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71.
Although cellular damage during cryopreservation of freshwater fish spermatozoa has been reported in several studies, there is a lack of correlation between this damage and the fertility rates of eggs using postthawed milt. The apparent lack of such correlation may be due to other undetected sublethal cryodamage, which could affect the cell functionality and viability. This may be extremely important for freshwater fish spermatozoa whose ability to fertilize the egg requires dilution in water or hypoosmotic solutions, an hazardous environment for the cells. This study tested the change in cell permeability during cryopreservation, using Hoechst 33258 to assess cell permeability. The permeability of spermatozoa at different times after dilution in several hypoosmotic media were investigated. In the first trial, fresh semen, sperm diluted in freezing media (CPT), and freeze/thawed semen were studied. Three CPT were tested (Me2SO, DMA, and methanol). In the second trial, the addition of egg yolk as a membrane stabilizer was investigated. Samples were frozen at -20 degreesC/min in a programmable cooler and thawed in a 25 degreesC water bath. Dilution in the CPTs slightly increased the susceptibility of cells to damage but freezing/thawing caused a dramatic increase in the fragility of cells, which were killed in a few seconds after their contact with the hypoosmotic solutions. Egg yolk provided a significant protection to the membrane, allowing the cells a greater and more prolonged survival in the fertilization media. Samples frozen with Me2SO displayed the best results. These results are consistent with the achieved fertility rates that demonstrated sublethal cryodamage in the function of the sperm membrane that was not detected by standard procedures. Copyright 1998 Academic Press. 相似文献
72.
An exception to the generally conservative nature of plastid gene evolution
is the gene coding for the beta" subunit of RNA polymerase, rpoC2. Previous
work by others has shown that maize and rice have an insertion in the
coding region of rpoC2, relative to spinach and tobacco. To assess the
distribution of this extra coding sequence, we surveyed a broad
phylogenetic sample comprising 55 species from 17 angiosperm families by
using Southern hybridization. The extra coding sequence is restricted to
the grasses (Poaceae). DNA sequence analysis of 11 species from all five
subfamilies within the grass family demonstrates that the extra sequence in
the coding region of rpoC2 is a repetitive array that exhibits more than a
twofold increase in nucleotide substitution, as well as a large number of
insertion/deletion events, relative to the adjacent flanking sequences. The
structure of the array suggests that slipped-strand mispairing causes the
repeated motifs and adds to the mechanisms through which the coding
sequence of plastid genes are known to evolve. Phylogenetic analyses based
on the sequence data from grass species support several relationships
previously suggested by morphological work, but they are ambiguous about
broad relationships within the family.
相似文献
73.
Nucleolar organizer regions are nucleolar components that contain proteins that are stained selectively by silver methods; they can be identified as black dots throughout the nucleolus and are known as silver binding nucleolar organizer regions (AgNOR). The number of AgNOR is related to the cell cycle and the proliferative activity of the cells. We investigated AgNOR using exfoliative cytology smears of potentially malignant oral lesions. Eighty individuals were divided into four equal groups: healthy controls, oral leukoplakia, oral submucous fibrosis and oral squamous cell carcinoma. The mean number of AgNOR in each study group gradually increased from control to oral leukoplakia to oral submucous fibrosis to oral squamous cell carcinoma. The proliferative index was increased in the oral premalignant and malignant patients compared to normal subjects. The mean AgNOR size gradually increased from control to oral leukoplakia to oral submucous fibrosis to oral squamous cell carcinoma. Spherical shaped AgNOR were most common in controls, whereas large, clustered and kidney shapes were most common in oral squamous cell carcinoma. Multiparameter analysis of AgNOR in oral exfoliative smears is a simple, sensitive and cost-effective method for differentiating premalignant from malignant lesions and can be used in conjunction with routine cytomorphological evaluation. 相似文献
74.
Champica K. Bodinayake Ajith DeS Nagahawatte Vasantha Devasiri Niroshana J. Dahanayake Gaya B. Wijayaratne Nayani P. Weerasinghe Madureka Premamali Tianchen Sheng Bradley P. Nicholson Harshanie A. Ubeysekera Ruvini MP Kurukulasooriya Aruna D. de Silva Truls
stbye Christopher W. Woods L. Gayani Tillekeratne 《PLoS neglected tropical diseases》2022,16(5)
75.
A non-methylated CpG-rich island associated with the human muscle-specific carbonic anhydrase III gene 总被引:1,自引:0,他引:1
A cluster of CpG dinucleotides immediately upstream from exon 1 in the muscle-specific carbonic anhydrase III gene (CAIII) resembles the 'HpaII tiny fragment' (HTF) islands characteristic of mammalian 'housekeeping' genes. Since this CAIII gene shows tissue-specific expression we have carried out a detailed examination of methylation status within the CpG cluster using a polyacrylamide gel/electroblot procedure to extend the range of conventional Southern blotting. None of the clustered CpGs are methylated in DNA from muscle or other somatic tissues or in DNA from spermatozoa although flanking CpGs are methylated. Comparison with a candidate HTF island from the more ubiquitously expressed carbonic anhydrase II gene (CAII) shows that the CAII CpG cluster is markedly more CpG-rich than that from the strictly tissue-specific CAIII gene. 相似文献
76.
77.
78.
Brain acetylcholinesterase (EC 3. 1. 1. 7) isoenzymes of 15- and 30-day-old rats were found to be inhibited by 2.5 mg/kg and 1.25 mg/kg dosage levels of intraperitoneally administered parathion (E-605; O, O-diethyl-p-nitrophenyl phosphorothionate). With 2.5 mg/kg dose level, the response of isoenzymes in 15- and 30-day-old rats was similar. At both ages, there was no significant sex difference in the degree of depression of the isoenzymes. There were no significant regional differences in the degree of inhibition of acetylcholinesterase isoenzymes in the rat brain. At 1.25 mg/kg dosage level, a differential isoenzyme inhibition was evident, with the major isoenzyme (isoenzyme 3) exhibiting the greatest sensitivity to the inhibitor in all brain areas examined. The course of isoenzyme depression and recovery following the administration of parathion differed in brain, serum and skeletal muscle. Whereas brain isoenzymes exhibited most marked inhibition at 2 h after injection, inhibition of serum and skeletal muscle isoenzymes was more prolonged. At 4 h after injection, these isoenzymes were still inhibited while brain isoenzymes had recovered to a substantial degree. Twenty four h following the injection of parathion, when brain and serum acetylcholinesterase isoenzymes had returned to control activity levels, isoenzymes of skeletal muscle demonstrated only minimal recovery. 相似文献
79.
80.
Enola Proctor Christopher Carpenter C Hendricks Brown Gila Neta Russell Glasgow Jeremy Grimshaw Borsika Rabin Maria Fernandez Ross Brownson Geoff Curran Brian Mittmann Linda Collins Lawrence Palinkas Naihua Duan Andrea Wallace Ken Wells Rachel Tabak Greg Aarons 《Implementation science : IS》2015,10(Z1):A13