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31.
H. G. Börner H. R. Koch H. Seyfarth T. von Egidy W. Mampe J. A. Pinston K. Schreckenbach D. Heck 《Zeitschrift für Physik A Hadrons and Nuclei》1978,286(1):31-43
For the investigation of vibrational states in odd A nuclei we have studied the level structure of239U by the238U (n thermal,γ) reaction. Various complementary measurement techniques as curved-crystal-, anti-Compton-,γ-γ coincidence- and conversion electron spectroscopy have been applied. The resulting data have been used to establish the deexcitation scheme of239U up to ~1.3 MeV and to make spin assignments. Most of the levels are interpreted in terms of the Nilsson model. The data also indicate the presence of the Nilsson states ¦501?¦ and ¦750¦. Three members of theΒ-vibrational band built on the ¦631?¦ state and one member of theΒ-vibration built on the ¦622↑¦ ground state have been identified through transitions with strongE0 admixtures. The octupole vibrational state built on the ¦631?¦ band is proposed at 815 keV. 相似文献
32.
C.-D. Zhao G. Haase M. Heck M. Tufail P. Vater H. A. Khan 《Isotopes in environmental and health studies》2013,49(6):296-299
222Rn dissolved in drilling fluids of the KTB (Kontinentales Tiefbohrprogramm der Bundesrepublik Deutschland) pilot hole has been determined using solid state nuclear track detector (SSNTD) technique:The α-sensitive SSNTD CR-39 was used to measure the a-activity of 222Rn. Well-defined conditions for Rn-measurements could be established by employing a mica nuclear track microfilter to separate the detector containing air volume from the volume containing the water. This technique has been applied to determine quantitatively the 222 Rn-concentration as a function of depth of the borehole down to 4000 m. 相似文献
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Capillary polystyrene-divinylbenzene (PS-DVB) monolithic columns were used to separate differentially acetylated intact IM9 protein isoforms. Compared to the unmodified form, the hydrophobic shift for intact acetylated isoforms was significant under standard reversed-phase conditions (32.5-45% acetonitrile in 10 min). The high chromatographic resolution of the PS-DVB monolithic columns resulted in peak widths at half height of 4-5s. This allowed us to nearly completely resolve a number of peaks greater than the number of possible acetylation sites. This observation suggested that not only the number, but also the location of the acetylations on the protein had a significant effect on the retention. Matrix-assisted laser desorption ionization time-of-flight MS and MS/MS were used to confirm the chromatographic separation of isoforms. It was found that the acetylations site, especially on the N-terminus, has an effect on the retention on the PS-DVB column. 相似文献
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36.
van Breukelen B Barendregt A Heck AJ van den Heuvel RH 《Rapid communications in mass spectrometry : RCM》2006,20(16):2490-2496
A complicating factor in analyzing electrospray ionization mass spectra of intact macromolecular heterogeneous protein complexes is the potential overlap of ions from different species present in solution. Therefore, it is often not possible to assign all ion signals. With the aim of allowing the more efficient and comprehensive analysis of very complex mass spectra of intact heterogeneous protein complexes we developed a software program: SOMMS. The program uses simple user input parameters together with Gaussian curve fitting to simulate putative mass spectra of protein (sub)complexes within a specified charge state window. In addition, the program can simulate spectra for heterogeneous protein complexes using bi- and multinomial distributions and it can calculate zero-charge spectra and relatively quantify the abundance of each component in a mixture. As a proof of concept we analyzed the complex mass spectra of alpha-glutamate synthase and alphabeta-glutamate synthase from Azosprillum brasilense. Using our program we could determine that alpha-glutamate synthase is in equilibrium between its dimeric, tetrameric, hexameric and dodecameric conformation, whereas alphabeta-glutamate synthase forms up to 15 different heterooligomeric assemblies composed of alpha- and beta-subunits. Thus, SOMMS allows resolving stoichiometries and oligomeric states of protein complexes even from very complicated mass spectra. These complexes could not be assigned by using maximum entropy calculations. We compared our mass spectrometry data on glutamate synthases with available X-ray, small-angle X-ray scattering and size-exclusion chromatography data. 相似文献
37.
