全文获取类型
收费全文 | 10430篇 |
免费 | 1970篇 |
国内免费 | 259篇 |
专业分类
电工技术 | 67篇 |
综合类 | 242篇 |
化学工业 | 4412篇 |
金属工艺 | 406篇 |
机械仪表 | 232篇 |
建筑科学 | 70篇 |
矿业工程 | 28篇 |
能源动力 | 702篇 |
轻工业 | 587篇 |
水利工程 | 11篇 |
石油天然气 | 124篇 |
武器工业 | 7篇 |
无线电 | 1254篇 |
一般工业技术 | 4215篇 |
冶金工业 | 123篇 |
原子能技术 | 47篇 |
自动化技术 | 132篇 |
出版年
2024年 | 68篇 |
2023年 | 422篇 |
2022年 | 487篇 |
2021年 | 709篇 |
2020年 | 692篇 |
2019年 | 649篇 |
2018年 | 706篇 |
2017年 | 727篇 |
2016年 | 719篇 |
2015年 | 709篇 |
2014年 | 854篇 |
2013年 | 986篇 |
2012年 | 756篇 |
2011年 | 899篇 |
2010年 | 585篇 |
2009年 | 644篇 |
2008年 | 569篇 |
2007年 | 418篇 |
2006年 | 365篇 |
2005年 | 264篇 |
2004年 | 126篇 |
2003年 | 106篇 |
2002年 | 61篇 |
2001年 | 44篇 |
2000年 | 50篇 |
1999年 | 19篇 |
1998年 | 8篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1985年 | 1篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Panagiotis Dallas Radek Zboril Athanasios B. Bourlinos Dalibor Jancik Dimitrios Niarchos Ales Panacek Dimitrios Petridis 《大分子材料与工程》2010,295(2):108-114
The synthesis of silver nanoparticles attached on the surface of a hollow cornet‐like polymer matrix which served as a reductant and host matrix is described. This hybrid organic/inorganic macromolecular matrix is exhibiting anion‐exchange properties, porous structure and hollow morphologies, and absorptions in the visible light region. Due to the anion‐exchange property and the 3D orientation of the macromolecular chains the material is defining a new functional organic/inorganic hybrid. For the synthesis of nanoparticles, no other reducing agents were used and silver nanoparticles with a mean diameter of less than 20 nm were attached on the surface of the polymer, thus inheriting the composite with high antibacterial activity tested in bacterial strains and yeasts.
992.
Hazem Khalil Hans‐Jürgen Gläsel Karl Köhler Ferdinand Hardinghaus Michael R. Buchmeiser 《大分子材料与工程》2010,295(3):276-282
Acrylate‐based nanocomposite coatings prepared from uniformly sized, nanoscaled inorganic, i.e., BaSO4‐ and CaF2‐ as well as organometallic, i.e., Al‐maleate‐derived nanoparticles were prepared applying photochemical curing. Excellent mechanical and thermal stability as well as high optical transparency was achieved as compared to standard SiO2‐based coatings. The performance of CaF2‐based nanocomposites could be further enhanced by addition of nanocorundum. A comprehensive data set on surface and Martens hardness, the penetration depths, glass transition temperatures, and UV–Vis transparency of the final coatings is presented.
993.
Jian‐Tao Zhang Gang Wei Thomas F. Keller Hilary Gallagher Christian Stötzel Frank A. Müller Michael Gottschaldt Ulrich S. Schubert Klaus D. Jandt 《大分子材料与工程》2010,295(11):1049-1057
The aims of the current study were to synthesize new responsive polymeric microgels with embedded silver nanoparticles and then to employ these particles as catalyst for reduction reactions. To these ends, stimuli‐responsive microgels from PNIPAAm and the chitosan derivative were firstly synthesized by free radical precipitation polymerization. Then, silver nanoparticles were synthesized inside these microgel networks by in situ reduction of AgNO3. These microgels were temperature/pH sensitive with a phase transition temperature of 32–35 °C in water at pH = 3 and 8, respectively. The catalytic activity of the Ag nanoparticles for the reduction of 4‐nitrophenol can be tuned through the swelling or collapse of the responsive microgel network hosting the active nanoparticles.
994.
Siddiqui MR Alshehri S Warad IKh Abd El-Salam NM Mahfouz RM 《International journal of molecular sciences》2010,11(9):3600-3609
Kinetic studies for the non-isothermal decomposition of unirradiated and γ-irradiated silver acetate with 10(3) kGy total γ-ray doses were carried out in air. The results showed that the decomposition proceeds in one major step in the temperature range of (180-270 °C) with the formation of Ag(2)O as solid residue. The non-isothermal data for un-irradiated and γ-irradiated silver acetate were analyzed using Flynn-Wall-Ozawa (FWO) and nonlinear Vyazovkin (VYZ) iso-conversional methods. These free models on the investigated data showed a systematic dependence of Ea on α indicating a simple decomposition process. No significant changes in the thermal decomposition behavior of silver acetate were recorded as a result of γ-irradiation. Calcinations of γ-irradiated silver acetate (CH(3)COOAg) at 200 °C for 2 hours only led to the formation of pure Ag(2)O mono-dispersed nanoparticles. X-ray diffraction, FTIR and SEM techniques were employed for characterization of the synthesized nanoparticles. 相似文献
995.
