全文获取类型
收费全文 | 4076篇 |
免费 | 217篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 61篇 |
综合类 | 1篇 |
化学工业 | 814篇 |
金属工艺 | 86篇 |
机械仪表 | 71篇 |
建筑科学 | 80篇 |
矿业工程 | 10篇 |
能源动力 | 109篇 |
轻工业 | 494篇 |
水利工程 | 33篇 |
石油天然气 | 14篇 |
无线电 | 235篇 |
一般工业技术 | 504篇 |
冶金工业 | 1394篇 |
原子能技术 | 22篇 |
自动化技术 | 369篇 |
出版年
2024年 | 6篇 |
2023年 | 34篇 |
2022年 | 66篇 |
2021年 | 144篇 |
2020年 | 105篇 |
2019年 | 108篇 |
2018年 | 129篇 |
2017年 | 132篇 |
2016年 | 141篇 |
2015年 | 88篇 |
2014年 | 100篇 |
2013年 | 237篇 |
2012年 | 175篇 |
2011年 | 199篇 |
2010年 | 162篇 |
2009年 | 161篇 |
2008年 | 150篇 |
2007年 | 118篇 |
2006年 | 94篇 |
2005年 | 61篇 |
2004年 | 64篇 |
2003年 | 73篇 |
2002年 | 53篇 |
2001年 | 44篇 |
2000年 | 41篇 |
1999年 | 62篇 |
1998年 | 383篇 |
1997年 | 287篇 |
1996年 | 175篇 |
1995年 | 101篇 |
1994年 | 84篇 |
1993年 | 106篇 |
1992年 | 21篇 |
1991年 | 26篇 |
1990年 | 19篇 |
1989年 | 32篇 |
1988年 | 16篇 |
1987年 | 17篇 |
1986年 | 19篇 |
1985年 | 20篇 |
1984年 | 12篇 |
1983年 | 18篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 17篇 |
1979年 | 5篇 |
1978年 | 12篇 |
1977年 | 55篇 |
1976年 | 92篇 |
1973年 | 3篇 |
排序方式: 共有4297条查询结果,搜索用时 125 毫秒
181.
Partial replacement of EPDM by GTR in thermoplastic elastomers based on PP/EPDM: Effects on morphology and mechanical properties
下载免费PDF全文
![点击此处可从《应用聚合物科学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The formulation of recycled thermoplastic elastomeric materials (TPE) based on ground tyre rubber (GTR), generated from end of life tyres, can be an alternative strategy to deal with a type of waste responsible for increasingly environmental problems over the past decades. The incompatibility of GTR with thermoplastics places several issues on the formulation of these materials, which this study tries to overcome. An encapsulation strategy of the GTR by an elastomeric phase is proposed in this work to overcome the lack of adhesion between the materials. Ternary blends, composed of a highly flowable polypropylene homopolymer, an ethylene propylene diene monomer (EPDM) and GTR were formulated and their morphology and mechanical properties analyzed. The morphology of the blends showed interaction between the materials, revealing that the encapsulation of GTR by a rubber phase can be an adequate strategy to formulate recycled‐based TPE materials, if the dimension of the GTR particles is controlled and taken into consideration. The mechanical properties revealed the replacement effect of EPDM by GTR, and its dependence on the amount of that replacement. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40160. 相似文献
182.
Gerson Reginaldo Marques Soraia Vilela Borges Diego Alvarenga Botrel Joyce Maria Gomes da Costa Eric Keven Silva Jefferson Luiz Gomes Corrêa 《Drying Technology》2014,32(7):861-868
Maize (Zea mays) is a cereal grown in Brazil, and its availability is limited to the harvest season. An alternative processing route is based on the production of green corn powder, which has a longer shelf-life and increased versatility. This study aimed to evaluate the influence of drying conditions on the physical characteristics, size, and morphology of green corn powder. Drying experiments were performed on a spray dryer according to a central composite rotational design to evaluate inlet air temperature, feed flow rate, and pulp concentration. The yield of dried pulp corn had an average value of 36.19%. The following mean values for the physical properties of the powder were measured: solubility of 94.37 g/100 g, wettability of 128.05 seconds, moisture content of 1.97%, water activity of 0.13, density of 0.79 g/mL, and a particle diameter of 31.02 µm. The powder was also yellow with less intensity, and the particle surface was smooth at higher temperatures and had a tendency to form agglomerates. The estimated optimal conditions for spray drying were 48% (w/w) pulp concentration, 172°C inlet air temperature, and feed flow rate of 0.56 L/h. 相似文献
183.
