全文获取类型
收费全文 | 354712篇 |
免费 | 6050篇 |
国内免费 | 1163篇 |
专业分类
化学 | 197404篇 |
晶体学 | 4632篇 |
力学 | 14308篇 |
综合类 | 7篇 |
数学 | 43324篇 |
物理学 | 102250篇 |
出版年
2021年 | 2241篇 |
2020年 | 2604篇 |
2019年 | 2586篇 |
2018年 | 2874篇 |
2017年 | 2614篇 |
2016年 | 5222篇 |
2015年 | 4483篇 |
2014年 | 5671篇 |
2013年 | 16483篇 |
2012年 | 13649篇 |
2011年 | 16389篇 |
2010年 | 10140篇 |
2009年 | 9744篇 |
2008年 | 14858篇 |
2007年 | 15065篇 |
2006年 | 14390篇 |
2005年 | 13289篇 |
2004年 | 11846篇 |
2003年 | 10297篇 |
2002年 | 9944篇 |
2001年 | 10724篇 |
2000年 | 8261篇 |
1999年 | 6506篇 |
1998年 | 5213篇 |
1997年 | 5003篇 |
1996年 | 5169篇 |
1995年 | 4608篇 |
1994年 | 4404篇 |
1993年 | 4249篇 |
1992年 | 4746篇 |
1991年 | 4550篇 |
1990年 | 4265篇 |
1989年 | 4069篇 |
1988年 | 4323篇 |
1987年 | 3997篇 |
1986年 | 3829篇 |
1985年 | 5590篇 |
1984年 | 5657篇 |
1983年 | 4559篇 |
1982年 | 4994篇 |
1981年 | 5017篇 |
1980年 | 4741篇 |
1979年 | 4843篇 |
1978年 | 4855篇 |
1977年 | 4789篇 |
1976年 | 4791篇 |
1975年 | 4682篇 |
1974年 | 4543篇 |
1973年 | 4695篇 |
1972年 | 2657篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
Inside Cover: Ru‐Catalysed CH Arylation of Indoles and Pyrroles with Boronic Acids: Scope and Mechanistic Studies (Chem. Eur. J. 14/2015)
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
43.
Cover Picture: Coordination Chemistry of N‐Heterocyclic Nitrenium‐Based Ligands (Chem. Eur. J. 19/2015)
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
44.
Thalia Tsiaka Panagiotis Zoumpoulakis Vassilia J. Sinanoglou Constantinos Makris Georgios A. Heropoulos Antony C. Calokerinos 《Analytica chimica acta》2015
High-energy assisted extraction techniques, like ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE), are widely applied over the last years for the recovery of bioactive compounds such as carotenoids, antioxidants and phenols from foods, animals and herbal natural sources. Especially for the case of xanthophylls, the main carotenoid group of crustaceans, they can be extracted in a rapid and quantitative way with the use of UAE and MAE. 相似文献
45.
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
46.
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
47.
Kounta Moussa Dawson Nathan J. 《Methodology and Computing in Applied Probability》2021,23(3):1155-1172
Methodology and Computing in Applied Probability - The problem of optimally controlling one-dimensional diffusion processes until they enter a given stopping set is extended to include Markov... 相似文献
48.
49.
Transport in Porous Media - The theme of coupling problems for adsorption, absorption and thermochemical transport in porous media is very important for engineering applications. Based on the... 相似文献
50.
It is known that under resonance conditions, a group of strongly interacting bosonic atoms, trapped in a double-well potential, mimics a single particle, performing Rabi oscillations between the wells. By implication, all atoms need to tunnel at roughly the same time, even though the Bose–Hubbard Hamiltonian accounts only for one-atom-at-a-time transfers. The mechanism of this collective behavior is analyzed, the Rabi frequencies in the process are evaluated, and the limitation of this simple picture is discussed. In particular, it is shown that the small rapid oscillations superimposed on the slow Rabi cycle result from splitting the transferred cluster at the sudden onset of tunnelling, and disappear if tunnelling is turned on gradually. 相似文献