全文获取类型
收费全文 | 1148篇 |
免费 | 31篇 |
国内免费 | 11篇 |
专业分类
化学 | 737篇 |
晶体学 | 6篇 |
力学 | 34篇 |
数学 | 241篇 |
物理学 | 172篇 |
出版年
2023年 | 6篇 |
2022年 | 15篇 |
2021年 | 21篇 |
2020年 | 18篇 |
2019年 | 10篇 |
2018年 | 21篇 |
2017年 | 13篇 |
2016年 | 40篇 |
2015年 | 27篇 |
2014年 | 21篇 |
2013年 | 47篇 |
2012年 | 71篇 |
2011年 | 75篇 |
2010年 | 50篇 |
2009年 | 40篇 |
2008年 | 61篇 |
2007年 | 71篇 |
2006年 | 61篇 |
2005年 | 45篇 |
2004年 | 34篇 |
2003年 | 33篇 |
2002年 | 42篇 |
2001年 | 10篇 |
2000年 | 13篇 |
1999年 | 15篇 |
1998年 | 13篇 |
1997年 | 6篇 |
1996年 | 13篇 |
1995年 | 14篇 |
1994年 | 17篇 |
1993年 | 7篇 |
1992年 | 10篇 |
1991年 | 13篇 |
1990年 | 14篇 |
1989年 | 8篇 |
1988年 | 9篇 |
1987年 | 14篇 |
1986年 | 18篇 |
1985年 | 17篇 |
1984年 | 25篇 |
1983年 | 21篇 |
1982年 | 15篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 13篇 |
1978年 | 5篇 |
1976年 | 10篇 |
1975年 | 5篇 |
1972年 | 3篇 |
1933年 | 3篇 |
排序方式: 共有1190条查询结果,搜索用时 46 毫秒
111.
Destabilization of liquid film by electro-hydro-dynamics (EHD) pressure is achieved through the pyroelectric effect on a polar dielectric crystal. We show that by destabilizing the liquid film, periodical self-assembled multi-jets are obtained. The multi-jets operate simultaneously and could be exploited to dispense liquids with nanolitre drops. Such multiple self-assembled liquid jets have significant potential applicability for high-throughput liquid transfer by this novel pyro-EHD ink-jet approach. Since the method avoids the use of nozzles and electrodes, it is especially suitable for highly viscous liquids. Here we present and discuss the new multi-jet process and the results obtained with a liquid polymer (PDMS). 相似文献
112.
Pietro Caputo Fabio Martinelli François Simenhaus Fabio Lucio Toninelli 《纯数学与应用数学通讯》2011,64(6):778-831
We consider the Glauber dynamics for the Ising model with “+” boundary conditions, at zero temperature or at a temperature that goes to zero with the system size (hence the quotation marks in the title). In dimension d = 3 we prove that an initial domain of linear size L of “−” spins disappears within a time τ+, which is at most L2(log L)c and at least L2/(c log L) for some c > 0. The proof of the upper bound proceeds via comparison with an auxiliary dynamics which mimics the motion by mean curvature that is expected to describe, on large time scales, the evolution of the interface between “+” and “−” domains. The analysis of the auxiliary dynamics requires recent results on the fluctuations of the height function associated to dimmer coverings of the infinite honeycomb lattice. Our result, apart from the spurious logarithmic factors, is the first rigorous confirmation of the Lifshitz law τ+ ≃ const × L2, conjectured on heuristic grounds [8, 13]. In dimension d = 2, τ+ can be shown to be of order L2 without logarithmic corrections: the upper bound was proven in [6], and here we provide the lower bound. For d = 2, we also prove that the spectral gap of the generator behaves like for L large, as conjectured in [2]. © 2011 Wiley Periodicals, Inc. 相似文献
113.
Arfè Andrea Peluso Stefano Muliere Pietro 《Statistical Inference for Stochastic Processes》2021,24(1):1-15
The literature on Bayesian methods for the analysis of discrete-time semi-Markov processes is sparse. In this paper, we introduce the semi-Markov beta-Stacy process, a stochastic process useful for the Bayesian non-parametric analysis of semi-Markov processes. The semi-Markov beta-Stacy process is conjugate with respect to data generated by a semi-Markov process, a property which makes it easy to obtain probabilistic forecasts. Its predictive distributions are characterized by a reinforced random walk on a system of urns.
相似文献114.
