全文获取类型
收费全文 | 253篇 |
免费 | 9篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 89篇 |
机械仪表 | 5篇 |
建筑科学 | 8篇 |
矿业工程 | 1篇 |
能源动力 | 12篇 |
轻工业 | 40篇 |
水利工程 | 2篇 |
石油天然气 | 3篇 |
无线电 | 8篇 |
一般工业技术 | 44篇 |
冶金工业 | 8篇 |
原子能技术 | 1篇 |
自动化技术 | 39篇 |
出版年
2023年 | 3篇 |
2022年 | 27篇 |
2021年 | 21篇 |
2020年 | 8篇 |
2019年 | 10篇 |
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 8篇 |
2015年 | 6篇 |
2014年 | 14篇 |
2013年 | 12篇 |
2012年 | 18篇 |
2011年 | 28篇 |
2010年 | 22篇 |
2009年 | 13篇 |
2008年 | 13篇 |
2007年 | 6篇 |
2006年 | 10篇 |
2005年 | 9篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1989年 | 1篇 |
排序方式: 共有262条查询结果,搜索用时 0 毫秒
71.
72.
Summary This article analyses the changes in development of journals on social sciences and humanities in Ukraine and shows the results
of the comparative analysis of journals on social sciences and humanities in Ukraine, and journals in the world included in
relevant databases of the US Institute for Scientific Information (Philadelphia). 相似文献
73.
Panayiotis Kolios Vasilis Friderikos Katerina Papadaki 《Mobile Networks and Applications》2012,17(2):267-280
Energy efficiency and capacity maximization are two of the most challenging issues to be addressed by current and future cellular
networks. Significant research effort has been placed recently in reducing the total energy consumption while maintaining
or improving capacity either by introducing more efficient hardware components or by developing innovative software techniques.
In this paper we investigate a novel networking paradigm to address the aforementioned problems. By capitalizing on the inherent
delay tolerance of Internet type services, we argue that significant energy savings can be achieved by postponing the communication
of information for a later time instance with better networking conditions. We device decentralized algorithms for the proposed
postponement schemes and show the superior performance of implementing such schemes over the traditional cellular operation. 相似文献
74.
Microwave‐synthesized magnetic chitosan microparticles for the immobilization of yeast cells 下载免费PDF全文
Ivo Safarik Kristyna Pospiskova Zdenka Maderova Eva Baldikova Katerina Horska Mirka Safarikova 《Yeast (Chichester, England)》2015,32(1):239-243
An extremely simple procedure has been developed for the immobilization of Saccharomyces cerevisiae cells on magnetic chitosan microparticles. The magnetic carrier was prepared using an inexpensive, simple, rapid, one‐pot process, based on the microwave irradiation of chitosan and ferrous sulphate at high pH. Immobilized yeast cells have been used for sucrose hydrolysis, hydrogen peroxide decomposition and the adsorption of selected dyes. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
75.
Cajka T Riddellova K Zomer P Mol H Hajslova J 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2011,28(10):1372-1382
Dithiocarbamates (DTCs) are fungicides that require a specific single-residue method for detection and verification of compliance with maximum residue limits (MRLs) as established for fruit and vegetables in the EU. In this study, the use of ambient mass spectrometry was investigated for specific determination of individual DTCs (thiram, ziram) in fruit. Two complementary approaches have been investigated for their rapid analysis: (i) direct analysis in real time (DART) combined with medium-high resolution/accurate mass time-of-flight mass spectrometry (TOFMS) and high-resolution/accurate mass Orbitrap MS, and (ii) desorption electrospray ionization (DESI) combined with tandem-in-time mass spectrometry (MS(2)). With both techniques, thiram deposited on a glass surface (DART) or Teflon (DESI) could be directly detected. With DART, this was also possible for ziram. Before the instrumental analysis of fruit matrix, an extract had to be prepared following a straightforward procedure. The raw extracts were deposited on a slide (DESI), or rods were dipped into the extracts (DART), after which thiram and ziram could be rapidly detected (typically 10 samples in a few minutes). In the case of thiram, the lowest calibration levels were 1?mg?kg(-1) (DART-TOFMS, DESI-MS(2)) and 0.1?mg?kg(-1) (DART-Orbitrap MS). For ziram, the achieved lowest calibration levels were 0.5?mg?kg(-1) (DART-TOFMS) and 1?mg?kg(-1) (DART-Orbitrap MS). In all cases, this was sufficiently low to test samples against EU-MRLs for a number of fruit crops. Using an internal standard, (semi)quantitative results could be obtained. 相似文献
76.
Aifantis KE Shrivastava S Odegard GM 《Journal of materials science. Materials in medicine》2011,22(6):1375-1381
The mechanical properties of collagenous tissues, such as tendon and ligaments, are of particular interest as they are found
extensively in the human body. In the present study the transverse mechanical properties of collagen fibers are reported for
the first time. The elastic modulus was found to be 63 ± 4 MPa, while the viscosity was estimated to be
14 \textGPa £ h £ 56 \textGPa \texts 14\;{\text{GPa}} \le \eta \le 56\;{\text{GPa}}\;{\text{s}} . Comparison with similar data in the literature, for bulk tendon and collagen fibrils, suggests that the apparent modulus
of a network of interconnected building blocks is reduced as compared to the modulus of the individual building blocks; in
particular E
tendon < E
fiber < E
fibril; this is due to the fact that as the scale of the microstructure increases (i) slippage and sliding between the respective
building blocks (fibrils or fibers) increases, (ii) the volume fraction of the stiff collagen proteins decreases. 相似文献
77.
