全文获取类型
收费全文 | 975篇 |
免费 | 34篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 15篇 |
综合类 | 1篇 |
化学工业 | 376篇 |
金属工艺 | 27篇 |
机械仪表 | 21篇 |
建筑科学 | 33篇 |
矿业工程 | 3篇 |
能源动力 | 26篇 |
轻工业 | 140篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
武器工业 | 1篇 |
无线电 | 65篇 |
一般工业技术 | 168篇 |
冶金工业 | 14篇 |
原子能技术 | 8篇 |
自动化技术 | 112篇 |
出版年
2024年 | 2篇 |
2023年 | 7篇 |
2022年 | 66篇 |
2021年 | 80篇 |
2020年 | 22篇 |
2019年 | 26篇 |
2018年 | 27篇 |
2017年 | 26篇 |
2016年 | 44篇 |
2015年 | 29篇 |
2014年 | 43篇 |
2013年 | 72篇 |
2012年 | 63篇 |
2011年 | 64篇 |
2010年 | 43篇 |
2009年 | 42篇 |
2008年 | 42篇 |
2007年 | 36篇 |
2006年 | 27篇 |
2005年 | 26篇 |
2004年 | 26篇 |
2003年 | 16篇 |
2002年 | 24篇 |
2001年 | 6篇 |
2000年 | 8篇 |
1999年 | 10篇 |
1998年 | 8篇 |
1997年 | 12篇 |
1996年 | 14篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 8篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 11篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1971年 | 1篇 |
排序方式: 共有1013条查询结果,搜索用时 0 毫秒
51.
Renata Cegielska-Radziejewska Grzegorz Lesnierowski Tomasz Szablewski Jacek Kijowski 《European Food Research and Technology》2010,231(6):959-964
Lysozyme (N-acetyl-muramyl-hydrolase E.C. 3.2.1.17) is a low-molecular enzyme (14,400 Da) found in body secretions, systemic fluids and tissues of humans and animals. Antibacterial activity of lysozyme monomer is limited first of all to Gram-positive bacteria, which is connected with the structure of the cell wall. This enzyme catalyzes hydrolysis of β-glycoside bonds (1–4), releasing N-acetylglucosamine and N-acetylmuramic acid. The spectrum of antibacterial activity of lysozyme may be extended thanks to modifications of the enzyme. The aim of the study was to assess antibacterial activity, hydrolytic activity and surface hydrophobicity of different forms of lysozyme. Chemical and thermo-chemical modification of lysozyme was performed, and the antibacterial action of lysozyme monomer and modified preparations were compared. It was found that in comparison with monomer and the control, all modified preparations exhibit effective action against Gram (−) bacteria Pseudomonas fluorescens. A particularly effective action was found in case of lysozyme subjected to thermo-chemical modification, which was characterized by the highest proportion of oligomeric forms and the highest hydrophobicity. 相似文献
52.
When time‐series data contain a periodic/seasonal component, the usual block bootstrap procedures are not directly applicable. We propose a modification of the block bootstrap – the generalized seasonal block bootstrap (GSBB) – and show its asymptotic consistency without undue restrictions on the relative size of the period and block size. Notably, it is exactly such restrictions that limit the applicability of other proposals of block bootstrap methods for time series with periodicities. The finite‐sample performance of the GSBB is also illustrated by means of a small simulation experiment. 相似文献
53.
This research presents an analysis of the influence of graphene reinforcement on the thermal and mechanical properties of silicon carbide ceramics, at 2.5% (wt%) graphene content. The SiC composites, containing various carbon nanofillers (graphene oxide and graphene nanoparticles), were sintered by the classical two stage spark plasma sintering method. Two current modes were used, the continuous mode and the pulsed current mode. The results from photothermal radiometry and investigations of the mechanical properties showed that graphene additives significantly improve the thermal properties and toughness of material, sintered from a SiC powder. An 45% growth in the toughness was observed, which increased from 1.21 to 1.75?MPa/m1/2. The thermal diffusivity value also increased from 0.60 to 0.71?cm2/s and giving an improvement in thermal properties of 18%. The friction coefficient reached 7% giving an increase in value from 0.62 to 0.66. Microscopic investigations supported the photothermal radiometry (PTR) results. Whilst, thermal imaging revealed homogeneity of the local thermal properties of the products fabricated from the starting SiC powder. 相似文献
54.
