全文获取类型
收费全文 | 825篇 |
免费 | 16篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 58篇 |
化学工业 | 151篇 |
金属工艺 | 30篇 |
机械仪表 | 21篇 |
建筑科学 | 21篇 |
矿业工程 | 1篇 |
能源动力 | 24篇 |
轻工业 | 64篇 |
水利工程 | 1篇 |
无线电 | 69篇 |
一般工业技术 | 150篇 |
冶金工业 | 163篇 |
原子能技术 | 30篇 |
自动化技术 | 61篇 |
出版年
2023年 | 4篇 |
2022年 | 11篇 |
2021年 | 17篇 |
2020年 | 10篇 |
2019年 | 9篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 16篇 |
2015年 | 10篇 |
2014年 | 22篇 |
2013年 | 42篇 |
2012年 | 37篇 |
2011年 | 32篇 |
2010年 | 31篇 |
2009年 | 38篇 |
2008年 | 43篇 |
2007年 | 26篇 |
2006年 | 26篇 |
2005年 | 15篇 |
2004年 | 15篇 |
2003年 | 26篇 |
2002年 | 21篇 |
2001年 | 12篇 |
2000年 | 14篇 |
1999年 | 17篇 |
1998年 | 69篇 |
1997年 | 30篇 |
1996年 | 32篇 |
1995年 | 19篇 |
1994年 | 16篇 |
1993年 | 23篇 |
1992年 | 15篇 |
1991年 | 13篇 |
1990年 | 4篇 |
1989年 | 9篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 17篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 12篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1962年 | 1篇 |
排序方式: 共有844条查询结果,搜索用时 15 毫秒
1.
Anumberoflanthanideternarycomplexescon tainingheterocyclicamineshavebeenreportedsince1960 [1] .Inrecentyearsmuchattentionhasbeenpaidtoquaternarycomplexesoflanthanidesbecauseofin terestingstructure ,coordinationmode ,competitionre actionandproperty[2~ 9] .ESRcane… 相似文献
2.
Hitoshi Kurokawa Taku Nakayama Yasunori Kobayashi Ken Suzuki Mutsumi Takahashi Seiichi Takami Momoji Kubo Naotsugu Itoh Parasuraman Selvam Akira Miyamoto 《Catalysis Today》2003,82(1-4):233-240
A modified Monte Carlo (MC) simulation was performed to investigate the hydrogen absorption behavior in Pd and Pd–Ag alloys of the composition PdxAg1−x (x=0.7–0.8) under H2 pressure (0.1 MPa) at different temperatures. The present method employed can consider the dissociative adsorption of hydrogen molecule and the subsequent absorption of hydrogen atom by formalizing the relationship between the pressure of hydrogen molecule and hydrogen atom. The potential parameters were determined to reproduce the solution enthalpy of hydrogen in pure metals. The results are in good agreement with experimental findings as well as previous theoretical studies. We confirmed that our method is useful to simulate the absorption of hydrogen in metals and alloys. 相似文献
3.
4.
Masahide Hojo Yasunori Mitani Toshifumi Ise Kiichiro Tsuji 《Electrical Engineering in Japan》2002,138(3):43-51
The advancement of power electronics technologies has significantly developed the power system stabilizing controllers. Quantitative as well as qualitative evaluation of their effectiveness in power systems is a matter of great importance for the feasibility investigation of these apparatus. In this paper, the possible control region of FACTS controllers with series and/or shunt configuration in a single machine to infinite bus system is formulated in the powerangle curve with a set of algebraic equations. The effectiveness of TCPST (Thyristor‐Controlled Phase Shifting Transformer), SSSC (Static Synchronous Series Compensator), and TCSC (Thyristor‐Controlled Series Compensator) for the improvement of the transient stability is evaluated quantitatively as a numerical example. The correctness of the proposed method has been confirmed by analysis based on the electromagnetic transients simulation with a detailed system model. © 2001 Scripta Technica, Electr Eng Jpn, 138(3): 43–51, 2002 相似文献
5.
6.
