全文获取类型
收费全文 | 2451篇 |
免费 | 99篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 28篇 |
综合类 | 9篇 |
化学工业 | 556篇 |
金属工艺 | 92篇 |
机械仪表 | 97篇 |
建筑科学 | 43篇 |
矿业工程 | 9篇 |
能源动力 | 176篇 |
轻工业 | 271篇 |
水利工程 | 13篇 |
石油天然气 | 2篇 |
无线电 | 171篇 |
一般工业技术 | 533篇 |
冶金工业 | 203篇 |
原子能技术 | 15篇 |
自动化技术 | 340篇 |
出版年
2024年 | 12篇 |
2023年 | 43篇 |
2022年 | 106篇 |
2021年 | 109篇 |
2020年 | 88篇 |
2019年 | 100篇 |
2018年 | 110篇 |
2017年 | 107篇 |
2016年 | 111篇 |
2015年 | 52篇 |
2014年 | 107篇 |
2013年 | 201篇 |
2012年 | 117篇 |
2011年 | 151篇 |
2010年 | 122篇 |
2009年 | 98篇 |
2008年 | 95篇 |
2007年 | 92篇 |
2006年 | 58篇 |
2005年 | 58篇 |
2004年 | 35篇 |
2003年 | 44篇 |
2002年 | 45篇 |
2001年 | 28篇 |
2000年 | 26篇 |
1999年 | 30篇 |
1998年 | 39篇 |
1997年 | 35篇 |
1996年 | 35篇 |
1995年 | 19篇 |
1994年 | 19篇 |
1993年 | 20篇 |
1992年 | 13篇 |
1991年 | 19篇 |
1990年 | 18篇 |
1989年 | 19篇 |
1988年 | 19篇 |
1987年 | 19篇 |
1986年 | 15篇 |
1985年 | 13篇 |
1984年 | 10篇 |
1983年 | 10篇 |
1982年 | 6篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1978年 | 6篇 |
1976年 | 15篇 |
1974年 | 8篇 |
1973年 | 9篇 |
排序方式: 共有2558条查询结果,搜索用时 0 毫秒
1.
Catalysis Letters - An environmentally benign process for synthesizing 4-methoxyphenol through methylation of hydroquinone using polystyrene immobilized Bronsted acidic ionic liquid is presented.... 相似文献
2.
3.
Chattopadhyay Arup Kumar Nag Amitava Singh Jyoti Prakash 《Multimedia Tools and Applications》2022,81(24):34969-34999
Multimedia Tools and Applications - A secret sharing scheme partitions a secret into a set of shares and distributes them among the eligible participants, with each participant receiving one share... 相似文献
4.
Wireless Personal Communications - In this paper, cooperative communication (CC) assisted cognitive wireless sensor network (CWSN) is presented for monitoring health and activity of an end-user in... 相似文献
5.
6.
Nilesh P. Vanikar Shantipal S. Ohol Saeede Goldar 《International Journal of Cast Metals Research》2018,31(4):249-259
Bottom pour ladles with stopper rod systems are commonly used in the metal casting industry. However, stopper rod bottom-pouring systems have not yet been developed for the lower thermal masses of alloys typically used in the investment casting industry. Large thermal masses used with bottom pour systems are typically limited for ladles larger than 700 kg and to certain alloys with higher fluidity and longer solidification time like cast iron, aluminum alloys etc. In this study, bottom pour ladle designs and low thermal mass refractory systems have been developed and evaluated in production investment foundry trials with 300 kg pouring ladle. The ladles system and pouring practices used will be described along with the results from the pouring trials for SS304 that represents typical alloys used in Investment casting industries. Optimization of the variables used in an experimentation using Genetic algorithm is also explained. 相似文献
7.
This paper presents the design criteria, procedure, and implementation of a soft-switched power-factor-correction (PFC) circuit based on the extended-period quasi-resonant (EPQR) principles. All power electronic devices including switches and diodes in the circuit are fully soft switched. The design method is demonstrated in a prototype circuit. The operating principles are confirmed with computer simulation and experimental results. A comparison of the EP-QR operation and zero-voltage-transition (ZVT) pulse-width modulation (PWM) method 相似文献
8.
U. Rambabu N. R. Munirathnam T. L. Prakash B. Vengalrao S. Buddhudu 《Journal of Materials Science》2007,42(22):9262-9266
High purity gallium oxide nanopowders have been synthesized by using a simple precipitation technique with calcination at
elevated temperature. From the X-ray pattern, the phase purity of the synthesized powders was confirmed as β-Ga2O3. Elemental quantification (stoichiometry) of Ga2O3 was also examined from the X-ray energy dispersive analysis (EDAX). Based on the recorded Fourier Transform Infrared (FTIR)
spectrum of Ga2O3, the IR bands due to Ga–O bond and crystal lattice vibrations have been identified in the wavenumber range 400–4,000 cm−1. From the measured SEM images, it is obvious to notice that the pH value has been playing a dominant role in obtaining morphologically
different gallium oxide nanopowders. Thermogravimetric analysis reveals 8.3% of weight loss when the sample was heated to
the temperature of 1,100 °C from the room temperature, which also shows a crystalline phase transformation. It is very interesting
to report that a broad blue emission at 455 nm has been measured from the synthesized gallium oxide nanopowders. 相似文献
9.
Ann Barrett Anuradha Prakash Deborah Sakelakos Irwin Taub Samuel Cohen Yuki Ohashi 《Food Hydrocolloids》1998,12(4):401-408
The effects of composition and thermal treatment on the water sorption and diffusional properties of idealized protein gels arranged in bilayer configurations were determined; these water binding/migration properties were related to the mechanical characteristics of the gels. Samples were prepared from whey protein concentrate (WPC), they consisted of water:WPC ratios of 1.5 to 5.67, and were thermally set for 20–60 min. Moisture migration rates from samples interfaced with filters were determined, as were moisture sorption capacities of samples immersed in water. The physical properties of the gels were assessed by uniaxial compression and microscopy. Results showed that gel strength and consequent extent of protein interaction—as affected by thermal treatment—controlled the ability of the gel structure to absorb water. Sorption was exponentially correlated with gel modulus and linearly correlated with a function of protein content, heating time, and immersion time. Rates of diffusion from interfaced gels were dependent solely on water content. It was concluded that the degree of protein interaction, whether influenced by concentration or thermal treatment, affected network extensibility and thus the capacity of the gels to act as receptors of moisture. Results have implications for the functionality of shelf-stable sandwiches and other multicomponent foods. 相似文献
10.