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81.
Bong Gu Lee Jun IL Yang Euna Kim Sun Woo Geum Ju-Hyeong Park Min-Kyeong Yeo 《Indoor air》2021,31(5):1553-1562
The advent of high-throughput sequencing methods allowed researchers to fully characterize microbial community in environmental samples, which is crucial to better understand their health effects upon exposures. In our study, we investigated bacterial and fungal community in indoor and outdoor air of nine classrooms in three elementary schools in Seoul, Korea. The extracted bacterial 16S rRNA gene and fungal ITS regions were sequenced, and their taxa were identified. Quantitative polymerase chain reaction for total bacteria DNA was also performed. The bacterial community was richer in outdoor air than classroom air, whereas fungal diversity was similar indoors and outdoors. Bacteria such as Enhydrobacter, Micrococcus, and Staphylococcus that are generally found in human skin, mucous membrane, and intestine were found in great abundance. For fungi, Cladosporium, Clitocybe, and Daedaleopsis were the most abundant genera in classroom air and mostly related to outdoor plants. Bacterial community composition in classroom air was similar among all classrooms but differed from that in outdoor air. However, indoor and outdoor fungal community compositions were similar for the same school but different among schools. Our study indicated the main source of airborne bacteria in classrooms was likely human occupants; however, classroom airborne fungi most likely originated from outdoors. 相似文献
82.
Kris Van Looy Jonathan D. Tonkin Mathieu Floury Catherine Leigh Janne Soininen Stefano Larsen Jani Heino N. LeRoy Poff Michael Delong Sonja C. Jhnig Thibault Datry Núria Bonada Juliette Rosebery Aurlien Jamoneau Steve J. Ormerod Kevin J. Collier Christian Wolter 《河流研究与利用》2019,35(2):107-120
Resilience in river ecosystems requires that organisms must persist in the face of highly dynamic hydrological and geomorphological variations. Disturbance events such as floods and droughts are postulated to shape life history traits that support resilience, but river management and conservation would benefit from greater understanding of the emergent effects in communities of river organisms. We unify current knowledge of taxonomic‐, phylogenetic‐, and trait‐based aspects of river communities that might aid the identification and quantification of resilience mechanisms. Temporal variations in river productivity, physical connectivity, and environmental heterogeneity resulting from floods and droughts are highlighted as key characteristics that promote resilience in these dynamic ecosystems. Three community‐wide mechanisms that underlie resilience are (a) partitioning (competition/facilitation) of dynamically varying resources, (b) dispersal, recolonization, and recruitment promoted by connectivity, and (c) functional redundancy in communities promoted by resource heterogeneity and refugia. Along with taxonomic and phylogenetic identity, biological traits related to feeding specialization, dispersal ability, and habitat specialization mediate organism responses to disturbance. Measures of these factors might also enable assessment of the relative contributions of different mechanisms to community resilience. Interactions between abiotic drivers and biotic aspects of resource use, dispersal, and persistence have clear implications for river conservation and management. To support these management needs, we propose a set of taxonomic, phylogenetic, and life‐history trait metrics that might be used to measure resilience mechanisms. By identifying such indicators, our proposed framework can enable targeted management strategies to adapt river ecosystems to global change. 相似文献
83.
We report a new form of congenital muscular dystrophy (CMD) in 4 patients from three unrelated families with probable autosomal-recessive inheritance. All patients had the clinical characteristics of merosin-positive congenital muscular dystrophy, but had marked mental retardation. The disease was slowly progressive and 1 patient died from dilated cardiomyopathy at the age of 13 years. In addition to dystrophic changes with necrosis and regeneration in muscle, the most striking finding was mitochondrial depletion in the center of the sarcoplasm. Mitochondria at the periphery of fibers were markedly enlarged ("megaconial" appearance) with complicated cristae, and contained a normal amount of mitochondrial DNA by in situ hybridization. Mitochondrial enlargement may represent functional compensation for mitochondrial depletion in the central sarcoplasm, where myofibrillar degeneration occurred. 相似文献
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85.
