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71.
Restriction-map variation associated with the G6PD polymorphism in natural populations of Drosophila melanogaster 总被引:10,自引:0,他引:10
Restriction-map variation was studied in 126 copies of the G6pd region in X
chromosome lines of Drosophila melanogaster from North America, Europe, and
Africa. Special attention was focused on the distribution of variation
relative to the geographically variable polymorphism for two
electrophoretic variants. Nucleotide heterozygosity as determined by eight
six-cutter restriction enzymes for the 13-kb region is estimated, on the
basis of the worldwide sample, to be 0.065%, which is the lowest value
reported for any comparable region in the D. melanogaster genome.
Significant linkage disequilibrium between electrophoretic alleles and
restriction-site variation is observed for several sites. In contrast to
published studies of other genetic regions, there are large insertions that
reach significant frequencies and are found across considerable geographic
distances. There is a clustering of this variation inside the first large
intervening sequence of the G6PD gene.
相似文献
72.
M Marcelli W D Tilley C M Wilson J E Griffin J D Wilson M J McPhaul 《Molecular endocrinology (Baltimore, Md.)》1990,4(8):1105-1116
We have isolated and characterized the gene encoding the human androgen receptor. The coding sequence is divided into eight coding exons and spans a minimum of 54 kilobases. The positions of the exon boundaries are highly conserved when compared to the location of the exon boundaries of the chicken progesterone and human estrogen receptor genes. Definition of the intron/exon boundaries has permitted the synthesis of specific oligonucleotides for use in the amplification of segments of the androgen receptor gene from samples of total genomic DNA. This technique allows the analysis of all segments of the androgen receptor gene except a small region of exon 1 that encodes the glycine homopolymeric segment. Using these methods we have analyzed samples of DNA prepared from a patient with complete androgen resistance and have detected a single nucleotide substitution at nucleotide 1924 in exon 3 of the androgen receptor gene that results in the conversion of a lysine codon into a premature termination codon at amino acid position 588. The introduction of a termination codon into the sequence of the normal androgen receptor cDNA at this position leads to a decrease in the amount of mRNA encoding the human androgen receptor and the synthesis of a truncated receptor protein that is unable to bind ligand and is unable to activate the long terminal repeat of the mouse mammary tumor virus in cotransfection assays. 相似文献
73.
74.
Leann Tilley Gerard B. Nash Graham L. Jones William H. Sawyer 《The Journal of membrane biology》1991,121(1):59-66
Summary Melanesian ovalocytes from Papua New Guinea have an N-terminal extension of the band 3 polypeptide (Jones, G.L., Edmunson. H.M., Wesche, D., Saul, A. 1990.Biochim. Biophys. Acta
1096:33–40). The ovalocytes showed a threefold increase in shear elastic modulus as determined by micropipette aspiration measurements of membrane rigidity. Time-resolved phosphorescence anisotropy has been used to study the rotational freedom of band 3 in membranes prepared from ovalocytes. The ovalocytic polymorphism was found to be associated with a marked decrease in the rotational mobility of band 3. This may indicate participation of band 3 in large homoaggregates or in complexes with other proteins at the cytoplasmic surface. There was no morphological clustering of band 3 detectable by immunofluorescence microscopy. 相似文献
75.
Paul J. McMillan Mauro Maiorca Eric Hanssen Shannon Kenny Rebecca A. Muhle Martin Melcher David A. Fidock Joseph D. Smith Matthew W. A. Dixon Leann Tilley 《Cellular microbiology》2013,15(8):1401-1418
The human malaria parasite, Plasmodium falciparum, modifies the red blood cells (RBCs) that it infects by exporting proteins to the host cell. One key virulence protein, P. falciparum Erythrocyte Membrane Protein‐1 (PfEMP1), is trafficked to the surface of the infected RBC, where it mediates adhesion to the vascular endothelium. We have investigated the organization and development of the exomembrane system that is used for PfEMP1 trafficking. Maurer's cleft cisternae are formed early after invasion and proteins are delivered to these (initially mobile) structures in a temporally staggered and spatially segregated manner. Membrane‐Associated Histidine‐Rich Protein‐2(MAHRP2)‐containing tether‐like structures are generated as early as 4 h post invasion and become attached to Maurer's clefts. The tether/Maurer's cleft complex docks onto the RBC membrane at ~ 20 h post invasion via a process that is not affected by cytochalasin D treatment. We have examined the trafficking of a GFP chimera of PfEMP1 expressed in transfected parasites. PfEMP1B‐GFP accumulates near the parasite surface, within membranous structures exhibiting a defined ultrastructure, before being transferred to pre‐formed mobile Maurer's clefts. Endogenous PfEMP1 and PfEMP1B‐GFP are associated with Electron‐Dense Vesicles that may be responsible for trafficking PfEMP1 from the Maurer's clefts to the RBC membrane. 相似文献
76.
77.
78.
