全文获取类型
收费全文 | 1166篇 |
免费 | 25篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 90篇 |
综合类 | 2篇 |
化学工业 | 555篇 |
金属工艺 | 20篇 |
机械仪表 | 23篇 |
建筑科学 | 19篇 |
矿业工程 | 1篇 |
能源动力 | 27篇 |
轻工业 | 91篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 41篇 |
一般工业技术 | 194篇 |
冶金工业 | 9篇 |
原子能技术 | 41篇 |
自动化技术 | 81篇 |
出版年
2023年 | 4篇 |
2022年 | 11篇 |
2021年 | 9篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 14篇 |
2017年 | 11篇 |
2016年 | 13篇 |
2015年 | 14篇 |
2014年 | 21篇 |
2013年 | 80篇 |
2012年 | 34篇 |
2011年 | 70篇 |
2010年 | 44篇 |
2009年 | 53篇 |
2008年 | 55篇 |
2007年 | 41篇 |
2006年 | 39篇 |
2005年 | 35篇 |
2004年 | 44篇 |
2003年 | 31篇 |
2002年 | 42篇 |
2001年 | 19篇 |
2000年 | 17篇 |
1999年 | 23篇 |
1998年 | 16篇 |
1997年 | 37篇 |
1996年 | 20篇 |
1995年 | 18篇 |
1994年 | 13篇 |
1993年 | 13篇 |
1992年 | 21篇 |
1991年 | 12篇 |
1990年 | 15篇 |
1989年 | 23篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 17篇 |
1985年 | 23篇 |
1984年 | 19篇 |
1983年 | 34篇 |
1982年 | 27篇 |
1981年 | 24篇 |
1980年 | 13篇 |
1979年 | 29篇 |
1978年 | 15篇 |
1977年 | 15篇 |
1976年 | 10篇 |
1975年 | 5篇 |
1973年 | 7篇 |
排序方式: 共有1197条查询结果,搜索用时 15 毫秒
991.
利用激光实时频谱直接观测分子结构变化 总被引:1,自引:1,他引:0
TAKAYOSHI KOBAYASHI 《光学精密工程》2011,19(2):200-212
利用脉宽小于5 fs的激光脉冲超快光谱同时研究了Ru0 (TPP)(CO)的电子弛豫和振动动力学.研究认为,由1Q(1.0)(π,π*)and1Qr(0.0)(π,π*)产生的信号按1Qr(1.0)(π,π*)→1Qr(0.0)(π,π*)→3(d,π*)→3(π,π*)和1Qr(0.0)(π,π*)→3(d,π*)→... 相似文献
992.
Masayuki Itagaki Yasunari Hatada Isao Shitanda Kunihiro Watanabe 《Electrochimica acta》2010,55(21):6255-463
Transmission line model (TLM) is often used for the analysis of porous electrode since the current distribution in the pore can be calculated. In the present paper, the TLM is applied to the impedance analysis of complicated porous electrode with fractal structure. Activated carbon is used as electrode material for electric double layer capacitor and its pore has branch structure. Considering the fractal structure of the activated carbon, we proposed new equivalent circuit with TLM for three sizes of pores: macropore, mesopore and micropore. In this model, we defined the ratio ξ of electric double layer parts in whole inner wall of the pore because the inner wall is separated to electrolyte/electrode interface and branch base parts. Calculated electrochemical impedance of blocking electrode shows the lumped constant region in low frequency range and the distributed constant region in low frequency range. General TLM yields the straight line with slope of 45° in the distributed constant region on the Nyquist plots. In the present analysis, it was found that the slope was 22.5° at ξ = 0 in the case of double-pores (macropore and mesopore) and 11.25° at ξ = 0 in the case of triple-pores (macropore, mesopore and micropore). 相似文献
993.
