全文获取类型
收费全文 | 340篇 |
免费 | 27篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 106篇 |
金属工艺 | 4篇 |
机械仪表 | 12篇 |
建筑科学 | 15篇 |
能源动力 | 12篇 |
轻工业 | 82篇 |
水利工程 | 10篇 |
石油天然气 | 3篇 |
无线电 | 13篇 |
一般工业技术 | 54篇 |
冶金工业 | 23篇 |
原子能技术 | 2篇 |
自动化技术 | 27篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 10篇 |
2021年 | 21篇 |
2020年 | 17篇 |
2019年 | 8篇 |
2018年 | 14篇 |
2017年 | 17篇 |
2016年 | 9篇 |
2015年 | 12篇 |
2014年 | 19篇 |
2013年 | 22篇 |
2012年 | 30篇 |
2011年 | 24篇 |
2010年 | 14篇 |
2009年 | 23篇 |
2008年 | 17篇 |
2007年 | 14篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 7篇 |
2002年 | 10篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1985年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有368条查询结果,搜索用时 15 毫秒
81.
Maria João Cardoso Anca Ioana Nicolau Daniela Borda Line Nielsen Rui Leandro Maia Trond Møretrø Vânia Ferreira Susanne Knøchel Solveig Langsrud Paula Teixeira 《Comprehensive Reviews in Food Science and Food Safety》2021,20(3):2716-2741
Nontyphoidal salmonellae are among the most prevalent foodborne pathogens causing gastrointestinal infections worldwide. A high number of cases and outbreaks of salmonellosis are associated with the consumption of eggs and egg products, and several of these occur at the household level. The aim of the current study is to critically evaluate the current status of knowledge on Salmonella in eggs from a consumer's perspective, analyzing the hazard occurrence and the good practices that should be applied to reduce salmonellosis risk. Following a HACCP (Hazard Analysis and Critical Control Point) based approach, some steps along the food journey were identified as Critical Consumer Handling (CCH)—steps in which consumers, through their behavior or choice, can significantly reduce the level of Salmonella in eggs and egg products. From shopping/collecting to consumption, each of these steps is discussed in this review to provide an evidence-based overview of risk factors of human salmonellosis related to egg consumption. The main message to consumers is to choose Salmonella-free eggs (those that some official entity or producer guarantees that does not contain Salmonella), when available, especially for dishes that are not fully heat treated. Second, as guaranteed Salmonella-free eggs are only available in a few countries, refrigerated storage from the point of collection and proper cooking will significantly reduce the risk of salmonellosis. This will require a revision of the actual recommendations/regulations, as not all ensure that eggs are maintained at temperatures that prevent growth of Salmonella from collection until the time of purchasing. 相似文献
82.
This paper addresses reliable and efficient calculation of the mode of a multivariate sample, which is a classical fusion function. In particular, we focus on the inputs given on the unit simplex, when aggregating elements of Atanassov intuitionistic fuzzy sets, interval-valued fuzzy sets and their extensions, as well as compositional data. We outline the use of a specially designed 2-additive fuzzy measures and the Choquet integral for the purposes of reducing computational complexity in higher dimensions. We present computational analysis and benchmark four different methods of density-based mode estimation. 相似文献
83.
Male-partner abuse, although it is prevalent among medical patients in emergency rooms, primary care, and obstetric clinics, is infrequently screened for and therefore inadequately treated by the majority of physicians. Research studies to support these conclusions are reviewed. On the basis of information presented, it is recommended that psychotherapists (1) recognize that absence of partner-violence injury in medical records often reveals lack of proper diagnosis rather than lack of evidence; (2) coach their patients on the selection of an appropriate provider and in approaches to disclose their history in a safe manner; and (3) advocate for better medical education regarding male-partner violence. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
84.
JINR Gomes GMB Soares R. Hrdina AMF Oliveira-Campos JCVP Moura HLS Maia 《Coloration Technology》1996,112(1):19-22
The synthesis of a reactive dye in the anhydride form is described, and its kinetics of hydrolysis investigated at various pH values. Two different hydrolysis products were identified. The experimental rate constants were determined by nonlinear approximation. It was found that the experimental rate constant depends on pH, with the maximum between pH 5 and 6. The best wool dyeing conditions were obtained by dyeing for 60 min at 100d?C and pH 7. 相似文献
85.
Laise Maia Lopes Mariana Agostini de Moraes Marisa Masumi Beppu 《Journal of Polymer Research》2018,25(9):198
Silk fibroin (SF) and sodium alginate (SA) are natural polymers with many applications as biomaterials. It is possible to make blends with them in order to improve their properties. Those blends are partially miscible; therefore, understanding the mechanism and phase equilibrium of this system is important to better understand the interaction between these natural polymers. This work analyzed the mechanism of phase separation of SF and SA blends with different composition in solution and in the solid state (as membranes) using small angle light scattering with a He-Ne laser. Polymer interaction and conformation were investigated by Fourier-Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR) and X-Ray Diffraction (XRD), and membrane morphology was analyzed by Scanning Electron Microscopy (SEM). SEM images showed interpenetrated globules in the matrix. Light scattering profile for blends in solution and in the solid state showed a peak of intensity suggesting that phase separation occurs by spinodal decomposition. 相似文献
86.