A. S. Bedekar J. J. Feng S. Krishnamoorthy - S. Krishnamoorthy is currently with Baxter Healthcare Corporation Round Lake IL. K. G. Lim G. T. R. Palmore S. Sundaram 《Chemical Engineering Communications》2008,195(3):256-266
Biofuel cells are devices that use biocatalysts (enzymes or microbes) to convert biochemical energy directly into electrical energy. Microfluidic biofuel cells exploit the lack of active mixing at microscale dimensions to eliminate the use of proton exchange membranes that separate anolyte and catholyte streams. Simulation of this system, by solving the governing 3-D conservation equations (flow, species transport), reveals that oxygen availability limits the performance of the cathode. An exponential decay in the availability of oxygen at the cathode is observed along the length of the microchannel, indicating that increasing the number of electrode pairs reduces the overall current density. This conclusion is consistent with experimental observations. Increasing electrolyte flow rates can reduce the mass transport limitations by decreasing the diffusion boundary-layer thickness, but disparity between the flow rates of the anolyte and catholyte can induce wastage of dissolved oxygen. 相似文献
86.
The physicochemical properties and antioxidant properties of bokbunja, a Korean black raspberry, were clarified and compared with blueberry, cranberry, raspberry, and strawberry. The amount of soluble solids was significantly (p<0.05) lower in bokbunja than in other berries, whereas the pH of bokbunja was significantly (p<0.05) higher. Analysis of the total phenolic, flavonoid, and anthocyanin contents found that bokbunja had the highest, while the others were ranked in the order of raspberry>blueberry>cranberry>strawberry. The content of ellagic acid (147.3 mg/100 g of FW) also was highest in bokbunja. The antioxidant activities of bokbunja, assessed based on DPPH, ABTS, and ferric reducing antioxidant power (FRAP) assays, were higher than for other berries. Bokbunja is a healthier antioxidant source than other berries. 相似文献
87.
Macroinvertebrate drift was sampled at 15 sites along the Tongariro River, New Zealand above and below two hydroelectric dams. Sixty‐seven invertebrate taxa were collected in the drift. Trichoptera (31) were the most diverse, followed by Diptera (13), Ephemeroptera (8) and Plecoptera (8). However, chironomidae were the numerically dominant taxa in the drift throughout the river and represented over 80% of all animals collected. Of these, Orthocladiinae and Diamesinae were the most abundant. Taxonomic richness declined with distance downstream and peaked at sites with intermediate levels of periphyton biomass. The per cent of Ephemeroptera, Plecoptera and Trichoptera (EPT) was 3–4 times higher in the unregulated section of the river and declined exponentially with both distance downstream and increase in periphyton biomass, but densities were similar along the river. Of the measured environmental variables periphyton biomass was most closely linked with drift community structure. Periphyton biomass was six times higher in the lower section of the river than the upper unregulated section. The autocorrelation between periphyton biomass and distance downstream complicates the interpretation of results. However, because of the distinct differences between above and below dam sections of river in periphyton biomass and the strong link between it and invertebrate drift we suggest that the alteration of flow patterns by the hydroelectric dams and the associated shift in periphyton biomass is the most likely explanation for invertebrate drift patterns in the river. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
88.
四、第一代表面工程方法 1.固态淬火(硬化) 加热的各项工艺参数、材料的初始组织和机件的具体几何形状,都对材料的组织和性能、淬硬的深度和机件的表面质量有很大的影响。在我们的试验研究中,对各种不同的结构钢和工具钢以及某些铁进行了研究,采用的加热方式为将需要淬硬的整个表面同时加热等。对于退火状态的和整体淬硬的多,硬化度分别达到3.6~3.7和1.5~1.7。钢的硬度达到HRC65~68,显微硬度为10~11GPa,硬化的深度为 1.5-2.0mm。 在各种钢中,会产生残余的压缩应力,还会形成细粒组织,并… 相似文献
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90.