全文获取类型
收费全文 | 25517篇 |
免费 | 2472篇 |
国内免费 | 990篇 |
专业分类
电工技术 | 2763篇 |
综合类 | 2925篇 |
化学工业 | 2151篇 |
金属工艺 | 530篇 |
机械仪表 | 761篇 |
建筑科学 | 7176篇 |
矿业工程 | 958篇 |
能源动力 | 967篇 |
轻工业 | 2303篇 |
水利工程 | 1807篇 |
石油天然气 | 1055篇 |
武器工业 | 76篇 |
无线电 | 1450篇 |
一般工业技术 | 1929篇 |
冶金工业 | 925篇 |
原子能技术 | 105篇 |
自动化技术 | 1098篇 |
出版年
2024年 | 123篇 |
2023年 | 345篇 |
2022年 | 654篇 |
2021年 | 757篇 |
2020年 | 827篇 |
2019年 | 741篇 |
2018年 | 744篇 |
2017年 | 850篇 |
2016年 | 898篇 |
2015年 | 968篇 |
2014年 | 1572篇 |
2013年 | 1451篇 |
2012年 | 1867篇 |
2011年 | 1994篇 |
2010年 | 1476篇 |
2009年 | 1589篇 |
2008年 | 1498篇 |
2007年 | 1819篇 |
2006年 | 1596篇 |
2005年 | 1297篇 |
2004年 | 1060篇 |
2003年 | 865篇 |
2002年 | 757篇 |
2001年 | 648篇 |
2000年 | 527篇 |
1999年 | 389篇 |
1998年 | 352篇 |
1997年 | 286篇 |
1996年 | 228篇 |
1995年 | 173篇 |
1994年 | 154篇 |
1993年 | 95篇 |
1992年 | 79篇 |
1991年 | 46篇 |
1990年 | 36篇 |
1989年 | 46篇 |
1988年 | 28篇 |
1987年 | 21篇 |
1986年 | 17篇 |
1985年 | 26篇 |
1984年 | 17篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 23篇 |
1979年 | 5篇 |
1957年 | 1篇 |
1956年 | 1篇 |
1955年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
The kinetics of changes in the bound water content in dietetic sucrose-free sponge cakes (DC) during storage was investigated. The effect of edible films of polymyxan, pectin, xanthan, and carboxymethylcellulose upon this kinetics was also investigated. The quantitative changes in both states of water (slightly bound water and strongly bound water) were registered by combined dynamic analysis (thermogravimetry analysis, TGA, and differential thermal analysis, DTA). The moisture changes in DC crumb were analyzed by drying out to constant mass. The rate constants were determined according the equation q = qoe-kt. The values of rate constants 'k', in day-1, concerning the different edible films were as follows: for crumb moisture is (8.00 ≤ k ≤ 12.47) × 10-3, for bound water is (3.07 ≤ kw ≤ 6.26) × 10-2, for slightly bound water is (4.22 ≤ k1 ≤ 8.49) × 10-2 and for strongly bound water is (2.02 ≤ k2 ≤ 5.62) × 10-2 as compared to 18.53 × 10-3, 7.16 × 10-2, 9.04 × 10-2, and 5.36 × 10-2 in the uncovered DC, respectively. The best water-retaining effect in respect to crumb moisture during storage was ascertained in the use of polymyxan and xanthan films. The lowest rate constant values for bound water and its two states were measured for DC covered with pectin. The relation between the kinetics of both bound water states during storage and ageing of the crumb of DC covered with different edible films and the crumb microstructure was represented. By means of scanning electron microscope was read the smallest change in crumb microstructure of pectin-covered DC on the sixth day of storage. 相似文献
3.
随着电容测量技术的迅速发展,电容传感器在非电量测量和自动检测中得到广泛应用,但它在使用过程中也存在一些问题,针对在使用电容传感器过程中存在的几个问题,从电容传感器的原理和工作过程两个方面进行了讨论,并提出行之有效的处理方法。 相似文献
4.
The saturation capacity of n-alkanes in CHA, AFX and ERI zeolites, that consist of cages separated by windows, decreases with increasing carbon number. The major aim of the present communication is to demonstrate the possibility of separating n-alkane mixtures relying on differences in saturation capacities. To investigate this possibility, Configurational-Bias Monte Carlo simulations for adsorption of C3–nC6, nC4–nC6, and nC5–nC6 mixtures in CHA, AFX and ERI were carried out for equimolar bulk fluid phase. These mixture simulations show that for operation at fluid phase fugacities below about 1 MPa, the adsorbed phase in equilibrium with the bulk vapor phase is predominantly the alkane with the longer chain length, i.e. nC6. However, for operation at pressures in excess of 1 MPa, the adsorbed phase in equilibrium with the bulk liquid phase is richer in the component with the smaller chain length. In some cases, the nC6 is practically excluded from the zeolite. 相似文献
5.
This paper evaluates the behavior and performance of laminated circular elastomeric bearings and compares them to those of square and rectangular bearings. The study included an experimental evaluation and a nationwide survey of state Department of Transportations on the use and performance of circular bearings and bearings in general in their states. The experimental investigation studied the bearings' behavior in compression, compression and rotation, and compression and shear. Results from this limited study showed that the three bearings have similar stress-strain behavior in compression and they are in agreement with the AASHTO LRFD guide stress–strain curves. In compression and rotation, the AASHTO LRFD substructure moments are slightly less than the measured values for circular bearings and rectangular bearings rotated about their strong axis for a compressive stress of 10.3?MPa (1.5?ksi) and slightly higher than those of rectangular bearings rotated about their weak axis. In compression and shear, the shear stiffness of circular and square bearings is in agreement with theoretical values within the range of design displacements. Results from the survey showed that many states are using circular bearings and more states would consider using them, however no maintenance or monitoring data were available on their short-term and long-term performance. 相似文献
6.
简要介绍了鞍钢现有人造富矿生产能力,分析了鞍钢生产1600万t/a生铁所需要的炉料数量、品种和质量,并提出了解决炉料缺口的方法和措施。 相似文献
7.
The eye movements of young and older adults were tracked as they read sentences varying in syntactic complexity. In Experiment 1, cleft object and object relative clause sentences were more difficult to process than cleft subject and subject relative clause sentences; however, older adults made many more regressions, resulting in increased regression path fixation times and total fixation times, than young adults while processing cleft object and object relative clause sentences. In Experiment 2, older adults experienced more difficulty than young adults while reading cleft and relative clause sentences with temporary syntactic ambiguities created by deleting the that complementizers. Regression analyses indicated that readers with smaller working memories need more regressions and longer fixation times to process cleft object and object relative clause sentences. These results suggest that age-associated declines in working memory do affect syntactic processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
本文总结了近年冶金炉渣氮酸盐容量的研究方法,氮在炉渣中存在形态与炉渣氧分压的关系,炉渣氮化物容量与温度及炉渣成分的关系,并给出设计钢液脱氮渣系的基本原则。 相似文献
9.
10.
把拍卖和市场理念引入到生产计划的求解过程中,结合多Agent理论,对大规模生产系统按生产单元建立分布式模型.各个生产单元看作相对独立核算的经济实体,其目标是实现自身利益最大化.当生产能力足够时,按照需求进行生产;当生产能力不足以完全满足需求时,紧缺生产资源的持有者按照单位能力获得最大收益的原则进行生产竞价与拍卖,实现了各个生产单元的分布式自主协商决策,并设计了求解算法.算例研究证明该方法的可操作性和求解的有效性. 相似文献