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41.
Numerous transposed sequences of mitochondrial cytochrome oxidase I-II in aphids of the genus Sitobion (Hemiptera: Aphididae) 总被引:4,自引:1,他引:3
Polymerase chain reaction (PCR) products corresponding to 803 bp of the
cytochrome oxidase subunits I and II region of mitochondrial DNA (mtDNA
COI-II) were deduced to consist of multiple haplotypes in three Sitobion
species. We investigated the molecular basis of these observations. PCR
products were cloned, and six clones from one individual per species were
sequenced. In each individual, one sequence was found commonly, but also
two or three divergent sequences were seen. The divergent sequences were
shown to be nonmitochondrial by sequencing from purified mtDNA and Southern
blotting experiments. All seven nonmitochondrial clones sequenced to
completion were unique. Nonmitochondrial sequences have a high proportion
of unique sites, and very few characters are shared between
nonmitochondrial clones to the exclusion of mtDNA. From these data, we
infer that fragments of mtDNA have been transposed separately (probably
into aphid chromosomes), at a frequency only known to be equalled in
humans. The transposition phenomenon appears to occur infrequently or not
at all in closely related genera and other aphids investigated. Patterns of
nucleotide substitution in mtDNA inferred over a parsimony tree are very
different from those in transposed sequences. Compared with mtDNA,
nonmitochondrial sequences have less codon position bias, more even
exchanges between A, G, C and T, and a higher proportion of nonsynonymous
replacements. Although these data are consistent with the transposed
sequences being under less constraint than mtDNA, changes in the
nonmitochondrial sequences are not random: there remains significant
position bias, and probable excesses of synonymous replacements and of
conservative inferred amino acid replacements. We conclude that a
proportion of the inferred change in the nonmitochondrial sequences
occurred before transposition. We believe that Sitobion aphids (and other
species exhibiting mtDNA transposition) may be important for studying the
molecular evolution of mtDNA and pseudogenes. However, our data highlight
the need to establish the true evolutionary relationships between sequences
in comparative investigations.
相似文献
42.
J B Moffat 《Journal of theoretical biology》1973,40(2):247-258
The energy surface resulting from the protonation of the peptide unit, OCNH, has been calculated non-empirically using the LCAO MO SCF (Gaussian function) method. Providing that rotation of the NH2+ group is permitted, N-protonation is favoured. However a nearly equal energy minimum was obtained for O-protonation, suggesting that when rotation is not permitted, or when two hydrogens are originally present, O-protonation is favoured. 相似文献
43.
Evaluation of Miniature Test for Bacteriuria Using Dehydrated Media and Nitrite Pads 总被引:2,自引:0,他引:2 下载免费PDF全文
A new dip-inoculum method for detecting bacteriuria which utilizes dehydrated media pads and a nitrite pad attached to a small plastic strip was evaluated in hospitalized patients. Discrepant interpretations were made by independent observers in 9.3% of the specimens with > 10(5) colonies per ml. The media pads failed to support growth of yeast and gave variable results with Staphylococcus epidermidis and non-group D streptococci. False-negative culture results commonly occurred if the patients were receiving antibiotics. The nitrite test occasionally remained positive for brief periods after the elimination of bacteriuria by antibiotics. Conditions and drugs (especially phenazopyridine) which discolor urine interfered with reading both the culture and nitrite tests. Although not suitable for hospital use, or for monitoring therapy, the test strip is probably as reliable as the calibrated loop-streak plate culture for office screening. 相似文献
44.
Ellwood SR Liu Z Syme RA Lai Z Hane JK Keiper F Moffat CS Oliver RP Friesen TL 《Genome biology》2010,11(11):R109
Background
Pyrenophora teres f. teres is a necrotrophic fungal pathogen and the cause of one of barley's most important diseases, net form of net blotch. Here we report the first genome assembly for this species based solely on short Solexa sequencing reads of isolate 0-1. The assembly was validated by comparison to BAC sequences, ESTs, orthologous genes and by PCR, and complemented by cytogenetic karyotyping and the first genome-wide genetic map for P. teres f. teres. 相似文献45.
A functionally conserved Zn2Cys6 binuclear cluster transcription factor class regulates necrotrophic effector gene expression and host‐specific virulence of two major Pleosporales fungal pathogens of wheat 下载免费PDF全文
46.
SnapShot: High-throughput sequencing applications 总被引:1,自引:0,他引:1
47.
