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Phylogeny can be used to make useful predictions of soil-to-plant transfer factors for radionuclides
Neil J. Willey 《Radiation and environmental biophysics》2010,49(4):613-623
Soil-to-plant transfer of radionuclides can be related to plant evolutionary history (phylogeny). For some species and radionuclides
the effect is significant enough to be useful in predicting Transfer Factors (TFs). Here a Residual Maximum Likelihood (REML)-based
mixed model and a recent plant phylogeny are used to compile data on soil-to-plant transfer of radionuclides and to show how
the phylogeny can be used to fill gaps in TFs. Using published data, generic means for TFs are used to anchor the data from
REML modelling and hence predict TFs for important groups of plants. Radionuclides of Cs are used as an example. With a generic
soil-to-plant TF of 0.07, TFs of 0.035 and 0.085 are predicted for monocot and eudicot gaps, respectively. Also demonstrated
is how the known effects of soil conditions can be predicted across plant groups—predicted Cs TFs for gap-filling across all
flowering plants are calculated for sandy loams with and without waterlogging. Predictions of TFs for Sr, Co, Cl and Ru are
also given. Overall, the results show that general predictions of TFs based on phylogeny are possible—a significant contribution
to gap filling for TFs. 相似文献
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The green, phototrophic euglenoid, Colacium libellae, has a vestigial cytostome and cytopharynx. The membrane forming the simple pocket is decorated with a dense, microfilamentous mesh. The mesh binds the pocket to a band of reinforcing microtubules which is homologous with the bodonid MTR. The opening of the cytostome at the reservoir-canal transition zone implies that the phototrophic euglenoid canal is formed by the invagination of the vestibulum of the phagotrophic euglenoids. Our observations support the hypothesis that the phagotrophic euglenoids arose from a bondonid ancestor and gave rise to the phototrophs by chloroplast acquisition. 相似文献
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Alvaro CD Faria Agnaldo J Lopes José M Jansen Pedro L Melo 《Biomedical engineering online》2009,8(1):22-10
Background
Early detection of the effects of smoking is of the utmost importance in the prevention of chronic obstructive pulmonary disease (COPD). The forced oscillation technique (FOT) is easy to perform since it requires only tidal breathing and offers a detailed approach to investigate the mechanical properties of the respiratory system. The FOT was recently suggested as an attractive alternative for diagnosing initial obstruction in COPD, which may be helpful in detecting COPD in its initial phases. Thus, the purpose of this study was twofold: (1) to evaluate the ability of FOT to detect early smoking-induced respiratory alterations; and (2) to compare the sensitivity of FOT with spirometry in a sample of low tobacco-dose subjects. 相似文献226.
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Noncontact dipole effects on channel permeation. III. Anomalous proton conductance effects in gramicidin 总被引:3,自引:2,他引:1 下载免费PDF全文
LR Phillips CD Cole RJ Hendershot M Cotten TA Cross DD Busath 《Biophysical journal》1999,77(5):2492-2501
Proton transport on water wires, of interest for many problems in membrane biology, is analyzed in side-chain analogs of gramicidin A channels. In symmetrical 0.1 N HCl solutions, fluorination of channel Trp(11), Trp-(13), or Trp(15) side chains is found to inhibit proton transport, and replacement of one or more Trps with Phe enhances proton transport, the opposite of the effects on K(+) transport in lecithin bilayers. The current-voltage relations are superlinear, indicating that some membrane field-dependent process is rate limiting. The interfacial dipole effects are usually assumed to affect the rate of cation translocation across the channel. For proton conductance, however, water reorientation after proton translocation is anticipated to be rate limiting. We propose that the findings reported here are most readily interpreted as the result of dipole-dipole interactions between channel waters and polar side chains or lipid headgroups. In particular, if reorientation of the water column begins with the water nearest the channel exit, this hypothesis explains the negative impact of fluorination and the positive impact of headgroup dipole on proton conductance. 相似文献
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