全文获取类型
收费全文 | 22722篇 |
免费 | 2238篇 |
国内免费 | 1391篇 |
专业分类
电工技术 | 2067篇 |
综合类 | 2021篇 |
化学工业 | 2392篇 |
金属工艺 | 1366篇 |
机械仪表 | 2796篇 |
建筑科学 | 3853篇 |
矿业工程 | 1748篇 |
能源动力 | 560篇 |
轻工业 | 1227篇 |
水利工程 | 774篇 |
石油天然气 | 469篇 |
武器工业 | 170篇 |
无线电 | 1872篇 |
一般工业技术 | 2460篇 |
冶金工业 | 879篇 |
原子能技术 | 125篇 |
自动化技术 | 1572篇 |
出版年
2024年 | 102篇 |
2023年 | 355篇 |
2022年 | 514篇 |
2021年 | 669篇 |
2020年 | 789篇 |
2019年 | 586篇 |
2018年 | 609篇 |
2017年 | 680篇 |
2016年 | 757篇 |
2015年 | 878篇 |
2014年 | 1437篇 |
2013年 | 1406篇 |
2012年 | 1624篇 |
2011年 | 1673篇 |
2010年 | 1310篇 |
2009年 | 1428篇 |
2008年 | 1311篇 |
2007年 | 1710篇 |
2006年 | 1469篇 |
2005年 | 1245篇 |
2004年 | 997篇 |
2003年 | 869篇 |
2002年 | 722篇 |
2001年 | 577篇 |
2000年 | 519篇 |
1999年 | 394篇 |
1998年 | 362篇 |
1997年 | 300篇 |
1996年 | 233篇 |
1995年 | 174篇 |
1994年 | 148篇 |
1993年 | 108篇 |
1992年 | 93篇 |
1991年 | 66篇 |
1990年 | 56篇 |
1989年 | 36篇 |
1988年 | 32篇 |
1987年 | 22篇 |
1986年 | 9篇 |
1985年 | 15篇 |
1984年 | 17篇 |
1983年 | 5篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 12篇 |
1977年 | 4篇 |
1966年 | 2篇 |
1959年 | 3篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
介绍液态软起动技术在济钢 15000 m3/h制氧机配套的 6000 kW同步电动机上的应用情况,阐述了系统的原理、特点、仿真计算及实际应用后达到的效果. 相似文献
52.
53.
Using boundary element based three dimensional modelling for linear fracture mechanics, we present an analysis of cracking in a homogeneous medium subject to contact load. The proposed iterative solution procedure allows a simultaneous treatment of a reasonable number of partially closed cracks. It is shown that the most probable direction of propagation of a vertical internal crack is strongly dependent on its size compared to the contact radius and its location with respect to the axis of maximum normal load. 相似文献
54.
Chouping Luo Marek Klisinski 《International journal for numerical methods in engineering》2004,61(2):159-188
The present study is a continuation of our previous work with the aim to reduce problems caused by standard higher order elements in contact problems. The difficulties can be attributed to the inherent property of the Galerkin method which gives uneven distributions of nodal forces resulting in oscillating contact pressures. The proposed remedy is use of piece‐wise linear weight functions. The methods to establish stiffness and/or mass matrix for 8‐node quadrilateral element in 2D are presented, i.e. the condensing and direct procedures. The energy and nodal displacement error norms are also checked to establish the convergence ratio. Interpretation of calculated contact pressures is discussed. Two new 2D 8‐node quadrilateral elements, QUAD8C and QUAD8D, are derived and tested in many examples, which show their good performance in contact problems. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
55.
This study investigates the relationship between the critical surface tension of wetting of celestite and agglomeration recovery as well as the zeta potential in dependence of pH and amount of collector (Na‐Oleate). For this purpose, effects of pH and collector amount on the agglomeration recovery are investigated and zeta potential measurements and Fourier Transform Infrared Spectrophotometer (FTIR) analyses are carried out to determine the adsorption type of Na‐Oleate on celestite surface. The sessile drop technique is used for the measurement of contact angle and determination of the critical surface tension of wetting (YC) of celestite. The maximum agglomeration recovery is obtained at pH 7. The critical surface tension of wetting of celestite is very close to the surface tension of kerosene, which is 25.95 mN/m. Furthermore, at the optimum Na‐Oleate amount of 10 kg/ton, the critical surface tension of wetting of celestite is approximately equal to the surface tension of kerosene. 相似文献
56.
对唐钢薄板坯连铸机生产的SS400钢的生产工艺进行了分析,认为薄板坯连铸机生产的SS400钢,在采取了精炼站在线定氧,将钢水全氧控制在25×10~(-6)左右,同时连铸采取保护浇注和轻压下等技术后,能够确保薄板坯连铸SS400钢的顺利浇注,轧制的板带材表面质量良好,机械性能符合要求。 相似文献
57.
官泓 《有色冶金设计与研究》2003,24(3):49-51
阐述水厂设计中对水厂规模、水源地、净水厂位置及净水工艺的确定过程,根据原水的特点,通过分析对无阀滤池进行改良。 相似文献
58.
Gouvier W. Drew; Sytsma-Jordan Sara; Mayville Stephen 《Canadian Metallurgical Quarterly》2003,48(3):175
Objective: To evaluate the effects of disability type, job complexity, and public contact on hiring decisions. Design and Participants: An Americans With Disabilities Act (ADA; 1990) fact sheet and matched resumes with vocational and medical histories including chronic mental illness, developmental disability, closed head injury, and back injury were provided to 295 undergraduate business-related majors, who rated the applicants' suitability for 2 job positions and work shifts. Results: Findings indicated disparities in ratings of employability as a function of disability type. Paired comparisons yielded complementary findings, with effects of disability type and Disability Type × Job Complexity, but no effects of public contact. Conclusions: Stereotyping and discrimination in employment decisions apparently persist, more than 10 years after the ADA. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
59.
阐述了电接点压力表补水泵定压系统的一些应用问题 ,给出了电接点压力表定压点的上、下限计算公式 ,并提出了该系统补给水泵、补给水箱及安全阀的设计选型方法 相似文献
60.
Titanium Dioxide, TiO2, is a photocatalyst with a unique characteristic. A surface coated with TiO2 exhibits an extremely high affinity for water when exposed to UV light and the contact angle decreases nearly to zero. Inversely, the contact angle increases when the surface is shielded from UV. This superhydrophilic nature gives a self-cleaning effect to the coated surface and has already been applied to some construction materials, car coatings and so on. We applied this property to the enhancement of boiling heat transfer. An experiment involving the pool boiling of pure water has been performed to make clear the effect of high wettability on heat transfer characteristics. The heat transfer surface is a vertical copper cylinder of 17 mm in diameter and the measurement has been done at saturated temperature and in a steady state. Both TiO2-coated and non-coated surfaces were used for comparison. In the case of the TiO2-coated surface, it is exposed to UV light for a few hours before experiment and it is found that the maximum heat flux (CHF) is about two times larger than that of the uncoated surface. The temperature at minimum heat flux (MHF) for the superhydrophilic surface is higher by 100 K than that for the normal one. The superhydrophilic surface can be an ideal heat transfer surface. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献