全文获取类型
收费全文 | 23080篇 |
免费 | 3337篇 |
国内免费 | 2459篇 |
专业分类
化学 | 16227篇 |
晶体学 | 276篇 |
力学 | 1359篇 |
综合类 | 191篇 |
数学 | 2325篇 |
物理学 | 8498篇 |
出版年
2024年 | 67篇 |
2023年 | 429篇 |
2022年 | 749篇 |
2021年 | 851篇 |
2020年 | 860篇 |
2019年 | 838篇 |
2018年 | 718篇 |
2017年 | 742篇 |
2016年 | 1020篇 |
2015年 | 1043篇 |
2014年 | 1182篇 |
2013年 | 1619篇 |
2012年 | 1875篇 |
2011年 | 1996篇 |
2010年 | 1306篇 |
2009年 | 1271篇 |
2008年 | 1476篇 |
2007年 | 1357篇 |
2006年 | 1221篇 |
2005年 | 978篇 |
2004年 | 784篇 |
2003年 | 660篇 |
2002年 | 633篇 |
2001年 | 462篇 |
2000年 | 455篇 |
1999年 | 483篇 |
1998年 | 424篇 |
1997年 | 425篇 |
1996年 | 465篇 |
1995年 | 366篇 |
1994年 | 381篇 |
1993年 | 273篇 |
1992年 | 258篇 |
1991年 | 233篇 |
1990年 | 165篇 |
1989年 | 130篇 |
1988年 | 119篇 |
1987年 | 97篇 |
1986年 | 95篇 |
1985年 | 86篇 |
1984年 | 59篇 |
1983年 | 49篇 |
1982年 | 38篇 |
1981年 | 28篇 |
1980年 | 31篇 |
1979年 | 19篇 |
1978年 | 10篇 |
1977年 | 8篇 |
1975年 | 7篇 |
1973年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
LetN be a sufficiently large even integer and
相似文献
83.
84.
85.
介绍了用会聚偏振光测定双轴热拉伸定向有机玻璃板双折射值的原理和实验方法,并提出了对Kramer计算公式的简化和改进。测定了双折射值与拉伸度、拉伸温度的关系并分析了干涉图。 相似文献
86.
87.
A method is proposed to calculate molar conductivity based on mode coupling theory in which the ion transference number is introduced into the theory. The molar conductivities of LiPF6, LiClO4, LiBF4, LiAsF6 in PC (propylene carbonate) are calculated based on this method. The results fit well to the literature data. This presents a potential way to calculate the conductivities of Li-ion battery electrolytes. 相似文献
88.
89.
There have been remarkable progresses in manipulating heterogeneous catalysts' nanostructures in the past decade. The concept of single atom alloy (SAA) was firstly proposed in 2012 when researchers successfully stabilized single Pd atoms on the Cu(111) surface. However, earlier work in 2009, which focused on replacing one Au atom with a Pd atom in thiolate protected Au25 nanoclusters, could also be considered as the pioneer work of single atom alloy. Both kinds of single atom alloys exhibited the potential of maximum utilization of scarce elements and attractive catalytic performances. The well‐defined structures of SAA catalysts make accurate modeling possible, which further realizes the rational design of single atom alloy catalysts. In this review, we summarize the research trajectory of single atom alloys as well as recent achievements in this field. We also introduce several commonly adopted characterization methods for SAA catalysts such as scanning tunneling microscopy (STM), temperature programmed reaction (TPR), extended X‐ray absorption fine structure (EXAFS) spectra, matrix assisted laser desorption/ionization mass spectrum (MALDI‐MS) and differential pulse voltammetry (DPV). Through discussing recent progresses in SAA catalysts, we propose that future researches in this filed should be focused on exploring new kinds of metal nanocrystals and controlling the nanostructure of SAA even more precisely. 相似文献
90.
TheA
1
–X
1
+ system of SnO is studied by laser- induced fluorescence excitation spectroscopy using isotopically enriched tin Sn116. The rotational structure analysis has been carried out for 6-0, 5-0, 2-0 bands. All these spectra were well resolved only with few perturbed lines in 2-0 band. Rotational constantsB
2,B
5,B
6 and henceB
e
,
e
e
have been obtained for the Sn116O molecule. An extension of perturbation study on 4-0 band has been made showing the maximum perturbation occurs at different J values for different isotopes. 相似文献
|