全文获取类型
收费全文 | 123594篇 |
免费 | 12906篇 |
国内免费 | 6858篇 |
学科分类
工业技术 | 143358篇 |
出版年
2024年 | 505篇 |
2023年 | 1646篇 |
2022年 | 3288篇 |
2021年 | 4218篇 |
2020年 | 4683篇 |
2019年 | 3761篇 |
2018年 | 3466篇 |
2017年 | 3999篇 |
2016年 | 4577篇 |
2015年 | 4752篇 |
2014年 | 7977篇 |
2013年 | 7733篇 |
2012年 | 9536篇 |
2011年 | 9751篇 |
2010年 | 6862篇 |
2009年 | 6850篇 |
2008年 | 6229篇 |
2007年 | 7544篇 |
2006年 | 7438篇 |
2005年 | 6228篇 |
2004年 | 5312篇 |
2003年 | 4695篇 |
2002年 | 3931篇 |
2001年 | 3434篇 |
2000年 | 2898篇 |
1999年 | 2336篇 |
1998年 | 1815篇 |
1997年 | 1515篇 |
1996年 | 1218篇 |
1995年 | 1047篇 |
1994年 | 937篇 |
1993年 | 636篇 |
1992年 | 521篇 |
1991年 | 434篇 |
1990年 | 353篇 |
1989年 | 323篇 |
1988年 | 186篇 |
1987年 | 133篇 |
1986年 | 105篇 |
1985年 | 90篇 |
1984年 | 70篇 |
1983年 | 51篇 |
1982年 | 52篇 |
1981年 | 69篇 |
1980年 | 51篇 |
1979年 | 16篇 |
1977年 | 10篇 |
1975年 | 8篇 |
1959年 | 10篇 |
1951年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
51.
B. S. Seplyarskii S. V. Kostin G. B. Brauer 《International Journal of Self-Propagating High-Temperature Synthesis》2008,17(2):121-124
Explored is the filtration combustion in Ti-(Ti + 0.5C) layered powder systems in a coflow of nitrogen gas. The presence/absence
of nitrogen coflow through the layered system was found to drastically affect the character of wave propagation and structure/properties
of product. The obtained data can be regarded as a basis for fabrication of new layered and composite materials in the mode
of dynamic filtration combustion.
相似文献
52.
厦门市气源转换的技术分析 总被引:3,自引:2,他引:1
分析了气源转换时原有输配系统的管道、调压设备、计量设备、用气设备与天然气系统相适应的问题,提出了相应的措施。 相似文献
53.
低工作温度的氧化钨气敏材料 总被引:3,自引:0,他引:3
本文报道了一种可以在100℃左右工作的氢化钨气敏材料,它对氢气和一氧化氮有很高的灵敏度和良好的选择性,并可对空气中的一氧化氮进行探测 相似文献
54.
Personal exposure in a displacement ventilated room is examined. The stratified flow and the considerable concentration gradients necessitate an improvement of the widely used fully mixing compartmental approach. The exposure of a seated and a standing person in proportion to the stratification height is examined by means of full-scale measurements. A breathing thermal manikin is used to simulate a person. It is found that the flow in the boundary layer around a person is able to a great extent to entrain and transport air from below the breathing zone. In the case of non-passive, heated contaminant sources, this entrainment improves the indoor air quality. Measurements of exposure due to a passive contaminant source show a significant dependence on the flow field as well as on the contaminant source location. Poor system performance is found in the case of a passive contaminant released in the lower part of the room close to the occupant. A personal exposure model for displacement ventilated rooms is proposed. The model takes the influence of gradients and the human thermal boundary layer into account. Two new quantities describing the interaction between a person and the ventilation are defined. 相似文献
55.
V. V. Skorokhod M. B. Shtern A. V. Kuz’mov A. V. Ragulya 《Powder Metallurgy and Metal Ceramics》2006,45(5-6):221-225
A study has been made on the effects of loading scheme and conditions restricting macroscopic strain on the work-hardening
kinetics and strain accumulation in the solid state in sintering materials with bimodal pore size distributions. Active loading
intensifies the reduction in the small pores. The greatest effect comes from combining sintering with hydrostatic compression.
At the same time, kinematic constraints (partial or complete adhesion in surfaces) substantially retards the shrinkage of
large pores, which means that the porous structure can be controlled.
__________
Translated from Poroshkovaya Metallurgiya, Nos. 5–6(449), pp. 10–15, May–June, 2006. 相似文献
56.
随着我国经济的迅速发展,能源消耗不断增加,节约能源、降低能源消耗势在必行,余热利用是节约能源的一个重要环节,冶金行业高炉冲渣水作为采暖热媒可以节约大量能源。 相似文献
57.
Yutaka Kokai Akira Fukuhara Ken'Ichi Morita Tatsunori Kanke Mamoru Kata Tatsuo Hayashi Toru Takenuki 《Electrical Engineering in Japan》1992,112(6):59-74
Electric power systems are expanding in size and complexity, and the requirement for the energy management system (EMS) is becoming more important. In this computer control system, a single control computer is used mainly as the primary computer and its software is very complicated because of its hugh number of small, quick tasks to obtain high response speed. Therefore, much effort is needed to develop and modify the programs, and the responsiveness of this centralized architecture varies greatly when many faults occur in the power system. This paper describes a new distributed architecture for the EMS. Distributed processors execute the functions cooperatively with periodic access to the common bulletin board database in which information about the power system exist. This architecture facilitates the software development and maintenance, and it also enhances the performance by the parallel processing of the distributed functions. 相似文献
58.
Ronald W. Rousseau James K. Ferrell Robert M. Kelly 《Chemical Engineering Communications》1985,34(1):27-35
Experience with the operation of a pilot-scale unit is used to outline potential difficulties in the operation of acid gas removal systems on gases produced from coal. The pilot plant has been used to condition gases produced from subbituminous coal, devolatilized char, peat and lignite. The solvent used in the acid gas removal system has been refrigerated methyl alcohol. Data from this study document accumulation of hydrocarbons, sulfur and nitrogen compounds, and mercury in the circulating solvent. 相似文献
59.
A novel current source inverter system interconnected to the single‐phase grid is proposed. It has the same construction as the conventional three‐phase current source inverter that is interconnected to the single‐phase three‐wire distribution system. Though the proposed circuit has no output transformer, it can be equivalently performed as the single‐phase double cascade inverter by diverting the pole transformer in the utility system. By controlling the appropriate scheme, the output currents can be obtained as the five‐level waveforms and their distortions can be decreased sufficiently. It is applied to the interactive electric energy storage system with batteries and the basic discharging characteristics are discussed experimentally. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 50–61, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10380 相似文献
60.
There have been extensive attempts in recent years to perform spatial equilibrium analysis of commodity markets, particularly that of energy. Most of these attempts have been based on linear programming transportation models, and more recently quadratic programming models. Unfortunately, neither of these modelling approaches can deal with the case of multi-commodity analysis with non-symmetric regression coefficients. In this paper, we overcome this problem by employing the linear complementarity programming model. In addition, we show how the model can be applied to coal and gas energy flows within a single region. Future potential applications of the model are also implied. 相似文献