全文获取类型
收费全文 | 4598篇 |
免费 | 59篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 205篇 |
综合类 | 2篇 |
化学工业 | 725篇 |
金属工艺 | 133篇 |
机械仪表 | 91篇 |
建筑科学 | 62篇 |
矿业工程 | 1篇 |
能源动力 | 109篇 |
轻工业 | 330篇 |
水利工程 | 15篇 |
无线电 | 557篇 |
一般工业技术 | 760篇 |
冶金工业 | 1276篇 |
原子能技术 | 101篇 |
自动化技术 | 300篇 |
出版年
2022年 | 33篇 |
2021年 | 48篇 |
2020年 | 23篇 |
2019年 | 21篇 |
2018年 | 42篇 |
2017年 | 46篇 |
2016年 | 80篇 |
2015年 | 49篇 |
2014年 | 67篇 |
2013年 | 167篇 |
2012年 | 144篇 |
2011年 | 161篇 |
2010年 | 112篇 |
2009年 | 152篇 |
2008年 | 153篇 |
2007年 | 116篇 |
2006年 | 109篇 |
2005年 | 122篇 |
2004年 | 89篇 |
2003年 | 103篇 |
2002年 | 108篇 |
2001年 | 110篇 |
2000年 | 100篇 |
1999年 | 146篇 |
1998年 | 503篇 |
1997年 | 288篇 |
1996年 | 253篇 |
1995年 | 148篇 |
1994年 | 139篇 |
1993年 | 128篇 |
1992年 | 62篇 |
1991年 | 68篇 |
1990年 | 56篇 |
1989年 | 45篇 |
1988年 | 57篇 |
1987年 | 47篇 |
1986年 | 44篇 |
1985年 | 43篇 |
1984年 | 52篇 |
1983年 | 52篇 |
1982年 | 41篇 |
1981年 | 42篇 |
1980年 | 49篇 |
1979年 | 32篇 |
1978年 | 29篇 |
1977年 | 26篇 |
1976年 | 46篇 |
1975年 | 14篇 |
1974年 | 24篇 |
1973年 | 13篇 |
排序方式: 共有4667条查询结果,搜索用时 15 毫秒
101.
102.
Takeshi Kobayashi Yuki Imade Daisuke Shishihara Kenji Homma Miki Nagao Ryota Watanabe Toshiyuki Yokoi Atsuo Yamada Ryoji Kanno Takashi Tatsumi 《Journal of power sources》2008
A high-capacity type of all solid-state battery was developed using sulfur electrode and the thio-LISICON electrolyte. New nano-composite of sulfur and acetylene black (AB) with an average particle size of 1–10 nm was fabricated by gas-phase mixing and showed a reversible capacity of 900 mAh g−1 at a current density of 0.013 mA cm−2. 相似文献
103.
Toshiaki Kitagawa Takashi NakaharaKosuke Maruyama Kunihiro KadoAkihiro Hayakawa Shoichi Kobayashi 《International Journal of Hydrogen Energy》2008
Lewis number represents the thermo-diffusive effects on laminar flames. That of hydrogen–air mixture varies extensively with the equivalence ratio due to the high molecular diffusivity of hydrogen. In this study, the influences of pressure and thermo-diffusive effects on spherically propagating premixed hydrogen–air turbulent flames were studied using a constant volume fan-stirred combustion vessel. It was noted that the ratio of the turbulent to unstretched laminar burning velocity increased with decreasing equivalence ratio and increasing mixture pressure. Turbulent burning velocity was dominated by three factors: (1) purely hydrodynamic factor, turbulence Reynolds number, (2) relative turbulence intensity to reaction speed, the ratio of turbulence intensity to unstretched laminar burning velocity, and (3) sensitivity of the flame to the stretch due to the thermo-diffusive effects, Lewis and Markstein numbers. A turbulent burning velocity correlation in terms of Reynolds and Lewis numbers is presented. 相似文献
104.
Yamada J. Miwa T. Koike H. Toyoshima H. Amanuma K. Kobayashi S. Tatsumi T. Maejima Y. Hada H. Mori H. Takahashi S. Takeuchi H. Kunio T. 《Solid-State Circuits, IEEE Journal of》2002,37(8):1073-1079
This paper describes a 128-kb FeRAM macro for smart-card microcontrollers. This macro, which was designed and fabricated using a 0.35-/spl mu/m three-metal CMOS and a Capacitor-on-Metal/Via-stacked-Plug (CMVP) process technology, is ideally suited for recent system LSIs such as smart-card microcontrollers. It has a flexible memory size ranging from 32 to 128 kb, a low consumption current of 0.3 mA, and endurance of more than 10/sup 8/ write/read cycles under a wide range of supply voltages, from 2.7 to 5.5 V. These characteristics, which are required of not only contact-type smart-card microcontrollers but also contactless-type ones, were achieved by using four newly developed circuit technologies: 1) a three-metal CMVP memory cell; 2) a voltage-regulating architecture; 3) a main/sub bitline and wordline structure; and 4) a dynamic-type offset sense amplifier. 相似文献
105.
N. Karasawa H. Kakehata K. Mishina J. Yamamoto S. Kobayashi 《Photonics Technology Letters, IEEE》2005,17(1):31-33
Using a cross-correlation frequency-resolved optical gating apparatus, the phases and amplitudes of ultrabroad-band optical pulses from a taper fiber have been measured for various input pulse peak powers. The measured waveforms have been compared with calculated waveforms using a finite-difference in the frequency domain method, in which no envelope approximations were used and the variation of the taper shape was taken into account. Excellent agreement between the measured and the calculated waveforms was obtained when the additional dispersion of a normal fiber and an objective was considered. 相似文献
106.
