全文获取类型
收费全文 | 697篇 |
免费 | 6篇 |
国内免费 | 9篇 |
专业分类
化学 | 394篇 |
晶体学 | 1篇 |
力学 | 16篇 |
数学 | 116篇 |
物理学 | 185篇 |
出版年
2022年 | 5篇 |
2019年 | 10篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2014年 | 7篇 |
2013年 | 18篇 |
2012年 | 25篇 |
2011年 | 28篇 |
2010年 | 15篇 |
2009年 | 18篇 |
2008年 | 24篇 |
2007年 | 30篇 |
2006年 | 43篇 |
2005年 | 45篇 |
2004年 | 22篇 |
2003年 | 15篇 |
2002年 | 19篇 |
2001年 | 24篇 |
2000年 | 13篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1988年 | 12篇 |
1987年 | 9篇 |
1986年 | 13篇 |
1985年 | 17篇 |
1984年 | 15篇 |
1982年 | 13篇 |
1981年 | 10篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1977年 | 10篇 |
1976年 | 7篇 |
1975年 | 12篇 |
1974年 | 9篇 |
1973年 | 11篇 |
1971年 | 5篇 |
1966年 | 6篇 |
1938年 | 10篇 |
1933年 | 4篇 |
1890年 | 4篇 |
排序方式: 共有712条查询结果,搜索用时 9 毫秒
161.
162.
163.
164.
One‐Dimensional Arsenic Allotropes: Polymerization of Yellow Arsenic Inside Single‐Wall Carbon Nanotubes 下载免费PDF全文
Martin Hart Dr. Ji Chen Prof. Angelos Michaelides Prof. Andrea Sella Prof. Milo S. P. Shaffer Dr. Christoph G. Salzmann 《Angewandte Chemie (International ed. in English)》2018,57(36):11649-11653
The pnictogen nanomaterials, including phosphorene and arsenene, display remarkable electronic and chemical properties. Yet, the structural diversity of these main group elements is still poorly explored. Here we fill single‐wall carbon nanotubes with elemental arsenic from the vapor phase. Using electron microscopy, we find chains of highly reactive As4 molecules as well as two new one‐dimensional allotropes of arsenic: a single‐stranded zig‐zag chain and a double‐stranded zig‐zag ladder. These linear structures are important intermediates between the gas‐phase clusters of arsenic and the extended sheets of arsenene. Raman spectroscopy indicates weak electronic interaction between the arsenic and the nanotubes which implies that the formation of the new allotropes is driven primarily by the geometry of the confinement. The relative stabilities of the new arsenic structures are estimated computationally. Band‐gap calculations predict that the insulating As4 chains become semiconducting, once converted to the zig‐zag ladder, and form a fully metallic allotrope of arsenic as the zig‐zag chain. 相似文献
165.
L.P. Hart B.W. Smith N. Omenetto 《Spectrochimica Acta Part B: Atomic Spectroscopy》1986,41(12):1367-1380
Absolute number densities for the metastable and radiative 4s argon levels in an inductively coupled plasma have been determined for a variety of plasma conditions by the technique of continuum source absorption. As primary source, a 300 W xenon arc was used and much care was taken in screening the optical detection system from the intense background emission of the plasma. A 1.29-m focal length grating monochromator provided a variable bandwidth so that absorption measurements could be carried out, with varying degree of sensitivity, on 19 different argon lines. The number densities were derived from the corresponding curves of growth, calculated for each line. Concentrations ranging from 2.3 × 1010 to 7.4 × 1011 cm−3 were obtained for the different levels, depending upon the presence or absence of nebulizing gas and water in the plasma. At observation heights greater than 20 mm above the coil, the number density approaches the value predicted by Boltzman equilibrium for a temperature of 6500 K. The detection sensitivity of the present apparatus is about 5 × 109 cm−3. For seven lines, damping parameter values were also estimated and found to vary from 0.4 to 1.1. 相似文献
166.
