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121.
Dirk C. Jordan Sarah R. Kurtz Kaitlyn VanSant Jeff Newmiller 《Progress in Photovoltaics: Research and Applications》2016,24(7):978-989
Published data on photovoltaic (PV) degradation measurements were aggregated and re‐examined. The subject has seen an increased interest in recent years resulting in more than 11 000 degradation rates in almost 200 studies from 40 different countries. As studies have grown in number and size, we found an impact from sampling bias attributable to size and accuracy. Because of the correlational nature of this study we examined the data in several ways to minimize this bias. We found median degradation for x‐Si technologies in the 0.5–0.6%/year range with the mean in the 0.8–0.9%/year range. Hetero‐interface technology (HIT) and microcrystalline silicon (µc‐Si) technologies, although not as plentiful, exhibit degradation around 1%/year and resemble thin‐film products more closely than x‐Si. Several studies showing low degradation for copper indium gallium selenide (CIGS) have emerged. Higher degradation for cadmium telluride (CdTe) has been reported, but these findings could reflect a convolution of less accurate studies and longer stabilization periods for some products. Significant deviations for beginning‐of‐life measurements with respect to nameplate rating have been documented over the last 35 years. Therefore, degradation rates that use nameplate rating as reference may be significantly impacted. Studies that used nameplate rating as reference but used solar simulators showed less variation than similar studies using outdoor measurements, even when accounting for different climates. This could be associated with confounding effects of measurement uncertainty and soiling that take place outdoors. Hotter climates and mounting configurations that lead to sustained higher temperatures may lead to higher degradation in some, but not all, products. Wear‐out non‐linearities for the worst performing modules have been documented in a few select studies that took multiple measurements of an ensemble of modules during the lifetime of the system. However, the majority of these modules exhibit a fairly linear decline. Modeling these non‐linearities, whether they occur at the beginning‐of‐life or end‐of‐life in the PV life cycle, has an important impact on the levelized cost of energy. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
122.
Henry Hieslmair Jesse Appel Jai Kasthuri Jason Guo Bayard Johnson Jeff Binns 《Progress in Photovoltaics: Research and Applications》2016,24(11):1448-1457
The injection‐level‐dependent (ILD) lifetime of the silicon wafer impacts many characteristics of the final photovoltaic cell. While efficiency is commonly understood to be impacted by the silicon bulk lifetime (at the maximum power point injection level), this work demonstrates the wide ranging impacts of ILD lifetime on the Voc, the fill factor (FF), the diode ideality factor m, and the dim light response. Instead of a two‐diode model, we utilize a boundary + ILD bulk lifetime model to analyze a commercial passivated emitter rear contact (PERC) cell featuring an AlOx dielectric rear passivation. The ILD lifetime is directly measured and used to calculate the bulk recombination current across injection levels. With this boundary + ILD lifetime model, we demonstrate the role of the ILD lifetime on many cell parameters in this PERC cell. For most high efficiency commercial p‐type monocrystalline solar cells, the typically lower bulk lifetime at the maximum power point versus the lifetime at the open circuit point reduces the measured FF and pseudo‐FF. This work illustrates that for a commercial PERC cell with AlOx rear passivation, the ILD lifetime is the primary mechanism behind reduced FF, ideality factors greater than 1, and the source of the J02 term in the two‐diode model. The crucial implications of this work are not only to better understand commercial PERC cell loss mechanisms but also to encourage a focus on different metrics in cell diagnostics. One such metric is the Voc at 0.1 or 0.05 suns. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
123.
