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81.
KEEGANACHSAHD JOSEZAMORAN 《Cell research》1998,8(1):1-13
Interleukin-4 is a cytokine produced by activated T cells,mast cells,and basophils that elicits many important biological responses[1](see Tab 1).These responses range from the regulation of helper T cell differentiation[2] and the production of IgE[3] to the regulation of the adhesive properties of endothelial cells via VCAM-1[4],In keeping with these diverse biological effects,high-affinity binding sites for IL-4(Kd 20 to 300pM) have been detected on many hematopoietic and non-hematopoietic cell types at levels ranging from 50 to 5000 sites per cell[5].This review will focus on the discrete signal transduction pathways activated by the IL-4 recxeptor and the coordination of these individual pathways in the regulation of a final biological outcome. 相似文献
82.
ENRIQUE E. MONTAMAT SANDRA DURAND JOSE L. BOCCO GLORIA M. DE LUCA D'ORO ANTONIO BLANCO 《The Journal of eukaryotic microbiology》1999,46(2):155-159
Analysis of zymograms of extracts of Trypanosoma cruzi isolated from different hosts in Argentina allowed characterization of 12 zymodemes or "isozymic strains," only six of which were found in human patients. Two of these six zymodemes (Z1 and Z12) were widely distributed and found in more than 80% of human patients. These two "major natural clones" differed significantly in pathogenic activity. Because the groupings obtained by studying enzymes and kinetoplast DNA (kDNA) were similar, it is possible to identify the zymodeme by analyzing kDNA. A 290-bp fragment was amplified by PCR using primers for the sequences flanking the hypervariable regions of kDNA minicircles. Labeled probes for this fragment, prepared from Z1 and Z12 reference stocks, hybridized specifically with PCR-amplified kDNA from parasite stocks, allowing identification of zymodemes. 相似文献
83.
CHRISTOPHER B. ANDERSON JUAN L. CELIS‐DIEZ BARBARA J. BOND GUILLERMO MARTÍNEZ PASTUR CHRISTIAN LITTLE JUAN J. ARMESTO CLAUDIO GHERSA AMY AUSTIN TOMAS SCHLICHTER ANTONIO LARA MARTIN CARMONA ENRIQUE J. CHANETON JULIO R. GUTIERREZ RICARDO ROZZI KRISTIN VANDERBILT GUILLERMO OYARCE ROBERTO J. FERNÁNDEZ 《Austral ecology》2012,37(5):529-536
84.
CAROLIN A. REBERNIG GERALD M. SCHNEEWEISS KATHARINA E. BARDY PETER SCHÖNSWETTER JOSE L. VILLASEÑOR RENATE OBERMAYER TOD F. STUESSY HANNA WEISS‐SCHNEEWEISS 《Molecular ecology》2010,19(16):3421-3443
Pleistocene climatic fluctuations had major impacts on desert biota in southwestern North America. During cooler and wetter periods, drought‐adapted species were isolated into refugia, in contrast to expansion of their ranges during the massive aridification in the Holocene. Here, we use Melampodium leucanthum (Asteraceae), a species of the North American desert and semi‐desert regions, to investigate the impact of major aridification in southwestern North America on phylogeography and evolution in a widespread and abundant drought‐adapted plant species. The evidence for three separate Pleistocene refugia at different time levels suggests that this species responded to the Quaternary climatic oscillations in a cyclic manner. In the Holocene, once differentiated lineages came into secondary contact and intermixed, but these range expansions did not follow the eastwardly progressing aridification, but instead occurred independently out of separate Pleistocene refugia. As found in other desert biota, the Continental Divide has acted as a major migration barrier for M. leucanthum since the Pleistocene. Despite being geographically restricted to the eastern part of the species’ distribution, autotetraploids in M. leucanthum originated multiple times and do not form a genetically cohesive group. 相似文献
85.
JOSE MARÍA GABRIEL Y GALÁN GIULIANA MIGLIARO RAFAEL LAHOZ‐BELTRÁ 《Plant Species Biology》2011,26(3):254-258
To study the influence of temperature on the germination ability of three species of Jamesonia (Jamesonia imbricata, Jamesonia scammaniae and Jamesonia rotundifolia), spores were cultured at 10°C, 15°C and 20°C. A temperature of 15°C was selected as representative of the natural annual average temperature of the paramo environment that Jamesonia species inhabit. In addition, a dark pretreatment of 2 days was tested to verify if germination was enhanced. The results indicated that germination of Jamesonia, considering the three species as a whole, is affected by temperature, but is independent of the dark treatment. All species showed higher and faster germination at 20°C, and exhibited a threshold minimum temperature around 10°C, below which germination is avoided or extremely low and delayed. This could suggest that spore germination in Jamesonia is adapted to establish gametophyte populations during frost‐free periods. 相似文献
86.
R. EDUARDO PALMA ENRIQUE RODRÍGUEZ‐SERRANO ERIC RIVERA‐MILLA CRISTIAN E. HERNANDEZ JORGE SALAZAR‐BRAVO MARIA I. CARMA SEBASTIAN BELMAR‐LUCERO PABLO GUTIERREZ‐TAPIA HORACIO ZEBALLOS TERRY L. YATES 《Zoological Journal of the Linnean Society》2010,160(3):551-566
Sequences from two mitochondrial genes (cytochrome b and NADH1) were used to produce a molecular phylogeny for 12 named and two undescribed species of the genus Oligoryzomys. All analyses placed Oligoryzomys microtis as the most basal taxon, a finding consistent with previous studies that suggested the west‐central Amazon as a centre of origin for the tribe Oryzomyini to which Oligoryzomys belongs. Biogeographically, this suggests that Oligoryzomys had a South American origin, and later advanced northwards, entering Central America and Mexico more recently. Different analyses have provided consistent support for several additional clades that did not necessarily agree with the species groups hypothesized by previous studies. A molecular clock derived for these data suggests an origin for the genus of 6.67 Mya, with most speciation within the genus occurring between 3.7 and 1.5 Mya. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 551–566. 相似文献
87.
MANUEL JOSE GIL ESTEVES ARNALDO FEITOSA BRAGA ANDRADE CELUTA SALES ALVIANO ISAAC ROITMAN WANDERLEY DE SOUZA JAYME ANGLUSTER 《The Journal of eukaryotic microbiology》1987,34(2):226-230
Wild type Crithidia fasciculata and three drug-resistant mutant strains that have shown “flagellar adherence” were studied as to their ability to agglutinate with lectins specific for receptor molecules containing N-acetyl glucosamine, N-acetyl galactosamine, galactose, mannose-like residues, fucose, and sialic acid. Escherichia coli with mannose-sensitive fimbriae was also used as an agglutination probe. The presence of D-GalNAc, D-Gal, and mannose-like residues was detected in the wild strain. Generally, in the mutants, residues of these sugar units were present in greater concentrations when compared to the wild type strain. β-Galactosidase treatment showed that β-D-Galp units are exposed on the cell membrane. All types of cell agglutination including flagellum-flagellum (F-F), flagellum-soma (F-S), and soma-soma (S-S) were observed when lectins were used; however, with E. coli only the F-F type of cell agglutination was observed with the wild type strain and the TFRR1 mutant. All types of agglutination were observed with the other two mutants. 相似文献
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90.
Numbers and characteristics of lactate-utilizing organisms in the rumen of cattle 总被引:5,自引:0,他引:5 下载免费PDF全文
GUTIERREZ J 《Journal of bacteriology》1953,66(2):123-128