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61.
62.
J. W. Breneman P. M. Yau R. R. Swiger R. Teplitz H. A. Smith J. D. Tucker E. M. Bradbury 《Chromosoma》1996,105(1):41-49
The expression of genes in mammalian cells depends on many factors including position in the cell cycle, stage of differentiation,
age, and environmental influences. As different groups of genes are expressed, their packaging within chromatin changes and
may be detected at the chromsomal level. The organization of DNA within a chromosome is determined to a large extent by the
positively charged, highly conserved histones. Histone subtypes and the reversible chemical modifications of histones have
been associated with gene activity. Active or potentially active genes have been associated with hyperacetylated histones
and inactive genes with nonacetylated histones. Sodium butyrate increases the acetylation levels of histones in cell cultures
and acts as both an inducer of gene activity and as a cell-cycle block. We describe a method to label the interphase distribution
of DNA associated with various histone acetylation stages on chromosomes. Nucleosomes from untreated and butyrate-treated
HeLa cells were fractionated by their acetylation level and the associated DNA labeled, and hybridized to normal human chromosomes.
In the sodium butyrate-treated cells the resulting banding patterns of the high- and low-acetylated fractions were strikingly
different. DNA from low-acetylated chromatin labeled several pericentric regions, whereas hybridization with DNA from highly
acetylated chromatin resulted in a pattern similar to inverse G-bands on many chromsomes. The results from noninduced cells
at both high and low acetylation levels were noticeably different from their induced counterparts. The capture and hybridization
of DNA from interphase chromatin at different acetylation states provides a “snap-shot” of the distribution of gene activity
on chromosomes at the time of cell harvest.
Edited by: P.B. Moens 相似文献
63.
64.
I. G. Priede L. M. Williams H.-J. Wagner A. Thom I. Brierley M. A. Collins S. P. Collin N. R. Merrett C. Yau 《Proceedings. Biological sciences / The Royal Society》1999,266(1435):2295
Relative eye size, gross brain morphology and central localization of 2-[125I]iodomelatonin binding sites and melatonin receptor gene expression were compared in six gadiform fish living at different depths in the north-east Atlantic Ocean: Phycis blennoides (capture depth range 265 to 1260 m), Nezumia aequalis (445 to 1512 m), Coryphaenoides rupestris (706 to 1932 m), Trachyrincus murrayi (1010 to 1884 m), Coryphaenoides guentheri (1030 m) and Coryphaenoides (Nematonurus) armatus (2172 to 4787 m). Amongst these, the eye size range was 0.15 to 0.35 of head length with a value of 0.19 for C. (N.) armatus, the deepest species. Brain morphology reflected behavioural differences with well-developed olfactory regions in P. blennoides, T. murrayi and C. (N.) armatus and evidence of olfactory deficit in N. aequalis, C. rupestris and C. guentheri. All species had a clearly defined optic tectum with 2-[125I]iodomelatonin binding and melatonin receptor gene expression localized to specific brain regions in a similar pattern to that found in shallow-water fish. Melatonin receptors were found throughout the visual structures of the brains of all species. Despite living beyond the depth of penetration of solar light these fish have retained central features associated with the coupling of cycles of growth, behaviour and reproduction to the diel light–dark cycle. How this functions in the deep sea remains enigmatic. 相似文献
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66.
67.
Tan To Cheung Ronnie T. P. Poon Kenneth S. H. Chok Albert C. Y. Chan Simon H. Y. Tsang Wing Chiu Dai Thomas C. C. Yau See Ching Chan Sheung Tat Fan Chung Mau Lo 《PloS one》2014,9(4)
Background and aim
Spontaneous rupture of hepatocellular carcinoma (HCC) carries a high mortality. The use of radiofrequency ablation (RFA) in recent years has enriched the armamentarium for hemostasis of spontaneously ruptured HCCs but its results have not been documented. This study investigated the prognosis and outcome of spontaneous rupture of HCC as well as the results of using RFA for hemostasis.Patients and method
From January 1991 to December 2010, 5283 patients were diagnosed with HCC at our hospital, and 189 of them had spontaneous rupture of HCCs. They were grouped under two periods: period 1, 1991–2000, n = 70; period 2, 2001–2010, n = 119. RFA was available in period 2 only.Results
Hepatitis B virus infection was predominant in both periods. Surgical hemostasis was mainly achieved by hepatic artery ligation in period 1 and by RFA in period 2. The 30-day hospital mortality after surgical treatment was 55.6% (n = 18) in period 1 and 19.2% (n = 26) in period 2 (p = 0.012). Multivariate analysis identified 4 independent factors for better overall survival, namely, hemostasis by transarterial chemoembolization (hazard ratio 0.516, 95% confidence interval 0.354–0.751), hemostasis by RFA (hazard ratio 0.431, 95% confidence interval 0.236–0.790), having surgery as a subsequent treatment (hazard ratio 0.305, 95% confidence interval 0.186–0.498), and a serum total bilirubin level <19 umol/L (hazard ratio 1.596, 95% confidence interval 1.137–2.241).Conclusion
The use of RFA for hemostasis during laparotomy greatly reduced the hospital mortality rate when compared with conventional hepatic artery ligation. 相似文献68.
