全文获取类型
收费全文 | 323篇 |
免费 | 18篇 |
国内免费 | 1篇 |
专业分类
化学 | 247篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 50篇 |
物理学 | 40篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 15篇 |
2020年 | 10篇 |
2019年 | 9篇 |
2018年 | 6篇 |
2017年 | 1篇 |
2016年 | 18篇 |
2015年 | 15篇 |
2014年 | 12篇 |
2013年 | 24篇 |
2012年 | 35篇 |
2011年 | 31篇 |
2010年 | 14篇 |
2009年 | 10篇 |
2008年 | 16篇 |
2007年 | 19篇 |
2006年 | 16篇 |
2005年 | 14篇 |
2004年 | 18篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有342条查询结果,搜索用时 78 毫秒
211.
212.
Sanchez LM Curtis ME Bracamonte BE Kurita KL Navarro G Sparkman OD Linington RG 《Organic letters》2011,13(15):3770-3773
Analysis of substrates directly on solid phase resins without the need for separate cleavage conditions remains an outstanding challenge in the field of solid phase synthesis. We now present the first example of simultaneous cleavage and mass spectrometric analysis of peptides from solid supports using direct analysis in real time (DART) mass spectrometry. We have shown that this method is compatible with a diverse array of solid phase resins and is suitable for analysis of both peptides and organic substrates. 相似文献
213.
214.
Bianca Borem Ferreira 《Chaos, solitons, and fractals》2011,44(8):587-599
The dynamics of cardiovascular rhythms have been widely studied due to the key aspects of the heart in the physiology of living beings. Cardiac rhythms can be either periodic or chaotic, being respectively related to normal and pathological physiological functioning. In this regard, chaos control methods may be useful to promote the stabilization of unstable periodic orbits using small perturbations. In this article, the extended time-delayed feedback control method is applied to a natural cardiac pacemaker described by a mathematical model. The model consists of a modified Van der Pol equation that reproduces the behavior of this pacemaker. Results show the ability of the chaos control strategy to control the system response performing either the stabilization of unstable periodic orbits or the suppression of chaotic response, avoiding behaviors associated with critical cardiac pathologies. 相似文献
215.
Claudia Simone Wagner Bianca Fischer Manuela May Alexander Wittemann 《Colloid and polymer science》2010,288(5):487-498
We report on the fabrication of colloidal clusters through the combination of spherical particles. Polystyrene latex particles
bearing amino groups on their surface were used as building blocks of the clusters. Packing of these particles with diameters
of 91 and 154 nm into assemblies with defined configurations was accomplished using narrow dispersed emulsion droplets as
templates. The building blocks of the clusters adhered to the oil–water interphase due to the Pickering effect. Subsequent
evaporation of the dispersed phase forced them to pack into small clusters. Addition of the particles via the dispersed phase
led to higher yields of clusters than if the building blocks were added via the continuous phase. All clusters had well-defined
configurations. Because the dimensions of these clusters were below 400 nm, the colloidal assemblies underlay Brownian motion,
which resulted in stable suspensions. The number and yields of different species could be controlled via the concentration
of the building blocks and surfactant within the emulsions. Moreover, the nature of the dispersed phase itself had a strong
impact on the cluster formation. When cyclohexane was used as the dispersed phase, predominately, particle doublets and triplets
were obtained. The use of toluene-in-water emulsions resulted into a broader spectrum of clusters of up to 12 constituents.
Such clusters could satisfy the demand for particles with complex but defined shapes and special symmetries for the fabrication
of novel hierarchically organized materials. 相似文献
216.
Carlo Bianca 《Mathematical Methods in the Applied Sciences》2013,36(13):1768-1775
The thermostatted kinetic framework has been recently proposed in [C. Bianca, Nonlinear Analysis: Real World Applications 13 (2012) 2593‐2608] for the modeling of complex systems in the applied sciences under the action of an external force field that moves out of equilibrium the system. The framework consists in an integro‐differential equation with quadratic nonlinearity coupled with the Gaussian isokinetic thermostat. This paper is concerned with the existence of stationary solutions proof. The main result is gained by fixed point and measure theory arguments. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
217.
Fulvic acid enrichment in the microlayer of the Gerlache Inlet Sea (Antarctica): preliminary results
Nicoletta Calace Sabrina Mirante Bianca Maria Petronio Marco Pietroletti Cristina Rugo 《International journal of environmental analytical chemistry》2013,93(6-7):413-421
The aim of this work was to study the presence of fulvic acids in Antarctic waters, as they appear to be principal film-forming components in the surface microlayer. We obtained a series of samples during two Antarctic Italian Expeditions in 1998/99 and 2000/01 and studied the distribution and the structural differences between fulvic acids extracted from both microlayer and subsurface waters. Fulvic acids are concentrated in the microlayer and the enrichment factor between microlayer and subsurface water differs between samples. The enrichment factor values for fulvic acids lie between those found for dissolved organic carbon (DOC) and particulate organic carbon (POC) in the literature. Fulvic acids extracted from the microlayer were found to be different in structure from those present in the subsurface layer and enriched in sulphur content. We hypothesised that sulphur-containing compounds are slightly bound and/or occluded in fulvic acid structures. The sulphur-containing compounds analysed in the microlayer could be dimethylsulfide (DMS) and/or its products stemming from photochemical and biological oxidation reactions. 相似文献
218.
Bianca M. Saliba Satyam Khanal Michael A. ODonnell Kathryn E. Queenan Junho Song Matthew R. Gentile Seann P. Mulcahy 《Tetrahedron letters》2018,59(49):4311-4314
Two different pathways for the synthesis of annulated pyrido[3,4-b]indoles are reported using metal-catalyzed cyclotrimerization reactions. A stepwise process using Rh(I)-catalysis in the final step of the synthesis and a multicomponent, tandem catalytic approach using Pd(0)-catalysis both lead to complex nitrogen-containing heterocycles in good yields. Substituent effects are investigated for both pathways, demonstrating that the Pd(0)-catalyzed approach is more sensitive to electron-withdrawing groups. 相似文献
219.
220.