Anderson S Srajer V Pahl R Rajagopal S Schotte F Anfinrud P Wulff M Moffat K 《Structure (London, England : 1993)》2004,12(6):1039-1045
We use time-resolved crystallography to observe the structural progression of a bacterial blue light photoreceptor throughout its photocycle. Data were collected from 10 ns to 100 ms after photoactivation of the E46Q mutant of photoactive yellow protein. Refinement of transient chromophore conformations shows that the spectroscopically distinct intermediates are formed via progressive disruption of the hydrogen bond network to the chromophore. Although structural change occurs within a few nanoseconds on and around the chromophore, it takes milliseconds for a distinct pattern of tertiary structural change to fully progress through the entire molecule, thus generating the putative signaling state. Remarkably, the coupling between the chromophore conformation and the tertiary structure of this small protein is not tight: there are leads and lags between changes in the conformation of the chromophore and the protein tertiary structure. 相似文献
48.
Placental Transfer of a Fully Human IgG2 Monoclonal Antibody in the Cynomolgus Monkey,Rat, and Rabbit: A Comparative Assessment from during Organogenesis to Late Gestation 下载免费PDF全文
Graeme J. Moffat Marc W. Retter Gayle Kwon Mark Loomis M. Benjamin Hock Colin Hall Jeanine Bussiere Elise M. Lewis Gary J. Chellman 《Birth defects research. Part B, Developmental and reproductive toxicology》2014,101(2):178-188
Understanding species differences in the placental transfer of monoclonal antibodies is important to inform species selection for nonclinical safety assessment, interpret embryo‐fetal changes observed in these studies, and extrapolate their human relevance. Data presented here for a fully human immunoglobulin G2 monoclonal antibody (IgG2X) revealed that, during organogenesis, in both the cynomolgus monkey (gestation day 35 [gd35]) and the rat (gd10) the extent of IgG2X placental transfer (approximately 0.5% maternal plasma concentration, MPC) was similar to the limited published human data for endogenous IgG. At this early gestational stage, IgG2X placental transfer was approximately 6‐fold higher in the rabbit (gd10). By the end of organogenesis, rat embryonic plasma concentrations (gd16) exceeded those in the cynomolgus monkey (gd50) by approximately 3‐fold. These data suggest that relative to the cynomolgus monkey, the rabbit (and to a lesser extent the rat) may overestimate potential harmful effects to the human embryo during this critical period of development. Beyond organogenesis, fetal IgG2X plasma concentrations increased approximately 10‐fold early in the second trimester (gd50–70) in the cynomolgus monkey and remained relatively unchanged thereafter (at approximately 5% MPC). Late gestational assessment was precluded in rabbits due to immunogenicity, but in rats, fetal IgG2X plasma concentrations increased more than 6‐fold from gd16 to gd21 (reaching approximately 15% MPC). In rats, maternal exposure consistent with that achieved by ICH S6(R1) high‐dose selection criteria resulted in embryonic plasma concentrations, reaching pharmacologically relevant levels during organogenesis. Furthermore, dose proportional exposure in both mothers and embryos indicated that this was unlikely to occur at the lower therapeutic dose levels used in humans 相似文献
49.
Frederick L. Moffat Tieran Han Zhi-Ming Li Michael D. Peck Wenche Jy Yeon S. Ahn Arthur J. Chu Lilly Y. W. Bourguignon 《Journal of cellular physiology》1996,168(1):26-33
That L-arginine (L-Arg) augments the host response to acute bacterial sepsis suggests that this amino acid intervenes early in the immune response, perhaps via the nitric oxide synthetase (NOS) pathway. The effect of L-Arg supplementation on in vitro phagocytosis of fluorescein-labeled, heat-killed Staphylococcus aureus by peripheral blood neutrophils (PMNs) from 12 normal human volunteers was studied. Separated PMNs were incubated for 2 h with labeled bacteria, with and without supplemental L-Arg, D-arginine, glycine, and/or the NOS inhibitors L-canavanine, aminoguanidine, or L-NG-nitroarginine methyl ester. PMNs were fixed and extracellular fluorescence quenched with crystal violet. By flow cytometry and confocal microscopy, L-Arg supplementation was shown to result in a highly significant increase in PMN bacterial phagocytosis, the maximal effect being seen with L-Arg 380 μM and falling off with higher concentrations. This augmentation was completely abrogated by NOS inhibitors in molar excess, but inhibitors alone did not suppress phagocytosis below that of unsupplemented controls. Neither D-arginine nor glycine affected phagocytosis; the L-Arg effect was stereospecific and not related to utilization of L-Arg as an energy source. L-Arg supplementation significantly enhances bacterial phagocytosis in human neutrophils, perhaps by effects on cytoskeletal phenomena, and this appears to be mediated through NOS activity. Phagocytosis by nonspecific immune cells which intervene early in the response to sepsis is critically important, and beneficial effects of L-Arg on the clinical course of sepsis may be due at least in part to augmentation of phagocyte function. © 1996 Wiley-Liss, Inc. 相似文献