Michal Sitarz Monika Kwoka Elisabetta Comini Dario Zappa Jacek Szuber 《Nanoscale research letters》2014,9(1):43
In this paper we investigate the surface chemistry, including surface contaminations, of SnO2 nanowires deposited on Ag-covered Si substrate by vapor phase deposition (VPD), thanks to x-ray photoelectron spectroscopy (XPS) in combination with thermal desorption spectroscopy (TDS). Air-exposed SnO2 nanowires are slightly non-stoichiometric, and a huge amount of C contaminations is observed at their surface. After the thermal physical desorption (TPD) process, SnO2 nanowires become almost stoichiometric without any surface C contaminations. This is probably related to the fact that C contaminations, as well as residual gases from air, are weakly bounded to the crystalline SnO2 nanowires and can be easily removed from their surface. The obtained results gave us insight on the interpretation of the aging effect of SnO2 nanowires that is of great importance for their potential application in the development of novel chemical nanosensor devices. 相似文献
55.
Acidity and catalytic activity of the mesoporous aluminosilicate molecular sieve MCM-41 总被引:1,自引:0,他引:1
Robert Mokaya William Jones Zhaohua Luan Maria D. Alba Jacek Klinowski 《Catalysis Letters》1996,37(1-2):113-120
The acidity and catalytic properties of aluminosilicate mesoporous molecular sieves with the MCM-41 structure and bulk Si/Al ratios in the 10–60 range have been investigated. The incorporation of 4-coordinate aluminium into the structure of MCM-41 generates both BrØnsted and Lewis acid sites in amounts increasing with the degree of incorporation. However, the BrØnsted/Lewis acid population ratio is independent of the content of aluminium. The number and strength of acid sites generated are comparable to those of a pillared acid-activated clay and lower than in zeolite H-Y with Si/Al=3.65. Aluminosilicate MCM-41 is a moderate catalyst for the conversion of cumene which proceeds predominantly via catalytic cracking to propene and benzene. The sample of MCM-41 with the highest content of framework aluminium (Si/Al=10) has the largest number of BrØnsted acid sites and exhibits highest catalytic activity. 相似文献
56.
Wiktoria Baran Julia Krzemiska Magdalena Szlagor Magdalena Wronka Ewelina Mynarska Beata Franczyk Jacek Rysz 《International journal of molecular sciences》2021,22(18)
Mineralocorticoid receptor antagonists (MRA) are drugs with a potentially broad spectrum of action. They have been reported to have healing effects in many diseases, such as chronic heart failure, hypertension, or nephrotic syndrome. Numerous studies suggest that mineralocorticoid receptor activation is pathogenic and a progression factor of chronic kidney disease (CKD); however, results of studies on the use of MRA in the treatment of CKD are inconclusive. Current guidelines recommend against the use of MRA in patients with advanced CKD. Although, there is growing interest on their use in this population due to treatment benefits. In this review, we summarize studies which were purposed to evaluate the impact of MRA therapy on CKD patients. Despite many benefits of this treatment e.g., reducing cardiovascular mortality or alleviating proteinuria, steroidal MRA (such as spironolactone or eplerenone) have a low safety profile. They often lead to hyperkalemia complications which are dangerous in patients with CKD, and diabetic nephropathy, especially in hemodialysis patients. Studies on recently developed nonsteroidal MRA showed that they have fewer side effects. In our review, we discuss steroidal and nonsteroidal MRA treatment effects on the estimated glomerular filtration rate (eGFR), proteinuria, the cardiovascular system, and hyperkalemia in CKD patients. We present new content and recent publications in this field. 相似文献
57.
