全文获取类型
收费全文 | 2679篇 |
免费 | 132篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 28篇 |
化学工业 | 810篇 |
金属工艺 | 56篇 |
机械仪表 | 80篇 |
建筑科学 | 91篇 |
矿业工程 | 21篇 |
能源动力 | 85篇 |
轻工业 | 195篇 |
水利工程 | 18篇 |
石油天然气 | 8篇 |
武器工业 | 1篇 |
无线电 | 220篇 |
一般工业技术 | 521篇 |
冶金工业 | 167篇 |
原子能技术 | 33篇 |
自动化技术 | 489篇 |
出版年
2023年 | 31篇 |
2022年 | 121篇 |
2021年 | 116篇 |
2020年 | 86篇 |
2019年 | 65篇 |
2018年 | 97篇 |
2017年 | 100篇 |
2016年 | 97篇 |
2015年 | 92篇 |
2014年 | 128篇 |
2013年 | 207篇 |
2012年 | 154篇 |
2011年 | 179篇 |
2010年 | 132篇 |
2009年 | 124篇 |
2008年 | 134篇 |
2007年 | 102篇 |
2006年 | 89篇 |
2005年 | 82篇 |
2004年 | 59篇 |
2003年 | 56篇 |
2002年 | 49篇 |
2001年 | 30篇 |
2000年 | 28篇 |
1999年 | 28篇 |
1998年 | 41篇 |
1997年 | 25篇 |
1996年 | 18篇 |
1995年 | 25篇 |
1994年 | 24篇 |
1993年 | 22篇 |
1992年 | 15篇 |
1991年 | 16篇 |
1990年 | 12篇 |
1989年 | 13篇 |
1988年 | 11篇 |
1987年 | 24篇 |
1986年 | 15篇 |
1985年 | 15篇 |
1984年 | 13篇 |
1983年 | 9篇 |
1982年 | 16篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1976年 | 10篇 |
1975年 | 9篇 |
1974年 | 7篇 |
1973年 | 13篇 |
1972年 | 8篇 |
排序方式: 共有2823条查询结果,搜索用时 15 毫秒
71.
Ivan Rodero David Villegas Norman Bobroff Yanbin Liu Liana Fong S. Masoud Sadjadi 《Journal of Grid Computing》2013,11(2):311-336
The goal of Grid computing is to integrate the usage of computer resources from cooperating partners in the form of Virtual Organizations (VO). One of its key functions is to match jobs to execution resources efficiently. For interoperability between VOs, this matching operation occurs in resource brokering middleware, commonly referred to as the meta-scheduler or meta-broker. In this paper, we present an approach to a meta-scheduler architecture, combining hierarchical and peer-to-peer models for flexibility and extensibility. Interoperability is further promoted through the introduction of a set of protocols, allowing meta-schedulers to maintain sessions and exchange job and resource state using Web Services. Our architecture also incorporates a resource model that enables an efficient resource matching across multiple Virtual Organizations, especially where the compute resources and state are dynamic. Experiments demonstrate these new functional features across three distributed organizations (BSC, FIU, and IBM), that internally use different job scheduling technologies, computing infrastructure and security mechanisms. Performance evaluations through actual system measurements and simulations provide the insights on the architecture’s effectiveness and scalability. 相似文献
72.
Kristopher Page Michael Wilson Nicola J. Mordan Wojciech Chrzanowski Jonathan Knowles Ivan P. Parkin 《Journal of Materials Science》2011,46(19):6355-6363
The adhesion of Staphylococcus aureus was studied using a selection of laboratory-prepared and commercially available coated glass substrates using a simple methodology. Substrates were examined by scanning electron microscopy, atomic force microscopy and water droplet contact angles. It was found that microbial adhesion was independent of surface roughness, when this was of a lower magnitude than microbial size. It was also found that microbial adhesion was greater for hydrophilic surfaces than for hydrophobic ones, but that on a photoinduced superhydrophilic surface, microbes were more spread out—a potential benefit for more effective photocatalytic disinfection. It is suggested that hydrophobic and photoinduced superhydrophilic surface coatings both have potential as a means of reducing microbial fouling of surfaces. 相似文献
73.
