全文获取类型
收费全文 | 9096篇 |
免费 | 644篇 |
国内免费 | 298篇 |
专业分类
电工技术 | 185篇 |
综合类 | 593篇 |
化学工业 | 5474篇 |
金属工艺 | 316篇 |
机械仪表 | 125篇 |
建筑科学 | 205篇 |
矿业工程 | 201篇 |
能源动力 | 170篇 |
轻工业 | 1136篇 |
水利工程 | 33篇 |
石油天然气 | 338篇 |
武器工业 | 6篇 |
无线电 | 129篇 |
一般工业技术 | 785篇 |
冶金工业 | 231篇 |
原子能技术 | 67篇 |
自动化技术 | 44篇 |
出版年
2024年 | 24篇 |
2023年 | 125篇 |
2022年 | 210篇 |
2021年 | 282篇 |
2020年 | 226篇 |
2019年 | 202篇 |
2018年 | 206篇 |
2017年 | 347篇 |
2016年 | 329篇 |
2015年 | 315篇 |
2014年 | 431篇 |
2013年 | 482篇 |
2012年 | 663篇 |
2011年 | 679篇 |
2010年 | 463篇 |
2009年 | 459篇 |
2008年 | 387篇 |
2007年 | 565篇 |
2006年 | 485篇 |
2005年 | 456篇 |
2004年 | 400篇 |
2003年 | 326篇 |
2002年 | 302篇 |
2001年 | 264篇 |
2000年 | 261篇 |
1999年 | 234篇 |
1998年 | 148篇 |
1997年 | 116篇 |
1996年 | 98篇 |
1995年 | 105篇 |
1994年 | 85篇 |
1993年 | 63篇 |
1992年 | 61篇 |
1991年 | 49篇 |
1990年 | 39篇 |
1989年 | 17篇 |
1988年 | 25篇 |
1987年 | 23篇 |
1986年 | 20篇 |
1985年 | 13篇 |
1984年 | 15篇 |
1983年 | 9篇 |
1982年 | 13篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1955年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
G Garrote J
M Cruz H Domínguez J
C Paraj 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2003,78(4):392-398
Non‐isothermal processing of lignocellulosic materials in aqueous media (autohydrolysis reaction) under mild conditions leads to solutions containing valuable chemicals (oligosaccharides, sugars and acetic acid) and other, undesired, compounds (belonging to the extractive and acid‐soluble lignin fractions) which have to be removed in further purification treatments. Liquors obtained by non‐isothermal autohydrolysis of Eucalyptus globulus wood and corncobs under a variety of operational conditions were extracted with ethyl acetate in order to remove non‐saccharide components, and the suitability of the fraction dissolved in the organic phase was assayed for possible utilisation as an antioxidant. The yield and antioxidant activity of ethyl acetate extracts (measured by the α,α‐diphenyl‐β‐picrylhydrazyl (DPPH) radical scavenging capacity) showed a strong dependence on the autohydrolysis conditions. The antioxidant activity of extracts obtained under selected operational conditions compared well with synthetic antioxidants. © 2003 Society of Chemical Industry 相似文献
2.
3.
JFC磷酸酯的合成和应用 总被引:2,自引:0,他引:2
详述了JFC磷酸酯的合成工艺路线,以及它在织物前处理精练工艺中的应用。与其它磷酸酯类精练剂性能对比,证明它可作为一种性能优良的精练剂中的添加剂。 相似文献
4.
简述国内磷酸二铵的建设情况及不同的生产工艺、原有磷酸二铵装置改造选用的工艺及生产情况 ,重点介绍 Incro工艺在云南红河州磷肥厂年产 12万吨磷铵装置中的改造情况 ,经过比较认为原采用预中和槽流程磷酸二铵装置增产改造时选用 Incro工艺比较合适 相似文献
5.
Poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐para‐phenylene vinylene] (MEH‐PPV)/silica nanoparticle hybrid films were prepared and characterised. Three kinds of materials were compared: parent MEH‐PPV, MEH‐PPV/silica (hybrid A films), and MEH‐PPV/coupling agent MSMA/silica (hybrid B films), in which MSMA is 3‐(trimethoxysilyl) propyl methacrylate. It was found that the hybrid B films could significantly prevent macrophase separation, as evidenced by scanning electron and fluorescence microscopy. Furthermore, the thermal characteristics of the hybrid films were largely improved in comparison with the parent MEH‐PPV. The UV‐visible absorption spectra suggested that the incorporation of MSMA‐modified silica into MEH‐PPV could confine the polymer chain between nanoparticles and thus increase the conjugation length. The photoluminescence (PL) studies also indicated enhancement of the PL intensity and quantum efficiency by incorporating just 2 wt% of MSMA‐modified silica into MEH‐PPV. However, hybrid A films did not show such enhancement of optoelectronic properties as the hybrid B films. The present study suggests the importance of the interface between the luminescent organic polymers and the inorganic silica on morphology and optoelectronic properties. Copyright © 2004 Society of Chemical Industry 相似文献
6.
7.
1Introduction Reconstructivesurgeryisoneofthehottestre searchedsubjectsthatdealingwithbonedefects.Thetra ditionalmethodisimplantationoffreshautograftbonebe causeofitsnon immunoreactiveproperty.Butautologousbonewasnotabundantinsomecases.Sowefoundbeta trica… 相似文献
8.
Lei Liu Ying Kong Hong Xu Jin P. Li Jin X. Dong Zhi Lin 《Microporous and mesoporous materials》2008,115(3):624-628
A three-dimensional zinc phosphate compound with DFT topology, designated as ZnPO4-EU1, has been synthesized by an ionothermal approach from the system HF-ZnO–P2O5-choline chloride-imidazolidone. Ethylenediamine, derived from decomposition of the imidazolidone component of the deep-eutectic solvent (DES) itself, is delivered to the synthesis and serves as an appropriate template for ZnPO4-EU1. Experiments in which the synthesis conditions were varied showed that ZnPO4-EU1 may be prepared over a wide molar ratio of P/Zn = 0.55–13.0. Powder X-ray diffraction patterns have been obtained at intervals to track the crystallization process of this material. The experimental data show that Zn3(PO4)2 · 4H2O (a dense phase) was first isolated from the DES after reaction for 1 h. Subsequently, the pure phase of ZnPO4-EU1 was obtained with increasing crystallization time from 12 h to 72 h. The experimental results show that the nucleation and crystallization take place with relatively low levels of solvent degradation, demonstrating that zinc phosphate with a three-dimensional framework can be synthesized by in situ generation of an appropriate template using an unstable DES at high temperatures (150–200 °C). 相似文献
9.
10.
G. H. Palmir 《Journal of the Institute of Brewing》1987,93(4):332-333
The aleurone cells of barley, wheat, rice, rye, oats and triticale contained, comparatively, higher percentages of phosphorus than the aleurone cells of sorghum, maize or millet. The aleurone tissues of barley, wheat and rice had more phosphate than corresponding tissues of sorghum and maize. Phosphate was not detected in the aleurone tissue of maize but was found in trace amounts in the aleurone tissue of sorghum. 相似文献