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61.
Novobiocin analogs lacking labile glycosidic ether have been designed, synthesized and evaluated for Hsp90 inhibitory activity. Replacement of the synthetically complex noviose sugar with simple aromatic side chains produced analogs that maintain moderate cytotoxic activity against MCF7 and SkBR3 breast cancer cell-lines. Rationale for the preparation of des-noviose novobiocin analogs in addition to their synthesis and biological evaluation are presented herein. 相似文献
62.
Alien fishes are considered a major threat to aquatic biodiversity in South Africa, yet relatively little regional information on their biology and ecology is available for many of these species. Seasonal changes in the diet of the bluegill Lepomis macrochirus in Howieson’s Poort Dam, Grahamstown, were assessed during summer and winter in 2014–2015, using stomach content analysis. In winter, juvenile and adult fish diets were dominated by crustacean zooplankton and insects, respectively. In summer, juvenile fish fed on crustaceans and insects, whereas adults consumed mostly fish eggs, indicating a potential impact by these invasive fish on native fish through oophagy. 相似文献
63.
Molecular phylogenetic and biogeochemical studies of sulfate-reducing bacteria in the rhizosphere of spartina alterniflora 总被引:1,自引:0,他引:1
Hines ME Evans RS Sharak Genthner BR Willis SG Friedman S Rooney-Varga JN Devereux R 《Applied and environmental microbiology》1999,65(5):2209-2216
The population composition and biogeochemistry of sulfate-reducing bacteria (SRB) in the rhizosphere of the marsh grass Spartina alterniflora was investigated over two growing seasons by molecular probing, enumerations of culturable SRB, and measurements of SO42- reduction rates and geochemical parameters. SO42- reduction was rapid in marsh sediments with rates up to 3.5 &mgr;mol ml-1 day-1. Rates increased greatly when plant growth began in April and decreased again when plants flowered in late July. Results with nucleic acid probes revealed that SRB rRNA accounted for up to 43% of the rRNA from members of the domain Bacteria in marsh sediments, with the highest percentages occurring in bacteria physically associated with root surfaces. The relative abundance (RA) of SRB rRNA in whole-sediment samples compared to that of Bacteria rRNA did not vary greatly throughout the year, despite large temporal changes in SO42- reduction activity. However, the RA of root-associated SRB did increase from <10 to >30% when plants were actively growing. rRNA from members of the family Desulfobacteriaceae comprised the majority of the SRB rRNA at 3 to 34% of Bacteria rRNA, with Desulfobulbus spp. accounting for 1 to 16%. The RA of Desulfovibrio rRNA generally comprised from <1 to 3% of the Bacteria rRNA. The highest Desulfobacteriaceae RA in whole sediments was 26% and was found in the deepest sediment samples (6 to 8 cm). Culturable SRB abundance, determined by most-probable-number analyses, was high at >10(7) ml-1. Ethanol utilizers were most abundant, followed by acetate utilizers. The high numbers of culturable SRB and the high RA of SRB rRNA compared to that of Bacteria rRNA may be due to the release of SRB substrates in plant root exudates, creating a microbial food web that circumvents fermentation. 相似文献
64.
Codon fitnesses for chloroplast genes were estimated using the relative
synonymous codon use of psbA, which has a different pattern of codon use
than other chloroplast genes and is the major translation product of the
chloroplast. These estimates were used to calculate the codon adaptation
index (CAI) of chloroplast genes from Marchantia polymorpha, Nicotiana
tabacum, and Chlamydomonas reinhardtii. The genes with the highest CAI
values in M. polymorpha correspond to those that are expressed at the
highest levels. The rate of divergence between M. polymorpha and both C.
reinhardtii and N. tabacum is inversely related to the CAI value of the M.
polymorpha gene. The data suggest that selection is acting on the
synonymous codon use of the highly expressed genes of the M. polymorpha
chloroplast genome. The data set is inconclusive about N. tabacum genes,
but, as there is a weaker correspondence between CAI value and expression
level, it suggests that selection is not operating in this lineage.
相似文献
65.
Babu BV Leela BL Kusuma YS 《Anthropologischer Anzeiger; Bericht über die biologisch-anthropologische Literatur》2002,60(2):169-174
Sickle cell disease is observed to occur in significantly high frequencies amongst the tribes of India. It has surged to the fore as an important public health problem among tribal groups, which needs serious attention. This paper presents the distribution of this abnormal genetic problem among scheduled tribes of India, in general and among those of Andhra Pradesh and Orissa states, in detail. Though the prevalence of sickle cell trait is high, the sickle cell disease cases are found to be very low, since all these surveys are made among adults. Most of the sickle cell disease cases might have expired during their early states. Hence, it is attempted to estimate the expected frequencies of disease cases from HbS gene frequencies. Estimations were also made by considering higher levels of inbreeding among these populations. 相似文献
66.
