全文获取类型
收费全文 | 76607篇 |
免费 | 13383篇 |
国内免费 | 8221篇 |
专业分类
化学 | 54051篇 |
晶体学 | 736篇 |
力学 | 4899篇 |
综合类 | 400篇 |
数学 | 8905篇 |
物理学 | 29220篇 |
出版年
2024年 | 78篇 |
2023年 | 1592篇 |
2022年 | 1698篇 |
2021年 | 2533篇 |
2020年 | 3245篇 |
2019年 | 3039篇 |
2018年 | 2629篇 |
2017年 | 2455篇 |
2016年 | 3725篇 |
2015年 | 3614篇 |
2014年 | 4301篇 |
2013年 | 5570篇 |
2012年 | 7093篇 |
2011年 | 7309篇 |
2010年 | 4893篇 |
2009年 | 4639篇 |
2008年 | 5074篇 |
2007年 | 4512篇 |
2006年 | 4150篇 |
2005年 | 3476篇 |
2004年 | 2705篇 |
2003年 | 2173篇 |
2002年 | 2061篇 |
2001年 | 1621篇 |
2000年 | 1455篇 |
1999年 | 1624篇 |
1998年 | 1366篇 |
1997年 | 1329篇 |
1996年 | 1300篇 |
1995年 | 1083篇 |
1994年 | 947篇 |
1993年 | 792篇 |
1992年 | 703篇 |
1991年 | 614篇 |
1990年 | 524篇 |
1989年 | 396篇 |
1988年 | 352篇 |
1987年 | 289篇 |
1986年 | 264篇 |
1985年 | 219篇 |
1984年 | 149篇 |
1983年 | 109篇 |
1982年 | 86篇 |
1981年 | 71篇 |
1980年 | 69篇 |
1979年 | 35篇 |
1978年 | 34篇 |
1977年 | 41篇 |
1976年 | 31篇 |
1973年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
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
92.
Nonlinear Dynamics - This paper investigates a Hopfield neural network under the simulation of external electromagnetic radiation and dual bias currents, in which the fluctuation of magnetic flux... 相似文献
93.
Asymmetric mode transformation in waveguide is of great significance for on-chip integrated devices with one-way effect, while it is challenging to achieve asymmetric nonlinear-mode-conversion (NMC) due to the limitations imposed by phase-matching. In this work, we theoretically proposed a new scheme for realizing asymmetric NMC by combining frequency-doubling process and periodic PT symmetric modulation in an optical waveguide. By engineering the one-way momentum from PT symmetric modulation, we have demonstrated the unidirectional conversion from pump to second harmonic with desired guided modes. Our findings offer new opportunities for manipulating nonlinear optical fields with PT symmetry, which could further boost more exploration on on-chip nonlinear devices assisted by non-Hermitian optics. 相似文献
94.
Nonlinear Dynamics - This paper studies reverse space and/or time nonlocal Fokas–Lenells (FL) equation, which describes the propagation of nonlinear light pulses in monomode optical fibers... 相似文献
95.
Liu Chongyang Gong Zhaohua Teo Kok Lay Wang Song 《Journal of Optimization Theory and Applications》2022,193(1-3):856-876
Journal of Optimization Theory and Applications - This paper considers an optimal control problem governed by nonlinear fractional-order systems with multiple time-varying delays and subject to... 相似文献
96.
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
97.
Yan-Cen Liu Dr. Shu Peng Lora Angelova Prof. Dr. Werner M. Nau Dr. Andreas Hennig 《ChemistryOpen》2019,8(11):1350-1354
The combination of the macrocyclic hosts p-sulfonatocalix[4]arene and cucurbit[7]uril with the fluorescent dyes lucigenin and berberine affords two label-free enzyme assays for the detection of kinase and phosphatase activity by fluorescence monitoring. In contrast to established assays, no substrate labeling is required. Since phosphorylation is one of the most important regulatory mechanisms in biological signal transduction, the assays should be useful for identification of inhibitors and activators in high-throughput screening (HTS) format for drug discovery. 相似文献
98.
Wu Peng Wang Yun Li Yang Hu Xuewen Xiu Taoyuan Yuan Dingzhong Liu Yan Wu Zhenyu Liu Zhirong 《Journal of Radioanalytical and Nuclear Chemistry》2019,322(2):553-559
Journal of Radioanalytical and Nuclear Chemistry - In order to reduce the potential toxicity to the environment after treatment of radioactive waste water, an eco-friendly graphene oxide... 相似文献
99.
Peng-Yan Gui Xiao-Hui Yan Wen-Juan Yuan Yuan-Liang Ma Xiao Ding Shuai Liu 《Natural product research》2019,33(19):2830-2836
A new A, D-seco limonoid, named 12-acetyloxyperforatin (1), along with three known ones, were isolated from the leaves of Harrisonia perforata. Their structures were elucidated on the basis of spectroscopic analysis, including extensive NMR techniques and computational modelling. These compounds showed no inhibitory activity against the 11β-HSD1 enzyme. 相似文献
100.
Aysun apc Mlanie M. Lorion Hui Wang Nina Simon Maria Leidenberger Mariana C. BorgesSilva Diogo R. M. Moreira Yongping Zhu Yuqing Meng Jia Yun Chen Yew Mun Lee Oliver Friedrich Barbara Kappes Jigang Wang Lutz Ackermann Svetlana B. Tsogoeva 《Angewandte Chemie (International ed. in English)》2019,58(37):13161-13161