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361.
Pollination precision and efficiency have been deemed to be important driving forces in floral evolution. Herkogamy reduction is a main mechanism to increase pollination precision. Secondary pollen presentation (SPP), by which pollen is presented on other floral organs especially pistils, has been widely accepted as a special mechanism to increase pollen transfer precision through spatial reduction of the anther–stigma distance, that is, minimized herkogamy. This overlooks a potential driving force, that is expanding the pollination niche through converting pollen thieves and nectar robbers into effective pollinators. We selected two species as study models with typical pistillate SPP, Pavetta hongkongensis Bremek. (Rubiaceae) and Scaevola taccada (Gaertn.) Roxb. (Goodeniaceae). In both species, two distinct pollinator functional groups were recognized. Short-tongued bees and flies fed on pollen on stigmas but also stole pollen from anthers and robbed nectar, whereas long-tongued hawkmoths and butterflies only collected nectar. Emasculation had no influence on long-tongued pollinators, but significantly decreased the visitation frequency of short-tongued visitors and fruit set, compared to intact flowers, demonstrating short-tongued visitors did not effectively pollinate and acted merely as pollen thieves or nectar robbers when SPP was absent. Data from the two plant species clearly indicated pistillate SPP has additional adaptive advantages of converting ineffective visitors into pollinators and consequently widening the pollination niche, which could help plants overcome environmental stochasticity. Our results suggest that multiple selective forces drive the evolution of SPP and the minimization of herkogamy. 相似文献
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Cornelius R. Pawlak Carles Sanchis-Segura Dian Soewarto Sibylle Wagner Martin Hrabé de Angelis Rainer Spanagel 《Mammalian genome》2008,19(2):77-84
The aim of this study was the application of a phenotype-driven N-ethyl-N-nitrosourea (ENU) mutagenesis screen in mice for the identification of dominant mutations involved in the regulation and
modulation of alcohol-drinking behavior. The chemical mutagen ENU was utilized in the generation of 131 male ENU-mutant C57BL/6J
mice (G0). These ENU-treated mice were paired with wild-type C57BL/6J mice to generate G1 and subsequent generations. In total,
3327 mice were generated. Starting with G1, mice were screened for voluntary oral self-administration of 10% (v/v) alcohol
vs. water in a two-bottle paradigm. From these mice, after a total period of 5 weeks of drinking, 43 mutants fulfilled the
criteria of an “alcohol phenotype,” that is, high or low ethanol intake. They were then selected for breeding and tested in
a “confirmation cross” (G2–G4) for inheritance. Although we did not establish stable high or low drinking lines, several results
were obtained in the context of alcohol consumption. First, female mice drank more alcohol than their male counterparts. Second,
the former demonstrated greater infertility. Third, all animals displayed relatively stable alcohol intake, although significantly
different in two different laboratories. Finally, seasonal and monthly variability was observed, with the highest alcohol
consumption occurring in spring and the lowest in autumn. In conclusion, it seems difficult to identify dominant mutations
involved in the modulation or regulation of voluntary alcohol consumption via a phenotype-driven ENU mutagenesis screen. In
accordance with the findings from knockout studies, we suggest that mainly recessive mutations contribute to an alcohol-drinking
or alcohol-avoiding phenotype. 相似文献
365.
Participatory Measurement, Reporting and Verification (PMRV), in the context of reducing emissions from deforestation and forest degradation with its co-benefits (REDD+) requires sustained monitoring and reporting by community members. This requirement appears challenging and has yet to be achieved. Other successful, long established, community self-monitoring and reporting systems may provide valuable lessons. The Indonesian integrated village healthcare program (Posyandu) was initiated in the 1980s and still provides effective and successful participatory measurement and reporting of child health status across the diverse, and often remote, communities of Indonesia. Posyandu activities focus on the growth and development of children under the age of five by recording their height and weight and reporting these monthly to the Ministry of Health. Here we focus on the local Posyandu personnel (kaders) and their motivations and incentives for contributing. While Posyandu and REDD+ measurement and reporting activities differ, there are sufficient commonalities to draw useful lessons. We find that the Posyandu kaders are motivated by their interests in health care, by their belief that it benefits the community, and by encouragement by local leaders. Recognition from the community, status within the system, training opportunities, competition among communities, and small payments provide incentives to sustain participation. We examine these lessons in the context of REDD+. 相似文献