Dey G Palit S Banerjee R Maiti BR 《Journal of industrial microbiology & biotechnology》2002,28(4):193-200
A maltooligosaccharide-forming amylase that hydrolyzes starch into maltotriose and maltopentaose was found in the culture
filtrate of a strain of Bacillus circulans GRS 313 isolated from local soil. The enzyme was purified by organic solvent fractionation, Sephadex G-100 gel filtration
and CM-Sephadex column chromatography. Optimum pH and temperature of amylase were evaluated using response surface methodology
(RSM) and were found to be 48°C and 4.9, respectively. The enzyme was stable up to 60°C and its pH stability was in the range
of 5.0–8.0. The K
m and V
max of the amylase with starch were 11.66 mg/ml and 68.97 U, respectively, and the energy of activation, E
a, was 7.52 kcal/mol. Dextrin inhibited the enzyme competitively, with a K
i of 6.1 mg/ml, and glucose caused noncompetitive inhibition with a K
i of 9.5 mg/ml. The enzyme was inhibited by Hg2+, Mn2+, Fe3+ and Cu2+ and enhanced by Co2+ and Mg2+. EDTA reversed the inhibitory effect of the metals. Paper chromatographic and high-performance liquid chromatography analysis
of the products of the amylolytic reaction showed the presence of maltotriose, maltotetraose, maltopentaose, maltose and glucose
in the starch hydrolysate. Journal of Industrial Microbiology & Biotechnology (2002) 28, 193–200 DOI: 10.1038/sj/jim/7000220
Received 11 December 2000/ Accepted in revised form 22 October 2001 相似文献
67.
Polarization Orientation,Piezoelectricity, and Energy Harvesting Performance of Ferroelectric PVDF‐TrFE Nanotubes Synthesized by Nanoconfinement 下载免费PDF全文
1D nanostructures of soft ferroelectric materials exert promising potential in the fields of energy harvesting and flexible and printed nanoelectronics. Here, improved piezoelectric properties, energy‐harvesting performance, lower coercive fields, and the polarization orientation of poly(vinylidene fluoride–trifluoroethylene) (PVDF‐TrFE) nanotubes synthesized with nanoconfinement effect are reported. X‐ray diffraction (XRD) patterns of the nanotubes show the peak corresponding to the planes of (110)/(200), which is a signature of ferroelectric beta phase formation. Piezoforce spectroscopy measurements on the free‐standing horizontal nanotubes bundles reveal that the effective polarization direction is oriented at an inclination to the long axis of the nanotubes. The nanotubes exhibit a coercive field of 18.6 MV m?1 along the long axis and 40 MV m?1 (13.2 MV m?1 considering the air gap) in a direction perpendicular to the long axis, which is lower than the film counterpart of 50 MV m?1. The poled 200 nm nanotubes, with 40% reduction in poling field, give larger piezoelectric d33 coefficient values of 44 pm V?1, compared to poled films (≈20 pm V?1). The ferroelectric nanotubes deliver superior energy harvesting performance with an output voltage of ≈4.8 V and power of 2.2 μW cm?2, under a dynamic compression pressure of 0.075 MPa at 1 Hz. 相似文献
68.
Yian Kim Tan Caroline M. Kusuma Hao A. Vu Kenneth Alibek 《Biochemical and biophysical research communications》2009,379(2):293-297
Autophagy is an evolutionary conserved intracellular process whereby cells break down long-lived proteins and organelles. Accumulating evidences suggest increasing physiological significance of autophagy in pathogenesis of infectious diseases. Anthrax lethal toxin (LT) exerts its influence on numerous cells and herein, we report a novel effect of LT-induced autophagy on mammalian cells. Several autophagy biochemical markers including LC3-II conversion, increased punctuate distribution of GFP-LC3 and development of acidic vesicular organelles (AVO) were detected in cells treated with LT. Analysis of individual LT component revealed a moderate increase in LC3-II conversion for protective antigen-treated cells, whereas the LC3-II level in lethal factor-treated cells remained unchanged. In addition, our preliminary findings suggest a protective role of autophagy in LT intoxication as autophagy inhibition resulted in accelerated cell death. This study presents a hitherto undescribed effect of LT-induced autophagy on cells and provides the groundwork for future studies on the implication of autophagy in anthrax pathogenesis. 相似文献
69.
70.