Camilla Costa Renzo Di Felice Paolo Moretti Maddalena Oliva Rouzbeh Ramezani 《加拿大化工杂志》2020,98(12):2516-2529
This work is a companion to a previous article, Part I, published in The Canadian Journal of Chemical Engineering, dealing with CO2 absorption in aqueous solutions containing a single aminic reagent (specifically methyldiethanolamine (MDEA) or piperazine (PZ)). In this second part, different PZ/MDEA mixtures are experimentally studied and their performances are compared with that of the single reagents. It is indeed well known that small quantities of PZ added to MDEA aqueous solutions are sufficient to obtain a significant improvement in the kinetics of the process. PZ is considered an activator or promoter for MDEA, but the mechanism of this synergy has still not been clearly demonstrated. The aim of this study is an attempt to understand how PZ and MDEA can interact by experimentally analyzing this beneficial mutual effect and by explaining it with the help of a suitable yet not complex model. We believe that the involved chemistry is not more complex than that reported in Part I for the single reagents. According to our findings, it is MDEA that enhances the action of PZ, as opposed to what many authors claim. Moreover, our results seem to rule out the existence of any PZ shuttle effect. 相似文献
184.
Alessia Costa Barbara Rani Thomaz F. S. Bastiaanssen Francesco Bonfiglio Eoin Gunnigle Gustavo Provensi Moira Rossitto Marcus Boehme Conall Strain Clara S. Martínez Patrizio Blandina John F. Cryan Sophie Lay Renato Corradetti Maria Beatrice Passani 《International journal of molecular sciences》2022,23(2)
Exposure to repeated social stress may cause maladaptive emotional reactions that can be reduced by healthy nutritional supplementation. Histaminergic neurotransmission has a central role in orchestrating specific behavioural responses depending on the homeostatic state of a subject, but it remains to be established if it participates in the protective effects against the insults of chronic stress afforded by a healthy diet. By using C57BL/6J male mice that do not synthesize histamine (Hdc−/−) and their wild type (Hdc+/+) congeners we evaluated if the histaminergic system participates in the protective action of a diet enriched with polyunsaturated fatty acids and vitamin A on the deleterious effect of chronic stress. Behavioural tests across domains relevant to cognition and anxiety were performed. Hippocampal synaptic plasticity, cytokine expression, hippocampal fatty acids, oxylipins and microbiota composition were also assessed. Chronic stress induced social avoidance, poor recognition memory, affected hippocampal long-term potentiation, changed the microbiota profile, brain cytokines, fatty acid and oxylipins composition of both Hdc−/− and Hdc+/+ mice. Dietary enrichment counteracted stress-induced deficits only in Hdc+/+ mice as histamine deficiency prevented almost all the diet-related beneficial effects. Interpretation: Our results reveal a previously unexplored and novel role for brain histamine as a mediator of many favorable effects of the enriched diet. These data present long-reaching perspectives in the field of nutritional neuropsychopharmacology. 相似文献
185.
