全文获取类型
收费全文 | 1465篇 |
免费 | 77篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 17篇 |
综合类 | 4篇 |
化学工业 | 446篇 |
金属工艺 | 26篇 |
机械仪表 | 42篇 |
建筑科学 | 45篇 |
矿业工程 | 9篇 |
能源动力 | 39篇 |
轻工业 | 217篇 |
水利工程 | 15篇 |
石油天然气 | 8篇 |
无线电 | 69篇 |
一般工业技术 | 233篇 |
冶金工业 | 112篇 |
原子能技术 | 3篇 |
自动化技术 | 258篇 |
出版年
2024年 | 6篇 |
2023年 | 11篇 |
2022年 | 60篇 |
2021年 | 85篇 |
2020年 | 57篇 |
2019年 | 54篇 |
2018年 | 70篇 |
2017年 | 72篇 |
2016年 | 69篇 |
2015年 | 55篇 |
2014年 | 59篇 |
2013年 | 114篇 |
2012年 | 102篇 |
2011年 | 109篇 |
2010年 | 91篇 |
2009年 | 109篇 |
2008年 | 65篇 |
2007年 | 60篇 |
2006年 | 55篇 |
2005年 | 29篇 |
2004年 | 19篇 |
2003年 | 31篇 |
2002年 | 24篇 |
2001年 | 12篇 |
2000年 | 6篇 |
1999年 | 12篇 |
1998年 | 27篇 |
1997年 | 24篇 |
1996年 | 11篇 |
1995年 | 9篇 |
1994年 | 11篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1977年 | 1篇 |
1973年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有1543条查询结果,搜索用时 15 毫秒
71.
Elton Joao Zierhut Rodrigo Battisti Ricardo Antonio Francisco Machado Cintia Marangoni 《化学工程与技术》2020,43(9):1884-1896
Intrinsic characteristics of distillation such as dead time and high nonlinearities do not allow the complete elimination of transient times when any external disturbance or set-point change occurs. Thus, aiming at the use of easy-tuning systems, a distributed-action control in trays of a diabatic distillation unit with Smith's predictor was implemented in the Simulink environment to further reduce transient times and out-of-specification product. The distributed-action strategy with Smith's predictor led to a reduction of 33.3 min (33 %) in the transient time of the top temperature control loop and 66 % in out-of-specification product, when compared with the conventional strategy, and thus is shown to be an efficient approach to increasing the productivity of distillation plants. 相似文献
72.
Frida S. Herrera-Vázquez Dr. Félix Matadamas-Martínez Dr. Rodrigo Aguayo-Ortiz Prof. Laura Dominguez Teresa Ramírez-Apan Prof. Lilián Yépez-Mulia Prof. Francisco Hernández-Luis 《ChemMedChem》2020,15(19):1802-1812
Microtubules are highly dynamic polymers composed of α- and β-tubulin proteins that have been shown to be potential therapeutic targets for the development of anticancer drugs. Currently, a wide variety of chemically diverse agents that bind to β-tubulin have been reported. Nocodazole (NZ) and colchicine (COL) are well-known tubulin-depolymerizing agents that have close binding sites in the β-tubulin. In this study, we designed and synthesized a set of nine 2,4-diaminoquinazoline derivatives that could occupy both NZ and COL binding sites. The synthesized compounds were evaluated for their antiproliferative activities against five cancer cell lines (PC-3, HCT-15, MCF-7, MDA-MB-231, and SK-LU-1), a noncancerous one (COS-7), and peripheral blood mononuclear cells (PBMC). The effect of compounds 4 e and 4 i on tubulin organization and polymerization was analyzed on the SK-LU-1 cell line by indirect immunofluorescence, western blotting, and tubulin polymerization assays. Our results demonstrated that both compounds exert their antiproliferative activity by inhibiting tubulin polymerization. Finally, a possible binding pose of 4 i in the NZ/COL binding site was determined by using molecular docking and molecular dynamics (MD) approaches. To our knowledge, this is the first report of non-N-substituted 2,4-diaminoquinazoline derivatives with the ability to inhibit tubulin polymerization. 相似文献
73.
