全文获取类型
收费全文 | 212篇 |
免费 | 3篇 |
国内免费 | 1篇 |
专业分类
化学 | 143篇 |
力学 | 5篇 |
数学 | 13篇 |
物理学 | 55篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2020年 | 4篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 5篇 |
2014年 | 7篇 |
2013年 | 6篇 |
2012年 | 27篇 |
2011年 | 3篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 9篇 |
2007年 | 8篇 |
2006年 | 17篇 |
2005年 | 8篇 |
2004年 | 9篇 |
2003年 | 4篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 9篇 |
1999年 | 1篇 |
1998年 | 8篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1949年 | 2篇 |
1948年 | 1篇 |
1947年 | 5篇 |
1938年 | 1篇 |
1933年 | 1篇 |
排序方式: 共有216条查询结果,搜索用时 15 毫秒
91.
92.
93.
A method for the estimation of gallium in bauxites and derived products, has been described. The gallium is estimated fluorimetrically in chloroform solution as the oxmate. The interfering ions and the means of their removal have been studied.The method allows the estimation of 1.4–4.2 γ of gallium with an accuracy of about 10%. 相似文献
94.
Avik Khan Tanzina Huq Ruhul A. Khan Dominic Dussault Stephane Salmieri Monique Lacroix 《Radiation Physics and Chemistry》2012,81(8):941-944
Chitosan films were prepared by dissolving 1% (w/v) chitosan powder in 2% (w/v) aqueous acetic acid solution. Chitosan films were prepared by solution casting. The values of puncture strength (PS), viscoelasticity coefficient and water vapor permeability (WVP) of the films were found to be 565 N/mm, 35%, and 3.30 g mm/m2 day kPa, respectively. Chitosan solution was exposed to gamma irradiation (0.1–5 kGy) and it was revealed that PS values were reduced significantly (p≤0.05) after 1 kGy dose and it was not possible to form films after 5 kGy. Monomer, 2-hydroxyethyl methacrylate (HEMA) solution (0.1–1%, w/v) was incorporated into the chitosan solution and the formulation was exposed to gamma irradiation (0.3 kGy). A 0.1% (w/v) HEMA concentration at 0.3 kGy dose was found optimal-based on PS values for chitosan grafting. Then radiation dose (0.1–5 kGy) was optimized for HEMA grafting. The highest PS values (672 N/mm) were found at 0.7 kGy. The WVP of the grafted films improved significantly (p≤0.05) with the rise of radiation dose. 相似文献
95.
Jalal Ghilane Pascal Martin Marion Janin Hyacinthe Randriamahazaka Philippe Hapiot Jean-Christophe Lacroix 《Electrochemistry communications》2009,11(12):2304-2307
Thin layer of conducting polymer, poly(3,4-ethylenedioxythiophene) PEDOT, deposited on insulating substrates was electrochemically investigated. This study was performed through the reaction with a series of electrogenerated mediators at a microelectrode operating in the configuration of a scanning electrochemical microscope (SECM). The method proves to be a convenient tool for investigating redox properties of the electroactive materials onto insulating substrate and the occurrence of electron transfers across the modified substrate. The SECM results demonstrate the possibility of the regeneration of the mediator at the modified surface even if the used substrate is an insulator. The regeneration rate depends on the standard redox potential of the mediator, on the switching potential of the polymer and on its initial oxidation state. In addition, the obtained data could be analyzed through the construction of the steady state voltammograms allowing the extraction of the electrochemical properties of the thin organic layer deposited onto insulating surface. 相似文献
96.
Marion Janin Jalal Ghilane Hyacinthe Randriamahazaka Jean-Christophe Lacroix 《Electrochemistry communications》2009,11(3):647-650
This work is devoted to the study of the electrochemical grafting of nitrophenyl groups onto platinum ultramicroelectrode (UME). The grafting was made using the electrochemical reduction of nitrophenyldiazonium. Our results demonstrate the possibility to reduce the diazonium onto Pt UME. As consequence the electrochemical reduction leads to the attachment of nitrophenyl groups onto the UME surface. Following that, the modified UME was characterized using electrochemical techniques. In addition, the electrochemical response of the modified UME in the presence of reversible redox couple, ferrocene, has been studied. The main remark is that the steady state current observed at the UME is not affected by the presence of the nitrophenyl layers. Finally, from this last point we demonstrate the possibility to achieve scanning electrochemical microscopy (SECM) using modified platinum UME. 相似文献
97.
After surveying the known connections between topological entropy zero and nonexistence of certain types of pairs in the system, we supplement them by showing that a topological dynamical system has topological entropy zero if and only if it is a factor of a system with no forward mean asymptotic pairs. This covers two former statements of [O-W] and [D-L]. 相似文献
98.
Let T be a continuous map on a compact metric space (X, d). A pair of distinct points x, y ∈ X is asymptotic if lim n→∞ d(T n x, T n y) = 0. We prove the following four conditions to be equivalent: 1. h top(T) = 0; 2. (X, T) has a (topological) extension (Y,S) which has no asymptotic pairs; 3. (X, T) has a topological extension (Y ′, S′) via a factor map that collapses all asymptotic pairs; 4. (X, T) has a symbolic extension (i.e., with (Y ′, S′) being a subshift) via a map that collapses asymptotic pairs. The maximal factors (of a given system (X, T)) corresponding to the above properties do not need to coincide. 相似文献
99.
Bourdoncle A Estévez Torres A Gosse C Lacroix L Vekhoff P Le Saux T Jullien L Mergny JL 《Journal of the American Chemical Society》2006,128(34):11094-11105
Molecular beacons (MBs) are fluorescent nucleic acid probes with a hairpin-shaped structure in which the 5' and 3' ends are self-complementary. Due to a change in their emissive properties upon recognition with complementary sequences, MBs allow the diagnosis of single-stranded DNA or RNA with high mismatch discrimination, in vitro and in vivo. Whereas the stems of MB hairpins usually rely on the formation of a Watson-Crick duplex, we demonstrate in this report that the preceding structure can be replaced by a G-quadruplex motif (G4). Intramolecular quadruplexes may still be formed with a central loop composed of 12 to 21 bases, therefore extending the sequence repertoire of quadruplex formation. G4-MB can efficiently be used for oligonucleotide discrimination: in the presence of a complementary sequence, the central loop hybridizes and forms a duplex that causes opening of the quadruplex stem. The corresponding G4-MB unfolding can be detected by a change in its fluorescence emission. We discuss the thermodynamic and kinetic opportunities that are provided by using G4-MB instead of traditional MB. In particular, the intrinsic feature of the quadruplex motif facilitates the design of functional molecular beacons by independently varying the concentration of monovalent or divalent cations in the medium. 相似文献
100.