全文获取类型
收费全文 | 26503篇 |
免费 | 4530篇 |
国内免费 | 3335篇 |
专业分类
化学 | 13178篇 |
晶体学 | 281篇 |
力学 | 1128篇 |
综合类 | 188篇 |
数学 | 2102篇 |
物理学 | 7546篇 |
无线电 | 9945篇 |
出版年
2024年 | 84篇 |
2023年 | 638篇 |
2022年 | 784篇 |
2021年 | 1037篇 |
2020年 | 1055篇 |
2019年 | 1042篇 |
2018年 | 914篇 |
2017年 | 884篇 |
2016年 | 1192篇 |
2015年 | 1323篇 |
2014年 | 1527篇 |
2013年 | 1907篇 |
2012年 | 2409篇 |
2011年 | 2412篇 |
2010年 | 1822篇 |
2009年 | 1828篇 |
2008年 | 1915篇 |
2007年 | 1738篇 |
2006年 | 1538篇 |
2005年 | 1318篇 |
2004年 | 974篇 |
2003年 | 807篇 |
2002年 | 703篇 |
2001年 | 639篇 |
2000年 | 573篇 |
1999年 | 557篇 |
1998年 | 396篇 |
1997年 | 344篇 |
1996年 | 330篇 |
1995年 | 281篇 |
1994年 | 271篇 |
1993年 | 196篇 |
1992年 | 189篇 |
1991年 | 173篇 |
1990年 | 130篇 |
1989年 | 83篇 |
1988年 | 80篇 |
1987年 | 55篇 |
1986年 | 41篇 |
1985年 | 47篇 |
1984年 | 34篇 |
1983年 | 37篇 |
1982年 | 18篇 |
1981年 | 12篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1974年 | 4篇 |
1966年 | 3篇 |
1957年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
1.
2.
Let p ∈ [1, ∞), q ∈ [1, ∞), α∈ R, and s be a non-negative integer. Inspired by the space JNp introduced by John and Nirenberg(1961) and the space B introduced by Bourgain et al.(2015), we introduce a special John-Nirenberg-Campanato space JNcon(p,q,s) over Rn or a given cube of R;with finite side length via congruent subcubes, which are of some amalgam features. The limit space of such spaces as p →∞ is just the Campanato space which coincides with the space BMO(the space of functions with bounded mean oscillations)when α = 0. Moreover, a vanishing subspace of this new space is introduced, and its equivalent characterization is established as well, which is a counterpart of the known characterization for the classical space VMO(the space of functions with vanishing mean oscillations) over Rn or a given cube of Rn with finite side length.Furthermore, some VMO-H1-BMO-type results for this new space are also obtained, which are based on the aforementioned vanishing subspaces and the Hardy-type space defined via congruent cubes in this article. The geometrical properties of both the Euclidean space via its dyadic system and congruent cubes play a key role in the proofs of all these results. 相似文献
3.
Zeng Qing-Wei Wen Zhuo-Yu Fu Jun-Feng Zhou Nan-Run 《International Journal of Theoretical Physics》2021,60(9):3306-3333
International Journal of Theoretical Physics - A new quantum watermark algorithm is presented by combining maximum pixel difference partitioning with the least significant bit substitution... 相似文献
4.
氢脆具有很强的微观组织敏感性,威胁着各类高强结构材料的安全服役.采用激光-电弧复合焊工艺对BS960E型高强钢进行焊接,并对接头在原位电化学充氢的条件下进行慢应变速率(10-5s-1)拉伸试验,结合微观组织和断裂特征进行分析并对接头的氢脆行为进行研究.结果 表明,焊接热循环所形成的富马氏体中的细晶区可以使接头表现出一定的氢脆敏感性,马氏体较大的氢扩散系数和较低的氢溶解度以及氢在晶界上的快速扩散是引起接头对氢脆敏感的主要原因,通过控制焊接工艺参数可抑制焊接热循环所引起的马氏体转变量,能够降低BS960E型高强钢激光-电弧复合焊接头的氢脆敏感性. 相似文献
5.
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
6.
Mathematical Programming - We seek tight bounds on the viable parallelism in asynchronous implementations of coordinate descent that achieves linear speedup. We focus on asynchronous coordinate... 相似文献
7.
Interactions of the vector breathers for the coupled Hirota system with $$4\times 4$$ 4 × 4 Lax pair
Nonlinear Dynamics - In this paper, we investigate the interactions of the vector breathers for the coupled Hirota system with $$4\times 4$$ Lax pair. Firstly, we give the first-order breather... 相似文献
8.
We consider concentrated vorticities for the Euler equation on a smooth domain in the form of supported on well-separated vortical domains , , of small diameters . A conformal mapping framework is set up to study this free boundary problem with being part of unknowns. For any given vorticities and small , through a perturbation approach, we obtain such piecewise constant steady vortex patches as well as piecewise smooth Lipschitz steady vorticities, both concentrated near non-degenerate critical configurations of the Kirchhoff–Routh Hamiltonian function. When vortex patch evolution is considered as the boundary dynamics of , through an invariant subspace decomposition, it is also proved that the spectral/linear stability of such steady vortex patches is largely determined by that of the 2N-dimensional linearized point vortex dynamics, while the motion is highly oscillatory in the 2N-codim directions corresponding to the vortical domain shapes. 相似文献
9.
Dr. Qing Xu Dr. Shanshan Tao Dr. Qiuhong Jiang Prof. Donglin Jiang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(11):4587-4593
A strategy based on covalent organic frameworks for ultrafast ion transport involves designing an ionic interface to mediate ion motion. Electrolyte chains were integrated onto the walls of one-dimensional channels to construct ionic frameworks via pore surface engineering, so that the ionic interface can be systematically tuned at the desired composition and density. This strategy enables a quantitative correlation between interface and ion transport and unveils a full picture of managing ionic interface to achieve high-rate ion transport. Moreover, the effect of interfaces was scaled on ion transport; ion mobility is increased in an exponential mode with the ionic interface. This strategy not only sets a benchmark system but also offers a general guidance for designing ionic interface that is key to systems for energy conversion and storage. 相似文献
10.