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61.
Genomic fingerprints of C. michiganensis subsp. sepedonicus were generated by CHEF gel electrophoresis of restriction digested high-molecular weight DNA. Low levels of intra-subspecific
variation were detected by cluster analysis of the fingerprints. Four haplotypes were identified by genomic fingerprinting
with HindIII, and eight were identified with EcoRI. Haplotypes generated with HindIII were less similar than those generated by EcoRI. Haplotypes generated with HindIII formed groups that corresponded well with plant reactions of the strains, but similar types of groupings were less apparent
with haplotypes generated with EcoRI. When disease severity in eggplant and potato, population size in potato, and ability to induce a hypersensitive response
(HR) in tobacco were overlaid onto dendograms of genetic similarity, avirulent HR-negative strains clustered separately from
virulent HR-positive strains in both EcoRI and HindIII profiles. Avirulent HR-positive strains that lack pCS1 clustered with avirulent HR-negative strains in a EcoRI dendogram, but clustered with virulent HR-positive strains in a HindIII dendogram. Genomic fingerprinting of high-molecular weight DNA fragments provided a means for detecting genomic variability
associated with virulence in C. michiganensis subsp. sepedonicus.
Received: 1 March 2001 / Accepted: 7 June 2001 相似文献
62.
A J Ross S P Amy P L Mahar T Lindsten C M Knudson C B Thompson S J Korsmeyer G R MacGregor 《Developmental biology》2001,239(2):295-308
Male mice deficient in BCLW, a death-protecting member of the BCL2 family, are sterile due to an arrest in spermatogenesis that is associated with a gradual loss of germ cells and Sertoli cells from the testis. As Bclw is expressed in both Sertoli cells and diploid male germ cells, it has been unclear which of these cell types requires BCLW in a cell-autonomous manner for survival. To determine whether death of Sertoli cells in Bclw mutants is influenced by the protracted loss of germ cells, we examined testes from Bclw/c-kit double mutant mice, which lack germ cells from birth. Loss of BCLW-deficient Sertoli cells occurs in the absence of germ cells, indicating that germ cell death is not required to mediate loss of Sertoli cells in BCLW-deficient mice. This suggests that Sertoli cells require BCLW in a cell-intrinsic manner for long-term survival. The loss of Sertoli cells in Bclw mutants commences shortly after Sertoli cells have become postmitotic. In situ hybridization analysis indicates that Bclw is expressed in Sertoli cells both before and after exit from mitosis. Therefore, Bclw-independent pathways promote the survival of undifferentiated, mitotic Sertoli cells. We show that BAX and BAK, two closely related death-promoting members of the BCL2 family, are expressed in Sertoli cells. To determine whether either BAX or BAK activity is required for Sertoli cell death in Bclw mutant animals, we analyzed survival of Sertoli cells in Bclw/Bax and Bclw/Bak double homozygous mutant mice. While mutation of Bak had no effect, ablation of Bax suppressed the loss of Sertoli cells in Bclw mutants. Thus, BCLW mediates survival of postmitotic Sertoli cells in the mouse by suppressing death-promoting activity of BAX. 相似文献
63.
HIV-particles in spermatozoa of patients with AIDS and their transfer into the oocyte 总被引:11,自引:1,他引:10
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B Baccetti A Benedetto AG Burrini G Collodel EC Ceccarini N Crisa A Di Caro M Estenoz AR Garbuglia A Massacesi P Piomboni T Renieri D Solazzo 《The Journal of cell biology》1994,127(4):903-914
By immunocytochemistry and in situ hybridization at the electron microscopy level, and by the PCR technique, we have shown that HIV-1 binds and enters normal sperm; that viral particles, their antigens, and nucleic acid are present in sperm from HIV-1 infected men; and that such sperm can transfer HIV-1 like particles to normal human oocytes. We also present evidence that a galactosylceramide-like compound is present on the sperm membrane and could function as an alternative receptor for HIV. 相似文献
64.
Prospects for estimating nucleotide divergence with RAPDs 总被引:11,自引:0,他引:11
The technique of random amplification of polymorphic DNA (RAPD), which is
simply polymerase chain reaction (PCR) amplification of genomic DNA by a
single short oligonucleotide primer, produces complex patterns of anonymous
polymorphic DNA fragments. The information provided by these banding
patterns has proved to be of great utility for mapping and for verification
of identity of bacterial strains. Here we consider whether the degree of
similarity of the banding patterns can be used to estimate nucleotide
diversity and nucleotide divergence. With haploid data, fragments generated
by RAPD-PCR can be treated in a fashion very similar to that for
restriction-fragment data. Amplification of diploid samples, on the other
hand, requires consideration of the fact that presence of a band is
dominant to absence of the band. After describing a method for estimating
nucleotide divergence on the basis of diploid samples, we summarize the
restrictions and criteria that must be met when RAPD data are used for
estimating population genetic parameters.
相似文献
65.