Localization via ultra-wideband radios: a look at positioning aspects for future sensor networks 总被引:3,自引:0,他引:3
Gezici S. Zhi Tian Giannakis G.B. Kobayashi H. Molisch A.F. Poor H.V. Sahinoglu Z. 《Signal Processing Magazine, IEEE》2005,22(4):70-84
UWB technology provides an excellent means for wireless positioning due to its high resolution capability in the time domain. Its ability to resolve multipath components makes it possible to obtain accurate location estimates without the need for complex estimation algorithms. In this article, theoretical limits for TOA estimation and TOA-based location estimation for UWB systems have been considered. Due to the complexity of the optimal schemes, suboptimal but practical alternatives have been emphasized. Performance limits for hybrid TOA/SS and TDOA/SS schemes have also been considered. Although the fundamental mechanisms for localization, including AOA-, TOA-, TDOA-, and SS-based methods, apply to all radio air interface, some positioning techniques are favored by UWB-based systems using ultrawide bandwidths. 相似文献
107.
A comparative study of DPSK and OOK WDM transmission over transoceanic distances and their performance degradations due to nonlinear phase noise 总被引:1,自引:0,他引:1
Mizuochi T. Ishida K. Kobayashi T. Abe J. Kinjo K. Motoshima K. Kasahara K. 《Lightwave Technology, Journal of》2003,21(9):1933-1943
We have compared experimentally the transmission performance of return-to-zero differential phase-shift keying (RZ-DPSK) with RZ-ON-OFF keying (OOK), nonreturn-to-zero differential phase-shift keying (NRZ-DPSK), and NRZ-OOK for 100/spl times/10-Gb/s transmission with a spectral efficiency of 0.22 b/s/Hz over transoceanic distances. The Q degradation of the RZ-DPSK after transmission over 9180 km was 3 dB greater than that of RZ-OOK. The experimental results clearly showed the major cause of degradation for DPSK is not cross-phase modulation but self-phase modulation. The calculated nonlinear phase noise, i.e., the Gordon-Mollenauer effect, agreed with the experimental results. A distributed-Raman-amplifier assisted erbium-doped-fiber-amplified transmission line acted well in reducing the nonlinear phase noise. 相似文献
108.
Naohiko Shimada Ken Saito Takafumi Miyata Hiroki Sato Satoshi Kobayashi Atsushi Maruyama 《Advanced functional materials》2018,28(17)
The huge information storage capability of DNA and its ability to self‐assemble can be harnessed to enable massively parallel computing in a small space. DNA‐based logic gates are designed that rely on DNA strand displacement reactions; however, computation is slow due to time‐consuming DNA reassembly processes and prone to failure as DNA is susceptible to degradation by nucleases and under certain solution conditions. Here, it is shown that the presence of a cationic copolymer boosts the speed of DNA logic gate operations that involve multiple and parallel strand displacement reactions. Two kinds of DNA molecular operations, one based on a translator gate and one on a seesaw gate, are successfully enhanced by the copolymer without tuning of computing conditions or DNA sequences. The copolymer markedly reduces operation times from hours to minutes. Moreover, the copolymer enhances nuclease resistance. 相似文献
109.
Hiroyuki Yamada Atsushi Tsurumaki‐Fukuchi Masaki Kobayashi Takuro Nagai Yoshikiyo Toyosaki Hiroshi Kumigashira Akihito Sawa 《Advanced functional materials》2015,25(18):2708-2714
Tunnel electroresistance in ferroelectric tunnel junctions (FTJs) has attracted considerable interest, because of a promising application to nonvolatile memories. Development of ferroelectric thin‐film devices requires atomic‐scale band‐structure engineering based on depolarization‐field effects at interfaces. By using FTJs consisting of ultrathin layers of the prototypical ferroelectric BaTiO3, it is demonstrated that the surface termination of the ferroelectric in contact with a simple‐metal electrode critically affects properties of electroresistance. BaTiO3 barrier‐layers with TiO2 or BaO terminations show opposing relationships between the polarization direction and the resistance state. The resistance‐switching ratio in the junctions can be remarkably enhanced up to 105% at room temperature, by artificially controlling the fraction of BaO termination. These results are explained in terms of the termination dependence of the depolarization field that is generated by a dead layer and imperfect charge screening. The findings on the mechanism of tunnel electroresistance should lead to performance improvements in the devices based on nanoscale ferroelectrics. 相似文献
110.
We investigated the possibility of forming a step-free quantum well structure. A step-free InAs monolayer was grown on a selectively
grown mesa by controlling surface phases with in-situ monitoring of surface photo-absorption. We selectively grew a GaAs buffer
at 800°C and cooled the sample keeping the (2×2)-like As stabilized surface. Atomic force microscopy (AFM) observation demonstrated
that fully step-free surfaces were formed on the 8 μm wide mesa. Then, a monolayer-thick InAs was formed on this step-free
surface and this InAs layer was capped by GaAs under the (2×2)-like condition. The quantum level of the step-free InAs layer
was evaluated by spatially resolved photoluminescence (μPL) measurement. Uniform PL intensity and the lack of a double layer
peak indicated the formation of a step-free InAs quantum well, which was in good agreement with AFM observation. 相似文献