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451.
E. E. Stüeken R. E. Anderson J. S. Bowman W. J. Brazelton J. Colangelo‐Lillis A. D. Goldman S. M. Som J. A. Baross 《Geobiology》2013,11(2):101-126
Many decades of experimental and theoretical research on the origin of life have yielded important discoveries regarding the chemical and physical conditions under which organic compounds can be synthesized and polymerized. However, such conditions often seem mutually exclusive, because they are rarely encountered in a single environmental setting. As such, no convincing models explain how living cells formed from abiotic constituents. Here, we propose a new approach that considers the origin of life within the global context of the Hadean Earth. We review previous ideas and synthesize them in four central hypotheses: (i) Multiple microenvironments contributed to the building blocks of life, and these niches were not necessarily inhabitable by the first organisms; (ii) Mineral catalysts were the backbone of prebiotic reaction networks that led to modern metabolism; (iii) Multiple local and global transport processes were essential for linking reactions occurring in separate locations; (iv) Global diversity and local selection of reactants and products provided mechanisms for the generation of most of the diverse building blocks necessary for life. We conclude that no single environmental setting can offer enough chemical and physical diversity for life to originate. Instead, any plausible model for the origin of life must acknowledge the geological complexity and diversity of the Hadean Earth. Future research may therefore benefit from identifying further linkages between organic precursors, minerals, and fluids in various environmental contexts. 相似文献
452.
Salinomycin inhibits epigenetic modulator EZH2 to enhance death receptors in colon cancer stem cells
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454.
Linear programming methods, indicators of nutritional adequacy from the Indian Council of Medical Research and household expenditure survey data from the National Sample Survey Organization were used to construct poverty lines for India. Poverty ratios were calculated for 1993--1994 and 1999--2000 on the basis of nutritional adequacy poverty lines and compared to official estimates of poverty based on energy requirements. Nutritional adequacy poverty lines are higher than official poverty lines, particularly in rural areas. The application of nutritional adequacy poverty lines points to greater rural-urban poverty differences than in official estimates. Declines in rural poverty during the 1990s were also slower under the nutritional adequacy definition, especially in south India. There is a greater degree of rural-urban and regional bias in nutritional adequacy poverty reduction than suggested by official data. Inter-state variations in changes in nutritional poverty and official poverty in the 1990s are largely explained by differences in assumptions on overall price movements. However, relative price movements in food items also played a role, particularly the slow increase in prices of cereals and edible oils in comparison to the prices of pulses, and in some southern states, compared to milk and vegetable prices as well. 相似文献
455.
Dixit Neeraj Kumar Kumar Anup 《International journal of peptide research and therapeutics》2021,27(2):1385-1396
International Journal of Peptide Research and Therapeutics - Dengue is an infectious disease caused by one of the four serotypes of the dengue virus. It is a mosquito borne disease and the female... 相似文献
456.
F. Gzde ilingir Adeline Seah Brian D. Horne Sitha Som David P. Bickford Frank E. Rheindt 《Ecology and evolution》2019,9(17):9500-9510
The southern river terrapin, Batagur affinis is one of the world's 25 most endangered freshwater turtle species. The major portion of the global population is currently found in peninsular Malaysia, with the only remnant Indochinese population in southern Cambodia. For more than a decade, wild nests in this remnant Cambodian population have been fenced and hatchlings reared in captivity. Here we amplified 10 microsatellite markers from all 136 captive individuals, obtained 2,658 presumably unlinked and neutral single nucleotide polymorphisms from 72 samples with ddRAD‐seq, and amplified 784 bp of mtDNA from 50 samples. Our results reveal that the last Indochinese population comprised only four kinship groups as of 2012, with all offspring sired from <10 individuals in the wild. We demonstrate an obvious decrease in genetic contributions of breeders in the wild from 2006–2012 and identify high‐value breeders instrumental for ex‐situ management of the contemporary genetic stock of the species. 相似文献
457.
458.
Benjamin Klempay Nestor Arandia-Gorostidi Anne E. Dekas Douglas H. Bartlett Christopher E. Carr Peter T. Doran Avishek Dutta Natalia Erazo Luke A. Fisher Jennifer B. Glass Alexandra Pontefract Sanjoy M. Som Jesse M. Wilson Britney E. Schmidt Jeff S. Bowman 《Environmental microbiology》2021,23(7):3825-3839
Concurrent osmotic and chaotropic stress make MgCl2-rich brines extremely inhospitable environments. Understanding the limits of life in these brines is essential to the search for extraterrestrial life on contemporary and relict ocean worlds, like Mars, which could host similar environments. We sequenced environmental 16S rRNA genes and quantified microbial activity across a broad range of salinity and chaotropicity at a Mars-analogue salt harvesting facility in Southern California, where seawater is evaporated in a series of ponds ranging from kosmotropic NaCl brines to highly chaotropic MgCl2 brines. Within NaCl brines, we observed a proliferation of specialized halophilic Euryarchaeota, which corresponded closely with the dominant taxa found in salterns around the world. These communities were characterized by very slow growth rates and high biomass accumulation. As salinity and chaotropicity increased, we found that the MgCl2-rich brines eventually exceeded the limits of microbial activity. We found evidence that exogenous genetic material is preserved in these chaotropic brines, producing an unexpected increase in diversity in the presumably sterile MgCl2-saturated brines. Because of their high potential for biomarker preservation, chaotropic brines could therefore serve as repositories of genetic biomarkers from nearby environments (both on Earth and beyond) making them prime targets for future life-detection missions. 相似文献