全文获取类型
收费全文 | 4964篇 |
免费 | 287篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 33篇 |
综合类 | 5篇 |
化学工业 | 1017篇 |
金属工艺 | 162篇 |
机械仪表 | 111篇 |
建筑科学 | 237篇 |
矿业工程 | 8篇 |
能源动力 | 151篇 |
轻工业 | 455篇 |
水利工程 | 47篇 |
石油天然气 | 40篇 |
武器工业 | 2篇 |
无线电 | 427篇 |
一般工业技术 | 952篇 |
冶金工业 | 839篇 |
原子能技术 | 41篇 |
自动化技术 | 737篇 |
出版年
2023年 | 40篇 |
2022年 | 68篇 |
2021年 | 135篇 |
2020年 | 101篇 |
2019年 | 117篇 |
2018年 | 147篇 |
2017年 | 139篇 |
2016年 | 166篇 |
2015年 | 120篇 |
2014年 | 162篇 |
2013年 | 285篇 |
2012年 | 284篇 |
2011年 | 349篇 |
2010年 | 249篇 |
2009年 | 266篇 |
2008年 | 303篇 |
2007年 | 290篇 |
2006年 | 231篇 |
2005年 | 242篇 |
2004年 | 177篇 |
2003年 | 152篇 |
2002年 | 157篇 |
2001年 | 76篇 |
2000年 | 72篇 |
1999年 | 60篇 |
1998年 | 62篇 |
1997年 | 59篇 |
1996年 | 69篇 |
1995年 | 51篇 |
1994年 | 53篇 |
1993年 | 54篇 |
1992年 | 41篇 |
1991年 | 27篇 |
1990年 | 41篇 |
1989年 | 40篇 |
1988年 | 34篇 |
1987年 | 45篇 |
1986年 | 40篇 |
1985年 | 35篇 |
1984年 | 28篇 |
1983年 | 30篇 |
1982年 | 29篇 |
1981年 | 16篇 |
1980年 | 15篇 |
1979年 | 14篇 |
1978年 | 16篇 |
1977年 | 10篇 |
1976年 | 11篇 |
1975年 | 11篇 |
1973年 | 7篇 |
排序方式: 共有5264条查询结果,搜索用时 187 毫秒
1.
Kevin J. Hanley 《International journal for numerical methods in engineering》2020,121(21):4865-4877
An algorithm is presented for discrete element method simulations of energy-conserving systems of frictionless, spherical particles in a reversed-time frame. This algorithm is verified, within the limits of round-off error, through implementation in the LAMMPS code. Mechanisms for energy dissipation such as interparticle friction, damping, rotational resistance, particle crushing, or bond breakage cannot be incorporated into this algorithm without causing time irreversibility. This theoretical development is applied to critical-state soil mechanics as an exemplar. It is shown that the convergence of soil samples, which differ only in terms of their initial void ratio, to the same critical state requires the presence of shear forces and frictional dissipation within the soil system. 相似文献
2.
Shank S. Kulkarni Kyoo Sil Choi Wenbin Kuang Nalini Menon Bernice Mills Ayoub Soulami Kevin Simmons 《International Journal of Hydrogen Energy》2021,46(36):19001-19022
The use of hydrogen as a fuel is increasing exponentially, and the most economical way to store and transport hydrogen for fuel use is as a high-pressure gas. Polymers are widely used for hydrogen distribution and storage systems because they are chemically inert towards hydrogen. However, when exposed to high-pressure hydrogen, some hydrogen diffuses through polymers and occupies the preexisting cavities inside the material. Upon depressurization, the hydrogen trapped inside polymer cavities can cause blistering or cracking by expanding these cavities. A continuum mechanics–based deformation model was deployed to predict the stress distribution and damage propagation while the polymer undergoes depressurization after high-pressure hydrogen exposure. The effects of cavity size, cavity location, and pressure inside the cavity on damage initiation and evolution inside the polymer were studied. The stress and damage evolution in the presence of multiple cavities was also studied, because interaction among cavities alters the damage and stress field. It was found that all these factors significantly change the stress state in the polymer, resulting in different paths for damage propagation. The effect of adding carbon black filler particles and plasticizer on the damage was also studied. It was found that damage tolerance of the polymer increases drastically with the addition of carbon black fillers, but decreases with the addition of the plasticizer. 相似文献
3.
