全文获取类型
收费全文 | 1303篇 |
免费 | 23篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 84篇 |
综合类 | 1篇 |
化学工业 | 250篇 |
金属工艺 | 51篇 |
机械仪表 | 29篇 |
建筑科学 | 28篇 |
能源动力 | 60篇 |
轻工业 | 105篇 |
水利工程 | 3篇 |
无线电 | 187篇 |
一般工业技术 | 213篇 |
冶金工业 | 214篇 |
原子能技术 | 47篇 |
自动化技术 | 57篇 |
出版年
2022年 | 13篇 |
2021年 | 21篇 |
2020年 | 8篇 |
2019年 | 25篇 |
2018年 | 29篇 |
2017年 | 14篇 |
2016年 | 15篇 |
2015年 | 9篇 |
2014年 | 34篇 |
2013年 | 61篇 |
2012年 | 38篇 |
2011年 | 51篇 |
2010年 | 43篇 |
2009年 | 45篇 |
2008年 | 49篇 |
2007年 | 65篇 |
2006年 | 40篇 |
2005年 | 41篇 |
2004年 | 43篇 |
2003年 | 46篇 |
2002年 | 36篇 |
2001年 | 23篇 |
2000年 | 15篇 |
1999年 | 39篇 |
1998年 | 91篇 |
1997年 | 53篇 |
1996年 | 44篇 |
1995年 | 27篇 |
1994年 | 34篇 |
1993年 | 31篇 |
1992年 | 22篇 |
1991年 | 21篇 |
1990年 | 19篇 |
1989年 | 16篇 |
1988年 | 14篇 |
1987年 | 12篇 |
1986年 | 19篇 |
1985年 | 13篇 |
1984年 | 14篇 |
1983年 | 6篇 |
1982年 | 12篇 |
1981年 | 15篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1976年 | 10篇 |
1974年 | 4篇 |
1972年 | 7篇 |
1966年 | 3篇 |
排序方式: 共有1329条查询结果,搜索用时 15 毫秒
1.
Toshihiko Kujime Soong-Keun Hyun Hideo Nakajima 《Metallurgical and Materials Transactions A》2006,37(2):393-398
A lotus-type porous carbon steel with cylindrical pores was fabricated by the continuous zone melting method in a pressurized
mixture of hydrogen and helium gases. The porosity increases with increasing partial pressure of the hydrogen gas, while the
pore diameter remains almost constant, independent of the pressure. The ultimate tensile strength of the specimen with cylindrical
pores parallel to the tensile direction is lower than the estimated value, assuming that the strength is decreased in proportion
to the decrease of the cross-sectional area of the specimen, while the yield strength is higher than the estimated value.
The compressive yield strength is also higher than the estimated value. The increase in yield strength is considered to be
due to precipitation strengthening. The tensile strength is increased by quenching and tempering, while the elongation decreases.
Such mechanical properties are discussed in terms of the microstructural analysis. 相似文献
2.
S Noguchi M Sata H Suzuki K Ohba M Mizokami K Tanikawa 《Canadian Metallurgical Quarterly》1997,24(5):992-994
Chinese hamster lung fibroblast V79 cells have been widely used in studies of DNA damage and DNA repair. Since the p53 gene is involved in normal responses to DNA damage, we have analyzed the molecular genetics and functional status of p53 in V79 cells and primary Chinese hamster embryonic fibroblast (CHEF) cells. The coding product of the p53 gene in CHEF cells was 76 and 75% homologous to human and mouse p53 respectively, and was 95% homologous to the Syrian hamster cells. The V79 p53 sequence contained two point mutations located within a presumed DNA binding domain, as compared with the CHEF cells. Additional immunocytochemical and molecular studies confirmed that the p53 protein in V79 cells was mutated and nonfunctional. Our results indicate that caution should be used in interpreting studies of DNA damage, DNA repair and apoptosis in V79 cells. 相似文献
3.
A 4*4 directional coupler switch matrix is developed which uses, for the first time, the quantum confined Stark effect of InGaAlAs/InAlAs multiquantum well structures. The rearrangeable nonblocking 4*4 network with six 2*2 switches is shown to be perfectly functional with switching voltages between 5 and 6 V and crosstalk below -17 dB in all the operation states.<> 相似文献
4.
