全文获取类型
收费全文 | 355篇 |
免费 | 11篇 |
专业分类
电工技术 | 4篇 |
综合类 | 2篇 |
化学工业 | 83篇 |
金属工艺 | 4篇 |
机械仪表 | 7篇 |
建筑科学 | 14篇 |
矿业工程 | 2篇 |
能源动力 | 11篇 |
轻工业 | 36篇 |
水利工程 | 2篇 |
无线电 | 19篇 |
一般工业技术 | 52篇 |
冶金工业 | 39篇 |
自动化技术 | 91篇 |
出版年
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 12篇 |
2019年 | 10篇 |
2018年 | 13篇 |
2017年 | 13篇 |
2016年 | 17篇 |
2015年 | 13篇 |
2014年 | 12篇 |
2013年 | 16篇 |
2012年 | 18篇 |
2011年 | 16篇 |
2010年 | 11篇 |
2009年 | 15篇 |
2008年 | 14篇 |
2007年 | 13篇 |
2006年 | 11篇 |
2005年 | 14篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 14篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1979年 | 5篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 3篇 |
1967年 | 1篇 |
排序方式: 共有366条查询结果,搜索用时 0 毫秒
41.
42.
43.
44.
45.
A C0 finite element method in which rotations and displacements are coupled by a penalty function formulation is developed for pipe line analysis. Inextensibility is also handled by a penalty method. Simplicity and effectiveness of this approach is illustrated by three dimensional computations including contact problems and an appendix giving all necessary stiffness matrices. 相似文献
46.
M. Şölener E. Uğuzdoğan M. Nurbaş T. Çamlı O.S. Kabasakal S. Patır A. Tuncel 《Polymer Bulletin》2006,57(3):341-349
Summary A new temperature sensitive hydrogel matrix, poly(N-ethoxypropylacrylamide), PNEPAM, was obtained by the bulk polymerization
of N-ethoxypropylacrylamide (NEPAM). The monomer, NEPAM was synthesized by the nucleophilic substitution reaction of 3-ethoxypropylamine
and acryloyl chloride. The polymerization was performed at +4 °C, by using N,N-methylenebisacrylamide (MBAM) as crosslinker,
polyethyleneglycol (PEG) 4000 as diluent, and potassium persulfate (KPS) and tetramethylethylenediamine (TEMED) as the initiator
and accelerator, respectively. PNEPAM gel matrices exhibited a thermosensitive bahaviour reasonably similar to poly(N-isopropylacrylamide),
PNIPAM gels. The equilibrium swelling ratio at constant temperature increased with increasing initiator concentration and
decreasing monomer concentration. The use of PEG 4000 as a diluent in the gel synthesis resulted in a significant enhacement
in the thermosensitivity of gel matrix. The equilibrium swelling ratios up to 60 g water/g dry gel were observed in the low-temperature
region. The results indicated that PNEPAM gel is a new alternative thermosensitive material to the NIPAM based gels. 相似文献
47.
Shepard Winifred O.; Cohen Debra; Gold Lee; Orbino Pat 《Canadian Metallurgical Quarterly》1976,12(5):477
Attempted to show that false recognition errors would be more frequently elicited by children's personal associates to a set of target words than by associates based on peer norms; Ss were 80 White middle-class 2nd and 5th graders (mean ages, 7.6 and 10.6 yrs, respectively). In Session 1 Ss gave oral associations to 34 words. In the 1st phase of Session 2, target words were each read aloud once and Ss were required to memorize them; in the 2nd phase Ss worked for 5 min on a maze task to prevent rehearsal; and in the final phase, a 40-item recognition list was read. Ss determined whether a word was one they had been asked to remember. As predicted, responses occurred with decreasing frequency to target, personal, peer, and control words. Consistent with the expectation that personal associates would more frequently elicit false recognition errors than would peer associates, the difference between personal and control responses was larger than the difference between peer and control. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
48.
