全文获取类型
收费全文 | 4289篇 |
免费 | 217篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 56篇 |
综合类 | 3篇 |
化学工业 | 1192篇 |
金属工艺 | 68篇 |
机械仪表 | 112篇 |
建筑科学 | 206篇 |
矿业工程 | 4篇 |
能源动力 | 165篇 |
轻工业 | 619篇 |
水利工程 | 44篇 |
石油天然气 | 46篇 |
无线电 | 299篇 |
一般工业技术 | 620篇 |
冶金工业 | 234篇 |
原子能技术 | 18篇 |
自动化技术 | 829篇 |
出版年
2024年 | 12篇 |
2023年 | 46篇 |
2022年 | 130篇 |
2021年 | 193篇 |
2020年 | 114篇 |
2019年 | 146篇 |
2018年 | 155篇 |
2017年 | 133篇 |
2016年 | 203篇 |
2015年 | 103篇 |
2014年 | 190篇 |
2013年 | 349篇 |
2012年 | 283篇 |
2011年 | 342篇 |
2010年 | 258篇 |
2009年 | 265篇 |
2008年 | 238篇 |
2007年 | 188篇 |
2006年 | 137篇 |
2005年 | 104篇 |
2004年 | 110篇 |
2003年 | 85篇 |
2002年 | 87篇 |
2001年 | 54篇 |
2000年 | 44篇 |
1999年 | 49篇 |
1998年 | 62篇 |
1997年 | 66篇 |
1996年 | 45篇 |
1995年 | 46篇 |
1994年 | 35篇 |
1993年 | 27篇 |
1992年 | 33篇 |
1991年 | 14篇 |
1990年 | 18篇 |
1989年 | 21篇 |
1988年 | 26篇 |
1987年 | 10篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 10篇 |
1983年 | 10篇 |
1982年 | 4篇 |
1981年 | 12篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 8篇 |
1976年 | 8篇 |
1975年 | 3篇 |
排序方式: 共有4515条查询结果,搜索用时 0 毫秒
1.
IR与RS-232的匹配技术 总被引:2,自引:0,他引:2
TedSalazar 《电子设计应用》2004,(3):86-87
现代电子设备通常包含最新的数据通信接口,以实现更高的数据率或增进用户的便利性。红外技术(IR)是数据通信接口的一个很好例子,但有时单独使用这种最新接口还是不够的,设备还需要与采用传统接口如RS-232的老设备兼容才会被用户所接受。因此,常见的红外技术和RS-232共存于同一设备中。 相似文献
2.
A fundamental problem for regulatory networks is to understand the relation between form and function: to uncover the underlying design principles of the network. Circadian clocks present a particularly interesting instance, as recent work has shown that they have complex structures involving multiple interconnected feedback loops with both positive and negative feedback. While several authors have speculated on the reasons for this, a convincing explanation is still lacking.We analyse both the flexibility of clock networks and the relationships between various desirable properties such as robust entrainment, temperature compensation, and stability to environmental variations and parameter fluctuations. We use this to argue that the complexity provides the flexibility necessary to simultaneously attain multiple key properties of circadian clocks. As part of our analysis we show how to quantify the key evolutionary aims using infinitesimal response curves, a tool that we believe will be of general utility in the analysis of regulatory networks. Our results suggest that regulatory and signalling networks might be much less flexible and of lower dimension than their apparent complexity would suggest. 相似文献
3.
Fernando J. Muzzio Marcos Llusa Christopher L. Goodridge Nhat-Hang Duong Elizabeth Shen 《Powder Technology》2008,186(3):247-254
This paper investigates the effects of processing and equipment parameters of a ribbon blender (i.e. loading method of lubricant, fill level, blade speed and blade design) on magnesium stearate homogeneity. A core sampling technique is used to obtain at least one hundred samples per sampling event, which are extracted throughout the blender and yield a thorough characterization of the entire bed. The results presented here can be used as a guideline to develop appropriate blending processes and characterization protocols for ribbon blenders. 相似文献
4.
5.
6.
Fernando J Beltrn F Javier Rivas Olga Gimeno 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(9):973-984
Photocatalytic ozonation (1O3 + VUV + TiO2), ozonation (O3), catalytic ozonation (O3 + TiO2), ozone photolysis (O3 + VUV), photocatalysis (TiO2 + VUV) and photolysis (VUV) have been compared in terms of formation of intermediates, extent of, mineralization (TOC, COD, chloride, nitrate) and kinetics in the aqueous treatment of three phenols (phenol, p‐chlorophenol and p‐nitrophenol). In all cases, photocatalytic ozonation led to lower degradation times for chemical oxygen demand and total organic carbon removal. Intermediates formed were similar in the different oxidation systems with some exceptions. They can be classified into three different types: polyphenols (resorcinol, catechol, hydroquinone), unsaturated carboxylic acids (maleic and fumaric acids) and saturated carboxylic acids (glyoxylic, formic and oxalic acids). First order kinetic equations have been checked for the oxidation processes studied in the case of the parent compound. Rate constants of these systems have also been calculated. Copyright © 2005 Society of Chemical Industry 相似文献
7.
8.
Alexander Pavlov Gonzalo D Garcia De Fernando Juan A Ordoez Lorenzo Hoz 《Journal of the science of food and agriculture》1994,64(2):141-143
The β-hydroxyacyl-CoA-dehydrogenase (HADH) activity of unfrozen and thawed frog legs was investigated. The enzyme was extracted by either immersing frog legs in phosphate buffer 0.1 M, pH 6.0 at 25°C for 15 min or pressing them between trichinoscopy glasses. The enzyme activity was assayed using acetoacetyl-CoA as substrate and measured spectrophotometrically at 340 nm. It was possible by both extraction methods to distinguish between thawed and unfrozen samples although when the juice was obtained by pressing the HADH activity of the dilution was ~ 1.5 times higher than that obtained by immersion. The HADH activity was significantly higher (P≤0·001) in frozen-thawed frogs than in unfrozen legs because during freezing there is a release of HADH. No significative differences were found in the HADH activity in samples frozen in the temperature range -10 to -196°C. HADH activity was not affected by the storage time in crushed ice up to 6 days. 相似文献
9.
Krick R.F. Clark L.T. Deleganes D.J. Wong K.L. Fernando R. Debnath G. Banik J. 《Solid-State Circuits, IEEE Journal of》1994,29(12):1455-1463
An implementation of the Pentium microprocessor architecture in 0.6 μm BiCMOS technology is described. Power dissipation is reduced and performance is enhanced over the previous generation. Processor features, implementation technology, and circuit techniques are discussed. An internal clock rate of 150 MHz is achieved at 3.7 V and -55°C 相似文献
10.
F. A. Calvo J. M. Guilemany J. M. Gomez de Salazar A. Urena 《Metallurgical and Materials Transactions B》1988,19(1):165-170
The present work studies the surface evolution of cinnabar, when it is leached with HBr acid for different conditions. The
dynamicin situ test has been studied by scanning electron microscopy and EDS techniques. According to the acid condition, time, and temperature,
the HgS presents different mechanisms of dissolution, and the results prove that the cinnabar does not present “memory effect”,
as proposed by other authors.16 相似文献