全文获取类型
收费全文 | 996篇 |
免费 | 70篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 265篇 |
金属工艺 | 16篇 |
机械仪表 | 16篇 |
建筑科学 | 16篇 |
矿业工程 | 2篇 |
能源动力 | 42篇 |
轻工业 | 205篇 |
水利工程 | 3篇 |
石油天然气 | 3篇 |
无线电 | 84篇 |
一般工业技术 | 157篇 |
冶金工业 | 82篇 |
原子能技术 | 5篇 |
自动化技术 | 161篇 |
出版年
2023年 | 9篇 |
2022年 | 36篇 |
2021年 | 34篇 |
2020年 | 25篇 |
2019年 | 37篇 |
2018年 | 33篇 |
2017年 | 36篇 |
2016年 | 40篇 |
2015年 | 36篇 |
2014年 | 36篇 |
2013年 | 72篇 |
2012年 | 59篇 |
2011年 | 76篇 |
2010年 | 50篇 |
2009年 | 59篇 |
2008年 | 60篇 |
2007年 | 33篇 |
2006年 | 48篇 |
2005年 | 38篇 |
2004年 | 37篇 |
2003年 | 28篇 |
2002年 | 23篇 |
2001年 | 18篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 24篇 |
1997年 | 16篇 |
1996年 | 13篇 |
1995年 | 11篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 8篇 |
1990年 | 3篇 |
1989年 | 9篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有1066条查询结果,搜索用时 171 毫秒
81.
Salvador?Jiménez-García Carlos?Santiago?López-Cajún Rosalba?Fuentes Victor?M.?Casta?oEmail author 《Materials Research Innovations》2003,7(4):199-204
Aluminium-based matrix composites were prepared by infiltration with an ammoniacal zirconium chelate within an Al matrix synthesized via Aluminium powder compactation. After infiltration, this chelate can be transformed in situ by sol-gel method that leads to tetragonal phases in zirconia, which in turn, transforms to monoclinic structure on heating. Based on Differential Thermal Analysis (DTA), Fourier Transformed Infrared (FTIR), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM), we confirm the reaction sequence to obtain the tetramer, the phase transformation sequence within the Al matrix, and the development of phases that leads to the synthesis of the Al-ZrO2 composite. 相似文献
82.
Naveen Shamsudhin Ye Tao Jordi Sort Bumjin Jang Christian L. Degen Bradley J. Nelson Salvador Pané 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(46):6363-6369
Ferromagnetic nanowires are finding use as untethered sensors and actuators for probing micro‐ and nanoscale biophysical phenomena, such as for localized sensing and application of forces and torques on biological samples, for tissue heating through magnetic hyperthermia, and for microrheology. Quantifying the magnetic properties of individual isolated nanowires is crucial for such applications. Dynamic cantilever magnetometry is used to measure the magnetic properties of individual sub‐500 nm diameter polycrystalline nanowires of Ni and Ni80Co20 fabricated by template‐assisted electrochemical deposition. The values are compared with bulk, ensemble measurements when the nanowires are still embedded within their growth matrix. It is found that single‐particle and ensemble measurements of nanowires yield significantly different results that reflect inter‐nanowire interactions and chemical modifications of the sample during the release process from the growth matrix. The results highlight the importance of performing single‐particle characterization for objects that will be used as individual magnetic nanoactuators or nanosensors in biomedical applications. 相似文献
83.
Salvador Alfaro Manuel Arruebo Joaquín Coronas Miguel Menndez Jesús Santamaría 《Microporous and mesoporous materials》2001,50(2-3):195-200
Zeolite MFI membranes were successfully prepared on both alumina and stainless steel tubular supports by crystallization of previously deposited silicate layers under a steam atmosphere. The resultant membranes were able to separate n/isobutane mixtures at relatively high temperatures, displaying separation selectivities of 11.3, 8.9 and 2.5 at 100, 230 and 330 °C, respectively. 相似文献
84.
Juan Ramn Gonzlez-Velasco Miguel Angel Gutirrez-Ortiz Arturo Romero Salvador 《加拿大化工杂志》1985,63(2):314-321
A method is proposed for solving the problem of temperature optimal control in tubular fixed-bed reactors with reaction systems described by Langmuir-Hinshelwood-Hougen-Watson kinetic equations. The optimization problem is formulated by N state differential equations corresponding to the N differential fixed-bed reactors in which the integral reactor is divided. It is solved using the control vector parameterization computational technique. The proposed method when applied to a simple reaction system reported previously in the literature gives analogous results, and thus validates the theory. This theory is applied to the dehydrogenation of benzyl alcohol to benzaldehyde. An analysis of optimality problem shows a strong influence of the temperature dependence of the ratio of reaction rate to deactivation reaction rate on the optimal policy. 相似文献
85.
