全文获取类型
收费全文 | 371237篇 |
免费 | 5388篇 |
国内免费 | 1136篇 |
专业分类
化学 | 192092篇 |
晶体学 | 4905篇 |
力学 | 17001篇 |
综合类 | 22篇 |
数学 | 45647篇 |
物理学 | 118094篇 |
出版年
2021年 | 3591篇 |
2020年 | 4011篇 |
2019年 | 4414篇 |
2018年 | 6150篇 |
2017年 | 6199篇 |
2016年 | 8789篇 |
2015年 | 5441篇 |
2014年 | 8310篇 |
2013年 | 18571篇 |
2012年 | 15417篇 |
2011年 | 18006篇 |
2010年 | 12864篇 |
2009年 | 12444篇 |
2008年 | 15851篇 |
2007年 | 15823篇 |
2006年 | 14455篇 |
2005年 | 12808篇 |
2004年 | 11757篇 |
2003年 | 10248篇 |
2002年 | 10053篇 |
2001年 | 11153篇 |
2000年 | 8307篇 |
1999年 | 6452篇 |
1998年 | 5328篇 |
1997年 | 5133篇 |
1996年 | 4887篇 |
1995年 | 4129篇 |
1994年 | 4139篇 |
1993年 | 4019篇 |
1992年 | 4435篇 |
1991年 | 4579篇 |
1990年 | 4264篇 |
1989年 | 4163篇 |
1988年 | 3914篇 |
1987年 | 4057篇 |
1986年 | 3790篇 |
1985年 | 4874篇 |
1984年 | 4932篇 |
1983年 | 4034篇 |
1982年 | 4204篇 |
1981年 | 3918篇 |
1980年 | 3830篇 |
1979年 | 4119篇 |
1978年 | 4094篇 |
1977年 | 4061篇 |
1976年 | 4097篇 |
1975年 | 3837篇 |
1974年 | 3813篇 |
1973年 | 3836篇 |
1972年 | 2670篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
121.
Technical Physics - A need to study the structure of the NMR signals detected with the aid of the modulation method is substantiated. Specific features of the detection of the NMR signals using the... 相似文献
122.
Technical Physics - The temperature dependence of the conductivity of heat-treated polyvinyl chloride films containing conjugated double carbon–carbon bonds in the chain of its macromolecules... 相似文献
123.
124.
125.
Echabaane M. Hfaiedh S. Smiri B. Saidi F. Dridi C. 《Journal of Solid State Electrochemistry》2021,25(6):1797-1806
Journal of Solid State Electrochemistry - The fast and sensitive detection of copper ions would be essential for water monitoring. Herein, we report a novel development of an impedimetric sensor... 相似文献
126.
JETP Letters - An Erratum to this paper has been published: https://doi.org/10.1134/S0021364022400028 相似文献
127.
Journal of Experimental and Theoretical Physics - The nature of the training effect in exchange-biased compounds is studied. This effect consists in a decrease in the exchange bias field (HEB)... 相似文献
128.
Dapeng Liu Binod R. Giri Milán Szőri Béla Viskolcz Et-touhami Es-sebbar Aamir Farooq 《Proceedings of the Combustion Institute》2021,38(1):967-976
NOx mitigation is a central focus of combustion technologies with increasingly stringent emission regulations. NOx can also enhance the autoignition of hydrocarbon fuels and can promote soot oxidation. The reaction between allyl radical (C3H5) and NOx plays an important role in the oxidation kinetics of propene. In this work, we measured the absolute rate coefficients for the redox reaction between C3H5 and NOx over the temperature range of 1000–1252 K and pressure range of 1.5–5.0 bar using a shock tube and UV laser absorption technique. We produced C3H5 by shock heating of C3H5I behind reflected shock waves. Using a Ti:Sapphire laser system with frequency quadrupling, we monitored the kinetics of C3H5 at 220 nm. Unlike low-temperature chemistry, the two target reactions, C3H5 + NO → products (R1) and C3H5 + NO2 → products (R2), exhibited a strong positive temperature dependence for this radical-radical type reaction. However, these reactions did not show any pressure dependence over the pressure range of 1.5–5.0 bar, indicating that the measured rate coefficients are close to the high-pressure limit. The measured values of the rate coefficients resulted in the following Arrhenius expressions (in unit of cm3/molecule/s):To our knowledge, these are the first high-temperature measurements of allyl + NOx reactions. The reported data will be highly useful in understanding the interaction of NOx with resonantly stabilized radicals as well as the mutual sensitization effect of NOx on hydrocarbon fuels. 相似文献
129.
Algebras and Representation Theory - We introduce and study the category of twisted modules over a triangular differential graded bocs. We show that in this category idempotents split, that it... 相似文献
130.
Ben Jadi S. El Guerraf A. Bazzaoui E.A. Wang R. Martins J.I. Bazzaoui M. 《Journal of Solid State Electrochemistry》2019,23(8):2423-2433
Journal of Solid State Electrochemistry - Due to their distinctive chemical, electronic, and environmental properties, polypyrrole is used as a blocking barrier for methanol leakage in direct... 相似文献