Assunta Esposito Pietro Filippo De Luca Vittoria Graziani Brigida DAbrosca Antonio Fiorentino Monica Scognamiglio 《Molecules (Basel, Switzerland)》2021,26(13)
Olea europaea germplasm is constituted by a huge number of cultivars, each one characterized by specific features. In this context, endemic cultivars evolved for a very long period in a precise local area, developing very specific traits. These characteristics include the production and accumulation of phytochemicals, many of which are also responsible for the nutraceutical value of the drupes and of the oils therefrom. With the aim of obtaining information on the phytochemical profile of drupes of autochthonous cultivars of Cilento, Vallo di Diano and Alburni National Park, a metabolomics-based study was carried out on 19 selected cultivars. Multivariate data analysis of 1H-NMR data and 2D NMR analyses allowed the rapid identification of metabolites that were qualitatively and/or quantitatively varying among the cultivars. This study allowed to identify the cultivars Racioppella, Guglia, Pizzulella, Oliva amara, and Racioppa as the richest in health-promoting phenolic compounds. Furthermore, it showed a significant variability among the different cultivars, suggesting the possibility of using metabolic fingerprinting approaches for cultivar differentiation, once that further studies aimed at assessing the influence of growing conditions and environmental factors on the chemical profiles of single cultivars are carried out. 相似文献
115.
116.
Starting from the definitions and the properties of reinforced renewal processes and reinforced Markov renewal processes,
we characterize, via exchangeability and de Finetti’s representation theorem, a prior that consists of a family of Dirichlet
distributions on the space of Markov transition matrices and beta-Stacy processes on distribution functions. Then, we show
that this family is conjugate and give some estimate results.
相似文献
相似文献
117.
118.
Pietro Favia Victor H. Perez-Luna Thomas Boland David G. Castner Buddy D. Ratner 《Plasmas and Polymers》1996,1(4):299-326
Fluoropolymer films have been deposited in the glow and afterglow regions of radio frequency glow discharges fed with C2F6−H2 mixtures. Structure, growth rate, composition, and wettability of the films have been investigated by means of atomic force
microscopy, electron spectroscopy for chemical analysis, secondary ion mass spectrometry, and water contact angle measurements.125I labeled baboon fibrinogen in baboon plasma has been used to study the adsorption of the protein onto the films. Protein
retention, i.e., the binding affinity of the adsorbed protein, has been examined by elution with a sodium dodecyl sulfate
solution. Adsorption and retention of fibrinogen were correlated using multivariate statistical methods with the wettability,
the degree of film fluorination, and the CF
x
(1≤x≤3) group distribution of the coatings. This correlation identified the influence of each variable on the adsorption and retention
of fibrinogen onto these substrates. These variables or surface properties can be easily balanced by properly tuning the experimental
conditions of the glow discharge deposition process. 相似文献
119.
Domenico Alfieri Giuseppe Coppola Pietro Ferraro Giovanni Pierattini 《Optics Communications》2006,260(1):113-116
A method for allowing direct perfect superimposition and comparison of Fresnel-transform reconstructions of digital holograms recorded of the same object at different distances and wavelengths is proposed and demonstrated. The method takes into account the dependence of the reconstruction pixel on the distance and the wavelength by the Fresnel-transform algorithm. The method avoids the need for image scaling at the end of the reconstruction process that usually is performed in multi-wavelength digital holography. Demonstration is given by superposing the numerical reconstructions of holograms recorded at different distances and wavelengths. The method can be potentially very useful for real-time monitoring in biological processes or for recognition and ranging by multiple wavelengths of a target with fast movements or finally for very fast investigation and study of very fast processes. 相似文献
120.
Andrea Cappelli Maurizio Anzini Salvatore Vomero Alessandro Donati Lucia Zetta Raniero Mendichi Mario Casolaro Pietro Lupetti Paolo Salvatici Gianluca Giorgi 《Journal of polymer science. Part A, Polymer chemistry》2005,43(15):3289-3304
The macromolecular and aggregate structures of poly[ethyl 1‐methylene‐3‐(4‐methylphenyl)‐1H‐indene‐2‐carboxylate] (poly‐ BF1 ; a new polymer based on a functionalized benzofulvene moiety showing interesting properties, i.e., thermoreversible polymerization/depolymerization behavior, high solubility in the most common organic solvents, and susceptibility to molecular manipulation) have been investigated with NMR spectroscopy, absorption and emission spectrophotometry, and transmission electron microscopy (TEM). Moreover, the polymerization mechanism has been studied to obtain further information on the polymer structure. The collected evidence is consistent in indicating for poly‐ BF1 a vinyl (1,2) polymer structure stabilized by means of aromatic stacking interactions. Furthermore, TEM studies performed on metal replicas have shown that the polymer is liable to give nanostructured aggregates. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3289–3304, 2005 相似文献