全文获取类型
收费全文 | 1194篇 |
免费 | 97篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 411篇 |
金属工艺 | 14篇 |
机械仪表 | 29篇 |
建筑科学 | 57篇 |
矿业工程 | 1篇 |
能源动力 | 33篇 |
轻工业 | 291篇 |
水利工程 | 7篇 |
石油天然气 | 6篇 |
无线电 | 73篇 |
一般工业技术 | 132篇 |
冶金工业 | 83篇 |
原子能技术 | 2篇 |
自动化技术 | 150篇 |
出版年
2024年 | 2篇 |
2023年 | 9篇 |
2022年 | 17篇 |
2021年 | 94篇 |
2020年 | 39篇 |
2019年 | 46篇 |
2018年 | 43篇 |
2017年 | 40篇 |
2016年 | 52篇 |
2015年 | 48篇 |
2014年 | 52篇 |
2013年 | 85篇 |
2012年 | 86篇 |
2011年 | 80篇 |
2010年 | 73篇 |
2009年 | 71篇 |
2008年 | 81篇 |
2007年 | 61篇 |
2006年 | 47篇 |
2005年 | 40篇 |
2004年 | 35篇 |
2003年 | 24篇 |
2002年 | 23篇 |
2001年 | 27篇 |
2000年 | 13篇 |
1999年 | 12篇 |
1998年 | 9篇 |
1997年 | 10篇 |
1996年 | 11篇 |
1995年 | 12篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 2篇 |
排序方式: 共有1291条查询结果,搜索用时 15 毫秒
101.
Carla Da Porto Deborha Decorti Franco Tubaro 《International Journal of Food Science & Technology》2011,46(5):988-993
Some Dominican ‘heavy’ rums, of a single brand, available commercially and labelled as 8, 15, 18, 21 and 25 year‐old have been evaluated and compared. Headspace solid‐phase microextraction (HS‐SPME) coupled to gas chromatography–mass spectrometry (GC–MS) was used to analyse volatile compounds and crocin kinetic competition test to evaluate their antioxidant capacity. The alcohols and esters profiles of rums labelled as 21‐ and 25 year‐old were similar. The alcohols and fatty acids profiles of rums labelled as 15 and 18 year‐old were similar. The esters profile of rums labelled as 8 and 15 year‐old was similar. Significant differences were found for aldehydes and volatile phenols between all the rum samples. The antioxidant capacity resulted significantly higher in the older rums (21 and 25 year‐old) than in the younger ones (8, 15 and 18 year‐old). 相似文献
102.
John W. Finley Carla Sandlin Darryl L. Holliday Michael J. Keenan Witoon Prinyawiwatkul Jolene Zheng 《Journal of Functional Foods》2013,5(3):1487-1493
Wild type Caenorhabditis elegans (C. elegans) were fed with powdered legumes (1%, w/v): light red kidney, black, navy, white kidney, cranberry, great northern, lentil, lima, or dark red kidney (20%, 33% and 50% of a 1% suspension). Lipophilic fluorescent Nile red dye-stained intestinal fat deposition (IFD) indicated an IFD reduction by legumes in a descending order: light red kidney, black, navy, white kidney, cranberry, great northern, lentil, lima, or dark red kidney. Increased pharyngeal pumping rate (PPR), a surrogate marker of aging, was observed in all legumes at 50% dosage. Both inverse and direct relationships between IFD and PPR were detected in the wild type C. elegans in this study. These results suggested that whole legumes may promote health through regulation of lipid metabolism and lifespan in the model system C. elegans, which enhances our understanding of the effect of legumes and suggests further legumes study in human health. 相似文献
103.
Priscila M.A. Alves Rosemary A. CarvalhoIzabel C.F. Moraes Carla G. LucianoAna Mônica Q.B. Bittante Paulo J.A. Sobral 《Food Hydrocolloids》2011
Both gelatin and poly(vinyl alcohol) (PVA) can be cross linked with glutaraldehyde (GLU). In the case of gelatin, the GLU reacts with each ε-NH2 functional group of adjacent lysine residues, while for PVA, the GLU reacts with two adjacent hydroxyl groups, forming acetal bridges. Thus it can be considered possible to cross link adjacent macromolecules of gelatin and PVA using GLU. In this context, the aims of this work were the development of biodegradable films based on blends of gelatin and poly(vinyl alcohol) cross linked with GLU, and the characterization of some of their main physical and functional properties. All the films were produced from film-forming solutions (FFS) containing 2 g macromolecules (PVA + gelatin)/100 g FFS, 25 g glycerol/100 g macromolecules, and 4 g GLU (25% solution)/100 g FFS. The FFS were prepared with two concentrations of PVA (20 or 50 g PVA/100 g macromolecules) and two reaction temperatures: 90 or 55 °C, applied for 30 min. The films were obtained after drying (30 °C/24 h) and conditioning at 25 °C and 58% of relative humidity for 7 days, and were then characterized. The results for the color parameters, mechanical properties, phase transitions and infrared spectra showed that some chemical modifications occurred, principally for the gelatin. However, in general, all the characteristics of the films were either typical of films based on blends of these macromolecules without cross linking, or slightly higher. A greater improvement in the properties of this material was probably not observed due to the crystallinity of the PVA, which has a melting point above 90 °C. The presence of microcrystals in the polymer chain probably reduced macromolecular mobility, hindering the reaction. Thus more research is necessary to produce biodegradable films with improved properties. 相似文献
104.
