全文获取类型
收费全文 | 8041篇 |
免费 | 364篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 123篇 |
综合类 | 4篇 |
化学工业 | 2068篇 |
金属工艺 | 152篇 |
机械仪表 | 203篇 |
建筑科学 | 311篇 |
矿业工程 | 11篇 |
能源动力 | 297篇 |
轻工业 | 939篇 |
水利工程 | 53篇 |
石油天然气 | 30篇 |
无线电 | 768篇 |
一般工业技术 | 1422篇 |
冶金工业 | 858篇 |
原子能技术 | 78篇 |
自动化技术 | 1100篇 |
出版年
2023年 | 50篇 |
2022年 | 146篇 |
2021年 | 204篇 |
2020年 | 136篇 |
2019年 | 173篇 |
2018年 | 197篇 |
2017年 | 227篇 |
2016年 | 244篇 |
2015年 | 176篇 |
2014年 | 263篇 |
2013年 | 462篇 |
2012年 | 410篇 |
2011年 | 461篇 |
2010年 | 373篇 |
2009年 | 407篇 |
2008年 | 360篇 |
2007年 | 373篇 |
2006年 | 337篇 |
2005年 | 245篇 |
2004年 | 239篇 |
2003年 | 211篇 |
2002年 | 195篇 |
2001年 | 157篇 |
2000年 | 134篇 |
1999年 | 124篇 |
1998年 | 250篇 |
1997年 | 205篇 |
1996年 | 153篇 |
1995年 | 136篇 |
1994年 | 125篇 |
1993年 | 113篇 |
1992年 | 68篇 |
1991年 | 56篇 |
1990年 | 69篇 |
1989年 | 56篇 |
1988年 | 72篇 |
1987年 | 53篇 |
1986年 | 36篇 |
1985年 | 86篇 |
1984年 | 61篇 |
1983年 | 56篇 |
1982年 | 46篇 |
1981年 | 82篇 |
1980年 | 49篇 |
1979年 | 52篇 |
1977年 | 41篇 |
1976年 | 51篇 |
1975年 | 41篇 |
1974年 | 33篇 |
1973年 | 27篇 |
排序方式: 共有8417条查询结果,搜索用时 0 毫秒
51.
We compute the temperature dependent magnetic susceptibility of the single-impurity, two-channel Anderson model with an alternative multi-step numerical renormalization-group transformation, previously applied only to the two-impurity single-channel Kondo model. Compared with the traditional transformation, the new procedure requires substantially less memory and computational time, and opens therefore perspectives for the application of the numerical renormalization-group procedure to more complex Hamiltonians. 相似文献
52.
Weldable primers are thin zinc-rich organic coatings that are weldable due to the electrical conductivity provided by the zinc dust. They are used in the automotive industry to provide corrosion protection in regions of difficult access. The zinc particles are highly susceptible to corrosion attack and, due to the small thickness, the protection conferred by these systems is limited. 相似文献
53.
54.
F. Adrian M. Rü bsam K. -P. Dinse D. Fuchs H. Rietschel R. H. Michel M. Benz M. M. Kappes 《Fullerenes, Nanotubes and Carbon Nanostructures》1996,4(4):655-675
From the analysis of the temperature dependence of the EPR line width, an estimate of the anisotropic parts of the dipolar and quadrupolar hyperfine couplings of lanthanum was derived. Furthermore, the rotational correlation time of the nearly spherical molecule was found to deviate considerably from that of the solvent molecules. 相似文献
55.
Hofsajer I.W. Ferreira J.A. van Wyk J.D. Holm M.F.K. 《Industry Applications Magazine, IEEE》1995,1(5):24-29
In order to reduce the cost, size, and weight of power electronic systems, it has become necessary to integrate electromagnetic structures, which until now have been constructed with discrete components. This approach not only reduces the component count, but also gives much greater control over parasitic elements. In this article, the authors describe an electromagnetically integrated resistor-capacitor-diode (RCD) snubber/voltage clamp that uses a planar construction technique. The design and construction are described and the performance is verified experimentally. Some advantages of the integrated component over its discrete counterpart are also given 相似文献
56.
CE Michel 《Canadian Metallurgical Quarterly》1996,114(9):1134-5; discussion 1135
57.
P Demoly D Jaffuel KF Chung J Bousquet FB Michel P Godard 《Canadian Metallurgical Quarterly》1996,25(40):2025-2030
The efficacy of corticosteroids in asthma has been recognized over 40 years ago. Since that time, the advent of inhaled forms has further improved the therapeutic of these drugs which are now recognized as the fundamental treatment for asthma, and described in detail by national and international consensus. Based on a large body of literature, it can now be recommended to prescribe inhaled corticosteroids for symptomatic asthma patients. Long-term treatment is required and dosage not exceeding 1000 micrograms/d (beclometasone dipropionate equivalent) in adults are safe. Differences in the pharmacological characteristics of the various systematic and inhaled corticosteroids can be used to adapt treatment and administration route to each patient and achieve good patient compliance with optimal therapeutic efficacy. 相似文献
58.
Zakaria Chajar Michel Primet Hélène Praliaud Michèle Chevrier Catherine Gauthier Frédéric Mathis 《Catalysis Letters》1994,28(1):33-40
The role of nitrogen dioxide in the selective reduction of NO by propane over a Cu-MFI zeolite is investigated. NO2 and NO reductions were carried out under similar conditions of reaction. In the presence of oxygen, the reduction of NO by C3H8 does not differ significantly from that of NO2. In the absence of oxygen, the reduction of NO2 by propane occurs with a partial decomposition of the nitric dioxide molecule. Such a decomposition leads to the formation of oxygen, which is responsible for the increase in catalytic activity by comparison with the same reaction performed with NO. NO2 formed and released in the gas phase during the reduction of NO by propane in the presence of oxygen does not play a predominant role in the catalytic process. 相似文献
59.
Quasistatic error sources, which include thermal, mechanical loading and geometric error sources, are responsible for a very large proportion (typically, 70%) of the volumetric errors of a numerically controlled machine-tool. This paper, the first in a set of three, discusses the development of a very general model for the effects of geometric errors of the components of the kinematic chain (structural members and axes) of a machine on the volumetric errors in the work space. The effects of the other two sources are modeled as changes in the geometric error. The generality of the model arises from the fact that the errors along an axis of the machine can be characterized by any polynomial functions and the model is recursive in the order of these polynomials. This model can be used as the basis of a compensation scheme as well as in budgeting of errors on a machine-tool. 相似文献
60.