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191.
Mark?A?HerbertEmail author Catriona?JE?Beveridge David?McCormick Emmelien?Aten Nicola?Jones Lori?AS?Snyder Nigel?J?Saunders 《BMC microbiology》2005,5(1):31
Background
Streptococcus agalactiae (Group B Streptococcus; GBS) is a major contributor to obstetric and neonatal bacterial sepsis. Serotype III strains cause the majority of late-onset sepsis and meningitis in babies, and thus appear to have an enhanced invasive capacity compared with the other serotypes that cause disease predominantly in immunocompromised pregnant women. We compared the serotype III and V whole genome sequences, strains NEM316 and 2603VR respectively, in an attempt to identify genetic attributes of strain NEM316 that might explain the propensity of strain NEM316 to cause late-onset disease in babies. Fourteen putative pathogenicity islands were described in the strain NEM316 whole genome sequence. Using PCR- and targeted microarray- strategies, the presence of these islands were assessed in a diverse strain collection including 18 colonizing isolates from healthy pregnant women, and 13 and 8 invasive isolates from infants with early- and late-onset sepsis, respectively. 相似文献192.
The assignment of the different infrared continuum absorbance changes observed in the 3000-1800-cm(-1) region during the bacteriorhodopsin photocycle
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The bleach continuum in the 1900-1800-cm(-1) region was reported during the photocycle of bacteriorhodopsin (bR) and was assigned to the dissociation of a polarizable proton chain during the proton release step. More recently, a broad band pass filter was used and additional infrared continua have been reported: a bleach at >2700 cm(-1), a bleach in the 2500-2150-cm(-1) region, and an absorptive behavior in the 2100-1800-cm(-1) region. To fully understand the importance of the hydrogen-bonded chains in the mechanism of the proton transport in bR, a detailed study is carried out here. Comparisons are made between the time-resolved Fourier transform infrared spectroscopy experiments on wild-type bR and its E204Q mutant (which has no early proton release), and between the changes in the continua observed in thermally or photothermally heated water (using visible light-absorbing dye) and those observed during the photocycle. The results strongly suggest that, except for the weak bleach in the 1900-1800-cm(-1) region and >2500 cm(-1), there are other infrared continua observed during the bR photocycle, which are inseparable from the changes in the absorption of the solvent water molecules that are photothermally excited via the nonradiative relaxation of the photoexcited retinal chromophore. A possible structure of the hydrogen-bonded system, giving rise to the observed bleach in the 1900-1800-cm(-1) region and the role of the polarizable proton in the proton transport is discussed. 相似文献
193.
Characteristics of selenazolidine prodrugs of selenocysteine: toxicity, selenium levels, and glutathione peroxidase induction in A/J mice 总被引:1,自引:0,他引:1
We have previously reported the synthesis and characterization of two new classes of selenazolidine-4(R)-carboxylic acids (2-oxo and 2-methyl-SCAs) (OSCA and MSCA, respectively), as well as the "parent" compound, selenazolidine-4(R)-carboxylic acid (SCA, selenaproline). These compounds were designed as prodrugs of L-selenocysteine with potential application in cancer chemoprevention or other clinical uses. We will be exploring the chemopreventive activity of the new compounds in the well-established A/J mouse model of tobacco-induced lung carcinogenesis. The objectives of the present study were to investigate several fundamental biochemical endpoints after selenazolidine administration compared with other selenium-containing agents. Groups of mice were fed either AIN-76A diet alone or the diet supplemented with the following selenium compounds (ppm Se): sodium selenite (5), L-selenomethionine (3.75), L-selenocystine (15), Se-methyl-L-selenocysteine (3), MSCA (5, 10, or 15), OSCA (5, 10, or 15), or SCA (5, 10, or 15). After 28 days of supplementation, toxicity of the selenazolidines was not evident, as measured by outward appearance and behavior, body and organ weight changes, and histological evaluation of liver and lung tissue. Select treatment groups showed significant increases in selenium levels in blood and tissues. Increased activity of selenium-dependent glutathione peroxidase (GPx) in blood and liver illustrated that the selenazolidines provided a source of biologically-available selenium. 相似文献
194.
El-Morsy el-SM 《Mycologia》2004,96(6):1183-1189
Thirty-two fungal species were isolated from a polluted watercourse near the Talkha fertilizer plant, Mansoura Province, Egypt. Aspergillus niger, A. flavus, Cunninghamella echinulata and Trichoderma koningii were isolated frequently. On the basis of its frequency, Cunninghamella echinulata was chosen for biosorption studies. Free and immobilized biomass of C. echinulata sequestered ions in this decreasing sequence is: Pb >Cu >Zn. The effects of biomass concentration, pH and time of contact were investigated. The level of ion uptake rose with increasing biomass. The maximum uptake for lead (45 mg/g), copper (20 mg/g) and zinc (18.8 mg/g) occurred at 200 mg/L biomass. The uptake rose with increasing pH up to 4 in the case of Pb and 5 in the case of Cu and Zn. Maximum uptake for all metals was achieved after 15 min. Ion uptake followed the Langmuir adsorption model, permitting the calculation of maximum uptake and affinity coefficients. Treatment of C. echinulata biomass with NaOH improved biosorbent capacity, as did immobilization with alginate. Immobilized biomass could be regenerated readily by treatment with dilute HCl. The biomass-alginate complex efficiently removed Pb, Zn and Cu from polluted water samples. Therefore,Cunninghamella echinulata could be employed either in free or immobilized form as a biosorbent of metal ions in waste water. 相似文献
195.
