全文获取类型
收费全文 | 1566篇 |
免费 | 173篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 15篇 |
综合类 | 2篇 |
化学工业 | 463篇 |
金属工艺 | 15篇 |
机械仪表 | 39篇 |
建筑科学 | 58篇 |
矿业工程 | 2篇 |
能源动力 | 72篇 |
轻工业 | 274篇 |
水利工程 | 20篇 |
石油天然气 | 6篇 |
无线电 | 100篇 |
一般工业技术 | 214篇 |
冶金工业 | 97篇 |
原子能技术 | 4篇 |
自动化技术 | 362篇 |
出版年
2024年 | 8篇 |
2023年 | 25篇 |
2022年 | 65篇 |
2021年 | 107篇 |
2020年 | 65篇 |
2019年 | 78篇 |
2018年 | 88篇 |
2017年 | 88篇 |
2016年 | 110篇 |
2015年 | 65篇 |
2014年 | 88篇 |
2013年 | 139篇 |
2012年 | 107篇 |
2011年 | 145篇 |
2010年 | 73篇 |
2009年 | 71篇 |
2008年 | 74篇 |
2007年 | 63篇 |
2006年 | 54篇 |
2005年 | 36篇 |
2004年 | 27篇 |
2003年 | 21篇 |
2002年 | 31篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 12篇 |
1998年 | 17篇 |
1997年 | 11篇 |
1996年 | 13篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1985年 | 6篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有1743条查询结果,搜索用时 828 毫秒
71.
72.
Mangili Patrick V. Junqueira Pedro G. Santos Lizandro S. Prata Diego M. 《Clean Technologies and Environmental Policy》2019,21(5):1073-1090
Clean Technologies and Environmental Policy - Maleic anhydride may be obtained from different technological routes, being the selective oxidation of benzene and oxidation of butane the only ones... 相似文献
73.
74.
Russian Engineering Research - Work standardization at Russian high-tech enterprises is considered, in the digital era. The new possibilities created by the digital economy permit increased... 相似文献
75.
Tamara G. Oberti Diego Larsen M. Susana Cortizo 《Polymer-Plastics Technology and Engineering》2019,58(4):443-453
New copolymers of dioctyl fumarate (DOF) and styrene (S) were synthetized by radical polymerization and used to modify bitumen. The poly(dioctyl fumarate-co-styrene) copolymers, PFS, were characterized by 1H-NMR and FTIR spectroscopies and size exclusion chromatography (SEC) in order to determine their monomer composition and weight average molecular weights, respectively. The polymer-bitumen blending conditions were optimized and the samples analyzed by different methodologies. Fluorescence microscopy, rotational viscosity and differential scanning calorimetry (DSC) were used to study the morphological changes of blends during their manufacturing and the rheological and thermal behavior, respectively. All modified bitumen (MB) exhibited higher viscosity than the based bitumen (BB) under studied conditions and this effect was more evident for the MB containing the higher molecular weight polymer. The addition of polymers to BB enhances the bitumen viscosity and thus increased the energy required for the flowing (activation energy calculated by Arrhenius equation). Thermal and morphological analysis showed that all MB exhibited good polymer- bitumen compatibility, which could be consider as a good starting point for a potential applications of this new material in road engineering. 相似文献
76.
Dayana Pereira de Andrade Cíntia Lacerda Ramos Diego Alvarenga Botrel Soraia Vilela Borges Rosane Freitas Schwan Disney Ribeiro Dias 《International Journal of Food Science & Technology》2019,54(7):2355-2362
The probiotic strains Lactobacillus brevis CCMA1284 and Lactobacillus plantarum CCMA0359 were microencapsulated by spray drying using different matrices – whey powder (W), whey powder with inulin (WI) and whey powder with maltodextrin (WM). Viability of the microencapsulated strains in acid and bile juices and during 90 days of storage (seven and 25 °C) was evaluated. The two strains exhibited high encapsulation efficiency (> 86%) by spray drying. The different matrices maintained L. plantarum viability above six log CFU g−1 at 7 °C for 90 days, whereas similar results for L. brevis were observed only for W. The use of inulin as matrix of encapsulation did not enhance bacterial viability in the evaluated conditions. In general, the use of W and WM as matrices was effective for L. plantarum viability. However, only W was effective for L. brevis in the evaluated conditions. The spray drying technique was successfully adopted for the encapsulation of L. plantarum CCMA0359 and L. brevis CCMA1284 strains. 相似文献
77.
The airflow behavior in a fluidization unit was integrally studied by means of experimental work and computational fluid dynamics simulation. The computational domain included the gas inlet pipe, plenum, perforated plate, fluidization chamber, and air outlet pipe. Different scenarios were simulated to allow distinguishing the best way to represent perforated‐plate distributors and elucidate the impact of the grid design on the fluidization performance. The simulated pressure drop across the distributor and the plenum flow pattern were in concordance with the experimental data. It was found that the distance between the peripheral holes and walls has a great impact on the airflow downstream the distributor. 相似文献
78.
Diego Fernández-Francos David Martínez-Rego Oscar Fontenla-Romero Amparo Alonso-Betanzos 《Computers & Industrial Engineering》2013,64(1):357-365
Rolling-element bearings are among the most used elements in industrial machinery, thus an early detection of a defect in these components is necessary to avoid major machine failures. Vibration analysis is a widely used condition monitoring technique for high-speed rotating machinery. Using the information contained in the vibration signals, an automatic method for bearing fault detection and diagnosis is presented in this work. Initially, a one-class ν-SVM is used to discriminate between normal and faulty conditions. In order to build a model of normal operation regime, only data extracted under normal conditions is used. Band-pass filters and Hilbert Transform are then used sequentially to obtain the envelope spectrum of the original raw signal that will finally be used to identify the location of the problem. In order to check the performance of the method, two different data sets are used: (a) real data from a laboratory test-to-failure experiment and (b) data obtained from a fault-seeded bearing test. The results showed that the method was able not only to detect the failure in an incipient stage but also to identify the location of the defect and qualitatively assess its evolution over time. 相似文献
79.
In this paper we present the use of static temperature measurements as process variation observable. Contrary to previously published thermal testing methods, the proposed methodology does not need an excitation signal, thus reducing test cost and improving built-in capabilities of thermal monitoring. The feasibility of the technique and a complete test methodology is presented using a narrowband LNA as example. Finally, a complete electro-thermal co-simulation test bench between the LNA and a differential temperature sensor embedded in the same silicon die is presented in order to validate the results. Results prove that RF figures of merit can be extracted from DC temperature measurements done without loading or exciting the RF circuit under test. 相似文献
80.
Insight into the gas‐phase glycerol dehydration on transition metal modified aluminium phosphates and zeolites 下载免费PDF全文