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41.
Wing bone stresses in free flying bats and the evolution of skeletal design for flight. 总被引:4,自引:0,他引:4
The primary mechanical functions of limb bones are to resist deformation, and hence provide stiff levers against which muscles can act, and to be sufficiently strong to prevent breaking under static or dynamic loads which arise from normal and accidental activities. If bones perform these functions with a minimum amount of material, the energetic costs associated with building, maintaining and transporting the skeleton will be minimized. Appropriate skeletal architecture for minimizing mass while maximizing strength depends on forces imposed on structural elements. In the evolutionary acquisition of flight in the bat lineage, the forelimb skeleton must have come to experience locomotor-forces that differed from those engendered by the terrestrial locomotion of non-flying bat relatives. Here we successfully measure in vivo strain on the wing bones of flying mammals. Our data demonstrate that torsion and shear are unique and crucial features of skeletal biomechanics during flight, and suggest that the evolution of skeletal design in bats and other flying vertebrates may be driven by the need to resist these loads. 相似文献
42.
Effect of exogenous ammonium on glutamine synthetase, glutamate synthase, and glutamate dehydrogenase in the root of rice seedling 总被引:1,自引:0,他引:1
Li Ze-song Zhang Chu-fu Lin Qing-hua Peng Jin Li Chang-jian He Guang-cun Peng Shao-bing John Bennett 《武汉大学学报:自然科学英文版》1999,4(3):358-362
Root biomass of rice seedlings was increased at lower concentration of exogenous NH
4
+
, but it was decreased at higher concentration of exogenous NH
4
+
. The level of free NH
4
+
in the roots was accumulated gradually with the increase of NH
4
+
concentration in the nutrient solution. The content of the soluble proteins was essentially constant at higher NH
4
+
. The activities of glutamine synthetase (GS), NADH-dependent glutamate synthase (NADH-GOGAT), and NADH-dependent glutamate
dehydrogenase (NADH-GDH) were risen with exogenous NH
4
+
concentration at the lower NH
4
+
concentration range. But the activities of GS and NADH-GOGAT were declined, and the level of NADH-GDH activity was kept constant
under higher NH
4
+
concentration. The GS/GDH ratio suggested that NH
4
+
was assimilated by GS-GOGAT cycle under lower NH
4
+
concentration, but NADH-GDH was more important for NH
4
+
assimilation and detoxifying NH
4
+
to the tissue cells at the higher NH
4
+
level. According to the growth and the activity changes of these ammonium-assimilating enzymes of rice seedling roots, 10.
0 μg/mL NH
4
+
-N in nutrient solution was more suitable to the rice growth.
Foundation item: Supported by the National Natural Science Foundation of China (No. 3987052), Natural Science Foundation of
Hubei Province and International Rice Research Institute, P.O. Box. 3217, 1271 Makati City, Philippines.
Biography: LI Ze-song(1968-), male, Graduate student. 相似文献
43.
Genomic sequence of the pathogenic and allergenic filamentous fungus Aspergillus fumigatus 总被引:1,自引:0,他引:1
Nierman WC Pain A Anderson MJ Wortman JR Kim HS Arroyo J Berriman M Abe K Archer DB Bermejo C Bennett J Bowyer P Chen D Collins M Coulsen R Davies R Dyer PS Farman M Fedorova N Fedorova N Feldblyum TV Fischer R Fosker N Fraser A García JL García MJ Goble A Goldman GH Gomi K Griffith-Jones S Gwilliam R Haas B Haas H Harris D Horiuchi H Huang J Humphray S Jiménez J Keller N Khouri H Kitamoto K Kobayashi T Konzack S Kulkarni R Kumagai T Lafon A Lafton A Latgé JP Li W Lord A Lu C Majoros WH May GS 《Nature》2005,438(7071):1151-1156
Aspergillus fumigatus is exceptional among microorganisms in being both a primary and opportunistic pathogen as well as a major allergen. Its conidia production is prolific, and so human respiratory tract exposure is almost constant. A. fumigatus is isolated from human habitats and vegetable compost heaps. In immunocompromised individuals, the incidence of invasive infection can be as high as 50% and the mortality rate is often about 50% (ref. 2). The interaction of A. fumigatus and other airborne fungi with the immune system is increasingly linked to severe asthma and sinusitis. Although the burden of invasive disease caused by A. fumigatus is substantial, the basic biology of the organism is mostly obscure. Here we show the complete 29.4-megabase genome sequence of the clinical isolate Af293, which consists of eight chromosomes containing 9,926 predicted genes. Microarray analysis revealed temperature-dependent expression of distinct sets of genes, as well as 700 A. fumigatus genes not present or significantly diverged in the closely related sexual species Neosartorya fischeri, many of which may have roles in the pathogenicity phenotype. The Af293 genome sequence provides an unparalleled resource for the future understanding of this remarkable fungus. 相似文献
44.
45.
Lim JE Jin O Bennett C Morgan K Wang F Trenor CC Fleming MD Andrews NC 《Nature genetics》2005,37(11):1270-1273
Hemoglobin deficit (hbd) mice carry a spontaneous mutation that impairs erythroid iron assimilation but does not cause other defects. Normal delivery of iron to developing erythroid precursors is highly dependent on the transferrin cycle. Through genetic mapping and complementation experiments, we show that the hbd mutation is an in-frame deletion of a conserved exon of the mouse gene Sec15l1, encoding one of two Sec15 proteins implicated in the mammalian exocyst complex. Sec15l1 is linked to the transferrin cycle through its interaction with Rab11, a GTPase involved in vesicular trafficking. We propose that inactivation of Sec15l1 alters recycling of transferrin cycle endosomes and increases the release of transferrin receptor exocytic vesicles. This in turn decreases erythroid iron uptake. Determining the molecular basis of the hbd phenotype provides new insight into the intricate mechanisms necessary for normal erythroid iron uptake and the function of a mammalian exocyst protein. 相似文献
46.
47.
N. Radoiu F. A. Zydeck R. R. Bennett 《Cellular and molecular life sciences : CMLS》1972,28(6):692-694
Résumé Les anti-anticorps pourraient avoir des applications theérapeutiques dans certains états allergiques, les maladies d'auto-immunisation et dans les greffes des tissues. Les auteurs montrent la possibilité de stimuler la formation des anti-anticorps specifiques contre les anticorps produits par des antigènes relativement simples comme l'albumine, le facteur Rh, le facteur rheumatoïde et la streptolysine 0 相似文献
48.
A pharmacological investigation of human isolated ileum 总被引:9,自引:0,他引:9
49.
Summary Labelled free choline injected into the peritoneum failed to enter the brain but preferentially entered the liver. Subsequently labelled phospholipid was found in the plasma with a concurrent increase in the brain. This labelled plasma injected by cardiac puncture caused a rapid incorporation of the choline labelled phospholipid into the brain. 相似文献
50.