全文获取类型
收费全文 | 2072篇 |
免费 | 40篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 225篇 |
金属工艺 | 1087篇 |
机械仪表 | 18篇 |
建筑科学 | 13篇 |
矿业工程 | 1篇 |
能源动力 | 55篇 |
轻工业 | 80篇 |
水利工程 | 9篇 |
石油天然气 | 4篇 |
无线电 | 132篇 |
一般工业技术 | 239篇 |
冶金工业 | 104篇 |
自动化技术 | 135篇 |
出版年
2023年 | 11篇 |
2022年 | 15篇 |
2021年 | 24篇 |
2020年 | 17篇 |
2019年 | 26篇 |
2018年 | 44篇 |
2017年 | 31篇 |
2016年 | 35篇 |
2015年 | 20篇 |
2014年 | 39篇 |
2013年 | 98篇 |
2012年 | 91篇 |
2011年 | 119篇 |
2010年 | 121篇 |
2009年 | 134篇 |
2008年 | 138篇 |
2007年 | 124篇 |
2006年 | 81篇 |
2005年 | 78篇 |
2004年 | 87篇 |
2003年 | 128篇 |
2002年 | 107篇 |
2001年 | 80篇 |
2000年 | 47篇 |
1999年 | 43篇 |
1998年 | 56篇 |
1997年 | 19篇 |
1996年 | 24篇 |
1995年 | 23篇 |
1994年 | 62篇 |
1993年 | 33篇 |
1992年 | 16篇 |
1991年 | 23篇 |
1990年 | 8篇 |
1989年 | 14篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 12篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1977年 | 5篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1971年 | 4篇 |
排序方式: 共有2112条查询结果,搜索用时 15 毫秒
1.
M A Fennir J A Landry H S Ramaswamy V G S Raghavan 《The Journal of microwave power and electromagnetic energy》2003,38(3):189-196
This study investigates the effect of extraction methods on the color of date syrup and the potential use of microwave power for syrup processing. Sugar solutions were extracted from dates by boiling, soaking and blending. Color and sugar content of the extracted solutions were measured, and the percentage of sugar extracted form the total fruit sugar determined. Boiling was found to be the most efficient method of extraction whereby 74% of total samples sugar was extracted. In contrast, only 54.2% of fruit sugar was extracted by blending and 42% by soaking. In addition, solutions extracted by soaking and blending had a foaming problem in the subsequent concentration process. The extraction method had no effect on the product final color. The extracted solution was concentrated using two heating methods: conventional and microwave heating at a 600 W capacity and a frequency of 2450 MHz applied at three power levels: 10, 7, and 6. In the heating process, 180 minutes were needed to achieve a 77% degrees Brix using convective heating, while it took 81, 138, and 166 minutes of microwave heating at power level 10, 7, and 6, respectively to achieve the same concentration. Water activity of the syrup was measured within a sugar content range of 50 to 80% degrees Brix and the sugar concentration at which the product is shelf stable was determined at 76%. 相似文献
2.
3.
Kubat M. Hafez A. Raghavan V.V. Lekkala J.R. Wei Kian Chen 《Knowledge and Data Engineering, IEEE Transactions on》2003,15(6):1522-1534
Association mining techniques search for groups of frequently co-occurring items in a market-basket type of data and turn these groups into business-oriented rules. Previous research has focused predominantly on how to obtain exhaustive lists of such associations. However, users often prefer a quick response to targeted queries. For instance, they may want to learn about the buying habits of customers that frequently purchase cereals and fruits. To expedite the processing of such queries, we propose an approach that converts the market-basket database into an itemset tree. Experiments indicate that the targeted queries are answered in a time that is roughly linear in the number of market baskets, N. Also, the construction of the itemset tree has O(N) space and time requirements. Some useful theoretical properties are proven. 相似文献
4.
Eric P. Kvam Ph.D. Srikanth B. Samavedam B.Tech. 《JOM Journal of the Minerals, Metals and Materials Society》1994,46(3):47-51
The Ge-Si on Si epilayer system, besides being an interesting technological system in its own right, is a superb model for strained-layer studies. The point defect and symmetry defect structures associated with compound semiconductors can be avoided, allowing a focus on the mechanics of the system. Dislocation sources, glide behavior, and performance effects have been examined for strained-layer systems. Surprises have appeared along the way, but these materials are now becoming characterized well enough for industrial device applications. 相似文献
5.
6.
7.
8.
9.
The regular associated solution model for binary systems has been modified by incorporating the size of the complex as an
explicit variable. The thermodynamic properties of the liquid alloy and the interactions between theA
μB type of complex and the unassociated atoms in anA-B binary have been evaluated as a function of relative size of the complex using the activity coefficients at infinite dilution
and activity data at one other composition in the binary. The computational procedure adopted for determining the concentration
of clusters and interaction energies in the associated liquid is similar to that proposed by Lele and Rao. The analysis has
been applied to the thermodynamic mixing functions of liquid Al-Ca alloys believed to contain Al2Ca associates. It is found that the size of the cluster significantly affects the interaction energies between the complex
and the unassociated atoms, while the equilibrium constant and enthalpy change for the association reaction exhibit only minor
variation, when the equations are fitted to experimental data. The interaction energy between unassociated free atoms remains
virtually unaltered as the size of the complex is varied between extreme values. Accurate data on free energy, enthalpy, and
volume of mixing at the same temperature on alloy systems with compound forming tendency would permit a rigorous test of the
proposed model. 相似文献
10.