全文获取类型
收费全文 | 48062篇 |
免费 | 7713篇 |
国内免费 | 6060篇 |
专业分类
化学 | 35267篇 |
晶体学 | 619篇 |
力学 | 2537篇 |
综合类 | 400篇 |
数学 | 4906篇 |
物理学 | 18106篇 |
出版年
2024年 | 166篇 |
2023年 | 845篇 |
2022年 | 1585篇 |
2021年 | 1792篇 |
2020年 | 1833篇 |
2019年 | 1855篇 |
2018年 | 1582篇 |
2017年 | 1440篇 |
2016年 | 2247篇 |
2015年 | 2239篇 |
2014年 | 2805篇 |
2013年 | 3626篇 |
2012年 | 4235篇 |
2011年 | 4292篇 |
2010年 | 2951篇 |
2009年 | 2844篇 |
2008年 | 3291篇 |
2007年 | 2924篇 |
2006年 | 2741篇 |
2005年 | 2208篇 |
2004年 | 1847篇 |
2003年 | 1558篇 |
2002年 | 1646篇 |
2001年 | 1301篇 |
2000年 | 1021篇 |
1999年 | 1015篇 |
1998年 | 771篇 |
1997年 | 771篇 |
1996年 | 712篇 |
1995年 | 622篇 |
1994年 | 520篇 |
1993年 | 447篇 |
1992年 | 430篇 |
1991年 | 334篇 |
1990年 | 302篇 |
1989年 | 234篇 |
1988年 | 140篇 |
1987年 | 130篇 |
1986年 | 141篇 |
1985年 | 108篇 |
1984年 | 63篇 |
1983年 | 61篇 |
1982年 | 40篇 |
1981年 | 36篇 |
1980年 | 17篇 |
1979年 | 7篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1976年 | 9篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Tomomi Ishikawa LuChang Jin Huey-Wen Lin Andreas Sch?fer Yi-Bo Yang Jian-Hui Zhang Yong Zhao 《中国科学:物理学 力学 天文学(英文版)》2019,(9)
正Recent years have witnessed rapid progress in calculating parton distribution functions (PDFs), rather than just their moments, from lattice QCD [1-9]. The most remarkable aspect of such calculations is that one can connect appropriately chosen Euclidean correlation functions calculable on the lattice to PDFs through a perturbative matching relation. This can be understood in the framework of the large-momentum 相似文献
992.
YongGuang Tu GuoNing Xu XiaoYu Yang YiFei Zhang ZhaoJie Li Rui Su DeYing Luo WenQiang Yang Ying Miao Rong Cai LuHua Jiang XiaoWei Du YanChu Yang QianShi Liu Yang Gao Shuai Zhao Wei Huang QiHuang Gong Rui Zhu 《中国科学:物理学 力学 天文学(英文版)》2019,(7)
<正>The metal halide perovskite materials demonstrate outstanding performance in photovoltaics because of their excellent optoelectronic properties [1-7]. The perovskite solar cells (PSCs) exhibiting outstanding efficiency [8,9], high power-per-weight [10], and excellent radiation resistance[11-13] are considered to be promising for developing the new-generation energy technology for space application.However, the extreme space environment would impose 相似文献
993.
Zhang Yi Wang Xiaohui Feng Wei Zhen Yichao Zhao Peiyao Li Longtu Cai Ziming 《Journal of Solid State Electrochemistry》2019,23(3):749-758
Journal of Solid State Electrochemistry - For all-solid-state lithium-ion batteries, several disadvantages such as low ionic conductivity and poor interfacial stability have been concerned.... 相似文献
994.
Li Xuetian Shao Zhongbao Liu Kuiren Zhao Qing Liu Guangfu Xu Binshi 《Journal of Solid State Electrochemistry》2019,23(2):465-473
Journal of Solid State Electrochemistry - Li1-xNbxFePO4/C has been prepared by wet mechanical stirring–assisted high-temperature ball milling route. Wet mechanical stirring was considered to... 相似文献
995.
996.
997.
High-order curvilinear mesh generation technique based on an improved radius basic function approach
A high-order curvilinear hybrid mesh generation technique is developed for high-order numerical method (eg, discontinuous Galerkin method) applications to improve the accuracy for problems with curve boundary. The grid generation technique is based on an improved radius basic function (RBF) approach by which the straight-edge mesh is converted into high-order curve mesh. Firstly, an initial straight-edge mesh is prepared by traditional grid generation software. Then, high-order interpolation points are inserted into the mesh entities such as edges, faces, and cells according to the final demand of mesh order. To preserve the original geometry, the inserted points on solid wall are then projected onto the CAD model using an open source tool “Open Cascade.” Finally, other inserted points in the field near the solid wall are moved to appropriate positions by the improved RBF approach to avoid tangled cells. If we use the original RBF approach, then the inserted points on the edge and face entities normal to the solid boundary in the region of boundary layer will move to improper positions. To overcome this problem, a weighting based on the local grid aspect ratio between normal direction and tangential direction is introduced into the baseline RBF approach. Three typical configurations are tested to validate the mesh generator. Meanwhile, a third-order solution of subsonic flow over an analytical 3D body of revolution in the second International Workshop on High-Order CFD Methods is supplied by a discontinuous Galerkin solver. These numerical tests demonstrate the potential capability of present technique for high-order simulations of complex geometries. 相似文献
998.
Nonlinear Dynamics - With the increasing demand for aquatic products all over the world, exploring the interactions between inshore and offshore fisheries is one of the meaningful issues to help... 相似文献
999.
Two stable heterometal‐organic frameworks, {Na[LnCo(DATP)2(Ac)(H2O)](NO3)?DMA?11 H2O}n (Ln=Er( 1 ) and Yb( 2 )), have been prepared with H2DATP (4′‐(3,5‐dicarboxyphenyl)‐2,2′:6′,2′′′‐terpyridine) as organic building block. These two isostructural compounds featuring two‐dimensional layer architectures possess outstanding thermal stabilities and excellent chemical stabilities in common organic solvents and different acid/base solutions with pH range changing from 1 to 13. Moreover, compounds 1 and 2 serving as heterogeneous catalysts can efficiently catalyse the CO2 fixation reaction with various aziridines to result in corresponding oxazolidinones at 70 °C. Importantly, a good recyclable performance of 1 for at least 10 cycles is observed based on the experimental results, which are further confirmed by PXRD, TGA and ICP analyses. 相似文献
1000.
Flexible control of building blocks of photonic crystals enables achieving desirable band structures. Exploration of photonic band extrema has brought many fantastic features to design artificial optical materials, such as Brillouin‐zone‐corner extrema for valley photonic materials and zone‐center extremum for zero‐index metamaterials. However, two such kinds of extrema are always found independently in different photonic crystals. In this work, a kind of valley photonic crystals possessing both zone‐center and zone‐corner band extrema almost at the same frequency is proposed. Inspired by antennas theory, a three‐antenna array (TAA) source is devoted to individually manipulate each extremum. The correlation coefficient is given to determine the coupling efficiency between the TAA source and extrema eigenmodes. By using a source with a high correlation coefficient, these extrema bulk states are selectively excited consistent with their eigenfields. Furthermore, three control cases are shown that multiple extrema points are simultaneously excited, in order to confirm the validity of the correlation coefficient. Finally, a potential application of a beam‐steering device is proposed through selective excitation of ternary extrema. This work develops binary valley states into ternary mix states, rendering more degrees of freedom for on‐chip optical information transport, particularly for beam steering and mode division multiplexing. 相似文献