全文获取类型
收费全文 | 752篇 |
免费 | 51篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 228篇 |
金属工艺 | 6篇 |
机械仪表 | 12篇 |
建筑科学 | 22篇 |
矿业工程 | 1篇 |
能源动力 | 23篇 |
轻工业 | 203篇 |
水利工程 | 8篇 |
石油天然气 | 7篇 |
无线电 | 29篇 |
一般工业技术 | 87篇 |
冶金工业 | 77篇 |
原子能技术 | 6篇 |
自动化技术 | 93篇 |
出版年
2024年 | 3篇 |
2023年 | 6篇 |
2022年 | 35篇 |
2021年 | 41篇 |
2020年 | 14篇 |
2019年 | 29篇 |
2018年 | 30篇 |
2017年 | 24篇 |
2016年 | 29篇 |
2015年 | 34篇 |
2014年 | 35篇 |
2013年 | 34篇 |
2012年 | 53篇 |
2011年 | 57篇 |
2010年 | 43篇 |
2009年 | 46篇 |
2008年 | 38篇 |
2007年 | 40篇 |
2006年 | 32篇 |
2005年 | 32篇 |
2004年 | 18篇 |
2003年 | 16篇 |
2002年 | 14篇 |
2001年 | 5篇 |
2000年 | 8篇 |
1999年 | 7篇 |
1998年 | 13篇 |
1997年 | 9篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
排序方式: 共有804条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
P Cairns TJ Polascik Y Eby K Tokino J Califano A Merlo L Mao J Herath R Jenkins W Westra 《Canadian Metallurgical Quarterly》1995,11(2):210-212
BACKGROUND: Carcinoma of the breast is characterized by a variable course with prognosis dependent on disease stage at presentation. Paradoxically, some patients with early malignancy demonstrate disease progression within a short time. The role of tumor markers in the management of carcinoma of the breast is controversial. While CA15-3 is the most widely used tumor marker in carcinoma of the breast, its role in the management of patients with early disease is controversial. STUDY DESIGN: Since 1986, all patients presenting to our unit with carcinoma of the breast have had serial CA15-3 levels measured. This study evaluates the role of serial CA15-3 levels in the management of a consecutive series of 168 patients with Stage I disease at presentation. RESULTS: The mean preoperative CA15-3 levels at presentation were significantly elevated in patients with Stage I disease compared with patients with benign disease. Sixteen patients had either locoregional (five patients) or metastatic recurrence (11 patients). CA15-3 levels were not elevated in patients with locoregional disease and were significantly elevated in patients with bony metastases and gave a mean lead time of 6.3 months over bone scintigraphy. CONCLUSIONS: Serial CA15-3 measurements are an efficient and cost-effective method of monitoring disease progression and have advantages over conventional investigations in patients with early carcinoma of the breast. 相似文献
55.
María Fernndez Alicia de Coo Ins Quintela Eliane García Mrcio Diniz-Freitas Jacobo Limeres Pedro Diz Juan Blanco ngel Carracedo Raquel Cruz 《International journal of molecular sciences》2021,22(12)
Severe periodontitis is prevalent in Down syndrome (DS). This study aimed to identify genetic variations associated with periodontitis in individuals with DS. The study group was distributed into DS patients with periodontitis (n = 50) and DS patients with healthy periodontium (n = 36). All samples were genotyped with the “Axiom Spanish Biobank” array, which contains 757,836 markers. An association analysis at the individual marker level using logistic regression, as well as at the gene level applying the sequence kernel association test (SKAT) was performed. The most significant genes were included in a pathway analysis using the free DAVID software. C12orf74 (rs4315121, p = 9.85 × 10−5, OR = 8.84), LOC101930064 (rs4814890, p = 9.61 × 10−5, OR = 0.13), KBTBD12 (rs1549874, p = 8.27 × 10−5, OR = 0.08), PIWIL1 (rs11060842, p = 7.82 × 10−5, OR = 9.05) and C16orf82 (rs62030877, p = 8.92 × 10−5, OR = 0.14) showed a higher probability in the individual analysis. The analysis at the gene level highlighted PIWIL, MIR9-2, LHCGR, TPR and BCR. At the signaling pathway level, PI3K-Akt, long-term depression and FoxO achieved nominal significance (p = 1.3 × 10−2, p = 5.1 × 10−3, p = 1.2 × 10−2, respectively). In summary, various metabolic pathways are involved in the pathogenesis of periodontitis in DS, including PI3K-Akt, which regulates cell proliferation and inflammatory response. 相似文献
56.
Sabina Kokoszka Frederic Debeaufort Alicia Hambleton Andrzej Lenart Andree Voilley 《Innovative Food Science and Emerging Technologies》2010,11(3):503-510
This study was conducted to determine the effect of both soy protein and glycerol contents on physico-chemical properties of soy protein isolate-based edible (SPI) films. The aim of this study was to better understand the influence of SPI and GLY contents on the behavior of the physico-chemical properties of soy protein isolate-based films. Films were casted from heated (70 °C for 20 min) alkaline (pH 10) aqueous solutions of SPI at 6, 7, 8, and 9 (w/w %), glycerol (50%, w/w, of SPI) and SPI at 7 (w/w %), glycerol (40, 60, 70 %, w/w of SPI). Water vapor permeability (WVP), was measured at 25 °C and for four different relative humidities (30–100%, 30–84%, 30–75%, 30–53%). Surface properties and differential scanning calorimetry were also measured. Varying the proportion of SPI and GLY had an effect on water vapor permeability, wetting and thermal properties of SPI films. A synergistic effect of glycerol and protein was observed on the water vapor permeability. Glycerol and RH gradient strongly enhance the moisture absorption rates and permeability of SPI based films. SPI content weakly increases the WVP and does not modify the surface properties. The temperature of denaturation of soy protein decreases glycerol content except for the higher concentration whereas it increases with protein ratio.Industrial relevanceThis topic of research aims to control mass transfers within composite foods or betweenfoods and surrounding media (for instance the headspace in packagings). The targeted applications from this work deals with the food product coating or the coating of paper-based packaging for limiting both the loss of water and flavors by cheese based products. This will allow to maintain the weight of the cheese during “ripening” and commercialization, and also to prevent (off-) flavour dissemination from very odorant cheese as produced in France and Poland. 相似文献
57.