Identification of sporozoite surface proteins and antigens of Eimeria nieschulzi (Apicomplexa) 总被引:1,自引:0,他引:1
Sodium dodecyl sulfate polyacrylamide gel electrophoresis, immunoblotting, lectin binding, and 125I surface labeling of sporozoites were used to probe sporozoites of the rat coccidian, Eimeria nieschulzi. Analysis of silver stained gels revealed greater than 50 bands. Surface iodination revealed about 14 well labeled, and about 10 weakly labeled but potential, surface proteins. The most heavily labeled surface proteins had molecular masses of 60, 53-54, 45, 28, 23-24, 17, 15, 14, 13, and 12 kD. Following electrophoresis and Western blotting, 2 of the 12 125I labeled lectin probes bound to two bands on the blots, which collectively indicated that two bands were glycosylated. Concanavalin A (ConA) specifically recognized a band at 53 kD, which may represent a surface glycoprotein, and a lectin derived from Osage orange (MPA) bound to a single band at 82-88 kD, that may also be a surface molecule. Immunoblotting using sera collected from rats inoculated orally with oocysts, as well as sera from mice hyperimmunized with sporozoites, revealed that many surface molecules appear to be immunogenic. 相似文献
79.
Aldair JW Pinto Maria M Figueiredo Fabiana L Silva Trycia Martins Marilene SM Michalick Washington L Tafuri Wagner L Tafuri 《Acta veterinaria Scandinavica》2011,53(1):1-8
Background
A nationwide survey on the microbial etiology of cases of subclinical mastitis in dairy cows was carried out on dairy farms in Sweden. The aim was to investigate the microbial panorama and the occurrence of antimicrobial resistance. Moreover, differences between newly infected cows and chronically infected cows were investigated.Methods
In total, 583 quarter milk samples were collected from 583 dairy cows at 226 dairy farms from February 2008 to February 2009. The quarter milk samples were bacteriological investigated and scored using the California Mastitis Test. Staphylococci were tested for betalactamase production and presence of resistance was evaluated in all specific udder pathogens. Differences between newly infected cows and chronically infected cows were statistically investigated using logistic regression analysis.Results
The most common isolates of 590 bacteriological diagnoses were Staphylococcus (S) aureus (19%) and coagulase-negative staphylococci (CNS; 16%) followed by Streptococcus (Str) dysgalactiae (9%), Str. uberis (8%), Escherichia (E.) coli (2.9%), and Streptococcus spp. (1.9%). Samples with no growth or contamination constituted 22% and 18% of the diagnoses, respectively. The distribution of the most commonly isolated bacteria considering only bacteriological positive samples were: S. aureus - 31%, CNS - 27%, Str. dysgalactiae - 15%, Str. uberis - 14%, E. coli - 4.8%, and Streptococcus spp. - 3.1%. There was an increased risk of finding S. aureus, Str. uberis or Str. dysgalactiae in milk samples from chronically infected cows compared to findings in milk samples from newly infected cows. Four percent of the S. aureus isolates and 35% of the CNS isolates were resistant to penicillin G. Overall, resistance to other antimicrobials than penicillin G was uncommon.Conclusions
Staphylococcus aureus and CNS were the most frequently isolated pathogens and resistance to antimicrobials was rare. 相似文献80.
Carmela Ricciardelli David J. Horsfall John M. Skinner Douglas W. Henderson Villis R. Marshall Wayne D. Tilley 《In vitro cellular & developmental biology. Plant》1989,25(11):1016-1024
Summary Primary cultures of smooth muscle cells (SMCs) were obtained by a two-step enzymatic digestion of guinea pig prostatic stroma.
Ultrastructural morphology and growth characteristics of these cells conformed to those reported for SMCs isolated from vascular
and visceral tissue sources. Electron microscopic examination indicated that the cells assumed modified myofibroblastoid features
in culture. Microfilaments with associated dense bodies were markedly depleted in cultured smooth muscle cells, in comparison
with those of the parent tissue. Cultured cells also possessed increased content of rough endoplasmic reticulum indicating
the increased secretory or protein-synthetic capacity of the cells. Immunoperoxidase staining for cytoskeletal markers using
monoclonal antibodies to desmin and vimentin supported the ultrastructural observations, suggesting a decline in desmin-staining
intermediate filaments during “modulation” to the myofibroblastoid form. Despite this depletion of smooth muscle-specific
differentiation markers and reversion to more general mesenchymal properties, the cells retained the ability to contract on
challenge with norepinephrine, and grew in the characteristic “hill and valley” pattern on attaining confluence. Inasmuch
as the estrogen and androgen receptor expression of the parent stromal tissue is also retained, these primary cell cultures
should provide a useful model to study regulation of prostatic development.
This work was supported by research grants from the National Health and Medical Research Council of Australia, the Anti Cancer
Foundation of the Universities of South Australia, and the Flinders Medical Centre Research Foundation. 相似文献