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91.
The leakage current behaviours of polycrystalline BiFeO3 thin films are investigated by using both conductive atomic force microscopy and current-voltage characteristic measurements. The local charge transport pathways are found to be located mainly at the grain boundaries of the films. The leakage current density can be tuned by changing the post-annealing temperature, the annealing time, the bias voltage and the light illumination, which can be used to improve the performances of the ferroelectric devices based on the BiFeO3 films. A possible leakage mechanism is proposed to interpret the charge transports in the polycrystalline BiFeO3 films. 相似文献
92.
93.
提出了一种新型光模块消光比补偿方法。该方法首先根据不同温度下驱动芯片上报电流的大小,结合光功率和消光比的计算公式,模拟出激光器光功率随电流及电压的变化曲线。然后根据要求调整激光器调制电流的大小,以保持消光比的稳定。该补偿方式有效地解决了光器件一致性较差的问题,可以将原来斜效率的指标适当放宽10%,从而提高了利用率和成品率,降低了模块生产成本。 相似文献
94.
Dong Ho Kim Su Jin Kim Seung Hwan Kim Tak Jeong Sung Min Hwang Tae Geun Kim 《固体物理学:研究快报》2011,5(8):274-276
The authors report upon the increased light‐output power (Pout) via a reduction in the forward voltage (Vf) for nonpolar a ‐plane GaN LEDs using Ni/Al/Ni/Au n‐type ohmic contacts. The specific contact resistivity of the Ni/Al/Ni/Au contact is found to be as low as 5.6 × 10–5 whereas that of a typical Ti/Al/Ni/Au contact is 6.8 × 10–4 Ω cm2, after annealing at 700 °C. The X‐ray photoelectron spectroscopy results show that the upward surface band bending is less pronounced for the Ni/Al contact compared to the Ti/Al contact, leading to a decrease in the effective Schottky barrier height (SBH). The Vf of the nonpolar LEDs decreases by 10% and Pout increases by 15% when the Ni/Al/Ni/Au scheme is used instead of the typical Ti/Al/Ni/Au metal scheme. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
95.
The effect of the Hall current on the magnetohydrodynamic (MHD) natural convection flow from a vertical permeable flat plate with a uniform heat flux is analyzed in the presence of a transverse magnetic field.It is assumed that the induced magnetic field is negligible compared with the imposed magnetic field.The boundary layer equations are reduced to a suitable form by employing the free variable formulation (FVF) and the stream function formulation (SFF).The parabolic equations obtained from FVF are numer... 相似文献
96.
Wear-resistant coatings were prepared on the surface of the Q235 low-carbon steel plate by HVAS with the carbonitride alloying self-shielded flux-cored wire. Detection and analysis on the microstructure and properties of the coatings were carried out by using scanning electron microscope, microhardness tester and wear tester. The forming, the wear resistance and its mechanism of the coatings were studied. The results show that the coatings have good forming, homogeneous microstructure and compact structure. The coatings have good hardness, the average microhardness value reaches 520 HV0.1, and the highest value is up to about 560 HV0.1. As a result, the coatings have good abrasive wear performance and adhesion strength. 相似文献
97.
Fuxue WangHai Lu Xiangqian XiuDunjun Chen Ping HanRong Zhang Youdou Zheng 《Applied Surface Science》2011,257(9):3948-3951
The effect of oxygen plasma treatment on the performance of GaN Schottky barrier diodes is studied. The GaN surface is intentionally exposed to oxygen plasma generated in an inductively coupled plasma etching system before Schottky metal deposition. The reverse leakage current of the treated diodes is suppressed in low bias range with enhanced diode ideality factor and series resistance. However, in high bias range the treated diodes exhibit higher reverse leakage current and corresponding lower breakdown voltage. The X-ray photoelectron spectroscopy analysis reveals the growth of a thin GaOx layer on GaN surface during oxygen plasma treatment. Under sub-bandgap light illumination, the plasma-treated diodes show larger photovoltaic response compared with that of untreated diodes, suggesting that additional defect states at GaN surface are induced by the oxygen plasma treatment. 相似文献
98.
In this paper, we show that the leakage current properties of BiFeO3 (BFO) thin films have been greatly improved by Zr-doping. In contrast, the magnetic properties of Zr-doped BFO films are affected as a weak ferromagnetism. Beyond the double-exchange interactions arising from the creation of Fe2+, we propose another simple model considering the replacement of the magnetically active Fe3+, time to time, by a non-active Zr4+, which is expected to induce a local ferromagnetic coupling rather than an antiferromagnetic one. 相似文献
99.
Synthesis of titanium nitride thin films deposited by a new shielded arc ion plating 总被引:2,自引:0,他引:2
Yanhui Zhao Guoqiang LinJinquan Xiao Wenchang LangChuang Dong Jun GongChao Sun 《Applied Surface Science》2011,257(13):5694-5697
Thin films of titanium nitride (TiN) were deposited on stainless steel substrates by a modified deposition technique, double-layered shielded arc ion plating with vicarious circular holes (DL-SAIP). The results show that the TiN film with the distance of 10 mm between the double-layered shield plates had the least droplets. The deposition rate of the films prepared with the new technique was more homogeneous than that of all the other shielded arc ion plating. The film/substrate adhesion and microhardness values of the TiN films were higher than 40 N and 18 GPa, respectively. Thus such TiN thin films can be expected in applications. 相似文献
100.