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Based on experiments on agarose gels and tissue, a procedure has been developed which greatly improves the sensitivity and the specifity of the Kossa method for demonstrating calcium in tissue. Tissue calcium is immobilized by acetonic oxalic acid, which simultaneously removes the other sorts of anions capable of precipitating silver ions (e.g. phosphate, carbonate). The resulting submicroscopic grains of calcium oxalate are converted first into silver oxalate then into metallic silver by a treatment with silver nitrate followed by an ultra-violet irradiation (Kossa reaction). These submicroscopic metallic silver grains are enlarged up to microscopic visibility by means of physical development, which makes the staining highly sensitive. Co-staining of the argyrophil sites in the tissue is totally suppressed by various tricks, which render the silver staining selective for calcium. 相似文献
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Wolff A. H.; Coleshaw S. R.; Newstead C. G.; Keatinge W. R. 《Journal of applied physiology》1985,58(3):770-777
Flow of water under foam neoprene wet suits could halve insulation that the suits provided, even at rest in cold water. On the trunk conductance of this flow was approximately 6.6 at rest and 11.4 W . m-2 . C-1 exercising; on the limbs, it was only 3.4 at rest and 5.8 W . m-2 . degrees C-1 exercising; but during vasoconstriction in the cold, skin temperatures on distal parts of limbs were lower than were those of the trunk, allowing adequate metabolic responses. In warm water, minor postural changes and movement made flow under suits much higher, approximately 60 on trunk and 30 W . m-2 . degrees C-1 on limbs, both at rest and at work. These changes in flow allowed for a wide range of water temperatures at which people could stabilize body temperature in any given suit, neither overheating when exercising nor cooling below 35 degrees C when still. Even thin people with 4- or 7- mm suits covering the whole body could stabilize their body temperatures in water near 10 degrees C in spite of cold vasodilatation. Equations to predict limits of water temperature for stability with various suits and fat thicknesses are given. 相似文献
4.
Tubulin subunit carboxyl termini determine polymerization efficiency 总被引:21,自引:0,他引:21
Cleavage of tubulin by subtilisin removes a small (Mr less than 2000) fragment from the C-terminal end of both alpha and beta subunits. The resulting protein is much reduced in negative charge. The cleaved, less acidic protein retains its competence to polymerize in a GTP-dependent and cold-, GDP-, and podophyllotoxin-sensitive manner and assembles into sheets or bundles of twisted filaments. The critical concentration for polymerization of the cleaved protein is about 50-fold lower than that for intact tubulin. It is proposed that the C termini of the subunits normally impede polymerization. 相似文献
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Management of the Wadden Sea 总被引:1,自引:0,他引:1
The Wadden Sea situated along the North Sea coasts of Denmark, the Federal Republic of Germany and The Netherlands represents
one of the world's largest bar-built type of estuaries. The area is a typical sedimentation and mineralization basin, with
a large influx of organic matter from the adjoining North Sea, consequently a delicate oxygen balance and a rich benthic macrofauna,
poor in species, which serves as food for juveniles of some commercially important North Sea fishes and for large numbers
of migrating and wintering waders and waterfowl. Past and present activities of the human society in the area include fisheries
(mainly for shrimp and mussels, semi-culture), shipping, land reclamation, recreation, dredging for sand and shells, and waste
discharge from industries and human communities. Until the present these activities, although sometimes conflicting, did not
fundamentally affect the area and its biota (pollution excluded), but future claims, including the construction of large deep-sea
harbours, drilling for natural gas and oil, large-scale land reclamation and increased industrialization etc., might gradually
induce degradation. For instance, area reduction by continued land reclamation could lead to irreversible losses of specific
biotopes (e. g. salt-marshes, mud-flats), which could affect the size of bird and fish populations in a much wider region.
Increased pollution, which has already inflicted damage on bird and seal populations, could reduce the fauna and hence the
value of the area as a natural sanctuary. In the event of a proposal for a new human activity in the area, the present standing
practice in the countries concerned requires an evaluation of its safety and economic aspects and its environmental impact.
However, the various plans are considered separately and there is a general need for integrated management of the area. 相似文献
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W. J. Wolff 《Hydrobiologia》1973,42(4):381-392
The distribution of Asellus aquaticus and Proasellus meridianus in the southwestern part of the Netherlands is described. Differences cannot be ascribed to different salinity tolerances, but a different pollution tolerance seems probable. 相似文献
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