全文获取类型
收费全文 | 10553篇 |
免费 | 1501篇 |
国内免费 | 900篇 |
专业分类
化学 | 10432篇 |
晶体学 | 80篇 |
力学 | 89篇 |
综合类 | 30篇 |
数学 | 9篇 |
物理学 | 2314篇 |
出版年
2024年 | 24篇 |
2023年 | 169篇 |
2022年 | 481篇 |
2021年 | 536篇 |
2020年 | 704篇 |
2019年 | 553篇 |
2018年 | 479篇 |
2017年 | 559篇 |
2016年 | 766篇 |
2015年 | 753篇 |
2014年 | 824篇 |
2013年 | 1020篇 |
2012年 | 877篇 |
2011年 | 860篇 |
2010年 | 653篇 |
2009年 | 665篇 |
2008年 | 575篇 |
2007年 | 530篇 |
2006年 | 423篇 |
2005年 | 329篇 |
2004年 | 239篇 |
2003年 | 235篇 |
2002年 | 194篇 |
2001年 | 148篇 |
2000年 | 105篇 |
1999年 | 74篇 |
1998年 | 45篇 |
1997年 | 33篇 |
1996年 | 17篇 |
1995年 | 21篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 10篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
103.
Ali Rafati Rik ter Veen David G. Castner 《Surface and interface analysis : SIA》2013,45(11-12):1737-1741
With the widespread use of engineered nanoparticles for biomedical applications, detailed surface characterization is essential for ensuring reproducibility and the quality/suitability of the surface chemistry to the task at hand. One important surface property to be quantified is the overlayer thickness of self‐assembled monolayer (SAM) functionalized nanoparticles, as this information provides insight into SAM ordering and assembly. We demonstrate the application of high sensitivity low‐energy ion scattering (HS‐LEIS) as a new analytical method for the fast thickness characterization of SAM functionalized gold nanoparticles (AuNPs). HS‐LEIS demonstrates that a complete SAM is formed on 16‐mercaptohexadecanoic acid (C16COOH) functionalized 14 nm AuNPs. HS‐LEIS also experimentally provides SAM thickness values that are in good agreement with previously reported results from simulated electron spectra for surface analysis of X‐ray photoelectron spectroscopy data. These results indicate HS‐LEIS is a valuable surface analytical method for the characterization of SAM functionalized nanomaterials. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
104.
105.
Li Qiang Wu 《应用有机金属化学》2013,27(3):148-154
Nano n‐propylsulfonated γ‐Al2O3 is easily prepared by the reaction of nano γ‐Al2O3 with 1,3‐propanesultone. This reagent can be used as an efficient catalyst for the synthesis of spiro [indoline‐3,4‐pyrazolo[3,4‐e][1,4]thiazepine]diones in aqueous media. This new method consistently has the advantages of excellent yields and short reaction times. Further, the catalyst can be reused and recovered several times. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
106.
An efficient and eco-friendly method is reported for the synthesis of 2-substituted-2,3-dihydroquinazolin -4(1 H)-ones from direct cyclocondensation of anthranilamide with aldehydes and ketones using N-propylsulfamic acid supported onto magnetic Fe3O4 nanoparticles(MNPs-PSA) as a recoverable and recyclable nanocatalyst in good to excellent yields in water at 70℃.The catalyst was readily separated using an external magnet and reusable without significant loss of their catalytic efficiency. 相似文献
107.
108.
《高分子科学杂志,A辑:纯化学与应用化学》2013,50(10):1259-1264
ABSTRACT Methods have been found for sintering titania nanoparticles at low temperature, e.g., <150°C, and for rapid sensitization of the sintered particles. This discovery means that dye-sensitized, titania solar cells can be made on flexible substrates, such as poly(ethylene terephthalate), in a continuous roll-to-roll manufacturing process. The ability to produce solar cells in a continuous fashion should substantially lower the cost of the cells compared to batch processed, on-glass cells. The combined attributes of spectral sensitivity, flexibility, light weight, impact resistance and low cost should find utility a variety of handheld appliances in both indoor and outdoor situations. In its most advanced state of development, this technology would find application in off-grid power generation and thus provide the opportunity of bringing solar generated electricity to rural areas of the world. 相似文献
109.
Krzysztof A. Kunert 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):1469-1488
In this paper are presented the static and dynamic mechanical investigation of chemically cross-linked low density polyethylene (XLPE) prepared in our laboratory. This polymer has been tested mechanically at different frequencies, amplitudes, and temperatures as a function of cross-link density which is indicated to some extent by the amount of peroxide used in the cross-linking. The main findings can be described as follows: mechanical damping in XLPE at the α-relaxation point as a function of peroxide concentration is different for shear and compression modes of deformation. Moreover, the dynamic investigation at very small amplitudes indicated two relatively rigid structures. One structure at low concentration of peroxide is attributed to excessive crystallinity; the other one at the high peroxide concentration is probably due to the very regular and perfect polyethylene network. These two interesting structures are not detected by dynamical testing with large amplitudes. As far as Young's modulus as a function of peroxide concentration is concerned, we conclude that in this polymer this factor does not depend on the crystallinity but on changes of the so-called hard amorphous phase. These findings are consistent with our previous structural investigation. 相似文献
110.
Edith Chow Burkhard Raguse Karl‐H. Müller Lech Wieczorek Avi Bendavid James S. Cooper Lee J. Hubble Melissa S. Webster 《Electroanalysis》2013,25(10):2313-2320
The porosity of 1‐hexanethiol‐functionalised gold nanoparticle films was assessed and utilised as chemiresistor sensors. Electrochemical capacitance measurements showed that the accessibility of electrolytes of different ionic strengths into the pores depended on the thickness of the electric double layer formed. A large variation in capacitance was measured in 0.01–1000 mM NaClO4, implying a wide pore size distribution. The change in morphology of the nanoparticle films upon storage in air, water and ethanol for two weeks was investigated. There was a significant decrease in the electrochemical capacitance at high electrolyte concentrations for the ethanol‐stored films compared to the freshly‐prepared films suggesting a decrease in the number of small pores of radii in the range of 0.3–3 nm. This was further supported by optical topographical measurements where a decrease in the thickness of ethanol‐stored films was observed relative to the freshly‐prepared films. The porous nature of the nanoparticle films was found to have an effect on the chemical sensing behaviour. When used as chemiresistor sensors, for the detection of heptane in water, the ethanol‐stored films provided larger resistance changes and longer response times. This suggests that the more densely packed ethanol‐stored films provided more sites that enabled film swelling, and that diffusion of the analyte occurred through the narrower water‐filled pores. This demonstrates the effect of different storage conditions on film morphology and subsequently sensor response. 相似文献