Rodolpho M. de Andrade Jefferson S. de Gois Isabela Maia Toaldo Diego Barros Batista Aderval S. Luna Daniel L. G. Borges 《Food Analytical Methods》2017,10(5):1209-1215
This work presents a direct and straightforward approach for the determination of trace elements in fish muscle, oyster, and bovine liver via direct solid sample analysis (SS) using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The preliminary studies revealed the presence of spectral interferences at the analytical line of Ni at 231.096 nm, which could be corrected subtracting the spectrum of SiO and PO from the sample spectra using least-squares background correction. Moreover, all meat samples were proven homogeneous according to the homogeneity factor (H e) (all values were <10 mg½). Pyrolysis (Tp) and atomization (Ta) temperatures were studied and optimized as 800 °C (Tp) and 2500 °C (Ta) for Mn, 700 °C (Tp) and 2600 °C (Ta) for Ni, and 600 °C (Tp) and 2500 °C (Ta) for Rb. Calibration against aqueous standards was proven feasible for Mn determination, whereas Ni and Rb required calibration against solid standards for their quantification. The detection limits achieved were demonstrated adequate for application to food analysis (0.005 μg g?1 for Mn, 0.002 μg g?1 for Ni, and 0.1 μg g?1 for Rb). The developed method was successfully applied for the elemental analysis of fish muscle, oyster, and bovine liver and three certified reference materials, demonstrating good agreement with the certified values and with the reference technique at a 95 % statistical confidence level. 相似文献
87.
Maia MA Fairhurst MC 《IEEE transactions on pattern analysis and machine intelligence》1983,(6):661-664
The existence of an upper bound for the error probability as a function of I-divergences between an original and an approximating distribution is proved. Such a bound is shown to be a monotonic nondecreasing function of the I-divergences, reaching the Bayes error probability when they vanish. It has been shown that if the closeness between the original and approximating distributions is assessed by the probability of error associated with a particular two-class recognition problem in which those functions are the class conditional distributions, then the best upper bound for such probability is ? regardless of the value of the I-divergences between them. Approaching the approximation problem from a rather different viewpoint, this correspondence considers the problem of a two-class discrete measurement classification where the original distributions are replaced by approximations, and its effects on the probability of error. The corresponding analysis is presented in detail. 相似文献
88.
The influence of burner-port geometry in the mechanisms of hydrocarbon oxidation and NOx formation from a 50 kW industrial-type methane-fired burner was investigated experimentally. Imaging and tomographic reconstruction techniques were used to assess the effects of port geometry upon flame visible length and C2 chemiluminescence distribution in the recirculation zone. C2 emission of methane flames depicts that low fuel jet velocities allow very rich conditions at recirculation zone and lead methane oxidation through O2-scarcity mechanism. Higher velocities imply that methane oxidises via a path including dissociation into free radicals. In-furnace measurements were performed from a refractory-lined vertical furnace. NOx concentration results revealed that NO formation is closely connected with the dissociation process, suggesting that prompt-NOx mechanism is more important than hitherto supposed. 相似文献
89.
Susana Filipe João Manuel Maia Catarina Rosa Leal Maria Teresa Cidade 《应用聚合物科学杂志》2007,105(3):1521-1532
The main aim of this work is to study the influence of the application of different processing conditions on the morphological and mechanical properties of thermoplastic/LCP blends, in which the viscosity ratios are inferior to unity and decrease with increasing temperature. The way the microstructure evolves along the extruder determines the final morphology and thus, the mechanical performance of the systems. In the present case, the mechanical properties are related with the degree of fibrillation in the final composites. The best degree of fibrillation was obtained for low screw speeds and temperatures and for intermediate outputs. The use of high screw speeds and processing temperatures results in a decrease of the viscosity ratio, in the former case via an increase in the viscous dissipation, at the regions of higher shear rates (kneading‐elements). The application of a lower processing temperature is advantageous for deformation, break‐up, and fibrillar formation because of the higher viscosity ratios and higher shear stresses involved. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
90.
This article reports a study on the preparation, densification process, and structural and optical properties of SiO2-Ta2O5 nanocomposite films obtained by the sol-gel process. The films were doped with Er3+, and the Si:Ta molar ratio was 90:10. Values of refractive index, thickness and vibrational modes in terms of the number of layers and thermal annealing time are described for the films. The densification process is accompanied by OH group elimination, increase in the refractive index, and changes in film thickness. Full densification of the film is acquired after 90 min of annealing at 900 °C. The onset of crystallization and devitrification, with the growth of Ta2O5 nanocrystals occurs with film densification, evidenced by high-resolution transmission electron microscopy. The Er3+-doped nanocomposite annealed at 900 °C consists of Ta2O5 nanoparticles, with sizes around 2 nm, dispersed in the SiO2 amorphous phase. The main emission peak of the film is detected at around 1532 nm, which can be assigned to the 4I13/2 → 4I15/2 transition of the Er3+ ions present in the nanocomposites. This band has a full width at half medium of 64 nm, and the lifetime measured for the 4I13/2 levels is 5.4 ms, which is broader compared to those of other silicate systems. In conclusion, the films obtained in this work are excellent candidates for use as active planar waveguide. 相似文献