TOSHIHIRO KOBAYASHI 《International journal of systems science》2013,44(5):713-732
In this paper two types of input-output representations (static ones and dynamic ones) are presented for the class of distributed parameter systems generated by spectral operators. The input-output equations can be expressed using filtered values generated from the inputs and outputs. Using the input-output representations, the design problem of an adaptive control system is also investigated for systems with unknown input and output distribution functions. 相似文献
994.
TOSHIHIRO KOBAYASHI 《International journal of systems science》2013,44(2):247-259
In this paper we study questions regarding parameter identifiability for distributed parameter systems of hyperbolic type. The unknown parameters are input distribution functions. We consider the systems with continuous-time input-output data and the systems with discrete-time inputs-output data. For these systems we present the necessary and sufficient conditions for identifiability, in the case of a finite number of sensors. We investigate the relations between the continuous-time input-output systems and the discrete-time input-output systems from the viewpoint of identifiability. Moreover we give the sets of input distribution functions which are N-step identifiable, for the discrete-time input-output systems. 相似文献
995.
Xiong-chao Lin Keiko Ideta Jin Miyawaki Hiromichi Takebe Yong-gang Wang Seong-Ho Yoon Isao Mochida 《煤炭学报(英文版)》2012,18(1):80-87
Structural and compositional transitions of Datong coal ash and its CaCO3 additional effects were carefully examined at a temperature range of 300 to 1 600 °C by using XRD and solid state NMR. The
quantitative estimation of amorphous structures of ashes can be successfully obtained through the analyses of solid state
NMR spectra. Viscosity of molten ash and its changes with CaCO3 addition were also evaluated up to 1 700 °C by using a rotary type viscometer. Glasses with poor crystalline and amorphous
phase were continuously formed through the eutectic reaction of silica above fusing temperature (FT>1 500 °C) that caused
broadening and shift of 29Si and 27Al peaks in NMR results. With the additional amount of CaCO3 increasing, the peaks shifted to downfield obviously; the fraction of Si(OAl)0(OSi)4 decreased, while that of Si(OAl)1(OSi)1 at −84.3×10−6 increased apparently. These transitions indicated the destruction of large alumina-silicate framework into small segments
by the addition of Ca ion. 相似文献
996.
Keitaro Kondo Isao Murata Axel Klix Klaus Seidel Hartwig Freiesleben 《Fusion Engineering and Design》2009,84(7-11):1076-1080
In an irradiation experiment using a LiAl/Pb assembly, we found out that the neutron flux inside the assembly calculated with JENDL-3.3 underestimates an experimental value in the 10–16 MeV region by around 30% and that in the 0.5–5 MeV region by around 15%, while the calculated flux with JEFF-3.1 overestimates the measurement in the 5–10 MeV region by around 20%. In order to reveal a reason of the discrepancy, problems of the nuclear data libraries for lead were investigated. As a result, the following problems of the evaluated libraries were pointed out: the cross-sections of the (n,2n) reaction in JENDL-3.3 for lead isotopes are too large and cause a significant underestimation of the neutron flux above 10 MeV, which appeared in the analysis of the above experiment. Inelastic scattering data for 208Pb in JENDL-3.3 reproduce previous experimental double-differential cross-section data most well. However, those for the other lead isotopes have some problems and cause a large underestimation of the neutron flux from 0.5 to 5 MeV. The reason of the overestimation in the energy region of 5–10 MeV with JEFF-3.1 is still unclear. 相似文献
997.
Gagus Ketut Sunnardianto Isao Maruyama Koichi Kusakabe 《International Journal of Hydrogen Energy》2017,42(37):23691-23697
We investigated the minimum energy pathways and energy barriers of reversible reaction (V111 + H2?V221) based upon calculations using density functional theory. We find a comparable activation barrier of around 1.3 eV for both the dissociative chemisorption and desorption processes. The charge transfer rate from a reacting hydrogen atom to the graphene is around 0.18 e per hydrogen atom in the final state. A subsequent reaction path to recover the initial structure of V111 is realized by the migration of hydrogen atoms from V221 onto the graphene surface. The comparable energy barrier of 1.3 eV for both adsorption and desorption suggests that this novel storage and release concept has the potential to act as a hydrogen storage system for certain applications. 相似文献
998.
