全文获取类型
收费全文 | 2704篇 |
免费 | 25篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 88篇 |
综合类 | 3篇 |
化学工业 | 525篇 |
金属工艺 | 93篇 |
机械仪表 | 77篇 |
建筑科学 | 34篇 |
能源动力 | 141篇 |
轻工业 | 122篇 |
水利工程 | 11篇 |
石油天然气 | 6篇 |
无线电 | 346篇 |
一般工业技术 | 437篇 |
冶金工业 | 661篇 |
原子能技术 | 45篇 |
自动化技术 | 151篇 |
出版年
2023年 | 15篇 |
2022年 | 17篇 |
2021年 | 41篇 |
2020年 | 16篇 |
2019年 | 17篇 |
2018年 | 17篇 |
2017年 | 23篇 |
2016年 | 29篇 |
2015年 | 28篇 |
2014年 | 47篇 |
2013年 | 115篇 |
2012年 | 71篇 |
2011年 | 106篇 |
2010年 | 89篇 |
2009年 | 88篇 |
2008年 | 98篇 |
2007年 | 96篇 |
2006年 | 74篇 |
2005年 | 59篇 |
2004年 | 61篇 |
2003年 | 101篇 |
2002年 | 71篇 |
2001年 | 63篇 |
2000年 | 44篇 |
1999年 | 82篇 |
1998年 | 310篇 |
1997年 | 173篇 |
1996年 | 108篇 |
1995年 | 69篇 |
1994年 | 82篇 |
1993年 | 70篇 |
1992年 | 38篇 |
1991年 | 34篇 |
1990年 | 45篇 |
1989年 | 33篇 |
1988年 | 23篇 |
1987年 | 26篇 |
1986年 | 25篇 |
1985年 | 31篇 |
1984年 | 23篇 |
1983年 | 30篇 |
1982年 | 16篇 |
1981年 | 14篇 |
1980年 | 23篇 |
1979年 | 13篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1976年 | 21篇 |
1975年 | 10篇 |
1974年 | 10篇 |
排序方式: 共有2740条查询结果,搜索用时 0 毫秒
41.
Takauchi H. Tamura H. Matsubara S. Kibune M. Doi Y. Chiba T. Anbutsu H. Yamaguchi H. Mori T. Takatsu M. Gotoh K. Sakai T. Yamamura T. 《Solid-State Circuits, IEEE Journal of》2003,38(12):2094-2100
We describe a CMOS multichannel transceiver that transmits and receives 10 Gb/s per channel over balanced copper media. The transceiver consists of two identical 10-Gb/s modules. Each module operates off a single 1.2-V supply and has a single 5-GHz phase-locked loop to supply a reference clock to two transmitter (Tx) channels and two receiver (Rx) channels. To track the input-signal phase, the Rx channel has a clock recovery unit (CRU), which uses a phase-interpolator-based timing generator and digital loop filter. The CRU can adjust the recovered clock phase with a resolution of 1.56 ps. Two sets of two-channel transceiver units were fabricated in 0.11-/spl mu/m CMOS on a single test chip. The transceiver unit size was 1.6 mm /spl times/ 2.6 mm. The Rx sensitivity was 120-mVp-p differential with a 70-ps phase margin for a common-mode voltage ranging from 0.6 to 1.0 V. The evaluated jitter tolerance curve met the OC-192 specification. 相似文献
42.
Finding module-based gene networks with state-space models - Mining high-dimensional and short time-course gene expression data 总被引:1,自引:0,他引:1
Yamaguchi R. Yoshida R. Imoto S. Higuchi T. Miyano S. 《Signal Processing Magazine, IEEE》2007,24(1):37-46
This study explores some problems to analyze time-course gene expression data by state-space models (SSMs). One problem is regarding the methods of parameter estimation and determination of the dimension of the internal state variable. Although several methods have been applied, there are few literature studies which with to compare them. Thus, this paper gives a brief review of the existing literature that use the SSM to analyze the gene expression time-course data. Another problem is the identifiability of the model. If the parameters of SSMs are simply estimated without any constraints for parameter space, they lack identifiability. To identify a system uniquely, it requires a specific algorithm to estimate the parameters with some constraints. For that purpose, an identifiable form of SSMs and an algorithm for estimating parameters are derived. The last problem is the extraction of biological information by interpreting the estimated parameters, such as mechanism of gene regulations at the module level. For that one, this paper explores methods to extract further information using the estimated parameters, that is, reconstruction of a module network from time-course gene expression data 相似文献
43.
Koh Matsumoto Kazutada Ikenaga Jun Yamamoto Kazuki Naito Yoshiki Yano Akinori Ubukata Hiroki Tokunaga Tadanobu Arimura Katsuaki Cho Toshiya Tabuchi Akira Yamaguchi Yasuhiro Harada Yuzaburo Ban Kousuke Uchiyama 《半导体学报》2011,32(1):21-23
Growth rate has a direct impact on the productivity of nitride LED production.Atmospheric pressure growth of GaN with a growth rate as high as 10μm/h and also Al0.1Ga0.9N growth of 1μm/h by using 4 inch by 11 production scale MOVPE are described.XRD of(002) and(102) direction was 200 arcsec and 250 arcsec, respectively.Impact of the growth rate on productivity is discussed. 相似文献
44.
