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201.
Background
We recently observed an association of resistance with a certain enteropathogenic Escherichia coli (EPEC) serotypes and identified a conjugative plasmid, similar to plasmid pED208, that was conserved among archival O111:H2/NM and O119:H2 strains of diverse geographical origin. In this study, we sought to determine the prevalence and distribution of this plasmid among a collection of EPEC isolates from Brazil, as well as to study the susceptibilities of these isolates to antimicrobial agents. 相似文献202.
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A karyomorphological comparison of four genera of the tribe Buchnereae and two genera of the tribe Euphrasieae, root parasites of the subfamily Rhinanthoideae of the Scrophulariaceae, is presented along with 12 new chromosome counts. The interphase nuclei are of the simple chromocenter type. Macranthera and Aureolaria have more subtelocentric chromosomes than those of the other genera studied, which indicates higher asymmetric variation in their karyotypes. In all the karyotypes decrease in size from the longest to the shortest chromosomes is gradual. All the species studied show karyotypic heteromorphology and heteromorphic homologous chromosomes. 相似文献
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Yulia Ievskaya Robert L. Z. Hoye Aditya Sadhanala Kevin P. Musselman Judith L. MacManus-Driscoll 《Journal of visualized experiments : JoVE》2016,(113)
Atmospheric pressure spatial atomic layer deposition (AP-SALD) was used to deposit n-type ZnO and Zn1-xMgxO thin films onto p-type thermally oxidized Cu2O substrates outside vacuum at low temperature. The performance of photovoltaic devices featuring atmospherically fabricated ZnO/Cu2O heterojunction was dependent on the conditions of AP-SALD film deposition, namely, the substrate temperature and deposition time, as well as on the Cu2O substrate exposure to oxidizing agents prior to and during the ZnO deposition. Superficial Cu2O to CuO oxidation was identified as a limiting factor to heterojunction quality due to recombination at the ZnO/Cu2O interface. Optimization of AP-SALD conditions as well as keeping Cu2O away from air and moisture in order to minimize Cu2O surface oxidation led to improved device performance. A three-fold increase in the open-circuit voltage (up to 0.65 V) and a two-fold increase in the short-circuit current density produced solar cells with a record 2.2% power conversion efficiency (PCE). This PCE is the highest reported for a Zn1-xMgxO/Cu2O heterojunction formed outside vacuum, which highlights atmospheric pressure spatial ALD as a promising technique for inexpensive and scalable fabrication of Cu2O-based photovoltaics. 相似文献
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Molecular evolution of olfactomedin 总被引:2,自引:0,他引:2
Olfactomedin is a secreted polymeric glycoprotein of unknown function,
originally discovered at the mucociliary surface of the amphibian olfactory
neuroepithelium and subsequently found throughout the mammalian brain. As a
first step toward elucidating the function of olfactomedin, its
phylogenetic history was examined to identify conserved structural motifs.
Such conserved motifs may have functional significance and provide targets
for future mutagenesis studies aimed at establishing the function of this
protein. Previous studies revealed 33% amino acid sequence identity between
rat and frog olfactomedins in their carboxyl terminal segments. Further
analysis, however, reveals more extensive homologies throughout the
molecule. Despite significant sequence divergence, cysteines essential for
homopolymer formation such as the CXC motif near the amino terminus are
conserved, as is the characteristic glycosylation pattern, suggesting that
these posttranslational modifications are essential for function.
Furthermore, evolutionary analysis of a region of 53 amino acids of fish,
frog, rat, mouse, and human olfactomedins indicates that an ancestral
olfactomedin gene arose before the evolution of terrestrial vertebrates and
evolved independently in teleost, amphibian, and mammalian lineages.
Indeed, a distant olfactomedin homolog was identified in Caenorhabditis
elegans. Although the amino acid sequence of this invertebrate protein is
longer and highly divergent compared with its vertebrate homologs, the
protein from C. elegans shows remarkable similarities in terms of conserved
motifs and posttranslational modification sites. Six universally conserved
motifs were identified, and five of these are clustered in the carboxyl
terminal half of the protein. Sequence comparisons indicate that evolution
of the N-terminal half of the molecule involved extensive insertions and
deletions; the C-terminal segment evolved mostly through point mutations,
at least during vertebrate evolution. The widespread occurrence of
olfactomedin among vertebrates and invertebrates underscores the notion
that this protein has a function of universal importance. Furthermore,
extensive modification of its N-terminal half and the acquisition of a
C-terminal SDEL endoplasmic-reticulum- targeting sequence may have enabled
olfactomedin to adopt new functions in the mammalian central nervous
system.
相似文献
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