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71.
Takagi Y Akada R Kumagai H Yamamoto K Tamaki H 《Applied microbiology and biotechnology》2008,77(5):1073-1082
Candida albicans is a human fungal pathogen and has been extensively studied because of its clinical importance. Comprehensive gene analyses
have, however, made little progress. This is because of the diploid and asexual characteristics of the fungus that hamper
gene disruptions. In this study, we found that ultraviolet (UV) irradiation, as well as mutagen treatment, strongly stimulated
loss of heterozygosity (LOH) in strains harboring artificially constructed heterozygosity. UV-induced LOH occurred more frequently
in cells within the logarithmic phase of growth compared to those within the stationary phase of growth. This was observed
at all loci tested on chromosome 7, except for a locus neighboring the centromere. C. albicans RAD52, whose orthologue in Saccharomyces cerevisiae was reported to be involved in DNA repair by homologous recombination, was shown to be required for UV-induced LOH. These
results suggest that high efficiency LOH caused by UV irradiation could be a prominent tool for gene analyses in C. albicans. 相似文献
72.
The life cycle of calicivirus is not fully understood because most of the viruses cannot be propagated in tissue culture cells. We studied the mechanism of calicivirus entry into cells using feline calicivirus (FCV), a cultivable calicivirus. From the cDNA library of Crandell-Rees feline kidney (CRFK) cells, feline junctional adhesion molecule 1 (JAM-1), an immunoglobulin-like protein present in tight junctions, was identified as a cellular-binding molecule of the FCV F4 strain, a prototype strain in Japan. Feline JAM-1 expression in nonpermissive hamster lung cells led to binding and infection by F4 and all other strains tested. An anti-feline JAM-1 antibody reduced the binding of FCV to permissive CRFK cells and strongly suppressed the cytopathic effect (CPE) and FCV progeny production in infected cells. Some strains of FCV, such as F4 and F25, have the ability to replicate in Vero cells. We found that regardless of replication ability, FCV bound to Vero and 293T cells via simian and human JAM-1, respectively. In Vero cells, an anti-human JAM-1 antibody inhibited binding, CPE, and progeny production by F4 and F25. In addition, feline JAM-1 expression permitted FCV infection in 293T cells. Taken together, our results demonstrate that feline JAM-1 is a functional receptor for FCV, simian JAM-1 also functions as a receptor for some strains of FCV, and the interaction between FCV and JAM-1 molecules may be a determinant of viral tropism. This is the first report concerning a functional receptor for the viruses in the family Caliciviridae. 相似文献
73.
Early development, pattern, and reorganization of the planula nervous system in Aurelia (Cnidaria, Scyphozoa) 总被引:2,自引:1,他引:1
We examined the development of the nervous system in Aurelia (Cnidaria, Scyphozoa) from the early planula to the polyp stage using confocal and transmission electron microscopy. Fluorescently
labeled anti-FMRFamide, antitaurine, and antityrosinated tubulin antibodies were used to visualize the nervous system. The
first detectable FMRFamide-like immunoreactivity occurs in a narrow circumferential belt toward the anterior/aboral end of
the ectoderm in the early planula. As the planula matures, the FMRFamide-immunoreactive cells send horizontal processes (i.e.,
neurites) basally along the longitudinal axis. Neurites extend both anteriorly/aborally and posteriorly/orally, but the preference
is for anterior neurite extension, and neurites converge to form a plexus at the aboral/anterior end at the base of the ectoderm.
In the mature planula, a subset of cells in the apical organ at the anterior/aboral pole begins to show FMRFamide-like and
taurine-like immunoreactivity, suggesting a sensory function of the apical organ. During metamorphosis, FMRFamide-like immunoreactivity
diminishes in the ectoderm but begins to occur in the degenerating primary endoderm, indicating that degenerating FMRFamide-immunoreactive
neurons are taken up by the primary endoderm. FMRFamide-like expression reappears in the ectoderm of the oral disc and the
tentacle anlagen of the growing polyp, indicating metamorphosis-associated restructuring of the nervous system. These observations
are discussed in the context of metazoan nervous system evolution. 相似文献
74.
