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31.
In an isolated population of Drosophila melanogaster on Ishigaki Island the
chromosomal distribution of several retrotransposons, including copia, 412,
297, 17.6, I, and jockey elements, was examined by in situ hybridization.
In this population the cosmopolitan inversion, In(2L)t, is known to exist
in high frequency. One major haplotype concerning the occupied sites of the
transposable elements was identified in the In(2L)t-carrying chromosomes.
This haplotype is suggested to be the ancestral one. The age of the
inversion in this local population was estimated to be 1,400 generations.
The transposition rates of these elements were estimated based on the age
of the inversion and the number of the elements lost and gained. The
excision rates were in the range from 9.13 x 10(-5) to 2.25 x 10(-4) per
site per generation. They were similar each other in the copia-like
elements as well as in the LINE-like elements. The rate was higher in the
copia-like elements than in the LINE-like elements. Insertions occurred in
the range from 6.79 x 10(-4) to 9.05 x 10(-4) per element per generation.
It is herein shown that both insertions and excisions occurred at a
significantly higher rate in this population than in the laboratory.
相似文献
32.
Two soluble glycosyltransferases glycosylate less efficiently in vivo than their membrane bound counterparts 总被引:2,自引:1,他引:1
Zhu G; Allende ML; Jaskiewicz E; Qian R; Darling DS; Worth CA; Colley KJ; Young WW Jr 《Glycobiology》1998,8(8):831-840
Many Golgi glycosyltransferases are type II membrane proteins which are
cleaved to produce soluble forms that are released from cells. Cho and
Cummings recently reported that a soluble form of alpha1, 3-
galactosyltransferase was comparable to its membrane bound counterpart in
its ability to galactosylate newly synthesized glycoproteins (Cho,S.K. and
Cummings,R.D. (1997) J. Biol. Chem., 272, 13622-13628). To test the
generality of their findings, we compared the activities of the full length
and soluble forms of two such glycosyltransferases, ss1,4
N-Acetylgalactosaminyltransferase (GM2/GD2/ GA2 synthase; GalNAcT) and beta
galactoside alpha2,6 sialyltransferase (alpha2,6-ST; ST6Gal I), for
production of their glycoconjugate products in vivo . Unlike the full
length form of GalNAcT which produced ganglioside GM2 in transfected cells,
soluble GalNAcT did not produce detectable GM2 in vivo even though it
possessed in vitro GalNAcT activity comparable to that of full length
GalNAcT. When compared with cells expressing full length alpha2,6-ST, cells
expressing a soluble form of alpha2,6-ST contained 3-fold higher
alpha2,6-ST mRNA levels and secreted 7-fold greater alpha2,6-ST activity as
measured in vitro , but in striking contrast contained 2- to 4-fold less of
the alpha2,6-linked sialic acid moiety in cellular glycoproteins in vivo .
In summary these results suggest that unlike alpha1,3-galactosyltransferase
the soluble forms of these two glycosyltransferases are less efficient at
glycosylation of membrane proteins and lipids in vivo than their membrane
bound counterparts.
相似文献
33.
Pengchong Li Hao Zou Yudong Ren Dante S. Zarlenga Xiaofeng Ren 《Current microbiology》2014,68(1):82-87
The goal of this study was to evaluate how two new hydrolysates from poultry by-products act on ten lactobacilli growth kinetics when supplemented to the growth medium. These effects were compared with ones induced by two most common commercial hydrolysates, i.e., tryptone and peptone. Growth medium, supplemented with one of new hydrolysates, 78T, as only nitrogen source, can sustain the maximum growth rate and the biomass yield in the same way of MRS, reach of different nitrogen sources. Moreover aminopeptidase activities (AA) of each strain were determined to investigate the effect of the growth condition on the modulation of aminopeptidase pattern. Five cell extracts of each ten strains, obtained from their cultivation in MRS and in the presence of the two common hydrolysates and the two new ones, were considered. AA was investigated against five different chromogenic substrates: β-naphthyl amide derivatives of l-anomers of leucine, lysine, proline, glycine–proline, and phenilalanine–proline. A great variability of AA was observed among the strains: also strains belonging to the same species showed peculiar AA profile. 相似文献
34.
WT Ismaya A Efthyani DS Retnoningrum X Lai BW Dijkstra RR Tjandrawinata 《Biotechnic & histochemistry》2017,92(6):411-416
The light subunit of mushroom, Agaricus bisporus, tyrosinase (LSMT), has been identified as an extrinsic component of the enzyme. Its function is unknown, but it can cross an epithelial cell layer, which suggests that it can be absorbed by the intestine. A similar capability has been demonstrated for the HA-33 component of the progenitor toxin from Clostridium botulinum, which is the closest structural homolog of LSMT. Unlike HA-33, LSMT appears to be non-immunogenic as shown by preliminary tests in Swiss Webster mice. We investigated the immunogenicity and histopathology of LSMT in mice to determine its safety in vivo. LSMT did not evoke generation of antibodies after prolonged periods of intraperitoneal administration. Histopathological observations confirmed the absence of responses in organs after twelve weekly administrations of LSMT. We found that LSMT is not toxic and is less immunogenic than the C. botulinum HA-33 protein, which supports further research and development for pharmaceutical application. 相似文献
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37.