Ahmad Ivan Karayan Adi Hersuni Dian Adisty Ardiyansyah Yatim 《Journal of Failure Analysis and Prevention》2011,11(5):481-486
A seawater inlet pipe failed in service. The visual examination showed that the backing bar was present inside the pipe and the failure was characterized by leaks at approximately 4–8 o’clock position near that backing bar. The finite element analysis of fluid in the seawater inlet pipe showed that the eddy zone was formed near the backing bar. The leaks and crater-like surfaces were noticed on the inner pipe surface at which the finite element analysis modeled the possibility of the formation of eddy zone. 相似文献
74.
Mary F. Wheeler Tim Wildey Ivan Yotov 《Computer Methods in Applied Mechanics and Engineering》2011,200(9-12):1251-1262
The aim of this paper is to introduce a new approach to efficiently solve sequences of problems that typically arise when modeling flow in stochastic porous media. The governing equations are based on Darcy’s law with a stochastic permeability field. Starting from a specified covariance relationship, the log permeability is decomposed using a truncated Karhunen–Loève expansion. Multiscale mortar mixed finite element approximations are used in the spatial domain and a nonintrusive sampling method is used in the stochastic dimensions. A multiscale mortar flux basis is computed for a single permeability, called a training permeability, that captures the main characteristics of the porous media, and is used as a preconditioner for each stochastic realization. We prove that the condition number of the preconditioned interface operator is independent of the subdomain mesh size and the mortar mesh size. Computational results confirm that our approach provides an efficient means to quantify the uncertainty for stochastic flow in porous media. 相似文献
75.
76.
Marina Vai Ivan Orlandi Paola Cavadini Lilia Alberghina Laura Popolo 《Yeast (Chichester, England)》1996,12(4):361-368
The GGP1/GAS1/CWH52 gene of Saccharomyces cerevisiae encodes a major exocellular 115 kDa glycoprotein (gp115) anchored to the plasma membrane through a glycosylphosphatidylinositol (GPI). The function of gp115 is still unknown but the analysis of null mutants suggests a possible role in the control of morphogenesis. PHR1 gene isolated from Candida alibicans is homologous to the GGP1 gene. In this report we have analysed the ability of PHR1 to complement a ggp1Δ mutation in S. cerevisiae. The expression of PHR1 controlled by its natural promoter or by the GGP1 promoter has been studied. In both cases we have observed a complete complementation of the mutant phenotype. Moreover, immunological analysis has revealed that PHR1 in budding yeast gives rise to a 75–80 kDa protein anchored to the membrane through a GPI, indicating that the signal for GPI attachment present in the C. albicans gene product is functional in S. cerevisiae. 相似文献
77.
Ivan Spasojevic Ines Batinic-Haberle Dubravka Barisin 《Propellants, Explosives, Pyrotechnics》1993,18(2):89-92
The igniter consisting of 34% Mg, 60% KNO3, 3% KClO4 and 3% organic binder was subjected to accelerated aging under the conditions of 85% relative humidity at 65°C, 75°C and 85°C, and at 75°C with 92% relative humidity. Chemical aging was followed through formation of Mg(OH)2 and KNO2. Functional characterization was accomplished in a device constructed to enable simultaneous determination of the heat of combustion and pressure-time recording of the combustion process of both fresh and aged samples. The maximum acceptable deterioration occured at different times depending upon the conditions. The acceleration factor for every 10°C at 85% relative humidity is on average 2.8, leading to a prediction of shelf life of not more than 4 years at 25°C. At the time when burning characteristics were significantly changed, the mixture suffered only slight chemical changes, with only about 1% Mg(OH)2 and 0.5% KNO2 being formed. Thus, no chemical changes should be tolerated in such formulations. 相似文献
78.
