全文获取类型
收费全文 | 1211篇 |
免费 | 98篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 16篇 |
综合类 | 2篇 |
化学工业 | 357篇 |
金属工艺 | 21篇 |
机械仪表 | 24篇 |
建筑科学 | 30篇 |
能源动力 | 55篇 |
轻工业 | 183篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 110篇 |
一般工业技术 | 222篇 |
冶金工业 | 36篇 |
原子能技术 | 5篇 |
自动化技术 | 246篇 |
出版年
2024年 | 2篇 |
2023年 | 33篇 |
2022年 | 90篇 |
2021年 | 114篇 |
2020年 | 46篇 |
2019年 | 45篇 |
2018年 | 72篇 |
2017年 | 59篇 |
2016年 | 68篇 |
2015年 | 57篇 |
2014年 | 57篇 |
2013年 | 107篇 |
2012年 | 91篇 |
2011年 | 99篇 |
2010年 | 65篇 |
2009年 | 67篇 |
2008年 | 54篇 |
2007年 | 45篇 |
2006年 | 35篇 |
2005年 | 20篇 |
2004年 | 22篇 |
2003年 | 15篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 9篇 |
1996年 | 8篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
排序方式: 共有1313条查询结果,搜索用时 15 毫秒
991.
Annalisa Lucera Amalia Conte Matteo Alessandro Del Nobile 《International Journal of Food Science & Technology》2011,46(11):2351-2357
To reduce quality loss of fresh‐cut green beans, different packaging systems were studied. In particular, samples were packaged in micro‐perforated and no‐perforated films and stored at 5 °C; unpackaged fresh‐cut green beans were also stored at the same temperature as the control. Headspace gas concentrations, mass loss, sensory quality and microbial proliferation were monitored for about 3 weeks. Results confirmed that selection of proper packaging is of crucial importance to create conditions able to guarantee the maintenance of product quality. Shelf life of fresh‐cut green beans packaged in the no‐perforated film (polyethylene, 25 μm) and in two micro‐perforated films (polypropylene films with 7 and 4 micro‐holes per package) was higher (19.2, 18.13 and 17.7 days, respectively) than that of the control or samples packaged in the micro‐perforated film with 12 micro‐holes per package (16.5 days). 相似文献
992.
A recent pharmacognostic survey on the European food market highlighted a previously unreported adulteration of Mediterranean oregano. Dried crushed leaves, silvery grey in colour but devoid of glandular hairs and with unequivocal xerophytic adaptations were copiously spotted (20–30% w/w) in a number of commercial samples. Microscopical investigations narrowed the range of suspect candidates to Olea europaea L. and a method based on Sequence-Characterised Amplified Regions markers (SCARs) was developed from Random Amplified Polymorphic DNA markers (RAPDs) specific for O. europaea, in order to authenticate the contaminant and set up a fast, sensitive, reliable and low-cost screening of dried commercial Mediterranean oregano samples. The method enabled the unequivocal detection of low amounts (up to 1%) of olive leaves in both artificial and commercial batches, allowing the preemptive rejection of suspect samples and reducing the number of samples to be subjected to more careful pharmacognostic analyses. The relatively short dimension of the amplicons is suitable for the analysis of potentially degraded DNA obtained from dried and processed commercial plant material and given their specificity the method may be enforceable also in case of forensic disputes even in case of finely ground material. 相似文献
993.
994.
995.
引言达涅利(Danieli)最新推出的新型宽板轧机机组用于满足现代化钢厂多项关键的要求,其中包括较高生产率和收得率、严格的尺寸公差、良好的力学性能以及较高表面质量等.达涅利(Danieli)为中东地区提供的新型宽板轧机机组提供了工艺设备和相关自动化电气设备,其中包括以下主要技术领域: 相似文献
996.
997.