Andrzej Wrbel ukasz Zapaa Tomasz Kluz Artur Rogowski Marcin Misiek Kajetan Juszczak Jacek Sieko Daniela Gold Klaudia Stangel-Wjcikiewicz Ewa Poleszak Piotr Radziszewski 《International journal of molecular sciences》2021,22(11)
The purpose of this study was to determine if asiatic acid may act efficiently in the model of cyclophosphamide (CYP)-induced cystitis in rats. We performed experiments after administration of CYP (single dose 200 mg/kg, intraperitoneally), asiatic acid (30 mg/kg/day for 14 consecutive days, by oral gavage), or CYP plus asiatic acid, during which conscious cystometry, measurements of urothelium thickness and bladder edema, as well as selected biomarkers analyses were conducted. In rats that received asiatic acid together with CYP, a drop in bladder basal pressure, detrusor overactivity index, non-voiding contraction amplitude, non-voiding contraction frequency, and the area under the pressure curve were observed, when compared to the CYP group. Furthermore, a significant increase in threshold pressure, voided volume, intercontraction interval, bladder compliance, and volume threshold to elicit NVC were found in that group accordingly. Administration of the asiatic acid successfully restored concentrations of biomarkers both in bladder urothelium (BDNF, CGRP, OCT-3, IL-1β, IL-6, NGF, nitrotyrosine, malondialdehyde, TNF-α, SV2A, SNAP23, SNAP25, PAC-1, ORM1, occludin, IGFBP-3, HB-EGF, T–H protein, Z01, and HPX) and detrusor muscle (Rho kinase and VAChT) in CYP-treated rats. Finally, asiatic acid significantly decreased urothelium thickness and bladder oedema. Asiatic acid proved to be a potent and effective drug in the rat model of CYP-induced cystitis. 相似文献
58.
The article presents the data concerning the synthesis of polythiophene (PTh) nanoparticles in aqueous medium applying emulsion polymerization. The synthetic method was studied in variety of combinations of initiator and surfactant. It was found that application of potassium peroxydisulfate (KPS) as initiator and sodium dodecyl sulfate (SDS) as the surfactant gives the best product yields. The structure, morphology, and physicochemical properties have been analyzed showing that the resulting latex have conducting film forming properties. Resulting polymers were characterized via fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), thermogravimetry‐differential thermal analysis (TG‐DTA), differential scanning calorimetry (DSC), and electrochemical methods [e.g. current–voltage characteristics (I–V), activation energy of electric conductivity, and doping processes]. A mechanism of the polymerization reaction is also discussed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43495. 相似文献
59.
The purpose of the study was to obtain a composite material with the self‐reinforced structure, which processing provide increased mechanical properties. The composites used in presented work were prepared from the two types of fiber mixtures, both were based on polypropylene fibers, the difference was in used cellulose or wood flour filler. Composites were prepared using the hot compaction method. The presented research describes the effect of the composite composition and processing conditions. The results include the static tension measurements, tensile impact tests and thermal analysis, including: DSC and DMTA. The structure has been studies using the SEM observations. Results of presented studies confirm the self‐reinforcing effect in obtained hybrid composites. It provides in the comparison to the standard wood polymer composites to the higher level of material reinforcement with lower amount of natural filler. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43283. 相似文献
60.
Benjamin Bock Anne Schmidt Edyta Sniezek Steffen Dudczig Gert Schmidt Jacek Szczerba Christos G. Aneziris 《Ceramics International》2019,45(4):4499-4508
Since solid, non-metallic inclusions influence considerably the quality of casted steel products, carbon-bonded alumina foam filters are used in secondary metallurgical treatments to remove these particles from steel melts. In order to attain a significant improvement of the filtration process, five different carbonaceous spinel compounds from the Fe-/Mg-/Mn-Al-O systems are applied on carbon-bonded alumina filters in this study and investigated with regard of their filtration efficiency. However, these spinel compounds decompose partially during sintering at 1400?°C under reducing atmosphere, wherefore the resulting coatings contain not only spinel compounds, but also oxidic and metallic components. The subsequent interaction with molten steel leads to the development of multicrystal structures on the filter surface, which stem from interfacial reactions between coating materials, molten steel, and inclusions. As a result of this procedure, a reduction of almost 60% alumina inclusions is measured with the aid of an automatic SEM, whereby spinel compounds from the Fe-Mn-Al-O system achieve highest filtration efficiencies. 相似文献