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81.
Ingram Kathleen M.; Corning Alexandra F.; Schmidt Lyle D. 《Canadian Metallurgical Quarterly》1996,43(2):218
Stressful experiences and their effects on the psychological well-being of 113 homeless women and 116 low-income housed women were investigated. Measures of victimization assessed multiple dimensions of this construct, including criminal victimization, sexual harassment, and sexual abuse. Measures of current daily environmental hassles and quality of family environment while growing up also were included. Additional measures assessed positive and negative interpersonal exchanges, sense of coherence, and overall psychological distress. Regression analyses indicated that victimization experiences were significant predictors of psychological well-being for both samples. Results also highlighted the importance of investigating both the positive and negative dimensions of interpersonal influences as well as internal resources, and suggested that these resources for coping with stress may be differentially perceived and utilized by these groups. These findings also suggest the need for specific preventive and remedial interventions to empower homeless and low-income housed women. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
82.
Alexandra?T.?Lithoxoidou Evangelos?G.?BakalbassisEmail author 《Journal of the American Oil Chemists' Society》2004,81(8):799-802
The trend in antioxidant activity of four cinnamic acid antioxidants, derived on the basis of their liquid-phase phenolic
O H bond dissociation enthalpies, is determined theoretically, with the aid of the polarizable continuum model at the density
functional theory level. Three solvents, differing in their hydrogen-bonding ability and polarity—n-heptane, acetonitrile, and ethanol—were used to model different environmental situations. The trends in solution-phase antioxidant
activity appeared different in each solvent; still, the theoretical antioxidant activity trend derived in n-heptane was in excellent agreement with the experimental one in the lipid systems and the gas-phase system. Different ortho substituents show notably different solvent effects. These results could lead to the determination of reliable antioxidant
activity trends in real-solution environments of interest in food or biological science frameworks. 相似文献
83.
Sampling frequency and accuracy of SPM flux estimates in two contrasted drainage basins 总被引:4,自引:0,他引:4
Coynel A Schäfer J Hurtrez JE Dumas J Etcheber H Blanc G 《The Science of the total environment》2004,330(1-3):233-247
The present paper is based on discharges and suspended particulate matter concentrations from a 9-years high-resolution database for the Garonne River (large plain river) covering contrasted hydrologic years, and a 12-months high frequency sampling for the Nivelle River (small mountainous river). Annual SPM fluxes in the Garonne River range from 0.6 x 10(6) t year(-1) (1997) to 3.9 x 10(6) t year(-1) (1996). In contrast, the Nivelle River transported 11 x 10(3) t year(-1) from December 1995 to December 1996. From the long-term observation of the Garonne River an empirical relation between SPM* (discharge-weighted mean annual SPM concentrations) and annual discharge was established. This relation allows estimating annual SPM fluxes for the Garonne River with less than 30% deviation from reference values for the whole range of mean annual discharge observed during the past decade. Specific (=area-normalized) annual SPM fluxes (YSPM) range from 11 to 74 t km(-2) year(-1) for the Garonne River. Comparison of these results with YSPM of the Nivelle River (69 t km(-2) year(-1) in 1996) suggests that interannual hydrological variations may have a greater impact on fluvial SPM transport than basin-specific parameters. By extracting individual SPM concentrations and corresponding discharge values from the database, different sampling frequencies were simulated and resulting SPM fluxes were then compared to reference fluxes derived from the complete database. If a deviation of simulated flux estimates from reference fluxes lower than +/-20% is accepted, the Garonne River (large plain river) must be sampled at least every 3 days (10 samples per month) and the Nivelle River every 7 h (approx. 100 samples per month). For the Garonne River this minimum sampling frequency is valid for all contrasted hydrologic years of the observation period. Below these minimum sampling frequencies, annual SPM flux estimates may greatly differ from reference fluxes (up to 200%) and there is high probability of systematic underestimation. Consequently, annual SPM flux estimates for the Garonne River derived from the empirical relation (SPM*-annual discharge) are likely to be more satisfactory (errors <30%) than estimates based on sampling frequencies lower than the minimum frequency. These findings underline the need of adapted sampling strategies for erosion assessment, reliable chemical (e.g. nutrients and pollutants) mass balances and characterisation of fluvial transport mechanisms in the world's contrasted watersheds. 相似文献
84.
Lee?HuskeyEmail author Matthew?Berman Alexandra?Hill 《The Annals of Regional Science》2004,38(1):75-92
We investigate determinants of the pattern of recent migration of Alaska Natives between rural homelands and urban areas. A review of the literature on moving in the North American North suggests that economic opportunities draw migrants, although such opportunities must be viewed in the context of the mixed subsistence-cash economy prevailing in rural areas of the region. Consequently, we model Native migration as a simultaneous decision with labor market participation in a mixed economy. Estimated equations explaining individual Alaska Native migration choices using the U.S. Census Public Use Microdata Sample (PUMS) are consistent with the model, and also suggest that perceived opportunities differ between women and men.The authors acknowledge financial support from the National Science Foundation, grant OPP-9521459. An earlier version of this paper was presented to the 1998 annual meeting of the Western Regional Science Association 相似文献
85.
