全文获取类型
收费全文 | 297篇 |
免费 | 5篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 35篇 |
金属工艺 | 4篇 |
机械仪表 | 7篇 |
建筑科学 | 26篇 |
能源动力 | 13篇 |
轻工业 | 34篇 |
水利工程 | 1篇 |
无线电 | 31篇 |
一般工业技术 | 25篇 |
冶金工业 | 12篇 |
自动化技术 | 113篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 8篇 |
2014年 | 8篇 |
2013年 | 21篇 |
2012年 | 12篇 |
2011年 | 27篇 |
2010年 | 8篇 |
2009年 | 20篇 |
2008年 | 14篇 |
2007年 | 20篇 |
2006年 | 16篇 |
2005年 | 11篇 |
2004年 | 10篇 |
2003年 | 7篇 |
2002年 | 12篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1976年 | 1篇 |
1960年 | 2篇 |
1926年 | 2篇 |
1924年 | 3篇 |
排序方式: 共有302条查询结果,搜索用时 15 毫秒
71.
Matteo Trimarchi Dorina Lauritano Gianpaolo Ronconi Alessandro Caraffa Carla E. Gallenga Ilias Frydas Spyros K. Kritas Vittorio Calvisi Pio Conti 《International journal of molecular sciences》2022,23(21)
Much evidence suggests autoimmunity in the etiopathogenesis of periodontal disease. In fact, in periodontitis, there is antibody production against collagen, DNA, and IgG, as well as increased IgA expression, T cell dysfunction, high expression of class II MHC molecules on the surface of gingival epithelial cells in inflamed tissues, activation of NK cells, and the generation of antibodies against the azurophil granules of polymorphonuclear leukocytes. In general, direct activation of autoreactive immune cells and production of TNF can activate neutrophils to release pro-inflammatory enzymes with tissue damage in the gingiva. Gingival inflammation and, in the most serious cases, periodontitis, are mainly due to the dysbiosis of the commensal oral microbiota that triggers the immune system. This inflammatory pathological state can affect the periodontal ligament, bone, and the entire gingival tissue. Oral tolerance can be abrogated by some cytokines produced by epithelial cells and activated immune cells, including mast cells (MCs). Periodontal cells and inflammatory–immune cells, including mast cells (MCs), produce cytokines and chemokines, mediating local inflammation of the gingival, along with destruction of the periodontal ligament and alveolar bone. Immune-cell activation and recruitment can be induced by inflammatory cytokines, such as IL-1, TNF, IL-33, and bacterial products, including lipopolysaccharide (LPS). IL-1 and IL-33 are pleiotropic cytokines from members of the IL-1 family, which mediate inflammation of MCs and contribute to many key features of periodontitis and other inflammatory disorders. IL-33 activates several immune cells, including lymphocytes, Th2 cells, and MCs in both innate and acquired immunological diseases. The classic therapies for periodontitis include non-surgical periodontal treatment, surgery, antibiotics, anti-inflammatory drugs, and surgery, which have been only partially effective. Recently, a natural cytokine, IL-37, a member of the IL-1 family and a suppressor of IL-1b, has received considerable attention for the treatment of inflammatory diseases. In this article, we report that IL-37 may be an important and effective therapeutic cytokine that may inhibit periodontal inflammation. The purpose of this paper is to study the relationship between MCs, IL-1, IL-33, and IL-37 inhibition in acute and chronic inflamed gingival tissue. 相似文献
72.
The aliphatic and polycyclic aromatic fractions of dust collected in the vicinity of recycled paper processing operations were analyzed using gas chromatography/mass spectrometry. Total measured dust concentration (up to 8.73+/-2.02 mg/m3) fluctuated substantially in the different steps of paper manufacture. This was attributed to the type of the operation such as, the release of fibers and particles during paper cutting and the use of reactive chemicals and excessive water under high temperature and pressure during the bleaching and the water rinsing/drying step. Particulate polycyclic aromatic hydrocarbons (PAHs) (from fluorene to benzo[ghi]perylene with mean concentrations from 3.8+/-0.5 to 41.4+/-0.4 ng/m3) and the unresolved mixture of branched, cyclic and unsaturated hydrocarbons (UCM) were measured in all samples while, n-alkanes from n-C20 to n-C27, were only observed in cutting and packaging areas (from 180.6+/-18.9 to 4297.9+/-794.9 ng/m3). The profile of occupational PAHs in bleaching and treatment of contaminated recycled raw paper was comparable to that observed for anthropogenic activities. The values of molecular diagnostic ratios indicated the contribution of oil residues and emissions from worklifts and other equipment used for pulp and paper handling. Total benzo[a]pyrene-equivalent (BaP) concentrations of particulate PAHs (varied from 323 up to 1104 pg/m3), provided evidence that workers were exposed to high quantities of PAHs as compared with exposures to urban air and other indoor settings, posing long-term threat to their health. 相似文献
73.
74.
Modeling of continuous self‐classifying spiral jet mills part 1: Model structure and validation using mill experiments 下载免费PDF全文
Derek Starkey Cathy Taylor Nathan Morgan Katie Winston Spyros Svoronos John Mecholsky Kevin Powers Ron Iacocca 《American Institute of Chemical Engineers》2014,60(12):4086-4095
The objective of this work is to develop a milling model for a continuous self‐classifying spiral air jet mill. Its foundation is a population balance model with selection and breakage distribution functions that have been related to a minimal number of mill‐dependent and powder‐dependent parameters. Initially, experimentation is required to determine the mill‐dependent parameters for a specific mill, by milling a “base” powder at multiple operating conditions. Powder‐dependent parameters can be determined from either mill experiments or from material characterization measurements that require small amounts of powder (presented in Part 2). Ultimately, the milling model presented successfully predicts the product particle size using as inputs the feed particle‐size distribution and mill operating conditions. Three crystalline powders, sodium bicarbonate, lactose monohydrate, and sucrose, have been used to test the proposed milling model. © 2014 American Institute of Chemical Engineers AIChE J 60: 4086–4095, 2014 相似文献
75.
