全文获取类型
收费全文 | 641篇 |
免费 | 26篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 36篇 |
综合类 | 1篇 |
化学工业 | 184篇 |
金属工艺 | 10篇 |
机械仪表 | 8篇 |
建筑科学 | 8篇 |
能源动力 | 27篇 |
轻工业 | 57篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 33篇 |
一般工业技术 | 162篇 |
冶金工业 | 81篇 |
原子能技术 | 10篇 |
自动化技术 | 50篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 11篇 |
2019年 | 6篇 |
2018年 | 11篇 |
2017年 | 9篇 |
2016年 | 20篇 |
2015年 | 15篇 |
2014年 | 21篇 |
2013年 | 31篇 |
2012年 | 22篇 |
2011年 | 30篇 |
2010年 | 23篇 |
2009年 | 20篇 |
2008年 | 32篇 |
2007年 | 24篇 |
2006年 | 26篇 |
2005年 | 24篇 |
2004年 | 28篇 |
2003年 | 19篇 |
2002年 | 13篇 |
2001年 | 15篇 |
2000年 | 16篇 |
1999年 | 9篇 |
1998年 | 31篇 |
1997年 | 20篇 |
1996年 | 19篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 11篇 |
1980年 | 4篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1974年 | 2篇 |
1972年 | 3篇 |
1970年 | 3篇 |
排序方式: 共有669条查询结果,搜索用时 15 毫秒
71.
The letter describes a specially designed coiled transducer for the magnetostatic mode. The conversion loss of the magneto-static-mode delay line provided with the proposed transducer has been found reduced down to 10.5 dB at L band. 相似文献
72.
Four coals with similar ultimate analyses were Soxhlet-extracted with pyridine before and after heat treatment at 400 °C and with quinoline at 350 °C. Pyridine extraction yield tended to be proportional to log maximum fluidity (MF), but with some discrepancies. Quinoline extraction yield was more nearly proportional to log MF. However, the best correlation with log MF was obtained for quinoline extraction yield corrected for inert content. 相似文献
73.
Kenji Yura Kazumasa Ohashi Masaru Nakajima Masataka Yoshimura Masaharu Ota Katsundo Hitomi P.E. Econ 《Computers & Industrial Engineering》1994,27(1-4):127-130
A method of developing strategic CIM is described. Relationship between CIM and firm's competitive power is clarified, and a fundamental planning procedure for CIM is developed for enhancing the competitiveness. In the procedure, the system configuration of CIM is analyzed using 0–1 goal programming techniques. A numerical example is also demonstrated to show the effectiveness of the procedure. 相似文献
74.
Methanol, ethanol, straight-chain propanol, isopropanol, straight-chain butanol, sec-butanol, tert-butanol, straight-chain pentanol, and iso-pentanol were used for the reaction of coal with NaOH-alcohol at 290 °C for 1 h. All the products dissolved in pyridine with an extraction yield > 80 wt%. Straight-chain alcohols are less reactive than the secondary alcohols owing to the differences in hydrogen donating ability. 相似文献
75.
Grain-size effects on microwave ferrite magnetic properties 总被引:1,自引:0,他引:1
This paper presents a review of polycrystalline microwave ferrites with specific reference made to the grain size. Fine-grained ferrites and large-grained ferrites as referred to in this article stand for the ferrites with an average grain size of 2 μm or less and those of 100 μm or larger, respectively. Fine-graining of ferrites is one of the state-of-the-arts techniques for obtaining high-power ferrites. Large-graining is a newly developed technique for further improving the family of narrow resonance linewidth garnet materials. Starting with some ceramics-oriented topics including the definition of the average grain-size and so forth, the present review covers the grain-size dependence of initial permeability and the grain-size dependence of microwave properties (ΔH, ΔHeff , and ΔHk ) both in the theoretical and in the experimental phases. Successful device applications of newly developed "single-crystal-like" large-grained ferrites are also reviewed. 相似文献
76.
NitrogenDopingEfectinaGe:HFilmsDueToHighHydrogenDilutionJ.Xu1K.J.Chen1D.Feng1,SeichiMiyazaki2MasatakaHirose2(1.Dept.ofPhysic... 相似文献
77.
Masataka Mizushima 《Journal of Infrared, Millimeter and Terahertz Waves》1982,3(3):379-384
Using the values of the rotational molecular parameters (including cencrifugal distortion terms) of the H2 16O molecule, which can explain 12 observed transitions below 800 GHz, all rotational energy levels with normalized Boltzmann factors larger than 5×10?8 at 300°K are calculated. Probabilities of all possible electric dipole transitions among these states, 2277 lines, are calculated using the eigenfunctions thus obtained, and the permanent electric dipole moment of 1.8546 Debye. Assuming the single and full Lorentzian line forms, we calculated the absorption coefficient for millimeter to submillimeter region. Our result, using the single term Lorentzian line form, agrees quite well with experiment for 1 Torr of water vapor in 760 Torr air at 300°K. 相似文献
78.
Y Yamada K Tsushima Y Sakata S Saito T Ito N Sugimoto H Ogasawara Y Tamura N Moriya Y Komatsu 《Canadian Metallurgical Quarterly》1994,21(7):1029-1032
Forty-two patients with gastric cancer were entered in this study. Forty-one of them were eligible and administered sequential methotrexate (MTX)/5-fluorouracil (5-FU) with 5'-deoxy-5-fluorouridine (5'-DFUR). 5-FU was administered intravenously by drip infusion for 2 hours in 22 cases (group A), and was infused by bolus injection in 19 cases (group B). The treatment schedules were as follows: MTX 100 mg/m2 was given intravenously (i.v.) followed by 5-FU 600 mg/m2 i.v. 2 hours later and leucovorin 15 mg/body i.v. 8 and 20 hours later. This cycle was repeated once a week. 5'-DFUR 1,200 mg/body/day was given orally on 5 consecutive days per week. Three of 20 cases (15%) in group A showed PR, while 5 of 15 cases (33%) in group B showed PR. Median survival time was 2.8 months in group A and 3.7 months in group B. There was, however, no statistical difference. Gastrointestinal toxicity was commonly observed. Leukocytopenia was more severe in group B. Alopecia was more frequently observed in group B (p < 0.025). These results suggested bolus injection of 5-FU was a promising way of administration in sequential MTX/5-FU therapy. 相似文献
79.
Cooling efficiency during transient reflooding under loss of normal coolant conditions has been examined with a 7 × 7 simulated fuel rod bundle and jet pump bypass. The bundle contains 49 electrically heated rods with 3600 mm heated length and a pseudo cosine axial power distribution. Water is injected into the lower plenum and the superheated bundle is reflooded from the bottom with some flow diverted to the simulated jet pump bypass. The results show that effective cooling can be maintained. 相似文献
80.
Low-noise amplifiers for u.h.f. colour t.v. broadcasting translator use have been successfully developed by using 1 ?m gate GaAs m.e.s.f.e.t.s. The obtained performances revealed that a GaAs m.e.s.f.e.t. has low-noise and low intermodulation distortion characteristics, even in the 500?800 MHz frequency range, compared with a Si bipolar transistor. 相似文献