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31.
The rates of sulphate transport into intact and excised rootsof soybean (Glycine max L.) were not significantly differentin the first hour and were maximal at pH 7. However, intactroots accumulated four times as much sulphate as excised rootsin 24 h, because of a marked reduction in the rate of transportby excised roots. The continued high rates of transport intointact roots were observed in plants kept in the light, andobserved in darkened plants growing in 1 per cent sucrose. Similarly,sulphate accumulation by excised roots was stimulated 2-foldby 1 per cent sucrose. The characteristics of sulphate accumulation by roots were notuseful in predicting sulphate translocation to the leaves. Transportto the leaves was maximal at pH 23, was almost totallylight-dependent and was not enhanced by growing plants in sucrose. Sulphate transport, Glycine max L., soybean, excised roots 相似文献
32.
THE QUANTITATIVE STUDY OF MYCORRHIZAL INFECTION 总被引:10,自引:9,他引:1
33.
The effect of changes in the environment on lipid metabolismhas been studied in the brown alga, Fucus serratus L. Lightstimulated the incorporation of radioactivity from /{I4C/}acetateinto oleic and, especially, into linoleic acid. The same effectwas caused by lowering the incubation temperature from 15 °Cto 4 °C. Incubations in the presence of Cd + +, Pb + + orZn+ + had no effect on the total uptake of /{14C/}acetate intothe frond tip samples, but lowered the labelling of total lipidsrelative to aqueous-soluble components. However, pre-exposureof the algae to heavy metal cations caused changes in the uptakeof radioactivity but had less effect on the relative labellingof lipids than incubations in the presence of heavy metal cations.Algae collected from sites where the dissolved levels of heavymetals were elevated, showed a decrease in the relative labellingof lipids from /{14C/}acetate. Concentrations of Cd+ +, Pb++ or Zn+ + at 10 x levels found at the collection site had littleeffect on the pattern of fatty acids made by Fucus serratus. Key words: Lipid metabolism, Fucus serratus L., Environmental changes 相似文献
34.
A monoclonal antibody to ochratoxin A 总被引:1,自引:1,他引:0
The production of patulin by P. expansum Link ex Gray growing in apple juice was determined over a range of pH. Patulin was found to be produced in large quantities over a narrow range of pH from 3-2 to 3–8. The biomass produced increased with increasing pH. The changes in pH due to growth of the organism were found to be small. 相似文献
35.
36.
A late Wenlock flora from Co. Tipperary, Ireland 总被引:1,自引:0,他引:1
D. EDWARDS F.L.S. J. FEEHAN D. G. SMITH 《Botanical journal of the Linnean Society. Linnean Society of London》1983,86(1-2):19-36
An assemblage of macroplants preserved as highly coalified compressions which lack anatomy is described from a Wenlock locality in County Tipperary, Ireland. Most of the fertile specimens are assigned to Cooksonia Lang. The taxonomic status of this genus is discussed. Some poorly preserved palynomorphs, including miospores, acritarchs, chitinozoans and a variety of tubes, have been isolated from associated sediments, but the age of the flora is based on graptolites. Sedimentological and palaeontological studies of the region are summarized. They provide little direct evidence for the habitats of the plants which are considered to have been terrestrial. The relevance of this flora to the current debate on the colonization of the land is evaluated and it is concluded that these plants provide the earliest record of erect fertile land plants of possible pteridophyte affinity. 相似文献
37.
During the first month after germination peanut and sunflowerseedlings exhibit a significant shift in the 13C/12C ratiosof respired CO2 indicating thatcarbohydrate gives way to lipidas the respiratory substrate. Other species (castor bean, corn,pea,radish, squash and wheat) show no change in the 13C/12C ratio (Received March 9, 1971; ) 相似文献
38.
The transport of abscisic acid in cotyledonary petiole sectionsof cotton seedlings was investigated using (2-14C)-ABA in adonor-receiver system. Using the intercept technique, a transportvelocity of 22.4 mm/hr was determined. This velocity was foundto be independent of the length of the petiole or of the concentrationof ABA applied. In a 24-hr period 70% of the applied ABA movedthrough the tissue sections. No polarity was found in any ofthe studies. The capacity of the transport system decreased with increasingage of the tissue and with increasing time of pre-exposure toABA. When metabolism of the tissue was restricted by cold temperature,low-O2 tension or DNP treatment, transport was inhibited 80to 98%.The distribution of ABA in the petiole during transportwas also investigated. The results are discussed in relationto the well-studied transport of IAA and in relation to thephysiologicalrole of ABA.
1 Present address: Stanford Research Institute-Irvine, 19722Jamboree Blvd., Irvine, Calif. 92664, U.S.A. (Received November 30, 1970; ) 相似文献
39.
IN mammals, with the exception of artiodactyls and cetaceans, it is generally accepted that intrinsic cardiac ganglion cells are confined distally by the atrioventricular groove1. This is interpreted as indicating that vagal influence is limited to the atrial and specialized tissues and this concept is supported by much physiological evidence. It has been suggested that, in dogs, the vagi exert a direct negative inotropic effect on the ventricles2, although Furnival et al.3 found that this effect was relatively insignificant. Morphologists have, however, reported ventricular ganglion cells in primates4–6. We offer here morphological evidence for the existence of ventricular ganglion cells in the cat. 相似文献
40.
Light Intensity and Substrate Availability in Relation to Tracheid Development in Picea sitchensis 总被引:1,自引:0,他引:1
Assimilation and growth of Picea sitchensis seedlings maintainedat three light intensities were examined in relation to previously-reporteddata on tracheid development in this species. Increases in photosynthetic efficiency with decreased lightlevel failed to compensate completely for reduced total amountsof incident radiation as judged from assimilate distributionpattern and growth rate. Incorporation of assimilate into reservesand new growth declined with decreased light level, while theextent of turnover materials generally increased. Most treatment differences in relative dry weight distributionappeared to result from a combination of differences in growthrate and changes in growth pattern. The proportion of dry weightin branches and roots increased with increased light intensitywhile that in stems and the hypocotyl decreased At the two highest light levels tested, both absolute stem growthrate and total wall accumulation appeared to be independentof substrate availability. This situation contrasts with thatobserved in older material and it is suggested that the initialindependence reflects the temporary existence of a high ratioof functional foliage to stem and cambial material during thefirst year of growth. Since tracheid diameter showed a consistent, positive relationshipwith assimilate status, it is suggested that substrate levelcan exert an important modifying influence on cell expansion. 相似文献