全文获取类型
收费全文 | 12273篇 |
免费 | 2176篇 |
国内免费 | 1865篇 |
专业分类
化学 | 9358篇 |
晶体学 | 100篇 |
力学 | 725篇 |
综合类 | 114篇 |
数学 | 1521篇 |
物理学 | 4496篇 |
出版年
2024年 | 34篇 |
2023年 | 237篇 |
2022年 | 330篇 |
2021年 | 341篇 |
2020年 | 441篇 |
2019年 | 505篇 |
2018年 | 411篇 |
2017年 | 361篇 |
2016年 | 553篇 |
2015年 | 621篇 |
2014年 | 660篇 |
2013年 | 845篇 |
2012年 | 1058篇 |
2011年 | 1075篇 |
2010年 | 802篇 |
2009年 | 722篇 |
2008年 | 837篇 |
2007年 | 763篇 |
2006年 | 722篇 |
2005年 | 651篇 |
2004年 | 587篇 |
2003年 | 491篇 |
2002年 | 527篇 |
2001年 | 374篇 |
2000年 | 300篇 |
1999年 | 337篇 |
1998年 | 230篇 |
1997年 | 221篇 |
1996年 | 198篇 |
1995年 | 172篇 |
1994年 | 141篇 |
1993年 | 99篇 |
1992年 | 93篇 |
1991年 | 108篇 |
1990年 | 97篇 |
1989年 | 75篇 |
1988年 | 58篇 |
1987年 | 37篇 |
1986年 | 52篇 |
1985年 | 47篇 |
1984年 | 23篇 |
1983年 | 17篇 |
1982年 | 18篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1974年 | 3篇 |
1968年 | 3篇 |
1957年 | 3篇 |
1936年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Lijuan Shen Li Li Sheng Lu Xiaohan Zhang Jie Liu Junlin An Guojun Zhang Bo Wu Fei Wang 《中国颗粒学报》2015,(3):10-15
We conducted measurements of black carbon(BC) aerosol in Jiaxing,China during autumn from September 26 to November 30,2013.We investigated temporal and diurnal variations of BC,and its correlations with meteorological parameters and other major pollutants.Results showed that hourly mass concentrations of BC ranged from 0.2 to 22.0 μg/m3,with an average of 5.1 μg/m3.The diurnai variation of BC exhibited a bimodal distribution,with peaks at 07:00 and 18:00.The morning peak was larger than the evening peak.The mass percentages of BC in PM2.5 and PM10 were 7.1%and 4.8%,respectively.The absorption coefficient of BC was calculated to be 44.4 Mm-1,which accounted for 11.1%of the total aerosol extinction.BC was mainly emitted from local sources in southwestern Jiaxing where BC concentrations were generally greater than 11 μg/m3 during the measurement period.Correlation analysis indicated that the main sources of BC were motor vehicle exhaust,and domestic and industrial combustion. 相似文献
2.
3.
4.
Cuixia Cui Yong Gao Dr. Jun Li Chao Yang Meng Liu Prof. Dr. Huile Jin Prof. Dr. Zhenhai Xia Prof. Dr. Liming Dai Prof. Dr. Yong Lei Prof. Dr. Jichang Wang Prof. Dr. Shun Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(20):8002-8007
Although tremendous efforts have been devoted to understanding the origin of boosted charge storage on heteroatom-doped carbons, none of the present studies has shown a whole landscape. Herein, by both experimental evidence and theoretical simulation, it is demonstrated that heteroatom doping not only results in a broadened operating voltage, but also successfully promotes the specific capacitance in aqueous supercapacitors. In particular, the electrolyte cations adsorbed on heteroatom-doped carbon can effectively inhibit hydrogen evolution reaction, a key step of water decomposition during the charging process, which broadens the voltage window of aqueous electrolytes even beyond the thermodynamic limit of water (1.23 V). Furthermore, the reduced adsorption energy of heteroatom-doped carbon consequently leads to more stored cations on the heteroatom-doped carbon surface, thus yielding a boosted charge storage performance. 相似文献
5.
6.
7.
8.
9.
Summary. Let be a square matrix dependent on parameters and , of which we choose as the eigenvalue parameter. Many computational problems are equivalent to finding a point such that has a multiple eigenvalue at . An incomplete decomposition of a matrix dependent on several parameters is proposed. Based on the developed theory two new algorithms are
presented for computing multiple eigenvalues of with geometric multiplicity . A third algorithm is designed for the computation of multiple eigenvalues with geometric multiplicity but which also appears to have local quadratic convergence to semi-simple eigenvalues. Convergence analyses of these methods
are given. Several numerical examples are presented which illustrate the behaviour and applications of our methods.
Received December 19, 1994 / Revised version received January 18, 1996 相似文献
10.
提出用溶胶粒子表面修饰方法,结合溶胶凝胶技术制备无机催化膜.该方法的基本原理是利用合适的金属配合物在胶粒表面的吸附作用,经溶胶凝胶过程,将活性组分结合到无机膜中.实验测定结果表明:(NiEDTA)2-,VO-3,MoO2-4,(Pd(NH3)4)2+,PdCl2-4,PtCl2-6和RhCl3-6可用来修饰AlOOH溶胶.以Pd/γAl2O3催化膜的制备为例,经三次溶胶凝胶过程,可制得无裂缺的厚度为9μm的Pd/γAl2O3催化膜,膜材料的平均孔直径为6nm,Pd被均匀地分布在膜的顶层,其平均粒径为23nm. 相似文献