全文获取类型
收费全文 | 99467篇 |
免费 | 4605篇 |
国内免费 | 3923篇 |
专业分类
化学 | 40589篇 |
晶体学 | 1262篇 |
力学 | 7876篇 |
综合类 | 315篇 |
数学 | 34170篇 |
物理学 | 23783篇 |
出版年
2024年 | 54篇 |
2023年 | 362篇 |
2022年 | 612篇 |
2021年 | 712篇 |
2020年 | 821篇 |
2019年 | 952篇 |
2018年 | 11060篇 |
2017年 | 10869篇 |
2016年 | 6990篇 |
2015年 | 1936篇 |
2014年 | 1561篇 |
2013年 | 1956篇 |
2012年 | 5881篇 |
2011年 | 12469篇 |
2010年 | 7242篇 |
2009年 | 7579篇 |
2008年 | 8309篇 |
2007年 | 10204篇 |
2006年 | 1748篇 |
2005年 | 2656篇 |
2004年 | 2608篇 |
2003年 | 2808篇 |
2002年 | 1918篇 |
2001年 | 953篇 |
2000年 | 864篇 |
1999年 | 603篇 |
1998年 | 487篇 |
1997年 | 366篇 |
1996年 | 396篇 |
1995年 | 288篇 |
1994年 | 254篇 |
1993年 | 231篇 |
1992年 | 147篇 |
1991年 | 170篇 |
1990年 | 122篇 |
1989年 | 110篇 |
1988年 | 108篇 |
1987年 | 89篇 |
1986年 | 93篇 |
1985年 | 85篇 |
1984年 | 64篇 |
1983年 | 55篇 |
1982年 | 58篇 |
1981年 | 58篇 |
1980年 | 61篇 |
1979年 | 57篇 |
1978年 | 41篇 |
1914年 | 45篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
A new analytical method for the determination of uric acid (UA) by the perturbation of UA on the Belousov-Zhabotinsky oscillating reaction is proposed. The method is based on the linear relationship between the changes in the oscillating period and the concentration of UA. The calibration curve is linear over the range of 2.0 × 10−5 to 5.0 × 10−4 M, with a detecting limit of 3.28 × 10−6 M. The method features good precision (R.S.D.: 3.59%) and excellent throughput (10 samples h−1). The possible mechanism of the perturbation of UA on the oscillating reaction is discussed. 相似文献
992.
993.
Mokhammad Arif G. V. Samoilenko Yu. G. Sergeev L. N. Blinov 《Russian Journal of Applied Chemistry》2005,78(9):1398-1402
The phase diagram of the system Sb2S3-AgI was constructed from data of the differential thermal and X-ray phase analyses. The physicochemical properties of glassy and crystalline alloys were studied. 相似文献
994.
The title compound, (isopropylxanthato)(phenyl)mercury(I), was synthesized and characterized by elemental analysis, IR and thermogravimetric analysis. Density functional theory (DFT) method calculations were performed at B3LYP/CEP-121G and B3LYP/CEP-31G levels of theory, respectively. Vibrational frequencies were predicted, assigned, compared with the experimental values, and they are supported each other. The calculated results show that the strength of bond Hg—C is stronger than that of Hg—S, which is good agreement with the experimental data. The calculations of the second order optical nonlinearity and electronic absorption spectra are also performed. 相似文献
995.
ShuXiaCAO JianChenZHANG JunXU XinChengLIAO YuFenZHAO 《中国化学快报》2004,15(7):817-820
Hydrolysis procedure of N-phosphoryl phenylalanine (DIPP-Phe) was studied by HPLC-ESI-MS/MS. The results showed that (HO)(i-PrO)P(O)Phe was the main intermediate and the hydrolysis of DIPP-Phe also occurred through a penta-coordinate transition state. 相似文献
996.
聚合物强化辐射交联研究进展 总被引:1,自引:0,他引:1
本文综述卫应用含有多个C=C不饱和基团的多官能团单体来强化辐射交联聚合物的研究进展,对强化交联的反应机理、多官能团单体的强化交联行为、强化交联的影响因素及强化交联的研究表征方法进行了介绍。 相似文献
997.
ZHU Jun ZHANG Yun CHEN Hao CHE Yun-Xia ZHENG Ji-Min ② 《结构化学》2006,25(8):1011-1013
1 INTRODUCTION Nonlinear optics (NLO) is at the forefront of cur- rent researches because of its importance in provi- ding the key functions of frequency shifting, optical modulation, optical switching, optical logic and op- tical memory for the emerging … 相似文献
998.
Ch. V. Subba Reddy Y. Y. Qi W. Jin Q. Y. Zhu Z. R. Deng W. Chen Sun-il Mho 《Journal of Solid State Electrochemistry》2007,11(9):1239-1243
Molybdenum trioxide (MoO3) xerogel films modified with poly(vinyl alcohol)+poly(vinyl pyrrolidone) (PVP+PVA) polyblends were obtained by ion-exchange
method with sol-gel technique. Investigations were conducted using X-ray “diffractometry”, Fourier transform infrared spectroscopy,
and cyclic voltammetry. The results show that the H atoms in polyblend are H-bonded with the O atoms in the Mo=O bonds of
MoO3 xerogel, which effectively shield the electrostatic interaction between MoO3 interlayer and Li+ ions when MoO3 xerogel is modified by the intercalation of (PVP+PVA). The reversibility of the insertion/extraction of Li+ ions is greatly improved by the modification with polyblend of MoO3 nanocomposite films. MoO3 and (PVP+PVA)
x
MoO3 (x = 0, 0.5) nanobelts were obtained by a simple hydrothermal process from MoO3 sol. The electrochemical cells with configuration Li/(LiPF6+EC+DMC)/MoO3 modified by (PVP+PVA) were fabricated and their discharge profiles studied. 相似文献
999.
脉冲激光诱发等离子体的谱诊断技术用来对其电子密度和电子温度的测量结果与理论计算进行了比较,同时讨论了运用这个方法的物理条件. 相似文献
1000.
聚乙烯醇双胺肟螯合纤维的合成及其吸附性能 总被引:5,自引:0,他引:5
利用预辐接技法合成了聚乙烯醇双胺肟螯合纤维。研究了影响接枝率和胺肟基团含量的因素,讨论了吸附酸度、吸附时间对Cu(Ⅱ)离子吸附容量的影响。 相似文献