全文获取类型
收费全文 | 107篇 |
免费 | 5篇 |
专业分类
化学 | 78篇 |
晶体学 | 3篇 |
力学 | 1篇 |
数学 | 16篇 |
物理学 | 14篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 6篇 |
2013年 | 10篇 |
2012年 | 2篇 |
2011年 | 6篇 |
2010年 | 5篇 |
2009年 | 9篇 |
2008年 | 6篇 |
2007年 | 8篇 |
2006年 | 6篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 7篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1997年 | 1篇 |
1991年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有112条查询结果,搜索用时 31 毫秒
101.
M. Ariza-Avidad M.P. Cuellar A. Salinas-Castillo M.C. Pegalajar J. Vuković L.F. Capitán-Vallvey 《Analytica chimica acta》2013
This study presents the development and characterization of a disposable optical tongue for the simultaneous identification and determination of the heavy metals Zn(II), Cu(II) and Ni(II). The immobilization of two chromogenic reagents, 1-(2-pyridylazo)-2-naphthol and Zincon, and their arrangement forms an array of membranes that work by complexation through a co-extraction equilibrium, producing distinct changes in color in the presence of heavy metals. The color is measured from the image of the tongue acquired by a scanner working in transmission mode using the H parameter (hue) of the HSV color space, which affords robust and precise measurements. The use of artificial neural networks (ANNs) in a two-stage approach based on color parameters, the H feature of the array, makes it possible to identify and determine the analytes. In the first stage, the metals present above a threshold of 10−7 M are identified with 96% success, regardless of the number of metals present, using the H feature of the two membranes. The second stage reuses the H features in combination with the results of the classification procedure to estimate the concentration of each analyte in the solution with acceptable error. Statistical tests were applied to validate the model over real data, showing a high correlation between the reference and predicted heavy metal ion concentration. 相似文献
102.
Mariela E. Sola Horacio G. Rotstein Julio C. Bazán 《Journal of Solid State Electrochemistry》2002,6(4):279-283
The time response of a Ag(s)/AgI(s)/graphite(s), I2(g) galvanic cell as iodine sensor was studied using both pure AgI and CsI doped AgI as electrolyte. The use of doped silver
iodide expanded considerably the working temperature. An analytical modeling of the sensor response is presented.
Electronic Publication 相似文献
103.
Mariana A. Vieira Patricia Grinberg Cláudio R.R. Bobeda Mariela N.M. Reyes Reinaldo C. Campos 《Spectrochimica Acta Part B: Atomic Spectroscopy》2009
In recent years, knowledge of the different chemical forms of the elements has gained increasing importance. There has been significant progress in methods that hyphenate chromatographic separations with atomic spectrometry. These hyphenated methods can provide the most complete information on the species distribution and even structure. However, they can be lengthy, relatively costly and difficult to bring to the routine. On the other hand, it is important to remember that chromatographic techniques represent only a minor part of the separation procedures available and, in certain cases, the application of basic chemistry to sample treatments can give quantitative information about specific chemical forms. In this sense, non-chromatographic procedures can provide methods that offer sufficient information on the elemental speciation for a series of situations. Moreover, these non-chromatographic strategies can be less time consuming, more cost effective and available, and present competitive limits of detection. Thus, non-chromatographic speciation analysis continues to be a promising research area and has been applied to the development of several methodologies that facilitate this type of analytical approach. In view of their importance, the present work overviews and discusses different non-chromatographic methods as alternatives for the speciation analysis of clinical, environmental and food samples using atomic spectrometry for detection. 相似文献
104.
Vaz PD Nolasco M Fonseca N Amado AM Costa AM Félix V Drew MG Goodfellow BJ Ribeiro-Claro PJ 《Physical chemistry chemical physics : PCCP》2005,7(16):3027-3034
The crystal structure of 4-phenyl-benzaldehyde reveals the presence of a dimer linked by the C=O and C9-H groups of adjacent molecules. In the liquid phase, the presence of C-H...O bonded forms is revealed by both vibrational and NMR spectroscopy. A DeltaH value of -8.2 +/- 0.5 kJ mol(-1) for the dimerisation equilibrium is established from the temperature-dependent intensities of the bands assigned to the carbonyl-stretching modes. The NMR data suggest the preferential engagement of the C(2,6)-H and C(10/12)/C(11)-H groups as hydrogen bond donors, instead of the C(9)-H group. While ab initio calculations for the isolated dimers are unable to corroborate these NMR results, the radial distribution functions obtained from molecular dynamics simulations show a preference for C(2,6)-H and C(10/12)/C(11)-H...O contacts relative to the C(9)-H...O ones. 相似文献
105.
