全文获取类型
收费全文 | 4549篇 |
免费 | 150篇 |
国内免费 | 297篇 |
专业分类
电工技术 | 106篇 |
综合类 | 183篇 |
化学工业 | 510篇 |
金属工艺 | 281篇 |
机械仪表 | 305篇 |
建筑科学 | 170篇 |
矿业工程 | 28篇 |
能源动力 | 157篇 |
轻工业 | 42篇 |
水利工程 | 9篇 |
石油天然气 | 29篇 |
武器工业 | 42篇 |
无线电 | 588篇 |
一般工业技术 | 1011篇 |
冶金工业 | 57篇 |
原子能技术 | 68篇 |
自动化技术 | 1410篇 |
出版年
2024年 | 6篇 |
2023年 | 51篇 |
2022年 | 89篇 |
2021年 | 100篇 |
2020年 | 89篇 |
2019年 | 92篇 |
2018年 | 78篇 |
2017年 | 72篇 |
2016年 | 115篇 |
2015年 | 136篇 |
2014年 | 176篇 |
2013年 | 196篇 |
2012年 | 248篇 |
2011年 | 352篇 |
2010年 | 231篇 |
2009年 | 248篇 |
2008年 | 308篇 |
2007年 | 263篇 |
2006年 | 304篇 |
2005年 | 226篇 |
2004年 | 254篇 |
2003年 | 240篇 |
2002年 | 220篇 |
2001年 | 133篇 |
2000年 | 122篇 |
1999年 | 96篇 |
1998年 | 91篇 |
1997年 | 77篇 |
1996年 | 78篇 |
1995年 | 63篇 |
1994年 | 49篇 |
1993年 | 38篇 |
1992年 | 41篇 |
1991年 | 24篇 |
1990年 | 24篇 |
1989年 | 18篇 |
1988年 | 18篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有4996条查询结果,搜索用时 15 毫秒
41.
V. P. Kiran R. G. Kumar A. K. Singh S. Gurunarayanan 《International Journal of Electronics》2013,100(5):295-302
In the present communication we have presented a detailed theoretical analysis of the performance of the sub-micron device in the presence of the discontinuity at the Si–SiO2 interface. It is assumed that due to interface discontinuity a potential develops at the edges (Source/Drain) in addition to the built-in-potential. This potential, called Edge Potential, measures directly the extent of the interface roughness. The effect of this potential is more critical in the case of short channel device where drain and source are in close proximity. Our analysis shows that the discontinuity is dominant at the edges but not in the channel. Drive current as well as saturation transconductance decreases in the presence of edge potential. These results suggest that the performance of the device degrades due to the interface roughness. Effect of interface roughness near the edges can be reduced at high gate voltage but it will result more interface roughness scattering. 相似文献
42.
本项目是基于美国TI公司TMS320F28xx系列DSP,进行的测试方法研究与实现。测试方法用于北京自动测试技术研究所自主研发的国产自测试设备(ATE)BC3192V50大规模集成电路测试系统。测试的原理是,通过TMS320F28xx系列DSP配备的SCI(Serial Communication Interface)串行通信接口,以此作为桥梁完成ATE与芯片之间的通信。同时,实现自动测试设备与测试系统的测试向量的匹配。而后,完成TMS320F28xx系列DSP的功能测试以及直流参数测试。 相似文献
43.
The power conversion efficiency of solar cells can be optimized via an efficient charge collection by electrodes. In this study, a simple linear polyethylenimine (LPEI), which is an insulating polymer, was adopted as the cathode interfacial layer of poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM)-based bulk-heterojunction organic solar cells (OSCs) with a non-inverted configuration. All photovoltaic parameters of the OSCs were significantly enhanced by depositing LPEI onto the oxygen plasma-treated P3HT:PCBM active layers. The causes of performance enhancement in OSCs were studied. Results revealed that the microstructure and morphology of the P3HT:PCBM layer were almost unaffected by the oxygen plasma treatment and the subsequent LPEI deposition. The X-ray photoelectron spectra of the specimens demonstrated that with the aid of oxygen plasma treatment, the linked LPEI molecules formed a well-aligned dipole layer on top of the P3HT:PCBM layer through the bonding of nitrogen (N) with oxygen (O). The results from quantum chemical calculations showed that the LPEI molecule with an N–O bond had a larger dipole moment at an appropriate direction than that without an N–O bond. By contrast, the LPEI molecules can form a dipole layer with a random orientation in the absence of N–O bonds. The conductive atomic force microscopy images of the specimens showed that the well-aligned dipole layer could facilitate electron transfer and could block hole transfer from the P3HT:PCBM to the cathodes. The well-aligned and augmented interface dipoles improved the charge selectivity at the cathodes and the photovoltaic performance of the devices. 相似文献
44.
