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87.
Photoelectric properties of pure and Al doped vacuum deposited CdS films have been studied to explore the possibility of their
application in photoactivated liquid crystal light valves. The effect of heat treatment in oxygen atmosphere, rate of deposition
and the extent of Al doping, etc. on the resistivity, photo-response spectral characteristics, rise and decay time of photo-current,
etc. have been investigated. It has been found that in contrast to pure CdS films, the properties of Al-doped films significantly
depend on both the rate of deposition and the extent of Al doping. The dark resistivity in all cases was found to increase
with heat treatment in oxygen. Unlike pure CdS films, Al doped films show photo-conductivity which is enhanced by heat treatment.
Al doped films deposited at higher rates show better photo response even at lower light levels. At various light levels the
rise and decay time of Al-doped films were found to be fairly constant and lower than that for pure CdS films. All these properties
have been explained in terms of the presence of trapping levels due to doping. These trapping levels are also indicated by
TSC, optical absorption and EPR studies. 相似文献
88.
新研发的岩石高压渗透试验仪以静态伺服阀为主要控制元件,在脱离计算机控制条件下可使试样进水端水压保持不变。出水端水压采用调速阀控制,实现了高渗透压力下长时间的水-岩相互作用试验研究。在此基础上,提出了水-岩作用渗透液体不同时段各离子浓度变化的分析方法,并容易得到不同时段试样渗透性变化规律。为研究水-岩作用对岩石强度的影响,按基本相同条件,对该试样及未经长期水-岩渗流作用同一岩性试样进行了高渗压下的常规三轴试验,提出以试样临近破坏时的有效侧向应力大小进行强度分析,并按上述实际所加侧向压力大小及有效侧向压力大小,进行了常规饱水三轴压缩试验。试验得出,所研究蚀变岩在高渗压下水-岩作用结果与常温、常压条件测试结果类似,蚀变岩与库水的水化学反应微弱,对其自身岩体的渗透性及力学性质影响均较小。 相似文献
89.
P. S. Anil Kumar R. Jansen O. M. J. vant Erve R. Vlutters S. D. Kim J. C. Lodder 《Physica C: Superconductivity and its Applications》2001,350(3-4):166-170
Here we present the realization of a room temperature operating spin-valve transistor with huge magnetocurrent (MC=300%) at low fields. This spin-valve transistor employs hot-electron transport across a Ni81Fe19/Au/Co spin valve. Hot electrons are injected into the spin valve across a Si–Pt Schottky barrier. After traversing the spin valve, these hot electrons are collected using a second Schottky barrier (Si–Au), which provides energy and momentum selection. The collector current is found to be extremely sensitive to the spin-dependent scattering of hot electrons in the spin valve, and therefore on the applied magnetic field. We also illustrate the role of the collector diode characteristics in determining the magnetocurrent under collector bias. 相似文献
90.
A new technique is proposed for a shock tube driven by a freely moving piston. In a conventional free-piston-driven shock
tube, a rupture disk is employed between the compression tube and the shock generation tube. In the present method, however,
the conventional rupture disk is replaced by a newly developed fast action valve which is activated by the compressed gas
generated in the compression tube. The present method enables us to generate high Mach number shock waves of arbitrary strength
with good reproducibility. The performance of the new method is demonstrated experimentally. This also enables us to be carefree
to scattering of fragments of the rupture disk.
Received 6 June 1996 / Accepted 6 October 1996 相似文献