R Martin DS Buchan JS Baker J Young N Sculthorpe FM Grace 《Biology of sport / Institute of Sport》2015,32(4):307-313
The present study examined the physiological impact of a school based sprint interval training (SIT) intervention in replacement of standard physical education (SPE) class on cardio-respiratory fitness (CRF) and glucose homeostasis during the semester following summer vacation. Participants (n=49) were randomly allocated to either intervention (SIT; n=26, aged 16.9 ± 0.3 yrs) or control group who underwent standard physical education (SPE; n=23, aged 16.8 ± 0.6 yrs). CRF (VO2max) and glucose homeostasis were obtained prior-to and following 7 weeks of SIT exercise. Significant group x time interaction was observed for CRF (P < 0.01) with non-significant trends for fasting insulin (P= 0.08), and HOMA-IR (P=0.06). CRF decreased (P < 0.01) in SPE such that POST intervention CRF was significantly lower (P< 0.05) in SPE. Fasting plasma glucose (P < 0.01), insulin (P< 0.01) and HOMA-IR (P< 0.01) increased significantly amongst SPE. The main finding of the present study is that 7-weeks of SIT exercise is an effective method of maintaining (but not improving) CRF and fasting insulin homeostasis amongst school-going adolescents. SIT exercise demonstrates potential as a time efficient physiological adjunct to standard PE class in order to maintain CRF during the school term. 相似文献
38.
Background
There are some early clinical indicators of cardiac ischemia, most notably a change in a person's electrocardiogram. Less well understood, but potentially just as dangerous, is ischemia that develops in the gastrointestinal system. Such ischemia is difficult to diagnose without angiography (an invasive and time-consuming procedure) mainly due to the highly unspecific nature of the disease. 相似文献39.
Don?Simone?DalyEmail author Amanda?M?White Susan?M?Varnum Kevin?K?Anderson Richard?C?Zangar 《BMC bioinformatics》2005,6(1):17
Background
Enzyme-linked immunosorbent assay (ELISA) is a standard immunoassay to estimate a protein's concentration in a sample. Deploying ELISA in a microarray format permits simultaneous estimation of the concentrations of numerous proteins in a small sample. These estimates, however, are uncertain due to processing error and biological variability. Evaluating estimation error is critical to interpreting biological significance and improving the ELISA microarray process. Estimation error evaluation must be automated to realize a reliable high-throughput ELISA microarray system. 相似文献40.
A set of large positive extrinsic CD bands ([θ]333 = 2.6 X 104 deg-cm2/decimole phosphate) in the > 300 nm region as well as diminution of the intrinsic signals (θ275) have been observed in the CD spectra of various nucleic acids complexed with the achiral compound, N-poly{α-[N-(4-pyridylethylene-4-pyridyl-N′-)α′-p-xylyl]dibromide}-4-pyridylethylene-4-pyridinium bromide, (polymer X).1,2,5 The signal changes are attributed to the binding of polymer X chromophores isogeometrically to the DNA helix in an ordered chiral arrangement. Fractionation of polymer X gives 10 well-separated oligomers. The oligomers were characterized by nmr. Their interactions with DNA have been investigated with respect to r(r = ratio of equivalents of polymer X charge/g-atoms DNA phosphorus) and n (oligomer chain length). In all cases where n ≥ 1, [θ]333 increases linearly with increasing r between 0 and 0.32, and is accompanied by a corresponding decrease in [θ]275, which becomes negative as r approaches .32. Extrinsic band intensities reveal a dependence on n up to n = 5, above which increases in nonspecific binding result in a reduction in normalized band intensities. Polymer X shows a strong preference for B-form nucleic acids and induces maximum extrinsic CD signal intensities with A-T homopolymers. Alterations in helix hydration are believed to accompany complex formation. Inversions in [θ]275 of the octamer X-poly(dA-dT) complex have been attributed to the “alternating B” conformation of poly(dA-dT).3 Similar inversions are not observed in other nucleic acid-octamer X complexes. Visible and CD spectrometry data from competition studies in the presence of the antibiotics actinomycin D (AMD), daunomycin (DM), and distamycin A (DST) are consistent with “nonclassical” intercalation as the mode of binding, and these data place the potential binding site in or near the hydrophobic region of the minor groove. Reductions in [θ]333 with increasing urea further implicate the involvement of hydrophobic interactions in the formation of an asymmetric complex. Stabilization of the helix results in all cases as evidenced by alterations in Tm; corresponding changes, however, in cooperativity are not clearly discernable. Viscosity and light-scattering data indicate no changes in molecular weight due to aggregation, and as such are not consistent with a transition to the ψ-DNA upon complex formation. 相似文献