全文获取类型
收费全文 | 345618篇 |
免费 | 8439篇 |
国内免费 | 4933篇 |
专业分类
化学 | 175599篇 |
晶体学 | 4313篇 |
力学 | 17675篇 |
综合类 | 301篇 |
数学 | 52144篇 |
物理学 | 108958篇 |
出版年
2021年 | 2653篇 |
2020年 | 3146篇 |
2019年 | 3157篇 |
2018年 | 11938篇 |
2017年 | 12722篇 |
2016年 | 9043篇 |
2015年 | 4745篇 |
2014年 | 5549篇 |
2013年 | 11420篇 |
2012年 | 14792篇 |
2011年 | 24165篇 |
2010年 | 15381篇 |
2009年 | 15182篇 |
2008年 | 20874篇 |
2007年 | 23994篇 |
2006年 | 10302篇 |
2005年 | 15352篇 |
2004年 | 11325篇 |
2003年 | 10254篇 |
2002年 | 8173篇 |
2001年 | 7529篇 |
2000年 | 6002篇 |
1999年 | 4485篇 |
1998年 | 3751篇 |
1997年 | 3602篇 |
1996年 | 3634篇 |
1995年 | 3252篇 |
1994年 | 3279篇 |
1993年 | 3058篇 |
1992年 | 3255篇 |
1991年 | 3265篇 |
1990年 | 3013篇 |
1989年 | 2852篇 |
1988年 | 2815篇 |
1987年 | 2732篇 |
1986年 | 2673篇 |
1985年 | 3494篇 |
1984年 | 3546篇 |
1983年 | 2967篇 |
1982年 | 3167篇 |
1981年 | 2915篇 |
1980年 | 2714篇 |
1979年 | 2885篇 |
1978年 | 3108篇 |
1977年 | 3057篇 |
1976年 | 3118篇 |
1975年 | 2852篇 |
1974年 | 2954篇 |
1973年 | 3044篇 |
1972年 | 2354篇 |
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
21.
Hu Duo-Duo Gao Qian Dai Jing-Cheng Cui Ru Li Yuan-Bo Li Yuan-Ming Zhou Xiao-Guo Bian Kang-Jie Wu Bing-Bing Zhang Kai-Fan Wang Xi-Sheng Li Yan 《中国科学:化学(英文版)》2022,65(4):753-761
Science China Chemistry - A light-induced, nickel-catalyzed three-component arylsulfonation of 1,3-enynes in the absence of photocatalyst is reported. This methodology exhibited mild conditions,... 相似文献
22.
Journal of Visualization - The increasing availability of spatiotemporal data provides unprecedented opportunities for understanding the structure of an urban area in terms of people’s... 相似文献
23.
Ukrainian Mathematical Journal - We establish new criteria of compatibility for a linear system of equations (equivalent to the Kronecker–Capelli theorem) or inequalities (equivalent to the... 相似文献
24.
Restricted testing conditions were considered recently. For the maximal operator, Hytönen, Li and Sawyer [8] first obtained parental testing condition. Later, they [9] showed that it suffices to restrict testing to doubling cubes. Chen and Lacey [3] gave a similar restricted testing condition. In our paper, we discuss a version of the latter in the multilinear setting.
相似文献25.
低维硅锗材料是制备纳米电子器件的重要候选材料,是研发高效率、低能耗和超高速新一代纳米电子器件的基础材料之一,有着潜在的应用价值。采用密度泛函紧束缚方法分别对厚度相同、宽度在0.272 nm~0.554 nm之间的硅纳米线和宽度在0.283 nm~0.567 nm之间的锗纳米线的原子排布和电荷分布进行了计算研究。硅、锗纳米线宽度的改变使原子排布,纳米线的原子间键长和键角发生明显改变。纳米线表层结构的改变对各层内的电荷分布产生重要影响。纳米线中各原子的电荷转移量与该原子在表层内的位置相关。纳米线的尺寸和表层内原子排列结构对体系的稳定性产生重要影响。 相似文献
26.
Dzhun I. O. Babaitsev G. V. Kozin M. G. Romashkina I. L. Shanova E. I. Chechenin N. G. 《Physics of the Solid State》2021,63(6):825-831
Physics of the Solid State - The external factors which influence the ferromagnetic resonance (FMR) line width in bilayer (ferromagnet/antiferromagnet) exchange-biased systems are studied. The... 相似文献
27.
Corinne Rondeau-Mouro Mireille Cambert Laurent Blondel Yves Diascorn Léo Mbaya Nor Nadiah Binti Ahmad Nazari Sarah Helary Tiphaine Lucas 《Magnetic resonance in chemistry : MRC》2022,60(7):678-691
A temperature control unit was implemented to vary the temperature of samples studied on a commercial Mobile Universal Surface Explorer nuclear magnetic resonance (MOUSE-NMR) apparatus. The device was miniaturized to fit the maximum MOUSE sampling depth (25 mm). It was constituted by a sample holder sandwiched between two heat exchangers placed below and above the sample. Air was chosen as the fluid to control the temperature at the bottom of the sample, at the interface between the NMR probe and the sample holder, in order to gain space. The upper surface of the sample was regulated by the circulation of water inside a second heat exchanger placed above the sample holder. The feasibility of using such a device was demonstrated first on pure water and then on several samples of bread dough with different water contents. For this, T1 relaxation times were measured at various temperatures and depths and were then compared with those acquired with a conventional compact closed-magnet spectrometer. Discussion of results was based on biochemical transformations in bread dough (starch gelatinization and gluten heat denaturation). It was demonstrated that, within a certain water level range, and because of the low magnetic field strength of the MOUSE, a linear relationship could be established between T1 relaxation times and the local temperature in the dough sample. 相似文献
28.
Chueshova A. G. Pavlova L. A. Peshcherova S. M. Nepomnyashchikh A. I. 《Crystallography Reports》2021,66(7):1206-1215
Crystallography Reports - The orientation of grains and the special boundaries formed by them in multicrystalline silicon has been studied by electron backscattered diffraction. It is found that... 相似文献
29.
Crystallography Reports - Methods of coherent X-ray diffraction imaging of the spatial structure of noncrystalline objects and nanocrystals (nanostructures) are considered. Particular attention is... 相似文献
30.