全文获取类型
收费全文 | 3805篇 |
免费 | 282篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 66篇 |
综合类 | 3篇 |
化学工业 | 1055篇 |
金属工艺 | 92篇 |
机械仪表 | 119篇 |
建筑科学 | 105篇 |
矿业工程 | 11篇 |
能源动力 | 174篇 |
轻工业 | 689篇 |
水利工程 | 35篇 |
石油天然气 | 27篇 |
无线电 | 231篇 |
一般工业技术 | 672篇 |
冶金工业 | 366篇 |
原子能技术 | 20篇 |
自动化技术 | 430篇 |
出版年
2024年 | 14篇 |
2023年 | 48篇 |
2022年 | 117篇 |
2021年 | 186篇 |
2020年 | 113篇 |
2019年 | 148篇 |
2018年 | 163篇 |
2017年 | 176篇 |
2016年 | 163篇 |
2015年 | 117篇 |
2014年 | 175篇 |
2013年 | 285篇 |
2012年 | 257篇 |
2011年 | 273篇 |
2010年 | 198篇 |
2009年 | 225篇 |
2008年 | 181篇 |
2007年 | 190篇 |
2006年 | 128篇 |
2005年 | 99篇 |
2004年 | 74篇 |
2003年 | 76篇 |
2002年 | 62篇 |
2001年 | 51篇 |
2000年 | 38篇 |
1999年 | 45篇 |
1998年 | 99篇 |
1997年 | 79篇 |
1996年 | 48篇 |
1995年 | 37篇 |
1994年 | 31篇 |
1993年 | 32篇 |
1992年 | 17篇 |
1991年 | 18篇 |
1990年 | 20篇 |
1989年 | 15篇 |
1988年 | 27篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1977年 | 4篇 |
1976年 | 7篇 |
1974年 | 3篇 |
1972年 | 2篇 |
1963年 | 1篇 |
排序方式: 共有4095条查询结果,搜索用时 0 毫秒
1.
2.
Felipe A. Perdomo Siti H. Khalit Claire S. Adjiman Amparo Galindo George Jackson 《American Institute of Chemical Engineers》2021,67(3):e17194
The SAFT-γ Mie group-contribution equation of state is used to represent the fluid-phase behavior of aqueous solutions of a variety of linear, branched, and cyclic amines. New group interactions are developed in order to model the mixtures of interest, including the like and unlike interactions between alkyl primary, secondary, and tertiary amine groups (NH2, NH, N), cyclic secondary and tertiary amine groups (cNH, cN), and cyclic methine-amine groups (cCHNH, cCHN) with water (H2O). The group-interaction parameters are estimated from appropriate experimental thermodynamic data for pure amines and selected mixtures. By taking advantage of the group-contribution nature of the method, one can describe the fluid-phase behavior of mixtures of molecules comprising those groups over broad ranges of temperature, pressure, and composition. A number of aqueous solutions of amines are studied including linear, branched aliphatic, and cyclic amines. Liquid–liquid equilibria (LLE) bounded by lower critical solution temperatures (LCSTs) have been reported experimentally and are reproduced here with the SAFT-γ Mie approach. The main feature of the approach is the ability not only to represent accurately the experimental data employed in the parameter estimation, but also to predict the vapor–liquid, liquid–liquid, and vapor–liquid–liquid equilibria, and LCSTs with the same set of parameters. Pure compound and binary phase diagrams of diverse types of amines and their aqueous solutions are assessed in order to demonstrate the main features of the thermodynamic and fluid-phase behavior. 相似文献
3.
Tallison O. Abreu Roterdan F. Abreu Felipe F. do Carmo Wellington V. de Sousa Helenilson de O. Barros José E.V. de Morais João P.C. do Nascimento Marcelo A.S. da Silva Sergei Trukhanov Alex Trukhanov Larissa Panina Charanjeet Singh Antonio S.B. Sombra 《Ceramics International》2021,47(11):15424-15432
This work presents the dielectric properties of YNbO4 (YNO)–TiO2 composites in the microwave range. X-ray diffraction analysis demonstrates that the addition of TiO2 to YNO results in the formation of a Y(Nb0.5Ti0.5)2O6 phase. In the microwave range, the values of permittivity and dielectric loss did not present major changes with the increment of TiO2. Moreover, the addition of TiO2 results in an improvement in the thermal stability of YNO, with YNO63 demonstrating a resonant frequency of ?8.96 ppm.°C?1. We utilised numerical simulations to evaluate the behaviour of these materials as dielectric resonator antennae and it is found that they exhibit a reflection coefficient below ?10 dB at the resonant frequency, with a realised gain of 4.94 – 5.76 dBi, a bandwidth of 665–1050 MHz and a radiation efficiency above 84%. Our results indicate that YNO–TiO2 composites are interesting candidates for microwave operating devices. 相似文献
4.
5.
6.
7.
8.
9.
P. Carrasqueira H. Rocha J. M. Dias T. Ventura B. C. Ferreira M. C. Lopes 《International Transactions in Operational Research》2023,30(1):206-223
Radiation therapy is a technology-driven cancer treatment modality that has experienced significant advances over the last decades, due to multidisciplinary contributions that include engineering and computing. Recent technological developments allow the use of noncoplanar volumetric modulated arc therapy (VMAT), one of the most recent photon treatment techniques, in clinical practice. In this work, an automated noncoplanar arc trajectory optimization framework designed in two modular phases is presented. First, a noncoplanar beam angle optimization algorithm is used to obtain a set of noncoplanar irradiation directions. Then, anchored in these directions, an optimization strategy is proposed to compute an optimal arc trajectory. The computational experiments considered a pool of twelve difficult head-and-neck tumor cases. It was possible to observe that, for some of these cases, the optimized noncoplanar arc trajectories led to significant treatment planning quality improvements, when compared with coplanar VMAT treatment plans. Although these experiments were done in a research environment treatment planning software (matRad), the conclusions can be of interest for a clinical setting: automated procedures can simplify the current treatment workflow, produce high-quality treatment plans, making better use of human resources and allowing for unbiased comparisons between different treatment techniques. 相似文献
10.
Chitosan microspheres containing bromocresol green, cresol red, and phenolphthalein for corrosion detection, through pH change, are synthesized in order to be used in protective coatings for aluminium alloys. Microspheres containing corrosion detection species are characterized morphologically (SEM) and physico‐chemically (FTIR, TGA). Release studies (UV–vis) are performed in corrosion‐promoting conditions (pH, NaCl), and detection studies by immersion in media associated with corrosion activity while microspheres' sensing activity is evaluated visually. Electrochemical characterization of AA2024 substrates in the presence of chitosan spheres is performed to understand material performance, and a color change is observed as a result of local pH increase in cathodic areas when corrosion takes place. These findings can be correlated with the results from release studies and seem a promising approach for corrosion sensing purposes, not only because pH increase is possible to detect due to corrosion, but also because chitosan is considered an environmentally friendly material. 相似文献