全文获取类型
收费全文 | 59877篇 |
免费 | 9966篇 |
国内免费 | 6608篇 |
专业分类
化学 | 42520篇 |
晶体学 | 773篇 |
力学 | 3499篇 |
综合类 | 388篇 |
数学 | 7163篇 |
物理学 | 22108篇 |
出版年
2024年 | 126篇 |
2023年 | 1237篇 |
2022年 | 1729篇 |
2021年 | 2207篇 |
2020年 | 2542篇 |
2019年 | 2415篇 |
2018年 | 2007篇 |
2017年 | 1979篇 |
2016年 | 2940篇 |
2015年 | 2908篇 |
2014年 | 3494篇 |
2013年 | 4402篇 |
2012年 | 5495篇 |
2011年 | 5606篇 |
2010年 | 3865篇 |
2009年 | 3625篇 |
2008年 | 3913篇 |
2007年 | 3416篇 |
2006年 | 3103篇 |
2005年 | 2688篇 |
2004年 | 2080篇 |
2003年 | 1648篇 |
2002年 | 1519篇 |
2001年 | 1235篇 |
2000年 | 1043篇 |
1999年 | 1250篇 |
1998年 | 1002篇 |
1997年 | 914篇 |
1996年 | 930篇 |
1995年 | 851篇 |
1994年 | 730篇 |
1993年 | 588篇 |
1992年 | 498篇 |
1991年 | 456篇 |
1990年 | 401篇 |
1989年 | 291篇 |
1988年 | 214篇 |
1987年 | 187篇 |
1986年 | 188篇 |
1985年 | 153篇 |
1984年 | 104篇 |
1983年 | 107篇 |
1982年 | 64篇 |
1981年 | 49篇 |
1980年 | 31篇 |
1979年 | 21篇 |
1977年 | 20篇 |
1976年 | 22篇 |
1975年 | 23篇 |
1972年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
A graphic sequence π =(d1, d2,..., dn) is said to be forcibly k-edge-connected if every realization of π is k-edge-connected. In this paper, we obtain a new sufficient degree condition for π to be forcibly k-edgeconnected. We also show that this new sufficient degree condition implies a strongest monotone degree condition for π to be forcibly 2-edge-connected and a conjecture about a strongest monotone degree condition for π to be forcibly 3-edge-connected due to... 相似文献
12.
The molecular geometries and dissociation energies of AnO (An = Bk–Lr) molecules were first obtained at thecoupled-cluster single-, double-, and perturbative triple-excitations [CCSD(T)] level of theory. Four hybrid functionals,B3LYP, M06-2X, TPSSh, and PBE0, were also employed in the calculations for the sake of comparison. In comparison ofthe CCSD(T) results, B3LYP, TPSSh, and PBE0 functionals can obtain more appropriate results than M06-2X and MP2.The analyses on molecular orbitals show that the 7s, 6d, and 5f atomic orbitals of actinide (An) atoms participate in thebonding of An–O bonds. The partial covalent nature between An and O atoms is revealed by QTAIM analyses. 相似文献
13.
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
14.
Xu Mengtao Li Changyou Sun Yang Yang Tianzhi Zhang Hongzhuang Liu Zhendong Liu Haiyang Li Zhenyuan Zhang Yimin 《Nonlinear dynamics》2021,105(4):3061-3092
Nonlinear Dynamics - Investigation of the dynamic characteristics of linear guideway is essential for enhancing structural performance of machine tools. However, few mechanical models are... 相似文献
15.
Journal of Visualization - The increasing availability of spatiotemporal data provides unprecedented opportunities for understanding the structure of an urban area in terms of people’s... 相似文献
16.
Mathematical Programming - In the general equilibrium with incomplete asset markets (GEI) model, the excess demand functions are typically not continuous at the prices for which the assets have... 相似文献
17.
International Journal of Theoretical Physics - The Majorana representation, which provides an intuitive way to represent the quantum state by stars on the Bloch sphere, has drawn considerable... 相似文献
18.
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
19.
20.