全文获取类型
收费全文 | 1915篇 |
免费 | 36篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 81篇 |
综合类 | 4篇 |
化学工业 | 358篇 |
金属工艺 | 67篇 |
机械仪表 | 32篇 |
建筑科学 | 17篇 |
能源动力 | 50篇 |
轻工业 | 183篇 |
水利工程 | 7篇 |
石油天然气 | 1篇 |
无线电 | 204篇 |
一般工业技术 | 345篇 |
冶金工业 | 468篇 |
原子能技术 | 44篇 |
自动化技术 | 91篇 |
出版年
2023年 | 6篇 |
2022年 | 23篇 |
2021年 | 25篇 |
2020年 | 16篇 |
2019年 | 17篇 |
2018年 | 19篇 |
2017年 | 24篇 |
2016年 | 34篇 |
2015年 | 19篇 |
2014年 | 32篇 |
2013年 | 70篇 |
2012年 | 48篇 |
2011年 | 99篇 |
2010年 | 64篇 |
2009年 | 61篇 |
2008年 | 81篇 |
2007年 | 77篇 |
2006年 | 36篇 |
2005年 | 42篇 |
2004年 | 50篇 |
2003年 | 41篇 |
2002年 | 40篇 |
2001年 | 37篇 |
2000年 | 42篇 |
1999年 | 43篇 |
1998年 | 152篇 |
1997年 | 123篇 |
1996年 | 100篇 |
1995年 | 51篇 |
1994年 | 50篇 |
1993年 | 45篇 |
1992年 | 29篇 |
1991年 | 27篇 |
1990年 | 22篇 |
1989年 | 31篇 |
1988年 | 12篇 |
1987年 | 25篇 |
1986年 | 26篇 |
1985年 | 16篇 |
1984年 | 24篇 |
1983年 | 20篇 |
1982年 | 19篇 |
1981年 | 17篇 |
1980年 | 16篇 |
1979年 | 19篇 |
1978年 | 11篇 |
1977年 | 22篇 |
1976年 | 26篇 |
1974年 | 5篇 |
1973年 | 5篇 |
排序方式: 共有1952条查询结果,搜索用时 71 毫秒
991.
Asakawa A. Miyake K. Yokoyama S. Shindo T. Yokota T. Sakai T. 《Power Delivery, IEEE Transactions on》1997,12(3):1222-1231
To clarify the characteristics of lightning on the coast of the Sea of Japan in the winter season, the current waveform and the progression of lightning discharge to a high stack were observed. Observation results from 1989 to 1994 show that: (1) there are two types of lightning discharges-one with large currents and strong luminosity in the lightning path, and the other with small currents of long duration and weak luminosity of lightning path; (2) the parameters of lightning currents of the two types of discharges are quite different; and (3) there is a quantitative correlation between the change of luminosity in a lightning path and the lightning current waveform 相似文献
992.
Sakai Y. Kurosaki T. Sato R. Tohmori Y. Suzuki S. Mitomi O. Sugie T. 《Electronics letters》1995,31(21):1858-1860
Dynamic characteristics are clarified for a laser diode integrated with a spot-size converter coupled to a silica planar lightwave circuit. The laser was developed with a butt-jointed selectively grown spot-size converter. A maximum coupling efficiency of -0.74 dB was achieved. Bit error rate performances are estimated to clarify the allowable reflection when optical feedback from the fibre output end occurs 相似文献
993.
Birch J.R. Simonis G.J. Afsar M.N. Clarke R.N. Dutta J.M. Frost H.M. Gerbaux X. Hadni A. Hall W.F. Heidinger R. Ho W.W. Jones C.R. Koniger F. Moore R.L. Matsuo H. Nakano T. Richter W. Sakai K. Stead M.R. Stumper U. Vigil R.S. Wells T.B. 《Microwave Theory and Techniques》1994,42(6):956-965
The results of a measurement intercomparison aimed at assessing the systematic errors in near-millimetre-wavelength dielectric measurements on reasonably transparent solid specimens are presented and discussed. Various monochromatic, broad band, guided wave and free space measurement methods were intercompared in the frequency region from 30 to 900 GHz using round-robin measurements of the refractive index and absorption coefficient of seven specimens. Typically, systematic errors of up to 1% were found in the refractive index results, while very much larger systematic errors were found in the absorption results 相似文献
994.
