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71.
Gerhart Braunegg Klaus Genser Rodolfo Bona Gudrun Haage Florian Schellauf Elisabeth Winkler 《Macromolecular Symposia》1999,144(1):375-383
Polyhydroxyalkanoates (PHAs) are biodegradable substitutes to fossil fuel plastics that can be produced from renewable raw materials such as saccharides, alcohols and low-molecular-weight fatty acids. They are completely degradable to carbon dioxide and water through natural microbiological mineralization. Consequently, neither their production nor their use or degradation have a negative ecological impact. By keeping closed the cycle of production and re-use, PHAs can enable at least part of the polymer-producing industry to switch from ecologically harmful end-of-the-pipe production methods towards sounder technologies. Up to now such polyesters have been produced biotechnologically from refined raw materials (e.g. glucose and sodium propionate), but they can as well be produced much cheaper from agricultural waste materials (e.g. molasses, maltose, glycerol phase from biodiesel production, whey), as long as these materials have a known composition and are available in appropriate quantities. Yield factors and specific rates for growth and PHA accumulation are shown for 3 strains of Alcaligenes latus for different agricultural waste carbon sources. 相似文献
72.
Martin Koller Aid Atlić Yolanda Gonzalez-Garcia Christoph Kutschera Gerhart Braunegg 《Macromolecular Symposia》2008,272(1):87-92
Summary: The potential of three different microbial wild type strains as polyhydroxyalkanoate (PHA) producers from whey lactose is compared. Homopolyester and co-polyester biosynthesis was investigated by the archaeon Haloferax mediterranei and the eubacterial strains Pseudomonas hydrogenovora and Hydrogenophaga pseudoflava. H. mediterranei accumulated 50 wt.-% of poly-3-(hydroxybutyrate-co-6%-hydroxyvalerate) in cell dry mass from hydrolyzed whey without addition of 3-hydroxyvalerate (3HV) precursors (specific productivity qp: 2.9 mg/g h). Using P. hydrogenovora, the final percentage of poly-3-hydroxybutyrate (PHB) amounted to 12 wt.-% (qp: 0.03 g/g h); co-feeding of valeric acid resulted in the production of 12 wt.-%. P-3(HB-co-21%-HV) (qp: 0.02 g/g h). With H. pseudoflava, it was possible to reach 40 wt.-% P-3 (HB-co-5%-HV) on not-hydrolyzed whey lactose plus valeric acid as 3HV precursor (qp: 9.1 mg/g h); on hydrolyzed whey lactose without addition of valeric acid, the strain produced 30 wt.-% of PHB (qp: 0.16 g/g h). The characterization of the isolated biopolyesters completes the study. 相似文献
73.
Stefan Wyhlidal Dieter Rank Katharina Schott Gerhard Heiss Jason Goetz 《Isotopes in environmental and health studies》2014,50(4):448-460
Results of stable isotope measurements (δ2H, δ18O) of daily grab samples, taken from the Danube River at Tulln (river km 1963) during 2012, show seasonal and short-term variations depending on the climatic/hydrological conditions and changes in the catchment area (temperature changes, heavy rains and snow melt processes). Isotope ratios in river water clearly reflect the isotopic composition of precipitation water in the catchment area since evaporation influences play a minor role. Average δ2H and δ18O values in 2012 are?78‰ and?11.0‰, respectively, deuterium excess averages 10‰. The entire variation amounts to 1.8‰ in δ18O and 15‰ in δ2H. Quick changes of the isotopic composition within a few days emphasise the necessity of daily sampling for the investigation of hydrological events, while monthly grab sampling seems sufficient for the investigation of long-term hydro-climatic trends. 3H results show peaks (half-width 1–2 days, up to about 150 TU) exceeding the regional environmental level of about 9 TU, probably due to releases from nuclear power plants. 相似文献
74.
Matthias Schott Monica Dunford 《The European Physical Journal C - Particles and Fields》2014,74(7):1-59
This review summarises the main results on the production of single vector bosons in the Standard Model, both inclusively and in association with light- and heavy-flavour jets, at the Large Hadron Collider in proton–proton collisions at a centre-of-mass energy of \(7\,{\mathrm {\ TeV}}\) . The general purpose detectors at this collider, ATLAS and CMS, each recorded an integrated luminosity of \({\approx } 40\,\mathrm{pb^{-1}}\) and \(5\,\mathrm{fb^{-1}}\) in the years 2010 and 2011, respectively. The corresponding data offer the unique possibility to precisely study the properties of the production of heavy vector bosons in a new energy regime. The accurate understanding of the Standard Model is not only crucial for searches of unknown particles and phenomena but also to test predictions of perturbative Quantum-Chromodynamics calculations and for precision measurements of observables in the electroweak sector. Results from a variety of measurements in which single \(W\) or \(Z\) bosons are identified are reviewed. Special emphasis in this review is given to interpretations of the experimental results in the context of state-of-the-art predictions. 相似文献
75.
A number of techniques exist for minimizing the computational cost of discrete element simulations (DEMs). One such method is a reduction of particle stiffness, which allows for bigger time steps and therefore fewer iterations in a simulation. However, the limits and drawbacks of this approach are still unclear, and may lead to invalid results. This paper investigates the effect of a stiffness reduction on bulk behavior by examining three case studies. Two cases demonstrate that particle stiffness can be reduced without affecting the bulk material behavior, whereas the third test shows that a stiffness reduction influences the bulk behavior. 相似文献
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Summary A critical step in the chemical preparation of oligonucleotides is the chromatographic purification of the deprotected oligomers.
In case of large quantities of reaction products, the oligonucleotides are first enriched on a QAE-Sephadex column at low
pressure. The obtained fractions are then purified by multidimensional chromatography making use of three independent physical
properties of the solutes: molecular size, ionic net charge and hydrophobicity. In the first dimension size exclusion chromatography
(Sephadex G-15) is used. In the second dimension the high molecular weight fraction from the size exclusion chromatography
is applied to a HPLC ion-exchange column (Partisil-10 SAX). Usually the last peak is collected and transferred to a HPLC reversed
phase column (Nucleosil C18) where the components are separated according to their hydrophobicity in the third dimension.
The efficiency of this multi-dimensional chromatographic procedure is demonstrated by the unequivocal fingerprints after radioactive
labelling of the isolated oligonucleotides.
Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984 相似文献
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