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371.
HPLC and Inhibitory Indirect ELISA (I.I. ELISA) methods for quantitation of aflatoxins (AF) in human urine were compared in terms of specificity, sensitivity, easiness and cost. I.I. ELISA was optimized in kind of antibody in use, type of plastic plate, adduct synthesis technique, peroxidase and antibody dilutions, etc. Both polyclonal (Cuban) and monoclonal (British) anti-AF antibodies were statistically studied and the process was standardized. HPLC and electrophoresis were performed while synthetizing AFB(1)-DNA and AFB(1)-Cl-Ovalbumin (AFB(1)-Cl-Ov) adducts. Costar polystyrene plate had the best adherence. Optimum coating dilution was 10 ng of AFB(1)-Cl-Ov per well. Dilutions of 1:1000 of monoclonal antibody from purified culture or 1:300 from monoclonal antibody from tissue culture and 1:1000 of peroxidase anti-mouse conjugate were the best. Optimum separation with HPLC was obtained isocratically with 60% MeOH and 40% distilled water mobile phase. ELISA had a sensitivity of 1 pg mL(-1) AFB(1) and HPLC sensitivity was 0.1 ng mL(-1) AFB(1) with fluorescence detector and 4.5 ng mL(-1) with UV detector. Monoclonal antibody gave more accurate results for determination of free and adducted AFB(1) in urine analysis. 相似文献
372.
A very active cell-free translation system was prepared from 4–5-day-old embryonic axes of melon (Cucumis melo L.), a species whose dry seeds contain a powerful translational inhibitor. The system was optimized for Mg2+, K+, NH4+, high speed supernatant, total wheat germ tRNA, time and temperature. Using a 30 000 × g supernatant, the system translates endogenous messengers and polyuridylic acid very efficiently. Melon ribosomes were inhibited in vitro by several well-known eukaryotic inhibitors including melonin, the protein inhibitor present in the dry seeds of C. melo. Our results suggest that the protein inhibitor does not affect the activity of melon ribosomes neither in vivo nor during their isolation. 相似文献
373.
Paragus hyalopteri Marcos-García et Rojo n. sp. is described. The new species was caught in Alicante province (SE Spain). This species is morphologically close toParagus quadrifasciatus Meigen, 1822. It was collected on several species of fruit trees of the genusPrunus, upon the mealy plum aphidHyalopterus pruni (Geoffroy, 1762). 相似文献
374.
Nora M. Urquiza Silvia G. Manca María A. Moyano Raquel Arrieta Dellmans Luis Lezama Teófilo Rojo Luciana G. Naso Patricia A. M. Williams Evelina G. Ferrer 《Biometals》2010,23(2):255-264
Methimazole (MeimzH) is an anti-thyroid drug and the first choice for patients with Grave’s disease. Two new copper(II) complexes of this drug: [Cu(MeimzH)2(NO3)2].0.5H2O and [Cu(MeimzH)2(H2O)2](NO3)2·H2O were synthesized and characterized by elemental analysis, dissolution behavior, thermogravimetric analysis and UV-vis, diffuse reflectance, FTIR and EPR spectroscopies. As it is known that copper(II) cation can act as an inhibitor of alkaline phosphatase (ALP), the inhibitory effect of methimazole and its copper(II) complexes on ALP activity has also been investigated. 相似文献
375.
The level of the pUB110 replication initiator protein is autoregulated, which provides an additional control for plasmid copy number. 总被引:5,自引:0,他引:5 下载免费PDF全文
Plasmids control their copy number by limiting the amount of the initiator for DNA replication. The plasmid pUB110 initiator protein is termed RepU. Expression of the pUB110 repU gene is controlled by two antisense RNAs that interfere with repU mRNA translation. Genetic evidence suggests that Rep protein levels may be regulated by additional uncharacterized mechanisms. The repU gene product was radiolabeled and purified by monitoring the radioactive label. RepU overproduction was performed in cells containing the plasmid leading strand replication origin (dso), to allow for a putative inactivation of RepU. Polypeptides with apparent molecular masses of 42 (RepU*) and 39 (RepU) kDa were purified, both having the N-terminal sequence expected for the repU gene. The RepU/RepU* protein mixture bound specifically to dso. At low protein concentrations, about six RepU/RepU* protomers bound to the dso region. At higher concentrations, an extended nucleoprotein complex was formed. The promoter for the repU gene was localized downstream of the dso region. The results suggest that the extended RepU/RepU*-dso DNA complex interferes with repU promoter utilization. This provides an additional copy number control by limiting RepU concentration. Our results suggest that during replication the RepU protein might be converted into an inactive RepU-RepU* hetero-oligomer, further limiting the amount of RepU protein available for replication initiation. 相似文献
376.