This work reports the study of four different carbon materials for their application as carbon material in microporous layers for high temperature proton exchange membrane fuel cells electrodes. The microporous layers were prepared with carbon black (a commercial one, Vulcan XC72), two different carbon nanofibers, CNF, (Ribbon and Platelet structure) and carbon nanospheres, all of them prepared in our lab. The microporous layers were characterized by XRD. The hydrophobicity, electrical conductivity, and permeability to different gases were also evaluated. The stability is an important issue to be overcome in the field of proton exchange membrane fuel cells. Thus, accelerated thermal and electrochemical degradation tests in phosphoric acid media were carried out to evaluate the stability of the different advanced materials tested under the same conditions. From all the performed essays, the carbon nanospheres were the best nano‐carbon materials because of the lower degradation degree shown by the microporous layer prepared with them and the good conductivity and permeability achieved, whereas CNF with a Platelet structure showed a low electrochemical stability due to their greater edge plane exposure which favors their corrosion. 相似文献
74.
Towards the scale‐up of electrolysis with diamond anodes: effect of stacking on the electrochemical oxidation of 2,4 D 下载免费PDF全文
75.
76.
77.
78.
Paola Cristina Cajas Daza Rodrigo Arbey Muñoz Meneses Ana Candida Martins Rodrigues Cosme Roberto Moreira da Silva 《Ceramics International》2018,44(12):13699-13705
Doped CeGdO and codoped CeGdOSmO compositions were synthesized, giving rise to nanoparticulate powders. Ionic conductivities at bulk and grain boundaries of the sintered samples were determined, exhibiting increased conductivity in the samaria-codoped samples. Scanning electron microscopy (SEM) showed a significant reduction in the grain size of samaria-codoped electrolytes. This reduced grain size of the codoped samples caused a reduction in Schottky barrier height, increasing oxygen vacancy concentration in the space-charge layer of the grain boundary and culminating in greater ionic conductivity in the boundary region. For the gadolinium doped samples, high resolution transmission electron microscopy images at grains showed the presence of large cluster of defects (nanodomains), hindering the movement of charge carriers and reducing ionic conductivity. However, the samaria-codoped system displayed better homogeneity at atomic level, resulting in reduced oxygen vacancy ordering and, consequently, smaller nanodomains and higher bulk (grain) conductivity. The reduced grain sizes and smaller nanodomains caused by codoping favor the ionic conductivity of ceria-based ceramics, doped with gadolinia and codoped with samaria. 相似文献
79.
María J. Martín de Vidales José Robles‐Molina Juan C. Domínguez‐Romero Pablo Cañizares Cristina Sáez Antonio Molina‐Díaz Manuel A. Rodrigo 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(10):1441-1449
BACKGROUND: Sulfamethoxazole (SMX, used as a model bacteriostatic antibiotic) is persistent to conventional biological treatments of wastewaters. In this work, conductive‐diamond electrochemical oxidation (CDEO) was found to be an effective technology for its removal from the effluents of conventional wastewater treatment plants. RESULTS: The use of CDEO has been evaluated for the removal of the antibiotic SMX from water and wastewaters. The results show that CDEO can reduce the concentration of this organic pollutant to values below 0.1 µg dm?3. The variation of the SMX concentration during electrolysis shows a complex shape with a plateau zone that increases in size with the initial concentration of SMX. This complex trend is not observed in the changes of TOC, which seems to indicate that the CDEO of SMX solutions does not lead directly to the generation of carbon dioxide as a final product. A tentative reaction pathway has been proposed based on a thorough analysis of the reaction mixture, in which the main intermediate products were identified. The use of liquid chromatography time‐of‐flight mass spectrometry (LC‐TOFMS) allowed the identification of nine organic intermediates (with Mw 98, 108, 172, 173, 197, 203, 227, 269 and 287) during the electrolysis and the concentration of these compounds depends on the initial SMX concentration and on the current density applied. CONCLUSIONS: CDEO is able to reduce the concentration of the organic pollutant below 0.1 mg dm?3. SMX removal is faster than that of TOC. This fact indicates the formation of reaction intermediates. Analytical techniques show that nine reaction intermediates are generated in the system, and that their concentration depends on the initial SMX concentration and on the current density used. Copyright © 2012 Society of Chemical Industry 相似文献
80.
Bruna A Bregadiolli Hasina H Ramanitra Rodrigo Marques Ferreira Laura Corcoles Milton S Gomes Lauren Kang Craig MS Combe Hugo Santos Silva Francisco C Lavarda Didier Bégué Christine Dagron‐Lartigau Maria Luiza M Rocco Christine K Luscombe Clarissa A Olivati Carlos FO Graeff Roger C Hiorns 《Polymer International》2017,66(10):i-i
The cover image, by Bruna A. Bregadiolli et al., is based on the Research Article Towards the synthesis of poly(azafulleroid)s: main chain fullerene oligomers for organic photovoltaic devices, DOI: 10.1002/pi.5419 .