Stephen D. Fried Kosuke Fujishima Mikhail Makarov Ivan Cherepashuk Klara Hlouchova 《Journal of the Royal Society Interface》2022,19(187)
Recent developments in Origins of Life research have focused on substantiating the narrative of an abiotic emergence of nucleic acids from organic molecules of low molecular weight, a paradigm that typically sidelines the roles of peptides. Nevertheless, the simple synthesis of amino acids, the facile nature of their activation and condensation, their ability to recognize metals and cofactors and their remarkable capacity to self-assemble make peptides (and their analogues) favourable candidates for one of the earliest functional polymers. In this mini-review, we explore the ramifications of this hypothesis. Diverse lines of research in molecular biology, bioinformatics, geochemistry, biophysics and astrobiology provide clues about the progression and early evolution of proteins, and lend credence to the idea that early peptides served many central prebiotic roles before they were encodable by a polynucleotide template, in a putative ‘peptide-polynucleotide stage’. For example, early peptides and mini-proteins could have served as catalysts, compartments and structural hubs. In sum, we shed light on the role of early peptides and small proteins before and during the nucleotide world, in which nascent life fully grasped the potential of primordial proteins, and which has left an imprint on the idiosyncratic properties of extant proteins. 相似文献
79.
Olena V. Moshynets Taras P. Baranovskyi Olga S. Iungin Nadiia P. Kysil Larysa O. Metelytsia Ianina Pokholenko Viktoria V. Potochilova Geert Potters Kateryna L. Rudnieva Svitlana Y. Rymar Ivan V. Semenyuta Andrew J. Spiers Oksana P. Tarasyuk Sergiy P. Rogalsky 《International journal of molecular sciences》2022,23(2)
The choice of effective biocides used for routine hospital practice should consider the role of disinfectants in the maintenance and development of local resistome and how they might affect antibiotic resistance gene transfer within the hospital microbial population. Currently, there is little understanding of how different biocides contribute to eDNA release that may contribute to gene transfer and subsequent environmental retention. Here, we investigated how different biocides affect the release of eDNA from mature biofilms of two opportunistic model strains Pseudomonas aeruginosa ATCC 27853 (PA) and Staphylococcus aureus ATCC 25923 (SA) and contribute to the hospital resistome in the form of surface and water contaminants and dust particles. The effect of four groups of biocides, alcohols, hydrogen peroxide, quaternary ammonium compounds, and the polymeric biocide polyhexamethylene guanidine hydrochloride (PHMG-Cl), was evaluated using PA and SA biofilms. Most biocides, except for PHMG-Cl and 70% ethanol, caused substantial eDNA release, and PHMG-Cl was found to block biofilm development when used at concentrations of 0.5% and 0.1%. This might be associated with the formation of DNA–PHMG-Cl complexes as PHMG-Cl is predicted to bind to AT base pairs by molecular docking assays. PHMG-Cl was found to bind high-molecular DNA and plasmid DNA and continued to inactivate DNA on surfaces even after 4 weeks. PHMG-Cl also effectively inactivated biofilm-associated antibiotic resistance gene eDNA released by a pan-drug-resistant Klebsiella strain, which demonstrates the potential of a polymeric biocide as a new surface-active agent to combat the spread of antibiotic resistance in hospital settings. 相似文献
80.
Mark Portnoi Paul Anthony Haigh Thomas JM acdonald Filip Ambroz Ivan PParkin Izzat Darwazeh loannis Papakonstantinou 《光:科学与应用(英文版)》2021,10(1):29-40
Luminescent solar concentrators(LSCs)have recently emerged as a promising receiver technology in free-space optical communications due to their inherent ability to collect light from a wide field-of-view and concentrate it into small areas,thus leading to high optical gains.Several high-speed communication systems integrating LSCs in their detector blocks have already been demonstrated,with the majority of efforts so far being devoted to maximising the received optical power and the system's field-of-view.However,LSCs may pose a severe bottleneck on the bandwidth of such communication channels due to the comparably slow timescale of the fluorescence events involved,a situation further aggravated by the inherent reabsorption in these systems,and yet,an in-depth study into such dynamic effects remains absent in the field.To fill this gap,we have developed a comprehensive analytical solution that delineates the fundamental bandwidth limits of LSCs as optical detectors in arbitrary free-space optical links,and establishes their equivalence with simple RC low-pass electrical circuits.Furthermore,we demonstrate a time-domain Monte Carlo simulation platform,an indispensable tool in the multiparameter optimisation of LSC-based receiver systems.Our work offers vital insight into LSC system dynamic behaviour and paves the way to evaluate the technology for a wide range of applications,including visible light communications,high-speed video recording,and real-time biological imaging,to name a few. 相似文献