Patricia A. Fair Jeff Adams Thomas C. Hulsey Magali Houde Ed Wirth Eric Zolman Gregory D. Bossart 《The Science of the total environment》2010,408(7):1577-1597
Polychlorinated biphenyls (PCBs), chlorinated pesticides (i.e., dichlorodiphenyltrichloroethane (DDT) and its metabolites, chlordanes (CHLs), dieldrin, hexachlorobenzene (HCB), and mirex), polybrominated diphenyl ethers (PBDEs), perfluorinated chemicals (PFCs), and polyaromatic hydrocarbons (PAHs) were measured in blubber biopsy samples collected from 139 wild bottlenose dolphins (Tursiops truncatus) during 2003-2005 in Charleston (CHS), SC and the Indian River Lagoon (IRL), FL. Dolphins accumulated a similar suite of contaminants with ∑ PCB dominating (CHS 64%, IRL 72%), followed by ∑ DDT (CHS 20%, IRL 17%), ∑ CHLs (CHS 7%; IRL 7%), ∑ PBDE (CHS 4%, IRL 2%), PAH at 2%, and dieldrin, PFCs and mirex each 1% or less. Together ∑ PCB and ∑ DDT concentrations contributed ∼ 87% of the total POCs measured in blubber of adult males. ∑ PCBs in adult male dolphins exceed the established PCB threshold of 17 mg/kg by a 5-fold order of magnitude with a 15-fold increase for many animals; 88% of the dolphins exceed this threshold. For male dolphins, CHS (93,980 ng/g lipid) had a higher ∑ PCBs geomean compared to the IRL (79,752 ng/g lipid) although not statistically different. In adult males, the PBDE geometric mean concentration was significantly higher in CHS (5920 ng/g lipid) than the IRL (1487 ng/g). Blubber ∑ PFCs concentrations were significantly higher in CHS dolphins. In addition to differences in concentration of PCB congeners, ∑ PBDE, TEQ, ∑ CHLs, mirex, dieldrin, and the ratios ∑ DDE/∑DDT and trans-nonachlor/cis-nonachlor were the most informative for discriminating contaminant loads in these two dolphin populations. Collectively, the current ∑ PCB, ∑ DDT, and ∑ PBDEs blubber concentrations found in CHS dolphins are among the highest reported values in marine mammals. Both dolphin populations, particularly those in CHS, carry a suite of organic chemicals at or above the level where adverse effects have been reported in wildlife, humans, and laboratory animals warranting further examination of the potential adverse effects of these exposures. 相似文献
124.
Pei-Ying Chiang May-chen Kuo Jessy Lee C.-C. Jay Kuo Todd Richmond Milton Rosenberg Jeff Lund Kip Haynes Lindsay Armstrong 《Journal of Visual Communication and Image Representation》2010,21(3):200-209
The Automated Metadata Indexing and Analysis (AMIA) project aims to provide an effective digital asset management (DAM) tool for large digital asset databases. We began with text-based indexing since it is still the most reliable approach as compared with other content-based media features. AMIA not only searches for the text of the file name, but also utilizes embedded information such as the metadata in Maya files. The AMIA system builds a linked map between all dependency files. We present an approach of preserving previously established metadata created by the old DAM tools, such as AlienBrain, and integrating them into the new system. Findings indicate that AMIA has significantly improved search performance comparing to previous DAM tools. Finally, the ongoing and future work in the AMIA project is described. 相似文献
125.
126.
127.
Jeff Sherman 《电子与电脑》2010,(11):56-58
硅芯片(silicon)及封装技术的进展使得尺寸缩小的产品需要更多的电量,DualCoolTM NexFETTM电源MOSFET结合新一代硅产品技术与能够在标准体积尺寸中达到上端降温(topside cooling)效果的封装,这些技术的结合使得效率、功率密度(power density)及可靠度达到新境界,本文将着重在效能优点方面说明这些新技术。 相似文献
128.