Severson DW Knudson DL Soares MB Loftus BJ 《Insect biochemistry and molecular biology》2004,34(7):715-721
The mosquito, Aedes aegypti, is the primary, worldwide arthropod vector for the yellow fever and dengue viruses. As it is also one of the most tractable mosquito species for laboratory studies, it has been and remains one of the most intensively studied arthropod species. This has resulted in the development of detailed genetic and physical maps for Ae. aegypti and considerable insight into its genome organization. The research community is well-advanced in developing important molecular tools that will facilitate a whole genome sequencing effort. This includes generation of BAC clone end sequences, physical mapping of selected BAC clones and generation of EST sequences. Whole genome sequence information for Ae. aegypti will provide important insight into mosquito chromosome evolution and allow for the identification of genes and gene function. These functions may be common to all mosquitoes or perhaps unique to individual species, possibly specific to host-seeking and blood-feeding behaviors, as well as the innate immune response to pathogens encountered during blood-feeding. This information will be invaluable to the global effort to develop novel strategies for preventing arthropod-borne disease transmission. 相似文献
66.
Stretching has no effect on tennis serve performance 总被引:1,自引:0,他引:1
Knudson DV Noffal GJ Bahamonde RE Bauer JA Blackwell JR 《Journal of strength and conditioning research / National Strength & Conditioning Association》2004,18(3):654-656
Stretching prior to vigorous physical activity has been shown to decrease high-force muscular performance, but little is known about the effect of stretching on speed and accuracy movements. Serving percentage and radar measurements of ball speed were studied to examine the acute effect of stretching on tennis serve performance. Eighty-three tennis players from beginning level to advanced volunteered to serve following traditional (T) warm-up and traditional plus stretching (S) conditions. Service speeds and service percentage of each condition were measured. Dependent t-tests showed nonsignificant effects of stretching on service speed (p = 0.06) or accuracy (p = 0.35), and this lack of an effect was similar for all skill levels, age, and gender. The large sample and good statistical power in this study indicated that these observations are not likely type II errors. There was no short-term effect of stretching in the warm-up on the tennis serve performance of adult players, so adding stretching to the traditional 5-minute warm-up in tennis does not affect serve performance. 相似文献
67.
Bentzel DE Elliott TB Keller CE Brook I Shoemaker MO Knudson GB 《Comparative medicine》2004,54(2):185-192
Klebsiella pneumoniae is a common cause of nosocomially acquired pneumonia in immunocompromised patients. Previously, we established a pneumonia model using Klebsiella pneumoniae in B6D2F1/J mice sublethally irradiated with 7-Gy 60Co gamma-radiation and inoculated intratracheally. In the study reported here, we investigated survival of mice following 10 days of antimicrobial therapy with ceftriaxone, gentamicin, gatifloxacin, and a ceftriaxone-gentamicin combination given once daily. Survival was significantly prolonged in response to all therapies. However, survival of mice was 95% when treated with the ceftriaxone-gentamicin combination followed by ceftriaxone alone (75%), and gatifloxacin (80%), whereas survival for controls was 0%. In addition, resistance to any of the treatments did not develop during the study. We conclude that an immunocompromised status does not alter the Infectious Disease Society of America's primary recommendation for treating community-acquired K. pneumoniae pneumonia using a third-generation cephalosporin, with or without an aminoglycoside. 相似文献
68.
69.
Ben T. Danielson Cheryl B. Knudson Warren Knudson 《The Journal of biological chemistry》2015,290(15):9555-9570
In many cells hyaluronan receptor CD44 mediates the endocytosis of hyaluronan and its delivery to endosomes/lysosomes. The regulation of this process remains largely unknown. In most extracellular matrices hyaluronan is not present as a free polysaccharide but often is found in complex with other small proteins and macromolecules such as proteoglycans. This is especially true in cartilage, where hyaluronan assembles into an aggregate structure with the large proteoglycan termed aggrecan. In this study when purified aggrecan was added to FITC-conjugated hyaluronan, no internalization of hyaluronan was detected. This suggested that the overall size of the aggregate prevented hyaluronan endocytosis and furthermore that proteolysis of the aggrecan was a required prerequisite for local, cell-based turnover of hyaluronan. To test this hypothesis, limited C-terminal digestion of aggrecan was performed to determine whether a size range of aggrecan exists that permits hyaluronan endocytosis. Our data demonstrate that only limited degradation of the aggrecan monomer was required to allow for hyaluronan internalization. When hyaluronan was combined with partially degraded, dansyl chloride-labeled aggrecan, blue fluorescent aggrecan was also visualized within intracellular vesicles. It was also determined that sonicated hyaluronan of smaller molecular size was internalized more readily than high molecular mass hyaluronan. However, the addition of intact aggrecan to hyaluronan chains sonicated for 5 and 10 s reblocked their endocytosis, whereas aggregates containing 15-s sonicated hyaluronan were internalized. These data suggest that hyaluronan endocytosis is regulated in large part by the extracellular proteolytic processing of hyaluronan-bound proteoglycan. 相似文献
70.
Frederique M Moret Cornelis E Hack Kim MG van der Wurff-Jacobs Wilco de Jager Timothy RDJ Radstake Floris PJG Lafeber Joel AG van Roon 《Arthritis research & therapy》2013,15(5):R155