全文获取类型
收费全文 | 3208篇 |
免费 | 314篇 |
国内免费 | 198篇 |
专业分类
电工技术 | 119篇 |
综合类 | 291篇 |
化学工业 | 349篇 |
金属工艺 | 328篇 |
机械仪表 | 304篇 |
建筑科学 | 215篇 |
矿业工程 | 471篇 |
能源动力 | 27篇 |
轻工业 | 222篇 |
水利工程 | 40篇 |
石油天然气 | 82篇 |
武器工业 | 28篇 |
无线电 | 277篇 |
一般工业技术 | 345篇 |
冶金工业 | 221篇 |
原子能技术 | 25篇 |
自动化技术 | 376篇 |
出版年
2024年 | 15篇 |
2023年 | 42篇 |
2022年 | 79篇 |
2021年 | 107篇 |
2020年 | 89篇 |
2019年 | 80篇 |
2018年 | 62篇 |
2017年 | 106篇 |
2016年 | 104篇 |
2015年 | 97篇 |
2014年 | 176篇 |
2013年 | 189篇 |
2012年 | 241篇 |
2011年 | 214篇 |
2010年 | 177篇 |
2009年 | 195篇 |
2008年 | 158篇 |
2007年 | 210篇 |
2006年 | 226篇 |
2005年 | 173篇 |
2004年 | 164篇 |
2003年 | 145篇 |
2002年 | 116篇 |
2001年 | 108篇 |
2000年 | 112篇 |
1999年 | 60篇 |
1998年 | 68篇 |
1997年 | 48篇 |
1996年 | 29篇 |
1995年 | 38篇 |
1994年 | 20篇 |
1993年 | 21篇 |
1992年 | 12篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1982年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有3720条查询结果,搜索用时 5 毫秒
1.
Hasrul Abdi Hasibuan Azis Boing Sitanggang Nuri Andarwulan Purwiyatno Hariyadi 《International Journal of Food Science & Technology》2021,56(9):4549-4558
This research aimed to produce triacylglycerols fraction rich in palmitic acid (PA) at the sn-2 position from hard palm stearin (HPS) through acetone fractionation. Fractionations were done at HPS-to-acetone ratios of 1:3, 1:5 and 1:7 (w/v) and at temperatures of 25, 30 and 35 °C for 3 h. Triacylglycerols with PA at the sn-2 position, such as tripalmitoylglycerol (PPP) and dipalmitoyl-stearoyl-glycerol (PPS), were concentrated in the solid fraction, obtained after separation by filtration. The optimal fractionation conditions were at a HPS-to-acetone ratio of 1:5 (w/v) and 30 °C. The total PPP and PPS content was more than 91%, with a corresponding yield of more than 59%. Triacylglycerols obtained were composed of more than 91% PA in which 88% were at the sn-2 position. Conclusively, the solvent fractionation is a suited alternative method for the preparation of triacylglycerols used for the enzymatic synthesis of 1,3-dioleoyl-2-palmitoylglycerol which is the main triacylglycerol for human milk fat substitute. 相似文献
2.
3.
4.
Ratnabali Biswas Kaushik Chowdhury Dharma P. Agrawal 《International Journal of Wireless Information Networks》2006,13(4):303-315
Wireless sensor network is an emerging technology that enables remote monitoring of large geographical regions. In this paper, we address the problem of distributing attributes over such a large-scale sensor network so that the cost of data retrieval is minimized. The proposed scheme is a data-centric storage scheme where the attributes are distributed over the network depending on the correlations between them. The problem addressed here is similar to the Allocation Problem of distributed databases. In this paper, we have defined the Allocation Problem in the context of sensor networks and have proposed a scheme for finding a good distribution of attributes to the sensor network. We also propose an architecture for query processing given such a distribution of attributes. We analytically determine the conditions under which the proposed architecture is beneficial and present simulation results to demonstrate the same. To the best of our knowledge, this is the first attempt to determine an allocation of attributes over a sensor network based on the correlations between attributes. 相似文献
5.
6.
本文通过大量的单因素和多因素试验,确定了新型耐嚼糖果的制造工艺参数,研制出一种咀嚼时间长,口感类似胶姆糖,有较好的粘弹性和硬度,可被人体完全消化代谢的新型糖果。 相似文献
7.
Effects of storage period on hydroxymethylfurfural, pH and colour were studied in white hard grape pekmez (Zile pekmezi), a Turkish traditional product. Pekmez samples were stored at 20 °C for 8 months. Analysis of variance revealed significant differences in hydroxymethylfurfural, pH, L, a and b values (P<0.01) based on storage time. 相似文献
8.
Sucrose crystallization in thin films (50–55 μm) was studied, using a videomicroscopy technique, at conditions encountered during hard panning processes. No nucleation occurred in unseeded films, while a linear increase in seeded crystals occurred during drying. Crystal growth rate increased with temperature (25–30°C) and with air velocity (2.4–12.5 m/sec), but did not change with varying sucrose concentrations (70–76% w/w) and relative humidities (0–66% at 30°C). FD & C Yellow No. 5 food coloring in the dye form (0.05–0.5 g/100 mL) showed no effects while similar concentrations in the lake form inhibited crystal growth rate. 相似文献
9.
Investigations have been carried out on an erosion-corrosion apparatus to investigate the behaviour of corrosion-resistant highalloy iron-base materials containing hard phases. These materials had been optimized for increased wear resistance under complex stress conditions. As expected, in dry erosion tests, very low mass losses were established; there was little difference between the materials. Also, in corrosive environments (NaCl, H2SO4), the materials showed good stability; however, the duplex structures were superior to the martensitic ones. The combination of erosion and corrosion produced large differences and, in some cases, markedly reduced resistance to damage. These results confirmed observations that it is impossible to deduce the environmentally influenced mechanical behaviour of an alloy from its behaviour in separate corrosion and erosion experiments. The basic mechanisms underlying these processes have been investigated only tentatively. 相似文献
10.
主要针对核桃软糖在气温稍高、湿度较大的环境中容易粘结,造成质量下降和贮藏期缩短的现象,通过改进配方和工艺,防止和延缓核桃软糖粘结,延长了产品的贮藏时间。 相似文献