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51.
Steven R. Hagen Duane LeTourneau Paul Muneta Janice Brown 《Plant Growth Regulation》1990,9(4):341-345
Callus cultures of 7 potato cultivars were initiated from tuber tissue and maintained on Gelrite-solidified media with 1–20 M picloram as the only PGR. Ten M picloram was the optimal concentration for callus induction. By 4–6 weeks after explanting, there was sufficient callus produced for subculture to maintenance media which contained 1–20 M picloram as the only PGR. When grown in the dark at 25°C, subcultured callus typically increased 10-fold in wet weight in 4–5 weeks. The callus produced was friable and a light grey to cream color. Callus cultures were used to establish cell suspension cultures. Callus and cell suspension cultures have been maintained for over 2 years on the picloram containing media.Abbreviations BA
benzyladenine
- 2,4-D
2,4-dichlorophenoxyacetic acid
- MS
Murashige-Skoog
- NAA
naphthaleneacetic acid
- PGR
plant growth regulator
Research paper #9053 of the Idaho Agricultural Experiment Station. 相似文献
52.
Earl F. Albone Fred K. Hagen Claude Szpirer Lawrence A. Tabak 《Glycoconjugate journal》1996,13(5):709-716
Mucin glycoproteins are a major constituent of salivary secretions and play a primary role in the protection of the oral cavity. Rat submandibular glands (RSMG) synthesize and secrete a low molecular weight (114 kDa) mucin glycoprotein. We have isolated, partially sequenced, and characterized the gene which encodes the RSMG apomucin. The gene is encoded by three exons of 106 nt, 69 nt, and 991 nt, separated by introns of 921 nt and 12.5 kb. CAAT and TATA elements are present, at –68 and –26, respectively, in the 5 flanking sequence of the RSMG apomucin gene. The tandem repeat domain present in exon III consists of ten tandem repeats of 39 nt encoding the consensus sequence PTTDSTTPAPTTK. Sequence comparison and organization of the nucleic acid sequence encoding the tandem repeats of two alleles for this gene suggests that the apomucin gene has undergone recombinational events during its evolution. No significant sequence similarity was found with other mucin genes, or with other known salivary gland-specific genes. The gene was localized to rat chromosome 14 using somatic cell hybrids that segregate rat chromosomes. Since this, to our knowledge, represents the first RSMG mucin gene cloned, we have designated this geneMucsmg.Abbreviations RSMG
rat submandibular gland
- RSM
rat salivary mucin
- GRP
glutamine-glutamic-acid rich protein
- nt
nucleotide
- kb
kilobase
Sequences reported herein have been assigned GenBank accession numbers U33441 and U33442. 相似文献
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Excess amino acid polymorphism in mitochondrial DNA: contrasts among genes from Drosophila, mice, and humans 总被引:13,自引:3,他引:10
Recent studies of mitochondrial DNA (mtDNA) variation in mammals and
Drosophila have shown an excess of amino acid variation within species
(replacement polymorphism) relative to the number of silent and replacement
differences fixed between species. To examine further this pattern of
nonneutral mtDNA evolution, we present sequence data for the ND3 and ND5
genes from 59 lines of Drosophila melanogaster and 29 lines of D. simulans.
Of interest are the frequency spectra of silent and replacement
polymorphisms, and potential variation among genes and taxa in the
departures from neutral expectations. The Drosophila ND3 and ND5 data show
no significant excess of replacement polymorphism using the
McDonald-Kreitman test. These data are in contrast to significant
departures from neutrality for the ND3 gene in mammals and other genes in
Drosophila mtDNA (cytochrome b and ATPase 6). Pooled across genes, however,
both Drosophila and human mtDNA show very significant excesses of amino
acid polymorphism. Silent polymorphisms at ND5 show a significantly higher
variance in frequency than replacement polymorphisms, and the latter show a
significant skew toward low frequencies (Tajima's D = -1.954). These
patterns are interpreted in light of the nearly neutral theory where mildly
deleterious amino acid haplotypes are observed as ephemeral variants within
species but do not contribute to divergence. The patterns of polymorphism
and divergence at charge-altering amino acid sites are presented for the
Drosophila ND5 gene to examine the evolution of functionally distinct
mutations. Excess charge-altering polymorphism is observed at the carboxyl
terminal and excess charge-altering divergence is detected at the amino
terminal. While the mildly deleterious model fits as a net effect in the
evolution of nonrecombining mitochondrial genomes, these data suggest that
opposing evolutionary pressures may act on different regions of
mitochondrial genes and genomes.
相似文献
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56.
Evidence for cytosine methylation of non-symmetrical sequences in transgenic Petunia hybrida. 总被引:12,自引:1,他引:11 下载免费PDF全文
A considerable proportion of cytosine residues in plants are methylated at carbon 5. According to a well-accepted rule, cytosine methylation is confined to symmetrical sequences such as CpG and CpNpG, which provide the signal for faithful transmission of symmetrical methylation patterns by maintenance methylase. Using a genomic sequencing technique, we have analysed cytosine methylation patterns within a hypermethylated and a hypomethylated state of a transgene in Petunia hybrida. Examination of a part of the transgene promoter revealed that in both states m5C residues located within non-symmetrical sequences could be detected. Non-symmetrical C residues in the two states were methylated at frequencies of 5.9 and 31.9%, respectively. Methylation appeared to be distributed heterogeneously, but some DNA regions were more intensively methylated than others. Our results show that at least in a transgene, a heterogeneous methylation pattern, which does not depend on symmetry of target sequences, can be established and conserved. 相似文献
57.
Ulrich Hagen 《Radiation and environmental biophysics》1994,33(1):45-61
The various aspects of formation and repair of radiation-induced double-strand breaks (DSB) are summarized. Concerning the structure of DSB found in irradiated cells, enzymatic and microdosimetric analysis hints at complex damage of the DNA structure at the position of a DSB. With increasing LET, the DSB damage may be more complex than that induced by low-LET irradiation. Most of the DSB are repaired in the irradiated cell; apparently the kinetics of DSB repair and the fraction of unrejoined DSB determine cell survival or cell death. We do not know the details of the complex machinery of DSB repair; certaintly recombination processes are involved, but there are still contradictions between our current knowledge about the mechanisms of recombinational DSB repair and the observed kinetics.Dedicated to Prof. W. Jacobi on the occasion of his 65th birthday 相似文献
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