Neil Maiden Kristine Pitts Kevin Pudney Konstantinos Zachos 《International journal of human-computer interaction》2019,35(7):605-619
There has been little research to investigate the impact of software to support the care for older people with dementia care. This article reports the evaluation of software adapted to support one key person-centered task for the care of older residents with dementia – recording and sharing daily care notes. The evaluation on the dementia wing of 1 residential home for over 6 months revealed that use of the software on mobile devices carried by the carers increased the number and volume of daily care notes recorded, but only for the types of content that were already being recorded by carers. Carers reported more advantages that resulted from daily care notes once in digital form than from the documenting task, as well as barriers to the use of mobile digital software to record daily care notes. 相似文献
4.
Golovin V. A. Pechnikov N. V. Shchelkov V. A. Tsivadze A. Yu. 《Protection of Metals and Physical Chemistry of Surfaces》2018,54(6):1221-1232
Protection of Metals and Physical Chemistry of Surfaces - The possibility is shown of creating a chart of local corrosion damage in the walls of heat-exchange tubes on the basis of the data of... 相似文献
5.
Differences between oculomotor and perceptual artifacts for temporally limited head mounted displays
Alexander Goettker Kevin J. MacKenzie T. Scott Murdison 《Journal of the Society for Information Display》2020,28(6):509-519
We used perceptual and oculomotor measures to understand the negative impacts of low (phantom array) and high (motion blur) duty cycles with a high‐speed, AR‐likehead‐mounted display prototype. We observed large intersubject variability for the detection of phantom array artifacts but a highly consistent and systematic effect on saccadic eye movement targeting during low duty cycle presentations. This adverse effect on saccade endpoints was also related to an increased error rate in a perceptual discrimination task, showing a direct effect of display duty cycle on the perceptual quality. For high duty cycles, the probability of detecting motion blur increased during head movements, and this effect was elevated at lower refresh rates. We did not find an impact of the temporal display characteristics on compensatory eye movements during head motion (e.g., VOR). Together, our results allow us to quantify the tradeoff of different negative spatiotemporal impacts of user movements and make subsequent recommendations for optimized temporal HMD parameters. 相似文献
6.
7.
Yu. I. Golovin D. V. Lopatin R. K. Nikolaev A. V. Umrikhin 《Technical Physics Letters》2004,30(5):426-428
The effect of crystal orientation on the photogeneration of free charge carriers was studied for C60 single crystals in a weak magnetic field. The photoconductivity sharply depends on the orientation of magnetic field with
respect to the crystallographic directions, showing a 5–8% increase for seven axes of the C60 crystal. 相似文献
8.
The phenomenon of thermally induced distortions in unsymmetrical laminates is well understood, and it may be shown that a square, unsymmetrical 0.90 laminate will tend to form two stable geometries with a snap-through phenomenon between them. This paper discusses laminates in which at each point the lay-up is symmetrical across the laminate mid-plane, but which still exhibit multiple stable geometries. The number of stable geometries can be controlled by the details of the lay-up from the minimum of two to, in principle, an unlimited number. In addition it will be shown how a similar process can be used to generate multiple stable stress states and geometries in unidirectional laminates. This paper represents a very preliminary experimental investigation of the design space available for such composite laminates. Possible applications of composites with multiple stable geometries are noted. 相似文献
9.
10.
Chih-Wea Wang Chi-Feng Wu Jin-Fu Li Cheng-Wen Wu Tony Teng Kevin Chiu Hsiao-Ping Lin 《Journal of Electronic Testing》2002,18(6):637-647
In this paper we propose a novel built-in self-test (BIST) design for embedded SRAM cores. Our contribution includes a compact and efficient BIST circuit with diagnosis support and an automatic diagnostic system. The diagnosis module of our BIST circuit can capture the error syndromes as well as fault locations for the purposes of repair and fault/failure analysis. In addition, our design provides programmability for custom March algorithms with lower hardware cost. The combination of the on-line programming mode and diagnostic system dramatically reduces the effort in design debugging and yield enhancement. We have designed and implemented test chips with our BIST design. Experimental results show that the area overhead of the proposed BIST design is only 2.4% for a 128 KB SRAM, and 0.65% for a 2 MB one. 相似文献