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111.
Repeating sequences and gene duplication in proteins 总被引:13,自引:0,他引:13
A D McLachlan 《Journal of molecular biology》1972,64(2):417-437
The theory that proteins have evolved by repeated internal duplication of short segments of polypeptide chains has been tested by looking for repeats and near repeats in over 50 different proteins, many of them of known structure. The probability that the observed repeats could arise by chance has been calculated. 相似文献
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D Robin Taylor Piush Mandhane Justina M Greene Robert J Hancox Sue Filsell Christene R McLachlan Avis J Williamson Jan O Cowan Andrew D Smith Malcolm R Sears 《Respiratory research》2007,8(1):82-9
Background
Exhaled nitric oxide (FENO) measurements are used as a surrogate marker for eosinophilic airway inflammation. However, many constitutional and environmental factors affect FENO, making it difficult to devise reference values. Our aim was to evaluate the relative importance of factors affecting FENO in a well characterised adult population.Methods
Data were obtained from 895 members of the Dunedin Multidisciplinary Health and Development Study at age 32. The effects of sex, height, weight, lung function indices, smoking, atopy, asthma and rhinitis on FENO were explored by unadjusted and adjusted linear regression analyses.Results
The effect of sex on FENO was both statistically and clinically significant, with FENO levels approximately 25% less in females. Overall, current smoking reduced FENO up to 50%, but this effect occurred predominantly in those who smoked on the day of the FENO measurement. Atopy increased FENO by 60%. The sex-related differences in FENO remained significant (p < 0.001) after controlling for all other significant factors affecting FENO.Conclusion
Even after adjustment, FENO values are significantly different in males and females. The derivation of reference values and the interpretation of FENO in the clinical setting should be stratified by sex. Other common factors such as current smoking and atopy also require to be taken into account. 相似文献114.
Guillermo A. Gomez Robert W. McLachlan Selwin K. Wu Benjamin J. Caldwell Elliott Moussa Suzie Verma Michele Bastiani Rashmi Priya Robert G. Parton Katharina Gaus Jan Sap Alpha S. Yap 《Molecular biology of the cell》2015,26(7):1249-1262
Cell–cell adhesion couples the contractile cortices of epithelial cells together, generating tension to support a range of morphogenetic processes. E-cadherin adhesion plays an active role in generating junctional tension by promoting actin assembly and cortical signaling pathways that regulate myosin II. Multiple myosin II paralogues accumulate at mammalian epithelial cell–cell junctions. Earlier, we found that myosin IIA responds to Rho-ROCK signaling to support junctional tension in MCF-7 cells. Although myosin IIB is also found at the zonula adherens (ZA) in these cells, its role in junctional contractility and its mode of regulation are less well understood. We now demonstrate that myosin IIB contributes to tension at the epithelial ZA. Further, we identify a receptor type-protein tyrosine phosphatase alpha–Src family kinase–Rap1 pathway as responsible for recruiting myosin IIB to the ZA and supporting contractile tension. Overall these findings reinforce the concept that orthogonal E-cadherin–based signaling pathways recruit distinct myosin II paralogues to generate the contractile apparatus at apical epithelial junctions. 相似文献
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Deirdre H. McLachlan Colin Brownlee Alison R. Taylor Richard J. Geider Graham J. C. Underwood 《Journal of phycology》2009,45(3):592-599
Motility of estuarine epipelic (mud‐inhabiting) diatoms is an important adaptation to living in biofilms present within fine sediments. Motility allows cells to migrate within the photic zone in response to a wide range of environmental stimuli. The motile responses of two species of benthic diatoms to photon fluence rates and spectral quality were investigated. Cultures of Navicula perminuta (Grunow) in van Heurck and Cylindrotheca closterium (Ehrenb.) J. C. Lewin et Reimann both exhibited photoaccumulation at ~200 μmol · m?2 · s?1 and photodispersal from photon flux densities (PFDs) of ~15 μmol · m?2 · s?1. Photokinesis (changing cell speed) contributed toward photodispersal for both species, and red light (λ = 681–691 nm) was most effective at inducing this process. N. perminuta showed a phototactic (directional) response, with active movement in response to a light gradient. Although this response was exhibited in white light, these directional responses were only elicited by wavelengths from 430 to 510 nm. In contrast, C. closterium did not exhibit phototaxis under any light conditions used in this study. Motile benthic diatoms thus exhibit complex and sophisticated responses to light quantity and quality, involving combinations of photokinesis and phototaxis, which can contribute toward explaining the patterns of large‐scale cell movements observed in natural estuarine biofilms. 相似文献
