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排序方式: 共有176条查询结果,搜索用时 265 毫秒
1.
陈荻 《南京师范大学学报》2021,(2):022-26
提出了一种基于短开路耦合器加载的宽带带通滤波电路. 该滤波电路通过在输入和输出端口之间,并连加载短路耦合微带谐振器和开路耦合微带谐振器实现5个传输极点和3个传输零点的带通选择特性. 对所提出的短开路耦合谐振器进行了奇偶模理论分析,揭示了其传输零极点形成的物理机理. 最后,对所提出的滤波电路进行了加工测试. 测试结果表明,所提出的宽带滤波电路能够在2.0~4.2 GHz频率范围内实现 3 dB 带通传输,工作相对带宽为73%,仿真和实测结果吻合较好. 相似文献
2.
《Thin solid films》2006,515(2):615-618
Silver tantalate AgTaO3 (ATO) and silver niobate AgNbO3 (ANO) films have been grown on to the LaAlO3 (001) and sapphire Al2O3 (0112, r-cut) single crystals by pulsed laser deposition technique from stoichiometric ATO and ANO targets. X-ray diffraction study revealed epitaxial quality of ATO and ANO films on the LaAlO3 (001) whereas on the sapphire r-cut substrate they are preferential (110) and (001) oriented. To characterize microwave films properties in the range from 1 to 40 GHz, coplanar line interdigital capacitors were fabricated by photolithography and lift-off technique. ANO film capacitors show superior properties: frequency dispersion was as low as 13%, voltage tunability (40 V, 200 kV/cm) was about 4.6% at 20 GHz, loss tangent ∼0.106 at 20 GHz, K-factor = tunability / tanδ from 49% @ 10 GHz to 33% at 40 GHz. 相似文献
3.
4.
采用0.5μm GaAs PHEMT工艺研制出了一种单片集成850nm光接收机前端,它包括金属-半导体-金属(MSM)光探测器和分布放大器.探测器光敏面积为50μm×50μm,电容为0.17pF,4V偏压下的暗电流小于17nA.分布放大器-3dB带宽接近20GHz,跨阻增益约46dBΩ;在50MHz~16GHz范围内,输入、输出电压驻波比均小于2;噪声系数在3.03~6.5 dB之间.光接收机前端在输入2.5和5Gb/s非归零伪随机二进制序列调制的光信号下,得到较为清晰的输出眼图. 相似文献
5.
在综述大功率AlGaN/GaN HFET性能退化实验结果的基础上,研究了器件退化与电流崩塌间的关联。分析了现有各类器件失效模型的优点和不足之处。通过沟道中强电场和热电子分布的研究,完善了热电子触发产生缺陷陷阱的器件退化模型。使用这一模型解释了实验中观察到的各类性能退化现象,指出优化设计异质结构可以有效减弱GaN HFET的性能退化。最后提出减弱器件性能退化的方法和途径。 相似文献
6.
2GS/s 6-bit 自校准快闪ADC 总被引:1,自引:1,他引:0
A single channel 2-GS/s 6-bit ADC with cascade resistive averaging and self foreground calibration is demonstrated in 0.18-μ m CMOS. The calibration method based on DAC trimming improves the linearity and dynamic performance further. The peak DNL and INL are measured as 0.34 and 0.22 LSB, respectively. The SNDR and SFDR have achieved 36.5 and 45.9 dB, respectively, with 1.22 MHz input signal and 2 GS/s. The proposed ADC, including on-chip track-and-hold amplifiers and clock buffers, consumes 570 mW from a single 1.8 V supply while operating at 2 GS/s. 相似文献
7.
《Ceramics International》2023,49(10):14957-14963
The high-performance single-phase semiconductor materials with higher ionic conductivity have drawn substantial attention in fuel cell applications. Semiconductor materials play a key role to enhance ionic conductivity subsequently promoting low temperature solid oxide fuel cell (LT-SOFC) research. Herein, we proposed a semiconductor Co doped Y2O3 (YCO) samples with different molar ratios, which may easily access the high ionic conductivity and electrochemical performances at low operating temperatures. The resulting fabricated fuel cell 10% Co doped Y2O3 (YCO-10) device exhibits high ionic conductivity of ∼0.16 S cm−1 and a feasible peak power density of 856 mW cm−2 along with 1.09 OCV at 530 °C under H2/air conditions. The electrochemical impedance spectroscopy (EIS) reveals that YCO-10 electrolyte based SOFC device delivers the least ohmic resistance of 0.11–0.16 Ω cm2 at 530-450 °C. Electrode polarization resistance of the constructed fuel cell device noticed from 0.59 Ω cm2 to 0.28 Ω cm2 in H2/air environment at different elevated temperatures (450 °C to 530 °C). This work suggests that YCO-10 can be a promising alternative electrolyte, owing to its high fuel cell performance and enhanced ionic conductivity for LT-SOFC. 相似文献
8.
《Ceramics International》2023,49(8):12214-12223
In recent years, “high-entropy” materials have attracted great attention in various fields due to their unique design concepts and crystal structures. The definition of high-entropy is also more diverse, gradually expanding from a single phase with an equal molar ratio to a multi-phase with a non-equimolar ratio. This study selected (Na0.2Bi0.2Ba0.2Sr0.2Ca0.2)TiO3 high entropy ceramics with excellent relaxation behavior. The A-site elements are divided into (x = Na, Bi, Ba) and ((1-3x)/2 = Sr, Ca) according to their inherent properties. A novel ABO3 structural energy storage ceramics (NaBaBi)x(SrCa)(1-3x)/2TiO3 (x = 0.19, 0.195, 0.2, 0.205 and 0.21) was successfully fabricated using the high entropy design concept. The ferroelectric and dielectric properties of non-equimolar ratio high-entropy ceramics were studied in detail. It was found that the dielectric constant of ∼4920 and the recoverable energy storage density of 3.86 J/cm3 (at 335 kV/cm) can be achieved simultaneously at x = 0.205. The results indicate that the design concept of high-entropy materials with a non-equal molar ratio is an effective means to achieve distinguished energy storage performance in lead-free ceramics. 相似文献
9.
Xiaojun Quan Gang Chen Ping Cheng 《International Journal of Heat and Mass Transfer》2011,54(9-10):2110-2115
Effects of imposed DC electric fields on microbubble growth generated from a rectangular Pt micro-heater (140 × 100 μm) fabricated on one wall of the microchannel under pulse heating are investigated experimentally in this paper. Bubble dynamics and surface temperature response of the microheater during pulse heating are observed and recorded using a high speed CCD and data acquisition system. Measurements of nucleation time and nucleation temperature and heat flux at boiling inception are taken at a fixed flow rate of 0.6 ml/min and pulse width of 1 ms, and with the electric field strength gradually increasing from zero. With increasing electric field strength, it is found that heat flux required for boiling inception is increased, boiling nucleation time is delayed, and nucleation temperature is reduced. Bubble growth is suppressed by the inward dielectrophoresis force acting at the vapor/water interface which is induced by the electric field. As a result, the diameter of the bubble becomes smaller, and the interface instability is suppressed during the bubble growth period. In addition, it is found that multiple nucleate sites appear on the surface of the micro-heater at high heat flux when the electric field is increased to a sufficiently high strength. A map showing regimes of single and multi nucleate sites in a plot of heat flux versus electric field strength is obtained. 相似文献
10.