全文获取类型
收费全文 | 4555篇 |
免费 | 603篇 |
国内免费 | 568篇 |
专业分类
化学 | 3419篇 |
晶体学 | 60篇 |
力学 | 198篇 |
综合类 | 49篇 |
数学 | 671篇 |
物理学 | 1329篇 |
出版年
2024年 | 6篇 |
2023年 | 44篇 |
2022年 | 96篇 |
2021年 | 121篇 |
2020年 | 140篇 |
2019年 | 169篇 |
2018年 | 159篇 |
2017年 | 117篇 |
2016年 | 225篇 |
2015年 | 216篇 |
2014年 | 259篇 |
2013年 | 300篇 |
2012年 | 330篇 |
2011年 | 369篇 |
2010年 | 262篇 |
2009年 | 266篇 |
2008年 | 348篇 |
2007年 | 301篇 |
2006年 | 263篇 |
2005年 | 226篇 |
2004年 | 208篇 |
2003年 | 224篇 |
2002年 | 250篇 |
2001年 | 202篇 |
2000年 | 119篇 |
1999年 | 95篇 |
1998年 | 57篇 |
1997年 | 36篇 |
1996年 | 30篇 |
1995年 | 26篇 |
1994年 | 32篇 |
1993年 | 26篇 |
1992年 | 14篇 |
1991年 | 15篇 |
1990年 | 12篇 |
1989年 | 9篇 |
1988年 | 14篇 |
1987年 | 13篇 |
1986年 | 13篇 |
1985年 | 18篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 14篇 |
1981年 | 11篇 |
1980年 | 12篇 |
1979年 | 5篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 5篇 |
1973年 | 5篇 |
排序方式: 共有5726条查询结果,搜索用时 15 毫秒
151.
Shu Ying Wu Xiao Min Zhang Hai Ou Tang Long Chen Bo Xuan Li 《Journal of solid state chemistry》2008,181(9):2171-2177
Ag/carbon hybrids were fabricated by the redox of glucose and silver nitrate (AgNO3) in the presence of imidazolium ionic liquid ([C14mim]BF4) under hydrothermal condition. Monodisperse carbon hollow sub-microspheres encapsulating Ag nanoparticles and Ag/carbon cables were selectively prepared by varying the concentration of ionic liquid. Other reaction parameters, such as reaction temperature, reaction time and the mole ratio of silver nitrate to glucose, play important roles in controlling the structures of the products. The products were characterized by XRD, TEM (HRTEM), SEM, energy-dispersive X-ray spectroscopy (EDX), FTIR spectroscopy and a Raman spectrometer. The possible formation mechanism was proposed. The catalytic property of the hybrid in the oxidation of 1-butanol by H2O2 was also investigated. 相似文献
152.
Dr. Yusen Li Xi Su Wenhao Zheng Dr. Jia-Jia Zheng Linshuo Guo Prof. Mischa Bonn Prof. Xingfa Gao Dr. Hai I. Wang Prof. Long Chen 《Angewandte Chemie (International ed. in English)》2023,62(10):e202216795
Targeted synthesis of kagome ( kgm ) topologic 2D covalent organic frameworks remains challenging, presumably due to the severe dependence on building units and synthetic conditions. Herein, two isomeric “two-in-one” monomers with different lengths of substituted arms based on naphthalene core (p-Naph and m-Naph) are elaborately designed and utilized for the defined synthesis of isomeric kgm Naph-COFs. The two isomeric frameworks exhibit splendid crystallinity and showcase the same chemical composition and topologic structure with, however, different pore channels. Interestingly, C60 is able to uniformly be encapsulated into the triangle channels of m-Naph-COF via in situ incorporation method, while not the isomeric p-Naph-COF, likely due to the different pore structures of the two isomeric COFs. The resulting stable C60@m-Naph-COF composite exhibits much higher photoconductivity than the m-Naph-COF owing to charge transfer between the conjugated skeletons and C60 guests. 相似文献
153.
Chen W Zhang HL Xu H Tok ES Loh KP Wee AT 《The journal of physical chemistry. B》2006,110(43):21873-21881
A SiC nanomesh is used as a nanotemplate to direct the epitaxy of C60 molecules. The epitaxial growth of C60 molecules on SiC nanomesh at room temperature is investigated by in situ scanning tunneling microscopy, revealing a typical Stranski-Krastanov mode (i.e., for the first one or two monolayers, it is a layer-by-layer growth or 2-D nucleation mode; at higher thicknesses, it changes to island growth or a 3-D nucleation mode). At submonolayer (0.04 and 0.2 ML) coverage, C60 molecules tend to aggregate to form single-layer C60 islands that mainly decorate terrace edges, leaving the uncovered SiC nanomesh almost free of C60 molecules. At 1 ML C60 coverage, a complete wetting layer of hexagonally close-packed C60 molecules forms on top of the SiC nanomesh. At higher coverage from 4.5 ML onward, the C60 stacking adopts a (111) oriented face-centered-cubic (fcc) structure. Strong bright and dim molecular contrasts have been observed on the first layer of C60 molecules, which are proposed to originate from electronic effects in a single-layer C60 island or the different coupling of C60 molecules to SiC nanomesh. These STM molecular contrast patterns completely disappear on the second and all the subsequent C60 layers. It is also found that the nanomesh can be fully recovered by annealing the C60/SiC nanomesh sample at 200 degrees C for 20 min. 相似文献
154.
