全文获取类型
收费全文 | 292707篇 |
免费 | 19624篇 |
国内免费 | 10628篇 |
专业分类
化学 | 175780篇 |
晶体学 | 4347篇 |
力学 | 14381篇 |
综合类 | 537篇 |
数学 | 30013篇 |
物理学 | 97901篇 |
出版年
2022年 | 3403篇 |
2021年 | 4496篇 |
2020年 | 5185篇 |
2019年 | 5117篇 |
2018年 | 4625篇 |
2017年 | 4308篇 |
2016年 | 7170篇 |
2015年 | 6306篇 |
2014年 | 8042篇 |
2013年 | 15159篇 |
2012年 | 14163篇 |
2011年 | 15963篇 |
2010年 | 10596篇 |
2009年 | 10244篇 |
2008年 | 12222篇 |
2007年 | 11835篇 |
2006年 | 11127篇 |
2005年 | 9718篇 |
2004年 | 8137篇 |
2003年 | 6950篇 |
2002年 | 6578篇 |
2001年 | 7547篇 |
2000年 | 5995篇 |
1999年 | 5478篇 |
1998年 | 4508篇 |
1997年 | 4422篇 |
1996年 | 4553篇 |
1995年 | 3975篇 |
1994年 | 3804篇 |
1993年 | 3415篇 |
1992年 | 3812篇 |
1991年 | 3611篇 |
1990年 | 3372篇 |
1989年 | 3174篇 |
1988年 | 3017篇 |
1987年 | 2940篇 |
1986年 | 2766篇 |
1985年 | 3569篇 |
1984年 | 3508篇 |
1983年 | 2858篇 |
1982年 | 3030篇 |
1981年 | 2943篇 |
1980年 | 2820篇 |
1979年 | 2930篇 |
1978年 | 3168篇 |
1977年 | 2981篇 |
1976年 | 2922篇 |
1975年 | 2784篇 |
1974年 | 2734篇 |
1973年 | 2739篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
111.
Hierarchical motion planning at the acceleration level based on task priority matrix for space robot
Nonlinear Dynamics - A capacitive micromachined ultrasonic transducer (CMUT) due to many benefits is being considered as an imaging and therapeutic technology recently. The critical challenge is to... 相似文献
112.
Nonlinear Dynamics - Conventional tuned liquid column dampers (TLCDs) are deficient in multidirectionality. In contrast, toroidal TLCDs are designed to extend the application to multidirectional... 相似文献
113.
Acta Mathematica Sinica, English Series - We are interested in the existence and asymptotic behavior for the least energy solutions of the following fractional eigenvalue problem $$\left({\rm{P}}... 相似文献
114.
Chi-Kwong Li Ming-Cheng Tsai Ya-Shu Wang Ngai-Ching Wong 《Journal of Mathematical Analysis and Applications》2022,505(2):125522
Let L be an additive map between (real or complex) matrix algebras sending Hermitian idempotent matrices to Hermitian idempotent matrices. We show that there are nonnegative integers with and an unitary matrix U such that We also extend this result to the (complex) von Neumann algebra setting, and provide a supplement to the Dye-Bunce-Wright Theorem asserting that every additive map of Hermitian idempotents extends to a Jordan ?-homomorphism. 相似文献
115.
Jia Tian-Cong Guo Jin-Tao Wang Zhen Zhu Xiao-Shan Zhang Qian-Xin Chen Ping Yao Kun Lv Wen-Ying Liu Guo-Guang 《Journal of Radioanalytical and Nuclear Chemistry》2019,321(3):823-829
Journal of Radioanalytical and Nuclear Chemistry - In the present work the final products of coumarin radiation chemical transformation are investigated by chromatography. During radiolysis of... 相似文献
116.
Sergio Ayala‐Mar Javier Donoso‐Quezada Roberto C. Gallo‐Villanueva Victor H. Perez‐Gonzalez Jos Gonzlez‐Valdez 《Electrophoresis》2019,40(23-24):3036-3049
Exosomes are nanovesicles secreted by most cellular types that carry important biochemical compounds throughout the body with different purposes, playing a preponderant role in cellular communication. Because of their structure, physicochemical properties and stability, recent studies are focusing in their use as nanocarriers for different therapeutic compounds for the treatment of different diseases ranging from cancer to Parkinson's disease. However, current bioseparation protocols and methodologies are selected based on the final exosome application or intended use and present both advantages and disadvantages when compared among them. In this context, this review aims to present the most important technologies available for exosome isolation while discussing their advantages and disadvantages and the possibilities of being combined with other strategies. This is critical since the development of novel exosome‐based therapeutic strategies will be constrained to the effectiveness and yield of the selected downstream purification methodologies for which a thorough understanding of the available technological resources is needed. 相似文献
117.
Transport in Porous Media - The theme of coupling problems for adsorption, absorption and thermochemical transport in porous media is very important for engineering applications. Based on the... 相似文献
118.
Journal of Thermal Analysis and Calorimetry - The fire behavior of one flame-retardant PVC cable used as building wire is investigated in this work. Bench scale tests were performed using a cone... 相似文献
119.
Differential Equations - We study a mixed problem for systems of one-dimensional semilinear hyperbolic equations with variable nonlinearity growth rate and nonlinear boundary conditions. Theorems... 相似文献
120.
随着经济的飞速发展,社会对能源的需求日益扩大,对工业废水的无害化处理也提出了更高的要求。光催化燃料电池 (photocatalytic fuel cell, PFC) 在燃料电池中引入半导体光催化材料作为电极,实现了有机污染物高效降解和同步对外产电的双重功能,在废水无害化与资源化利用方面具有潜在的应用价值。半导体光催化电极是PFC系统高效运行的核心组件,增强其可见光响应和光生载流子分离是提高PFC性能的关键策略。反应器结构设计和运行参数优化也有利于改善PFC性能。本文从PFC基本原理和应用入手,综述了PFC在环境污染物资源化处理中的研究进展,并详细阐述了提高PFC的污染控制性能和产电效率的优化手段,为进一步设计高效稳定的PFC系统并实现其在水污染控制和清洁能源生产中的应用提供理论指导。 相似文献