全文获取类型
收费全文 | 104426篇 |
免费 | 15221篇 |
国内免费 | 10911篇 |
专业分类
化学 | 71513篇 |
晶体学 | 1079篇 |
力学 | 6809篇 |
综合类 | 796篇 |
数学 | 13340篇 |
物理学 | 37021篇 |
出版年
2024年 | 88篇 |
2023年 | 1910篇 |
2022年 | 2032篇 |
2021年 | 3107篇 |
2020年 | 3681篇 |
2019年 | 3537篇 |
2018年 | 3211篇 |
2017年 | 2916篇 |
2016年 | 4481篇 |
2015年 | 4459篇 |
2014年 | 5347篇 |
2013年 | 7207篇 |
2012年 | 8768篇 |
2011年 | 9201篇 |
2010年 | 6376篇 |
2009年 | 6233篇 |
2008年 | 6684篇 |
2007年 | 6044篇 |
2006年 | 5636篇 |
2005年 | 4921篇 |
2004年 | 3893篇 |
2003年 | 3032篇 |
2002年 | 2836篇 |
2001年 | 2488篇 |
2000年 | 2222篇 |
1999年 | 2336篇 |
1998年 | 2007篇 |
1997年 | 1757篇 |
1996年 | 1819篇 |
1995年 | 1651篇 |
1994年 | 1476篇 |
1993年 | 1304篇 |
1992年 | 1171篇 |
1991年 | 1044篇 |
1990年 | 863篇 |
1989年 | 742篇 |
1988年 | 589篇 |
1987年 | 526篇 |
1986年 | 463篇 |
1985年 | 475篇 |
1984年 | 320篇 |
1983年 | 255篇 |
1982年 | 220篇 |
1981年 | 178篇 |
1980年 | 141篇 |
1979年 | 105篇 |
1978年 | 97篇 |
1975年 | 88篇 |
1974年 | 89篇 |
1973年 | 100篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
Nonlinear Dynamics - This paper proposes an optimal parameter design of control scheme for mechanical systems by adopting the Stackelberg game theory. The goal of the control is to drive the... 相似文献
32.
Restricted testing conditions were considered recently. For the maximal operator, Hytönen, Li and Sawyer [8] first obtained parental testing condition. Later, they [9] showed that it suffices to restrict testing to doubling cubes. Chen and Lacey [3] gave a similar restricted testing condition. In our paper, we discuss a version of the latter in the multilinear setting.
相似文献33.
低维硅锗材料是制备纳米电子器件的重要候选材料,是研发高效率、低能耗和超高速新一代纳米电子器件的基础材料之一,有着潜在的应用价值。采用密度泛函紧束缚方法分别对厚度相同、宽度在0.272 nm~0.554 nm之间的硅纳米线和宽度在0.283 nm~0.567 nm之间的锗纳米线的原子排布和电荷分布进行了计算研究。硅、锗纳米线宽度的改变使原子排布,纳米线的原子间键长和键角发生明显改变。纳米线表层结构的改变对各层内的电荷分布产生重要影响。纳米线中各原子的电荷转移量与该原子在表层内的位置相关。纳米线的尺寸和表层内原子排列结构对体系的稳定性产生重要影响。 相似文献
34.
We propose a conjecture on the relative twist formula of l-adic sheaves, which can be viewed as a generalization of Kato—Saito's conjecture. We verify this conjecture under some transversal assumptions. We also define a relative cohomological characteristic class and prove that its formation is compatible with proper push-forward. A conjectural relation is also given between the relative twist formula and the relative cohomological characteristic class. 相似文献
35.
Mathematical Programming - Convergence analysis of accelerated first-order methods for convex optimization problems are developed from the point of view of ordinary differential equation solvers. A... 相似文献
36.
Donglei Wei Huili Li Chuanqing Yang Jianmin Fu Hou Chen Liangjiu Bai Wenxiang Wang Huawei Yang Lixia Yang Ying Liang 《Journal of polymer science. Part A, Polymer chemistry》2022,60(10):1588-1594
Acridone as a new kind of visible light photocatalyst has been developed to catalyze metal free atom transfer radical polymerization (ATRP). The photocatalyst possess low excited state potential as can undergo an oxidative quenching pathway to initiate ATRP of vinyl monomers. Kinetic study and light on/off reaction demonstrate the “living”/controlled nature of the polymerization by light. Block copolymers can be achieved by using PMMA as macroinitiator to reinitiate polymerization of other vinyl monomers, which shows highly preserved Br chain-end functionality in the synthesized polymers. Moreover, the polymerization can be conducted under air atmosphere as most photocatalysts need anaerobic condition, which may give inspiration of further application of this kind of photocatalyst. 相似文献
37.
38.
Science China Mathematics - Linear factor models are familiar tools used in many fields. Several pioneering literatures established foundational theoretical results of the quasi-maximum likelihood... 相似文献
39.
Herein, we successfully construct the 3D biocompatible graphene through crosslinking 2D graphene nanosheet onto carbon fiber paper with poly(diallyldimethylammonium chloride) (PDDA) as anode of the alcohol biofuel cell. Compared with the bioanode without 3D graphene, the current density and output power of PDDA-graphene-ADH bioanode is increased by 23 % and 41 % at a high concentration of ethanol at pH 8.9, suggesting the stabilization role of graphene in enzyme loading. The study provides us a deep analysis on structures and performances of the bioanode incl. electrochemistry, X-ray photoelectron spectra, and atomic force microscopy images, which is significant to develop the new methods to construct 3D porous electrodes in energy conversion device. 相似文献
40.