全文获取类型
收费全文 | 163篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
化学 | 96篇 |
力学 | 1篇 |
数学 | 58篇 |
物理学 | 15篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 4篇 |
2013年 | 4篇 |
2012年 | 8篇 |
2011年 | 22篇 |
2010年 | 5篇 |
2009年 | 6篇 |
2008年 | 6篇 |
2007年 | 12篇 |
2006年 | 14篇 |
2005年 | 4篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2000年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1978年 | 6篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1962年 | 1篇 |
1959年 | 1篇 |
1958年 | 1篇 |
1957年 | 1篇 |
1954年 | 1篇 |
1939年 | 1篇 |
1937年 | 1篇 |
1935年 | 1篇 |
排序方式: 共有170条查询结果,搜索用时 31 毫秒
51.
52.
53.
The effect of irradiation on the dielectric properties of nylon 66.6 and Mylar was studied. In the case of nylon the dielectric loss peak at 350 K measured with an annular frequency of 104 l/s disappeared due to irradiation and the peak at higher temperaturcs shifted to still higher temperatures. In Mylar the α-peak grew in magnitude, indicating an increase in amorphousness, while the β-peak decreased. A rough estimate for the decrease in the magnitude of the effective number of dipoles is presented. The irradiation was carried out up to fast neutron fluence of 3 × 1017 nvt and gamma dose of 1 × 109 rad. 相似文献
54.
55.
Ruusunen Jarno Ihalainen Mika Koponen Tarmo Torvela Tiina Tenho Mikko Salonen Jarno Sippula Olli Joutsensaari Jorma Jokiniemi Jorma Lähde Anna 《Journal of nanoparticle research》2014,16(2):1-11
Enteric-coated formulations can delay the release of drugs until they have passed through the stomach. However, high concentration of drugs caused by rapidly released in the small intestine leads to the intestinal damage, and frequent administration would increase the probability of missing medication and reduce the patient compliance. To solve the above-mentioned problems, aspirin-loaded enteric-coated sustained-release nanoparticles with core–shell structure were prepared via one-step method using coaxial electrospray in this study. Eudragit L100-55 as pH-sensitive polymer and Eudragit RS as sustained-release polymer were used for the outer coating and inner core of the nanoparticles, respectively. The maximum loading capacity of nanoparticles was 23.66 % by changing the flow rate ratio of outer/inner solutions, and the entrapment efficiency was nearly 100 %. Nanoparticles with core–shell structure were observed via fluorescence microscope and transmission electron microscope. And pH-sensitive and sustained drug release profiles were observed in the media with different pH values (1.2 and 6.8). In addition, mild cytotoxicity in vitro was detected, and the nanoparticles could be taken up by Caco-2 cells within 1.0 h in cellular uptake study. These results indicate that prepared enteric-coated sustained-release nanoparticles would be a more safety and effective carrier for oral drug delivery. 相似文献
56.
Olli Dahl Hannu Nurmesniemi 《International journal of environmental analytical chemistry》2013,93(1):61-73
Abstract The herbicide trifluralin was analysed by adsorptive stripping voltammetry on a glassy carbon electrode. The linear concentration range was 2.5 × 10?7 M – 1.25 × 10?6M when using 5-min preconcentration at open circuit conditions in Britton-Robinson buffer of pH 7.0. The detection limit of trifluralin was 2.5 × 10?8M. The relative standard deviation was 3.3% at a concentration of 1.0 × 10?6M (n=5). The method was applied to the determination of trifluralin in soil with good recovery. 相似文献
57.
Koivunen JT Nissinen L Käpylä J Jokinen J Pihlavisto M Marjamäki A Heino J Huuskonen J Pentikäinen OT 《Journal of the American Chemical Society》2011,133(37):14558-14561
Collagen binding integrins are an important family of cell surface receptors that mediate bidirectionally signals between the interior of the cell and the extracellular matrix. The protein-protein interactions between cells and collagen are necessary for many physiological functions, but also promote diseases. For example, the interaction of α2β1 integrin and collagen has been shown to have an important role in thrombus formation and cancer spread. The fact that the discovery of small molecules that can block such protein-protein interactions is highly challenging has significantly hindered the discovery of pharmaceutical agents to treat these diseases. Here, we present a rationally designed novel fluorescent molecule that can be synthesized in just a few minutes from commercially available starting materials. This molecule blocks the protein-protein interaction between α2β1 integrin and collagen, and due to its fluorescent properties, it can be employed in wide variety of biological applications. 相似文献
58.
Werner J. Sieber Mathias Wolfgruber Fritz R. Kreissl Olli Orama 《Journal of organometallic chemistry》1984,270(2):C41-C44
Transition-metal-substituted η1-ketenes react with methanol to form methyl acetate with the metal in the α-position. X-Ray analysis proves the trans-position of the two carbonyl ligands. 相似文献
59.
Weighted grouping problems are shown to have an equivalent reduced form, which is often considerably smaller than the original problem. Although the reduction may be small for randomly generated problems, real-life problems often contain non-random properties that greatly increase the effect of reduction. We give an efficient algorithm to build the reduced problem instance, and analyse the expected amount of reduction for certain statistical distributions and real-life data. In addition, we briefly discuss the effect of reduction on traditional solving methods of the grouping problem. The results show clearly the usefulness of problem reduction: it is computationally cheap to apply and may make the reduced problem solvable in a practical time whilst the original one is not. The method is readily applicable to the job grouping problem of printed circuit board (PCB) printing industry. 相似文献
60.
Template‐Free Supracolloidal Self‐Assembly of Atomically Precise Gold Nanoclusters: From 2D Colloidal Crystals to Spherical Capsids 下载免费PDF全文
Dr. Nonappa Dr. Tanja Lahtinen M. Sc. Johannes. S. Haataja Dr. Tiia‐Riikka Tero Prof. Hannu Häkkinen Prof. Olli Ikkala 《Angewandte Chemie (International ed. in English)》2016,55(52):16035-16038
We report supracolloidal self‐assembly of atomically precise and strictly monodisperse gold nanoclusters involving p‐mercaptobenzoic acid ligands (Au102‐pMBA44) under aqueous conditions into hexagonally packed monolayer‐thick two‐dimensional facetted colloidal crystals (thickness 2.7 nm) and their bending to closed shells leading to spherical capsids (d ca. 200 nm), as controlled by solvent conditions. The 2D colloidal assembly is driven in template‐free manner by the spontaneous patchiness of the pMBA ligands around the Au102‐pMBA44 nanoclusters preferably towards equatorial plane, thus promoting inter‐nanocluster hydrogen bonds and high packing to planar sheets. More generally, the findings encourage to explore atomically precise nanoclusters towards highly controlled colloidal self‐assemblies. 相似文献