全文获取类型
收费全文 | 1435篇 |
免费 | 47篇 |
国内免费 | 6篇 |
专业分类
化学 | 925篇 |
力学 | 39篇 |
数学 | 332篇 |
物理学 | 192篇 |
出版年
2022年 | 9篇 |
2021年 | 14篇 |
2020年 | 8篇 |
2019年 | 22篇 |
2018年 | 16篇 |
2017年 | 16篇 |
2016年 | 35篇 |
2015年 | 40篇 |
2014年 | 40篇 |
2013年 | 98篇 |
2012年 | 95篇 |
2011年 | 123篇 |
2010年 | 69篇 |
2009年 | 65篇 |
2008年 | 113篇 |
2007年 | 84篇 |
2006年 | 79篇 |
2005年 | 74篇 |
2004年 | 86篇 |
2003年 | 45篇 |
2002年 | 51篇 |
2001年 | 20篇 |
2000年 | 21篇 |
1999年 | 19篇 |
1998年 | 17篇 |
1997年 | 10篇 |
1996年 | 14篇 |
1995年 | 12篇 |
1994年 | 14篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1985年 | 8篇 |
1984年 | 13篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1978年 | 17篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1973年 | 6篇 |
1971年 | 5篇 |
1936年 | 3篇 |
排序方式: 共有1488条查询结果,搜索用时 15 毫秒
151.
Sur les fonctions absolument monotones 总被引:2,自引:0,他引:2
Serge Bernstein 《Acta Mathematica》1929,52(1):1-66
152.
Bertrand Reuillard Solène Gentil Marie Carrière Alan Le Goff Serge Cosnier 《Chemical science》2015,6(9):5139-5143
We report the non-covalent functionalization of a multi-walled carbon nanotube (MWCNT) electrode with a biomimetic model of the horseradish peroxidase (HRP) active site. By modifying the MWCNT electrode surface with imidazole-modified polypyrrole, a new biomimetic complex of HRP was synthesized on the MWCNT sidewalls via the coordination of imidazole (Im) to the metal centre of iron protoporphyrin IX, affording (Im)(PP)FeIII. Compared to the pi-stacking of non-coordinated (PP)FeIII on a MWCNT electrode, the (Im)(PP)FeIII-modified MWCNT electrode exhibits higher electrocatalytic activity with an I max = 0.52 mA cm–2 for the reduction of H2O2, accompanied by a high onset potential of 0.43 V vs. Ag/AgCl. The performances of these novel surface-confined HRP mimics were compared to those of a MWCNT electrode modified by HRP. Although the enzyme electrode displays a higher electrocatalytic activity towards H2O2 reduction, the (Im)(PP)FeIII-modified MWCNT electrode exhibits a markedly higher operational stability, retaining 63% of its initial activity after one month. 相似文献
153.
Cristina Díez Davy Guillarme Aline Staub Spörri Emmanuelle Cognard Didier Ortelli Patrick Edder Serge Rudaz 《Analytica chimica acta》2015
In this study, fourteen highly polar aminoglycoside (AGs) antibiotics were selected. Various stationary phases were tested, including Obelisc R, ZIC-HILIC, BEH amide and aminopropyl. The nature of the stationary phase, mobile phase (water or buffer solutions and acetonitrile), pH (percentage of formic acid), gradient conditions and injection solvents were systematically studied as relevant parameters for tuning retention selectivity and detectability of AGs in liquid chromatography electrospray tandem mass spectrometry (LC–(ESI)–MS/MS). Only the two zwitterionic phases (Obelisc R and ZIC-HILIC) achieved a proper chromatographic separation considering interferences due to the crosstalk effect in low resolution mass spectrometers. The water/acetonitrile mobile phase containing 1% formic acid used with Obelisc R provided more sensitivity than the highly concentrated buffered mobile phases required for ZIC-HILIC. A solid phase extraction (SPE) clean-up procedure with polymeric weak cation exchange (WCX) cartridges was optimized for honey, milk and liver samples. Different brands of cartridges and elution solvents were tested, and the Taurus WCX offered the best recovery rate with a buffer elution at pH 3. The final optimized method was validated in these matrices according to Decision 2002/657/EC. A monitoring campaign for sixty honey, milk and liver samples was carried out at the Food Authority Control in Geneva. The concentration of dihydrostreptomycin (DSTP) found in one ovine liver exceeded the established maximum residue levels (MRLs) within the European and Swiss legislations but it was compliant taking into account the validation data. 相似文献
154.