Toshihiko Hoshide Junpei Fujita 《Journal of Materials Engineering and Performance》2008,17(5):627-632
Strength of ground ceramics may be affected by residual stress as well as surface flaws induced by grinding. Strength prediction
for ground ceramics is convenient for mechanical design of ceramic components. In this article, a numerical procedure based
on fracture mechanics was proposed to estimate strength distribution of ground ceramics by considering grinding-induced residual
stress. Bending strength and residual stress of ground ceramics were measured for three grinding-conditions. By comparison
of simulated results with experimental ones, it was revealed that strength characteristics in experiments were well simulated
by using the proposed procedure. 相似文献
5.
6.
In this article, we consider a flexible beam with a rigid body, of which the bending vibration and the torsional vibration are decoupled. Therefore we need two control motors to suppress the vibrations. Each set of dynamic equations is treated in the form of an appropriate Hilbert space. A stabilizing feedback control law of each rotation motor will be established on the basis of modal analysis. A set of experiments has been carried out, and the results demonstrate the effectiveness of the dynamic model and the proposed control law. © 1994 John Wiley & Sons, Inc. 相似文献
7.
Yoshiyuki Uno Akira Okada Kensuke Uemura Purwadi Raharjo Toshihiko Furukawa Kosaku Karato 《Precision Engineering》2005,29(4):171-455
A new finishing process for metal molds by large-area electron beam (EB) irradiation is proposed in this study. In the large-area EB irradiation equipment used here, an EB with high-energy density is irradiated without focusing the beam, and so the EB with a maximum diameter of 60 mm can be used for melting or evaporating metal surface instantly. Experimental results show that the surface roughness decreases from 6 μmRz to less than 1 μmRz in just a few minutes under proper machining conditions. The corrosion resistance of metal mold surface also could be greatly improved by large-area EB irradiation. Furthermore, the surface roughness of tilting surface close to 90° could be well improved. Therefore, large-area EB irradiation method has a possibility to become a high-efficiency finishing process for metal molds. 相似文献
8.
9.
Y. Ohshima H.S. Ahn M. Aoki S. Awa M. Fukushima H. Hayashii X.Q. Hu T.W. Hur S. Igarashi H. Ikeda H.C. Jeong K. Kaneyuki D.Y. Kim S.K. Kim A. Kuzmin M.H. Lee S. Noguchi A. Ochi H. Sagawa N. Sato N. Sugiyama K. Tamai T. Tanimori N. Toomi T.J. Wang K. Watanabe Y. Watanabe X.C. Zhong Y.C. Zhu 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1996,380(3):517-523
We studied the performance of a prototype electromagnetic calorimeter for the BELLE detector at the KEK proton synchrotron for an energy range of 0.25–3.5 GeV. The prototype consisted of an array of 6 × 5 CsI(Tl) crystals with 30 cm length (16.2 radiation lengths) and about 6 cm × 6 cm cross section. The scintillation light of each CsI(Tl) crystal was read out by two large-area PIN photodiodes and charge-sensitive preamplifiers attached at the rear face of the crystal. We measured the energy and position resolution for electrons and the e/π separation for two sets of matrix configurations: one corresponded to the center and the other to the edge of the barrel calorimeter. The overall performance measured by the test proves that the prototype calorimeter is satisfactory for the use in the BELLE detector. 相似文献
10.
Noguchi K. Nagata M. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2007,15(10):1101-1110
An on-chip multichannel waveform monitoring technique enhances built-in test and diagnostic capabilities of systems- on-a-chip (SoC) integration. The proposed multichannel monitor includes multiple probing front-end modules and a single shared waveform acquisition kernel that consists of an incremental variable step delay generator and an incremental reference voltage generator, featuring adaptive sample time generation for the operation of a target circuit and unidirectional waveform acquisition flow for area-efficient control. A 16-channel prototype in 0.18-mum CMOS technology demonstrated on-chip waveform acquisition at 40-ps and 200-muV resolutions. Combined on- and off-chip streamed-bit processing achieves background continuous waveform acquisition at 260 ms per single timing point for repetitive signals, while eliminating the integration of on-die high-capacity memory. A 700 mum times 600 mum area was occupied by a waveform acquisition kernel and an additional 60 mum times 100 mum area for each front-end module. The developed on-chip multichannel waveform monitoring technique is waveform accurate, area efficient, and suitable for diagnosis toward power supply and signal integrity in analog and digital circuits in mixed-signal SoC integration. 相似文献