全文获取类型
收费全文 | 2826篇 |
免费 | 165篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 119篇 |
综合类 | 31篇 |
化学工业 | 583篇 |
金属工艺 | 82篇 |
机械仪表 | 71篇 |
建筑科学 | 88篇 |
矿业工程 | 20篇 |
能源动力 | 111篇 |
轻工业 | 414篇 |
水利工程 | 30篇 |
石油天然气 | 21篇 |
武器工业 | 1篇 |
无线电 | 202篇 |
一般工业技术 | 504篇 |
冶金工业 | 175篇 |
原子能技术 | 53篇 |
自动化技术 | 498篇 |
出版年
2023年 | 20篇 |
2022年 | 33篇 |
2021年 | 66篇 |
2020年 | 58篇 |
2019年 | 57篇 |
2018年 | 100篇 |
2017年 | 96篇 |
2016年 | 88篇 |
2015年 | 81篇 |
2014年 | 133篇 |
2013年 | 243篇 |
2012年 | 218篇 |
2011年 | 283篇 |
2010年 | 158篇 |
2009年 | 163篇 |
2008年 | 96篇 |
2007年 | 106篇 |
2006年 | 60篇 |
2005年 | 123篇 |
2004年 | 64篇 |
2003年 | 69篇 |
2002年 | 93篇 |
2001年 | 66篇 |
2000年 | 31篇 |
1999年 | 32篇 |
1998年 | 60篇 |
1997年 | 53篇 |
1996年 | 35篇 |
1995年 | 25篇 |
1994年 | 23篇 |
1993年 | 17篇 |
1992年 | 14篇 |
1991年 | 13篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 19篇 |
1983年 | 10篇 |
1982年 | 6篇 |
1981年 | 9篇 |
1980年 | 11篇 |
1979年 | 15篇 |
1978年 | 12篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1974年 | 8篇 |
1973年 | 11篇 |
排序方式: 共有3003条查询结果,搜索用时 156 毫秒
81.
A model-based approach to reconstruction of 3D human arm motion from a monocular image sequence taken under orthographic
projection is presented. The reconstruction is divided into two stages. First, a 2D shape model is used to track the arm silhouettes
and second-order curves are used to model the arm based on an iteratively reweighted least square method. As a result, 2D
stick figures are extracted. In the second stage, the stick figures are backprojected into the scene. 3D postures are reconstructed
using the constraints of a 3D kinematic model of the human arm. The motion of the arm is then derived as a transition between
the arm postures. Applications of these results are foreseen in the analysis of human motion patterns.
Received: 26 January 1996 / Accepted: 17 July 1997 相似文献
82.
P. Roca i Cabarrocas S. Kasouit B. Kalache R. Vanderhaghen Y. Bonnassieux M. Elyaakoubi I. French 《Journal of the Society for Information Display》2004,12(1):3-9
Abstract— Top‐gate and bottom‐gate microcrystalline‐silicon thin‐film transistors (TFTs) have been produced at low temperature (150–250°C) by the standard radio‐frequency glow‐discharge technique using three preparation methods: the hydrogen dilution of silane in hydrogen, the layer‐by‐layer technique, and the use of SiF4‐Ar‐H2 feedstock. In all cases, a stable top‐gate TFT with mobility values around 1 cm2/V‐sec have been achieved, making them suitable for basic circuit on glass applications. Moreover, the use of SiF4 gas combined with specific plasma treatments of the a‐SiN:H dielectric produces large columns, even at the interface with the dielectric. This leads to stable bottom‐gate TFTs, fully compatible with today's a‐Si:H production facilities, reaching mobility values up to 3 cm2/V‐sec. These devices are an interesting alternative to laser‐crystallized polysilicon thin films in a growing number of applications. 相似文献
83.
The aim of this work was to show that with the use of the surface roughness parameters Ssk and Sku we can predict tribological behavior of contact surfaces and use these parameters to plan surface texturing. This article presents a continuation of our research on virtual texturing and experimental work on surface textures in the form of channels. For this investigation, steel samples were laser surface textured in the shape of dimples with different spacings between the dimples and different dimple depths. The experimental results confirmed that the parameters Ssk and Sku can be used to design the surface texturing, where a higher value of Sku and more negative Ssk lead to lower friction. 相似文献
84.
Linas Minkevičius Vincas Tamošiūnas Martynas Kojelis Ernestas Žąsinas Virginijus Bukauskas Arūnas Šetkus Renata Butkutė Irmantas Kašalynas Gintaras Valušis 《Journal of Infrared, Millimeter and Terahertz Waves》2017,38(6):689-707
A detailed electrical characterization of high-performance bow-tie InGaAs-based terahertz detectors is presented along with simulation results. The local surface potential and tunnelling current were scanned over the surfaces of the detectors by means of Kelvin probe force microscopy (KPFM) and scanning tunnelling microscopy (STM), which also enabled the determination of the Fermi level. Current-voltage curves were measured and modelled using the Synopsys Sentaurus TCAD package to gain deeper insight into the processes involved in detector operation. In addition, we performed finite-difference time-domain (FDTD) simulations to reveal features related to changes in the electric field due to the metal detector contacts. The investigation revealed that field-effect-induced conductivity modulation is a possible mechanism contributing to the high sensitivity of the studied detectors. 相似文献
85.
