全文获取类型
收费全文 | 41541篇 |
免费 | 6539篇 |
国内免费 | 5290篇 |
专业分类
化学 | 23324篇 |
晶体学 | 447篇 |
力学 | 1496篇 |
综合类 | 266篇 |
数学 | 3267篇 |
物理学 | 10831篇 |
无线电 | 13739篇 |
出版年
2024年 | 196篇 |
2023年 | 1053篇 |
2022年 | 1467篇 |
2021年 | 1759篇 |
2020年 | 1741篇 |
2019年 | 1542篇 |
2018年 | 1397篇 |
2017年 | 1432篇 |
2016年 | 1900篇 |
2015年 | 2176篇 |
2014年 | 2485篇 |
2013年 | 3262篇 |
2012年 | 3742篇 |
2011年 | 3761篇 |
2010年 | 2841篇 |
2009年 | 2795篇 |
2008年 | 2969篇 |
2007年 | 2654篇 |
2006年 | 2502篇 |
2005年 | 2059篇 |
2004年 | 1457篇 |
2003年 | 1205篇 |
2002年 | 1205篇 |
2001年 | 1004篇 |
2000年 | 780篇 |
1999年 | 760篇 |
1998年 | 478篇 |
1997年 | 390篇 |
1996年 | 396篇 |
1995年 | 327篇 |
1994年 | 266篇 |
1993年 | 234篇 |
1992年 | 203篇 |
1991年 | 165篇 |
1990年 | 143篇 |
1989年 | 116篇 |
1988年 | 88篇 |
1987年 | 75篇 |
1986年 | 64篇 |
1985年 | 63篇 |
1984年 | 46篇 |
1983年 | 26篇 |
1982年 | 21篇 |
1981年 | 23篇 |
1980年 | 13篇 |
1979年 | 10篇 |
1976年 | 11篇 |
1975年 | 12篇 |
1971年 | 8篇 |
1957年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Mobile Networks and Applications - Inverse kinematics is an important basic theory in walking control of biped robot. This study focuses on the parameter setting using the improved algorithm in... 相似文献
2.
4.
Wang Rong Li Xu Zhou Youshi Cao Shuxuan Xu Honghao Han Wenjuan Zhang Yuxia Liu Junhai 《Journal of Russian Laser Research》2022,43(4):476-481
Journal of Russian Laser Research - We demonstrate a passively-mode-locked Pr3+: LuLiF4 laser operated at the 604 nm orange wave-length, using monolayer graphene as a saturable absorber. The... 相似文献
5.
Jia Dai Xiang Cheng Xiaofeng Li Zhisheng Wang Yufeng Wang Jing Zheng Jun Liu Jiawei Chen Changjin Wu Jinyao Tang 《Advanced functional materials》2021,31(48):2106204
Synthetic active matters are perfect model systems for non-equilibrium thermodynamics and of great potential for novel biomedical and environmental applications. However, most applications are limited by the complicated and low-yield preparation, while a scalable synthesis for highly functional microswimmers is highly desired. In this paper, an all-solution synthesis method is developed where the gold-loaded titania-silica nanotree can be produced as a multi-functional self-propulsion microswimmer. By applying light, heat, and electric field, the Janus nanotree demonstrated multi-mode self-propulsion, including photochemical self-electrophoresis by UV and visible light radiation, thermophoresis by near-infrared light radiation, and induced-charge electrophoresis under AC electric field. Due to the scalable synthesis, the Janus nanotree is further demonstrated as a high-efficiency, low-cost, active adsorbent for water decontamination, where the toxic mercury ions can be reclaimed with enhanced efficiency. 相似文献
6.
