全文获取类型
收费全文 | 115篇 |
免费 | 13篇 |
国内免费 | 3篇 |
专业分类
化学 | 88篇 |
数学 | 17篇 |
物理学 | 26篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2017年 | 1篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 2篇 |
2013年 | 5篇 |
2012年 | 5篇 |
2011年 | 10篇 |
2010年 | 10篇 |
2009年 | 5篇 |
2008年 | 9篇 |
2007年 | 5篇 |
2006年 | 11篇 |
2005年 | 11篇 |
2004年 | 6篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有131条查询结果,搜索用时 15 毫秒
61.
A series of new Ru(II) arene phosphine complexes derived from Binap have been prepared. Specifically, reaction of Ru(OAc)(2)(Binap) with 3,5-(CF(3))(2)C(6)H(3))(4)B (BArF).H(OEt(2))(2), is shown to afford new mono- and dinuclear Ru(II) hydroxyphosphine pi-arene complexes via a series of P-C bond cleavage reactions. The dinuclear Ru(II) pi-arene complexes contain bridging P(O)(OH)(2) ligands. Crystal structures of five new complexes are reported and suggest an eta(4)-arene rather than an eta(6)-arene coordination mode. However, in solution, their (13)C NMR data are more consistent with a strongly distorted eta(6)-coordination mode. PGSE (1)H and (19)F diffusion measurements on the dinuclear complexes suggest hydrogen bonding of the triflate anion and ion-pairing of the BArF(-) anion. 相似文献
62.
Dr. Juliane Adler Monika Baumann Bruno Voigt Dr. Holger A. Scheidt Dr. Debanjan Bhowmik Dr. Tilmann Häupl Prof. Dr. Bernd Abel Prof. Dr. Perunthiruthy K. Madhu Prof. Dr. Jochen Balbach Prof. Dr. Sudipta Maiti Prof. Dr. Daniel Huster 《Chemphyschem》2016,17(17):2744-2753
A small library of rationally designed amyloid β [Aβ(1–40)] peptide variants is generated, and the morphology of their fibrils is studied. In these molecules, the structurally important hydrophobic contact between phenylalanine 19 (F19) and leucine 34 (L34) is systematically mutated to introduce defined physical forces to act as specific internal constraints on amyloid formation. This Aβ(1–40) peptide library is used to study the fibril morphology of these variants by employing a comprehensive set of biophysical techniques including solution and solid‐state NMR spectroscopy, AFM, fluorescence correlation spectroscopy, and XRD. Overall, the findings demonstrate that the introduction of significant local physical perturbations of a crucial early folding contact of Aβ(1–40) only results in minor alterations of the fibrillar morphology. The thermodynamically stable structure of mature Aβ fibrils proves to be relatively robust against the introduction of significantly altered molecular interaction patterns due to point mutations. This underlines that amyloid fibril formation is a highly generic process in protein misfolding that results in the formation of the thermodynamically most stable cross‐β structure. 相似文献
63.
Denifl S Zappa F Mähr I Mauracher A Probst M Märk TD Scheier P 《Journal of the American Chemical Society》2008,130(15):5065-5071
The inelastic electron interaction (ionization/attachment) with chloroform embedded in helium droplets has been studied utilizing a two-sector field mass spectrometer. Positive mass spectra have been recorded at the electron energy of 70 eV and are compared with previous results in the gas phase and with other systems embedded in helium droplets. Moreover, the negative ion mass spectrum has been recorded at the electron energy of 1.5 eV. Both negative and positive mass spectra show that chloroform clusters are easily formed by embedding single molecules in the helium droplets. Moreover, for anions appearing in the mass spectrum, the ion yield has been determined as function of the electron energy. While no parent anion of chloroform can be observed in the gas phase, the present cluster environment allows the stabilization of the transient negative ion. The influence of the helium droplet upon the ionization or attachment process of the embedded chloroform is discussed. 相似文献
64.
