全文获取类型
收费全文 | 1385篇 |
免费 | 48篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 15篇 |
综合类 | 2篇 |
化学工业 | 386篇 |
金属工艺 | 19篇 |
机械仪表 | 35篇 |
建筑科学 | 63篇 |
矿业工程 | 2篇 |
能源动力 | 39篇 |
轻工业 | 143篇 |
水利工程 | 9篇 |
石油天然气 | 1篇 |
无线电 | 116篇 |
一般工业技术 | 202篇 |
冶金工业 | 96篇 |
原子能技术 | 11篇 |
自动化技术 | 299篇 |
出版年
2024年 | 3篇 |
2023年 | 17篇 |
2022年 | 47篇 |
2021年 | 60篇 |
2020年 | 24篇 |
2019年 | 27篇 |
2018年 | 34篇 |
2017年 | 34篇 |
2016年 | 57篇 |
2015年 | 32篇 |
2014年 | 43篇 |
2013年 | 99篇 |
2012年 | 84篇 |
2011年 | 94篇 |
2010年 | 70篇 |
2009年 | 74篇 |
2008年 | 62篇 |
2007年 | 66篇 |
2006年 | 63篇 |
2005年 | 50篇 |
2004年 | 49篇 |
2003年 | 37篇 |
2002年 | 36篇 |
2001年 | 22篇 |
2000年 | 19篇 |
1999年 | 17篇 |
1998年 | 30篇 |
1997年 | 31篇 |
1996年 | 18篇 |
1995年 | 22篇 |
1994年 | 18篇 |
1993年 | 14篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 9篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1973年 | 2篇 |
1970年 | 2篇 |
1903年 | 1篇 |
排序方式: 共有1438条查询结果,搜索用时 15 毫秒
51.
Cdric H. G. Neutel Jhana O. Hendrickx Wim Martinet Guido R. Y. De Meyer Pieter-Jan Guns 《International journal of molecular sciences》2020,21(23)
Background: Autophagy is a highly conserved catabolic homeostatic process, crucial for cell survival. It has been shown that autophagy can modulate different cardiovascular pathologies, including vascular calcification (VCN). Objective: To assess how modulation of autophagy, either through induction or inhibition, affects vascular and valvular calcification and to determine the therapeutic applicability of inducing autophagy. Data sources: A systematic review of English language articles using MEDLINE/PubMed, Web of Science (WoS) and the Cochrane library. The search terms included autophagy, autolysosome, mitophagy, endoplasmic reticulum (ER)-phagy, lysosomal, calcification and calcinosis. Study characteristics: Thirty-seven articles were selected based on pre-defined eligibility criteria. Thirty-three studies (89%) studied vascular smooth muscle cell (VSMC) calcification of which 27 (82%) studies investigated autophagy and six (18%) studies lysosomal function in VCN. Four studies (11%) studied aortic valve calcification (AVCN). Thirty-four studies were published in the time period 2015–2020 (92%). Conclusion: There is compelling evidence that both autophagy and lysosomal function are critical regulators of VCN, which opens new perspectives for treatment strategies. However, there are still challenges to overcome, such as the development of more selective pharmacological agents and standardization of methods to measure autophagic flux. 相似文献
52.
Roberta D’Ambrosio Alessio Aghemo Raffaele De Francesco Maria Grazia Rumi Enrico Galmozzi Stella De Nicola Cristina Cheroni Paul J. Clark Guido Ronchi Pietro Lampertico Massimo Colombo 《International journal of molecular sciences》2014,15(5):7213-7224
The interleukin 28B (IL28B) rs12979860 polymorphism is associated with treatment outcome in hepatitis C virus (HCV) genotype 1 and 4 patients. Its association with the histological features of chronic hepatitis C and disease severity needs further clarifications. To assess the correlation between IL28B genotype, HCV genotype and liver biopsy findings in untreated patients.
Materials and Methods
Pre-treatment liver biopsies from 335 HCV Caucasian patients (59% males, age 50 years) enrolled in the MIST study were staged for fibrosis and inflammation according to the METAVIR and the Ishak scoring systems; steatosis was dichotomized as <5% or ≥5%. IL28B was typed by Taqman Single Nucleotide Polymorphism (SNP) genotyping assay. HCV genotype was 1 in 151 (45%), 2 in 99 (30%), 3 in 50 (15%) and 4 in 35 (10%) patients. IL28B genotype was CC in 117 (34%), CT in 166 (49%) and TT in 52 (15%). At univariate analysis, the IL28B CC genotype was associated with severe portal inflammation in HCV-1 patients (CC vs. CT/TT: 86% vs. 63%, p = 0.005), severe lobular inflammation in HCV-2 patients (CC vs. CT/TT: 44% vs. 23%, p = 0.03), and less fatty infiltration in HCV-1 patients (CC vs. CT/TT: 72% vs. 51%, p = 0.02). Despite the lack of any association between IL28B and fibrosis stage, in HCV-3 patients IL28B CC correlated with METAVIR F3–F4 (CC vs. CT/TT: 74% vs. 26%, p = 0.05). At multivariate analysis, the genotype CC remained associated with severe portal inflammation in HCV-1, only (Odds Ratio (OR): 95% Confidence Interval (CI): 3.24 (1.23–8.51)). IL28B genotype is associated with the histological features of chronic hepatitis C in a HCV genotype dependent manner, with CC genotype being independently associated with severe portal inflammation. 相似文献53.