Y.Y. Gomeniuk Y.V. GomeniukI.P. Tyagulskii S.I. TyagulskiiA.N. Nazarov V.S. LysenkoK. Cherkaoui S. MonaghanP.K. Hurley 《Microelectronic Engineering》2011,88(7):1342-1345
The paper presents the results of capacitance-voltage, conductance-frequency and current-voltage characterization in the wide temperature range (140-300 K) as well as results of low temperature (5-20 K) thermally stimulated currents (TSC) measurements of metal-oxide-semiconductor (MOS) structures with a high-κ LaSiOx dielectric deposited on p- and n-type Si(1 0 0) substrate. Interface states (Dit) distribution determined by several techniques show consistent result and demonstrates the adequacy of techniques used. Typical maxima of interface states density were found as 4.6 × 1011 eV−1cm−2 at 0.2 eV and 7.9 × 1011 eV−1cm−2 at 0.77 eV from the silicon valence band. The result of admittance spectroscopy showed the presence of local states in bandgap with activation energy Ea = 0.38 eV from silicon conductance band, which is in accord with interface states profile acquired by conductance method. Low-temperature TSC spectra show the presence of shallow traps at the interface with activation energies ranging from 15 to 32 meV. The charge carrier transport through the dielectric film was found to occur via Poole-Frenkel mechanism at forward bias. 相似文献
45.
带FPGA的PCI接口应用 总被引:1,自引:1,他引:1
文章介绍了一种带FPGA的PCI接口的应用及设计方法。该方法将PCI接口和PCI用户逻辑集成在一片FPGA里,可以对整个逻辑进行仿真测试,大大缩短了开发周期,提高了系统集成度和性能。文章重点叙述了Quicklogic公司提供的32wug TARGET接口芯片QL5030的原理和结构,分析了时序设计要点,给出了典型应用的逻辑框图和注意事项。 相似文献
46.
Although wearable devices are popular in recent years, the market share of smartwatches is relatively low. The main goal of this research is to investigate the antecedents of the intention to purchase a smartwatch. This research develops a conceptual model and hypotheses based on the theory of reasoned action and perceived values from the perspectives of software, hardware, and aesthetic design. An online questionnaire was developed and distributed on popular websites to collect data, and 260 usable responses are collected from the potential users of the Apple Watch in Taiwan. The thirteen hypotheses were validated by using partial least squares (PLS) techniques. Among the antecedents of purchase intention in the model, the attitude towards using smartwatches was found to have the strongest direct effect. Among the factors of the attitude, design aesthetics have the most significant effect. The results also show that all of the factors about smartwatch attributes directly affected the related perceived values. However, social value and performance/quality value did not affect the intention. The model demonstrated relatively good explanatory power for purchase intention in the context of smartwatches. The proposed model can provide insights to smartwatch vendors to develop their new products and marketing strategies. 相似文献
47.
K.H. Chan B. BenbakhtiC. Riddet J.R. WatlingA. Asenov 《Microelectronic Engineering》2011,88(4):362-365
In this paper a drift diffusion simulation study of a 20 nm gate-length implant-free quantum well germanium p-MOSFET is presented, which covers the impact of mobility, velocity saturation and density of interface states on the transistor performance. The parasitic gate capacitance was also studied. The simulations show that the 20 nm gate-length implant-free quantum-well transistor design has good electrostatic integrity and performance potential. 相似文献
48.
49.
A series of novel D-π-A type organic dyes with different π-linker are theoretically designed and investigated for their potential applications in dye-sensitized solar cells (DSSCs). We mainly focused on the influence of the extension of π-linker on the overall efficiency. The discussions are classified into two aspects: one is the isolated dyes and the other is the dye-TiO2 system. The calculated results indicate that the isolated dyes THI-2T-C, THI-4T-3C, and THI-6T-5C have the better overall efficiency. Further, the THI-4T-3C and THI-5T-4C have the acceptable performance if the dye-TiO2 system is considered. Combination of the isolated and the adsorbed systems, the THI-4T-3C with the moderate π-linker is considered to be more suitable choice for thieno[2,3-b]indole-based dyes rather than the longest π-linker. 相似文献
50.
本文研究了UNI提供的服务,UNI信令的传输和调用方式以及UNI地址空间等关键技术。最后基于GMPLS RSVP-TE扩展实现UNI信令,给出了各个节点的有限状态机。 相似文献