An electrochemical biosensor capable of indirect detection of DNA damage induced by any one of the three endocrine-disrupting compounds (EDCs) – bisphenol A (BPA), 4-nonylphenol (NP) and 4-t-octylphenol (OP), has been researched and developed. The methylene blue (MB) dye was used as the redox indicator. The glassy carbon electrode (GCE) was modified by the assembled dsDNA/graphene oxide-chitosan/gold nano-particles to produce a dsDNA/GO-CS/AuNPs/GCE sensor. It was characterized with the use of electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and scanning electron microscopy (SEM) techniques. The loading/release of the MB dye by the dsDNA/GO-CS/AuNPs film was investigated, and the results showed that the process was reversible. Based on this, the sensor was used to measure the difference between the loading capabilities of intact and damaged dsDNA in the films. The sensor was then successfully applied to detect DNA damage electrochemically. The differential pulse voltammetry (DPV) peak current ratio for MB, observed before and after DNA damage, increased linearly in the presence the BPA, NP or OP compounds; the treatment range was 10–60 min, and the respective damage rates were 0.0069, 0.0044 and 0.0031 min−1, respectively. These results were confirmed by the binding constants: 2.09 × 106 M−1 (BPA-DNA), 1.28 × 106 M−1 (NP-DNA) and 9.33 × 105 M−1 (OP-DNA), all of which were obtained with the use of differential pulse stripping voltammetry (DPSV). 相似文献
155.
Biofunctionalization of Polyoxometalates with DNA Primers,Their Use in the Polymerase Chain Reaction (PCR) and Electrochemical Detection of PCR Products
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Ahmed M. Debela Dr. Mayreli Ortiz Dr. Valerio Beni Prof. Serge Thorimbert Dr. Denis Lesage Prof. Richard B. Cole Prof. Ciara K. O'Sullivan Prof. Bernold Hasenknopf 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(49):17721-17727
The bioconjugation of polyoxometalates (POMs), which are inorganic metal oxido clusters, to DNA strands to obtain functional labeled DNA primers and their potential use in electrochemical detection have been investigated. Activated monooxoacylated polyoxotungstates [SiW11O39{Sn(CH2)2CO}]8? and [P2W17O61{Sn(CH2)2CO}]6? have been used to link to a 5′‐NH2 terminated 21‐mer DNA forward primer through amide coupling. The functionalized primer was characterized by using a battery of techniques, including electrophoresis, mass spectrometry, as well as IR and Raman spectroscopy. The functionality of the POM‐labeled primers was demonstrated through hybridization with a surface‐immobilized probe. Finally, the labeled primers were successfully used in the polymerase chain reaction (PCR) and the PCR products were characterized by using electrophoresis. 相似文献
156.
A function on an algebra is congruence preserving if for any congruence, it maps congruent elements to congruent elements. We show that on a free monoid generated by at least three letters, a function from the free monoid into itself is congruence preserving if and only if it is of the form \({x \mapsto w_{0}xw_{1} \cdots w_{n-1}xw_n }\) for some finite sequence of words \({w_0,\ldots ,w_n}\). We generalize this result to functions of arbitrary arity. This shows that a free monoid with at least three generators is a (noncommutative) affine complete algebra. As far as we know, it is the first (nontrivial) case of a noncommutative affine complete algebra. 相似文献
157.
The authors show that for any e ∈]0,1[,there exists an analytic outside zero solution to a uniformly elliptic conformal Hessian equation in a ball B C R5 which belongs to C1'ε(B) \ C1'ε+(B). 相似文献
158.
A particle method has been used to simulate the vorticity transport in a two-dimensional flow of an incompressible inviscid fluid. In this method, not only the location and the circulation of the particle are used but also the moments of the internal vorticity. The transport equation for these moments has been derived from the vorticity transport equation. The method has been compared to the usual particle method as well as to Teng's elliptic vortex model. The test case is that of the evolution of two circular patches of vorticity already used by Teng. To cite this article: A. Beaudoin et al., C. R. Mecanique 330 (2002) 51–56 相似文献
159.
A rapid kinetic method for the simultaneous determination of levodopa, dopamine, and dobutamine was examined and developed.
It was based on a consecutive reaction of a reduction of Cu(II) to Cu(I) by catecholamines, followed by the complexation of
Cu(I) with neocuproine to form a yellow product in an acetic acid-acetate buffer. Spectrophotometric data were recorded at
453 nm (wavelength at the yellow complex absorption maximum) for 300 s. Linear calibrations were obtained in the concentration
ranges of (0.08–1.44) × 10−5 mol L−1, (0.08–1.44) × 10−5 mol L−1, and (0.16–1.44) × 10−5 mol L−1 for levodopa, dopamine, and dobutamine, respectively. A variety of multivariate calibration models was developed for simultaneous
analysis of the three analytes; while most models produced satisfactory prediction results for synthetic samples, the hybrid
linear analysis method was arguably the best-performing (relative prediction error, RPET = 6.6 %). The proposed method was
applied to an analysis of spiked rabbit serum samples and the results showed good agreement with the high performance liquid
chromatography measurements. 相似文献
160.
This tutorial review briefly surveys the chronological evolution of biosensor concepts based on electrogenerated polymers. The most common procedures of biomolecule immobilization are classified as direct electropolymerization, physical entrapment, covalent linkage, and anchoring by affinity interactions via electropolymerized films. These are discussed, and recent bioanalytical applications are described. The discussion emphasizes the use of templates for controlling the formation of nanowires and composite polymers. Recent advances in the design of three-dimensional biological architectures are also highlighted. 相似文献