This review presents the state of the art regarding the improvement of scratch resistance of polymeric coatings. In particular, our attention is focused on the effect of inorganic nanometric fillers on the scratch resistance of organic coatings. Two main strategies are described for the achievement of such nanostructured hybrid organic/inorganic coatings: either a top‐down or a bottom‐up approach.
996.
Kalayil Manian Manesh Anantha Iyengar GopalanShanmugasundaram Komathi 《Catalysis communications》2010,11(10):913-918
A novel organic–inorganic hybrid nanocatalyst, Ag nanoparticles supported poly[N-(3-Trimethoxy silyl)propyl]aniline (Ag@PTMSPA), was prepared by a simple one-step method. X-ray diffraction analysis, field emission transmission electron microscopy and X-ray photo electron spectroscopy reveal the coexistence of Ag nanoparticles (average size ∼ 10 nm) and PTMSPA in Ag@PTMSPA. N2 adsorption–desorption experiments provide the textural properties of the catalyst, such as surface area (86.6 m2/g), pore volume (1.3 × 10− 1 cm3/g) and pore size (4.2 nm). UV–visible spectroscopy was used to follow the kinetics of reduction of 4-nitrophenol (4-NP) by sodium borohydride (NaBH4) in the presence of Ag@PTMSPA catalyst. 相似文献
997.
998.
KH570用量对纳米SiO_2接枝改性的影响 总被引:3,自引:0,他引:3
以乙醇和水混合液作为分散介质,采用硅烷偶联剂KH570对纳米二氧化硅(Nano-SiO2)进行接枝改性,制备了KH570接枝改性纳米SiO(2Nano-SiO2-g-KH570)。采用红外光谱、粒度分析及亲油化度测试,研究了KH570用量对Nano-SiO2改性效果的影响。结果表明,以乙醇和水混合液为分散介质,KH570可以对Nano-SiO2进行接枝改性;KH570用量对Nano-SiO2-g-KH570的粒径、粒径分布及亲油化度有明显的影响:KH570用量为5%时,Nano-SiO2-g-KH570的粒径最小,为103nm,粒径分布较窄,亲油化度为32%。 相似文献
999.
Solid-state polymer electrolytes (SPEs) have attracted significant attention owing to their improvement in high energy density and high safety performance. However, the low lithium-ion conductivity of SPEs at room temperature restricts their further application in lithium-ion batteries (LIBs). Herein, we propose a novel poly (ethylene oxide) (PEO)-based nanocomposite polymer electrolytes by blending boron-containing nanoparticles (BNs) in the PEO matrix (abbreviated as: PEO/BNs NPEs). The boron atom of BNs is sp2-hybridized and contains an empty p-orbital that can interact with the anion of lithium salt, promoting the dissociation of the lithium salts. In addition, the introduction of the BNs could reduce the crystallinity of PEO. And thus, the ionic conductivity of PEO/BNs NPEs could reach as high as 1.19 × 10−3 S cm−1 at 60°C. Compared to the pure PEO solid polymer electrolyte (PEO SPEs), the PEO/BNs NPEs showed a wider electrochemical window (5.5 V) and larger lithium-ion migration number (0.43). In addition, the cells assembled with PEO/BNs NPEs exhibited good cycle performance with an initial discharge capacity of 142.5 mA h g−1 and capacity retention of 87.7% after 200 cycles at 2 C (60°C). 相似文献
1000.
Xiang Wang Zhifeng Zhou Guicun Qi Binghai Li Zhihai Song Xiaohong Zhang 《Polymer Engineering and Science》2023,63(2):615-622
Elastomeric nanoparticles (ENPs) are rubber nanoparticles that have different effects than carbon black (CB) when added to rubber composites. To further understand the effects of ENPs on rubber composites, the morphologies, viscoelasticity, mechanical properties, and interactions with rubber were carefully studied. The results revealed that ENPs and CB differed in terms of their dispersion states and reinforcing effects on rubber. The addition of ENPs can reduce the free chain ends of rubber composites, which helps reduce the rolling resistance, making it a possible way to develop energy-saving tires. Compared with current techniques for lowering the free chain ends of vulcanisates, it is easier and simpler to add ENPs to rubber composites. The results also show that ENPs and CB had a synergistic effect on rubber reinforcement. The optimal ENP content, considering the vulcanisate characteristics, was approximately 10 phr. 相似文献