全文获取类型
收费全文 | 237篇 |
免费 | 6篇 |
专业分类
化学 | 197篇 |
晶体学 | 2篇 |
力学 | 2篇 |
数学 | 9篇 |
物理学 | 33篇 |
出版年
2021年 | 1篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 3篇 |
2013年 | 7篇 |
2012年 | 8篇 |
2011年 | 8篇 |
2010年 | 7篇 |
2009年 | 6篇 |
2008年 | 9篇 |
2007年 | 4篇 |
2006年 | 9篇 |
2005年 | 13篇 |
2004年 | 11篇 |
2003年 | 8篇 |
2002年 | 15篇 |
2001年 | 3篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 8篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1964年 | 2篇 |
1952年 | 1篇 |
1938年 | 1篇 |
1931年 | 1篇 |
排序方式: 共有243条查询结果,搜索用时 9 毫秒
41.
Henriette de Loor Ruben Poesen Wout De Leger Wim Dehaen Patrick Augustijns Pieter Evenepoel Björn Meijers 《Analytica chimica acta》2016
Chronic kidney disease (CKD) is associated with an increased risk of mortality and cardiovascular disease, which is, at least partly, mediated by the accumulation of so-called uremic retention solutes. Although there has been an increasing interest in the behavior of these solutes, derived from both the endogenous and colonic microbial metabolism, methods to simultaneously and accurately measure a broad panel of relevant uremic retention solutes remain scarce. 相似文献
42.
Wolpher H Sinha S Pan J Johansson A Lundqvist MJ Persson P Lomoth R Bergquist J Sun L Sundström V Akermark B Polívka T 《Inorganic chemistry》2007,46(3):638-651
A series of bis(terpyridine)RuII complexes have been prepared, where one of the terpyridines is functionalized in the 4'-position by a phosphonic or carboxylic acid group for attachment to TiO2. The other is functionalized, also in the 4'-position, by a potential electron donor. In complexes 1a, 3a, and 4a,b, this donor is tyrosine or hydrogen-bonded tyrosine, while in 2a it is carotenoic amide. The synthesis and photophysical properties of the complexes are discussed. On irradiation with visible light, the formation of a long-lived charge-separated state was anticipated, via primary electron ejection into the TiO2, followed by secondary electron transfer from the donor to the photogenerated RuIII. However, such a charge-separated state could be observed with certainty only with complex 2a. To explain the result, quantum chemical calculations were performed on the different types of complexes. 相似文献
43.
Jensen MH Morris EJ Simonsen AC 《Langmuir : the ACS journal of surfaces and colloids》2007,23(15):8135-8141
A number of morphological and statistical aspects of domain formation in singly and doubly supported ternary membranes have been investigated. Such ternary membranes produce macroscopic phase separation in two fluid phases and are widely used as raft models. We find that membrane interactions with the support surface can have a critical influence on the domain shapes if measures are not taken to screen these interactions. Combined AFM and fluorescence microscopy demonstrate small (500 nm) irregular domains and incomplete formation of much larger (5 microm) round domains. These kinetically trapped structures are the result of interactions between the membrane and the support surface, and they can be effectively removed by employing doubly supported membranes under physiological salt concentrations. These decoupled supported membranes display macroscopic round domains that are easily perturbed by fluid shear flow. The system allows a quantitative characterization of domain coarsening upon being cooled into the coexistence region. We determine the domain growth exponent alpha = 0.31, which is in close agreement with the theoretical value of 1/3. Analysis of the spatial domain pattern in terms of Voronoi polygons demonstrates a close similarity to equilibrated cellular structures with a maximized configurational entropy. 相似文献
44.
We study the quantification of signal strength in wavelength-modulation spectroscopy, and present algorithms which allow for
the quantitative analysis of second-harmonic spectra for arbitrary combinations of line width and modulation depth. The algorithms
are validated through measurements on CO lines in the 0 ? 3 overtone band. They can be used for measuring the line strength
of lines that are too weak to allow direct absorbance measurements, and for quantifying the response from monitors applying
wavelength-modulation under conditions where calibration with certified gases is not feasible.