Shuhai Liu Ming Han Xiaolong Feng Qiuhong Yu Long Gu Longfei Wang Yong Qin Zhong Lin Wang 《Advanced functional materials》2021,31(17):2010339
Utilizing inner-crystal piezoelectric polarization charges to control carrier transport across a metal-semiconductor or semiconductor–semiconductor interface, piezotronic effect has great potential applications in smart micro/nano-electromechanical system (MEMS/NEMS), human-machine interfacing, and nanorobotics. However, current research on piezotronics has mainly focused on systems with only one or rather limited interfaces. Here, the statistical piezotronic effect is reported in ZnO bulk composited of nanoplatelets, of which the strain/stress-induced piezo-potential at the crystals’ interfaces can effectively gate the electrical transport of ZnO bulk. It is a statistical phenomenon of piezotronic modification of large numbers of interfaces, and the crystal orientation of inner ZnO nanoplatelets strongly influence the transport property of ZnO bulk. With optimum preferred orientation of ZnO nanoplatelets, the bulk exhibits an increased conductivity with decreasing stress at a high pressure range of 200–400 MPa, which has not been observed previously in bulk. A maximum sensitivity of 1.149 µS m−1 MPa−1 and a corresponding gauge factor of 467–589 have been achieved. As a statistical phenomenon of many piezotronic interfaces modulation, the proposed statistical piezotronic effect extends the connotation of piezotronics and promotes its practical applications in intelligent sensing. 相似文献
7.
A numerical model was developed and validated to investigate the fluid–structure interactions between fully developed pipe flow and core–shell-structured microcapsule in a microchannel. Different flow rates and microcapsule shell thicknesses were considered. A sixth-order rotational symmetric distribution of von Mises stress over the microcapsule shell can be observed on the microcapsule with a thinner shell configuration, especially at higher flow rate conditions. It is also observed that when being carried along in a fully developed pipe flow, the microcapsule with a thinner shell tends to accumulate stress at a higher rate compared to that with a thicker shell. In general, for the same microcapsule configuration, higher flow velocity would induce a higher stress level over the microcapsule shell. The deformation gradient was used to capture the microcapsule's deformation in the present study. The effect of Young's modulus on the microcapsule shell on the microcapsule deformation was investigated as well. Our findings will shed light on the understanding of the stability of core–shell-structured microcapsule when subjected to flow-induced shear stress in a microfluidic system, enabling a more exquisite control over the breakup dynamics of drug-loaded microcapsule for biomedical applications. 相似文献
8.
9.
美军将网络空间视为继陆、海、空、天外的第五大作战域,并将其列为国防部11项现代化优先事项之一,在美国等军事大国推动下,网络空间成为国家安全竞争和军事斗争的新疆域.文中对近年美国联邦政府、各部门及各军种发布的网络空间领域主要战略政策、规划计划进行梳理,研究其主要战略思想;分析美军2022财年国防预算、研究经费投向投量及重点项目的 研发情况.形成的研究成果将对我国网络空间安全领域研究提供技术支撑. 相似文献
10.
Meihua Shen Dr. Xinpeng Zhao Dr. Lu Han Nanxi Jin Prof. Song Liu Prof. Tao Jia Prof. Zhijun Chen Prof. Xiuhua Zhao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(20):e202104137
Solar-driven interfacial vaporization by localizing solar-thermal energy conversion to the air−water interface has attracted tremendous attention. In the process of converting solar energy into heat energy, photothermal materials play an essential role. Herein, a flexible solar-thermal material di-cyan substituted 5,12-dibutylquinacridone (DCN−4CQA)@Paper was developed by coating photothermal quinacridone derivatives on the cellulose paper. The DCN−4CQA@Paper combines desired chemical and physical properties, broadband light-absorbing, and shape-conforming abilities that render efficient photothermic vaporization. Notably, synergetic coupling of solar-steam and solar-electricity technologies by integrating DCN−4CQA@Paper and the thermoelectric devices is realized without trade-offs, highlighting the practical consideration toward more impactful solar heat exploitation. Such solar distillation and low-grade heat-to-electricity generation functions can provide potential opportunities for fresh water and electricity supply in off-grid or remote areas. 相似文献