Masanori Takemoto Shinji Sakai Kazunori Wakai Isao Sumida Tomoki Kondou Takayasu Inatomi 《亚洲传热研究》2000,29(5):412-426
The cross flow between subchannels in a BWR fuel assembly has been typically analyzed using three types of mixing models, namely, pressure difference, turbulent mixing, and void drift which are expressed by time‐averaged flow parameters. However, in our previous paper, we expressed the above cross flow phenomenon simply by a fluctuating pressure model and confirmed its validity experimentally. In this present study, we examine the relationship between the fluctuating pressure difference and the cross flow rate more precisely by using a short mixing zone with no steady pressure difference. Results show that the experimental cross flow data agree well with the calculations using this model. Furthermore, we tried to express the fluctuating pressure difference by using a sinusoidal wave as a new cross flow model. This model is shown to have no dependence on frequency. We verify that the cross flow can be analyzed using only the pressure difference amplitude. © 2000 Scripta Technica, Heat Trans Asian Res, 29(5): 412–426, 2000 相似文献
999.
Microchannel emulsification for mass production of uniform fine droplets: integration of microchannel arrays on a chip 总被引:1,自引:0,他引:1
Isao Kobayashi Yoshihiro Wada Kunihiko Uemura Mitsutoshi Nakajima 《Microfluidics and nanofluidics》2010,8(2):255-262
We present a novel microchannel emulsification (MCE) system for mass-producing uniform fine droplets. A 60 × 60-mm MCE chip
made of single-crystal silicon has 14 microchannel (MC) arrays and 1.2 × 104 MCs, and each MC array consists of many parallel MCs and a terrace. A holder with two inlet through-holes and one outlet
through-hole was also developed for simply infusing each liquid and collecting emulsion products. The MCE chip was sealed
well by physically attaching it to a flat glass plate in the holder during emulsification. Uniform fine droplets of soybean
oil with an average diameter of 10 μm were reliably generated from all the MC arrays. The size of the resultant fine droplets
was almost independent of the dispersed-phase flow rate below a critical value. The continuous-phase flow rate was unimportant
for both the droplet generation and the droplet size. The MCE chip enabled mass-producing uniform fine droplets at 1.5 ml h−1 and 1.9 × 109 h−1, which could be further increased using a dispersed phase of low viscosity. 相似文献
1000.
Isao Hasegawa Yoshiaki Fujii Keiko Yamada Chieko Kariya Toshio Takayama 《应用聚合物科学杂志》1999,73(7):1321-1328
Lignin, prepared by digesting cedar with acetic acid, and tetraethoxysilane have been allowed for a sol–gel reaction in tetrahydrofuran using H2SO4 as catalyst to yield lignin–SiO2 hybrids in the bulk gel form. The solid-state 13C nuclear magnetic resonance spectra of the hybrids and products formed solely from the lignin under the acidic conditions revealed that the lignin underwent crosslinking during the sol–gel reaction. The degree of crosslinking increased with an increasing amount of H2SO4. The powdered hybrids have been heated at 1500°C in Ar for carbothermal reduction, resulting in the formation of SiC powders. The lignin-to-tetraethoxysilane mixing ratio of the starting solutions varied free carbon content in the SiC powders. In addition, the amount of carbonaceous residue formed from the lignin upon heating depended on the degree of crosslinking of the lignin. Thus, to adjust the amounts of both the lignin and H2SO4 was necessary for producing the hybrids suitable for precursors for SiC powders with high purity. Critical adjustment of the amounts led to the formation of SiC powders with a free carbon content of 0.57 wt %, implying that the lignin is a beneficial carbon source for the production of SiC powders by the hybrid route. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1321–1328, 1999 相似文献