Lázaro Molina Ruggero La Rosa Juan Nogales Fernando Rojo 《Environmental microbiology》2019,21(11):4446-4459
When the soil bacterium Pseudomonas putida grows in a complete medium, it prioritizes the assimilation of preferred carbon sources, optimizing its metabolism and growth. This regulatory process is orchestrated by the Crc and Hfq proteins. The present work examines the changes that occur in metabolic fluxes when the crc gene is inactivated and cells grow exponentially in LB complete medium. Analyses were performed at three different moments during exponential growth, examining the assimilation rates for the compounds present in LB, changes in the proteome, and the changes in metabolic fluxes predicted by the iJN1411 metabolic model for P. putida KT2440. During the early exponential phase, consumption rates for sugars, many organic acids and most amino acids were higher in a Crc-null strain than in the wild type, leading to an overflow of the metabolic pathways and the leakage of pyruvate and acetate. These accelerated consumption rates decreased during the mid-exponential phase, when cells mostly used sugars and alanine. At later times, pyruvate was recovered from the medium and utilized. The higher consumption rates of the Crc-null strain reduced the growth rate. The lack of the Crc/Hfq regulatory system thus led to unbalanced metabolism with poorly optimized metabolic fluxes. 相似文献
377.
Juan F. Linares Renata Moreno Alicia Fajardo Laura Martínez‐Solano Ricardo Escalante Fernando Rojo José L. Martínez 《Environmental microbiology》2010,12(12):3196-3212
The capacity of a bacterial pathogen to produce a disease in a treated host depends on the former's virulence and resistance to antibiotics. Several scattered pieces of evidence suggest that these two characteristics can be influenced by bacterial metabolism. This potential relationship is particularly important upon infection of a host, a situation that demands bacteria adapt their physiology to their new environment, making use of newly available nutrients. To explore the potential cross‐talk between bacterial metabolism, antibiotic resistance and virulence, a Pseudomonas aeruginosa model was used. This species is an important opportunistic pathogen intrinsically resistant to many antibiotics. The role of Crc, a global regulator that controls the metabolism of carbon sources and catabolite repression in Pseudomonas, was analysed to determine its contribution to the intrinsic antibiotic resistance and virulence of P. aeruginosa. Using proteomic analyses, high‐throughput metabolic tests and functional assays, the present work shows the virulence and antibiotic resistance of this pathogen to be linked to its physiology, and to be under the control (directly or indirectly) of Crc. A P. aeruginosa strain lacking the Crc regulator showed defects in type III secretion, motility, expression of quorum sensing‐regulated virulence factors, and was less virulent in a Dictyostelium discoideum model. In addition, this mutant strain was more susceptible to beta‐lactams, aminoglycosides, fosfomycin and rifampin. Crc might therefore be a good target in the search for new antibiotics. 相似文献
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380.
Reyes-Velázquez WP Isaías Espinoza VH Rojo F Jiménez-Plasencia C de Lucas Palacios E Hernández-Góbora J Ramírez-Alvarez A 《Revista iberoamericana de micología》2008,25(3):182-185
The aim of this study was to evaluate the chemical composition, mold count and mycotoxin contamination of corn silage collected during a six month-period. The results indicated that the chemical composition and the physicochemical parameters evaluated did not show significant variation during the sampling time. Fungal count on RBC ranged from 1.7 x 10(3) to 9 x 10e8 CFU/g. Mucor, Penicillium and Aspergillus spp. were the most frequent fungal species in the corn silage. Fusarium count ranged from 1.6 x 10(3) to 1.6 x 10e8 CFU/g in Nash Snyder culture media. Aflatoxin B, fumonisins, ochratoxin A, ochratoxin B, deoxynivalenol, and zearalenone were detected throughout the period of corn silage maintenance (100% positive samples). However, only deoxynivalenol levels were higher than the maximum limit recommended by the FDA. 相似文献