Aubert B Barate R Boutigny D Couderc F Gaillard JM Hicheur A Karyotakis Y Lees JP Tisserand V Zghiche A Palano A Pompili A Chen JC Qi ND Rong G Wang P Zhu YS Eigen G Ofte I Stugu B Abrams GS Borgland AW Breon AB Brown DN Button-Shafer J Cahn RN Charles E Day CT Gill MS Gritsan AV Groysman Y Jacobsen RG Kadel RW Kadyk J Kerth LT Kolomensky YG Kukartsev G Lynch G Mir LM Oddone PJ Orimoto TJ Pripstein M Roe NA Ronan MT Shelkov VG Wenzel WA Barrett M Ford KE Harrison TJ Hart AJ Hawkes CM Morgan SE 《Physical review letters》2005,94(10):101801
We search for the rare flavor-changing neutral-current decay B(+)--> K(+)nunu in a data sample of 82 fb(-1) collected with the BABAR detector at the PEP-II B-factory. Signal events are selected by examining the properties of the system recoiling against either a reconstructed hadronic or semileptonic charged-B decay. Using these two independent samples we obtain a combined limit of B(B(+)-->K(+)nunu ) < 5.2 x 10(-5) at the 90% confidence level. In addition, by selecting for pions rather than kaons, we obtain a limit of B(B+-->pi(+)nunu) < 1.0 x 10(-4) using only the hadronic B reconstruction method. 相似文献
167.
锂离子电池正极材料正在向着高比能量、长寿命、低成本、环境友好的方向发展,而具有橄榄石结构的LiFePO4正极材料以其结构稳定、成本低、无污染等优点成为21世纪最理想的绿色电源,但自身也存在缺点。综述了锂离子电池正极材料LiFePO4的研究进展。系统地阐述了LiFePO4的晶体结构特征及性能、多种合成方法以及掺杂多种导电材料和控制晶体生长制备纳米粉体对材料性能的影响。对该材料的应用前景进行了展望,并提出了下一步可能的研究趋势。 相似文献
168.
Igor A. Sedov Timur I. Magsumov Erin Hart Ashley M. Ramirez Sarah Cheeran Maribel Barrera Melissa Y. Horton Anisha Wadawadigi Olivia Zha Xin Y. Tong William E. AcreeJr. Michael H. Abraham 《Journal of solution chemistry》2017,46(12):2249-2267
A gas chromatographic headspace analysis method was used to experimentally determine gas-to-liquid partition coefficients and infinite dilution activity coefficients for 29 liquid organic solutes dissolved in triethylene glycol at 298.15 K. Solubilities were also determined at 298.15 K for 23 crystalline nonelectrolyte organic compounds in triethylene glycol based on spectroscopic absorbance measurements. The experimental results of the headspace chromatographic and spectroscopic solubility measurements were converted to gas-to-triethylene glycol and water-to-triethylene glycol partition coefficients, and molar solubility ratios using standard thermodynamic relationships. Expressions were derived for solute transfer into triethylene glycol by combining our measured experimental values with published literature data. Mathematical correlations based on the Abraham model describe the observed partition coefficient and solubility data to within 0.16 log10 units (or less). 相似文献
169.
170.
Joseph Openy Gulshan Amrahova Jen-Yao Chang Dr. Anaïs Noisier Dr. Peter ‘t Hart 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(39):e202201121
Introduction of unnatural amino acids can significantly improve the binding affinity and stability of peptides. Commercial availability of such amino acids is limited, and their synthesis is a long and tedious process. We here describe a method that allows the functionalization of peptides directly on solid-support by converting lysine residues to Katritzky salts, and subjecting them to a photochemical Giese reaction under mild reaction conditions. The method avoids the need for amino acid synthesis and instead offers a late-stage modification route for rapid peptide diversification. While numerous modification approaches at the lysine amine have been described, this work provides the first example of deaminative functionalization of peptides at lysine. The two-step protocol is compatible with various substrates, lysine analogues, resins, and all proteinogenic amino acids. Finally, by leveraging solid-phase modification, this protocol facilitates the functionalization of longer peptides as was demonstrated using biologically relevant peptides of up to 15 amino acids. 相似文献