Takada K. Kitagawa T. Hattori K. Yamada M. Horiguchi M. Hickernell R.K. 《Electronics letters》1992,28(20):1889-1891
The group delay and dispersion, including the erbium ion contributions, of the highly erbium-doped silica planar waveguide amplifier and multicomponent glass fibre amplifiers are directly measured at different pump powers using a low coherence reflectometer and dispersive Fourier spectroscopy. This method derives the refractive index spectra of these amplifiers directly from the produced reflectograms without any physical or mathematical assumptions. The dispersion of the planar waveguide amplifier at 500 mW pumping changes between +300 and -200 ps/km/nm with a 0.4 wt.% erbium concentration.<> 相似文献
7.
8.
K Ueda K Kitagawa M Kadoya O Matsui T Takashima T Yamahana 《Canadian Metallurgical Quarterly》1995,20(6):547-553
BACKGROUND: Most hepatocellular carcinomas (HCCs) are hypervascular and arise in the liver with chronicity. Spiral volumetric CT (SVCT) is a new rapid-scan technique that offers whole-liver scanning during the arterial-dominant phase. The main aim of the present study is to evaluate the detectability of hypervascular HCC with SVCT as compared with ultrasonography (US) and magnetic resonance (MR) imaging. METHODS: Forty-three hypervascular HCCs in 512 patients with chronic liver disease were examined with US, precontrast SVCT, postcontrast SVCT during the arterial-dominant phase (CT-ADP) and during the equivalent-phase (CT-EP) noncontrast MR imaging and angiography including SVCT during arteriography and arterial portography. Angiographic and follow-up findings were used as the gold standard if the lesion was not confirmed histologically. RESULTS: The sensitivity was 61% with precontrast CT, 84% with CT-ADP, 58% with CT-EP, 70% with US, 72% with MR, and 95% with the combination of these five modalities. Five HCCs (12%) were detected with only CT-ADP. The vascularity of HCC was correctly evaluated as hypervascular in 38 nodules (88%) with the combination of precontrast CT and CT-ADP. CONCLUSIONS: We suggest that the combination of precontrast SVCT and CT-ADP is an essential modality to screen for HCC in patients with chronic liver disease. CT-EP did not contribute to the detection of hypervascular HCC. 相似文献
9.
10.
Kojiro Nakai Yasunori Oumi Haruyuki Horie Tsuneji Sano Hideaki Yoshitake 《Microporous and mesoporous materials》2007,100(1-3):328-339
Bromination and subsequent ethylenediamine substitution of the CC double bond in mesoporous ethylenesilica were carried out to explore the characteristics of this periodic mesoporous organosilica. The structures of the products (BrPMO and EDA–BrPMO, respectively) were analysed by IR, Br K-edge EXAFS and NMR spectroscopies, as well as X-ray diffraction and nitrogen adsorption. We showed (1) that the formulae of the two products that formed were [CHBrSiO1.5]0.45[CHSiO1.5]0.55 and [NH2CH2CH2NHCHSiO1.5]0.05 [CHBrSiO1.5]0.40[CHSiO1.5]0.55, respectively, (2) that the addition of Br2 at room temperature occurred on the CC double bonds with disturbing the framework structure, (3) that IR absorption band of CC bonds that reacted with Br2 is significantly different from that of inactive CC bond, (4) that the length of the C–Br bond was considerably longer than in conventional alkyl bromides, and (5) that a large proportion of the ν(C–Br) band remained at the same position in the IR absorption spectrum after the ethylenediamine (EDA) substitution, while a new ν(C–Br) absorption also appeared. The mechanisms of these reactions are discussed at both the micro and mesoscopic levels.
Arsenate adsorption on EDA–BrPMO, in which the EDA is directly bound to the “surface” of the mesopores, was compared with adsorption on EDA–Pr–PMO, which was prepared by the direct synthesis of 3-chloropropyl-functionalized mesoporous ethanesilica followed by the substitution of Cl with EDA. The strength of the adsorption, as measured with the distribution coefficient, was greater for the former adsorbent than the latter. The origin of this difference was attributed to the distance between amino group and the surface. 相似文献