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Phase Diagrams of Alkali Bromide - Lanthanoid(III) Bromide Mixtures The phase diagrams of the systems KBr? PrBr3 (NdBr3, SmBr3, GdBr3, DyBr3, ErBr3, YbBr3), RbBr? NdBr3 (SmBr3, GdBr3, DyBr3, ErBr3, YbBr3) and CsBr? PrBr3 (NdBr3, SmBr3, GdBr3, ErBr3, YbBr3) were determined by differential thermal analysis and differential scanning calorimetry. The compound M3LnBr6, whose stability increases with increasing size of the alkali cation resp. decreasing of the Ln3+ ion, was found in all investigated systems. Additionaly congruently melting compounds of the type MLn2Br7 were found in the system from PrBr3 to DyBr3 which are, however, peritectic in systems with smaller alkali cations. Another peritectic compound has the composition M2LnBr5, in case that the quotient rMe+rX?/rLn3+ exceeds 3 this composition shifts to M3Ln2Br9. The compounds M3LnBr6 have a transition with a transition temperature, which is concentration dependent. This May indicate that at the composition ?M3LnBr6”? in fact two compounds exist with slightly different composition, of which one is stable at higher the other at lower temperatures. 相似文献
44.
Miltner A Richnow HH Kopinke FD Kästner M 《Isotopes in environmental and health studies》2005,41(2):135-140
In general, soils without the vegetation growing on them are regarded as sources of CO2. However, there are indications that CO2 is also fixed by soil microorganisms. Although this process is not significant from a quantitative point of view, it may change the isotopic composition of soil organic matter. Therefore, we conducted an incubation study with soil and 13C-labeled CO2 to investigate this process. We found that the label was transferred from CO2 into organic compounds in soil. At the end of a 61-day incubation period, 1.3 micromol C g(-1) soil, corresponding to approximately 0.08% of the soil organic carbon, had been fixed. CO2 may, therefore, be an additional source of soil organic carbon. Compound-specific analysis of amino sugars, amino acids, and fatty acids indicated that the label is incorporated into microbial, mainly bacterial, biomass. All groups of microorganisms were involved in the assimilation of CO2, but the relatively high enrichment of mono-unsaturated and mid-chain branched fatty acids indicates that gram negative bacteria and actinomycetes may be slightly more important in this process than other groups of microorganisms. 相似文献
45.
[reaction: see text] The use of the p-toluenesulfonyl (Ts) and tosylvinyl (Tsv) groups as nitrogen masking groups imparted high regioselectivity in Diels-Alder reactions directed toward members of the oroidin-derived marine alkaloid family. The electron-withdrawing Tsv group was utilized as an electronically adjustable nitrogen-protecting group as subsequent hydrogenation provided the more electron-rich tosylethyl (Tse) group. This electronic adjustment strategy avoided a protecting group exchange and provided the required electronics for the key chlorination/ring-contraction sequence. 相似文献
46.
We discuss the zero field superconducting phase transition in a finite system of magnetically coupled superconducting layers. Transverse screening is modified by the presence of other layers resulting in topological excitations with fractional flux. Vortex stacks trapping a full flux and present at any finite temperature undergo a dissociation transition which corresponds to the depairing of fractional-flux vortices in individual layers. We propose an experiment with a bilayer system allowing us to identify the dissociation of bound vortex molecules. 相似文献
47.
We investigate the collision of two vortex lines moving with viscous dynamics and driven towards each other by an applied current. Using London theory in the approach phase we observe a nontrivial vortex conformation producing antiparallel segments; their attractive interaction triggers a violent collision. The collision region is analyzed using the time-dependent Ginzburg-Landau equation. While we find that vortices will always recombine through the exchange of segments, a crossing channel appears naturally through a double collision process. 相似文献
48.
Background
In hippocampal neurons, nuclear calcium signaling is important for learning- and neuronal survival-associated gene expression. However, it is unknown whether calcium signals generated by neuronal activity at the cell membrane and propagated to the soma can unrestrictedly cross the nuclear envelope to invade the nucleus. The nuclear envelope, which allows ion transit via the nuclear pore complex, may represent a barrier for calcium and has been suggested to insulate the nucleus from activity-induced cytoplasmic calcium transients in some cell types. 相似文献49.
Parvin Zare Maria Mahrova Emilia Tojo Anja Stojanovic Wolfgang H. Binder 《Journal of polymer science. Part A, Polymer chemistry》2013,51(1):190-202
A facile synthetic route for the preparation of dicationic ethylene glycol based‐ionic liquids (ILs) via the azide/alkyne “click” reaction is presented. The copper(I) catalyzed, microwave‐assisted azide/alkyne “click” reaction between diazido‐ethylene glycols and the corresponding alkyne containing IL‐head group enables a simple preparation of different sets of poly(ethylene glycol)‐based ILs. Beside tetra‐ and hexa(ethylene glycol)‐based ILs, also oligomeric (Mn = 400 g/mol) and polymeric ILs (Mn up to 1550 g/mol) could be prepared in good yield and with full conversion of the ionic head group. The prepared ILs were extensively characterized via NMR spectroscopy and ESI‐time‐of‐flight (TOF) mass spectroscopy, revealing the formation of multiply charged ions in the negative mode. Thermal stability proved to be exceptionally high (up to 300 °C) together with low glass‐transition temperatures. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献