全文获取类型
收费全文 | 1452篇 |
免费 | 92篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 17篇 |
综合类 | 4篇 |
化学工业 | 446篇 |
金属工艺 | 26篇 |
机械仪表 | 42篇 |
建筑科学 | 45篇 |
矿业工程 | 9篇 |
能源动力 | 39篇 |
轻工业 | 219篇 |
水利工程 | 15篇 |
石油天然气 | 8篇 |
无线电 | 69篇 |
一般工业技术 | 233篇 |
冶金工业 | 112篇 |
原子能技术 | 3篇 |
自动化技术 | 258篇 |
出版年
2024年 | 6篇 |
2023年 | 11篇 |
2022年 | 60篇 |
2021年 | 85篇 |
2020年 | 57篇 |
2019年 | 54篇 |
2018年 | 71篇 |
2017年 | 72篇 |
2016年 | 69篇 |
2015年 | 55篇 |
2014年 | 59篇 |
2013年 | 114篇 |
2012年 | 103篇 |
2011年 | 109篇 |
2010年 | 91篇 |
2009年 | 109篇 |
2008年 | 65篇 |
2007年 | 60篇 |
2006年 | 55篇 |
2005年 | 29篇 |
2004年 | 19篇 |
2003年 | 31篇 |
2002年 | 24篇 |
2001年 | 12篇 |
2000年 | 6篇 |
1999年 | 12篇 |
1998年 | 27篇 |
1997年 | 24篇 |
1996年 | 11篇 |
1995年 | 9篇 |
1994年 | 11篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1977年 | 1篇 |
1973年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有1545条查询结果,搜索用时 15 毫秒
91.
Thales Leandro Coutinho de Oliveira Rodrigo de Araújo Soares Roberta Hilsdorf Piccoli 《Meat science》2013
The antimicrobial effect of oregano (Origanum vulgare L.) and lemongrass (Cymbopogon citratus (DC.) Stapf.) essential oils (EOs) against Salmonella enterica serotype Enteritidis in in vitro experiments, and inoculated in ground bovine meat during refrigerated storage (4 ± 2 °C) for 6 days was evaluated. The Weibull model was tested to fit survival/inactivation bacterial curves (estimating of p and δ parameters). The minimum inhibitory concentration (MIC) value for both EOs on S. Enteritidis was 3.90 μl/ml. The EO concentrations applied in the ground beef were 3.90, 7.80 and 15.60 μl/g, based on MIC levels and possible activity reduction by food constituents. Both evaluated EOs in all tested levels, showed antimicrobial effects, with microbial populations reducing (p ≤ 0.05) along time storage. Evaluating fit-quality parameters (RSS and RSE) Weibull models are able to describe the inactivation curves of EOs against S. Enteritidis. The application of EOs in processed meats can be used to control pathogens during refrigerated shelf-life. 相似文献
92.
93.
This work is focussed on the application of an electrochemical technology to regenerate the bonding agent of a polymer-supported ultrafiltration process, technique commonly used to remove metal ions from wastewaters. To do this, a batch rotating-electrode electrochemical cell has been set up to recover the copper bind to partially ethoxylated polyethyleneimine by electrodeposition. The influence of the main parameters (current efficiency, stirring rate, pH, electrode material and nature of the counterion) on the performance of the process has been studied. Current efficiency is clearly enhanced with the stirring rate, reaching values as high as 0.93 for the optimum working conditions. Regarding pH, this variable has been observed to play an important role in process efficiency. Thus, it has been found that the reactor can operate at pH 4 without affecting process performance. This is a clear advantage with respect to other regeneration techniques and also to previous works of electrochemical regeneration. The electrode material seems to have a clear influence on process behaviour and especially on the appearance of a first transitory stage with lower current efficiency. Finally, the electrolyte salt also influences significantly on the results and the presence of sulphate as counterion leads to the best system performance. 相似文献
94.
95.
Concentration of Gamma‐Linolenic and Stearidonic Acids as Free Fatty Acids and Ethyl Esters from Viper's Bugloss Seed Oil by Urea Complexation 下载免费PDF全文
96.
97.
We give a new, and hopefully more easily understandable, structural proof of the decomposition of a k-valued transducer into k unambiguous functional ones, a result established by A. Weber in 1996. Our construction is based on a lexicographic ordering
of computations of automata and on two coverings that can be build by means of this ordering. The complexity of the construction,
measured as the number of states of the transducers involved in the decomposition, improves the original one by one exponential. 相似文献
98.
Fundamental Parameters for the Stiffness and Strength Control of Artificially Cemented Sand 总被引:1,自引:0,他引:1
Nilo Cesar Consoli António Viana da Fonseca Rodrigo Caberlon Cruz Karla Salvagni Heineck 《Canadian Metallurgical Quarterly》2009,135(9):1347-1353
The treatment of soils with cement is an attractive technique when the project requires improvement of the local soil for the construction of subgrades for rail tracks, as a support layer for shallow foundations and to prevent sand liquefaction. As reported by Consoli et al. in 2007, a unique dosage methodology has been established based on rational criteria where the voids/cement ratio plays a fundamental role in the assessment of the target unconfined compressive strength. The present study broadened the research carried out by Consoli et al. in 2007 through quantifying quantifies the influence of voids/cement ratio on the initial shear modulus (G0) and Mohr-Coulomb effective strength parameters (c′,?′) of an artificially cemented sand. A number of unconfined compression and triaxial compression tests with bender elements measurements were carried out. It was shown that the void/cement ratio defined as the ratio between the volume of voids of the compacted mixture and the volume of cement is an appropriate parameter to assess both initial stiffness and effective strength of the sand-cement mixture studied. 相似文献
99.
100.
Rodrigo Verschae Mario Koeppen Kaori Yoshida 《Simulation Modelling Practice and Theory》2011,19(1):47-55
The incorporation of user-supplied information has become mandatory for the improvement of QoS in network systems. There is the question about accommodation of new users of a service, given that information about former users of a service is available. In the present work, we followed two approaches to derive information about new users in the network design and control processes, where both are based on prototype generation for the answers of former users to a QoS related questionnaire. In the first approach, attempts were made to map user attributes to prototypes. The second approach used a mapping from partial answers to a prototype. As a result, the first approach appeared to be infeasible, while the second showed good results. In the resulting trade-off between number of prototypes and classification accuracy, it is possible, for example, with 8 prototypes for around 1000 users to predict the answers of new users by using only 30% of the answers of former users, while reducing accuracy by only 13% at the same time. 相似文献