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Michael J. Blum Erin Knapke Jason S. McLachlan Sunny B. Snider Colin J. Saunders 《Conservation Genetics》2010,11(5):1885-1898
Hybridization is an evolutionary mechanism capable of enhancing adaptive potential, especially among species in fragmented
or disturbed ecosystems like coastal marshes. In this study, we evaluated whether hybridization might influence adaptive responses
in coastal marshes that are susceptible to the effects of global environmental change. To do so, we examined the extent and
nature of hybridization between Schoenoplectus americanus and S. pungens, two ecologically dominant sedges in low-lying marshes across Chesapeake Bay (USA). Observed patterns of variation at genetically
based morphological traits, cpDNA and nuclear microsatellite markers confirm that introgressive hybridization occurs between
the two species. Comparisons of microsatellite and cpDNA profiles found that hybridization is reciprocal, although a disproportionate
number of hybrids exhibit genomic asymmetries favoring S. americanus. AIC model selection consistently identified latitude as the strongest explanatory variable for the distribution of parental
species, although discriminant analysis indicated that distributions also correspond to variation in environmental conditions.
Discriminant analysis further indicated that ecological correlates of hybrid and S. americanus genotypes are similar, but not uniformly so. These findings indicate that the boundary between S. americanus and S. pungens is porous, and that hybridization could influence responses of one or both species to changing environmental regimes. 相似文献
120.
Measurement of urinary oxypurinol by high performance liquid chromatography–tandem mass spectrometry
Sophie L. Stocker Michael E. Franklin Jacqueline M. Anderson Peter I. Pillans Kenneth M. Williams Andrew J. McLachlan Richard O. Day Paul J. Taylor 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2010,878(25):2363-2368
Oxypurinol is the active metabolite of allopurinol which is used to treat hyperuricaemia associated with gout. Both oxypurinol and allopurinol inhibit xanthine oxidase which forms uric acid from xanthine and hypoxanthine. Plasma oxypurinol concentrations vary substantially between individuals and the source of this variability remains unclear. The aim of this study was to develop an HPLC-tandem mass spectrometry method to measure oxypurinol in urine to facilitate the study of the renal elimination of oxypurinol in patients with gout. Urine samples (50 μL) were prepared by dilution with a solution of acetonitrile/methanol/water (95/2/3, v/v; 2 mL) that contained the internal standard (8-methylxanthine; 1.5 mg/L), followed by centrifugation. An aliquot (2 μL) was injected. Chromatography was performed on an Atlantis HILIC Silica column (3 μm, 100 mm × 2.1 mm, Waters) at 30 °C, using a mobile phase comprised of acetonitrile/methanol/50 mM ammonium acetate in 0.2% formic acid (95/2/3, v/v). Using a flow rate of 0.35 mL/min, the analysis time was 6.0 min. Mass spectrometric detection was by selected reactant monitoring (oxypurinol: m/z 150.8 → 108.0; internal standard: m/z 164.9 → 121.8) in negative electrospray ionization mode. Calibration curves were prepared in drug-free urine across the range 10–200 mg/L and fitted using quadratic regression with a weighting factor of 1/x (r2 > 0.997, n = 7). Quality control samples (20, 80, 150 and 300 mg/L) were used to determine intra-day (n = 5) and inter-day (n = 7) accuracy and imprecision. The inter-day accuracy and imprecision was 96.1–104% and <11.2%, respectively. Urinary oxypurinol samples were stable when subjected to 3 freeze–thaw cycles and when stored at room temperature for up to 6 h. Samples collected from 10 patients, not receiving allopurinol therapy, were screened and showed no significant interferences. The method was suitable for the quantification of oxypurinol in the urine of patients (n = 34) participating in a clinical trial to optimize therapy of gout with allopurinol. 相似文献