Hildebrandt L Henry KM Kroll JH Worsnop DR Pandis SN Donahue NM 《Environmental science & technology》2011,45(15):6329-6335
According to the pseudo-ideal mixing assumption employed in practically all chemical transport models, organic aerosol components from different sources interact with each other in a single solution, independent of their composition. This critical assumption greatly affects modeled organic aerosol concentrations, but there is little direct experimental evidence to support it. A main experimental challenge is that organic aerosol components from different sources often look similar when analyzed with an aerosol mass spectrometer. We developed a new experimental method to overcome this challenge, using isotopically labeled compounds ((13)C or D) and a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). We generated mixtures of secondary organic aerosol (SOA) from isotopically labeled toluene and from unlabeled α-pinene and used the HR-ToF-AMS data to separate these different SOA types. We evaluated their interaction by comparing the aerosol mass yields of toluene and α-pinene when the SOA was formed in these mixtures to their yields when the SOA was formed in isolation. At equilibrium, our results are consistent with pseudo-ideal mixing of anthropogenic and biogenic SOA components from these chemically dissimilar precursors. 相似文献
76.
Mylène Struijk Spyros Angelopoulos Carol X. J. Ou Robert M. Davison 《Information Systems Journal》2023,33(4):912-952
The use of digital technologies for extracting information from various data sources can help organisations to reduce uncertainty and improve decision-making. The increasing availability in volume, velocity, and variety of data, however, can give rise to significant risks and challenges in ensuring a high level of information quality (IQ). Pre-digital organisations can be particularly susceptive to such challenges due to their limited experience with digital technologies and IQ governance. We adopt a theory-infused interventionist research approach to assist a pre-digital multinational military organisation in navigating its digital transformation (DT) by focusing on IQ. We design and implement an IQ strategy (IQS) by drawing upon organisational information processing theory and examining how the level of IQ can affect the balance between information processing requirements and capacity. We demonstrate that an IQS that incorporates both technological, as well as IQ governance solutions, can support organisations in setting the scope of their DT, decreasing employees' resistance to change, and increasing their satisfaction, while concurrently improving organisational efficiency. Our work stresses the importance of IQ in the digital era and delineates how pre-digital organisations can navigate DT by strategically addressing IQ. 相似文献
77.
Chrysovalantou Ziogou Spyros Voutetakis Michael C. Georgiadis 《Computers & Chemical Engineering》2011,35(9):1886-1900
The aim of this work is the development and experimental validation of a detailed dynamic fuel cell model using the gPROMS modeling environment. The model is oriented towards optimization and control and it relies on material and energy balances as well as electrochemical equations including semi-empirical equations. For the experimental validation of the model a fully automated and integrated hydrogen fuel cell testing unit was used. The predictive power of the model has been compared with the data obtained during load change experiments. A sensitivity analysis has been employed to reveal the most critical empirical model parameters that should be estimated using a systematic estimation procedure. Model predictions are in good agreement with experimental data under a wide range of operating conditions. 相似文献
78.
79.
Air quality monitoring using airborne platforms is rapidly gaining ground as unmanned aerial vehicles (UAVs) are becoming easier, less expensive, and safer to operate on a routine basis. To facilitate measurements of key atmospheric properties, however, efforts are still required in developing/testing miniaturized instruments for use onboard UAVs. Here, we test two commercially available cost-effective/lightweight optical particle counters (OPCs; Alphasense Model N2) capable of measuring the size distributions of airborne particles having diameters from 380 nm to 17 μm. Tests were made against a reference and recently calibrated OPC (Grimm Model 1.109) using monodisperse polystyrene spheres. All instruments were placed in a chamber in which the temperature and pressure varied in the ranges of ?5 to 23°C and 0.7 to 1.0 atm, respectively; conditions typically encountered during UAV flights. Agreement in the particle number concentrations measured by the Alphasense and the Grimm OPCs was within 40%, under all experimental conditions used in this work, when particles having sizes >1 μm were employed during the tests. Deviations higher than 50%, however, were observed when the instruments were tested with 1.0- and 0.8-μm polysterene spheres. The particle sizes reported by both Alphasense OPCs were within ± 5% with respect to the nominal polysterene spheres’ size under all operating pressures and temperatures down to 5°C. At lower temperatures, the sizing accuracy of one of the two Alphasense OPCs degraded significantly. While our findings support that the Alphasense OPCs can be used at low temperature/pressure conditions, they should be carefully tested prior the measurements to ensure good performance.Copyright © 2018 The Authors 相似文献
80.
In the design of long haul radio relay links using frequencies above 10 GHz, it is necessary to estimate outage time occurrence probability due to rain attenuation for multirelay systems. A theoretical predictive method is proposed in this paper which is involved with the analysis of joint attenuation exceedance probabilities using a very simple exponentially shaped spatial rainrate profile. This same rain structure model has been originally developed for the prediction of rain attenuation of microwave satellite links. Numerical results have been obtained and compared with experimental data taken from a multirelay system located in Japan. 相似文献