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81.
THE FINE STRUCTURE OF THE NUCLEOLUS IN MITOTIC DIVISIONS OF CHINESE HAMSTER CELLS IN VITRO 总被引:7,自引:6,他引:1 下载免费PDF全文
B. R. Brinkley 《The Journal of cell biology》1965,27(2):411-422
The nucleolus of Chinese hamster tissue culture cells (strain Dede) was studied in each stage of mitosis with the electron microscope. Mitotic cells were selectively removed from the cultures with 0.2 per cent trypsin and fixed in either osmium tetroxide or glutaraldehyde followed by osmium tetroxide. The cells were embedded in both prepolymerized methacrylate and Epon 812. Thin sections of interphase nucleoli revealed two consistent components; dense 150-A granules and fine fibrils which measured 50 A or less in diameter. During prophase, distinct zones which were observed in some interphase nucleoli (i.e. nucleolonema and pars amorpha) were lost and the nucleoli were observed to disperse into smaller masses. By late prophase or prometaphase, the nucleoli appeared as loosely wound, predominantly fibrous structures with widely dispersed granules. Such structures persisted throughout mitosis either free in the cytoplasm or associated with the chromosomes. At telophase, those nucleolar bodies associated with the chromosomes became included in the daughter nuclei, resumed their compact granular appearance, and reorganized into an interphase-type structure. 相似文献
82.
For over a century, the terms centromere and kinetochore have been used interchangeably to describe a complex locus on eukaryotic chromosomes that attaches chromosomes to spindle fibres and facilitates chromosome movement in mitosis and meiosis. This region has become the focus of research aimed at defining the mechanism of chromosome segregation. A variety of new molecular probes and vastly improved optical-imaging technology have provided much new information on the structure of this locus and raised new hopes that an understanding of its function may soon be at hand. 相似文献
83.
Peripheral alpha1,3-fucosylation of glycans occurs by the action of either
one of five different alpha1,3-fucosyltransferases (Fuc-Ts) cloned to date.
Fuc-TVI is one of the alpha1,3-fucosyltransferases which is capable to
synthesize selectin ligands. The major alpha1, 3- fucosyltransferase
activity in human plasma is encoded by the gene for fucosyltransferase VI,
which presumably originates from liver cells. While the sequence,
chromosomal localization, and kinetic properties of Fuc-TVI are known,
immunocytochemical localization and trafficking studies have been
impossible because of the lack of specific antibodies. Here we report on
the development and characterization of a peptide-specific polyclonal
antiserum monospecific to Fuc-TVI and an antiserum to purified soluble
recombinant Fuc-TVI crossreactive with Fuc-TIII and Fuc-TV. Both antisera
were applied for immunodetection in stably transfected CHO cells expressing
the full-length form of this enzyme (CHO clone 61/11). Fuc-TVI was found to
be a resident protein of the Golgi apparatus. In addition, more than 30% of
cell-associated and released enzyme activity was found in the medium.
Maturation and release of Fuc-TVI was analyzed in metabolically labeled CHO
61/11 cells followed by immunoprecipitation. Fuc-TVI occurred in two forms
of 47 kDa and 43 kDa bands, while the secreted form was detected as a 43
kDa. These two different intracellular forms arose by posttranslational
modification, as shown by pulse-chase experiments. Fuc-TVI was released to
the supernatant by proteolytic cleavage as a partially endo-H resistant
glycoform.
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84.
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86.
Nishino M Kurasawa Y Evans R Lin SH Brinkley BR Yu-Lee LY 《Current biology : CB》2006,16(14):1414-1421
The equal distribution of chromosomes during mitosis is critical for maintaining the integrity of the genome. Essential to this process are the capture of spindle microtubules by kinetochores and the congression of chromosomes to the metaphase plate . Polo-like kinase 1 (Plk1) is a mitotic kinase that has been implicated in microtubule-kinetochore attachment, tension generation at kinetochores, tension-responsive signal transduction, and chromosome congression . The tension-sensitive substrates of Plk1 at the kinetochore are unknown. Here, we demonstrate that human Nuclear distribution protein C (NudC), a 42 kDa protein initially identified in Aspergillus nidulans and shown to be phosphorylated by Plk1 , plays a significant role in regulating kinetochore function. Plk1-phosphorylated NudC colocalizes with Plk1 at the outer plate of the kinetochore. Depletion of NudC reduced end-on microtubule attachments at kinetochores and resulted in defects in chromosome congression at the metaphase plate. Importantly, NudC-deficient cells exhibited mislocalization of Plk1 and the Kinesin-7 motor CENP-E from prometaphase kinetochores. Ectopic expression of wild-type NudC, but not NudC containing mutations in the Plk1 phosphorylation sites, recovered Plk1 localization at the kinetochore and rescued chromosome congression. Thus, NudC functions as both a substrate and a spatial regulator of Plk1 at the kinetochore to promote chromosome congression. 相似文献
87.
