全文获取类型
收费全文 | 342560篇 |
免费 | 3523篇 |
国内免费 | 979篇 |
专业分类
化学 | 173584篇 |
晶体学 | 5544篇 |
力学 | 15928篇 |
综合类 | 8篇 |
数学 | 39564篇 |
物理学 | 112434篇 |
出版年
2022年 | 2731篇 |
2021年 | 3521篇 |
2020年 | 3756篇 |
2019年 | 4237篇 |
2018年 | 5640篇 |
2017年 | 5845篇 |
2016年 | 7964篇 |
2015年 | 4551篇 |
2014年 | 7668篇 |
2013年 | 16999篇 |
2012年 | 13335篇 |
2011年 | 15808篇 |
2010年 | 11642篇 |
2009年 | 11417篇 |
2008年 | 13836篇 |
2007年 | 13818篇 |
2006年 | 12655篇 |
2005年 | 10952篇 |
2004年 | 10152篇 |
2003年 | 8931篇 |
2002年 | 8881篇 |
2001年 | 10503篇 |
2000年 | 7758篇 |
1999年 | 6034篇 |
1998年 | 5026篇 |
1997年 | 4881篇 |
1996年 | 4549篇 |
1995年 | 3919篇 |
1994年 | 3875篇 |
1993年 | 3773篇 |
1992年 | 4174篇 |
1991年 | 4368篇 |
1990年 | 4149篇 |
1989年 | 4061篇 |
1988年 | 3823篇 |
1987年 | 3953篇 |
1986年 | 3715篇 |
1985年 | 4681篇 |
1984年 | 4728篇 |
1983年 | 3932篇 |
1982年 | 4011篇 |
1981年 | 3726篇 |
1980年 | 3687篇 |
1979年 | 3964篇 |
1978年 | 3939篇 |
1977年 | 3945篇 |
1976年 | 3916篇 |
1975年 | 3702篇 |
1974年 | 3633篇 |
1973年 | 3666篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Experimental data on the effect of thallium and sodium impurities on the lattice heat conductivity of PbTe at room temperature
are reported. Because the lattice of lead chalcogenides is strongly polarized near charged impurities, the effect of impurities
on the lattice heat conductivity depends substantially on their charge state. This property of the material has been used
to determine the charge state of the thallium impurity in PbTe. The results obtained argue for a model of quasi-local thallium-impurity
states which assumes low electron-correlation energy at an impurity center.
Fiz. Tverd. Tela (St. Petersburg) 40, 1206–1208 (July 1998) 相似文献
12.
13.
Open circuit voltage (OCV) measurements in H2O/air concentration cells at T<580 K using Yb-doped SrCeO3 electrolyte indicate that under these conditions, protons are transported through the electrolyte as -ve ions, possibly as
hydroxyl (OH−) ions. The H+ ionic transport, which is generally reported, becomes the dominant mode for H2O/air concentration cells at temperatures greater than 750 K or when H2O/air electrodes are replaced by H2/Ar, and the anomalous OCV sign disappears. The combination of low temperature and the presence of hydrogen and oxygen as
provided by the H2O/air system appears to be necessary for the postulated hydroxyl ion electrode reactions to take place.
In addition to OCV measurements, results from impedance spectroscopy are used to provide evidence in support of the suggested
hydroxyl ion mode of protonic transport under the specified conditions. These findings are directly relevant in the development
of novel humidity sensors in the temperature range 450–580K and is reported in a separate paper in this conference.
Paper presented at the 3rd Euroconference on Solid State Ionics, Teulada, Sardinia, Italy, Sept. 15–22, 1996 相似文献
14.
15.
16.
Myagchenkov V. A. Chichkanov S. V. Proskurina V. E. Myagchenkov A. V. 《Russian Journal of Applied Chemistry》2002,75(9):1485-1488
The Thoms effect observed with water-soluble cationic copolymer of acrylamide was studied in relation to the concentration, molecular weight, and molecular weight polydispersity of the polymeric additive, with its composition and composition polydispersity being constant. 相似文献
17.
18.
A. J. Parsons S. D. J. Inglethorpe D. J. Morgan A. C. Dunham 《Journal of Thermal Analysis and Calorimetry》1997,48(1):49-62
Using a system based on non-dispersive infrared (NDIR) detectors, evolved gas analysis (EGA) was able to identify and quantify the principal volatiles produced by heating powdered samples of UK brick clays. From these results, atmospheric emissions likely to result from brick production can be predicted. In addition, EGA results for extruded brick clay test pieces are significantly different from those of powdered samples. Within an extruded brick clay body, evolved gases are contained within a pore system and evolved gas-solid phase reactions also occur. This EGA study provides further evidence on the nature of firing reactions within brick clay bodies. The qualitative and quantitative influence of heating rate — a key process condition in brick manufacture — on gas release is also outlined.Dedicated to Dr. Robert Mackenzie on the occasion of his 75th birthday 相似文献
19.
20.