全文获取类型
收费全文 | 1607篇 |
免费 | 33篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 11篇 |
综合类 | 1篇 |
化学工业 | 195篇 |
金属工艺 | 11篇 |
机械仪表 | 28篇 |
建筑科学 | 80篇 |
矿业工程 | 8篇 |
能源动力 | 33篇 |
轻工业 | 201篇 |
水利工程 | 16篇 |
石油天然气 | 3篇 |
无线电 | 126篇 |
一般工业技术 | 220篇 |
冶金工业 | 502篇 |
原子能技术 | 18篇 |
自动化技术 | 189篇 |
出版年
2023年 | 6篇 |
2022年 | 7篇 |
2021年 | 18篇 |
2020年 | 14篇 |
2019年 | 20篇 |
2018年 | 18篇 |
2017年 | 23篇 |
2016年 | 12篇 |
2015年 | 17篇 |
2014年 | 27篇 |
2013年 | 80篇 |
2012年 | 71篇 |
2011年 | 54篇 |
2010年 | 50篇 |
2009年 | 49篇 |
2008年 | 76篇 |
2007年 | 68篇 |
2006年 | 51篇 |
2005年 | 56篇 |
2004年 | 38篇 |
2003年 | 45篇 |
2002年 | 38篇 |
2001年 | 39篇 |
2000年 | 42篇 |
1999年 | 35篇 |
1998年 | 125篇 |
1997年 | 77篇 |
1996年 | 57篇 |
1995年 | 40篇 |
1994年 | 38篇 |
1993年 | 34篇 |
1992年 | 18篇 |
1991年 | 27篇 |
1990年 | 15篇 |
1989年 | 15篇 |
1988年 | 14篇 |
1987年 | 16篇 |
1986年 | 21篇 |
1985年 | 25篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 10篇 |
1978年 | 8篇 |
1977年 | 13篇 |
1976年 | 23篇 |
1975年 | 7篇 |
1974年 | 9篇 |
排序方式: 共有1642条查询结果,搜索用时 31 毫秒
131.
Darren McCarthy 《国外电子测量技术》2011,(9):5-8
在把无线电芯片或模块集成到典型的嵌入式系统中时,设计人员必须面临的一项常见任务是追踪和消除噪声和杂散信号。潜在的噪声来源包括:开关电源、来自系统其它部分的数字噪声、以及外部噪声来源。 相似文献
132.
Different melt mixing sequences were applied to incorporate multiwalled carbon nanotubes (CNTs) into blends prepared from high density polyethylene (PE) and polyamide 12 (PA). Electron microscopy, rheology and electrical resistivity were used to characterize the morphology and microstructure. At a composition of 75PA/25PE, presence of CNT at the interface promoted by premixing the CNTs in the PE phase, resulted in finer phase morphology and a decrease in the resistivity of up to five decades relative to other mixing procedures used. At a composition of 25PA/75PE, premixing the CNT in the PA phase resulted in their segregation inside and around the PA domains and a four decade lower resistivity. Interestingly, compounds that yielded the lowest resistivity were also characterized by increased low frequency melt storage modulus (G′) which indicates the existence of a correlation between the two properties. 相似文献
133.
Benjamin P. McCarthy Larry R. Pederson Ralph E. Williford Xiao-Dong Zhou 《Journal of the American Ceramic Society》2009,92(8):1672-1678
Intermediate-stage sintering of lanthanum strontium manganite (LSM, where Sr=0.00, 0.05, 0.10, 0.15, and 0.20) was shown in dilatometry studies to be accelerated when subjected to alternating flows of air and nitrogen. The extent of rate enhancement decreased with increased Sr content, and decreased with increased temperature, which coincides with diminished oxygen nonstoichiometry. Shrinkage rates were further shown to be sensitive to the difference in oxygen content in the alternating gas flows. Baseline air sintering rates were measured using stepwise isothermal dilatometry, from which kinetic parameters were calculated using the Makipirtti–Meng model. Activation energies for sintering in air were determined to be 255 ± 26, 258 ± 28, 308 ± 32, 373 ± 37, and 417 ± 41 kJ/mol for Sr=0.0, 0.05, 0.10, 0.15, and 0.20, respectively. A diffusion-based model is proposed that is consistent with trends in accelerated shrinkage versus temperature. Transient cation vacancy gradients, which lead to higher cation mobility, were calculated from established oxygen diffusivities and oxygen nonstoichiometry as a function of temperature and time. A potential application of this approach is the processing of LSM-based cathode-side contact pastes in solid oxide fuel cells. 相似文献
134.
