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61.
62.
Schumann M Soldner T Deissenroth M Glück F Krempel J Kreuz M Märkisch B Mund D Petoukhov A Abele H 《Physical review letters》2007,99(19):191803
A new measurement of the neutrino asymmetry parameter B in neutron decay, the angular correlation between neutron spin and antineutrino momentum, is presented. The result, B=0.9802(50), confirms earlier measurements but features considerably smaller corrections. It agrees with the standard model expectation and permits updated tests on "new physics" in neutron decay. 相似文献
63.
Nannocystin A: an Elongation Factor 1 Inhibitor from Myxobacteria with Differential Anti‐Cancer Properties 下载免费PDF全文
Philipp Krastel Silvio Roggo Markus Schirle Nathan T. Ross Francesca Perruccio Peter Aspesi Jr. Thomas Aust Kathrin Buntin David Estoppey Brigitta Liechty Felipa Mapa Klaus Memmert Howard Miller Xuewen Pan Ralph Riedl Christian Thibaut Jason Thomas Trixie Wagner Eric Weber Xiaobing Xie Esther K. Schmitt Dr. Dominic Hoepfner 《Angewandte Chemie (International ed. in English)》2015,54(35):10149-10154
Cultivation of myxobacteria of the Nannocystis genus led to the isolation and structure elucidation of a class of novel cyclic lactone inhibitors of elongation factor 1. Whole genome sequence analysis and annotation enabled identification of the putative biosynthetic cluster and synthesis process. In biological assays the compounds displayed anti‐fungal and cytotoxic activity. Combined genetic and proteomic approaches identified the eukaryotic translation elongation factor 1α (EF‐1α) as the primary target for this compound class. Nannocystin A ( 1 ) displayed differential activity across various cancer cell lines and EEF1A1 expression levels appear to be the main differentiating factor. Biochemical and genetic evidence support an overlapping binding site of 1 with the anti‐cancer compound didemnin B on EF‐1α. This myxobacterial chemotype thus offers an interesting starting point for further investigations of the potential of therapeutics targeting elongation factor 1. 相似文献
64.
Mono‐, di‐ and trimethylated homologues of isoprenoid tetraether lipid cores in archaea and environmental samples: mass spectrometric identification and significance 下载免费PDF全文
Chris Knappy Daniela Barillà James Chong Dominic Hodgson Hugh Morgan Muhammad Suleman Christine Tan Peng Yao Brendan Keely 《Journal of mass spectrometry : JMS》2015,50(12):1420-1432
Higher homologues of widely reported C86 isoprenoid diglycerol tetraether lipid cores, containing 0–6 cyclopentyl rings, have been identified in (hyper)thermophilic archaea, representing up to 21% of total tetraether lipids in the cells. Liquid chromatography‐tandem mass spectrometry confirms that the additional carbon atoms in the C87‐88 homologues are located in the etherified chains. Structures identified include dialkyl and monoalkyl (‘H‐shaped’) tetraethers containing C40‐42 or C81‐82 hydrocarbons, respectively, many representing novel compounds. Gas chromatography‐mass spectrometric analysis of hydrocarbons released from the lipid cores by ether cleavage suggests that the C40 chains are biphytanes and the C41 chains 13‐methylbiphytanes. Multiple isomers, having different chain combinations, were recognised among the dialkyl lipids. Methylated tetraethers are produced by Methanothermobacter thermautotrophicus in varying proportions depending on growth conditions, suggesting that methylation may be an adaptive mechanism to regulate cellular function. The detection of methylated lipids in Pyrobaculum sp. AQ1.S2 and Sulfolobus acidocaldarius represents the first reported occurrences in Crenarchaeota. Soils and aquatic sediments from geographically distinct mesotemperate environments that were screened for homologues contained monomethylated tetraethers, with di‐ and trimethylated structures being detected occasionally. The structural diversity and range of occurrences of the C87‐89 tetraethers highlight their potential as complementary biomarkers for archaea in natural environments. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
65.
Torsten Roth Vladislav Vasilenko Callum G. M. Benson Hubert Wadepohl Dominic S. Wright Lutz H. Gade 《Chemical science》2015,6(4):2506-2510
A simple, “click” synthetic approach to a new type of hybrid phosph(III)azane/NHC system is described. The presence of the phosphazane P2N2 ring unit, with P atoms flanking the NCN fragment and with this ring perpendicular to the binding site of the NHC, provides unique opportunities for modifying the electronic and steric character of these carbenes. 相似文献
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Dominic Brenner Andreas Dellnitz Wilhelm Rödder 《The Journal of mathematical sociology》2017,41(2):84-103
To detect and study cohesive subgroups of actors is a main objective in social network analysis. What are the respective relations inside such groups and what separates them from the outside. Entropy-based analysis of network structures is an up-and-coming approach. It turns out to be a powerful instrument to detect certain forms of cohesive subgroups and to compress them to superactors without loss of information about their embeddedness in the net: Compressing strongly connected subgroups leaves the whole net’s and the (super-)actors’ information theoretical indices unchanged; i.e., such compression is information-invariant. The actual article relates on the reduction of networks with hundreds of actors. All entropy-based calculations are realized in an expert system shell. 相似文献
69.
Dominic G. B. Edelen 《Archive for Rational Mechanics and Analysis》1972,44(5):359-375
This paper investigates the structure of theories that obtain from variational statements that are invariant under the action of a gauge group. Partial differential equations are obtained for the gauge group and for the infinitesimal generators of the gauge group. These are used to derive partial differential equations whose solutions give Lagrangian functions that result in action functionals that are strongly invariant under the gauge group. Properties of the Euler equations for such theories are analyzed, where it is shown that it is always possible to add a gauge condition to such theories when the data is of Neumann type. The results are illustrated by theories for the interaction of a vector 4-potential with a finite number of matter fields. The current and the charge-current potentials are shown to be determined from knowledge of the Lagrangian function and of the infinitesimal generators of the gauge transformations of the matter fields. 相似文献
70.
A technique to optimize the stability of a general mechanical system is outlined. The method relies on decomposing the damping matrix into several component matrices, which may have some special structure or physical relevance. An optimization problem can then be formulated where the ratio of these are varied to either stabilize or make more stable the equilibrium state subject to sensible constraints. For the purpose of this study, we define a system to be more stable if its eigenvalue with largest real part is as negative as possible. The technique is demonstrated by applying it to an introduced non-dimensionalized variant of a known minimal wobbling disc brake model. In this case, it is shown to be beneficial to shift some damping from the disc to the pins for a system optimized for stability. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献