Jaehak Jeong Narayanan Kannan Jeff Arnold Roger Glick Leila Gosselink Raghavan Srinivasan 《Water Resources Management》2010,24(15):4505-4527
Increasing urbanization changes runoff patterns to be flashy and instantaneous with decreased base flow. A model with the
ability to simulate sub-daily rainfall–runoff processes and continuous simulation capability is required to realistically
capture the long-term flow and water quality trends in watersheds that are experiencing urbanization. Soil and Water Assessment
Tool (SWAT) has been widely used in hydrologic and nonpoint sources modeling. However, its subdaily modeling capability is
limited to hourly flow simulation. This paper presents the development and testing of a sub-hourly rainfall–runoff model in
SWAT. SWAT algorithms for infiltration, surface runoff, flow routing, impoundments, and lagging of surface runoff have been
modified to allow flow simulations with a sub-hourly time interval as small as one minute. Evapotranspiration, soil water
contents, base flow, and lateral flow are estimated on a daily basis and distributed equally for each time step. The sub-hourly
routines were tested on a 1.9 km2 watershed (70% undeveloped) near Lost Creek in Austin Texas USA. Sensitivity analysis shows that channel flow parameters
are more sensitive in sub-hourly simulations (Δt = 15 min) while base flow parameters are more important in daily simulations (Δt = 1 day). A case study shows that the sub-hourly SWAT model reasonably reproduces stream flow hydrograph under multiple storm
events. Calibrated stream flow for 1 year period with 15 min simulation (R
2 = 0.93) shows better performance compared to daily simulation for the same period (R
2 = 0.72). A statistical analysis shows that the improvement in the model performance with sub-hourly time interval is mostly
due to the improvement in predicting high flows. The sub-hourly version of SWAT is a promising tool for hydrology and non-point
source pollution assessment studies, although more development on water quality modeling is still needed. 相似文献
129.
The ebullition of hydrogen, carbon monoxide, methane, carbon dioxide and total gaseous mercury from the Cornwall Area of Concern 总被引:1,自引:0,他引:1
Poissant L Constant P Pilote M Canário J O'Driscoll N Ridal J Lean D 《The Science of the total environment》2007,381(1-3):256-262
This paper reports the first ebullitive fluxes of hydrogen (H2), carbon monoxide (CO), methane (CH4), carbon dioxide (CO2) and total gaseous mercury (TGM) from the Cornwall Area of Concern (CAC). Although sediments were contaminated with mercury, bubbling was a negligible source of mercury for the global atmosphere. Indeed, the average emission of TGM through ebullition was 0.04 pg m(-2) h(-1). Measurements of H2, CO, CH4 and CO2 trapped gas concentrations and fluxes were used as indicators of diagenesis processes. The CAC represented a significant regional source of CH4 since the estimated ebullitive fluxes (3.5 mg m(-2) h(-1)) were similar to the CH4 emissions measured above typical flooded freshwater wetlands. As molecular diffusion is known as the main pathway of CO2 transport from water to the atmosphere, CO2 ebullitive fluxes were weak (0.39 mg m(-2) h(-1)). Bubbling of CO (1.6 microg m(-2) h(-1)) was 10 folds less important than CO fluxes measured over flooded freshwater wetlands. Finally, H2 emissions (0.001 microg m(-2) h(-1)) were negligible since the level of this trace gas is tightly regulated by microorganisms in anaerobic environments. 相似文献
130.
Volk C Kaplan LA Robinson J Johnson B Wood L Zhu HW LeChevallier M 《Environmental science & technology》2005,39(11):4258-4264
Natural organic matter (NOM) in drinking water supplies can provide precursors for disinfectant byproducts, molecules that impact taste and odors, compounds that influence the efficacy of treatment, and other compounds that are a source of energy and carbon for the regrowth of microorganisms during distribution. NOM, measured as dissolved organic carbon (DOC), was monitored daily in the White River and the Indiana-American water treatment plant over 22 months. Other parameters were either measured daily (UV-absorbance, alkalinity, color, temperature) or continuously (turbidity, pH, and discharge) and used with stepwise linear regressions to predict DOC concentrations. The predictive models were validated with monthly samples of the river water and treatment plant effluent taken over a 2-year period after the daily monitoring had ended. Biodegradable DOC (BDOC) concentrations were measured in the river water and plant effluent twice monthly for 18 months. The BDOC measurements, along with measurements of humic and carbohydrate constituents within the DOC and BDOC pools, revealed that carbohydrates were the organic fraction with the highest percent removal during treatment, followed by BDOC, humic substances, and refractory DOC. 相似文献