全文获取类型
收费全文 | 10928篇 |
免费 | 946篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 85篇 |
综合类 | 8篇 |
化学工业 | 2739篇 |
金属工艺 | 123篇 |
机械仪表 | 333篇 |
建筑科学 | 505篇 |
矿业工程 | 23篇 |
能源动力 | 230篇 |
轻工业 | 2249篇 |
水利工程 | 103篇 |
石油天然气 | 21篇 |
无线电 | 822篇 |
一般工业技术 | 2079篇 |
冶金工业 | 506篇 |
原子能技术 | 25篇 |
自动化技术 | 2036篇 |
出版年
2024年 | 37篇 |
2023年 | 152篇 |
2022年 | 140篇 |
2021年 | 372篇 |
2020年 | 304篇 |
2019年 | 305篇 |
2018年 | 477篇 |
2017年 | 479篇 |
2016年 | 569篇 |
2015年 | 446篇 |
2014年 | 571篇 |
2013年 | 1052篇 |
2012年 | 1013篇 |
2011年 | 910篇 |
2010年 | 575篇 |
2009年 | 538篇 |
2008年 | 602篇 |
2007年 | 548篇 |
2006年 | 431篇 |
2005年 | 313篇 |
2004年 | 298篇 |
2003年 | 248篇 |
2002年 | 237篇 |
2001年 | 136篇 |
2000年 | 134篇 |
1999年 | 90篇 |
1998年 | 82篇 |
1997年 | 85篇 |
1996年 | 71篇 |
1995年 | 65篇 |
1994年 | 67篇 |
1993年 | 55篇 |
1992年 | 39篇 |
1991年 | 30篇 |
1990年 | 22篇 |
1989年 | 24篇 |
1988年 | 24篇 |
1987年 | 13篇 |
1986年 | 19篇 |
1985年 | 29篇 |
1984年 | 28篇 |
1983年 | 18篇 |
1982年 | 21篇 |
1981年 | 24篇 |
1980年 | 16篇 |
1979年 | 26篇 |
1978年 | 13篇 |
1974年 | 9篇 |
1973年 | 11篇 |
1947年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Quintanar-Reséndiz Ana L. Rodríguez-Santos Francisco Pichardo-Méndez Josué L. Delgado-Gutiérrez Guillermo Ramírez Omar Jiménez Vázquez-Medina Rubén 《Multimedia Tools and Applications》2021,80(13):19513-19538
Multimedia Tools and Applications - It is proposed a forensic method for the capture device identification from digital images, which requires two elements: i) a digital image subject to... 相似文献
82.
Urrea Claudio Pascal José 《International Journal of Control, Automation and Systems》2021,19(8):2902-2909
International Journal of Control, Automation and Systems - This article presents the design of a parameter identification model for industrial manipulator robots. This model includes the dynamics... 相似文献
83.
Universal Access in the Information Society - Measurement of both usability and accessibility is an important concern in software development today. However, while a great amount of attention has... 相似文献
84.
Marine Harguindeguy Claire Antonelli Marie-Pierre Belleville José Sanchez-Marcano Céline Pochat-Bohatier 《应用聚合物科学杂志》2021,138(2):49669
Millimeter-size beads of gelatin are manufactured by dripping process to give enzyme supports qualified for micropollutants biodegradation in alternative wastewater treatment. The bead diameter is dependent on the tip diameter, the gelatin solution viscosity and the swelling of polymer chains in the collecting bath. Chemical crosslinking was performed with glutaraldehyde using optimal concentration to give mechanical and thermal properties suitable for application in stirred reactor in aqueous medium. Laccases from Trametes versicolor are grafted on the gelatin beads with glutaraldehyde. Sixty percentage of the initial enzymatic activity, evaluated by the oxidation of 2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS) is maintained after 10 successive cycles of reaction. Thermal stability at 60°C of immobilized biocatalysts is improved when compared to free enzymes (45% vs 10% of relative activity after 6 h of incubation). The simplicity of the procedure to form gelatin beads and their properties make them promising bio-based and biodegradable support for enzyme immobilization. 相似文献
85.