Flvia Melo Cunha de Pinho Pessoa Caio Bezerra Machado Emerson Lucena da Silva Laudreísa da Costa Pantoja Rodrigo Monteiro Ribeiro Maria Elisabete Amaral de Moraes Manoel Odorico de Moraes Filho Raquel Carvalho Montenegro Andr Salim Khayat Caroline Aquino Moreira-Nunes 《International journal of molecular sciences》2022,23(7)
The increasing numbers of cancer cases worldwide and the exceedingly high mortality rates of some tumor subtypes raise the question about if the current protocols for cancer management are effective and what has been done to improve upon oncologic patients’ prognoses. The traditional chemo-immunotherapy options for cancer treatment focus on the use of cytotoxic agents that are able to overcome neoplastic clones’ survival mechanisms and induce apoptosis, as well as on the ability to capacitate the host’s immune system to hinder the continuous growth of malignant cells. The need to avert the highly toxic profiles of conventional chemo-immunotherapy and to overcome the emerging cases of tumor multidrug resistance has fueled a growing interest in the field of precision medicine and targeted molecular therapies in the last couple of decades, although relatively new alternatives in oncologic practices, the increased specificity, and the positive clinical outcomes achieved through targeted molecular therapies have already consolidated them as promising prospects for the future of cancer management. In recent years, the development and application of targeted drugs as tyrosine kinase inhibitors have enabled cancer treatment to enter the era of specificity. In addition, the combined use of targeted therapy, immunotherapy, and traditional chemotherapy has innovated the standard treatment for many malignancies, bringing new light to patients with recurrent tumors. This article comprises a series of clinical trials that, in the past 5 years, utilized kinase inhibitors (KIs) as a monotherapy or in combination with other cytotoxic agents to treat patients afflicted with solid tumors. The results, with varying degrees of efficacy, are reported. 相似文献
186.
V.S.T. Saito T.F. dos Santos C.G. Vinderola C. Romano J.R. Nicoli L.S. Araújo M.M. Costa J.L. Andrioli A.P.T. Uetanabaro 《Journal of food science》2014,79(2):M208-M213
To study the potential probiotic characteristics such as decrease of pH, microbial viability, and tolerance to simulated digestive steps of fermented soy beverage (“soy yogurt”) produced with lactobacilli isolated from cocoa fermentation (Lactobacillus fermentum TcUESC01 and Lactobacillus plantarum TcUESC02) during fermentation and refrigerated storage. The sensory acceptance of the yogurts was also tested. Samples of soy yogurt produced with L. fermentum TcUESC01 or L. plantarum TcUESC02 were collected during fermentation (0, 4, 8, and 12 h) and refrigerated storage (1, 9, 18, and 27 d), and submitted to pH and bacterial viability determinations. Tolerance to simulated digestion steps was done with refrigerated storage samples at 9 °C. Simulated digestion was performed in 3 successive steps: exposure to pepsin‐HCl solution, bile shock, and simulated small intestinal juice. During storage, a decrease in pH and lactobacillus viability was observed. L. fermentum TcUESC01 showed to be more resistant than L. plantarum TcUESC02 to simulated gastrointestinal digestion. All soy yogurts showed acceptable hedonic scores (greater than 5 in a 9‐point hedonic scale ranging from “like extremely” to “dislike extremely”) in sensory evaluation for flavor, aroma, color, consistency, and overall impression. L. plantarum TcUESC02 and, especially, L. fermentum TcUESC01 showed potential probiotic characteristics when considering pH, cell viability, and tolerance to simulated digestive steps and did not affect the sensory characteristics when supplemented to soy yogurt during storage. 相似文献
187.
Raquel Rodríguez‐Solana Jorge Dias Carlier Maria Clara Costa Anabela Romano 《Journal of the Institute of Brewing》2018,124(3):300-309
Carob pod, fig and almond liqueurs are produced in various Mediterranean regions. This work reports the mineral content of these traditional beverages and evaluates the influence of the raw material. Twenty‐five fruit liqueurs from 16 producers were analysed. A simple open‐vessel sample mineralization by wet digestion using nitric acid–hydrogen peroxide (1:1) was used before spectrometric analysis. Nine essential elements (Cu, Ca, Mg, Na, K, Fe, Zn, Mn and P) and two non‐essentials (Cd and Pb) were quantified by microwave plasma–atomic emission spectrometry (MP‐AES). Carob liqueur presented the broader profile of minerals and was the only fruit liqueur containing iron (72.7% of samples), phosphorous, manganese and low levels of lead (in two of the 11 samples). Conversely, almond liqueurs contained the lowest mineral content with only five elements detected. Fruit liqueurs showed variability in mineral content even within the same liqueur, presumably as a consequence of the different manufacturing processes. Despite this variability, application of principal component analysis to essential mineral concentrations (K, Na, Ca, Mg, Mn, Fe and Zn) resulted in satisfactory classification (PC1 and PC2 accounting for 78.5% of the total variance) of the Portuguese liqueurs evaluated. Copyright © 2018 The Institute of Brewing & Distilling 相似文献
188.