Anna L. Guildford Helen J. S. Stewart Christopher Morris Matteo Santin 《Journal of the Royal Society Interface》2011,8(58):641-649
In-stent restenosis is a clinical complication following coronary angioplasty caused by the implantation of the metal device in the atherosclerotic vessel. Histological examination has shown a clear contribution of both inflammatory and smooth muscle cells (SMCs) to the deposition of an excess of neointimal tissue. However, the sequence of events leading to clinically relevant restenosis is unknown. This paper aims to study the phenotype of SMCs when adhering on substrates and exposed to biochemical stimuli typical of the early phases of stent implantation. In particular, human SMC phenotype was studied when adhering on extracellular matrix-like material (collagen-rich gel), thrombus-like material (fibrin gel) and stent material (stainless steel) in the presence or absence of a platelet-derived growth factor (PDGF) stimulus. Cells on the collagen and fibrin-rich substrates maintained their contractile phenotype. By contrast, cells on stainless steel acquired a secretory phenotype with a proliferation rate 50 per cent higher than cells on the natural substrates. Cells on stainless steel also showed an increase in PDGF-BB receptor expression, thus explaining the increase in proliferation observed when cells were subject to PDGF-BB stimuli. The stainless steel substrate also promoted a different pattern of β1-integrin localization and an altered expression of hyaluronan (HA) synthase isoforms where the synthesis of high-molecular-weight HA seemed to be favoured. These findings highlighted the induction of a phenotypic pattern in SMC by the stainless steel substrate whereby the formation of a HA-rich neointimal tissue is enhanced. 相似文献
998.
In this work, oedometer tests were used to examine the effects of ethanol-gasoline blends on the consolidation characteristics of a kaolinitic soil from northwestern Spain. As the fraction of ethanol in blends increases, the equivalent liquid limit of soil decreases, showing a dividing point for blends containing about 85% of ethanol. By means of a database of compression indexes of remolded clayey soils mixed with differing kinds of alcohol and petroleum hydrocarbon contaminants, a multivariable model for estimating the compression index of the contaminated soil is presented, on the basis of the virgin compression index, normalized liquid limit, and normalized pore fluid viscosity. The model is valid only for percentages of active clays up to 10–15% in weight in kaolinitic soil. The authors would like to encourage others to further validate and refine the approach, which may be useful for preliminary estimation of the compression index of contaminated soils, reducing operators’ risk of inhaling vapors released by the ethanol-gasoline blends while performing the test and also reducing damage to conventional oedometer equipment. 相似文献
999.
Cristina Costa Annalisa Lucera Marcella Mastromatteo Amalia Conte Matteo Alessandro Del Nobile 《International Journal of Food Science & Technology》2010,45(8):1545-1551
In this work, the combined effects of chitosan, modified atmosphere packaging (MAP) and packaging barrier properties on shelf life of fresh pasta is presented. In particular, all pasta samples were packaged under active and passive MAP in two different polymeric films with high and low barrier properties. In order to assess the influence of the variables described beforehand on the shelf life of pasta, the sensorial and microbiological quality has been monitored during storage. Results confirmed the antimicrobial properties of chitosan. Moreover, the findings recorded in this study suggest that the shelf life of fresh pasta is limited by the sensorial characteristics. Statistically significant differences between the shelf life of pasta packaged in low barrier and high barrier films were found. The best result was obtained for samples packaged in high barrier film, due to the ability of the packaging to maintain the gas headspace conditions during the storage. 相似文献
1000.
Matteo Bocci Clara Oudenaarden Xavier Senz-Sard Joel Simrn Arvid Edn Jonas Sjlund Christina Mller Magnus Gissln Henrik Zetterberg Elisabet Englund Kristian Pietras 《International journal of molecular sciences》2021,22(21)
A wide range of neurological manifestations have been associated with the development of COVID-19 following SARS-CoV-2 infection. However, the etiology of the neurological symptomatology is still largely unexplored. Here, we used state-of-the-art multiplexed immunostaining of human brains (n = 6 COVID-19, median age = 69.5 years; n = 7 control, median age = 68 years) and demonstrated that expression of the SARS-CoV-2 receptor ACE2 is restricted to a subset of neurovascular pericytes. Strikingly, neurological symptoms were exclusive to, and ubiquitous in, patients that exhibited moderate to high ACE2 expression in perivascular cells. Viral dsRNA was identified in the vascular wall and paralleled by perivascular inflammation, as signified by T cell and macrophage infiltration. Furthermore, fibrinogen leakage indicated compromised integrity of the blood–brain barrier. Notably, cerebrospinal fluid from additional 16 individuals (n = 8 COVID-19, median age = 67 years; n = 8 control, median age = 69.5 years) exhibited significantly lower levels of the pericyte marker PDGFRβ in SARS-CoV-2-infected cases, indicative of disrupted pericyte homeostasis. We conclude that pericyte infection by SARS-CoV-2 underlies virus entry into the privileged central nervous system space, as well as neurological symptomatology due to perivascular inflammation and a locally compromised blood–brain barrier. 相似文献