全文获取类型
收费全文 | 280篇 |
免费 | 12篇 |
国内免费 | 2篇 |
专业分类
化学 | 208篇 |
力学 | 5篇 |
数学 | 28篇 |
物理学 | 53篇 |
出版年
2023年 | 2篇 |
2022年 | 13篇 |
2021年 | 15篇 |
2020年 | 17篇 |
2019年 | 13篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 14篇 |
2015年 | 6篇 |
2014年 | 17篇 |
2013年 | 23篇 |
2012年 | 15篇 |
2011年 | 15篇 |
2010年 | 7篇 |
2009年 | 15篇 |
2008年 | 16篇 |
2007年 | 11篇 |
2006年 | 6篇 |
2005年 | 15篇 |
2004年 | 10篇 |
2003年 | 9篇 |
2002年 | 7篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1991年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1916年 | 2篇 |
排序方式: 共有294条查询结果,搜索用时 78 毫秒
21.
Gold nanoparticles have unique and excellent medical and nonmedical properties and application compared with other metallic nanoparticles. Recently, they have been used for the prevention, control, and treatment of bacterial and fungal diseases. In the recent study, fresh and clean leaves of Allium noeanum Reut. ex Regel leaves have been used for the synthesis of gold nanoparticles. Also, we evaluated the cytotoxicity, antioxidant, and antibacterial properties of HAuCl4, A. noeanum, and the synthesized nanoparticles (Au NPs). These nanoparticles were analyzed by FT‐IR, UV, XRD, EDS, FE‐SEM, and TEM tests. FTIR results offered antioxidant compounds in the plant were the sources of reducing power, reducing gold ions to Au NPs. In TEM images revealed an average diameter of 10‐30 nm. At the beginning of biological experiments, DPPH free radical scavenging test was carried out to examine the antioxidant property. Also, in the bacterial part of this study, the concentration of HAuCl4, A. noeanum, and AuNPs with minimum dilution and no turbidity was considered MIC. To determine MBC, 60 μL of MIC and three preceding chambers were cultured on Muller Hinton Agar. The minimum concentration with no bacterial growth was considered MBC. Au NPs revealed excellent antioxidant potential against DPPH, non‐toxicity property against human umbilical vein endothelial cells, and antibacterial activities against Streptococcus pneumonia, Bacillus subtilis, Staphylococcus aureus, Staphylococcus saprophyticus, Salmonella typhimurium, Pseudomonas aeruginosa, Shigella flexneri, and Escherichia coli O157:H7. These findings show that the inclusion of A. noeanum extract improves the solubility of Au NPs, which led to a notable enhancement in the antioxidant and antibacterial effects. 相似文献
22.
Gorazd Hribar Andrej Žnidaršič Marjan Bele Uroš Maver Simon Caserman Miran Gaberšček Vladka Gaberc-Porekar 《Journal of nanoparticle research》2011,13(7):3019-3032
The authors’ intention was to prepare nanometer-sized zinc-phosphate nanoparticles that would be capable of binding histidine-rich
TNF-α analogs onto their surface via a coordinative bond. Zinc-phosphate nanoparticles with a size of around 60 nm were prepared
by a wet precipitation method and characterized using SEM, EDX, XRD, and DLS. First, BSA was bound as a testing protein, afterward
two TNF-α analogs with decreased activity were bound to the described nanoparticles. The efficiency of binding and the existence
of coordinative bond were confirmed with SDS-PAGE analysis. During binding, particle storage, and release experiments, the
prepared TNF-α analogs retained their biological activity—hence the epitopes necessary for formation of antibodies stayed
intact. The particle size did not change within a period of 2 weeks. No significant agglomeration was observed, the particles
could be quickly dispersed in ultrasound. The present nanoparticles and the general approach of coordinative binding are widely
applicable for natural and engineered histidine-rich proteins. The nanoparticles bearing appropriate TNF-α analogs could also
be potentially used for active immunotherapy to tackle the chronic inflammatory diseases associated with pathogenically elevated
levels of TNF-α. 相似文献
23.
Ljubo Golič Jože Slivnik Marjan Levstek Anka Rihar 《Monatshefte für Chemie / Chemical Monthly》1968,99(1):289-290
Ohne Zusammenfassung 相似文献
24.
Efficient hydrogen peroxide enhanced iodofunctionalisation of ketones, 1,3-dicarbonyl derivatives and activated aromatic molecules using elemental iodine in water is achieved, whereas alkynes were stereoselectively converted into (E)-1,2-diiodoalkenes. 相似文献
25.
26.
27.
In this paper, radial basis function (RBFs) based mesh-free method is implemented to find numerical solution of the Kuramoto-Sivashinsky equations. This approach has an edge over traditional methods such as finite-difference and finite element methods because it does not require a mesh to discretize the problem domain, and a set of scattered nodes in the domain of influence provided by initial data is required for the realization of the method. The accuracy of the method is assessed in terms of the error norms L2,L∞, number of nodes in the domain of influence, free parameter, dependent parameter RBFs and time step length. Numerical experiments demonstrate accuracy and robustness of the method for solving a class of nonlinear partial differential equations. 相似文献
28.
Zahra Mohammadpour Zahra Sadat Hashemi Fatemeh Malekian Jebeli Sahel Ghasemzadeh Esfandyar Askari Mandana Akbary-Yekta Ramin Sarrami-Forooshani 《Particle & Particle Systems Characterization》2021,38(12):2100162
Iron oxychloride (FeOCl) is known for reactive oxygen species (ROS) generation through Fenton chemistry. The activity of FeOCl is preserved in the slightly acidic pH value of the tumor microenvironment (pH 6.5−6.9). Such property can be advantageous in biobased systems, where ROS generation can be modulated in slightly acidic conditions, which is characteristic of the solid tumor microenvironment. In the present study, BSA-stabilized FeOCl nanosheets (NSs) are synthesized and characterized by transmission electron microscope, Fourier transform infrared spectroscopy, zeta potential analysis, dynamic light scattering, and UV–vis spectroscopy. The morphology of the nanoparticles is flake-like, and their hydrodynamic diameter is around 200 nm. MTT, apoptosis assay, and trypan blue staining evaluate the toxicity of FeOCl NSs toward the 4T1 cell line. It is found that the toxicity of the NSs is higher in physiological conditions of solid tumors (pH 6.5, H2O2 100 × 10−6 m ) than in the conditions of healthy organs (pH 7.4). Specifically, cancer cells are in their late apoptotic stage by more than eight times higher at pH 6.5 than pH 7.4. The toxicity results are in agreement with the in vitro catalytic assay of the NSs. Therefore, the FeOCl NSs can be the building blocks for constructing chemodynamic therapy agents. 相似文献
29.
Radial basis function method is an effective tool for solving differential equations in engineering and sciences. Many radial basis functions contain a shape parameter c which is directly connected to the accuracy of the method. Rippa [1] proposed an algorithm for selecting good value of shape parameter c in RBF-interpolation. Based on this idea, we extended the proposed algorithm for selecting a good value of shape parameter c in solving time-dependent partial differential equations. 相似文献
30.
The domino Knoevenagel hetero-Diels-Alder reaction of the O-propargylated salicylaldehydes and 4-hydroxycoumarin leads to pyrano[2,3-c]coumarins 3 and pyrano[2,3-c]chromones 4 in high yield in the presence of CuI as a Lewis acid. In all cases, the reaction was shown to exhibit high regioselectivity and form product 3 as main product. 相似文献