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111.
Molecular chemoprevention by selenium: a genomic approach 总被引:6,自引:0,他引:6
Basic research and clinical chemoprevention trials support the protective role of selenium in cancer prevention but the mechanisms based on the molecular level remain to be fully defined. This mini-review focuses only on the elucidation of the molecular mechanisms of cancer prevention by selenium using the genomics approach; target organs discussed here are breast, prostate, colon and lung. The results described here support the utility of microarray technology in delineating the molecular mechanisms of cancer prevention by selenium. These results are based on studies employing human and rodent cell lines and tissues from animal models ranging from normal to frank cancer. The dose and the form of selenium are determining factors in cancer chemoprevention. The results of the microarray analysis reviewed here indicate that selenium, independent of its form and the target organ examined, alters several genes in a manner that can account for cancer prevention. Selenium can up regulate genes related to phase II detoxification enzymes, certain selenium-binding proteins and select apoptotic genes, while down regulating those related to phase I activating enzymes and cell proliferation. Independent of tissue type, selenium arrests cells in G1 phase of cell cycle, inhibits CYCLIN A, CYCLIN D1, CDC25A, CDK4, PCNA and E2F gene expressions while induces the expressions of P19, P21, P53, GST, SOD, NQO1, GADD153 and certain CASPASES. In addition to those described above, genes such as OPN, which is mainly involved in metastasis and recently reported to be down regulated by selenium, should be considered as potential molecular marker in clinical chemoprevention trials. Collectively, literature data indicate that some of these genes that were altered by selenium are also involved in the development of human cancers described in this review. It appears that androgen receptor status may influence the effect of selenium on gene expression profile in prostate cancer; whether estrogen receptor may influence the effect of selenium on gene expression in breast cancer requires further studies. Knowledge from gene array data in combination with proteomics approaches, using homogenous population of cell types with the aid of laser capture microdissection, may provide an individualized dimension of information on cancer risk and potential targets for its prevention. The molecular (genetic) biomarkers presented in this review will provide the foundation for future studies of the chemopreventive properties of structurally varied selenium compounds. 相似文献
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Sclerotium rolfsii is a destructive soil-borne and postharvest plant pathogen. Use of the antagonistic fungus Trichoderma
sp. has been earlier reported by us to successfully control this pathogen under postharvest conditions. In the present paper
we report on the effects of temperature on the growth and biocontrol potential of Trichoderma sp. on S. rolfsii. Experimental
results indicated that S. rolfsii and Trichoderma sp. have different temperature optima for growth: 30–35 °C for the pathogen
and 25–30 °C for the antagonist. In dual culture, Trichoderma overgrew S. rolfsii at 25 °C and 30 °C, but at 35 °C and 37
°C, S. rolfsii overgrew the colony of Trichoderma. Trichoderma produced higher concentration of fungitoxic metabolites in
broth culture at higher temperatures. In bioassays using ginger slices and whole rhizomes, it has been demonstrated that Trichoderma
is not very effective in suppressing S. rolfsii at temperatures above 30 °C. In light of these results, possible mechanisms
of biocontrol of S. rolfsii as a postharvest pathogen has been discussed. Storage temperature has been suggested as a critical
factor in biocontrol of S. rolfsii.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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116.
Identification of a closely linked DNA marker, DXS178, to further refine the X-linked agammaglobulinemia locus 总被引:12,自引:0,他引:12
S P Kwan J Terwilliger R Parmley G Raghu L A Sandkuyl J Ott H Ochs R Wedgwood F Rosen 《Genomics》1990,6(2):238-242
X-linked agammaglobulinemia (XLA) is an inherited recessive disorder in which the primary defect is not known and the gene product has yet to be identified. Utilizing genetic linkage analysis, we previously localized the XLA gene to the map region of Xq21.3-Xq22 with DNA markers DXS3 and DXS17. In this study, further mapping was performed with two additional DNA probes, DXS94 and DXS178, by means of multipoint analysis of 20 families in which XLA is segregating. Thirteen of these families had been previously analyzed with DXS3 and DXS17. Three crossovers were detected with DXS94 and no recombinations were found between DXS178 and the XLA locus in 9 informative families. Our results show that XLA is closely linked to DXS178 with a two-point lod score of 4.82 and a multipoint lod score of 10.24. Thus, the most likely gene order is DXS3-(XLA,DXS178)-DXS94-DXS17, with the confidence interval for location of XLA lying entirely between DXS3 and DXS94. In 2 of these families, we identified recombinants with DXS17, a locus with which recombination had not previously been detected by others in as many as 40 meiotic events. Furthermore, DXS178 is informative in both of these families and does not show recombination with the disease locus. Therefore, our results indicate that DXS178 is linked tightly to the XLA gene. 相似文献
117.
Guillaume Constantin de Magny Wen Long Christopher W. Brown Raleigh R. Hood Anwar Huq Raghu Murtugudde Rita R. Colwell 《EcoHealth》2009,6(3):378-389
Vibrio cholerae, the causative agent of cholera, is a naturally occurring inhabitant of the Chesapeake Bay and serves as a predictor for
other clinically important vibrios, including Vibrio parahaemolyticus and Vibrio vulnificus. A system was constructed to predict the likelihood of the presence of V. cholerae in surface waters of the Chesapeake Bay, with the goal to provide forecasts of the occurrence of this and related pathogenic
Vibrio spp. Prediction was achieved by driving an available multivariate empirical habitat model estimating the probability of V. cholerae within a range of temperatures and salinities in the Bay, with hydrodynamically generated predictions of ambient temperature
and salinity. The experimental predictions provided both an improved understanding of the in situ variability of V. cholerae, including identification of potential hotspots of occurrence, and usefulness as an early warning system. With further development
of the system, prediction of the probability of the occurrence of related pathogenic vibrios in the Chesapeake Bay, notably
V. parahaemolyticus and V. vulnificus, will be possible, as well as its transport to any geographical location where sufficient relevant data are available. 相似文献
118.