Ning‐Hai Hu Katsuyuki Aoki Adegboye O. Adeyemo George N. Williams 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(9):1064-1066
In the title compound, 3‐[(4‐amino‐2‐methyl‐5‐pyrimidin‐1‐io)methyl]‐5‐(2‐hydroxyethyl)‐4‐methylthiazolium(2+) bis(tetrafluoroborate), C12H18N4OS2+·2BF4?, the divalent thiamine cation (in the F conformation) is associated with BF4? anions via two characteristic bridging interactions between the thiazolium and pyrimidinium rings, i.e. C—H?BF4??pyrimidinium and N—H?BF4??thiazolium interactions. Thiamine molecules are linked by N—H?O hydrogen bonds to form a helical chain structure. 相似文献
155.
Dr. Martin Schmidt Prof. Albert Masson Prof. Hai‐Ping Cheng Prof. Catherine Bréchignac 《Chemphyschem》2015,16(4):855-865
Adsorption and coadsorption studies on free silver clusters show that nitrogen physisorbs like rare gases, whereas oxygen chemisorbs with similarities and differences to bulk silver surfaces. Silver nanoparticles activate, or even dissociate adsorbed oxygen molecules. The global electron configurations of the adsorbent and adsorbate dominate the stability at small clusters. This is more important than geometry and site effects. Due to electronic shell effects and electron pairing, the activation of oxygen strongly varies with size. At more than 40 free electrons in the complex, such quantum effects start to blur. The size dependence becomes smoother and general trends govern the reactivity, which is driven by the interaction between the charge state of the nanoparticle and the charge transfer of the reaction. 相似文献
156.
157.
Hong Xia Dr. Jie Yang Hong‐Hua Fang Qi‐Dai Chen Dr. Hai‐Yu Wang Prof. Xiao‐Qiang Yu Prof. Yu‐Guang Ma Prof. Min‐Hua Jiang Prof. Hong‐Bo Sun Prof. 《Chemphyschem》2010,11(9):1871-1875
E, E‐1, 4‐bis[4′‐(N,N‐dibutylamino)styryl]‐2,5‐dimethoxy‐benzene (DBASDMB) organic crystals with high crystalline quality, large size and excellent optical properties are prepared. The linear and nonlinear properties in the crystal are comparatively studied. The relaxation dynamics pumped by two‐photon are very similar with that pumped by one‐photon. The crystal exhibits very strong two‐photon excited fluorescence and amplified spontaneous emission. Efficient two‐photon absorption, reasonably high fluorescent quantum efficiency, and high crystal quality together with stimulated emission make organic crystals ideal for the application in frequency upconversion and other optoelectronic fields. 相似文献
158.
Template-free cross-linking of single-stranded DNA bearing octadiynyl side chains at the 7-position of 8-aza-7-deazapurine moieties with bisfunctional azides is reported employing a Cu(I)-catalyzed azide-alkyne "bis-click" reaction. Bis-adducts were formed when the bis-azide:oligonucleotide ratio was 1:1; monofunctionalization occurred when the ratio was 15:1. Four-stranded DNA consisting of two cross-linked duplexes was obtained after hydridization. Cross-linked duplexes are as stable as individual duplexes when ligation was introduced at terminal positions; ligation at a central position led to a slight duplex destabilization. 相似文献
159.
Contribution of UV light to the decomposition of toluene in dielectric barrier discharge plasma/photocatalysis system 总被引:1,自引:0,他引:1
Hai Bao Huang Dai Qi Ye Ming Li Fu Fa Da Feng 《Plasma Chemistry and Plasma Processing》2007,27(5):577-588
The contribution of UV light from plasma and an external UV lamp to the decomposition of toluene in a dielectric barrier discharge
(DBD) plasma/UV system, as well as in a plasma/photocatalysis system was investigated. It was found that UV light from the
DBD reactor was very weak. Its contribution to the removal of toluene in the plasma/photocatalysis system could be ignored.
Whereas, the introduction of external UV light to the plasma significantly improves the removal efficiency of toluene by 20%.
The removal efficiency of toluene in the plasma/photocatalysis system increased about 22% and 16% when compared with a plasma
only system and plasma driven photocatalyst system, respectively. The increased toluene removal efficiency was mostly attributed
to the contribution of the synergy between plasma and UV light, but not to the synergy between plasma and photocatalysis.
The synergetic effect between plasma and photocatalysis was not significant. 相似文献
160.
Liang Chun Wu Long Qing Liu Hai Shan Jin Ming Liang Ma Xiao Li Zhao Ke Wen 《中国化学快报》2010,21(10):1263-1266
<正>Two pyrazine-contairting macrocyclic polyazomethines 2 and 3 were synthesized by direct[2 + 2]and[3 + 3]condensation reactions between 2,2'-[pyrazine-2,3-diylbis(oxy)]dibenzaldehyde(1) and hydrazine.Both 2 and 3 were characterized by NMR, HRMS,and their structures were determined via X-ray crystal diffraction studies. 相似文献