全文获取类型
收费全文 | 260篇 |
免费 | 7篇 |
专业分类
电工技术 | 2篇 |
综合类 | 1篇 |
化学工业 | 86篇 |
金属工艺 | 3篇 |
机械仪表 | 3篇 |
建筑科学 | 4篇 |
能源动力 | 2篇 |
轻工业 | 21篇 |
水利工程 | 2篇 |
石油天然气 | 2篇 |
无线电 | 20篇 |
一般工业技术 | 53篇 |
冶金工业 | 47篇 |
自动化技术 | 21篇 |
出版年
2023年 | 4篇 |
2022年 | 23篇 |
2021年 | 22篇 |
2020年 | 6篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 9篇 |
2015年 | 12篇 |
2014年 | 10篇 |
2013年 | 16篇 |
2012年 | 16篇 |
2011年 | 19篇 |
2010年 | 5篇 |
2009年 | 7篇 |
2008年 | 12篇 |
2007年 | 5篇 |
2006年 | 4篇 |
2005年 | 11篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 8篇 |
1997年 | 9篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1934年 | 1篇 |
排序方式: 共有267条查询结果,搜索用时 15 毫秒
31.
The kink effect in InAlAs/InGaAs/InP composite channel heterojunction field effect transistors (HFETs) was investigated as a function of temperature and optical excitation. Drain source and gate current measurements show that above 325 K the kink effect disappears while the impact ionization process is still present. The kink at low temperatures is suppressed by illumination with photons of energy above 1 eV. These results prove that this parasitic effect is mainly related to the presence of traps in the top layers 相似文献
32.
Son Hing Leanne S.; Bobocel D. Ramona; Zanna Mark P.; McBride Maxine V. 《Canadian Metallurgical Quarterly》2007,92(1):67
When dilemmas require trade-offs between profits and ethics, do leaders high in social dominance orientation (SDO) and followers high in right-wing authoritarianism (RWA) make decisions that are more unethical than those made by others? This issue was explored in 4 studies with female participants performing managerial role-playing tasks. First, dyads comprising a person who was either low or high in SDO and a person who was either low or high in RWA negotiated for a leadership position. People high in SDO were more likely to obtain leader positions than to obtain follower positions. No other effects were significant. Second, leaders high in SDO partnered with an agreeable (confederate) follower made decisions that were more unethical than those of leaders low in SDO. Third, followers high in RWA were more acquiescent to and supportive of an unethical (confederate) leader than were followers low in RWA. Fourth, high SDO leader-high RWA follower dyads made decisions that were more unethical than those made in role-reversed dyads because leaders had more influence. Implications of these results for conceptualizing SDO, RWA, and authoritarian dynamics are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
33.
Supported mixture metal oxide systems, Cu---Cr and Co---Cr on γ-A12O3 and γ-A12O3+ SiO2 were prepared and studied. They exhibited catalytic activity in the complete oxidation of benzene. 相似文献
34.
Medium chain 2-hydroxy fatty acids and 3-hydroxy fatty acids (2-OH-FAs and 3-OH-FAs with 8–20 carbons) are widespread in nature but little was known about the quantities of these minor fatty acids in food. For this reason, the concentrations and composition of 2- and 3-OH-FAs in several foodstuffs (milk and dairy products, animal brains, suet, vegetable oils) and two non-food samples (wool wax and vernix caseosa) were determined by gas chromatography with electron-capture negative ion mass spectrometry in the selected ion monitoring mode. Lipids were isolated from samples by accelerated solvent extraction. After transesterification the obtained fatty acid methyl esters (FAMEs) were separated into OH-FAMEs and non-OH-FAMEs. The OH-FAMEs were converted into pentafluorobenzoyl (PFBO) derivatives (PFBO-O-FAMEs). 2- and 3-OH-FAs were detected in all samples analysed. Chain-length ranged from 8–20 carbons. In general, 3-OH-FAs dominated in milk and dairy products (maximum concentration 17.7 mg/100 g l.w. in goat milk) whereas 2-OH-FAs were more abundant in animal brains and suet. The lowest concentrations were determined in vegetable oils (0.21–2.42 mg/100 g l.w.) whereas the highest concentrations of 2-OH-FAs were determined in wool wax (1180 mg/100 g l.w.) and vernix caseosa (34.5 mg/100 g l.w.). 相似文献
35.
