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151.
140 GHz高速无线通信技术研究 总被引:3,自引:0,他引:3
太赫兹频段的宽带特性使得其在高速无线通信领域存在巨大的应用潜力,当前太赫兹通信存在的主要问题是辐射功率低、大气衰减严重及调制解调困难。该文在提出了基于肖特基二极管次谐波混频技术+16 QAM高速数字调制解调技术的太赫兹波超高速信息传输系统实现方案,该方案提高了太赫兹通信的频谱效率。并在国内首次实现了140 GHz无线通信实验系统,以实验方法验证了太赫兹信道的幅相失真特性完全满足高阶数字信号的传输要求。该系统在0.5 m距离上实现了10 Gbps无线传输实验和高清视频传输,辐射功率-3 dBm,系统误码率小于1e-6。 相似文献
152.
提出了一种简单、科学、有效的高截止频率肖特基势垒二极管设计方法。通过SMIC 180 nm工艺制备的肖特基二极管的截止频率为800 GHz,分析测试结果和仿真数据优化后的肖特基势垒二极管截止频率可以达到1 THz左右。完成了包括天线、匹配电路和肖特基势垒二极管的集成探测器,在220 GHz下其测试响应率可达130 V/W,等效噪声功率估计为400 pw/ 。完成了陶瓷瓶内不可见液面的成像实验并取得了良好的效果。 相似文献
153.
D. E. Walker Jr. M. Gao X. Chen W. J. Schaff L. J. Brillson 《Journal of Electronic Materials》2006,35(4):581-586
A new approach to studying Schottky barrier formation on a nanometer scale is demonstrated using both Auger electron spectroscopy
core level shift and secondary electron threshold work function measurements on cleaved epilayers. Band bending induced by
metallization of cleaved epilayer surfaces can be investigated without introducing defects due to chemical or ion beam surface
cleaning. For GaN epilayers, this approach also avoids complications due to piezoelectric effects on polar-axis growth surfaces.
Initial investigations of Au and Ag Schottky contact formation on GaN in ultrahigh vacuum reveal the presence of a pinning
level ∼1.7 eV above the valence band edge. 相似文献
154.
基于热电子发射和热电子场发射模式,利用I-V方法研究了Pt/Au/n-InGaN肖特基接触的势垒特性和电流输运机理,结果表明,在不同背景载流子浓度下,Pt/Au/n-InGaN肖特基势垒特性差异明显.研究发现,较低生长温度制备的InGaN中存在的高密度施主态氮空位(VN)缺陷导致背景载流子浓度增高,同时通过热电子发射模式拟合得到高背景载流子浓度的InGaN肖特基势垒高度和理想因子与热电子场发射模式下的结果差别很大,表明VN缺陷诱发了隧穿机理并降低了肖特基势垒高度,相应的隧穿电流显著增大了肖特基势垒总的输运电流,证实热电子发射和缺陷辅助的隧穿机理共同构成了肖特基势垒的电流输运机理.低背景载流子浓度的InGaN肖特基势垒在热电子发射和热电子场发射模式下拟合的结果接近一致,表明热电子发射是其主导的电流输运机理. 相似文献
155.
The Ti/Pt/Au metallization system has an advantage of resisting KOH or TMAH solution etching. To form a good ohmic contact, the Ti/Pt/Au metallization system must be alloyed at 400℃. However, the process temperatures of typical MEMS packaging technologies, such as anodic bonding, glass solder bonding and eutectic bonding, generally exceed 400℃. It is puzzling if the Ti/Pt/Au system is destroyed during the subsequent packaging process. In the present work, the resistance of doped polysilicon resistors contacted by the Ti/Pt/Au metallization system that have undergone different temperatures and time are measured. The experimental results show that the ohmic contacts will be destroyed if heated to 500℃. But if a 20 nm Pt film is sputtered on heavily doped polysilicon and alloyed at 700℃ before sputtering Ti/Pt/Au films, the Pt5Si2-Ti/Pt/Au metallization system has a higher service temperature of 500℃, which exceeds process temperatures of most typical MEMS packaging technologies. 相似文献
156.