Methicillin-resistant Staphylococcus aureus (MRSA) poses a serious problem in dairy animals suffering from mastitis. In the present study, the distribution of mastitic
MRSA and antibiotic resistance was studied in 107 strains of S. aureus isolated from milk samples from 195 infected udders. The characterizations pathogenic factors (adhesin and toxin genes) and
antibiotic susceptibility of isolates were carried out using gene amplification and disc diffusion assays, respectively. A
high prevalence of MRSA was observed in the tested isolates (13.1%). The isolates were also highly resistant to antibiotics,
i.e. 36.4% were resistant to streptomycin, 33.6% to oxytetracycline, 29.9% to gentamicin and 26.2% each to chloramphenicol,
pristinomycin and ciprofloxacin. A significant variation in the expression of pathogenic factors (Ig, coa and clf) was observed in these isolates. The overall distribution of adhesin genes ebp, fib, bbp, fnbB, cap5, cap8, map and cna in the isolates was found to be 69.1, 67.2, 6.5, 20.5, 60.7, 26.1, 81.3 and 8.4%, respectively. The presence of fib, fnbB, bbp and map genes was considerably greater in MRSA than in methicillin-susceptible S. aureus (MSSA) isolates. The proportions of toxin genes, namely, hlb, seb, sec, sed, seg and sei, in the isolates were found to be 94.3, 0.9, 8.4, 0.9, 10.2 and 49.5%, respectively. The proportions of agr genes I, II, III and IV were found to be 39.2, 27.1, 21.5 and 12.1%, respectively. A few isolates showed similar antibiotic-resistance
patterns, which could be due to identical strains or the dissemination of the same strains among animals. These findings can
be utilized in mastitis treatment programmes and antimicrobials strategies in organized herds. 相似文献
88.
ABSTRACT Distress calls are signals effective over a long distance. They are well known to evoke interspecific reactions. We suggest that the interspecificity phenomenon results from the use of similar laws of decoding by the species concerned. These laws must take into account the transmission channel which always has a great influence on long-range communication. We tested our hypothesis by broadcasting simplified synthetic calls to two species of birds: the herring gull and the starling. The various calls differed in terms of frequency modulation (FM). Two main conclusions emerged from this series of tests: 1. The parameters used for recognition are not sophisticated: a simple slope applied to a carrier frequency that corresponds to the acoustic shape of a distress call is sufficient to confer a distress meaning to the signal. The basic rules are the same for the gull and the starling, with differences only in the acceptance level of the species. 2. The system of recognition is based upon parameters not altered by the environment: the birds make use of the slow frequency modulations (FMI). In contrast, the fast frequency sweeps (FMII) which are modified during propagation do not seem to be utilised. The use of these characteristics of distress calls for recognition allows interspecificity and maximum efficiency for propagation over long distances.
RESUME
Une particularité des cris de détresse est leur action interspécifique. Nous suggérons que cette interspécificité résulte de l'emploi d'une loi de décodage qui est commune à plusieures espèces. Cette loi doit tenir compte des propriétés du canal car ce dernier a toujours une grande influence sur les signaux de longue portée acoustique, tels que les cris de détresse. Pour tester cette hypothèse, nous avons fait appel à deux espèces: le Goéland argenté (Larus argentatus) et l'Etourneau (Sturnus vulgaris). Les signaux que nous avons diffusés étaient obtenus par synthèse. Ils étaient plus simples que les signaux naturels et différaient par la modulation de fréquence (FM). Deux résultats principaux émergent de ces séries d'expériences: 1. Le procédé de décodage n'est pas sophistiqué: une simple pente appliquée à la porteuse est nécessaire et il suffit de mimer, meme approximativement, la pente rencontrée dans les signaux naturels, Cette règle fondamentale est commune au Goéland et à l'Etourneau. Les petites différences que l'on peut néanmoins observer sont relatives aux seuils de décodage. 2. Le décodage repose sur des paramètres qui ne sont pas altérés par le canal: l'oiseau utilise la modulation lente de fréquence. Par contre les excursions rapides de fréquence semblent n'étre d'aucune utilité lors du décodage. En conclusion, l'universalité des paramètres impliqués et de la loi de décodage est responsable de l'interspécificité des signaux de détresse. Les simplifications liées à cette universalité résultent des contraintes imposées par le canal. 相似文献
89.
