全文获取类型
收费全文 | 34798篇 |
免费 | 4835篇 |
国内免费 | 3788篇 |
专业分类
化学 | 24401篇 |
晶体学 | 342篇 |
力学 | 2259篇 |
综合类 | 347篇 |
数学 | 3799篇 |
物理学 | 12273篇 |
出版年
2024年 | 121篇 |
2023年 | 672篇 |
2022年 | 1060篇 |
2021年 | 1183篇 |
2020年 | 1290篇 |
2019年 | 1278篇 |
2018年 | 1066篇 |
2017年 | 985篇 |
2016年 | 1504篇 |
2015年 | 1507篇 |
2014年 | 1797篇 |
2013年 | 2423篇 |
2012年 | 3023篇 |
2011年 | 3091篇 |
2010年 | 1978篇 |
2009年 | 1942篇 |
2008年 | 2090篇 |
2007年 | 1960篇 |
2006年 | 1760篇 |
2005年 | 1481篇 |
2004年 | 1116篇 |
2003年 | 951篇 |
2002年 | 979篇 |
2001年 | 763篇 |
2000年 | 707篇 |
1999年 | 779篇 |
1998年 | 679篇 |
1997年 | 651篇 |
1996年 | 703篇 |
1995年 | 558篇 |
1994年 | 521篇 |
1993年 | 433篇 |
1992年 | 422篇 |
1991年 | 373篇 |
1990年 | 279篇 |
1989年 | 222篇 |
1988年 | 174篇 |
1987年 | 147篇 |
1986年 | 137篇 |
1985年 | 130篇 |
1984年 | 95篇 |
1983年 | 70篇 |
1982年 | 46篇 |
1981年 | 40篇 |
1980年 | 20篇 |
1978年 | 19篇 |
1977年 | 23篇 |
1976年 | 20篇 |
1975年 | 28篇 |
1974年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
151.
152.
Chunxia Miao Shihan Qi Kang Liang Yanli Qi Junda Huang Mingguang Wu Hongshun Zhao Jiandong Liu Yurong Ren Jianmin Ma 《Journal of Energy Chemistry》2021,(12):566-573
Lithium metal batteries have obtained increasing interest due to their high specific capacity.Nonetheless,the growth of lithium dendrites brings safety risks to... 相似文献
153.
Jinkun Sun Yingjian Liu Jiayi Huang Jiatian Li Mengmeng Chen Xiaoyu Hu Yatao Liu Run Wang Yanan Shen Jingjing Li Xuecheng Chen Dong Qian Baigang An Zunfeng Liu 《Journal of Energy Chemistry》2021,(12):594-603
Increasing mechanical flexibility without sacrificing electrochemical performance of the electrode mate-rial is highly desired in the design of flexible electro... 相似文献
154.
A highly efficient and environmental-benign oxidation by dioxygen (or air) as the sole oxidant was first applied for the conversion of 2-imidazoline-5-carboxylic derivatives to imidazole-5-carboxylic derivatives in very good and excellent yields. The substituent effect on 2-imidazoline ring was investigated. This protocol was also suitable for the synthesis of 2-imidazoles in relatively large scale. 相似文献
155.
Fanbo SongJing Zhang Quanbin CuiTing Wang Wenbin ChenLuyuan Li Zhen Xi 《Tetrahedron letters》2012,53(9):1102-1104
Inositol phosphates regulate important biological functions in intracellular signal transduction events. Phosphonates, because of the stability towards the action of phosphatases, were extensively used to replace phosphates. We herein reported the synthesis of inositol phosphonate analogues using myo-inositol as the starting material, and found that two of phosphonate analogues exhibited relative good cytotoxic activity against non-small cell lung cancer (NSCLC) cell line A549. 相似文献
156.
Polystyrene-bound diethanolamine based ionic liquids (PS-DHEEAB and PS-THEAB) were synthesized and applied for the chemical fixation of CO2 into cyclic carbonates without any additional co-catalyst and solvent. The effect of the catalysts with different number of hydroxyl group in the cation of the IL on the reaction was systematically investigated. Highest activity and selectivity were achieved in the presence of polystyrene supported diethanolamine ethyl bromide (PS-DHEEAB) in comparison with other catalysts employed. The catalyst was tough in stability and also found to be extended to a variety of terminal epoxides and aziridines. The relationship between high catalytic reactivity and the –OH functional groups was proposed. 相似文献
157.
158.
159.
Molecular dynamics simulations of solid state recrystallization and grain growth in iron nanoparticles containing 1436 atoms were carried out. During the period of relaxation of supercooled liquid drops and during thermal annealing of the solids they froze to, changes in disorder were followed by monitoring changes in energy and the migration of grain boundaries. All 27 polycrystalline nanoparticles, which were generated with different grain boundaries, were observed to recystallize into single crystals during annealing. Larger grains consumed the smaller ones. In particular, two sets of solid particles, designated as A and B, each with two grains, were treated to generate 18 members of each set with different thermal histories. This provided small ensembles (of 18 members each) from which rates at which the larger grain engulfed the smaller one, could be determined. The rate was higher, the smaller the degree of misorientation between the grains, a result contrary to the general rule based on published experiments, but the reason was clear. Crystal A, which happened to have a somewhat lower angle of misorientation, also had a higher population of defects, as confirmed by its higher energy. Accordingly, its driving force to recrystallize was greater. Although the mechanism of recrystallization is commonly called nucleation, our results, which probe the system on an atomic scale, were not able to identify nuclei unequivocally. By contrast, our technique can and does reveal nuclei in the freezing of liquids and in transformations from one solid phase to another. An alternative rationale for a nucleation-like process in our results is proposed. 相似文献
160.