Christoph Behrendt Jurgen Heck Michael J. McGlinchey 《Journal of organometallic chemistry》2006,691(6):1183-1196
The aldol condensation reaction between [Co(η4-C4Ph4){η5-C5H4C(O)CH3}] and a range of aromatic aldehydes [RCHO] and [RCHCH-CHO] gives a series of α,β-unsaturated ketones [Co(η4-C4Ph4){η5-C5H4C(O)CHCH-R}] and [Co(η4-C4Ph4){η5-C5H4C(O)CHCH-CHCH-R}] (3). The reaction is promoted by various bases: NaH proved to be the most effective whilst nBuLi gave [Co(η4-C4Ph4){η5-C5H4C(OH)(nBu)CH3}] as the major product. NaOH was ineffective, perhaps indicating that that the methyl protons in [Co(η4-C4Ph4){η5-C5H4C(O)CH3}] are less acidic than those in [Fe(η5-C5H5){η5-C5H4C(O)CH3}]. Compounds 3 were characterised spectroscopically. Their 1H NMR spectra are consistent with a trans configuration about their CC bond, and this was confirmed by X-ray crystallography in five cases, which showed that all have the same basic structure with parallel cyclobutadiene and cyclopentadienyl ligands, but they are not identical. The C5H4C(O)(CHCH)n-R (n = 1 or 2) moieties show little evidence for delocalisation and often deviate from planarity. The UV/Vis spectra of those 3 with smaller aromatic rings (R = C6H5, 4-C6H4NMe2, 2-C4H3S and 1-C10H7) suggest that these are donor-π-acceptor systems, but as the annellation of R increases (R = 9-C14H9, 1-C16H9 and 1-C20H11) the spectra increasingly resemble those of the parent polycyclic aromatic hydrocarbon, RH. Reduction of [Co(η4-C4Ph4){η5-C5H4C(O)CHCH-C10H7-1}] with DIBAL gives a mixture of [Co(η4-C4Ph4){η5-C5H4C(O)CH2CH2-C10H7-1}] and [Co(η4-C4Ph4){η5-C5H4CH(OH)CHCH-C10H7-1}]. A minor product from the preparation of [Co(η4-C4Ph4){η5-C5H4C(O)CH3}] was shown by X-ray crystallography to be the η4-butadiene complex [Co{η4-Ph(H)CC(Ph)-C(Ph)C(H)Ph}{η5-C5H4C(O)CH3}]. 相似文献
38.
Jared F. Bauters James R. Adleman Martijn J. R. Heck John E. Bowers 《Applied Physics A: Materials Science & Processing》2014,116(2):427-432
Planar waveguides with ultra-low propagation loss are necessary for integrating optoelectronic systems that require long optical time delay or narrowband optical filters. In this paper, we review an ultra-low loss planar waveguide platform that uses thin (<150 nm) Si3N4 cores and thick (>8 μm) SiO2 cladding layers. In particular, we discuss the performance of arrayed waveguide gratings (AWGs) fabricated with the platform. We propose the use of a practical design method that takes the statistical nature of worst-case crosstalk into account. We also demonstrate the measurement of amplitude and phase error distributions in an AWG using an optical backscatter reflectometer. We show that the waveguides have phase errors small enough to achieve AWG crosstalk below ?30 dB, while crosstalk below ?40 dB should also be possible with optimization of the component design. 相似文献
39.
Kleinnijenhuis AJ Heck AJ Duursma MC Heeren RM 《Journal of the American Society for Mass Spectrometry》2005,16(10):1595-1601
We studied lacticin 481, a small lantibiotic with three lanthionine bridges, by electron capture dissociation (ECD) in a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. Following electron capture, very little fragmentation was observed, but species formed by nondissociative single and multiple electron capture were abundant. Ions formed by double electron capture were subjected to sustained off resonance irradiation collision induced dissociation (SORI-CID) to determine whether stable biradicals were formed. In the SORI-CID spectra of the ions formed by double electron capture, some, but minor, H* radical loss was observed, which was not observed at all for regularly protonated ions. A small part of the ions formed by double electron capture are thus long-lived biradicals. Apart from the observed H* loss, the SORI-CID spectra of ions that captured two electrons was similar to that of regularly protonated ions and quite different from the SORI-CID spectra of radical ions formed by single electron capture. This implies that recombination of the two radical sites is the dominant process in biradical lacticin 481 ions, at least on the time scale of our SORI-CID experiments. 相似文献
40.
J C Waterval G Hommels P Bestebreurtje C Versluis A J Heck A Bult H Lingeman W J Underberg 《Electrophoresis》2001,22(13):2709-2716
An earlier developed capillary electrophoresis (CE) system with an on-capillary adsorptive phase is investigated for its suitability to quantitate low concentrations of angiotensin II and gonadorelin in plasma. An off-line solid-phase extraction is used for sample preparation. The on-line preconcentration CE system allows multiple capillary volumes of sample solution to be injected, increasing the concentration sensitivity of CE with 3-4 orders of magnitude. Furthermore, possible influence of matrix salts can be ruled out by employing a rinsing step after sample application. Using short-wavelength UV detection, reproducibility and linearity in the low nanomolar range were satisfactory. The capillary could be efficiently regenerated using a programmed between-run rinsing procedure, allowing 20-30 large injections of sample extracts. Coating of the capillary improved the robustness of the method. Mass spectrometric detection via a previously reported sheathless interface increased the selectivity and sensitivity substantially. Recommendations are provided for the sample preparation process, the most critical part of the system. Further purification of the sample is required to allow the loading of larger sample volumes and to optimize the system's robustness. 相似文献