Chadeau-Hyam M Tard A Bird S Le Guennec S Bemrah N Volatier JL Alpérovitch A 《Statistical methods in medical research》2003,12(3):247-260
Assuming that human exposure to BSE was through beef mechanically recovered meat (MRM) consumed as burgers and other meat products, we estimated the French consumption of different food items containing beef MRM, and compared these consumptions for French and British populations. To estimate consumption of meat products containing bovine MRM, we used dietary data from national individual and household food surveys conducted between 1980 and 1995. After reconciliation of consumption data between the available surveys and calendar year adjustments, we simulated consumption of one-thousandth of the French population. Consumption was estimated by birth cohort and gender, and for the periods 1980-89 and 1990-95 separately. Data showed that burgers (including manufactured minced meat) represented around 75-80% of the individual consumption of meat products containing MRM, and that consumption of burgers increased by 40% over the 1980-95 period. In all age groups, consumption was higher in males than in females. In both genders, the 1940-69 birth cohort had the highest mean consumption of burgers and other beef products containing MRM. Similar findings have been reported for the UK population. Estimated consumption of bovine MRM per calendar year increased markedly over the study period, concomitantly with an increase of bovine carcasses imported from the UK. Comparison of the 1980-1995 pattern of bovine MRM consumption in the UK and France indicated thatthis consumption peaked later in France than in the UK. This difference might result in different temporal pattern of vCJD incidence. 相似文献
86.
Several novel types of miniaturized electrochemical flow cells are described. The flow cells are fabricated in fluorinated ethylene propylene using a novel technique where channels with inner diameters down to 13 microm are integrated with electrodes. The channel is formed by shrinking and simultaneous melting of a heat shrink/melt tubing around a channel template (a tungsten wire) and electrodes followed by removal of the channel template. The technique allows incorporation of different electrode materials of different sizes. The electrode configuration consists of one or two working electrodes inside the channel and a counter electrode located in the channel outlet reservoir. Electrode configurations with different channel and working electrode sizes, different electrode materials including carbon fibers, glassy carbon rods, poly(tetrafluoroethylene)/carbon composite material, and platinum wires, and different arrangements have been assembled. Hydrodynamic voltammograms in dual-electrode (generator-collector) experiments indicate good potential control for cells with 25-microm channels, while there is some iR drop in cells with 13-microm channels. Cells prepared with a cylindrical working electrode tangent and perpendicular to a flow channel show a flow rate dependence consistent with thin-layer cell behavior. Electrode areas can be made in the range of 10(-10)-10(-8) m2. 相似文献
87.
Jakob PM Wang T Schultz G Hebestreit H Hebestreit A Elfeber M Hahn D Haase A 《Magma (New York, N.Y.)》2002,15(1-3):10-17
The unique characteristics of the human lung arising from low proton density and multiple air-tissue interfaces of the alveoli
cause difficulty in1H lung magnetic resonance imaging. In addition, the dominating signal from sources such as the thoracic muscle and subcutaneous
fat hampers the visualization of the lung parenchyma. In this contribution, an efficient tissue suppression technique is presented
which allows one to significantly enhance lung parenchyma visibility. A short inversion time inversion recovery (STIR) experiment
combined with a magnetization transfer (MT) experiment was used for magnetization preparation in order to suppress the signal
from muscle. A half-Fourier single-shot turbo spin-echo sequence was used as acquisition module. This approach was used to
perform lung anatomical imaging in eight healthy human subjects and five patients withcystic fibrosis. The results obtained demonstrate that with MT-STIR approach high quality human lung images can be obtained and that this
approach has the potential for the evaluation of lung pathologies. 相似文献
88.
Umer Farooq Patricia Schank Alexandra Harris Judith Fusco Mark Schlager 《Computer Supported Cooperative Work (CSCW)》2007,16(4-5):397-429
Community computing has recently grown to become a major research area in human–computer interaction. One of the objectives
of community computing is to support computer supported cooperative work among distributed collaborators working toward shared
professional goals in online communities of practice. A core issue in designing and developing community computing infrastructures
– the underlying socio-technical layer that supports communitarian activities – is sustainability. Many community computing
initiatives fail because the underlying infrastructure does not meet end user requirements; the community is unable to maintain
a critical mass of users consistently over time; it generates insufficient social capital to support significant contributions
by members of the community; or, as typically happens with funded initiatives, financial and human capital resource become
unavailable to further maintain the infrastructure. Based on more than nine years of design experience with Tapped In – an
online community of practice for education professionals – we present a case study that discusses four design interventions
that have sustained the Tapped In infrastructure and its community to date. These interventions represent broader design strategies
for developing online environments for professional communities of practice. 相似文献
89.
Springer Utaka S.; Rosas Alexandra; McGetrick John; Bowers Dawn 《Canadian Metallurgical Quarterly》2007,7(3):516
Emotion researchers often categorize angry and fearful face stimuli as "negative" or "threatening". Perception of fear and anger, however, appears to be mediated by dissociable neural circuitries and often elicit distinguishable behavioral responses. The authors sought to elucidate whether viewing anger and fear expressions produce dissociable psychophysiological responses (i.e., the startle reflex). The results of two experiments using different facial stimulus sets (representing anger, fear, neutral, and happy) indicated that viewing anger was associated with a significantly heightened startle response (p 相似文献
90.