Mechanical and thermal-mechanical treatments of 304 stainless steel enables yield strengths of over 200,000 psi to be obtained
with elongations better than 10 pct. Electron microscopy, X-ray, and magnetic techniques show that during deformation, strain
induced γ → ∈ → α transformation occurs with further thermal nucleation of α achieved by aging up to 400°C. The yield strength
is linearly proportional to the amount of ° irrespective of the treatment used to form α. The yield strength is given by αy = 225f + 48.65 ksi, where ƒ is the volume fraction of martensite. Softening occurs by aging at 500°C and above due to a decrease
in percent α which may occur by renucleation of γ. The system is an unusual form of composite strengthening; hard martensite
particles are formed within the austenite, and the percent α (and thereby the mechanical properties), can be controlled by
the mechanical/thermal-mechanical processing.
Formerly with the Department of Materials Science and Engineering, University of California, Berkeley, Calif. 相似文献
49.
Kong H. Lee Pat M. Lee Yew S. Siaw Kazuyuki Morihara 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1993,56(4):375-381
Elastase isolated from Pseudomonas aeruginosa IFO 3455 was found to be an efficient protease to catalyse the synthesis of N-benzyloxycarbonyl-aspartyl-phenylalanine methyl ester, the precursor of the dipeptide sweetener, aspartame. The influence of methanol as a cosolvent in this synthetic reaction was investigated. It was found that the synthesis of the dipeptide precursor was most efficient in 25% (v/v) methanol, pH 7·0 at about 25°C for a reaction time of about 3 h. However, the activity of the enzyme was greatly reduced in 90% methanol. The values of K and k2 for N-benzyloxycarbonyl-aspartic acid were 0·17 mol dm?3 and 11·9 mol dm?3 s?1 respectively. 相似文献
50.
Tom F. OCallaghan David T. Mannion Deirdre Hennessy Stephen McAuliffe Maurice G. OSullivan Natasha Leeuwendaal Tom P. Beresford Pat Dillon Kieran N. Kilcawley Jeremiah J. Sheehan R. Paul Ross Catherine Stanton 《Journal of dairy science》2017,100(8):6053-6073
The purpose of this study was to investigate the effects of pasture-based versus indoor total mixed ration (TMR) feeding systems on the chemical composition, quality characteristics, and sensory properties of full-fat Cheddar cheeses. Fifty-four multiparous and primiparous Friesian cows were divided into 3 groups (n = 18) for an entire lactation. Group 1 was housed indoors and fed a TMR diet of grass silage, maize silage, and concentrates; group 2 was maintained outdoors on perennial ryegrass only pasture (GRS); and group 3 was maintained outdoors on perennial ryegrass/white clover pasture (CLV). Full-fat Cheddar cheeses were manufactured in triplicate at pilot scale from each feeding system in September 2015 and were examined over a 270-d ripening period at 8°C. Pasture-derived feeding systems were shown to produce Cheddar cheeses yellower in color than that of TMR, which was positively correlated with increased cheese β-carotene content. Feeding system had a significant effect on the fatty acid composition of the cheeses. The nutritional composition of Cheddar cheese was improved through pasture-based feeding systems, with significantly lower thrombogenicity index scores and a greater than 2-fold increase in the concentration of vaccenic acid and the bioactive conjugated linoleic acid C18:2 cis-9,trans-11, whereas TMR-derived cheeses had significantly higher palmitic acid content. Fatty acid profiling of cheeses coupled with multivariate analysis showed clear separation of Cheddar cheeses derived from pasture-based diets (GRS or CLV) from that of a TMR system. Such alterations in the fatty acid profile resulted in pasture-derived cheeses having reduced hardness scores at room temperature. Feeding system and ripening time had a significant effect on the volatile profile of the Cheddar cheeses. Pasture-derived Cheddar cheeses had significantly higher concentrations of the hydrocarbon toluene, whereas TMR-derived cheese had significantly higher concentration of 2,3-butanediol. Ripening period resulted in significant alterations to cheese volatile profiles, with increases in acid-, alcohol-, aldehyde-, ester-, and terpene-based volatile compounds. This study has demonstrated the benefits of pasture-derived feeding systems for production of Cheddar cheeses with enhanced nutritional and rheological quality compared with a TMR feeding system. 相似文献