全文获取类型
收费全文 | 14249篇 |
免费 | 1929篇 |
国内免费 | 3184篇 |
专业分类
化学 | 14562篇 |
晶体学 | 218篇 |
力学 | 369篇 |
综合类 | 160篇 |
数学 | 100篇 |
物理学 | 3953篇 |
出版年
2024年 | 69篇 |
2023年 | 200篇 |
2022年 | 526篇 |
2021年 | 601篇 |
2020年 | 860篇 |
2019年 | 655篇 |
2018年 | 452篇 |
2017年 | 487篇 |
2016年 | 585篇 |
2015年 | 599篇 |
2014年 | 646篇 |
2013年 | 1130篇 |
2012年 | 945篇 |
2011年 | 772篇 |
2010年 | 595篇 |
2009年 | 741篇 |
2008年 | 751篇 |
2007年 | 862篇 |
2006年 | 810篇 |
2005年 | 679篇 |
2004年 | 716篇 |
2003年 | 670篇 |
2002年 | 687篇 |
2001年 | 565篇 |
2000年 | 481篇 |
1999年 | 368篇 |
1998年 | 369篇 |
1997年 | 346篇 |
1996年 | 306篇 |
1995年 | 332篇 |
1994年 | 265篇 |
1993年 | 242篇 |
1992年 | 234篇 |
1991年 | 162篇 |
1990年 | 150篇 |
1989年 | 95篇 |
1988年 | 91篇 |
1987年 | 61篇 |
1986年 | 34篇 |
1985年 | 36篇 |
1984年 | 27篇 |
1983年 | 13篇 |
1982年 | 20篇 |
1981年 | 20篇 |
1980年 | 27篇 |
1979年 | 19篇 |
1978年 | 16篇 |
1977年 | 8篇 |
1976年 | 10篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Three cucurbit[6]uril (CB[6])-based polyrotaxanes [Cu(H2 C6N4)(CB[6])]Cl4·12H2O (1), [Co(H2 C6N4)(CB[6])]Cl4·14H2O (2) and [Ag(C6N4)(CB[6])]NO3·7H2O (3) are prepared using N,N′-bis(4-pyridylmethyl)-1,6-hexanediamine (C6N4) threading into CB[6]'s and metal ions' assistance. Single-crystal X-ray diffraction analyses reveal that polyrotaxanes 1, 2 and 3 all have 1D chain structure where 1 and 2 are linear and 3 has two shapes, linear and sawtooth, respectively. The effects of guest molecules, metal and counter ions as well as intermolecular weak interactions on the architectures of polyrotaxanes are discussed. 相似文献
992.
Yin Li Zsolt Csók László Kollár Koichi Iwata Erzsébet Szász 《Supramolecular chemistry》2013,25(6):374-378
2-Methylresorcinarene and its methylene-bridged cavitand derivative as host compounds were investigated in selective complexation of alkali metal ions as guests in methanol media by photoluminescence measurements. These host molecules possess either flexible (2-methylresorcinarene) or rigid (cavitand) molecular skeleton. The Benesi–Hildebrand method and the van't Hoff theory have been applied to determine the stability constants and the thermodynamic parameters, respectively. Considerable interactions between 2-methylresorcinarene and Li+ or Na+ ions have been observed while the rigid cavitand derivative can interact only with K+ or Cs+ ions. Neither the complexes of 2-methylresorcinarene with K+ or Cs+ nor those of the cavitand derivative with Li+ or Na+ ions are stable at room temperature in methanol media. Quantum-chemical investigations justified that only solvated Li+ and Na+ ions can form stable complexes with 2-methylresorcinarene while unsolvated K+ and Cs+ ions form stable complexes with the methylene-bridged cavitand. These results highlight that the stability of the guest solvation shell and its size could play a key role in the selectivity behaviour of host molecules. 相似文献
993.
994.
995.
996.
997.
998.
999.
Dr. Markus Lampimäki Dr. Veronika Zelenay Dr. Adéla Křepelová Dr. Zhi Liu Rui Chang Dr. Hendrik Bluhm Dr. Markus Ammann 《Chemphyschem》2013,14(11):2419-2425
Ozone adsorption and decomposition on metal oxides is of wide interest in technology and in atmospheric chemistry. Here, ozone‐adsorption‐induced band bending is observed on Ti‐ and Fe‐oxide model surfaces under dry and humid conditions. Photoelectron spectroscopic studies indicate the effect of charge transfer to O3, which limits the surface coverage of the precursor to decomposition reactions. This is also consistent with the negative pressure dependence observed in previous studies. These results contribute to our fundamental understanding of ozone adsorption and decomposition mechanisms on metal oxides of environmental and technological relevance. 相似文献
1000.
Nanofibrous materials have been extensively investigated and used as building blocks for various nanodevices, due to their unique one‐dimensional structures. Recently, novel membranes constructed by using nanofibers have been reported by various techniques. Here, we will give a critical review of our recent research on the general solution processed unique sub‐3 nm thin metal hydroxide nanofibers and their application for constructing ultrathin separation membranes via filtration technique. The superior separation performances of these membranes hold the promising future for pressure‐driven membrane separation processes. 相似文献