全文获取类型
收费全文 | 345343篇 |
免费 | 7120篇 |
国内免费 | 4056篇 |
专业分类
化学 | 173382篇 |
晶体学 | 4469篇 |
力学 | 17921篇 |
综合类 | 335篇 |
数学 | 51918篇 |
物理学 | 108494篇 |
出版年
2021年 | 2379篇 |
2020年 | 2887篇 |
2019年 | 3016篇 |
2018年 | 11757篇 |
2017年 | 12519篇 |
2016年 | 8813篇 |
2015年 | 4446篇 |
2014年 | 5239篇 |
2013年 | 11206篇 |
2012年 | 14488篇 |
2011年 | 23955篇 |
2010年 | 15164篇 |
2009年 | 15093篇 |
2008年 | 20713篇 |
2007年 | 23926篇 |
2006年 | 10302篇 |
2005年 | 15302篇 |
2004年 | 11210篇 |
2003年 | 10219篇 |
2002年 | 8174篇 |
2001年 | 7640篇 |
2000年 | 6136篇 |
1999年 | 4487篇 |
1998年 | 3767篇 |
1997年 | 3693篇 |
1996年 | 3937篇 |
1995年 | 3309篇 |
1994年 | 3354篇 |
1993年 | 3113篇 |
1992年 | 3318篇 |
1991年 | 3342篇 |
1990年 | 3000篇 |
1989年 | 2868篇 |
1988年 | 2801篇 |
1987年 | 2697篇 |
1986年 | 2691篇 |
1985年 | 3493篇 |
1984年 | 3533篇 |
1983年 | 2935篇 |
1982年 | 3161篇 |
1981年 | 2920篇 |
1980年 | 2704篇 |
1979年 | 2885篇 |
1978年 | 3125篇 |
1977年 | 3071篇 |
1976年 | 3128篇 |
1975年 | 2871篇 |
1974年 | 2972篇 |
1973年 | 3051篇 |
1972年 | 2359篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
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
92.
本文基于新的Kronecker型替换,给出两个由黑盒表示的稀疏多项式的新确定性插值算法.令f∈R[x1,……,xn]是一个稀疏黑盒多项式,其次数上界为D.当R是C或者是有限域时,相对于已有算法,新算法具有更好的计算复杂度或者关于D的复杂度更低.特别地,对于一般黑盒模型,D是复杂度中的主要因素,而在所有的确定性算法中,本文的第二个算法的复杂度关于D是最低的. 相似文献
93.
E. V. Shadrina O. N. Malinkina T. G. Khonina A. B. Shipovskaya V. I. Fomina E. Yu. Larchenko N. A. Popova I. G. Zyryanova L. P. Larionov 《Russian Chemical Bulletin》2015,64(7):1633-1639
The biomimetic sol—gel synthesis of silicon—chitosan-containing glycerohydrogels was carried out using silicon tetraglycerolate as a precursor. It was found that chitosan accelerates gel formation in weakly acidic media. In more acidic media, the kinetics of the process changes according to the curve with a maximum, which can be attributed to different mechanisms of silanol condensation before and after the isoelectric point. The investigated silicon—chitosan-containing glycerohydrogels exhibit antibacterial, anti-inflammatory, and wound healing activity. The synthesized hybrid glycerohydrogels are promising materials for biomedical applications. 相似文献
94.
95.
96.
97.
Dorovskikh S. I. Stabnikov P. А. Zelenina L. N. Sysoev S. V. Morozova N. B. 《Russian Journal of General Chemistry》2021,91(10):1977-1983
Russian Journal of General Chemistry - Thermogravimetry, differential scanning calorimetry, and flow methods were used to investigate thermal properties of a series of cobalt(II)... 相似文献
98.
Pu Duan Bo Zhi Luke Coburn Christy L. Haynes Klaus Schmidt-Rohr 《Magnetic resonance in chemistry : MRC》2020,58(11):1130-1138
The composition of fluorescent polymer nanoparticles, commonly referred to as carbon dots, synthesized by microwave-assisted reaction of citric acid and ethylenediamine was investigated by 13C, 13C{1H}, 1H─13C, 13C{14N}, and 15N solid-state nuclear magnetic resonance (NMR) experiments. 13C NMR with spectral editing provided no evidence for significant condensed aromatic or diamondoid carbon phases. 15N NMR showed that the nanoparticle matrix has been polymerized by amide and some imide formation. Five small, resolved 13C NMR peaks, including an unusual ═CH signal at 84 ppm (1H chemical shift of 5.8 ppm) and ═CN2 at 155 ppm, and two distinctive 15N NMR resonances near 80 and 160 ppm proved the presence of 5-oxo-1,2,3,5-tetrahydroimidazo[1,2-a]pyridine-7-carboxylic acid (IPCA) or its derivatives. This molecular fluorophore with conjugated double bonds, formed by a double cyclization reaction of citric acid and ethylenediamine as first shown by Y. Song, B. Yang, and coworkers in 2015, accounts for the fluorescence of the carbon dots. Cross-peaks in a 1H─13C HETCOR spectrum with brief 1H spin diffusion proved that IPCA is finely dispersed in the polyamide matrix. From quantitative 13C and 15N NMR spectra, a high concentration (18 ± 2 wt%) of IPCA in the carbon dots was determined. A pronounced gradient in 13C chemical-shift perturbations and peak widths, with the broadest lines near the COO group of IPCA, indicated at least partial transformation of the carboxylic acid of IPCA by amide or ester formation. 相似文献
99.
Rogozhkin S. V. Khomich A. A. Bogachev A. A. Nikitin A. A. Khoroshilov V. V. Kulevoy T. V. Fedin P. A. Pryanishnikov K. E. Lukyanchuk A. A. Raznitsyn O. A. Shutov A. S. Zaluzhnyi A. G. Vasiliev A. L. Presniakov M. Yu. 《Physics of Atomic Nuclei》2020,83(11):1519-1528
Physics of Atomic Nuclei - Improved mechanical properties of oxide dispersion strengthened (ODS) steels, the advanced materials for the reactor core, are due to the high density of uniformly... 相似文献
100.
Dr. Wan‐Ling Liu Ni‐Shin Yang Ya‐Ting Chen Stephen Lirio Cheng‐You Wu Prof. Chia‐Her Lin Prof. Hsi‐Ya Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):115-119
A green and sustainable strategy synthesizes clinical medicine warfarin anticoagulant by using lipase‐supported metal–organic framework (MOF) bioreactors (see scheme). These findings may be beneficial for future studies in the industrial production of chemical, pharmaceutical, and agrochemical precursors. 相似文献