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101.
Paternally inherited effects of gamma radiation on mouse preimplantation development detected by the chimera assay 总被引:4,自引:0,他引:4
It has previously been shown that type B spermatogonia in male mice treated with 0.05 Gy of X rays undergo an alteration expressed by progeny embryos as a cellular proliferation disadvantage in a chimera assay. We wished to obtain information on the assay's detection limit to ionizing radiation and on the radiosensitive target in male germ cells. Male mice were briefly irradiated with 137Cs gamma rays at nominal absorbed doses of 0.0, 0.0015, 0.005, 0.010, or 0.05 Gy and then mated for the next 8 weeks to untreated females. Four-cell embryos from treated males (experimental embryos) were paired with FITC-labeled embryos from untreated males (control embryos) to form aggregation chimeras. The chimeras were cultured for 30-40 h and examined under phase-contrast and UV illumination for the number of unlabeled cells (from the experimental embryo) and total chimera cell number, which were then expressed as "proliferation ratios" (No. unlabeled cells/total chimera cell No.). Significant decreases in proliferation ratios were observed at postirradiation weeks 4, 6, and 7 for the 0.01-Gy dose group and at weeks 5-6 for the 0.05-Gy dose group. In addition, significantly lower ratios were observed with early and mid four-cell embryos, but not with late four-cell embryos. These results suggest that mouse male germ cells express a radiosensitive target(s) whose detection limit by the assay lies at an absorbed dose between 0.005 and 0.010 Gy for brief gamma irradiation and whose effect on embryonic cell proliferation might decay by the second cleavage. 相似文献
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104.
Preferential binding of a stable G3BP ribonucleoprotein complex to intron‐retaining transcripts in mouse brain and modulation of their expression in the cerebellum 下载免费PDF全文
105.
TD Smith KP Bhatnagar CJ Bonar KL Shimp MP Mooney MI Siegel 《American journal of physical anthropology》2003,122(3):301-301
106.
J.-R. Martin T. Raabe M. Heisenberg 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1999,185(3):277-288
In Drosophila melanogaster, former studies based on structural brain mutants have suggested that the central complex is a higher control center of locomotor
behavior. Continuing this investigation we studied the effect of the central complex on the temporal structure of spontaneous
locomotor activity in the time domain of a few hours. In an attempt to dissect the internal circuitry of the central complex
we perturbed a putative local neuronal network connecting the four neuropil regions of the central complex, the protocerebral
bridge, the fan-shape body, the noduli and the ellipsoid body. Two independent and non-invasive methods were applied: mutations
affecting the neuroarchitecture of the protocerebral bridge, and the targeted expression of tetanus toxin in small subsets
of central complex neurons using the binary enhancer trap P[GAL4] system. All groups of flies with a disturbed component of
this network exhibited a common phenotype: a drastic decrease in locomotor activity. While locomotor activity was still clustered
in bouts and these were initiated at the normal rate, their duration was reduced. This finding suggests that the bridge and
some of its neural connections to the other neuropil regions of the central complex are required for the maintenance but not
the initiation of walking.
Accepted: 21 June 1999 相似文献
107.
An earlier experimental study carried out by us revealed an increase in intrafemoral pressure during removal of cement in hip revision arthroplasty. This increase is greater while removing cement from the distal femoral shaft. Maximum pressure increases occurred while removing the medullary plug (cement stopper), and the measured pressure of more than 150 mmHg is associated with an increased risk of fat embolism. The present study shows that this phenomenon can be avoided through the use of cannulated instruments. 相似文献
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Stephan Wnendt Michael Finkam Werner Winter Joachim Ossig Gerd Raabe Kai Zwingenberger 《Chirality》1996,8(5):390-396
The question whether the immunomodulating activity of rac-thalidomide resides in either the (−)-(S)- or the (+)-(R)-enantiomer was addressed by synthesis and separation of pure enantiomers of thalidomide-analogues which carry a methyl-group at the asymmetric carbon atom and are thus prevented from racemization. The effect of the pure enantiomers of the thalidomide-analogues and also of the enantiomers of thalidomide on relapse of TNF-α was tested in vitro by using stimulated peripheral mononuclear blood cells. Both enantiomers of thalidomide inhibited the release of TNF-α equally well at low concentrations (5 and 12.5 μg/ml) but at higher concentrations (25 and 50 μg/ml) there was a weak but statistically significant selectivity towards the (−)-(S)-enantiomer. In the case of the configuration-stable thalidomide-analogues there was a very pronounced and statistically significant enantioselectivity towards the (S)-form even at lower concentrations (≥5 μg/ml). The (S)-enantiomers of the thalidomide-analogues differed in their inhibitory potency from (−)-(S)-thalidomide suggesting that the introduction of the methyl-group increases the TNF-α-inhibitory activity while the reduction of one of the carbonyl-functions in the glutarimide-moiety to a methylene-group decreases activity. The effect of these small molecular alterations on activity and the enantioselectivity towards the (S)-enantiomers may indicate that thalidomide and its analogues directly interact with one or several cellular target-proteins. © 1996 Wiley-Liss, Inc. 相似文献
110.