全文获取类型
收费全文 | 26862篇 |
免费 | 5330篇 |
国内免费 | 5154篇 |
专业分类
化学 | 19550篇 |
晶体学 | 644篇 |
力学 | 1727篇 |
综合类 | 451篇 |
数学 | 3475篇 |
物理学 | 11499篇 |
出版年
2024年 | 71篇 |
2023年 | 432篇 |
2022年 | 956篇 |
2021年 | 959篇 |
2020年 | 1092篇 |
2019年 | 1075篇 |
2018年 | 945篇 |
2017年 | 993篇 |
2016年 | 1199篇 |
2015年 | 1384篇 |
2014年 | 1665篇 |
2013年 | 2082篇 |
2012年 | 2442篇 |
2011年 | 2527篇 |
2010年 | 1963篇 |
2009年 | 1989篇 |
2008年 | 2196篇 |
2007年 | 1897篇 |
2006年 | 1816篇 |
2005年 | 1505篇 |
2004年 | 1212篇 |
2003年 | 943篇 |
2002年 | 895篇 |
2001年 | 874篇 |
2000年 | 711篇 |
1999年 | 534篇 |
1998年 | 396篇 |
1997年 | 400篇 |
1996年 | 346篇 |
1995年 | 295篇 |
1994年 | 289篇 |
1993年 | 192篇 |
1992年 | 151篇 |
1991年 | 163篇 |
1990年 | 136篇 |
1989年 | 116篇 |
1988年 | 98篇 |
1987年 | 81篇 |
1986年 | 65篇 |
1985年 | 43篇 |
1984年 | 43篇 |
1983年 | 38篇 |
1982年 | 30篇 |
1981年 | 25篇 |
1980年 | 19篇 |
1979年 | 12篇 |
1976年 | 6篇 |
1975年 | 9篇 |
1959年 | 5篇 |
1957年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
931.
932.
借助于伪补和矩阵的幂序列研究了完全完备分配格上矩阵相对于特征值的特征向量的计算方法,利用特征向量的性质证明了最大特征向量的计算公式,并给出了一般特征向量的计算方法. 相似文献
933.
934.
Chen Chen Weng Xinliang Xu Xiao Xia Xiong Xiu Lian Lu Yi Feng Zhou 《Russian Journal of General Chemistry》2013,83(12):2447-2452
We have demonstrated that the fragments of Telaprevir can act as organocatalysts for asymmetric aldol reactions between aromatic aldehydes and acetone under mild conditions. The reaction conditions have been optimized in terms of the catalyst nature, choice of temperature, solvent, additive, and the catalyst loading. Under proper conditions, fairly good yield and enantioselectivity have been achieved. 相似文献
935.
936.
Zhang Han Liu Shang-Hao Liu Feng Yan Shi-Long Li Wei-Yi 《Journal of Thermal Analysis and Calorimetry》2018,132(1):327-336
Journal of Thermal Analysis and Calorimetry - The thermogravimetric techniques and differential thermal analysis have been employed in this work to analyze the macro-reactions mechanism of the... 相似文献
937.
Gurumurthy Dummi Mahadevan Feng Zhao 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(3):1477-1485
Currently, the existing microbial radionuclides transformations processes are not completely understood. Bacteria, however, solubilize radionuclides by direct enzymatic reduction, or indirectly by its metabolites and by facilitating electrochemical redox systems. Microbes exchange electrons from proteins, organelles, metabolites to metals and electrodes have strengthened the novel bioremediation methods. In contrast, MRCs based on this redox behavior has offered considerable value over traditional treatment because of growing renewable and conception of energy incentives methods. Moreover, MRCs provides a flexible platform that enables us to access integrated treatment process of generating power and for recovering valuable resources from the contaminated sites. 相似文献
938.
939.
940.
Wei Zhao Yi Zhang Xiao Wang Xiaowen Hu Feng Liu Thomas P. Russell Guofu Zhou 《Journal of polymer science. Part A, Polymer chemistry》2018,56(20):1369-1375
Block copolymer (BCP) films with long-range lateral ordering and orientation are crucial for many applications. Here, we report a simple, versatile strategy based on a solution casting procedure, to produce millimeter thick film of BCPs with highly oriented nanostructures. Transmission electron microscope (TEM), small angle X-ray scattering (SAXS), and Hansen solubility parameters were used to study the morphology and interactions of the system. A variety of BCP-solvent pairs were investigated. Factors including set-up geometry, BCP characteristics, solvent evaporation, surface tension, and interactions, such as solvent-BCP, solvent-substrate, and BCP-substrate were examined. A mechanism is proposed to describe the observed long-range lateral ordering and orientation in films up to 1 mm in thickness. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 1369–1375 相似文献