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41.
GIORA HETH JOSEPHINE TODRANK NICOLAS BUSQUET CLAUDE BAUDOIN 《Biological journal of the Linnean Society. Linnean Society of London》2003,78(4):595-603
Previous research has demonstrated that closer genetic relatedness between individuals (from kin to across species) is associated with greater similarity in the qualities of their individual odours ('odour-genes covariance'). This predictable relationship between individual genotypes and individual odours could enable animals to assess their degree of genetic relatedness to other individuals by comparing the degree of similarity between another individual's odour and their own odour. In two-choice tests with odours of unfamiliar mice from different populations and species, subjects from two species of wild mice, Mus spicilegus and M. musculus , that had been raised in mixed litters of both species spent significantly more time investigating the ano-genital odour of the more genetically similar individual. This differential interest was not affected by common rearing with heterospecifics. These responses are consistent with a self-referencing mechanism enabling differential responses across a wide spectrum of genetic relatedness from kin through populations to heterospecifics. These assessments depend on the degree of similarity between the donor's and the subject's odours rather than on differences between them. Such a parsimonious mechanism may provide a basis for differential responses to conspecifics as opposed to heterospecifics that may function as a premating isolating mechanism. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78, 595–603. 相似文献
42.
A carbon-based model is described of the source-sink relationshipsof a stem bearing fruits in space and time and focusing on growthvariability along the branch. The novelty of the model comesfrom the aggregation of physiological processes taking intoaccount spatial aspects. The stem is represented as a set ofcompartments (metamers) connected to source (leafy shoots) andsink (fruits) compartments. Each leafy shoot forms one compartment.The fruit consists of three compartments involved in translocation(cytoplasm), structure (cell wall) and storage (vacuole). Physiologicalprocesses considered are photosynthesis, respiration of fruitsand leaves, translocation of assimilates and fruit growth. Assimilateproduction is regulated by sink strength. Carbon translocationbetween two compartments depends on the gradient of assimilateconcentration. The gradient induces carbon translocation fromthe most to the least concentrated compartment, except for thevacuole compartment into which translocation is possible whateverthe concentration gradient. Fruit growth, in terms of freshweight, results from the phloem water supplied to the fruitaccording to the concentration gradient between the fruit andthe stem. The model is calibrated for peach trees by comparingobserved and simulated fruit dry and fresh weights for a shootwith normal fruit load. The model simulates variability betweenpeach fruits and the effect of contrasting fruit loads. Accordingto this model, photosynthesis increases and assimilate concentrationsin leaves and phloem decrease with decreasing leaf:fruit ratioas reported in the literature. Simulated concentrations of assimilatesin the phloem range from 2 to 14%. Simulated concentration gradientsand specific mass transfer for peach trees range from 0.05 to0.17 g cm-3m-1and from 0 to 3 g cm-2h-1, respectively, and areof the same order of magnitude as those reported for variousother tree species. The model is used to analyse the effectof fruit position relative to the leaves. Copyright 1999 Annalsof Botany Company Peach tree, Prunus persica (L.) Batsch, model, carbohydrates, translocation, source-sink, fruit. 相似文献
43.
44.
DNA staining with Hoechst 33258 allows us to visualize and to characterize amitotic division of Acanthamoeba castellanii in which the cell nucleus divides without DNA condensation and regular segregation of chromosomes. Amitosis involves several programmed and coordinated steps that exclude accidental cutting of the cell nucleus. 相似文献
45.
Reversal of eutrophication in Lake Geneva: evidence from the oligochaete communities 总被引:3,自引:0,他引:3
1. In Lake Geneva (Switzerland), total phosphorus concentrations have decreased from 90 mg m?3 in 1979 to 55 mg m?3 in 1990. 2. To assess the effects of this improvement, tubificid and lumbriculid communities were sampled in 1982 and in 1991 in the same areas, at a depth of 40 m. 3. Abundance of mesotrophic species (mostly Potamothrix vejdovskyi) and of eutrophic species (mostly Potamothrix hammoniensis) was lower in 1991 than in 1982; in contrast, oligotrophic species (mostly Peloscolex velutinus) were more abundant in 1991 than in 1982. 4. The changes recorded in 1991 were the same as those associated with a decrease of organic sedimentation. 5. Mean relative abundance of oligotrophic species increased from 17% in 1982 to 41% in 1991. According to these values, Lake Geneva was mesoeutrophic in 1982, but mesotrophic in 1991. 相似文献
46.