Lübcke-von Varel U Machala M Ciganek M Neca J Pencikova K Palkova L Vondracek J Löffler I Streck G Reifferscheid G Flückiger-Isler S Weiss JM Lamoree M Brack W 《Environmental science & technology》2011,45(6):2384-2390
Sediment extracts from three polluted sites of the river Elbe basin were fractionated using a novel online fractionation procedure. Resulting fractions were screened for mutagenic, aryl hydrocarbon receptor (AhR)-mediated, transthyretin (TTR)-binding, and estrogenic activities and their potency to inhibit gap junctional intercellular communication (GJIC) to compare toxicity patterns and identify priority fractions. Additionally, more than 200 compounds and compound classes were identified using GC-MS/MS, LC-MS/MS, and HPLC-DAD methods. For all investigated end points, major activities were found in polar fractions, which are defined here as fractions containing dominantly compounds with at least one polar functional group. Nonpolar PAH fractions contributed to mutagenic and AhR-mediated activities while inhibition of GJIC and estrogenic and TTR-binding activities were exclusively observed in the polar fractions. Known mutagens in polar fractions included nitro- and dinitro-PAHs, azaarenes, and keto-PAHs, while parent and monomethylated PAHs such as benzo[a]pyrene and benzofluoranthenes were identified in nonpolar fractions. Additionally, for one sample, high AhR-mediated activities were determined in one fraction characterized by PCDD/Fs, PCBs, and PCNs. Estrone, 17β-estradiol, 9H-benz[de]anthracen-7-one, and 4-nonylphenol were identified as possible estrogenic and TTR-binding compounds. Thus, not only nonpolar compounds such as PAHs, PCBs, and PCDD/Fs but also the less characterized and investigated more polar substances should be considered as potent mutagenic, estrogenic, AhR-inducing, TTR-binding, and GJIC-inhibiting components for future studies. 相似文献
78.
Alkali (NaOH)-based compounds are commonly used in the food industry to clean food contact surfaces. However, little information is available on the ability of alkali and alkali-based cleaning compounds to remove extracellular polymeric substances (EPS) produced by biofilm bacteria. The objectives of this study were to determine the temperature and NaOH concentration necessary to remove biofilm EPS from stainless steel under turbulent flow conditions (clean-in-place simulation) and to determine the ability of a commercial alkaline cleaner to remove biofilm EPS from stainless steel when applied under static conditions without heat. Biofilms were produced by growing Pseudomonas putida on stainless steel for 72 h at 25 degrees C in a 1:10 dilution of Trypticase soy broth. The biofilms were treated using NaOH at concentrations of 1.28 to 6.0% and temperatures ranging from 66 to 70 degrees C. Other biofilms were treated with commercial alkaline cleaner at 25 or 4 degrees C for 1 to 30 min. Removal of EPS was determined by direct microscopic observation of samples stained with fluorescent-labeled peanut agglutinin lectin. Treatment with 1.2% NaOH at 66 degrees C for 3 min was insufficient to remove biofilm EPS. A minimum of 2.5% NaOH at 66 degrees C and 2.0% NaOH at 68 degrees C for 3 min were both effective for EPS removal. Commercial alkaline cleaner removed over 99% of biofilm EPS within 1 min at 4 and 25 degrees C under static conditions. Selection of appropriated cleaning agent formulation and use at recommended concentrations and temperatures is critical for removal of biofilm EPS from stainless steel. 相似文献
79.
Viola Kolaíkov Katerina Brodsky Lucie Petrskov Helena Pelantov Josef Cva
ka Libor Havlí
ek Vladimír Ken Kateina Valentov 《International journal of molecular sciences》2022,23(23)
Phenolic acids are known flavonoid metabolites, which typically undergo bioconjugation during phase II of biotransformation, forming sulfates, along with other conjugates. Sulfated derivatives of phenolic acids can be synthesized by two approaches: chemoenzymatically by 3′-phosphoadenosine-5′-phosphosulfate (PAPS)-dependent sulfotransferases or PAPS-independent aryl sulfotransferases such as those from Desulfitobacterium hafniense, or chemically using SO3 complexes. Both approaches were tested with six selected phenolic acids (2-hydroxyphenylacetic acid (2-HPA), 3-hydroxyphenylacetic acid (3-HPA), 4-hydroxyphenylacetic acid (4-HPA), 3,4-dihydroxyphenylacetic acid (DHPA), 3-(4-hydroxyphenyl)propionic acid (4-HPP), and 3,4-dihydroxyphenylpropionic acid (DHPP)) to create a library of sulfated metabolites of phenolic acids. The sulfates of 3-HPA, 4-HPA, 4-HPP, DHPA, and DHPP were all obtained by the methods of chemical synthesis. In contrast, the enzymatic sulfation of monohydroxyphenolic acids failed probably due to enzyme inhibition, whereas the same reaction was successful for dihydroxyphenolic acids (DHPA and DHPP). Special attention was also paid to the counterions of the sulfates, a topic often poorly reported in synthetic works. The products obtained will serve as authentic analytical standards in metabolic studies and to determine their biological activity. 相似文献
80.
Gheorghi VISSOKOV Katerina ZAHARIEVA 《等离子体科学和技术》2007,9(5):603-610
We discuss the plasma-chemical synthesis and the properties of transition metals oxides, Al2O3, SiO2, rare-earth oxides, oxides for ceramics and metal-ceramics, and oxides used as catalysts. Bearing in mind the indisputable advantages of using plasma-chemically synthesized nanodispersed oxides for the needs of various industrial fields, we set out to review the articles published in the past few years devoted to the problems of plasma-chemical synthesis and characterization of nanodispersed oxides. 相似文献