We have studied the effect of monomerization of the purple membrane lattice, as well as removal of 75% of the lipids, on the binding properties of Eu(3+) ions. We found that delipidation and monomerization do not cause the cations to lose their binding ability to the protein. This suggests that the three most strongly bound Eu(3+) cations do not bind to the lipids, but directly bind to the protein. Furthermore, we found that delipidation actually causes a slight increase in the binding affinity. This is likely a result of reduced aggregation of europium-regenerated bacteriorhodopsin (bR) upon lipid removal causing more exposure of the binding sites to the Eu(3+) cations. These results, taken with those from our previous publication [Heyes and El-Sayed, Biophys. J. 85 (2003) 426-434], might suggest that the cations remain bound upon delipidation of bR, but have no effect on the function. This is discussed with respect to the role of cations in the function of native bR. 相似文献
196.
Performance of irradiated Teia anartoides (Lepidoptera: Lymantriidae) in urban Auckland, New Zealand
Suckling DM Charles J Allan D Chaggan A Barrington A Burnip GM El-Sayed AM 《Journal of economic entomology》2005,98(5):1531-1538
The Australian moth Teia anartoides Walker has been the target of a major eradication program in Auckland, New Zealand. Information on cold torpor and dispersal was needed to help interpret catches of sterile and wild males in female-baited delta traps operated in a grid of up to 1,696 traps at 500-m spacings across the city. Laboratory experiments indicated male flight was enabled at temperatures above 17 degrees C (confirmed by field trapping of wild and recaptured moths). Male survival in the field or in field cages was determined to be limited to approximately 4 d. Sterilization of males for dispersal studies was achieved by exposing male pupae to either 160 or 100 Gy by using 1.25 MeV gamma rays from a Cobalt source, before release as fluorescent-dyed emerged adults. Dispersal was determined by recapture of males in the trapping grid of 1,696 delta traps baited with virgin female moths and placed at spacings of 50-500 m. Irradiated sterile males dispersed up to a maximum recorded distance of 4,500 m (160 Gy) and 10,000 m (100 Gy). At 100 Gy, the median dispersal distance was 300 m, with 90% of males dispersing 1,600 m or less. 相似文献
197.
Walaa M. El-Husseiny Magda A.-A. El-Sayed Esam R. Ahmed Alaa A.-M. Abdel-Aziz 《Journal of enzyme inhibition and medicinal chemistry》2018,33(1):507-518
New α,β-unsaturated ketones 4a,b; 5a–c; and 6a,b; as well as 4-H pyran 7; pyrazoline 8a,b; isoxazoline 9; pyridine 10–11; and quinoline-4-carboxylic acid 12a,b derivatives were synthesized and evaluated for in vitro antitumour activity against HepG2, MCF-7, HeLa, and PC-3 cancer cell lines. Antioxidant activity was investigated by the ability of these compounds to scavenge the 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS?+). Compounds 6a, 6b, 7, and 8b exhibited potent antitumour activities against all tested cell lines with [IC50] ?5.5–18.1 µΜ), in addition to significantly high ABTS?+ scavenging activities. In vitro EGFR kinase assay for 6a, 6b, 7, and 8b as the most potent antitumour compounds showed that; compounds 6b, and 7 exhibited worthy EGFR inhibition activity with IC50 values of 0.56 and 1.6?µM, respectively, while compounds 6a and 8b showed good inhibition activity with IC50 values of 4.66 and 2.16?µM, respectively, compared with sorafenib reference drug (IC50?=?1.28?µM). Molecular modelling studies for compounds 6b, 7, and 8b were conducted to exhibit the binding mode towards EGFR kinase, which showed similar interaction with erlotinib. 相似文献
198.
Studies of cation binding in ZnCl2-regenerated bacteriorhodopsin by x-ray absorption fine structures: effects of removing water molecules and adding Cl- ions.
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The binding of Zn2+ in Zn2+-regenerated bacteriorhodopsin (bR) was studied under various conditions by x-ray absorption fine structures (XAFS). The 0.9:1 and 2:1 Zn2+:bR samples gave similar XAFS spectra, suggesting that Zn2+ might have only one strong binding site in bR. It was found that in aqueous bR solution, Zn2+ has an average of six oxygen or nitrogen ligands. Upon drying, two ligands are lost, suggesting the existence of two weakly bound water ligands near the cation-binding site in bacteriorhodopsin. When excess Cl- ions were present before drying in the Zn2+-regenerated bR samples, it was found that two of the ligands were replaced by Cl- ions in the dried film, whereas two remain unchanged. The above observations suggest that Zn2+ has three types of ligands in regenerated bR (referred to as types I, II, and III). Type I ligands are strongly bound. These ligands cannot be removed by drying or by exchanging with Cl- ions. Type II ligands cannot be removed by drying, but can be replaced by Cl- ligands. Type III ligands are weakly bound to the metal cation and are most likely water molecules that can be removed by evaporation under vacuum or by drying with anhydrous CaSO4. The results are discussed in terms of the possible structure of the strongly binding site of Zn2+ in bR. 相似文献
199.
200.
Ahmed F. Halim El-Sayed S. Mansour Farid A. Badria Jürgen Ziesche Ferdinand Bohlmann 《Phytochemistry》1984,23(4):914-915
The leaves of Magnolia grandiflora afforded in addition to costunolide diepoxide and parthenolide a guaianolide named magnograndiolide. 相似文献