Frequency response of the glucose/maltose biosensors based on immobilized glucoamylase and glucose oxidase membranes of different thickness were investigated with the sinusoidal signal generator of substrate concentration. The results were modeled by the serial combination of the dead time and the first order response blocks, and time constants and dead times were estimated. The estimated value of time constant ranged from 4.5 to 13.2 s and that of the dead time from 3.2 to 7.7 s with the tendency that both time constant and dead time increase as membrane thickness increases and number of enzymatic reaction steps increases. 相似文献
995.
A 39-year-old male presented with a putaminal hemorrhage. Angiography disclosed the incidental findings of association of basilar artery fenestration and persistent primitive trigeminal artery. This is the first report of this association of congenital anomalies of the cerebral vessels. 相似文献
996.
T Yamazaki Y Shirai T Tada M Sasaki Y Sakai K Hatakeyama 《Canadian Metallurgical Quarterly》1997,27(5):460-462
There are several weak points in the colonic blood supply, known as watershed areas, which result from incomplete anastomoses of the marginal arteries. These watershed areas are more vulnerable to ischemic injury than other parts of the colon. We report herein the cases of two patients who developed ischemic colitis well localized in the cecum, and in the rectosigmoid region at Sudeck's point, respectively. This report and our review of the literature suggest that watershed areas, including the splenic flexure, or Griffith's point, Sudeck's point, and the ileocecal region, are high-risk regions for the development of ischemic colitis. 相似文献
997.
Oohashi H. Fukuda M. Kondo Y. Wada N. Tohmori Y. Sakai Y. Toba H. Itaya Y. 《Lightwave Technology, Journal of》1998,16(7):1302-1307
This paper discusses the degradation behaviors and reliability of spot-size converter integrated laser diodes fabricated using the full wafer process with dry etching and metal organic vapor phase epitaxy (MOVPE). Failure criteria applicable to actual access networks were determined based on the degradation behavior exhibited in several aging tests, and device lifetimes were then estimated. The far-field patterns and wide-temperature operation required for low-cost system application scarcely changed during degradation, even after a 150% increase in threshold current. Within this degradation range, the device life for system application is estimated to be more than 105 h at 60°C and 10 mW 相似文献
998.
K Sakai M Akima S Kamachi M Moriyasu S Kitajima 《Canadian Metallurgical Quarterly》1998,50(6):661-666
OBJECTIVE: To determine the reproducibility of duplex Doppler waveform analysis and fetal cardiac interventricular septal thickness measurement and to compare these parameters in matched pregnancies with and without well-controlled maternal Type 1 diabetes at 18-20 weeks of gestation. DESIGN: A prospective blind twin cohort study and a blinded inter-observer and intra-observer agreement study. SETTING: A tertiary referral prenatal diagnostic unit within a university hospital. RESULTS: Good inter- and intra-observer agreement was found for the measurement of transvalvular peak flow velocities and the duration of ventricular ejection in the fetal heart. Inter-observer agreement for aortic flow acceleration rate was poor. M-mode measurement of interventricular septal thickness showed moderate reproducibility. The mean (SD) width of the interventricular septum in the fetuses of well controlled diabetic women was 2 1 mm (0.2 mm), and was significantly greater (P=0.01) when compared with the corresponding value in matched controls [1.9 mm (0.2 mm)]. No cardiac functional differences were evident. CONCLUSIONS: On-screen video analysis of Doppler cardiac flow waveforms and M-mode measurement of intraventricular septal thickness demonstrated good reproducibility. The fetuses of well controlled diabetic pregnancies demonstrated signs of altered cardiac morphology early in pregnancy, before any evident alterations in cardiac function. 相似文献
999.
S Nemoto A Sakai K Sudoh K Kodera M Abe ZB Lim M Oosawa 《Canadian Metallurgical Quarterly》1997,50(12):1049-1051
We experienced a case of dysfunction of Carpentier-Edwards pericardial bioprosthesis in the tricuspid position. Explanted bioprosthesis showed overgrowth of neointima from ring to cusps and adhesion to remnants of native cusps. This restricted the motion of the pericardial leaflets resulting in orifice stenosis. Care must be taken in such valve replacement by this prosthesis leaving native valve tissue. 相似文献
1000.