Shechter D Nicklay JJ Chitta RK Shabanowitz J Hunt DF Allis CD 《The Journal of biological chemistry》2009,284(2):1064-1074
Histone proteins contain epigenetic information that is encoded both in the relative abundance of core histones and variants and particularly in the post-translational modification of these proteins. We determined the presence of such variants and covalent modifications in seven tissue types of the anuran Xenopus laevis, including oocyte, egg, sperm, early embryo equivalent (pronuclei incubated in egg extract), S3 neurula cells, A6 kidney cells, and erythrocytes. We first developed a new robust method for isolating the stored, predeposition histones from oocytes and eggs via chromatography on heparin-Sepharose, whereas we isolated chromatinized histones via conventional acid extraction. We identified two previously unknown H1 isoforms (H1fx and H1B.Sp) present on sperm chromatin. We immunoblotted this global collection of histones with many specific post-translational modification antibodies, including antibodies against methylated histone H3 on Lys(4), Lys(9), Lys(27), Lys(79), Arg(2), Arg(17), and Arg(26); methylated histone H4 on Lys(20); methylated H2A and H4 on Arg(3); acetylated H4 on Lys(5), Lys(8), Lys(12), and Lys(16) and H3 on Lys(9) and Lys(14); and phosphorylated H3 on Ser(10) and H2A/H4 on Ser(1). Furthermore, we subjected a subset of these histones to two-dimensional gel analysis and subsequent immunoblotting and mass spectrometry to determine the global remodeling of histone modifications that occurs as development proceeds. Overall, our observations suggest that each metazoan cell type may have a unique histone modification signature correlated with its differentiation status. 相似文献
119.
Isolation and characterization of cellulose-degrading bacteria from the deep subsurface of the Homestake gold mine,Lead, South Dakota,USA 总被引:3,自引:0,他引:3
Gurdeep Rastogi Geetha L. Muppidi Raghu N. Gurram Akash Adhikari Kenneth M. Bischoff Stephen R. Hughes William A. Apel Sookie S. Bang David J. Dixon Rajesh K. Sani 《Journal of industrial microbiology & biotechnology》2009,36(4):585-598
The present study investigated the cultivable mesophilic (37°C) and thermophilic (60°C) cellulose-degrading bacterial diversity
in a weathered soil-like sample collected from the deep subsurface (1.5 km depth) of the Homestake gold mine in Lead, South
Dakota, USA. Chemical characterization of the sample by X-ray fluorescence spectroscopy revealed a high amount of toxic heavy
metals such as Cu, Cr, Pb, Ni, and Zn. Molecular community structures were determined by phylogenetic analysis of 16S rRNA
gene sequences retrieved from enrichment cultures growing in presence of microcrystalline cellulose as the sole source of
carbon. All phylotypes retrieved from enrichment cultures were affiliated to Firmicutes. Cellulose-degrading mesophilic and thermophilic pure cultures belonging to the genera Brevibacillus, Paenibacillus, Bacillus, and Geobacillus were isolated from enrichment cultures, and selected cultures were studied for enzyme activities. For a mesophilic isolate
(DUSELG12), the optimum pH and temperature for carboxymethyl cellulase (CMCase) were 5.5 and 55°C, while for a thermophilic
isolate (DUSELR7) they were 5.0 and 75°C, respectively. Furthermore, DUSELG12 retained about 40% CMCase activity after incubation
at 60°C for 8 h. Most remarkably, thermophilic isolate, DUSELR7 retained 26% CMCase activity at 60°C up to a period of 300 h.
Overall, the present work revealed the presence of different cellulose-degrading bacterial lineages in the unique deep subsurface
environment of the mine. The results also have strong implications for biological conversion of cellulosic agricultural and
forestry wastes to commodity chemicals including sugars. 相似文献
120.
Yellappa S Seetharamappa J Rogers LM Chitta R Singhal RP D'Souza F 《Bioconjugate chemistry》2006,17(6):1418-1425
The binding of nucleic acids by water-soluble cobalt(II) tetrakis-N-methylpyridyl porphyrin, (TMPyP)Co, and its highly electron-deficient derivative cobalt(II) tetrakis-N-methyl pyridyl-beta-octabromoporphyrin, (Br(8)TMPyP)Co, was investigated by UV-visible absorption, circular dichroism (CD), and electrochemical and gel electrophoresis methods. The changes of the absorption spectra during the titration of these complexes with polynucleotides revealed a shift in the absorption maxima and a hypochromicity of the porphyrin Soret bands. The intrinsic binding constants were found to be in the range of 10(5)-10(6) M(-1). These values were higher for the more electron-deficient (Br(8)TMPyP)Co. Induced CD bands were noticed in the Soret region of the complexes due to the interaction of these complexes with different polynucleotides, and an analysis of the CD spectra supported a mainly external mode of binding. Electrochemical studies revealed the cleavage of polynucleotides by (TMPyP)Co and (Br(8)TMPyP)Co in the presence of oxygen preferentially at the A-T base pair region. Gel electrophoresis experiments further supported the cleavage of nucleic acids. The results indicate that the beta-pyrrole brominated porphyrin, (Br(8)TMPyP)Co, binds strongly and cleaves nucleic acids efficiently as compared with (TMPyP)Co. This electrolytic procedure offers a unique tool in biotechnology for cleaving double-stranded DNA with specificity at the A-T regions. 相似文献