Fabio Zappa Dr. Manuel Beikircher Andreas Mauracher Stephan Denifl Dr. Michael Probst Prof. Dr. Natcha Injan Jumras Limtrakul Arntraud Bacher Dr. Olof Echt Prof. Dr. Tilmann D. Märk Prof. Dr. Paul Scheier Prof. Dr. Thomas A. Field Prof. Dr. Karola Graupner 《Chemphyschem》2008,9(4):607-611
A comprehensive analysis of metastable dissociation of 2,4‐dinitrotoluene (DNT) parent anions formed by attachment of electrons of controlled energy is presented. We characterize the energy dependence and kinetic energy release of the reaction which competes with autodetachment. A surprising finding is a highly exothermic metastable reaction triggered by the attachment of thermal electrons which we relate to the well‐known electrostatic ignition hazards of DNT and other explosives. Quantum chemical calculations are performed for dinitrobenzene in order to elucidate the process of NO abstraction. 相似文献
65.
Ptasińska S Denifl S Grill V Märk TD Illenberger E Scheier P 《Physical review letters》2005,95(9):093201
Electron attachment to gas phase thymine and uracil leads to H- loss within a broad and structured feature in the energy range between about 5 and 12 eV consisting of 4 overlapping resonances. By using thymine and uracil methylated at the N1 and N3 positions, respectively, and taking into account recent results from partly deuterated thymine, we find that by tuning the electron energy, H- loss turns out to be not only bond selective, i.e., (C-H) versus (N-H) bonds, but also site selective (N1 versus N3 site). Such a bond and site selectivity by energy has not been observed before in dissociative electron attachment. Implications for the mechanism of strand breaks observed in plasmid DNA are considered. 相似文献
66.
The crystal structure of a strontium-imidazolium polymeric material obtained from the reaction of zwitterionic 1,3-bis(carboxymethyl)imidazolium with SrCO(3) (2:1) in water is reported. The compound crystallized in the orthorhombic space group Pcc2 with a = 14.545(3) A, b = 8.514(5) A, c = 8.5619(14) A, V = 1060.2(6) A(3), and Z = 2. The macromolecular structure is constructed from 8-coordinate strontium, which binds to six different imidazolium carboxylate molecules. The two-dimensional polymer is separated by water sheets in which the water molecules form near-planar hexagons. 相似文献
67.
An online method for the analysis of volatile organic compounds in electronic cigarette aerosol based on proton transfer reaction mass spectrometry
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)
68.
Tilmann Gneiting 《Expositiones Mathematicae》2001,19(4):359-363
We discuss certain types of characteristic functions with surprising and interesting properties, settle two problems of Ushakov, relate to an observation by Ramachandran, and pose new questions. 相似文献
69.
Harald Schbel Marcin Dampc Filipe Ferreira da Silva Andreas Mauracher Fabio Zappa Stephan Denifl Tilmann D. Mrk Paul Scheier 《International journal of mass spectrometry》2009,280(1-3):26
Electron impact ionization of helium nano-droplets containing several 104 He atoms and doped with CCl4 or SF6 molecules is studied with high-mass resolution. The mass spectra show significant clustering of CCl4 molecules, less so for SF6 under our experimental conditions. Positive ion efficiency curves as a function of electron energy indicate complete immersion of the molecules inside the helium droplets in both cases. For CCl4 we observe the molecular parent cation CCl4+ that preferentially is formed via Penning ionization upon collisions with He*. In contrast, no parent cation SF6+ is seen for He droplets doped with SF6. The fragmentation patterns for both molecules embedded in He are compared with gas phase studies. Ionization via electron transfer to He+ forms highly excited ions that cannot be stabilized by the surrounding He droplet. Besides the atomic fragments F+ and Cl+ several molecular fragment cations are observed with He atoms attached. 相似文献
70.
We study the orbit structure and the geometric quantization of a pair of mutually commuting hamiltonian actions on a symplectic manifold. If the pair of actions fulfils a symplectic Howe condition, we show that there is a canonical correspondence between the orbit spaces of the respective moment images. Furthermore, we show that reduced spaces with respect to the action of one group are symplectomorphic to coadjoint orbits of the other group. In the Kähler case we show that the linear representation of a pair of compact connected Lie groups on the geometric quantization of the manifold is then equipped with a representation-theoretic Howe duality. 相似文献