全文获取类型
收费全文 | 308530篇 |
免费 | 10829篇 |
国内免费 | 5178篇 |
专业分类
电工技术 | 10182篇 |
技术理论 | 2篇 |
综合类 | 4877篇 |
化学工业 | 44599篇 |
金属工艺 | 14308篇 |
机械仪表 | 11117篇 |
建筑科学 | 11060篇 |
矿业工程 | 2436篇 |
能源动力 | 8166篇 |
轻工业 | 29841篇 |
水利工程 | 3409篇 |
石油天然气 | 3883篇 |
武器工业 | 775篇 |
无线电 | 38856篇 |
一般工业技术 | 53858篇 |
冶金工业 | 52286篇 |
原子能技术 | 4779篇 |
自动化技术 | 30103篇 |
出版年
2022年 | 2578篇 |
2021年 | 4662篇 |
2020年 | 3328篇 |
2019年 | 3245篇 |
2018年 | 4558篇 |
2017年 | 4695篇 |
2016年 | 4838篇 |
2015年 | 5092篇 |
2014年 | 7096篇 |
2013年 | 15918篇 |
2012年 | 10841篇 |
2011年 | 13350篇 |
2010年 | 11351篇 |
2009年 | 11688篇 |
2008年 | 12191篇 |
2007年 | 12070篇 |
2006年 | 10865篇 |
2005年 | 9498篇 |
2004年 | 8424篇 |
2003年 | 7900篇 |
2002年 | 7854篇 |
2001年 | 7613篇 |
2000年 | 6764篇 |
1999年 | 7090篇 |
1998年 | 17004篇 |
1997年 | 11980篇 |
1996年 | 9312篇 |
1995年 | 7027篇 |
1994年 | 6147篇 |
1993年 | 5813篇 |
1992年 | 4126篇 |
1991年 | 4031篇 |
1990年 | 3626篇 |
1989年 | 3506篇 |
1988年 | 3425篇 |
1987年 | 2869篇 |
1986年 | 2837篇 |
1985年 | 3470篇 |
1984年 | 3104篇 |
1983年 | 2741篇 |
1982年 | 2549篇 |
1981年 | 2584篇 |
1980年 | 2443篇 |
1979年 | 2261篇 |
1978年 | 2227篇 |
1977年 | 2782篇 |
1976年 | 4157篇 |
1975年 | 1889篇 |
1974年 | 1776篇 |
1973年 | 1781篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Moustapha Moussa Amudhan Ponrajan Osvaldo H. Campanella Martin R. Okos Mario M. Martinez Bruce R. Hamaker 《International Journal of Food Science & Technology》2022,57(7):4594-4601
Traditional West African pearl millet couscous products are popular; however, their preparation is laborious, time-consuming and energy-demanding, involving agglomeration, steaming, drying and sieving steps. In this study, a process was developed to produce millet couscous using a high pressure, high temperature and low-cost single-screw extruder. The innovation was to directly process the cooked low-moisture extrudate to a couscous product by drying and milling to the appropriate particle size (ranging between 1 and 2 mm). Throughput for the traditional process as prepared for commercial sale is 50 kg per day, but with the same amount of labour, the extrusion process yields ~350 kg per day. A consumer sensory study held in Niamey (Niger) showed that the extruded millet couscous was comparable to traditional couscous, though this was dependent on selection of the proper millet variety. This novel extrusion process could stimulate small- to medium-scale manufacturing of couscous and couscous-type products in West Africa. 相似文献
32.
33.
34.
Catalysis Letters - A new zirconium based carbonaceous solid acid catalyst Zr@CC-PA with both Lewis and Bronsted acidic sites was prepared by simultaneous carbonization and phosphonation of glucose... 相似文献
35.
Fischer-Tropsch synthesis of the CO2 in biogas aims at producing light hydrocarbons and increasing its calorific value for feeding into the grid. Fe catalysts with Mn and K as promoters are supposed to yield high amounts of light hydrocarbons. Using a Fe-Mn-K/MgO catalyst, a parameter screening and long-term experiments were carried out. The catalyst shows, within the examined range, the highest selectivity to C2–C4 hydrocarbons at 450 °C, 8 bar(a), and a gas hourly space velocity of 350 h−1. Calcination of the catalyst resulted in a significant drop of activity and an almost complete loss of selectivity to hydrocarbons. Admixture of steam to the reactant gas lowers the tendency to carbon deposition but also promotes the water-gas shift reaction and results in lower yields of hydrocarbons. 相似文献
36.
Material encapsulation is a relatively new technique for coating a micro/nanosize particle or droplet with polymeric or inorganic shell. Encapsulation technology has many applications in various fields including drug delivery, cosmetic, agriculture, thermal energy storage, textile, and self-healing polymers. Poly(methyl methacrylate) (PMMA) is widely used as shell material in encapsulation due to its high chemical stability, biocompatibility, nontoxicity, and good mechanical properties. The main approach for micro/nanoencapsulation of materials using PMMA as shell comprises emulsion-based techniques such as emulsion polymerization and solvent evaporation from oil-in-water emulsion. In the present review, we first focus on the encapsulation techniques of liquid materials with PMMA shell by analyzing the effective processing parameters influencing the preparation of PMMA micro/nanocapsules. We then describe the morphology of PMMA capsules in emulsion systems according to thermodynamic relations. The techniques to investigation of mechanical properties of capsule shell and the release mechanisms of core material from PMMA capsules were also investigated. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48039. 相似文献
38.
Durmuş Burhanettin Temurtaş Hasan Özyön Serdar 《Neural computing & applications》2020,32(22):17097-17113
Neural Computing and Applications - This study presents the design of a tenth-order multiple feedback Chebyshev low-pass filter (MF-C-LPF). Component selection and gain calculation of filters are... 相似文献
39.
Wireless Personal Communications - The orthogonal frequency division multiplexing (OFDM) is the most encouraging multi-carrier modulation system chosen for the high data rates but the objective is... 相似文献
40.