Recently GaN-based high electron mobility transistors (HEMTs) have
revealed the superior properties of a high breakdown field and high
electron saturation velocity. Reduction of the gate leakage current
is one of the key issues to be solved for their further improvement.
This paper reports that an Al layer as thin as 3 nm was inserted
between the conventional Ni/Au Schottky contact and n-GaN epilayers,
and the Schottky behaviour of Al/Ni/Au contact was investigated
under various annealing conditions by current--voltage (I--V)
measurements. A non-linear fitting method was used to extract the
contact parameters from the I--V characteristic curves.
Experimental results indicate that reduction of the gate leakage
current by as much as four orders of magnitude was successfully
recorded by thermal annealing. And high quality Schottky contact
with a barrier height of 0.875 eV and the lowest reverse-bias
leakage current, respectively, can be obtained under 12 min
annealing at 450°C in N2 ambience. 相似文献
157.
158.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(10):803-809
Specific short contacts are important in crystal engineering. Hydrogen bonds have been particularly successful and together with halogen bonds can be useful for assembling small molecules or ions into crystals. The ionic constituents in the isomorphous 3,5‐dichloropyridinium (3,5‐diClPy) tetrahalometallates 3,5‐dichloropyridinium tetrachloridozincate(II), (C5H4Cl2N)2[ZnCl4] or (3,5‐diClPy)2ZnCl4, 3,5‐dichloropyridinium tetrabromidozincate(II), (C5H4Cl2N)2[ZnBr4] or (3,5‐diClPy)2ZnBr4, and 3,5‐dichloropyridinium tetrabromidocobaltate(II), (C5H4Cl2N)2[CoBr4] or (3,5‐diClPy)2CoBr4, arrange according to favourable electrostatic interactions. Cations are preferably surrounded by anions and vice versa ; rare cation–cation contacts are associated with an antiparallel dipole orientation. N—H…X (X = Cl and Br) hydrogen bonds and X …X halogen bonds compete as closest contacts between neighbouring residues. The former dominate in the title compounds; the four symmetrically independent pyridinium N—H groups in each compound act as donors in charge‐assisted hydrogen bonds, with halogen ligands and the tetrahedral metallate anions as acceptors. The M —X coordinative bonds in the latter are significantly longer if the halide ligand is engaged in a classical X …H—N hydrogen bond. In all three solids, triangular halogen‐bond interactions are observed. They might contribute to the stabilization of the structures, but even the shortest interhalogen contacts are only slightly shorter than the sum of the van der Waals radii. 相似文献
159.
160.
Alpha particle detector with planar double Schottky contacts directly fabricated on semi-insulating GaN:Fe template 下载免费PDF全文
Qun-Si Yang 《中国物理 B》2021,30(11):117303-117303
Alpha particle radiation detectors with planar double Schottky contacts (DSC) are directly fabricated on 5-μm-thick epitaxial semi-insulating (SI) GaN:Fe film with resistivity higher than 1×108Ω·cm. Under 10 V bias, the detector exhibits a low dark current of less than 5.0×10-11 A at room-temperature, which increases at higher temperatures. Linear behavior in the semi-log reverse current-voltage plot suggests that Poole-Frenkel emission is the dominant carrier leakage mechanism at high bias. Distinct double-peak characteristics are observed in the energy spectrum of alpha particles regardless of bias voltage. The energy resolution of the SI-GaN based detector is determined to be ~ 8.6% at the deposited energy of 1.209 MeV with a charge collection efficiency of ~ 81.7%. At a higher temperature of 90 ℃, the measured full width at half maximum (FWHM) rises to 235 keV with no shift of energy peak position, which proves that the GaN detector has potential to work stably in high temperature environment. This study provides a possible route to fabricate the low cost GaN-based alpha particle detector with reasonable performance. 相似文献