We studied the morphological properties of precipitated, nanostructured, boehmite coatings on a polished alumina surface by exploiting the aluminum nitride (AlN) powder hydrolysis at elevated temperatures. The hydrolysis tests of the 3 wt% AlN powder suspensions in the temperature range 50–90 °C were performed in order to estimate the time needed for the synthesis of the coatings. They consisted of interlocked boehmite lamellas, positioned perpendicularly to the ceramic surface, and they exhibited a strong temperature-dependent size and surface density. The aim of this research was a quantitative assessment of the as-formed boehmite coatings. Based on electron microscopy micrographs, a stereometric analysis of the as-prepared coatings was performed in order to estimate the relevant geometric parameters of the lamellas. In spite of the temperature-dependent lamellas’ size and surface density, the specific volume of the coatings was similar for all the synthesis temperatures. 相似文献
86.
Elizabeth Elacqua Tomislav Friščić Leonard R. MacGillivray 《Israel journal of chemistry》2012,52(1-2):53-59
In this account, we review the synthesis of [2.2]paracyclophanes in the organic solid state. Reactions in crystalline solids provide a means to obtain molecules with high degrees of stereocontrol that can also be unattainable in solution. We show that [2.2]paracyclophanes form in the solid state stereospecifically and in quantitative yield via intermolecular [2+2] double photodimerization reactions. The double cycloaddition that affords a paracyclophane in the solid state does not readily occur in solution. Small molecules in the form of hydrogen-bond-donor templates can provide access to [2.2]paracyclophanes in a solid by design. A [2.2]paracyclophane obtained using a hydrogen-bond template is shown to exhibit attractive optical properties and has been employed as a building block of a metal-organic framework (MOF). 相似文献
87.
Capillary zone electrophoresis (CZE) has been applied to separation and characterisation of enzymatic (tryptic) hydrolysates of water-soluble proteins from Bacillus thuringiensis (Bt)-transgenic (Aristis-Bt) and two native non-transgenic (Aristis and Coventry) maize varieties. Water-soluble proteins were extracted from the flour of these maize species and digested by bovine pancreatic trypsin immobilised on agarose gel in 100 mM ammonium hydrocarbonate buffer, pH 7.9. The yielded tryptic digests of proteins were analysed by CZE in four acidic background electrolytes (BGEs) (100 mM H3PO4, 50 mM Tris, pH 2.25; 500 mM acetic acid, pH 2.54; 200 mM formic acid, 200 mM acetic acid, pH 2.05; and 200 mM iminodiacetic acid, pH 2.26) using a lab-made CZE apparatus equipped with bare fused silica capillary and UV-absorption detector operating at 206 nm. Among the tested BGEs, the best resolution of the tryptic peptides of extracted proteins of the above three maize species was obtained in isoelectric BGE, 200 mM iminodiacetic acid, pH 2.26. Selected resolved tryptic peptides of proteins were characterised by effective electrophoretic mobilities and corrected (migration times normalised) peak areas. Some significant relative qualitative and quantitative differences in CZE-UV profiling of tryptic protein digests were found, which can be potentially used to differentiate transgenic Aristis Bt and non-transgenic Aristis varieties or two native non-transgenic varieties, Aristis and Coventry. 相似文献
88.
89.
Juš Kocijan Gregor Žunič Stanko Strmčnik Damir Vrančić 《International journal of control》2013,86(14):1082-1091
In the paper an approach to the non-linear control of a gas-liquid separation plant is presented. To solve the problem the fuzzy gain-scheduling method was used and implemented on a programmable logic controller (PLC). Velocity-based linearization approach was used for control system design and implementation for the first time in process control application. Emphasis was placed on the appropriate adaptation of the method and some important implementation issues. The algorithm was carefully designed and tested by using ordinary simulation, hardware-in-the-loop simulation, and experiments on the real plant. The results show that the proposed approach substantially improves the closed-loop performance of the plant. 相似文献
90.
Sonja Peci? M. Veljovi? S. Despotovi? I. Lesko?ek-?ukalovi? M. Jadranin V. Te?evi? M. Nik?i? N. Niki?evi? 《European Food Research and Technology》2012,235(3):479-487
?ljivovica and Prepe?enica are traditional Serbian distillated beverages made from varieties of plum, of the genus Prunus. The ageing in wooden casks not only improves the sensory characteristics, but also changes the content of total polyphenols and contributes to the other important health properties, such as the increase of their antioxidant capacity. In this study, home-made brandy (?ljivovica and Prepe?enica) samples were used, which matured in casks during the time period from 10 to 47?years. The aim of this investigation was to examine the influence of the ageing parameters (time period and type of wooden casks) and raw material (plum cultivars) on the total polyphenol content, amount of certain phenol compounds, sensory properties, colour and antioxidant properties in matured brandies. The individual phenol components were determinated using HPLC system equipped with diode array detector, while the total phenol content and antioxidant activity was estimated using spectrophotometric methods (Folin?CCiocalteu, DPPH, FRAP and TEAC). Total polyphenol content (TPC) of aged Prepe?enica samples was ranged from 230.26 to 890.26?mg/L gallic acid equivalents (GAE mg/L), whereas the TPC of ?ljivovica sample was 110.38?mg/L. Antioxidant capacity of analysed Prepe?enica samples and ?ljivovica sample was in strong correlation with TPC. Total sensory score of all samples was very high and varied between 18.2 and 19.8. The obtained results have shown that the benefit of longer maturation on sensory characteristics is well recognized, but the improvement has some limitation. 相似文献