全文获取类型
收费全文 | 45889篇 |
免费 | 2126篇 |
国内免费 | 649篇 |
专业分类
电工技术 | 1155篇 |
技术理论 | 1篇 |
综合类 | 835篇 |
化学工业 | 8798篇 |
金属工艺 | 1695篇 |
机械仪表 | 1358篇 |
建筑科学 | 2746篇 |
矿业工程 | 588篇 |
能源动力 | 1423篇 |
轻工业 | 3587篇 |
水利工程 | 567篇 |
石油天然气 | 960篇 |
武器工业 | 93篇 |
无线电 | 3800篇 |
一般工业技术 | 6787篇 |
冶金工业 | 7416篇 |
原子能技术 | 484篇 |
自动化技术 | 6371篇 |
出版年
2023年 | 323篇 |
2022年 | 476篇 |
2021年 | 874篇 |
2020年 | 693篇 |
2019年 | 721篇 |
2018年 | 891篇 |
2017年 | 924篇 |
2016年 | 893篇 |
2015年 | 944篇 |
2014年 | 1358篇 |
2013年 | 2814篇 |
2012年 | 2026篇 |
2011年 | 2395篇 |
2010年 | 1882篇 |
2009年 | 1964篇 |
2008年 | 2143篇 |
2007年 | 2185篇 |
2006年 | 1950篇 |
2005年 | 1772篇 |
2004年 | 1450篇 |
2003年 | 1480篇 |
2002年 | 1474篇 |
2001年 | 1019篇 |
2000年 | 974篇 |
1999年 | 934篇 |
1998年 | 932篇 |
1997年 | 811篇 |
1996年 | 905篇 |
1995年 | 757篇 |
1994年 | 701篇 |
1993年 | 659篇 |
1992年 | 580篇 |
1991年 | 402篇 |
1990年 | 503篇 |
1989年 | 468篇 |
1988年 | 412篇 |
1987年 | 450篇 |
1986年 | 401篇 |
1985年 | 527篇 |
1984年 | 502篇 |
1983年 | 452篇 |
1982年 | 471篇 |
1981年 | 449篇 |
1980年 | 358篇 |
1979年 | 368篇 |
1978年 | 329篇 |
1977年 | 307篇 |
1976年 | 269篇 |
1975年 | 318篇 |
1973年 | 281篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
John C. Hart Gordon W. Lescinsky Daniel J. Sandin Thomas A. DeFanti Louis H. Kauffman 《The Visual computer》1993,9(7):346-355
The pipelined architecture and parallel organization of the AT&T Pixel Machine image computer are described and demonstrated with applications for the visualization of multidimensional fractals, particularly linear fractals and quaternion/ stacked Julia sets. Techniques for pushing the Pixel Machine to its peak abilities are described and apply to more recent parallel image computers as well. 相似文献
62.
For users of an executive information system (EIS), the EIS interface is the system and is crucial to the EIS's success. These guidelines for designing EIS interfaces are based on studies of actual EIS interfaces that meet the unique information needs of executives. 相似文献
63.
PS,LS和煤油体系的界面张力 总被引:3,自引:0,他引:3
本文以石油磺酸盐(PS)、木质素磺酸盐(LS)和煤油体系为对象,研究了PS/LS比、盐度、醇、Na_2SiO_3及聚合物对体系界面张力(IFT)的影响,探讨了PS与各组分间的相互作用,结果发现,在一定盐度和混合醇(正丁醇+异丙醇)浓度下,PS/LS>0.3/0.7时,体系可形成中相微乳液,IFT值达1×10~(-3)mN/m左右;LS和聚合物的存在使IFT升高;在表面活性剂驱油体系中,可用廉价的LS部分代替PS。 相似文献
64.
将薄膜电容真空计的测量室接于被测密闭容器,静态真空室接于一个比较容器,即组成一台压差式漏率测试仪。首先使两容器压力平衡,真空计读数为零。当被测容器存在漏孔时,真空计薄膜两侧形成压差,真空计指示读数,继而计算出该容器的漏率。应用商品真空计在抽真空测试时,检测的最小可测漏率达10-4~10-5Pa·L/s;而在充压测试时,因受气体温度变化的影响,灵敏度会降低几个量级。该仪器有可能具备寻找漏孔位置和确定漏孔漏率的功能。 相似文献
65.
66.
67.
John Bensted 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1985,35(4):181-184
Characterisation of raw materials for Portland cement manufacture by use of the methylene blue adsorption method is discussed. The method is shown to be a simple, convenient ‘rule of thumb’ procedure. It provides a guide to the quantity and type of argillaceous minerals present in a given raw material sample. 相似文献
68.
Experiments showing the frequency and amplitude of the flow induced motion of the gate for a 2- and a 4-in. swing check valve have been performed. The gate motion is due to turbulence in approach flow. We have found the dominant turbulent frequency of the approach flow is about half the natural frequency of the valves. The valves appear to be almost critically damped. Because of this, the valves respond almost as they would to a static force of the magnitude characteristic of the turbulent fluctuation in the flow. Both the dimensionless exciting force and the damping ratio have been found to be independent of valve size so the above statements are true for larger valves also. The recommended valve oscillation amplitudes and frequencies are used to calculate the wear at the shaft and at the stop. For an unpegged check valve, such as one of the 10-in. valves which was used at the San Onofre Nuclear Generation Station, it was found that shaft bearing wear would amount to 0.27 in.3/year and stop wear to 0.03 in.3/year. 相似文献
69.
Kosslyn Stephen M.; Koenig Olivier; Barrett Anna; Cave Carolyn Backer; Tang Joyce; Gabrieli John D. E. 《Canadian Metallurgical Quarterly》1989,15(4):723
Analyses of human object recognition abilities led to the hypothesis that 2 kinds of spatial relation representations are used in human vision. Evidence for the distinction between abstract categorical spatial relation representations and specific coordinate spatial relation representations was provided in 4 experiments. These results indicate that Ss make categorical judgments—on/off, left/right, and above/below—faster when stimuli are initially presented to the left cerebral hemisphere, whereas they make evaluations of distance—in relation to 2 mm, 3 mm, or 1 in. (2.54 cm)—faster when stimuli are initially presented to the right cerebral hemisphere. In addition, there was evidence that categorical representations developed with practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
70.