J. M. BOURRE C. CASSAGNE S. LARROUQUERE-REGNIER D. DARRIET 《Journal of neurochemistry》1977,29(4):645-648
Alkanes, a new class of neurolipid, were found in mouse brain, the level being reduced in the Quaking mutant. These hydrocarbons are concentrated in myelin; minor amounts being found in microsomes, mitochondria and synaptosomes. The average recovery is 7.1 μg/mg in normal myelin, 2.2 in the Quaking myelin. The distribution pattern of these alkanes was determined by gas liquid chromatography and was found to differ in normal and Quaking myelin; the hydrocarbons consist mainly of n-alkanes ranging from C21 to C32 with even and odd aliphatic chains. 相似文献
47.
ANTHONY M. HEAPE JEAN-JACQUES BESSOULE FRANÇOISE BOIRON-SARGUEIL CLAUDE CASSAGNE 《Neurochemistry international》1996,29(6):607-622
In vivo glycerolipid metabolism was studied in sciatic nerves of normal and Trembler mice. The results showed that two kinetically independent pathways were implicated in the labeling of diacylglycerophospholipids from [3H]palmitate: the Kennedy pathway and a ‘direct acylation’ pathway. In normal nerves, 45% of the glycerophospholipids were labeled, with a rate constant k3 = 3.9 × 10−3 min−1, from phosphatidic acid and diacylglycerol intermediates, themselves formed with a rate constant of k1 = 0.24 min−1 from a free 3H-fatty acid pool, FFA1, that represents 45% of the total injected label. The remaining 55% of the glycerophospholipids were labeled from a kinetically distinct free 3H-fatty acid pool, FFA2, with a rate constant of k4 = 9.8 × 10−2, via a process that does not implicate a detectably labeled metabolic intermediate (‘direct acylation’). Glycerophospholipid labeling via the Kennedy pathway in the Trembler mouse sciatic nerves was reduced to 75% of the normal level, while labeling via the ‘direct acylation’ pathway was increased 1.4-fold. The values of the rate constants for free 3H-fatty acid utilisation (k1 and k4) were both increased about 2.5-fold, while that of glycerophospholipid formation from diacylglycerol (k3) was close to normal. Copyright © 1996 Elsevier Science Ltd 相似文献
48.
ETIENNE-EMILE BAULIEU SABINE SCH
RDERET-SLATKINE CLAUDE LE GOASCOGNE JEAN-PAUL BLONDEAU 《Development, growth & differentiation》1985,27(3):223-231
There is a membrane progesterone receptor in Xenopus laevis oocytes that undergo meiosis under steroid exposure. Early responses include a decrease of leucine uptake, a decrease of adenylate cyclase and alkaline phosphatase activities, and a decrease of the phosphorylation of a specific p48 protein in the membrane. These results are compatible with a decrease of membrane fluidity brought about by the hormonal message. However the above-cited effects as well as the Ca2+-changes are not yet enough well understood to be able to precisely delineate their role in meiosis reinitiation. 相似文献
49.
CLAUDINE MONTGELARD † YVES BENYAMIN† ‡ CLAUDE ROUSTAN‡ LOUIS THALER 《Biological journal of the Linnean Society. Linnean Society of London》1990,41(1-3):163-169
An immunological test that can be made on living animals is developed to identify M. m. musculus mice from the two other short-tailed mice ( M. spicilegus and M. spretoides ) occurring in Eastern Europe. This test uses fractionated albumin antiserum as an immunological marker and is performed using dot-blot immunoassay. One hundred and twelve animals belonging to the three species and originating from wild-caught mice and from laboratory strains were tested. All the M. m. musculus mice were correctly identified with this test. Owing to its simplicity and reliability, this test will be very useful in field surveys, particularly in the zone of sympatry between M. m. musculus and M. spicilegus . 相似文献
50.
The effect of in vitro irradiations on ihe pelletability of peroxitlase activity was tested in extracts prepared from leaves of light-grown spinach (Spinacia oleracea). It appeared that far red light increased the pelletable activity and that red light reversed this effect. This phytochrome-mediated effect occurred in a particulate fraction which banded at 39% (w/w) sucrose on an isopycnic density gradient. 相似文献