135.
Deepak Shamvedi Oliver J. McCarthy Eoghan O’Donoghue Cyril Danilenkoff Paul O’Leary Ramesh Raghavendra 《Virtual and Physical Prototyping》2018,13(4):301-310
This research relates to the design, modelling and fabrication of 3D metal printed heat sinks. The heat sinks presented in the research are the commonly used longitudinal fin solid heat sink (LFSHS) and three LFSHS lattice structure designs, differing only in their lattice sizes, fabricated using the Direct Metal Laser Sintering (DMLS) technique in Maraging Steel (MS1), on an EOSINT M280 system. In order to increase the heat sink surface area, the heat sinks are manufactured with mesh lattices along the length of the fins, while keeping the overall heat sink volume constant. The research is focused on pushing the limitations of the DMLS technique for the development of repeating unit, lattice structures heat sinks, and to examine the effect of incrementally varying the lattice sizes with regards to the resultant surface area of the heat sink and the thermal performance of the system. The results obtained under natural convection show that the thermal performance of the LFSHS outperformed all lattice structure heat sinks. This is due to the fact that, the pressure drop across the lattice heat sinks were so high, due to lattice meshes that it negated the positive effect of the greater surface area. 相似文献
136.
SUMMARY A dielectric-constant-response radiofrequency detector for gas chromatography is described. The detector is extremely sensitive to organic vapors; it should display general response to compounds which have a dielectric constant different than the carrier gas. Limits of detection have been significantly decreased when compared to previously suggested designs for radio-frequency detectors. The detector is physically small and readily compatible with commercially available chromatographs. A theory for the signal response of the detector is proposed. 相似文献
137.
Ed Blakey 《Natural computing》2011,10(4):1245-1259
Unconventional computers—which may, for example, exploit chemical/analogue/quantum phenomena in order to compute, rather than
electronically implementing discrete logic gates—are widely studied in both theoretical and practical contexts. One particular
motivation behind unconventional computation is the desire efficiently to solve classically difficult problems—we recall chemical-computer
attempts at solving
NP
-complete problems such as the Travelling Salesperson Problem—, with computational complexity theory offering the criteria
for judging this efficiency. However, care must be taken here; conventional (Turing-machine-style) complexity analysis is
not always appropriate for unconventional computers: new, non-standard computational resources, with correspondingly new complexity
measures, are often required. Accordingly, we discuss in the present paper various resources beyond merely time and space
(and, indeed, discuss various interpretations of the term ‘resource’ itself), advocating such resources’ consideration when
analysing the complexity of unconventional computers. We hope that this acts as a useful starting point for practitioners
of unconventional computing and computational complexity. 相似文献
138.
139.
Ed Wehde 《Computer Fraud & Security》1999,1999(6):6
A pioneer of anti-spam software and E-mail programs has formed partnerships with a number of leading industry players to combat the growing problem of spam, or unsolicited E-mail. 相似文献
140.
Many embedded systems and consumer appliances require high performance at extremely low price points, and they need them yesterday! Meeting these needs is the latest challenge for system and processor architects. SandCraft recognized this challenge early on and developed the Montage architecture to meet these needs and generate revenue that fuels business growth. Montage implements MIPS-compatible processors for license to MIPS licensees. We have implemented two Montage incarnations now on the market: the SR1 and the SR1-GX high-performance microprocessor cores. Other designs are in the pipeline. With the intellectual property in place, the architecture will proliferate and show that low cost and flexibility do not have to come at the cost of compromising performance. Here, we describe the philosophy behind the development of the Montage architecture and illustrate some of the thinking that resulted in this processor line 相似文献