The present paper continues to compare and analyse the most recent design codes formulae for interactive buckling of thin-walled members. A first analysis was performed using a statistical comparison between theoretical and experimental results and was presented at the SSRC Annual Technical Session, held in Pittsburgh. An analytic comparison between ECCS 1987, EUROCODE 3, AISI and the author's formula is performed. A proposal for a cross-sections classification from the point of view of an ‘erosion factor’ is also presented. 相似文献
36.
Ramona María Díaz Ana María Fernndez Jorge Xiberta 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1986,36(6):273-280
The distribution equilibrium data at 25°C for the extraction of copper from aqueous solutions, containing sodium nitrate or sodium sulphate, by carboxylic acids using toluene, benzene and carbon tetrachloride as diluents have been measured. The carboxylic acids used are n-myristic, n-lauric and n-capric. The results obtained led to the conclusion that the composition of the extracted species corresponds to (CuR2.HR)2, being irrespective of both the nature of organic phase and the aqueous phase. The addition of sodium sulphate, instead of sodium nitrate, decreases the extraction efficiency due to the formation a CuSO4 ion-pair into the aqueous phase. The diluent effect has been related to the activity of the dimerised carboxylic acid in the diluent. 相似文献
37.
V Mogo? E Zbranca V Strat MR Diaconescu M Chifan N Florea G Cost?chescu MR G?le?anu V Rusu G Georgescu 《Canadian Metallurgical Quarterly》1995,99(1-2):72-81
We have analysed factors that influenced on the patient survival in 195 cases of thyroid cancer. The survival is essentially influenced by the histology, the papillary forms (survival after 15 years: 83.1-93%) and follicular cancers (survival after 15 years: 84-94%) having an excellent evolution. The non-differentiated and mixed cancers have a very severe prognosis that is independent of the complex therapy that have been used (survival after 5 years: 17.1% in non-differentiated forms and 32.5% in mixed ones). The prognosis is better in subjects under the age of 45 and in female subjects. The cancers in the 1-st and 2-nd stage of tumor extension have a better evolution that those in the 3-rd stage. In differentiated cancers, the total or subtotal thyroidectomy followed by radioiodine administration determine the best survival. 相似文献
38.
39.
Anti-listerial activity of a polymeric film coated with hybrid coatings doped with Enterocin 416K1 for use as bioactive food packaging 总被引:1,自引:0,他引:1
Iseppi R Pilati F Marini M Toselli M de Niederhäusern S Guerrieri E Messi P Sabia C Manicardi G Anacarso I Bondi M 《International journal of food microbiology》2008,123(3):281-287
In this study, Enterocin 416K1, a bacteriocin produced by Enterococcus casseliflavus IM 416K1, was entrapped in an organic-inorganic hybrid coating applied to a LDPE (low-density polyethylene) film for its potential use in the active food packaging field. The antibacterial activity of the coated film was evaluated against Listeria monocytogenes NCTC 10888 by qualitative modified agar diffusion assay, quantitative determination in listeria saline solution suspension and direct contact with artificially contaminated food samples (frankfurters and fresh cheeses) stored at room and refrigeration temperatures. All investigations demonstrated that enterocin-activated coatings have a good anti-listeria activity. Qualitative tests showed a clear zone of inhibition in the indicator lawn in contact with and around the coated film. During the quantitative antibacterial evaluation the L. monocytogenes viable counts decreased to 1.5 log units compared to the control. The inhibitory capability was confirmed also in food-contact assays. In all food samples packed with coated films we observed a significant decrease in L. monocytogenes viable counts in the first 24 h compared to the control. This difference was generally maintained up to the seventh day and then decreased, with the exception of the cheese samples stored at refrigeration temperature. 相似文献
40.
Wireless Networks - As mobile devices have become more affordable, easy to use and powerful, the number of mobile users and their bandwidth demands have experienced a significant growth.... 相似文献