The study investigated the effect of wearing chipper knives on machine productivity, fuel consumption and particles size distribution. The test included two different tree species (poplar and pine), two tree parts (branches and logs) and two screen types (large and medium). Chip quality was defined by CEN international technical standards. Knife wear causes a significant reduction of chipping productivity and a remarkable increase of fuel consumption. The replacement of the standard wide mesh screen with a narrower screen has a similar effect, further decreasing productivity and increasing fuel consumption. For the same screen type and knife wear level, productivity and fuel consumption are the same for poplar and pine. Knife, tree species and tree part also have a significant impact on chip size distribution. Chips produced from logs always contain a smaller proportion of oversize particles and a higher proportion of accepts. For the same large mesh screen, poplar chips tend to be larger than pine chips and to contain a higher proportion of oversize particles. On the contrary, pine chips tend to be smaller and to contain a higher proportion of fines. The use of a narrower mesh screen on pine material does not seem to offer any significant reduction of oversize particles, whose presence is already very limited. Therefore, a standard large mesh screen should be used when chipping pine material. 相似文献
105.
Carla Da Porto Deborha Decorti Andrea Natolino 《International Journal of Food Science & Technology》2013,48(10):2127-2132
Conventional solvent extraction (CE) and ultrasound‐assisted extraction (UAE) in hexane for oil from untreated and enzyme‐treated grape seeds were investigated and compared. Among the output power tested (50, 100 and 150 W) in UAE on untreated seeds, UAE at 150 W for 30 min with liquid‐to‐solid ratio 8:1 (v/w) gave oil extraction yield comparable to CE (ca. 14% w/w) for 6 h with liquid‐to‐solid ratio 12:1 (v/w). CE and UAE at 150 W did not influence the fatty acid profiles of oil. CE oil was found to be the most oxidised. The enzymatic treatments (2, 4 and 6 g per 100 g seeds of Rapidase® Expression) prior to CE enhanced by 2.5% of the oil yield. Enzymatic treatments higher than 2 g per 100 g seeds increased relative value of some fatty acids both in CE and UAE. Enzymatic pretreatment from 2 to 4 g per 100 g seeds significantly improved some physicochemical parameters of oil quality when extracted by CE, but not by UAE. 相似文献
106.
Suyeon Kim Carla Silva Andrea Zille Carmen Lopez Dmitry V Evtuguin Artur Cavaco‐Paulo 《Polymer International》2009,58(8):863-868
BACKGROUND: The ‘double function’ of laccase, from the ascomycete Myceliophthora, to depolymerise/polymerise lignin was studied in this work. A lignosulfonate (LS) compound was oxidised by enzymatic action and several techniques were applied to measure the polymeric changes obtained. This study was focused on the attachment level of the oxidised LS at the flax surface. RESULTS: Modified solutions were studied in terms of surface charge. Zeta potential values obtained showed an increase of polymerisation after several days of incubation. The change in molecular weight after LS polymerisation was detected using gel permeation chromatography. An increase of 1700 Da was achieved. Fourier transform infrared and UV‐visible spectroscopy techniques were applied and the results showed an increase of the degree of polymerisation. The colour strength of flax fabrics incubated with oxidised LS solutions was also measured and an increase of K/S (K, absorption coefficient; S, scattering coefficient) after enzymatic oxidation was observed. CONCLUSION: The oxidised lignin products obtained show good potential for use in natural surface modification of textile materials containing flavonoids. These findings have important practical implications for lignocellulosic fibre coloration, where new polymers can replace harsh chemicals in the textile industry. Copyright © 2009 Society of Chemical Industry 相似文献
107.
F. Frezza A. Galli G. Gerosa P. Lampariello 《Journal of Infrared, Millimeter and Terahertz Waves》1995,16(3):675-688
In this paper the fundamental effects of losses on resonant parameters (frequencies and quality factors) are analyzed for circular-cylindrical dielectric resonators inserted between metal plates, in the configuration also called NRD (Non-Radiative Dielectric). Power dissipations are considered both in the dielectric and in the conductors. Complex resonant frequencies and closed-form expressions for the relevant quality factors are derived rigorously for arbitrary resonant modes, even without circular symmetry. Numerical results are presented and discussed, making also use of experimental data obtained by means of a suitable NRD set-up. The present analysis accurately provides the basic information for a more realistic design of up-to-date millimeter-wave frequency-selective devices in NRD circuitry. 相似文献
108.
T. Canli et al., 2004 (see record 2004-19432-002) use functional MRI to explore the neural interface between personality, mood, and emotional responses. Their finding of a double dissociation in brain response to emotional stimuli based on personality and mood state has significant implications for our understanding of the effects of personality traits and mood states on the neural bases of emotion and cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
109.
Boone Kyle Brauer; Lesser Ira M.; Miller Bruce L.; Wohl Marcy; Berman Nancy; Lee Alison; Palmer Barton; Back Carla 《Canadian Metallurgical Quarterly》1995,9(3):390
Neuropsychological evaluation of 73 older healthy, unmedicated outpatients with major depression and 110 controls suggested that relatively distinct cognitive profiles may correspond to the presence vs. severity of depression. Specifically, the presence of depression was associated with subtle weaknesses in visual memory and nonverbal intelligence, with sparing of verbal skills (verbal intelligence, language, and verbal memory), constructional ability, attention, information processing speed, and executive functions. In contrast, increasing severity of depression was associated with mild weaknesses, primarily in information-processing speed and executive skills, but was essentially unrelated to memory (verbal or visual), intelligence, language skills, constructional ability, or basic attention. Findings are discussed in terms of a possible state vs. trait model of depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
110.
We characterize finite dimensional realizability of discrete time nonlinear systems which have a Volterra series development with separable structure of the Volterra kernels. 相似文献