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101.
Somatic Embryogenesis and Plant Regeneration from Cultured Leaf Explants of Zea mays 总被引:4,自引:0,他引:4
Young leaf segments of Zea mays L. seedlings were cultured onMurashige and Skoog's basal nutrient medium supplemented with2 mg l1 2, 4-D and sub-cultured on medium containing8 mg l1 2,4-D. Two types of callus tissues appearedembryogenicand non-embryogenic. The embryogenic callus tissue producednumerous somatic embryos which on transfer to media containinglow amounts of 2,4-D or ABA produced plantlets. Callus tissuesexhibited embryogenic potential for more than 1 year. Zea mays L. cv. Ageti-76, Zea mays L. cv. N-L-D-Comp., maize, leaf, callus, somatic embryogenesis, regeneration 相似文献
102.
Cold Pseudechis porphyriacus aid heating by basking, flattening and tilting. When body temperatures are higher, thermoregulation is achieved by shuttling between sun and shade. A warm snake in a cooling environment frequently coils.
The major factors associated with rate of temperature change in the body core were (1) horizontal gradient between body and neck, (2) posture and (3) vertical gradients from body core to body surface.
The role of behavioral, physiological and physical factors in thermoregulation are discussed. 相似文献
The major factors associated with rate of temperature change in the body core were (1) horizontal gradient between body and neck, (2) posture and (3) vertical gradients from body core to body surface.
The role of behavioral, physiological and physical factors in thermoregulation are discussed. 相似文献
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104.
SYNOPSIS. A new coccidium Sivatoshella lonchurae n. gen., n. sp. (Coccidia, Eimerüdae) is described from the gut of the passeriform birds Lonchura malabarica (Linn.) and L. punctulata (Linn.). Endogenous stages of the parasite conform to those of the family Eimerüdae. Oocysts are spherical, 36–38 μ (avg. 37.5 μ) in diameter. Wall 3.6 ä thick, 4-layered; outermost layer thin transparent and colorless; next, slightly broader and light green; 3rd, thinner and light yellow; innermost dark black. Oocyst residuum absent. Micropyle absent. Sporocysts 28–29 μ long and 18 μ wide. They are 2 broad pear-shaped bodies with Steida body and a prominent substeidal body at the narrow pole. Sporocyst residuum present as minute refractile globules embedded in a dark matrix. Sporozoites broad, comma-shaped, with one large vacuole at the broad pole and nucleus at the center of the body. Sixteen sporozoites in each sporocyst, arranged at the periphery of the residual mass. Sporulation time : 24–48 hours at 31 C. Habitat: duodenum and small intestine of Lonchura malabarica (Linn.) and L. punctulata (Linn.). Locality: Calcutta, W. Bengal, India. 相似文献
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Abstract: Wetlands in the Playa Lakes Region (PLR) provide important habitats for wintering waterfowl, cranes, and both migrant and breeding shorebirds. Playa Lakes Region wetlands experience naturally fluctuating hydroperiods but are exposed to anthropogenic stresses, which are exacerbated during summer and may influence PLR wetland occupancy and selection by breeding shorebirds. We examined wetland-scale habitat use and nest-site selection of the 4 dominant shorebirds (American avocets [Recurvirostra americana], black-necked stilts [Himantopus mexicanus], killdeer [Charadrius vociferus], snowy plovers [C. alexandrinus]) nesting in playas, saline lakes, and in both created and riparian wetlands in the PLR of Texas, USA. All 4 species nested in saline lakes. Only avocets and killdeer nested in playas, and snowy plovers nested in riparian wetlands. No nests were found in created wetlands. Wetland habitat changed (P < 0.001) during the breeding season, while water habitats generally decreased. Used (i.e., shorebirds found nesting) wetlands had more (P < 0.05) mudflats than non-used (i.e., shorebirds not found nesting) wetlands, which had more (P < 0.05) dry habitats. Used and non-used wetlands had similar (P > 0.05) amounts of water habitats. Nests were located close to vegetation on bare dry ground and dry ground with vegetation. Because water is ephemeral in PLR wetlands, shorebirds must select—in a somewhat predictive manner upon arrival—wetlands with suitable nest-site and brood-rearing habitat. Although surface water is necessary for nesting, its presence is not adequate for delineating suitable PLR wetland habitat for breeding shorebirds. Our findings that created wetlands cannot compensate for regional wetland losses in habitat or function highlights the need for conservation of natural PLR wetlands 相似文献
107.
The major Indian carps namely rohu (Labeo rohita), catla (Catla catla), mrigal (Cirrhinus mrigala) and calbasu (Labeo calbasu) are important freshwater species of the Indian subcontinent constituting over 65% of the fish produce. In the present study, isolation of 12 microsatellite loci from rohu has been reported. Cross‐species amplification in related carps and their implication in population genetic studies as well as selective breeding program were discussed. 相似文献
108.
RYAN T. JONES ANDREW P. MARTIN ADAM J. MITCHELL SHARON K. COLLINGE CHRIS RAY 《Molecular ecology resources》2005,5(1):71-73
We report the development of 14 polymorphic microsatellite markers for the black‐tailed prairie dog, Cynomys ludovicianus. The number of alleles per locus ranges from three to 11, and the observed heterozygosity ranges from 0.37500 to 1.0000. These markers will benefit studies of landscape effects on prairie dog migration, disease dynamics, and conservation efforts. 相似文献
109.
Seeds of rice variety Chinsurah Boro were treatedwith two concentrations of indoleacetic acid (IAA) and maleichydrazide (MH), 0.1 mg. per litre and 0.01 mg. per litre, duringthe first 7 days of germination, and the resulting changes innitrogen metabolism of both endosperm and embryo were determined.The seedling growth at different times during the treatmentwas recorded. Uptake of water by the embryo increased up to 72 hours, butthereafter the percentage water content fell, owing to large-scaletranslocation of dry matter to it. The endosperm showed increasingwater content for 5 days. There are two marked stages of nitrogen metabolism of the seedduring germination. During the first 72 hours hydrolysis ofprotein in the endosperm and translocation of soluble nitrogento the embryo are the predominant features. Thereafter the embryoactively synthesizes protein from the products of translocation. IAA and MH affected the seedling growth similarly. Initiallythere was a small retardation of leaf growth, but at later periodsrecovery took place. Root growth was more adversely affectedthan shoot growth, the effect also persisting longer. Thesechanges in growth were reflected in the nitrogen metabolismof the seedlings. For the first few days IAA and MH retardedthe supply of soluble nitrogen from the endosperm to the embryo,consequently there was less soluble nitrogen in the embryo thoughprotein synthesis there was affected only slightly. The differencein soluble nitrogen between the treated and untreated embryospersisted throughout the seven days. An attempt is made to explainthis on the basis that primarily IAA and MH retard the enzymaticactivity responsible for the hydrolysis of protein in the endosperm. 相似文献
110.