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291.
292.
Karina Hansen Kjaer Jesper Buchhave Poulsen Tõnu Reintamm Emilie Saby Pia Moeller Martensen Merike Kelve Just Justesen 《Journal of molecular evolution》2009,69(6):612-624
The 2′-5′-oligoadenylate synthetase (OAS) belongs to a nucleotidyl transferase family that includes poly(A) polymerases and
CCA-adding enzymes. In mammals and birds, the OAS functions in the interferon system but it is also present in an active form
in sponges, which are devoid of the interferon system. In view of these observations, we have pursued the idea that OAS genes
could be present in other metazoans and in unicellular organisms as well. We have identified a number of OAS1 genes in annelids,
mollusks, a cnidarian, chordates, and unicellular eukaryotes and also found a family of proteins in bacteria that contains
the five OAS-specific motifs. This indicates a specific relationship to OAS. The wide distribution of the OAS genes has made
it possible to suggest how the OAS1 gene could have evolved from a common ancestor to choanoflagellates and metazoans. Furthermore,
we suggest that the OASL may have evolved from an ancestor of cartilaginous fishes, and that the OAS2 and the OAS3 genes evolved
from a mammalian ancestor. OAS proteins function in the interferon system in mammals. This system is only found in jawed vertebrates.
We therefore suggest that the original function of OAS may differ from its function in the interferon system, and that this
original function of OAS is preserved even in OAS genes that code for proteins, which do not have 2′-5′-oligoadenylate synthetase
activity. 相似文献
293.
Blue-green algae are common in the benthos of Mirror Lake, New Hampshire (U. S. A.) — on macrophytes and on the lake bottom-and are probably responsible for the variable, sometimes high rates of N-fixation that detected by a series of acetylene-reduction assays during September and October. 相似文献
294.
Henry W. Moeller Bradley Bennett Susan Coughlin Donald Getz 《Marine and Freshwater Behaviour and Physiology》2013,45(1-4):257-260
Lemon sharks seized lighted grey snappers before seizing the unlighted but otherwise identical grey snappers in ten consecutive observations. Snappers bearing a light embedded in epoxy resin were approached in a straight line attack pattern while (dark) controls were always circled by the shark at least once before attack and seizure. 相似文献
295.
Ingrid Moeller Anthony L. Albiston Rebecca A. Lew Frederick A. O. Mendelsohn & Siew-Yeen Chai 《Journal of neurochemistry》1999,73(1):301-308
The AT4 receptor was characterized initially as a specific binding site for angiotensin IV, a C-terminal fragment of the vasoactive peptide angiotensin II. Recently, we found that LVV-hemorphin-7, a fragment of beta globin, is an abundant peptide in the brain and binds to the AT4 receptor with high affinity and specificity. In the neuroblastoma/glioma hybrid cell line, NG108-15, LVV-hemorphin-7 and angiotensin IV competed for 125I-angiotensin IV binding in a biphasic fashion with IC50 values of 1.2 x 10(-10) and 1.1 x 10(-9) M for the high-affinity site, respectively, and 6.7 x 10(-8) and 1.5 x 10(-8) M for the low-affinity site, respectively. Both peptides were internalized rapidly by the cells. However, LVV-hemorphin-7, but not angiotensin IV, elicited a 1.8-fold increase in DNA synthesis in a dose-dependent manner. Furthermore, co-incubation of the cells with an excess of angiotensin IV (10(-6) M) inhibited LVV-hemorphin-7-stimulated DNA synthesis. Therefore, whereas LVV-hemorphin-7 and angiotensin IV were capable of binding to the AT4 receptor, only LVV-hemorphin-7 elicited [3H]thymidine incorporation in NG108-15 cells. In contrast, angiotensin IV behaved as an antagonist. The current finding suggests that LVV-hemorphin-7 is a functional peptide in the central nervous system and in view of its abundance in neural tissue, compared with angiotensin IV, may be of significant physiological importance. 相似文献