Received: 20 August 1999 / Revised version: 2 September 1999 / Published online: 30 November 1999 相似文献
45.
46.
47.
The interaction between a semi-large aromatic hydrocarbon compound (perylene) and the TiO2(1 1 0)-(1 × 1) surface under ultra high vacuum conditions has been probed by X-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS) and near-edge X-ray absorption fine structure (NEXAFS) methods. UPS measurements of the adsorbate system have been compared with an experimental UPS spectrum of perylene in the gas phase and a calculated spectrum obtained by means of density functional theory (DFT) methods. NEXAFS results of perylene molecules adsorbed on TiO2(1 1 0)-(1 × 1) were compared with data from an α-phase perylene single crystal. A novel analysis of the valence data has been employed to show that no strong chemical interaction takes place between perylene and the TiO2(1 1 0)-(1 × 1) surface. Furthermore, angle-dependent NEXAFS measurements and the growth curve results suggest that the perylene molecules are oriented flat down onto the TiO2 substrate due to weak van der Waals interactions. 相似文献
48.
V. L. E. Simonsen L. Nørskov A. Hagen K. Kammer Hansen 《Journal of Solid State Electrochemistry》2009,13(10):1529-1534
The series La2 − x
Sr
x
NiO4 (x = 0.0, 0.05, 0.15, 0.25, 0.35, and 1.0) was tested for functionality as electrode materials for direct electrochemical reduction
of NO. The materials were tested using cyclic voltammetry in 1% NO and 10% O2 in Ar on a cone-shaped electrode. The best materials for the electrochemical reduction of NO are La2NiO4 and LaSrNiO4, which have current densities for NO reduction 1.82 and 7.09 times higher, respectively, than for O2 at 400 °C. Increasing the temperature decreased the ability to reduce NO before O2 while the activity increased. The adsorbed species during direct decomposition was attempted, clarified using X-ray absorption
near-edge structure experiments and thermogravimetry, but no conclusive results were obtained. 相似文献
49.
Boere IA Robinson DJ de Bruijn HS Kluin J Tilanus HW Sterenborg HJ de Bruin RW 《Photochemistry and photobiology》2006,82(6):1638-1644
Barrett's esophagus (BE) can experimentally be treated with 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT), in which ALA, the precursor of the endogenous photosensitizer protoporphyrin IX (PpIX) and subsequent irradiation with laser light are applied to destroy the (pre)malignant tissue. Accurate dosimetry is critical for successful ALA-PDT. Here, in vivo dosimetry and kinetics of PpIX fluorescence photobleaching were studied in a rat model of BE. The fluence and fluence rate were standardized in vivo and PpIX fluorescence was measured simultaneously at the esophageal wall during ALA-PDT and plotted against the delivered fluence rather than time. Rats with BE were administered 200 mg kg(-1) ALA (n = 17) or served as control (n = 4). Animals were irradiated with 633 nm laser light at a measured fluence rate of 75 mW cm(-2) and a fluence of 54 J cm(-2). Large differences were observed in the kinetics of PpIX fluorescence photobleaching in different animals. High PpIX fluorescence photobleaching rates corresponded with tissue ablation, whereas low rates corresponded with no damage to the epithelium. Attempts to influence tissue oxygenation by varying balloon pressure and ventilation were shown not to be directly responsible for the differences in effect. In conclusion, in vivo dosimetry is feasible in heterogeneous conditions such as BE, and PpIX fluorescence photobleaching is useful to predict the tissue response to ALA-PDT. 相似文献
50.
The synthesis of substituted 2-cyanoarylboronic esters is described via lithiation/in situ trapping of the corresponding methoxy-, trifluoromethyl-, fluoro-, chloro-, and bromobenzonitriles. The crude arylboronic esters were obtained in high yields and purities and with good regioselectivities. 相似文献