Embryonic development and metamorphosis of the scyphozoan <Emphasis Type="Italic">Aurelia</Emphasis> 总被引:2,自引:1,他引:1
We investigated the development of Aurelia (Cnidaria, Scyphozoa) during embryogenesis and metamorphosis into a polyp, using antibody markers combined with confocal
and transmission electron microscopy. Early embryos form actively proliferating coeloblastulae. Invagination is observed during
gastrulation. In the planula, (1) the ectoderm is pseudostratified with densely packed nuclei arranged in a superficial and
a deep stratum, (2) the aboral pole consists of elongated ectodermal cells with basally located nuclei forming an apical organ,
which is previously only known from anthozoan planulae, (3) endodermal cells are large and highly vacuolated, and (4) FMRFamide-immunoreactive
nerve cells are found exclusively in the ectoderm of the aboral region. During metamorphosis into a polyp, cells in the planula
endoderm, but not in the ectoderm, become strongly caspase 3 immunoreactive, suggesting that the planula endoderm, in part
or in its entirety, undergoes apoptosis during metamorphosis. The polyp endoderm seems to be derived from the planula ectoderm
in Aurelia, implicating the occurrence of “secondary” gastrulation during early metamorphosis. 相似文献
75.
In plants, there are no DNA polymerase β (Pol β) and DNA ligase III (Lig3) genes. Thus, the plant short-patch base excision
repair (short-patch BER) pathway must differ considerably from that in mammals. We characterized the rice (Oryza Sativa L. cv. Nipponbare) homologue of the mammalian X-ray repair cross complementing 1 (XRCC1), a well-known BER protein. The plant
XRCC1 lacks the N-terminal domain (NTD) which is required for Pol β binding and is essential for mammalian cell survival.
The recombinant rice XRCC1 (OsXRCC1) protein binds single-stranded DNA (ssDNA) as well as double-stranded DNA (dsDNA) and
also interacts with rice proliferating cell nuclear antigen (OsPCNA) in a pull-down assay. Through immunoprecipitation, we
demonstrated that OsXRCC1 forms a complex with PCNA in vivo. OsXRCC1 mRNA was expressed in all rice organs and was induced by application of bleomycin, but not of MMS, H2O2 or UV-B. Bleomycin also increased the fraction of OsXRCC1 associated with chromatin. These results suggest that OsXRCC1 contributes
to DNA repair pathways that differ from the mammalian BER system. 相似文献
76.
Jin-ichi Ito Yuko Nagayasu Koichi Kato Ryuichiro Sato Shinji Yokoyama 《The Journal of biological chemistry》2002,277(10):7929-7935
Intercellular cholesterol transport in the brain is carried by high density lipoprotein (HDL) generated in situ by cellular interaction with the apolipoprotein apoE, which is mainly synthesized by astrocytes, and with apoA-I secreted by cells such as endothelial cells. Rat astrocytes in fact generate HDL with extracellular apoA-I in addition to releasing HDL with endogenously synthesized apoE, seemingly by the same mechanism as the HDL assembly for systemic circulation. Relating to this reaction, apoA-I induced translocation of newly synthesized cholesterol and phospholipid to the cytosol prior to extracellular assembly of HDL, accompanied by an increase of caveolin-1 in the cytosol, activation of sterol regulatory element-binding protein, and enhancement of cholesterol synthesis. The lipid translocated into the cytosol was recovered in the fraction with a density of 1.09-1.16 g/ml as well as caveolin-1 and cyclophilin A. Cyclosporin A inhibited these apoA-I-mediated reactions and suppressed apoA-I-mediated cholesterol release. The findings suggest that such translocation of cholesterol and phospholipid into the cytosol is related to the apo A-I-mediated HDL assembly in astrocytes through functional association with caveolin-1 and a cyclosporin A-sensitive cyclophilin protein(s). 相似文献
77.
78.
Jun-ichi Kato Yukinobu Nishimura Hideho Suzuki 《Molecular & general genetics : MGG》1989,217(1):178-181
Summary A thermosensitive (ts) parA mutant, MFT110, of Escherichia coli carried at least two ts mutations. The major ts defect, resulting from a mutation mapped originally at 95 min and complemented by pLC8-47, was most probably due to psd. A plasmid carrying the 1.6 kb BamHI-PvuII fragment recloned from pLC8-47 complemented the major ts mutation in MFT110 and psd(ts) in two mutants, but did not correct the Par phenotype of MFT110. The second ts mutation was salt-repairable and mapped at 83 min close to recF and tnaA. This mutation was linked with the Par phenotype as shown unambiguously by 4,6-diamidino-2-phenylindole stained nucleoids in parA mutant cells with the W3110 genetic background. Both salt-repairable ts and Par traits were corrected concomitantly by a plasmid carrying the chromosomal region solely for the gyrB gene. This strongly suggests that parA is an allele of gyrB. 相似文献
79.
80.
Kazuhiro Hirakura Makoto Morita Kaoru Nakajima Yukinobu Ikeya Hiroshi Mitsuhashi 《Phytochemistry》1991,30(12):4053-4055
Three new acetylated polyacetylenes named ginsenoynes F, G and H were isolated from the hexane extract of the roots of Panax ginseng. The structures were determinated by spectral and chemical methods. 相似文献