全文获取类型
收费全文 | 170333篇 |
免费 | 1867篇 |
国内免费 | 505篇 |
专业分类
化学 | 87951篇 |
晶体学 | 2282篇 |
力学 | 7147篇 |
综合类 | 3篇 |
数学 | 19549篇 |
物理学 | 55773篇 |
出版年
2020年 | 1436篇 |
2019年 | 1566篇 |
2018年 | 1996篇 |
2017年 | 2079篇 |
2016年 | 3219篇 |
2015年 | 1932篇 |
2014年 | 3167篇 |
2013年 | 7738篇 |
2012年 | 5831篇 |
2011年 | 6968篇 |
2010年 | 5078篇 |
2009年 | 5071篇 |
2008年 | 6613篇 |
2007年 | 6512篇 |
2006年 | 6166篇 |
2005年 | 5582篇 |
2004年 | 5172篇 |
2003年 | 4655篇 |
2002年 | 4238篇 |
2001年 | 5091篇 |
2000年 | 3705篇 |
1999年 | 2757篇 |
1998年 | 2304篇 |
1997年 | 2269篇 |
1996年 | 2097篇 |
1995年 | 2081篇 |
1994年 | 2092篇 |
1993年 | 1969篇 |
1992年 | 2264篇 |
1991年 | 2202篇 |
1990年 | 2149篇 |
1989年 | 2081篇 |
1988年 | 2084篇 |
1987年 | 2092篇 |
1986年 | 1984篇 |
1985年 | 2615篇 |
1984年 | 2653篇 |
1983年 | 2340篇 |
1982年 | 2475篇 |
1981年 | 2271篇 |
1980年 | 2253篇 |
1979年 | 2415篇 |
1978年 | 2452篇 |
1977年 | 2387篇 |
1976年 | 2437篇 |
1975年 | 2361篇 |
1974年 | 2322篇 |
1973年 | 2501篇 |
1972年 | 1620篇 |
1971年 | 1336篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Zlámalová M. Pitňa Lásková B. Vinarčíková M. Zukalová M. Kavan L. 《Journal of Solid State Electrochemistry》2022,26(3):639-647
Journal of Solid State Electrochemistry - The addition of nanocrystalline titanium dioxide (P90) to a cathode of Li/S cell enhances its voltammetric charge capacity by 19%, from which only a small... 相似文献
52.
53.
Chebodaeva V. V. Sedelnikova M. B. Bakina O. V. Sharkeev Yu. P. 《Russian Physics Journal》2021,64(8):1435-1442
Russian Physics Journal - A method for modification of calcium-phosphate coatings, formed by microarc oxidation, with Fe–Cu nanocomposite bicomponent particles is proposed. The effect of... 相似文献
54.
Transport in Porous Media - There is a recent surge in research activities on modeling the flow of fluids in porous media with complex pore-networks. A prominent mathematical model, which describes... 相似文献
55.
Romanova O. B. Kretinin V. V. Aplesnin S. S. Sitnikov M. N. Udod L. V. Yanushkevich K. I. 《Physics of the Solid State》2021,63(6):897-903
Physics of the Solid State - Semiconductor BiFe0.95Co0.05O3 thin-film compounds have been synthesized by a burst technique. The film surface morphology and the effect of electronic doping via... 相似文献
56.
Eltanany B. M. El-Hadi H. R. Abd Zaazaa H. E. Eissa M. S. 《Journal of Applied Spectroscopy》2021,88(5):1081-1087
Journal of Applied Spectroscopy - Chloramphenicol (CHL), dexamethasone sodium phosphate (DSP), and tetrahydrozoline HCl (THZ) are co-formulated for conjunctivitis treatment. The ternary mixture... 相似文献
57.
Burachik Regina S. Dao Minh N. Lindstrom Scott B. 《Journal of Optimization Theory and Applications》2021,189(3):744-771
Journal of Optimization Theory and Applications - We study the implications of a well-known metric inequality condition on sets to the applicability of standard necessary optimality conditions for... 相似文献
58.
Crystallography Reports - A novel 3D metal coordination polymer, {[Na4(µ2-H2O)(DMF)2(BCT)2]?DMF}n (I) (DMF = N,N-dimethylformamide, H2BCT =... 相似文献
59.
Fluid Dynamics - To predict the boundary layer transition on swept wings, experimental and numerical researches were conducted to obtained the accurate boundary layer transition front and to... 相似文献
60.
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