Luciana Gampert Miranda Carolina Pereira Peglow Victória Cardoso Deorristt Geórgia Campos Sales Neto Ariela Milbrath Cardoso Suzana Frighetto Ferrarini Marçal José Rodrigues Pires 《应用聚合物科学杂志》2021,138(7):49842
The use of polymeric films incorporated with zeolite-TiO2 composites associated with UV radiation can be an alternative in the removal of volatile organic compounds (VOCs) through the adsorption and photodegradation processes. This study produced poly(lactic acid) (PLA) films incorporated with 13× zeolite, TiO2, and 13×-TiO2 zeolite composite to remove n-butanol and evaluate the by-products generated in the process. The results showed that 13× zeolite and TiO2 added individually or as a composite to PLA, gave the polymer matrix a significant increase in the removal capacity of n-butanol. The best performance was presented by the zeolite-TiO2, composite, confirming a synergistic effect. However, the formation of CO and CO2 exceeded the expected values, with the verification that the polymeric matrix underwent photodegradation action by TiO2. The polymeric film only containing zeolite is the most suitable for the removal of VOCs, as it did not present degradation of the PLA, generating a lower concentration of by-products. 相似文献
86.
Alejandro Ávila-Ortega José Pablo Avalos-Hernández Rudy Trejo-Tzab Andrés Iván Oliva Juan Antonio Juárez-Moreno 《应用聚合物科学杂志》2021,138(30):50737
Among several oil/water emulsion separation technologies, the utilization of nanoparticle-decorated membranes with diverse functionalities has received considerable attention in recent years, particularly if the antifouling capacity can be improved. In this article, we propose a new membrane based on surface-hydrolyzed polyacrylonitrile electrospun membranes and/or decorated with amine-functionalized Si-MCM-41 nanoparticles to be used as oil/water emulsion separation treatment and to determine their antifouling ability. X-Ray photoelectron spectrometry, attenuated total reflectance Fourier transform infrared spectroscopy, and toluidine blue O assay, scanning electron microscopy, contact angle measurements for oil under water and thermogravimetry were used for characterizing the membranes and an assay of permeability was developed to quantify the diffusion of oil molecules across the electrospun membrane. The electrospun and/or decorated membranes showed an underwater oleophobic wettability, which can separate oil-in-water emulsions with 87% separation efficiency, results of fouling experiments, evaluated in terms of rejection and flux recovery ratio, exhibited good antifouling ability, but the membrane decoration process did not lead to superior outcomes compared with undecorated membranes. 相似文献
87.
A model for atmospheric pollutant transport is proposed considering an advection–diffusion–reaction equation. A splitting method is used to decouple the advection, diffusion and reaction parts. A scheme based on finite volume, finite difference and backward differentiation formula is used for solving an atmospheric transport-chemistry problem. 相似文献
88.
Inspired by the relational algebra of data processing, this paper addresses the foundations of data analytical processing from a linear algebra perspective. The paper investigates, in particular, how aggregation operations such as cross tabulations and data cubes essential to quantitative analysis of data can be expressed solely in terms of matrix multiplication, transposition and the Khatri–Rao variant of the Kronecker product. The approach offers a basis for deriving an algebraic theory of data consolidation, handling the quantitative as well as qualitative sides of data science in a natural, elegant and typed way. It also shows potential for parallel analytical processing, as the parallelization theory of such matrix operations is well acknowledged. 相似文献
89.
90.
José Hernández-Orallo Cèsar Ferri Nicolas Lachiche Adolfo Martínez-Usó M. José Ramírez-Quintana 《Data mining and knowledge discovery》2016,30(4):848-890
Some supervised tasks are presented with a numerical output but decisions have to be made in a discrete, binarised, way, according to a particular cutoff. This binarised regression task is a very common situation that requires its own analysis, different from regression and classification—and ordinal regression. We first investigate the application cases in terms of the information about the distribution and range of the cutoffs and distinguish six possible scenarios, some of which are more common than others. Next, we study two basic approaches: the retraining approach, which discretises the training set whenever the cutoff is available and learns a new classifier from it, and the reframing approach, which learns a regression model and sets the cutoff when this is available during deployment. In order to assess the binarised regression task, we introduce context plots featuring error against cutoff. Two special cases are of interest, the \( UCE \) and \( OCE \) curves, showing that the area under the former is the mean absolute error and the latter is a new metric that is in between a ranking measure and a residual-based measure. A comprehensive evaluation of the retraining and reframing approaches is performed using a repository of binarised regression problems created on purpose, concluding that no method is clearly better than the other, except when the size of the training data is small. 相似文献