全文获取类型
收费全文 | 474289篇 |
免费 | 7197篇 |
国内免费 | 2042篇 |
专业分类
电工技术 | 8855篇 |
综合类 | 393篇 |
化学工业 | 71142篇 |
金属工艺 | 17265篇 |
机械仪表 | 14129篇 |
建筑科学 | 12980篇 |
矿业工程 | 1341篇 |
能源动力 | 12565篇 |
轻工业 | 48408篇 |
水利工程 | 4030篇 |
石油天然气 | 4077篇 |
武器工业 | 54篇 |
无线电 | 60902篇 |
一般工业技术 | 90465篇 |
冶金工业 | 85868篇 |
原子能技术 | 7982篇 |
自动化技术 | 43072篇 |
出版年
2021年 | 3455篇 |
2020年 | 2444篇 |
2019年 | 3138篇 |
2018年 | 5258篇 |
2017年 | 5335篇 |
2016年 | 5752篇 |
2015年 | 4279篇 |
2014年 | 7075篇 |
2013年 | 22280篇 |
2012年 | 12121篇 |
2011年 | 17009篇 |
2010年 | 13241篇 |
2009年 | 15071篇 |
2008年 | 16046篇 |
2007年 | 16372篇 |
2006年 | 14505篇 |
2005年 | 13474篇 |
2004年 | 13027篇 |
2003年 | 12708篇 |
2002年 | 12276篇 |
2001年 | 12463篇 |
2000年 | 11608篇 |
1999年 | 12009篇 |
1998年 | 27004篇 |
1997年 | 19717篇 |
1996年 | 15516篇 |
1995年 | 12204篇 |
1994年 | 10848篇 |
1993年 | 10479篇 |
1992年 | 7941篇 |
1991年 | 7669篇 |
1990年 | 7305篇 |
1989年 | 7021篇 |
1988年 | 6677篇 |
1987年 | 5654篇 |
1986年 | 5622篇 |
1985年 | 6778篇 |
1984年 | 6258篇 |
1983年 | 5488篇 |
1982年 | 5080篇 |
1981年 | 5049篇 |
1980年 | 4781篇 |
1979年 | 4648篇 |
1978年 | 4330篇 |
1977年 | 5225篇 |
1976年 | 6951篇 |
1975年 | 3625篇 |
1974年 | 3510篇 |
1973年 | 3388篇 |
1972年 | 2756篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
81.
Niluka M. Dissanayake Kelley M. Current Sherine O. Obare 《International journal of molecular sciences》2015,16(10):23482-23516
In recent years, there has been an increased interest in the design and use of iron oxide materials with nanoscale dimensions for magnetic, catalytic, biomedical, and electronic applications. The increased manufacture and use of iron oxide nanoparticles (IONPs) in consumer products as well as industrial processes is expected to lead to the unintentional release of IONPs into the environment. The impact of IONPs on the environment and on biological species is not well understood but remains a concern due to the increased chemical reactivity of nanoparticles relative to their bulk counterparts. This review article describes the impact of IONPs on cellular genetic components. The mutagenic impact of IONPs may damage an organism’s ability to develop or reproduce. To date, there has been experimental evidence of IONPs having mutagenic interactions on human cell lines including lymphoblastoids, fibroblasts, microvascular endothelial cells, bone marrow cells, lung epithelial cells, alveolar type II like epithelial cells, bronchial fibroblasts, skin epithelial cells, hepatocytes, cerebral endothelial cells, fibrosarcoma cells, breast carcinoma cells, lung carcinoma cells, and cervix carcinoma cells. Other cell lines including the Chinese hamster ovary cells, mouse fibroblast cells, murine fibroblast cells, Mytilus galloprovincialis sperm cells, mice lung cells, murine alveolar macrophages, mice hepatic and renal tissue cells, and vero cells have also shown mutagenic effects upon exposure to IONPs. We further show the influence of IONPs on microorganisms in the presence and absence of dissolved organic carbon. The results shed light on the transformations IONPs undergo in the environment and the nature of the potential mutagenic impact on biological cells. 相似文献
82.
The Interplay of Modulus,Strength, and Ductility in Adhesive Design Using Biomimetic Polymer Chemistry
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
High‐performance adhesives require mechanical properties tuned to demands of the surroundings. A mismatch in stiffness between substrate and adhesive leads to stress concentrations and fracture when the bonding is subjected to mechanical load. Balancing material strength versus ductility, as well as considering the relationship between adhesive modulus and substrate modulus, creates stronger joints. However, a detailed understanding of how these properties interplay is lacking. Here, a biomimetic terpolymer is altered systematically to identify regions of optimal bonding. Mechanical properties of these terpolymers are tailored by controlling the amount of a methyl methacrylate stiff monomer versus a similar monomer containing flexible poly(ethylene glycol) chains. Dopamine methacrylamide, the cross‐linking monomer, is a catechol moiety analogous to 3,4‐dihydroxyphenylalanine, a key component in the adhesive proteins of marine mussels. Bulk adhesion of this family of terpolymers is tested on metal and plastic substrates. Incorporating higher amounts of poly(ethylene glycol) into the terpolymer introduces flexibility and ductility. By taking a systematic approach to polymer design, the region in which material strength and ductility are balanced in relation to the substrate modulus is found, thereby yielding the most robust joints. 相似文献
83.
84.
Hammons Joshua A. Tumey Scott J. Idell Yaakov Jeffries Jason R. 《JOM Journal of the Minerals, Metals and Materials Society》2020,72(1):176-186
JOM - Alpha-radiation damage in metals is a concern for long-term radioactive storage and systems that produce nuclear energy. Accurate prediction of irradiated material properties and failure... 相似文献
85.
86.
87.
88.
V. I. Zubkov O. V. Kucherova I. N. Yakovlev A. V. Solomonov 《Russian Microelectronics》2015,44(3):203-209
An automated system for integrated electrophysical and optical studies of semiconductor nanoheterostructures, which operates in a wide temperature range from 15 to 475 K, is designed. The setup is intended to measure the temperature and frequency admittance and electroluminescence spectra of light-emitting diode and laser chips formed on substrates of diameter up to 50.2 mm, and the distribution of parameters over the wafer. The setup includes the closed-cycle helium cryogenic station, LCR meter, and temperature controller. The characterization results of nanoheterostructures with InGaN/GaN multiple quantum wells, which are used for creating highly efficient white and blue light-emitting diodes, are presented. 相似文献
89.
90.