Capillary rise experiments were performed in columns filled with glass beads and Berea sandstones, using visual methods to register the advance of the water front. For the glass bead filled columns, early time data are well fitted by the Washburn equation. However, in the experiments, the advancing front exceeded the predicted equilibrium height. For large times, an algebraic behavior of the velocity of the front is observed (T. Delker et al., Phys. Rev. Lett. 76, 2902 (1996)). A model for studying the capillary pressure evolution in a regular assembly of spheres is proposed and developed. It is based on a quasi-static advance of the meniscus with a piston-like motion and allows us to estimate the hydraulic equilibrium height, with values very close to those obtained by fitting early time data to a Washburn equation. The change of regime is explained as a transition in the mechanism of advance of the meniscus. On the other hand, only the Washburn regime was observed for the sandstones. The front velocity was fitted to an algebraical form with an exponent close to 0.5, a value expected from the asymptotic limit of the Washburn equation. Copyright 2001 Academic Press. 相似文献
106.
Vaz PD Nunes CD Vasconcellos-Dias M Nolasco MM Ribeiro-Claro PJ Calhorda MJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(28):7874-7882
Organic-inorganic mesoporous materials of the MCM-41 type are important materials that can be prepared by either post-synthesis or one-pot synthesis procedures. A complete control of the characteristics at a local level is of the utmost importance in view of the applications of such materials. However, there are not many studies relating such features with synthetic approaches. In this work, we prepared samples by post-synthesis derivatization of materials from Si-based MCM-41, with bidentate nitrogen ligands bearing one or two silylated arms, and by one-pot synthesis of organic-inorganic hybrid materials. The bulk properties of the two kinds of materials were comparable. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and Raman spectroscopy were used to investigate the local environment, namely, the number of OH groups and distribution of SiO(4) units (large and small ring units). Hydrophilicity correlates with both the type of organic moiety used (mono- or disilylated), as well as with the synthetic procedure. The same vibrational studies showed how the structure in the channels changes as a function of pressure, reflecting the low mechanical stability of the mesoporous materials. 相似文献
107.
108.
In this paper we solve an infinite-horizon linear quadratic control problem for a class of differential equations with countably infinite Markov jumps and multiplicative noise. The global solvability of the associated differential Riccati-type equations is studied under detectability hypotheses. A nonstochastic, operatorial approach is used. Some properties of the linear stochastic systems, such as stability, stabilizability and detectability, are also discussed on the basis of a new solution representation result. A generalized Ito's formula which applies to infinite dimensional stochastic differential equations with countably infinite Markov jumps is also provided. 相似文献
109.
We give examples of real Banach spaces with exactly infinite countably many complex structures and with ω1 many complex structures. 相似文献
110.
A Trifluorinated Thiazoline Scaffold Leading to Pro‐apoptotic Agents Targeting Prohibitins
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Alba Pérez‐Perarnau Dr. Sara Preciado Dr. Claudia Mariela Palmeri Cristina Moncunill‐Massaguer Dr. Daniel Iglesias‐Serret Dr. Diana M. González‐Gironès Dr. Miriam Miguel Dr. Satoki Karasawa Dr. Satoshi Sakamoto Dr. Ana M. Cosialls Dr. Camila Rubio‐Patiño José Saura‐Esteller Dr. Rosario Ramón Dr. Laia Caja Dr. Isabel Fabregat Dr. Gabriel Pons Prof. Hiroshi Handa Prof. Fernando Albericio Prof. Joan Gil Prof. Rodolfo Lavilla 《Angewandte Chemie (International ed. in English)》2014,53(38):10150-10154
A new class of small molecules, with an unprecedented trifluorothiazoline scaffold, were synthesized and their pro‐apoptotic activity was evaluated. With an EC50 in the low micromolar range, these compounds proved to be potent inducers of apoptosis in a broad spectrum of tumor cell lines, regardless of the functional status of p53. Fast structure–activity relationship studies allowed the preparation of the strongest apoptosis‐inducing candidate. Using a high performance affinity purification approach, we identified prohibitins 1 and 2, key proteins involved in the maintenance of cell viability, as the targets for these compounds. 相似文献