全文获取类型
收费全文 | 226篇 |
免费 | 3篇 |
国内免费 | 2篇 |
专业分类
化学 | 132篇 |
力学 | 28篇 |
数学 | 45篇 |
物理学 | 26篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 10篇 |
2015年 | 7篇 |
2014年 | 3篇 |
2013年 | 15篇 |
2012年 | 20篇 |
2011年 | 16篇 |
2010年 | 7篇 |
2009年 | 8篇 |
2008年 | 7篇 |
2007年 | 9篇 |
2006年 | 4篇 |
2005年 | 8篇 |
2004年 | 6篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2001年 | 7篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有231条查询结果,搜索用时 15 毫秒
41.
42.
Anna Szabó Rolando Pasquariello Pedro F. Costa Radmila Pavlovic Indi Geurs Koen Dewettinck Chris Vervaet Tiziana A. L. Brevini Fulvio Gandolfi Sandra Van Vlierberghe 《Macromolecular bioscience》2023,23(10):2300016
To provide prominent accessibility of fishmeal to the European population, the currently available, time- and cost-extensive feeding trials, which evaluate fish feed, should be replaced. The current paper reports on the development of a novel 3D culture platform, mimicking the microenvironment of the intestinal mucosa in vitro. The key requirements of the model include sufficient permeability for nutrients and medium-size marker molecules (equilibrium within 24 h), suitable mechanical properties (G' < 10 kPa), and close morphological similarity to the intestinal architecture. To enable processability with light-based 3D printing, a gelatin-methacryloyl-aminoethyl-methacrylate-based biomaterial ink is developed and combined with Tween 20 as porogen to ensure sufficient permeability. To assess the permeability properties of the hydrogels, a static diffusion setup is utilized, indicating that the hydrogel constructs are permeable for a medium size marker molecule (FITC-dextran 4 kg mol−1). Moreover, the mechanical evaluation through rheology evidence a physiologically relevant scaffold stiffness (G' = 4.83 ± 0.78 kPa). Digital light processing-based 3D printing of porogen-containing hydrogels results in the creation of constructs exhibiting a physiologically relevant microarchitecture as evidenced through cryo-scanning electron microscopy. Finally, the combination of the scaffolds with a novel rainbow trout (Oncorhynchus mykiss) intestinal epithelial cell line (RTdi-MI) evidence scaffold biocompatibility. 相似文献
43.
Fulvio Gesmundo Jonathan D. Hauenstein Christian Ikenmeyer J. M. Landsberg 《Foundations of Computational Mathematics》2016,16(3):599-635
We use algebraic geometry to study matrix rigidity and, more generally, the complexity of computing a matrix–vector product, continuing a study initiated in Kumar et al. (2009), Landsberg et al. (preprint). In particular, we (1) exhibit many non-obvious equations testing for (border) rigidity, (2) compute degrees of varieties associated with rigidity, (3) describe algebraic varieties associated with families of matrices that are expected to have super-linear rigidity, and (4) prove results about the ideals and degrees of cones that are of interest in their own right. 相似文献
44.
45.
Fulvio Cacace Giulia de Petris Federico Pepi Marzio Rosi Antonio Sgamellotti 《Angewandte Chemie (International ed. in English)》1999,38(16):2408-2410
Complexes that undergo extensive molecular reorganization upon unimolecular metastable dissociation are obtained after ionization of atmospheric gases containing ozone and chlorofluorocarbons [Eq. (1)]. These unusual processes, which require fission of all bonds initially present in the CHX2 unit (X=Cl, F) and combination of C with one of the O atoms of ozone, were demonstrated and their mechanism rationalized by the joint application of mass spectrometric and theoretical methods. 相似文献
46.
