全文获取类型
收费全文 | 2442篇 |
免费 | 131篇 |
国内免费 | 489篇 |
专业分类
化学 | 1491篇 |
晶体学 | 3篇 |
力学 | 106篇 |
综合类 | 8篇 |
数学 | 482篇 |
物理学 | 972篇 |
出版年
2022年 | 11篇 |
2021年 | 11篇 |
2020年 | 9篇 |
2019年 | 6篇 |
2018年 | 19篇 |
2017年 | 12篇 |
2016年 | 32篇 |
2015年 | 24篇 |
2014年 | 106篇 |
2013年 | 64篇 |
2012年 | 42篇 |
2011年 | 400篇 |
2010年 | 213篇 |
2009年 | 199篇 |
2008年 | 29篇 |
2007年 | 41篇 |
2006年 | 82篇 |
2005年 | 150篇 |
2004年 | 403篇 |
2003年 | 218篇 |
2002年 | 168篇 |
2001年 | 202篇 |
2000年 | 41篇 |
1999年 | 42篇 |
1998年 | 65篇 |
1997年 | 43篇 |
1996年 | 31篇 |
1995年 | 29篇 |
1994年 | 32篇 |
1993年 | 79篇 |
1992年 | 67篇 |
1991年 | 31篇 |
1990年 | 25篇 |
1989年 | 31篇 |
1988年 | 20篇 |
1987年 | 3篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1982年 | 3篇 |
1977年 | 3篇 |
1932年 | 2篇 |
1928年 | 2篇 |
1919年 | 3篇 |
1917年 | 2篇 |
1916年 | 2篇 |
1911年 | 4篇 |
1910年 | 3篇 |
1909年 | 3篇 |
1907年 | 3篇 |
排序方式: 共有3062条查询结果,搜索用时 15 毫秒
51.
52.
ShuXiaCAO JianChenZHANG MingYuNIU KuiLU XinChengLIAO YuFenZHAO 《中国化学快报》2004,15(6):652-654
N-Phosphoryl peptide libraries were constructed by transformation from homo-oligopeptide libraries, which was synthesized by self-assembly of amino acids with the assistance of phosphorus oxychloride. Electrospray ionization mass spectrometry (ESI-MS) was used to monitor the reaction. 相似文献
53.
CAI Shu-Hui LI Jun LIU Chun-WanFujian Institute of Research on the Structure of Matter Chinese Academy of Sciences State Key Laboratory of Structural Chemistry Fuzhou Fujian China 《中国化学》1994,12(5):385-391
The band structures of several analogous superconducting A-15 type solid compounds, Nb3X (X=Si, Ge, Sn, Pb), have been calculated by use of the tight-binding method within the Extended Huckel approximation (EHT). By analysis of their energy bands, densities of states and crystal orbital overlap populations, the dependence of the superconducting transition temperatures (Tc) on the electronic structures and bondings is qualitatively elucidated. 相似文献
54.
JIANG Hua ZHANG Quanxing CHEN Jinlong Nanjing Electric Power Automation Equipment General Factory The State Power Cooperation of China Nanjing China The State Key Laboratory of Pollution Control & Resources Reuse Dept. of Environme 《Chinese Journal of Reactive Polymers》2002,(1)
1. INTRODUCTION 1,2,4-acid (1-Amino-2-naphthol-4-sulfonic acid) is among the most important naphthalene derivatives which are widely used as the intermediates of dyestuffs. In its production process, however, high strength wastewater streams are gene… 相似文献
55.
56.
57.
本文介绍FAB质谱的原理、功能和优点。综述了FAB机理,讨论了影响FAB谱的因素。归纳了FAB法在金属有机配合物研究中的应用。 相似文献
58.
A series of Mo-impregnated Hβ samples, with MoO3 loading in Hβ zeolite in the mass fraction range of 0. 5%-6.0%, were studied by means of XRD and IR in order to characterize their structures. Mo/Hβ sampies‘ crystallinity almost linearly decreases with increasing the amount of MoO3 loaded, The IR spectra and XRD patterns suggest that the progressive destabilization of the Hβ zeolite structure is caused by increasing Mo loading in (MoO3 Hβ zeolite). During the calcination, Al2(MoO4)3 formed from the dealumination of Hβ zeolite, causes the substantially partial breakdown of the zeolite framework when the Mo loading in MoO3 Hβ is relatively high. 相似文献
59.
CHEN Jie DONG Xin-shu GUO Xing-gang The Affiliated Tumor Hospital Harbin Medical University Harbin P. R. China 《高等学校化学研究》2008,24(6)
To explore the functional mechanism of Resveratrol against colon cancer cells Is174t and the growth of colon cancer tissue of tumor-bearing mice,MTT method was used to observe the functions of resveratrol for inhibition against cells ls174t in vitro.Transmission electron microscope was used to observe the cell apoptosis.FCM assay was performed to measure the change of the cell apoptosis rate and of cell cycle,RT-PCR method was used to detect the expressions of bc1-2 and bax mRNA.Western blot method was used to detect the expressions of bc1-2 and bax protein.Cells isi74t were transplanted subcutaneously to nude mice to observe the effect of resveratrol on the growth of subcutaneously transplanted tumor.RT-PCR method was used to detect the expressions of bc1-2 and bax mRNA in the tumor tissue.Western blot method was used to detect the expressions of bc1-2 and bax protein in the tumor tissue.Resveratrol has an effect of inhibiting proliferation of cells ls174t in vitro(P<0.01).It is able to induce the apoptosis of cells Is174t,causing the decrease in the expression of bc1-2 and the increase in the expression of bax.Resveratrol could inhibit the growth of subcutaneously transplanted tumor of nude mice(P<0.05),causing the decrease in the expression of bc1-2 and the increase in the expression of bax.Resveratrol can inhibit the growth of cells 174t and the growth of subcutaneously transplanted tumor.The mechanism is possibly related to the induction of the cell apoptosis and the regulation of bc1-2/bax expression. 相似文献
60.
微乳液进样火焰原子吸收光度法测定食品中的微量锰 总被引:8,自引:0,他引:8
研究了多种表面活性剂及微乳液对火焰原子吸收光谱法测定锰的增敏作用,并选择增敏作用最强的微乳液作为锰测定的增敏试剂,拟定了测定锰的新方法。 相似文献