Anibal Mario Nervi Raul Omar Peluffo Rodolfo R. Brenner Alicia Isabel Leikin 《Lipids》1980,15(4):263-268
The effect of ethanol on the fatty acid desaturation by rat liver has been studied using liquid diets of different composition.
Acute ethanol administration increased triacylglycerols of total liver lipids, but did not modify significantly the lipidic
composition of microsomes. The Δ6 and Δ5 desaturases were inhibited by ethanol whereas the Δ9 desaturase and fatty acid synthetase
were apparently modified only by diet composition. NADH-cytochrome (cyt.) c reductase was partially inhibited, whereas NADH-cyt.
b5 reductase remained practically unaltered and NADPH-cyt. c reductase activity was enhanced. Decreased electrons supplied by
the microsomal cyt. b5 electron transport chain would not be the reason for the inhibition of Δ6 and Δ5 desaturases by ethanol. 相似文献
58.
Sonia Z. Viña Alicia Mugridge María A. García Ricardo M. Ferreyra Miriam N. Martino Alicia R. Chaves Noemí E. Zaritzky 《Food chemistry》2007,103(3):701-709
To extend shelf life, the effects of polyvinylchloride film (PVC) and edible coatings on quality aspects of refrigerated Brussels sprouts were studied. Starch-based coatings were formulated using glycerol (G), sorbitol (S) or glycerol plus sunflower oil (O). Sprouts so treated as well as uncoated ones were placed on expanded polystyrene trays. Combinations of PVC and coatings (treatments named G-PVC, S-PVC and O-PVC) were also tested. Uncovered trays were maintained as controls. All packages were stored at 0 °C for 42 days and samples were removed every 14 days to determine commercial acceptability, weight loss, surface colour (of sprouts’ heads and bases) and texture. Sprouts in all treatments maintained optimum quality conditions over the first 14 days. At the end of storage, browning of cut zones and losses in weight and firmness were minimised in PVC-packaged sprouts, particularly in G-PVC. Therefore, PVC and G-PVC treatments were selected to evaluate some nutritional quality components. Ascorbic acid and total flavonoid contents remained almost constant while radical scavenging activity increased after 42 days of storage. Thus, PVC and G-PVC treatments showed the best performance for long-term refrigerated storage of Brussels sprouts. 相似文献
59.
Alicia B. Brune Robert I. Mangham William T. Petuskey 《Journal of Materials Science》2008,43(2):621-634
Hydrogen-based niobates and niobate-titanates were derived from the pyrochlores Pb1.5Nb2O6.5 (PN) and Pb2Nb1.33Ti0.67O6.67 (PNT) by ion exchange in acid baths, affording sub-micron size white powders. The niobium sublattice was left intact, as
shown by X-ray diffraction. A combination of stripping and thermogravimetric analyses gave the effective formulas H2.66Pb0.17Nb2O6.5·0.5H2O (HPN) and H3.88Pb0.06Nb1.33Ti0.67O6.67·0.33H2O (HPNT). The corresponding structural refinements gave good fits to the XRD data. Densities measured by He pycnometry agreed
with densities calculated from XRD analyses and the effective formulas. Thermal stability was assessed by TGA, DSC, and XRD.
With increasing temperature, HPN and HPNT lost weight (H2O), becoming amorphous, and then transforming to crystalline phases, with greatly reduced particle size. HPN was more stable
than HPNT. The electrical conductivities of powder compacts in wet atmospheres were moderate and attributed mainly to proton
conduction; i.e., 10−6 to 10−5 S cm−1 for HPN and 10−7 to 10−6 S cm−1 for HPNT (from room temperature to 230 °C). Experimental results were interpreted in terms of Nb(V) being a stronger electron
acceptor than Ti(IV). 相似文献
60.
Fabiana D’Eramo María Alicia Zón Héctor Fernández Leonides Sereno Alejandro Heraldo Arévalo 《Electrochimica acta》2008,53(24):7182-7190
A novel conducting polymer of polynaphthidine, poly(NAP), was synthesized electrochemically by direct anodic oxidation of naphthidine in aqueous media. The yield of the electropolymerization reaction depends on the temperature and pH of the solution. It was possible to differentiate two working regions: I (for pH < 0.5 and all temperatures) where the film yield tends to zero and II (for approximately 2.0 < pH < 2.8 and temperatures >15 °C) where the film production is maximum. Therefore, the naphthidine electrooxidation mechanism was studied under experimental conditions of region I by cyclic (CV) and square wave voltammetries (SWV) as well as by controlled potential electrolysis.The experimental conditions of region II were chosen to obtain the poly(NAP). The electrochemical response of the film was investigated in pH 1 HClO4 + 0.1 M NaClO4 electrolyte solution by CV and SWV. A plot of Ip,n/fvs. f from SW voltammograms showed the so-called “quasi-reversible maximum”. Formal potential, formal rate constant and anodic transfer coefficient for the surface redox process were also evaluated from the SWV.The poly(NAP) is insoluble in common organic solvents and shows electrochromic behaviour. Its probable structure was determined by FTIR spectroscopy. 相似文献