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241.
For many biological systems, the behavior of interest is contained in the evolution of transients rather than in the stability
of equilibria. These include systems in which perturbations and interruptions occur on a time scale much shorter than the
equilibration time, and those in which any final equilibrium is sensitive to initial conditions. In this article, we examine
a model of fungal root disease in a crop involving primary and secondary infection mechanisms. This system is subject to regular
interruptions in the form of harvesting and sowing. Using an asymptotic approach in which certain parameter values are assumed
to be small, the model can be broken down into a set of simpler subsystems respresenting recognizable biological mechanisms.
These linear models can be solved to give closed-form analytical solutions for transient evolution. From this information,
it is possible to construct an annual map of disease severity in the crop, and determine the parameter values under which
the infection will bulk up or fade out. 相似文献
242.
243.
S B Gilligan I B Borecki S Mathew K C Malhotra D C Rao 《American journal of physical anthropology》1985,68(3):409-416
Palmar pattern ridge counts were subjected to segregation analysis in an attempt to identify possible major gene effects on these dermatoglyphic traits. The phenotypes considered were total palmar pattern ridge count, and ridge counts for the right interdigital III and IV and left interdigital IV individual palmar areas (sample sizes were too small for the other palmar areas). Evidence of familial resemblance was found for all of the phenotypes studied, and initial evidence for a major effect was found for all but the right palm interdigital III ridge count. However, this initial evidence could be attributed to nongenetic effects in each case, including skewness in the trait distribution. Tests for agreement with Mendelian transmission frequencies were found to be very useful in discriminating between a non-Mendelian major effect and a major gene. We concluded against a major gene effect for any of these traits, and multifactorial inheritance remains a plausible alternative explanation for the familial resemblance. 相似文献
244.
A fluorometric assay for peptidyl alpha-amidation activity using high-performance liquid chromatography 总被引:1,自引:0,他引:1
B N Jones P P Tamburini A P Consalvo S D Young S J Lovato J P Gilligan A Y Jeng L P Wennogle 《Analytical biochemistry》1988,168(2):272-279
A rapid and sensitive method for the determination of peptidyl alpha-amidation activity has been developed and is based on reverse-phase high-performance liquid chromatographic separation and fluorometric detection. A dansylated tripeptide, N-dansyl-Tyr-Val-Gly-OH, is used as the substrate in the assay and the amount of alpha-amidation activity is determined by quantitating the extent of its conversion to product, N-dansyl-Tyr-Val-NH2. Both product and substrate can be detected in a single assay in quantities as low as 5 fmol by isocratic elution using C-18 reverse-phase columns. The method yields highly reproducible results and requires less than 3 min per sample for separation and quantitation. The assay procedure is applicable to the screening of a large number of samples under different pH conditions and is readily adaptable for use in a variety of studies. For example, the procedure is ideal for detecting alpha-amidation activity in various tissues, monitoring activity at the different stages during purification of a particular alpha-amidation enzyme, determining kinetic parameters of the purified enzyme, and identifying both competitive and noncompetitive inhibitors. 相似文献
245.
采用非洲爪蟾卵提取物非细胞体系,以外源Lambda DNA诱导细胞核的体外组装,以此实验模式为基础,研究了细胞核体外组装过程中核纤层的组装,结果表明核纤层蛋白参与细胞核的体外组装过程,核内骨架的组装与核纤层的组装在时间上是有序的,核内骨架的组装可能为核纤层的装配提供了先决条件.在非洲爪蟾卵提取物非细胞体系中加入抗核纤层蛋白抗体,抑制核纤层的正常装配过程,核膜组装发生异常.结果提示核纤层的组装与核膜的组装是密切相关的. 相似文献
246.
Emmanuel T. Rakitzis Paul J. Gilligan Joseph F. Hoffman 《The Journal of membrane biology》1978,41(2):101-115
Summary A kinetic analysis of anion self-exchange in human red blood cells, in the presence of an irreversible inhibitor, is presented and applied to the study of the inactivation of sulfate transport by three isothiocyanates: 3-isothiocyano-1,5-naphthalenedisulfonic acid, disodium salt (INDS), 1-isothiocyano-4-naphthalene sulfonic acid, sodium salt, monohydrate (INS), and 1-isothiocyano-4-benzenesulfonic acid, sodium salt, monohydrate (IBS). The time dependence of the inhibition of sulfate transport by the isothiocyanates used could be described by a single exponential and could be shown to contain a reversible and an irreversible component. In each case a portion of sulfate efflux was found to be resistant to inactivation. The residual portion of the sulfate efflux varied with inhibition: 4% for INS, 16% for INDS, and 34% for IBS. INS showed the largest reversible inhibitory effect (12% of the flux remaining at 0.2mm inhibitor concentration), while INDS showed the weakest effect (92% of the flux remaining at 0.3mm inhibitor concentration). IBS had the highest rate of inactivation while INDS had the lowest. The kinetic analysis further suggests that all three isothiocyanates bind reversibly to an inhibitory site on the membrane before they bind covalently, and therefore irreversibly, to the same site on the membrane. The equilibrium constant for the dissociation of the reversibly-bound complex,K
i, and the rate of irreversible inactivation after all membrane sites are reversibly bound,k
max, have been computed for all three inhibitors: INDS (K
i=420m,k
max=5.04 hr–1), INS (K
i=148 m,k
max=6.48 hr–1), and IBS (K
i=208 m,k
max=8.11 hr–1). 相似文献
247.
248.
Maslov LN Lishmanov IuB Bogomaz SA Gilligan P Tam SW 《Rossi?skii fiziologicheski? zhurnal imeni I.M. Sechenova / Rossi?skaia akademiia nauk》1999,85(11):1396-1408
Pre-treatment of the sigma-receptor with the sigma-receptor agonist (+)-SKF 10.047 improved the reperfusion recovery of cardiac pump function. The sigma-receptor activation, among other effects, prevented the reperfusion contracture, increased pressure in the left ventricle, and improved survival of cardiomyocytes after ischemia/reperfusion. Pre-treatment with the sigma-receptor antagonist DuP 734 augmented the reperfusion systolic dysfunction of the myocardium and prevented postischemic contractures and cardiac cell lesions. Activation of the cardiac sigma-receptor seems to prompt an augmentation of tolerance to the reperfusion damage. 相似文献
249.
250.
Thomas Gilligan Hideaki Yamada Toru Nagasawa 《Applied microbiology and biotechnology》1993,39(6):720-725
A new soil isolate, tentatively identified as Rhodococcus equi TG328, was found to be effective in the production of S-(+)-2-phenylpropionic acid from (R,S)-2-phenylpropionitrile. The conversion is catalysed by two enzymes. First, a nitrile hydratase converts the (R,S)-nitrile to (R,S)-2-phenylpropionamide. Second, a stereoselective amidase converts the S-(+)-amide to S-(+)-2-phenylpropionic acid. Conditions for optimal enzyme production and accumulation of S-(+)-2-phenylpropionic acid by resting cells were studied. The reaction of resting cells for 30 h at 10° C with (R,S)-2-phenylpropionitrile resulted in the production of 100 g of S-(+)-2-phenylpropionic acid per litre of reaction mixture. The enantiometric excess of the purified S-(+)-2-phenylpropionic acid was 99.4%. The amount of S-(+)-2-phenylpropionic acid accumulated was enhanced by lower reaction temperatures. In addition, unreacted R-(–)-2-phenylpropionamide with 99.0% enantiometric excess was isolated.
Correspondence to: T. Nagasawa 相似文献