Hochheiser H Aronow BJ Artinger K Beaty TH Brinkley JF Chai Y Clouthier D Cunningham ML Dixon M Donahue LR Fraser SE Hallgrimsson B Iwata J Klein O Marazita ML Murray JC Murray S de Villena FP Postlethwait J Potter S Shapiro L Spritz R Visel A Weinberg SM Trainor PA 《Developmental biology》2011,(2):175-182
The FaceBase Consortium consists of ten interlinked research and technology projects whose goal is to generate craniofacial research data and technology for use by the research community through a central data management and integrated bioinformatics hub. Funded by the National Institute of Dental and Craniofacial Research (NIDCR) and currently focused on studying the development of the middle region of the face, the Consortium will produce comprehensive datasets of global gene expression patterns, regulatory elements and sequencing; will generate anatomical and molecular atlases; will provide human normative facial data and other phenotypes; conduct follow up studies of a completed genome-wide association study; generate independent data on the genetics of craniofacial development, build repositories of animal models and of human samples and data for community access and analysis; and will develop software tools and animal models for analyzing and functionally testing and integrating these data. The FaceBase website (http://www.facebase.org) will serve as a web home for these efforts, providing interactive tools for exploring these datasets, together with discussion forums and other services to support and foster collaboration within the craniofacial research community. 相似文献
90.
Brinkley TE Halverstadt A Phares DA Ferrell RE Prigeon RL Hagberg JM Goldberg AP 《Journal of applied physiology (Bethesda, Md. : 1985)》2011,111(6):1871-1876
Our objective was to test the hypothesis that a common polymorphism in the hepatic lipase (HL) gene (LIPC -514C>T, rs1800588) influences aerobic exercise training-induced changes in TG, very-low-density lipoprotein (VLDL), and high-density lipoprotein (HDL) through genotype-specific increases in lipoprotein lipase (LPL) activity and that sex may affect these responses. Seventy-six sedentary overweight to obese men and women aged 50-75 yr at risk for coronary heart disease (CHD) underwent a 24-wk prospective study of the LIPC -514 genotype-specific effects of exercise training on lipoproteins measured enzymatically and by nuclear magnetic resonance, postheparin LPL and HL activities, body composition by dual energy x-ray absorptiometry and computer tomography scan, and aerobic capacity. CT genotype subjects had higher baseline total cholesterol, HDL-C, HDL(2)-C, large HDL, HDL particle size, and large LDL than CC homozygotes. Exercise training elicited genotype-specific decreases in VLDL-TG (-22 vs. +7%; P < 0.05; CC vs. CT, respectively), total VLDL and medium VLDL, and increases in HDL-C (7 vs. 4%; P < 0.03) and HDL(3)-C with significant genotype×sex interactions for the changes in HDL-C and HDL(3)-C (P values = 0.01-0.02). There were also genotype-specific changes in LPL (+23 vs. -6%; P < 0.05) and HL (+7 vs. -24%; P < 0.01) activities, with LPL increasing only in CC subjects (P < 0.006) and HL decreasing only in CT subjects (P < 0.007). Reductions in TG, VLDL-TG, large VLDL, and medium VLDL and increases in HDL(3)-C and small HDL particles correlated significantly with changes in LPL, but not HL, activity only in CC subjects. This suggests that the LIPC -514C>T variant significantly affects training-induced anti-atherogenic changes in VLDL-TG, VLDL particles, and HDL through an association with increased LPL activity in CC subjects, which could guide therapeutic strategies to reduce CHD risk. 相似文献