The motion tracking enhancement technique (MTE) is a recently introduced method to improve the accuracy of tomographic PIV
measurements at seeding density higher than currently practiced. The working principle is based on the fact that the particle
field and its projections are correlated between the two exposures. Therefore, information from subsequent exposures can be
shared within the tomographic reconstruction process of a single object, which largely reduces the energy lost into ghost particles. The study follows a previous work based on synthetic particle images, showing that the MTE technique has an effect similar
to that of increasing the number of cameras. In the present analysis, MTE is applied to Tomographic PIV data from two time-resolved
experiments on turbulent shear flows: a round jet at Re = 5,000 (f
acq = 1,000 Hz) and a turbulent boundary layer at the trailing edge of an airfoil (Re
c = 370,000) measured at 12,000 Hz. The application of MTE is extended to the case of more than two recordings. The performance
is assessed comparing the results from a lowered number of cameras with respect to the full tomographic imaging system. The
analysis of the jet flow agrees with the findings of numerical simulations provided the results are scaled taking into account the concept of MTE efficiency based on the volume fraction where ghost-pairs (Elsinga et al. 2010a) are produced. When a large fraction of fluid has uniform motion (stagnant fluid surrounding the jet), only a moderate reduction
in ghost intensity is expected by MTE. Nevertheless, a visible recovery of reconstruction quality is observed for the 3-cameras system when
MTE is applied making use of 3 recordings. In the turbulent boundary layer, the objective is set to increase the seeding density
beyond current practice, and the experiments are performed at approximately 200,000 particles/megapixel. The measurement robustness
is monitored with the signal-to-noise ratio S/N for the cross-correlation analysis. An estimate of the precision error is
obtained for the turbulent boundary layer case following the peak height of the spatio-temporal cross-correlation function
(frozen-turbulence). The MTE approach appears to be essential for the increase in robustness and measurement precision at such seeding density. 相似文献
47.
48.
The spectrum of a Gelfand pair of the form ${(K\ltimes N,K)}$ , where N is a nilpotent group, can be embedded in a Euclidean space ${{\mathbb R}^d}$ . The identification of the spherical transforms of K-invariant Schwartz functions on N with the restrictions to the spectrum of Schwartz functions on ${{\mathbb R}^d}$ has been proved already when N is a Heisenberg group and in the case where N?=?N 3,2 is the free two-step nilpotent Lie group with three generators, with K?=?SO3 (Astengo et?al. in J Funct Anal 251:772–791, 2007; Astengo et?al. in J Funct Anal 256:1565–1587, 2009; Fischer and Ricci in Ann Inst Fourier Gren 59:2143–2168, 2009). We prove that the same identification holds for all pairs in which the K-orbits in the centre of N are spheres. In the appendix, we produce bases of K-invariant polynomials on the Lie algebra ${{\mathfrak n}}$ of N for all Gelfand pairs ${(K\ltimes N,K)}$ in Vinberg’s list (Vinberg in Trans Moscow Math Soc 64:47–80, 2003; Yakimova in Transform Groups 11:305–335, 2006). 相似文献
49.
P. S. Ramanujam Christian Holme Sren Hvilsted Marianne Pedersen Fulvio Andruzzi Massimo Paci Eliana L. Tassi Pierluigi Magagnini Uwe Hoffman Ingo Zebger Heinz W. Siesler 《先进技术聚合物》1996,7(9):768-776
Azobenzene side-chain liquid crystalline polyester structures suitable for permanent optical storage are described. The synthesis and characterization of the polyesters together with differential scanning calorimetry and X-ray investigations are discussed. Optical anisotropic investigations and holographic storage in one particular polyester are described in detail and polarized Fourier transform infrared spectroscopic data complementing the optical data are presented. Optical and atomic force microscope investigations point to a laser-induced aggregation as responsible for permanent optical storage. 相似文献
50.
Rosalba Leuci Leonardo Brunetti Antonio Laghezza Luca Piemontese Antonio Carrieri Leonardo Pisani Paolo Tortorella Marco Catto Fulvio Loiodice 《Molecules (Basel, Switzerland)》2022,27(3)
A new series of aryloxyacetic acids was prepared and tested as peroxisome proliferator-activated receptors (PPARs) agonists and fatty acid amide hydrolase (FAAH) inhibitors. Some compounds exhibited an interesting dual activity that has been recently proposed as a new potential therapeutic strategy for the treatment of Alzheimer’s disease (AD). AD is a multifactorial pathology, hence multi-target agents are currently one of the main lines of research for the therapy and prevention of this disease. Given that cholinesterases represent one of the most common targets of recent research, we decided to also evaluate the effects of our compounds on the inhibition of these specific enzymes. Interestingly, two of these compounds, (S)-5 and 6, showed moderate activity against acetylcholinesterase (AChE) and even some activity, although at high concentration, against Aβ peptide aggregation, thus demonstrating, in agreement with the preliminary dockings carried out on the different targets, the feasibility of a simultaneous multi-target activity towards PPARs, FAAH, and AChE. As far as we know, these are the first examples of molecules endowed with this pharmacological profile that might represent a promising line of research for the identification of novel candidates for the treatment of AD. 相似文献