Guido Mula Lucy Loddo Elisa Pinna Maria V Tiddia Michele Mascia Simonetta Palmas Roberta Ruffilli Andrea Falqui 《Nanoscale research letters》2014,9(1):332
The results of an investigation on the Er doping of porous silicon are presented. Electrochemical impedance spectroscopy, optical reflectivity, and spatially resolved energy dispersive spectroscopy (EDS) coupled to scanning electron microscopy measurements were used to investigate on the transient during the first stages of constant current Er doping. Depending on the applied current intensity, the voltage transient displays two very different behaviors, signature of two different chemical processes. The measurements show that, for equal transferred charge and identical porous silicon (PSi) layers, the applied current intensity also influences the final Er content. An interpretative model is proposed in order to describe the two distinct chemical processes. The results can be useful for a better control over the doping process.
PACS
81.05.Rm; 82.45.Rr 相似文献54.
As an alternative to previously developed catalytic FeCrAlloy fibre mat burners based on perovskite catalysts, new catalytic burners have been developed based on Pd catalyst on lantana-stabilised Al2O3 and different fibre structures (NIT100A, NIT100S and NIT200S by ACOTECH NV). All development steps are considered, shifting from catalyst preparation (based on combustion synthesis of γ-Al2O3) to the optimisation of lantana and Pd loadings, from the definitions of the best catalyst-deposition conditions (washcoating) to the catalytic burners performances, determined in an ad hoc developed combustion chamber. The results show almost half pollutants emissions and better performance compared to various non-catalytic counterparts, especially as far as CO and NOx emissions are concerned. Some flame instability problems were though registered, especially for one of the catalytic burner mattresses employed, at low specific power inputs and excesses of air (<375 kW/m2 and <12%, respectively). Further, PdO/Pd transition is shown to influence the dynamic behaviour of the catalytic burners. 相似文献
55.
Tiziana Armaroli Maria Bevilacqua Marcella Trombetta Aìda Gutirrez Alejandre Jorge Ramirez Guido Busca 《Applied Catalysis A: General》2001,220(1-2):181-190
The interaction of aromatic hydrocarbons benzene, toluene, o-, m- and p-xylene and of methyl pyridines (in particular 2,6-lutidine) with H-ZSM-5 and H-FER zeolites has been studied. Two different H-ZSM-5 samples with strongly different intensity ratios between the two main OH stretching bands have been used. Benzene, toluene and p-xylene enter easily the cavities and give rise to three different H-bonded complexes. Two of them are strongly bonded while the third is likely a very hindered and distorted one. o-Xylene enters slowly the cavities and m-xylene even more slowly. Faster diffusion occurs at higher temperatures. On the contrary, xylenes do not enter the FER cavities. In spite of its steric hindrance, supposed to be the same of m-xylene, 2,6-lutidine enters fast the ZSM channels and is protonated by the internal sites. On the contrary, it does not enter the FER cavities, but it is protonated too on the external silanols sites. Evidence is provided for some kind of heterogeneity of the internal sites of ZSM-5 zeolite. Additionally, it is concluded that other effects besides the molecular sieving effect may play a role in the access and diffusion of molecules into the zeolite channels. 相似文献
56.
Comparative study on volatile compounds,fatty acids,squalene and quality parameters from whole fruit,pulp and seed oils of two tunisian olive cultivars using chemometrics 下载免费PDF全文
57.
Marcella Trombetta Tiziana Armaroli Aìda Gutirrez Alejandre Horacio Gonzalez Jorge Ramirez Solis Guido Busca 《Catalysis Today》2001,65(2-4):285-292
The interaction of HZSM5 and Mo-ZSM5 with benzene, naphthalene, toluene, ortho-xylene, para-xylene, n-butane, isobutane, n-heptane, and methylcyclohexane, in the range 100–773 K has been investigated using FT-IR spectroscopy. Hydrogen bonded species with the internal bridging and the external terminal OHs has been detected. The reactivity at high temperature has also been studied. The access to the internal cavities and to the strongly acidic OHs is at least partly hindered in the case of Mo-ZSM5. The catalytic activity of ZSM5 was moderated by the addition of molybdenum, with lower cracking and higher liquid yields. 相似文献
58.
Paul P. Van Veldhoven Johannes V. Swinnen Murielle Esquenet Guido Verhoeven 《Lipids》1997,32(12):1297-1300
A protocol, based on the use of Pseudomonas lipase, is presented to measure quantitatively the amount of triacylglycerols in extracts from cultured cells or tissues.
Since the lipase also acts on di- and monoacylglycerols, separation of the extracts by thin-layer chromatography is recommended.
In order to allow the lipase-catalyzed hydrolysis to proceed efficiently, lipid extracts or eluates from silica scraping were
mixed with the detergent Thesit [dodecylpoly(ethylene glycol ether)], prior to drying. After dissolution of the dried residues
in water, the amount of triacylglycerols was quantified using Pseudomonas sp. lipase, glycerol kinase, glycerol-phosphate oxidase, and peroxidase. The activity of the latter enzyme was followed either
colorimetrically in the presence of 4-aminoantipyrine and 2,4,6-tribromo-3-hydroxybenzoic acid or fluorimetrically in the
presence of homovanillic acid. 相似文献
59.
60.
Guido Walther Andreas Martin Angela Köckritz 《Journal of the American Oil Chemists' Society》2013,90(1):141-145
A selection of plant oils was catalytically transferred into 1,19-nonadecanedioate by a direct transesterification, isomerization and methoxycarbonylation under mild conditions using Pd/o-C6H4(CH2P t Bu2)2. Additionally, sulfuric acid was demonstrated as being able to substitute methane sulfonic acid as co-catalyst without any significant loss of activity and selectivity. 相似文献