全文获取类型
收费全文 | 91301篇 |
免费 | 607篇 |
国内免费 | 484篇 |
专业分类
化学 | 26914篇 |
晶体学 | 801篇 |
力学 | 6909篇 |
综合类 | 2篇 |
数学 | 32374篇 |
物理学 | 15608篇 |
无线电 | 9784篇 |
出版年
2023年 | 35篇 |
2022年 | 111篇 |
2021年 | 154篇 |
2020年 | 190篇 |
2019年 | 248篇 |
2018年 | 11971篇 |
2017年 | 11532篇 |
2016年 | 7255篇 |
2015年 | 1119篇 |
2014年 | 678篇 |
2013年 | 923篇 |
2012年 | 4531篇 |
2011年 | 11939篇 |
2010年 | 7055篇 |
2009年 | 6977篇 |
2008年 | 7382篇 |
2007年 | 9776篇 |
2006年 | 339篇 |
2005年 | 1639篇 |
2004年 | 1840篇 |
2003年 | 2222篇 |
2002年 | 1117篇 |
2001年 | 272篇 |
2000年 | 312篇 |
1999年 | 170篇 |
1998年 | 203篇 |
1997年 | 149篇 |
1996年 | 208篇 |
1995年 | 128篇 |
1994年 | 83篇 |
1993年 | 99篇 |
1992年 | 63篇 |
1991年 | 67篇 |
1990年 | 55篇 |
1989年 | 67篇 |
1988年 | 64篇 |
1987年 | 64篇 |
1986年 | 63篇 |
1985年 | 54篇 |
1984年 | 50篇 |
1983年 | 43篇 |
1982年 | 44篇 |
1981年 | 41篇 |
1980年 | 50篇 |
1979年 | 48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 0 毫秒
11.
Moazzeni Shadi Khayyambashi Mohammad Reza Movahhedinia Naser 《Wireless Personal Communications》2019,109(1):645-656
Wireless Personal Communications - Software-Defined Networks (SDNs) are developed to compensate the complicated function of the controlling parts of the given network elements and making the... 相似文献
12.
Behnam Reza Roghani-Mamaqani Hossein Salami-Kalajahi Mehdi 《Journal of Thermal Analysis and Calorimetry》2019,135(6):3311-3319
Journal of Thermal Analysis and Calorimetry - Effect of different chain extenders, silica nanoparticle loading, and using sol–gel method on the thermal properties of polyurethane (PU) hybrid... 相似文献
13.
Correction to: Cloud-based vehicular networks: a taxonomy,survey, and conceptual hybrid architecture
Jabbarpour Mohammad Reza Marefat Alireza Jalooli Ali Zarrabi Houman 《Wireless Networks》2019,25(2):913-913
Wireless Networks - The original version of this article unfortunately contained a mistake in the title. The correct title has been published with this erratum. 相似文献
14.
15.
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
16.
Multivariate curve resolution methods, frequently used in analyzing bilinear data sets, result in ambiguous decomposition in general. Implementing the adequate constraints may lead to reduce the so-called rotational ambiguity drastically, and in the most favorable cases to the unique solution. However, in some special cases, non-negativity constraint as minimal information of the system is a sufficient condition to resolve profiles uniquely. Although, several studies on exploring the uniqueness of the bilinear non-negatively constrained multivariate curve resolution methods have been made in the literature, it has still remained a mysterious question. In 1995, Manne published his profile-based theorems giving the necessary and sufficient conditions of the unique resolution. In this study, a new term, i.e., data-based uniqueness is defined and investigated in details, and a general procedure is suggested for detection of uniquely recovered profile(s) on the basis of data set structure in the abstract space. Close inspection of Borgen plots of these data sets leads to realize the comprehensive information of local rank, and these argumentations furnish a basis for data-based uniqueness theorem. The reported phenomenon and its exploration is a new stage (it can be said fundament) in understanding and describing the bilinear (matrix-type) chemical data in general. 相似文献
17.
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
18.
19.