全文获取类型
收费全文 | 408篇 |
免费 | 18篇 |
专业分类
化学 | 281篇 |
力学 | 14篇 |
数学 | 57篇 |
物理学 | 74篇 |
出版年
2023年 | 3篇 |
2019年 | 8篇 |
2017年 | 8篇 |
2016年 | 7篇 |
2015年 | 8篇 |
2014年 | 4篇 |
2013年 | 8篇 |
2012年 | 10篇 |
2011年 | 13篇 |
2010年 | 10篇 |
2009年 | 17篇 |
2008年 | 12篇 |
2007年 | 10篇 |
2006年 | 12篇 |
2005年 | 11篇 |
2004年 | 8篇 |
2003年 | 17篇 |
2002年 | 17篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1998年 | 7篇 |
1996年 | 4篇 |
1995年 | 9篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1979年 | 11篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1976年 | 4篇 |
1975年 | 8篇 |
1974年 | 6篇 |
1973年 | 7篇 |
1971年 | 3篇 |
1970年 | 5篇 |
1938年 | 3篇 |
1932年 | 4篇 |
1931年 | 3篇 |
排序方式: 共有426条查询结果,搜索用时 15 毫秒
51.
52.
Willi Ammann Ren Richarz Toni Wirthlin Detlef Wendisch 《Magnetic resonance in chemistry : MRC》1982,20(4):260-265
2D NMR techniques (J-resolved 13C, 13C? 13C correlated, 1H? 13C correlated) were used to gather more chemical shift and coupling information on the pentacyclic triterpene, lupane. They confirm and complete 13C assignments made earlier, and corroborate the constitution and major configurational details of lupane. Lupane is a parent compound and spectral reference in the study of sedimental demethylated triterpenes. 相似文献
53.
54.
Willi R. Bihn E. M. Fels H. Müller-Merbach L. Czayka 《Mathematical Methods of Operations Research》1963,7(4):189-192
Ohne Zusammenfassung 相似文献
55.
Kar S Borghesi M Bulanov SV Key MH Liseykina TV Macchi A Mackinnon AJ Patel PK Romagnani L Schiavi A Willi O 《Physical review letters》2008,100(22):225004
Experimental evidence of plasma jets ejected from the rear side of thin solid targets irradiated by ultraintense (>10(19) W cm(-2)) laser pulses is presented. The jets, detected by transverse interferometric measurements with high spatial and temporal resolutions, show collimated expansion lasting for several hundreds of picoseconds and have substantially steep density gradients at their periphery. The role played by radiation pressure of the laser in the jet formation process is highlighted analytically and by extensive two-dimensional particle-in-cell simulations. 相似文献
56.
57.
A new organic reference material,l‐glutamic acid,USGS41a,for δ13C and δ15N measurements − a replacement for USGS41
下载免费PDF全文
![点击此处可从《Rapid communications in mass spectrometry : RCM》网站下载免费的PDF全文](/ch/ext_images/free.gif)
58.
59.
Willi R. Berg Dr. Jonathan F. Berengut Changzhuang Bai Dr. Laura Wimberger Prof. Lawrence K. Lee Dr. Felix J. Rizzuto 《Angewandte Chemie (International ed. in English)》2023,62(51):e202314458
Hierarchical DNA nanostructures offer programmable functions at scale, but making these structures dynamic, while keeping individual components intact, is challenging. Here we show that the DNA A-motif—protonated, self-complementary poly(adenine) sequences—can propagate DNA origami into one-dimensional, micron-length fibrils. When coupled to a small molecule pH regulator, visible light can activate the hierarchical assembly of our DNA origami into dissipative fibrils. This system is recyclable and does not require DNA modification. By employing a modular and waste-free strategy to assemble and disassemble hierarchical structures built from DNA origami, we offer a facile and accessible route to developing well-defined, dynamic, and large DNA assemblies with temporal control. As a general tool, we envision that coupling the A-motif to cycles of dissipative protonation will allow the transient construction of diverse DNA nanostructures, finding broad applications in dynamic and non-equilibrium nanotechnology. 相似文献
60.
Auwärter W Klappenberger F Weber-Bargioni A Schiffrin A Strunskus T Wöll C Pennec Y Riemann A Barth JV 《Journal of the American Chemical Society》2007,129(36):11279-11285
We present a combined low-temperature scanning tunneling microscopy and near-edge X-ray adsorption fine structure study on the interaction of tetrapyridyl-porphyrin (TPyP) molecules with a Cu(111) surface. A novel approach using data from complementary experimental techniques and charge density calculations allows us to determine the adsorption geometry of TPyP on Cu(111). The molecules are centered on "bridge" sites of the substrate lattice and exhibit a strong deformation involving a saddle-shaped macrocycle distortion as well as considerable rotation and tilting of the meso-substituents. We propose a bonding mechanism based on the pyridyl-surface interaction, which mediates the molecular deformation upon adsorption. Accordingly, a functionalization by pyridyl groups opens up pathways to control the anchoring of large organic molecules on metal surfaces and tune their conformational state. Furthermore, we demonstrate that the affinity of the terminal groups for metal centers permits the selective capture of individual iron atoms at low temperature. 相似文献