Zalensky AO Siino JS Gineitis AA Zalenskaya IA Tomilin NV Yau P Bradbury EM 《The Journal of biological chemistry》2002,277(45):43474-43480
Human sperm, unlike the sperm of other mammals, contain replacement histones with unknown biological functions. Here, we report the identification of the novel human gene coding for a testis/sperm-specific histone H2B (hTSH2B). This variant histone is 85% homologous to somatic H2B and has over 93% homology with the testis H2B of rodents. Using genomic PCR, two genetic alleles of hTSH2B were found in the human population. The hTSH2B gene is transcribed exclusively in testis, and the corresponding protein is also present in mature sperm. We expressed recombinant hTSH2B and identified this protein with a particular H2B subtype expressed in vivo. The subnuclear distribution of H2B variants in sperm was determined using biochemical fractionation and immunoblotting. The H2B variant associated with telomere-binding activity () was solubilized by Triton X-100 or micrococcal nuclease extraction, whereas hTSH2B was relatively tightly bound in nuclei. Immunofluorescence showed that hTSH2B was concentrated in spots located at the basal nuclear area of a subpopulation (20% of cells) of mature sperm. This fact may be of particular importance, because the hTSH2B "positive" and "negative" sperm cells may undergo significantly different decondensation processes following fertilization. 相似文献
69.
T Ziegelhoffer P Yau G N Chandrasekhar J Kochan C Georgopoulos H Murialdo 《The Journal of biological chemistry》1992,267(1):455-461
The Nu3 gene of bacteriophage lambda resides within a cluster of genes that specify structural components of the bacteriophage head. Previous experiments indicate that the Nu3 gene product (gpNu3) is associated with immature proheads but is not detectable in mature proheads or bacteriophage particles, hence its classification as a scaffolding protein. The Nu3 gene has been cloned and overexpressed, and its protein product has been purified. The purified protein is biologically active, as demonstrated by its ability to complement a gpNu3-deficient extract in an in vitro assembly reaction. The sequence of the amino terminus of the protein indicates that translation of Nu3 starts at nucleotide position 5,342 on the standard lambda DNA sequence, yielding a protein with a calculated Mr of 13,396. A combination of gel exclusion chromatography and velocity sedimentation gradient data indicates that gpNu3 possesses an unusually elongated shape. 相似文献
70.
Northeast Red Beans Produce a Thermostable and pH-Stable Defensin-Like Peptide with Potent Antifungal Activity 总被引:1,自引:0,他引:1
A 5.4-kDa antifungal peptide was purified from Phaseolus vulgaris L. cv. “northeast red bean” using a protocol that entailed affinity chromatography, ion exchange chromatography, and gel filtration. The molecular mass was determined by matrix-assisted laser desorption ionization time-of-flight. The N-terminal amino acid sequence of the peptide was highly homologous to defensins and defensin-like peptides from several plant species. The peptide impeded the growth of a number of pathogenic fungi, including Mycosphaerella arachidicola Khokhr. (IC50 = 1.7 μM), Setosphaeria turcica Luttr., Fusarium oxysporum Schltdl., and Valsa mali Miyabe & G. Yamada. Antifungal activity of the peptide was fully preserved at temperatures up to 100 °C and pH values from 0 to 12. Congo red deposition at the hyphal tip of M. arachidicola was detected after exposure to the peptide, signifying that the peptide had suppressed hyphal growth. The antifungal peptide did not manifest antiproliferative activity toward human breast cancer MCF7 cells and hepatoma HepG2 cells, in contradiction to the bulk of previously reported plant defensins. The data suggest distinct structural requirements for antifungal and antiproliferative activities. 相似文献