Yamaguchi Y. Nishimura T. Akasaka Y. Fujibayashi K. 《Electron Devices, IEEE Transactions on》1992,39(5):1179-1183
The salicide technology using rapid thermal annealing was applied to MOSFETs on thin-film SOI. Since the SOI film was limited to a thickness of less than 100 nm, the silicidation reaction between Ti and Si atoms on the SOI surface exhibited new features that depended on the initial thickness of the deposited Ti. There was an optimum thickness of as-deposited Ti on silicidation due to the restricted thickness of the Si layer. Beyond the optimum point, the region adjacent to the silicided Si layer works as a Si source to assure stoichiometric TiSi2. The subthreshold slopes and carrier mobilities were not changed by the salicide process. Junction leakage characteristics were slightly degraded; however, the change was small enough for device application. The influence on AC characteristics was well demonstrated for a high-speed CMOS ring oscillator with a gate length of 0.7 μm. The minimum delay time/stage was 46 ps/stage at 5 V. This gives 1.8 times higher speed operation than the controlled bulk CMOS ring oscillators with the same design rule 相似文献
45.
The OMDR (optical-microwave double resonance) effect in the Cs D 2 line was studied for realizing a gas-cell-type Cs atomic frequency standard. A glass cell containing Cs with buffer gases (Ar/N2=1.26, total pressure=39 torr) was placed in a TE012 mode microwave cavity at a temperature of 45°C and was pumped using a GaAs semiconductor laser frequency locked to an external interferometer tuned to the 6P3/2 (F=2,3,4)←6 S 1/2(F =3) transition. The OMDR signal appearing at the resonance to the F =4←3 hyperfine transition of the 6S1/2 state shifted with detuning of the laser frequency and with change of the laser and microwave powers. The dependence of the shift on these variables around an optimum operating condition was obtained as, ΔνMW[Hz]=-(0.31±0.02) {1+(0.44±0.15) (ΔP L/P L)} ΔνL [MHz]-10(ΔV MW/V MW) 相似文献
46.
Yamaguchi Y. Mitsumoto M. Sengoku M. Abe T. 《Geoscience and Remote Sensing, IEEE Transactions on》1992,30(1):186-189
An FM-CW radar system was applied to detect a human body buried in a very wet snowpack. This radar uses the L -band microwave frequency with a maximum output power of 100 mW, and utilizes digital signal processing techniques. Field experiments were carried out to detect and map a human body embedded at a depth of 125 cm in a natural snowpack. The radar is shown to have a potential ability to detect avalanche victims, indicating that it may become a tool for snow rescuer operations 相似文献
47.
Nambu H. Kanetani K. Idei Y. Masuda T. Higeta K. Ohayashi M. Usami M. Yamaguchi K. Kikuchi T. Ikeda T. Ohhata K. Kusunoki T. Homma N. 《Solid-State Circuits, IEEE Journal of》1995,30(4):491-499
An ultrahigh-speed 72-kb ECL-CMOS RAM macro for a 1-Mb SRAM with 0.65-ns address-access time, 0.80-ns write-pulse width, and 30.24-μm 2 memory cells has been developed using 0.3-μm BiCMOS technology. Two key techniques for achieving ultrahigh speed are an ECL decoder/driver circuit with a BiCMOS inverter and a write-pulse generator with a replica memory cell. These circuit techniques can reduce access time and write-pulse width of the 72-kb RAM macro to 71% and 58% of those of RAM macros with conventional circuits. In order to reduce crosstalk noise for CMOS memory-cell arrays driven at extremely high speeds, a twisted bit-line structure with a normally on MOS equalizer is proposed. These techniques are especially useful for realizing ultrahigh-speed, high-density SRAM's, which have been used as cache and control storages in mainframe computers 相似文献
48.
Tajiri A. Minakuchi K. Komeda K. Bessho Y. Inoue Y. Yodoshi K. Yamaguchi T. 《Electronics letters》1993,29(4):369-370
A highly reliable 200 mW AlGaAs laser diode with a fundamental transverse mode has been developed, by optimising its structure with a 0.8 mu m thick p-cladding layer, a 1200 mu m long cavity length, and a front facet coating with a low reflectivity of 2%. The maximum output power was 500 mW, and stable fundamental transverse mode operation was obtained up to 350 mW. Stable operation under 200 mW and 50 degrees C was confirmed for more than 1200 h. Optical feedback noise was below 3*10/sup -14/ Hz/sup -1/.<> 相似文献
49.
A high-speed selector module has been developed. It is constructed from a selector IC mounted in a ceramic package, a power supply unit, phase shifters, and coaxial cables. The IC was designed using LSCFL and fabricated with 0.2 mu m gate length GaAs MESFETs. The selector module operated above 25 Gbit/s. It is expected to be applied to high-speed IC measurements.<> 相似文献
50.
Yamaguchi T. Uppili S. Lee J.S. Kawamoto G.H. Dosluoglu T. Simpkins S. 《Electron Devices, IEEE Transactions on》1993,40(8):1484-1495
Process and device parameters are characterized in detail for a 30-GHz f T submicrometer double poly-Si bipolar technology using a BF2-implanted base with a rapid thermal annealing (RTA) process. Temperature ramping during the emitter poly-Si film deposition process minimizes interfacial oxide film growth. An emitter RTA process at 1050°C for 30 s is required to achieve an acceptable emitter-base junction leakage current with an emitter resistance of 6.7×10-7 Ω-cm2, while achieving an emitter junction depth of 50 nm with a base width of 82 nm. The primary transistor parameters and the tradeoffs between cutoff frequency and collector-to-emitter breakdown voltage are characterized as functions of base implant dose, pedestal collector implant dose, link-base implant dose, and epitaxial-layer thickness. Transistor geometry dependences of device characteristics are also studied. Based on the characterization results for poly-Si resistors, boron-doped p-type poly-Si resistors show significantly better performance in temperature coefficient and linearity than arsenic-doped n-type poly-Si resistors 相似文献