Jaime González‐Buesa Ana Ferrer‐Mairal Rosa Oria María L. Salvador 《Packaging Technology and Science》2013,26(7):413-421
Most experimental systems for measuring the permeability of microperforated polymeric films are static, mainly because in dynamic systems the small differences in pressure on both sides of the perforation may result in serious errors in the measurements. The O2 and CO2 transmission rate through microperforations of different sizes (from 40 × 30 to 350 × 110 µm) were determined in a static and in a dynamic system. In the latter case, rather than the diffusive flow, the hydrodynamic flow generated by the difference in pressure was measured (between 5 and 90 mbar). This was determined by applying Bernouilli's theorem and an experimental equation potentially relating the area of the microperforation with the transmission rate. A comparison of the transmission rates obtained in both cases gives coefficients of determination close to one (>0.993). This means that measuring the hydrodynamic flow can be considered as an alternative for the quantification of the diffusive flow through a microperforation. This is a simple and quick methodology that does not require expensive equipment. Furthermore, this feature enables commercial leak detection equipment to be used to quantify diffusive transmission rates through microperforations. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
86.
Federico Pallottino Paolo Menesatti Corrado Costa Graziella Paglia Flavio R. De Salvador Daniele Lolletti 《Food and Bioprocess Technology》2010,3(1):155-159
According to FAO statistics, in 2000, Italy was the second largest hazelnut (Corylus avellana, L. 1753) producer in the world. The price of the stock depends on the nut quality (kernel/nut ratio, nut and seed defect,
percentage of peeling, and taste panel scores). The evaluation of peeling efficiency after toasting is generally conducted
by trained operators in sight on 100 kernels. This work tests two alternative objective methods of after toasting peeling
evaluation based on image analysis. Eleven hazelnut cultivars were analyzed and results were compared with the ones assessed
by trained operators. Images were analyzed with two statistical approaches: fixed values of RGB thresholding and trained K
Nearest Neighbors (KNN). Root mean squared error (RMSE), estimating the comparison between operators and the two image analysis-based
techniques, shows better results for KNN (6.6) with respect to fixed threshold (15.9). 相似文献
87.
Positron annihilation experiments have been performed on the metallic glasses Co58Ni10Fe5 B16Si11, Fe78B13Si9 and Fe81B13.5Si3.5C2 produced by melt-spinning. For the metallic glass Co58Ni10Fe5B16Si11 it has been found that the positron lifetime spectrum is either single-component or resolvable in two exponential terms, depending on the production parameters of the ribbons. The commercial metallic glass Fe78B13Si9 (2605S2) shows a two-component spectrum while the alloy Fe81 B13.5Si3.5C2 (2605SC) exhibits a single-component spectrum. After hydrogen charging no significant changes are observed in the positron lifetime of those metallic glasses which exhibit a single-component spectrum. For ribbons showing a two-term spectrum, the intensity of the long-lived componentl
2 decreases with the cumulative charging time. This decrease is interpreted in terms of hydrogen trapping in the structural defects responsible for the long-lived component. Differential scanning calorimetry of ribbons of Co58Ni10Fe5B16Si11 suggest that hydrogen in extended structural defects should induce some local structural change. 相似文献
88.
89.
H Silva S Jerez A Paredes J Salvo P Rentería A Ramírez C Montes 《Canadian Metallurgical Quarterly》1997,25(6):391-395
The debate about mercury and dental amalgam has been one of the longest running in dentistry, and shows no signs of abating. This study aimed to investigate perceptions about mercury in dental fillings among a representative sample of the Australian public. A random sub-sample of participants in a national dental telephone interview survey completed a follow-up postal questionnaire which included four items on dental mercury. The postal survey response rate was 85.2%. Concern about mercury in dental fillings was expressed by 37.5%, while 16.2% reported having requested fillings that do not contain mercury. Avoidance of dental care because of concern about mercury in fillings was reported by 5.8%, but only 4.7% reported having had fillings replaced because they contained mercury. The data indicate that there is a substantial degree of concern about mercury and dental amalgam among the Australian public, but that the dental behavioural and treatment-pattern consequences of that concern are infrequent. 相似文献
90.
Electrodeposition of Co-Ni and Co-Ni-Cu alloys was performed in a sulphate-citrate medium. Experimental electrodeposition parameters (pH, cobalt(II), nickel(II) and citrate concentrations) were varied in order to analyse their influence on the deposition. Anomalous Co-Ni codeposition occured in the citrate medium. High [Ni(II)]/[Co(II)] ratios (above 5) were suitable for the preparation of homogeneous magnetic Co-rich Co-Ni deposits of hexagonal close-packed (hcp) structure or face centred cubic (fcc) structure as a function of the deposition potential.The presence of very low copper(II) concentrations (<10−2 mol dm−3) in the nickel-cobalt bath makes it possible to incorporate copper in the deposits in amounts ranging from 5 to 60% Cu, although uniform deposits are obtained only for low copper percentages. These ternary deposits are solid solutions with fcc structure and magnetic behaviour both dependent on the deposition potential. 相似文献