Supervised Multivariate Analysis of Hyper-spectral NIR Images to Evaluate the Starch Index of Apples 总被引:4,自引:0,他引:4
Paolo Menesatti Angelo Zanella Stefano D’Andrea Corrado Costa Graziella Paglia Federico Pallottino 《Food and Bioprocess Technology》2009,2(3):308-314
Fruit maturity indexes are crucial in harvest time determination and commercial context. The harvest time of apples, matching
the desired commercial characteristics, is assessed through starch–iodine test in practice. Fruit halves are dipped into iodine
solution and patterns are visually evaluated by experts comparing them to reference charts. Aim of the work was to study the
relationships of near infrared (NIR) spectral images (1,000–1,700 nm), starch/starch-free patterns visually assessed and RGB
color images. Spectral images of 88 Golden Delicious Klon B apples were sampled at seven different maturity stages. Partial
least-squares discriminant analysis (PLSDA) technique was used on hyper-spectral NIR images to classify single pixels using
its NIR reflectance spectrum. The response variable (i.e. the classification for each pixel) was identified through the matching
of single pixel obtained with the color images, segmented in two classes (starch and starch-free), and the NIR hyper-spectral
matrix. Mean hyper-spectral classification obtained through PLSDA modeling on individual apple correctly classified 80.81%
of the total pixels, while the unique model, i.e. a single model including all the fruits, resulted in 66.33%. In the latter
case, the relationship with the RGB classification showed high values (Pearson correlation coefficient r = 0.95). The present work shows the feasibility of NIR imaging spectroscopy as a tool for apple fruit maturity determination,
avoiding expert’s subjective interpretation by traditional starch index assignments. 相似文献
189.
Desirrê Morais Dias Neuza Maria Brunoro Costa Marilia Regini Nutti Elad Tako Hércia Stampini Duarte Martino 《Critical reviews in food science and nutrition》2018,58(13):2136-2146
ABSTRACTBiofortification aims to improve the micronutrient concentration of staple food crops through the best practices of breeding and modern biotechnology. However, increased zinc and iron concentrations in food crops may not always translate into proportional increases in absorbed zinc (Zn) and iron (Fe). Therefore, assessing iron and zinc bioavailability in biofortified crops is imperative to evaluate the efficacy of breeding programs. This review aimed to investigate the advantages and limitations of in vitro and in vivo methods of iron and zinc bioavailability evaluation in the assessment of biofortification program effectiveness. In vitro, animal and isotopic human studies have shown high iron and zinc bioavailability in biofortified staple food crops. Human studies provide direct knowledge regarding the effectiveness of biofortification, however, human studies are time consuming and are more expensive than in vitro and animal studies. Moreover, in vitro studies may be a useful preliminary screening method to identify promising plant cultivars, however, these studies cannot provide data that are directly applicable to humans. None of these methods provides complete information regarding mineral bioavailability, thus, a combination of these methods should be the most appropriate strategy to investigate the effectiveness of zinc and iron biofortification programs. 相似文献
190.
Anay Priscilla David de Oliveira Mateus Matiuzzi da Costa Daniel Maia Nogueira Francesca Silva Dias 《International Journal of Dairy Technology》2020,73(2):345-356
Twenty isolates from milk and goat cheese were confirmed as Staphylococcus aureus. These isolates were characterised for phenotypic properties related to cell adhesion and for the presence of enterotoxin production, intercellular adhesion and β‐lactam resistance genes. Staphylococcus aureus L47 showed cell adhesion ability and positivity for the sec, sed, icaD, mecA and blaZ genes. Three antimicrobial compounds were tested singly or in pairs for growth control of strain L47: gallic acid (GA), nisin and essential oil (EO) of Croton heliotropiifolius (velame). At 24 h, EO and EO + nisin showed higher inhibitory activity against S. aureus L47 in goat milk. 相似文献