全文获取类型
收费全文 | 3279篇 |
免费 | 64篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 219篇 |
综合类 | 4篇 |
化学工业 | 691篇 |
金属工艺 | 87篇 |
机械仪表 | 67篇 |
建筑科学 | 56篇 |
矿业工程 | 1篇 |
能源动力 | 130篇 |
轻工业 | 273篇 |
水利工程 | 18篇 |
石油天然气 | 1篇 |
无线电 | 355篇 |
一般工业技术 | 496篇 |
冶金工业 | 589篇 |
原子能技术 | 82篇 |
自动化技术 | 283篇 |
出版年
2023年 | 11篇 |
2022年 | 38篇 |
2021年 | 58篇 |
2020年 | 30篇 |
2019年 | 35篇 |
2018年 | 44篇 |
2017年 | 30篇 |
2016年 | 47篇 |
2015年 | 36篇 |
2014年 | 86篇 |
2013年 | 159篇 |
2012年 | 116篇 |
2011年 | 148篇 |
2010年 | 121篇 |
2009年 | 153篇 |
2008年 | 143篇 |
2007年 | 116篇 |
2006年 | 102篇 |
2005年 | 107篇 |
2004年 | 81篇 |
2003年 | 83篇 |
2002年 | 93篇 |
2001年 | 54篇 |
2000年 | 77篇 |
1999年 | 87篇 |
1998年 | 238篇 |
1997年 | 141篇 |
1996年 | 122篇 |
1995年 | 82篇 |
1994年 | 75篇 |
1993年 | 85篇 |
1992年 | 58篇 |
1991年 | 40篇 |
1990年 | 30篇 |
1989年 | 40篇 |
1988年 | 40篇 |
1987年 | 17篇 |
1986年 | 21篇 |
1985年 | 36篇 |
1984年 | 31篇 |
1983年 | 22篇 |
1982年 | 27篇 |
1981年 | 29篇 |
1980年 | 28篇 |
1979年 | 23篇 |
1978年 | 18篇 |
1977年 | 27篇 |
1976年 | 21篇 |
1974年 | 9篇 |
1967年 | 9篇 |
排序方式: 共有3352条查询结果,搜索用时 15 毫秒
1.
2.
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
3.
J.H. Kaneko T. Tanaka S. Kawamura Y. Oshiki K. Tsuji M. Katagiri K. Ochiai T. Nishitani F. Fujita A. Homma T. Sawamura T. Iida M. Furusaka 《Diamond and Related Materials》2005,14(11-12):2027
Radiation detector was made of a high-quality CVD polycrystalline diamond composed of frost column like structure diamond grains, and induced charge distribution spectra and drift velocities were measured by using alpha particles. As a result, the CVD polycrystalline achieved maximum induced charge of 83% of HP/HT type IIa diamond. Moreover, the CVD crystal had lower charge loss on electrons compared with the HP/HT type IIa diamond. Drift velocities of electrons and holes were ve = 7.7 × 104 and vh = 7.3 × 104cm/s at an electric field of 20 kV/cm, respectively. In addition, response function measurement for 14 MeV neutrons was carried out. 相似文献
4.
Koji Kamei Kunihiko Fujita Eva Jettmar Sen Yoshida Kazuhiro Kuwabara 《Interacting with computers》2002,14(6):438-759
In this paper, we present and discuss Community Organizer, a system designed to support network communities. The main characteristic of Community Organizer is the use of spatial representations for the relationships among community members including the communications exchanged among these members. These spatial representations reflect the degree of closeness of interests and concerns among the members, and are intended to provide users with clues on how to form network communities. In order to investigate the effectiveness of the proposed spatial representations, we conducted experiments with two different versions of the software. One version offered meaningful spatial representations while the other version did not. The subjects who used the former software version felt a greater sense of ‘community’, enjoyed using the software more, and actively used it longer than the subjects using the latter software version (control condition). These results indicated that the proposed spatial representations are effective in supporting network community formation. 相似文献
5.
A floating-gate analog memory device for neural networks 总被引:1,自引:0,他引:1
A floating-gate MOSFET device that can be used as a precision analog memory for neural network LSIs is described. This device has two floating gates. One is a charge-injection gate with a Fowler-Nordheim tunnel junction, and the other is a charge-storage gate that operates as a MOSFET floating gate. The gates are connected by high resistance, and the charge-injection gate is small so that its capacitance is much less than that of the charge-storage gate. By applying control pulses to the charge-injection gate, it is possible to charge and discharge the MOSFET floating gate in order to modify the MOSFET current with high resolution over 10 b. The charge injection can be carried out without disturbing the MOSFET output current with high voltage control pulses. This device is useful for on-chip learning in analog neural network LSIs 相似文献
6.
Shijie Zhu Yutaka Kagawa Jian-Wu Cao Mineo Mizuno 《Metallurgical and Materials Transactions A》2004,35(9):2853-2859
Time-dependent deformation in an enhanced SiC/SiC composite has been studied under constant load at high temperatures of 1200
°C, 1300 °C, and 1400 °C. Creep damage evolution was evaluated by a Young’s-modulus change of partial unloading and microscopic
observation. The addition of the glassy phase in the matrix is very effective for protecting the composite from oxidation.
The transient creep is dominant in creep life at all the temperatures. An empirical equation is proposed to describe creep
behavior of the composite. It is found that creep activation energy increases with creep time at stresses lower than matrix
cracking stress, but the activation energy remains constant at stresses higher than the matrix cracking stress. The creep
strain rate of the composite is considered to be controlled by creep of fibers based on examining the time, strain, stress,
and temperature dependencies of creep strain rates. 相似文献
7.
An applicability of quinone biomarker to the analysis of hillslope runoff was investigated. At first, quinone profiles of three streams as well as a hillslope runoff in a forested headwater catchment were compared. The quinone composition of hillslope runoff differed from others. Moreover, there were remarkable differences in quinone profile of hillslope runoff under different rainfall conditions. Then, the behavior of quinone biomarker during the increase and decrease of hillslope runoff after a rainfall event was examined. The fractional changes in Q-9 (H2), Q-10 (H2), Q-11, MK-6 and MK-10 suggested the effect of interflow. 相似文献
8.
9.
This paper deals with an advanced static Var compensator (ASVC) using quad-series voltage-source PAM inverters. The ASVC consists of four three-phase voltage-source inverters with a common dc capacitor and four three-phase transformers, each primary winding of which is connected in series with each other. Each inverter outputs a square-wave voltage, while the synthesized output voltage of the ASVC has a 24-step wave shape. This results not only in a great reduction of harmonic currents and dc voltage ripples but also in fewer switching and snubbing losses. In this paper, transient analysis is performed with the focus on the response of reactive power and the resonance between the dc capacitor and ac reactors. Experimental results obtained from a small-rated laboratory model of 10 kVA are also shown to verify analytical results based on the p-q transformation. The analytical results help in the design of system parameters such as the capacity of the dc capacitor and feedback gains. 相似文献
10.
We reported five patients with purple urine bag syndrome (PUBS). Four patients had indicanuria, and, in three of them, purple pigmentation was reproduced by inoculating urinary isolates, in the broth with indoxyl sulfate. Klebsiella pneumoniae, Pseudomonas aeruginosa and Enterococcus avium were considered to produce the purple pigment in three patients. However, attempts to reproduce the purple pigment failed in two patients, and one of them did not have indicanuria. These results suggest that indicanuria is not necessarily required for the development of PUBS. 相似文献