全文获取类型
收费全文 | 80636篇 |
免费 | 911篇 |
国内免费 | 892篇 |
专业分类
化学 | 26275篇 |
晶体学 | 819篇 |
力学 | 6851篇 |
综合类 | 29篇 |
数学 | 32276篇 |
物理学 | 16189篇 |
出版年
2023年 | 82篇 |
2022年 | 96篇 |
2021年 | 134篇 |
2020年 | 154篇 |
2019年 | 162篇 |
2018年 | 10546篇 |
2017年 | 10359篇 |
2016年 | 6212篇 |
2015年 | 1026篇 |
2014年 | 477篇 |
2013年 | 534篇 |
2012年 | 4027篇 |
2011年 | 10738篇 |
2010年 | 5829篇 |
2009年 | 6239篇 |
2008年 | 6791篇 |
2007年 | 8898篇 |
2006年 | 368篇 |
2005年 | 1431篇 |
2004年 | 1603篇 |
2003年 | 2016篇 |
2002年 | 1079篇 |
2001年 | 288篇 |
2000年 | 336篇 |
1999年 | 209篇 |
1998年 | 219篇 |
1997年 | 191篇 |
1996年 | 256篇 |
1995年 | 174篇 |
1994年 | 118篇 |
1993年 | 129篇 |
1992年 | 71篇 |
1991年 | 89篇 |
1990年 | 64篇 |
1989年 | 71篇 |
1988年 | 68篇 |
1987年 | 60篇 |
1986年 | 63篇 |
1985年 | 49篇 |
1984年 | 43篇 |
1983年 | 37篇 |
1982年 | 42篇 |
1981年 | 38篇 |
1980年 | 47篇 |
1979年 | 44篇 |
1914年 | 45篇 |
1913年 | 40篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
S. V. Panin I. V. Vlasov V. P. Sergeev B. B. Ovechkin P. O. Marushchak Sunder Ramasubbu P. S. Lyubutin V. V. Titkov 《Physical Mesomechanics》2015,18(3):261-272
The structure and properties of 12Cr1MoV steel irradiated with a zirconium ion beam were studied by optical microscopy, scanning electron microscopy, and micro- and nanoindentation. It is shown that the modification covers the entire cross-section of the irradiated specimens to a depth of 1 mm. The data on irradiation-induced structural changes are used to interpret the changes in mechanical properties of the irradiated specimens under static and cyclic loading. Particular attention is given to analysis of strain estimation by the digital image correlation method. 相似文献
12.
He Haidong Yang Haifeng Zhou Longpeng Chen Tianchi 《Journal of Russian Laser Research》2015,36(3):292-299
Ni–Co alloys have a wide range of applications in various fields owning to their excellent physical, chemical, and mechanical properties. In this paper, we prepare Ni–Co alloy coatings on 316L stain steel surfaces by electroplating. We present a novel approach utilizing a nanosecond laser to induce microtextures on Ni–Co alloy coatings. We study experimentally the effects of laser power and scanning rate on the surface morphologies of Ni–Co alloy coatings. The results indicate that the shape and size of induced microtextures can be controlled by the laser power and scanning rate. The size of grains increases with increase in the work current of the laser (WCL) at a certain scanning rate. With the WCL constant, the size of grains decreases with increase in scanning rate while their average height increases. It is a simple and easily-controlled method for the fabrication of microstructures on Ni–Co alloy coatings, which has promising applications in investigations of the properties of microtextured surfaces, such as friction, adhesion, and wetting. 相似文献
13.
14.
15.
16.
Zenon Moszner 《Aequationes Mathematicae》2018,92(4):617-625
We give the form of the output function in Ginsburg’s machine in which the input and output dictionaries are abelian groups and the transition function is of a special form. 相似文献
17.
18.
19.
20.
Lan-Lan Zhang Dr. Wen-Ke Miao Dr. Li-Jun Ren Yu-Kun Yan Dr. Yue Lin Prof. Wei Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(58):13396-13401
Organic polymers and inorganic clusters belong to two different disciplines and have completely different properties and structures. When a cluster is attached to the backbone of a polymer as a pendant, the resultant hybrid polymers (polyclusters) exhibit unique behaviours totally different from those of conventional polymers owing to the nanoscale size of the cluster and its particular interactions. Herein, the aggregation of a poly(polyoxometalate)—a polynorbornene backbone with inorganic polyoxometalate cluster pendants—upon addition of a non-solvent to its dilute solution is reported. A three-dimensional network of tangled and snake-like nanothreads was observed. Direct visualisation of individual nanoscale clusters enabled identification of single chains within the nanothreads. These observations suggest that during the process of aggregation, the hybrid polymer forms curved or extended chains as a consequence of an armouring effect in which the collapsed cluster pendants wrap around the backbone. The collapse occurs because they become less soluble in the solvent/non-solvent mixture. The extended chains then become entwined and form nanoropes consisting of multiple chains wound around each other. This study provides a deeper understanding of the nature of polyclusters and should also prove useful for their future development and application. 相似文献