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151.
Adrian Hoppenstedt 《城市环境设计》2008,(1):31-31
第一,地区的特点现在变得越来越重要。在全球化不断发展的今天,景观的保护和发展作为生活质量构成的一部分,已经变得越来越重要了。资源的保护实际上要比物种的保护和生物种类的保护更加重要,因为景观必须要有一个更加全面的想法,这样才能有非常好的景观设计。我们在考虑景观的时候必须要考虑景观的因素和当地的情况。现在我们不断地标准化,不断地趋同、 相似文献
152.
The wind energy market is in full growth in Quebec but technical difficulties due to cold climate conditions have occurred for most of the existing projects. Thus, icing simulations were carried out on a 0.2 m NACA 63 415 blade profile in the refrigerated wind tunnel of the Anti‐icing Materials International Laboratory (AMIL). The shapes and masses of the ice deposits were measured, as well as the lift and drag forces of the iced profiles. Scaling was carried out based on the 1.8 MW–Vestas V80 wind turbine technical data, for three different radial positions and two in‐fog icing conditions measured at the Murdochville wind farm in the Gaspé Peninsula. For both icing events, the mass of ice accumulated on the blade profile increased with an increase in the radial position. In wet regime testing (first icing event), glaze formed mostly near the leading edge and on the pressure side. It also accumulated by run‐off on the trailing edge of the outer half of the blade. In dry‐regime testing (second icing event), rime mostly accreted on the leading edge and formed horns. For both icing events, when glaze or rime accreted on the blade profile, lift decreased and drag increased. A load calculation using the blade element theory shows that drag force on the entire blade becomes too large compared to lift, leading to a negative torque and the stop of the wind turbine. Torque reduction is more significant on the outer third of the blade. Setting up a de‐icing system only on the outer part of the blade would enable significant decrease of heating energy costs. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
153.
Local melting and tool slippage during friction stir spot welding of different Al-alloy base materials is examined using a
combination of detailed microscopy and temperature measurement. The stir zone peak temperature during welding is limited by
either the solidus of the alloy in question or by spontaneous melting of intermetallic particles contained in the as-received
base material. When spontaneous melting occurs this facilitates tool slippage at the contact interface. Accurate stir zone
temperature and grain size measurements are essential elements when estimating the strain rate using the Zener–Hollomon relation.
In Al 2024 and Al 7075 spot welds spontaneous melting of second-phase particles produces a drastic reduction in strain rate
values. In Al 5754 and Al 6061 spot welds there is a strong correlation between tool rotational speed and estimated strain
values. Local melted films dissolve rapidly in the high temperature stir zone and when the spot weld cools to room temperature
following welding. Evidence of local melting is observed in Al 7075 friction stir spot welded joints made using a combination
of rapid quenching, high plunge rates, and extremely short dwell time settings. 相似文献
154.
155.
Moeck Christian Merk Markus Radny Dirk Auckenthaler Adrian Schirmer Mario Gabriel Thomas 《Grundwasser》2022,27(3):187-196
Grundwasser - Eine nachhaltige Wasserversorgung in urbanen Gebieten stellt aufgrund des Nutzungsdrucks sowie vielfältiger anthropogener Einträge eine große Herausforderung dar.... 相似文献
156.
Daniel MARECI Romeu CHELARIU Adrian CAILEAN Florin BRINZA Georgiana BOLAT Doina Margareta GORDIN 《中国有色金属学会会刊》2015,(1):345-353
比较了未再结晶和再结晶Ti12Mo5Ta合金、未再结晶Ti12Mo合金和工业用纯钛(cp-Ti)在0.9%生理盐水(pH 2.3)中37°C下的电化学行为。从阳极极化曲线中得到了极低的钝化电流密度(10-6 A/cm2),这表明所有样品在酸性0.9%NaCl溶液中具有高的耐蚀性能。采用扫描电子显微镜(SEM)观察样品的表面形貌,发现所有样品表面受到了相同的腐蚀,而且经阳极动电位极化测试后的样品表面没有出现点蚀、裂纹或其它缺陷。使用等效电路模拟电化学阻抗谱(EIS)数据,以表征样品表面且更好地理解Mo和Ta的添加对cp-Ti及再结晶的影响。EIS结果证实,在开路电位下,所有样品在0.9%NaCl溶液(pH 2.3)中产生钝化(极化电阻约为105Ω·cm2)。在37°C时,样品在0.9%NaCl溶液中(pH 2.3)的耐蚀性顺序为:再结晶Ti12Mo5Ta未再结晶Ti12Mo5Ta未再结晶Ti12Mocp-Ti。 相似文献
157.
Different bacterial models for in vitro induction of non‐cavitated enamel caries‐like lesions: Microhardness and polarized light miscroscopy analyses 下载免费PDF全文
Priscila Hernández De Campos Mariane Emi Sanabe Jonas Almeida Rodrigues Danilo Antonio Duarte Maria Teresa Botti Rodrigues Santos Renata Oliveira Guaré cristiane Duque Adrian Lussi Michele Baffi Diniz 《Microscopy research and technique》2015,78(6):444-451
The aim of this study was to compare different bacterial models for in vitro induction of non‐cavitated enamel caries‐like lesions by microhardness and polarized light microscopy analyses. One hundred blocks of bovine enamel were randomly divided into four groups (n = 25) according to the bacterial model for caries induction: (A) Streptococcus mutans, (B) S. mutans and Lactobacillus acidophilus, (C) S. mutans and L. casei, and (D) S. mutans, L. acidophilus, and L. casei. Within each group, the blocks were randomly divided into five subgroups according to the duration of the period of caries induction (4–20 days). The enamel blocks were immersed in cariogenic solution containing the microorganisms, which was changed every 48 h. Groups C and D presented lower surface hardness values (SMH) and higher area of hardness loss (ΔS) after the cariogenic challenge than groups A and B (P < 0.05). As regards lesion depth, under polarized light microscopy, group A presented significantly lower values, and groups C and D the highest values. Group B showed a higher value than group A (P < 0.05). Groups A and B exhibited subsurface caries lesions after all treatment durations, while groups C and D presented erosion‐type lesions with surface softening. The model using S. mutans, whether or not it was associated with L. acidophilus, was less aggressive and may be used for the induction of non‐cavitated enamel caries‐like lesions. The optimal period for inducing caries‐like lesions was 8 days. Microsc. Res. Tech. 78:444–451, 2015. © 2015 Wiley Periodicals, Inc. 相似文献
158.
The short-term effect of air pollution on cardiovascular mortality in Tianjin, China: comparison of time series and case-crossover analyses 总被引:2,自引:0,他引:2
Guo Y Barnett AG Zhang Y Tong S Yu W Pan X 《The Science of the total environment》2010,409(2):300-306
Background
Many studies have illustrated that ambient air pollution negatively impacts on health. However, little evidence is available for the effects of air pollution on cardiovascular mortality (CVM) in Tianjin, China. Also, no study has examined which strata length for the time-stratified case-crossover analysis gives estimates that most closely match the estimates from time series analysis.Objectives
The purpose of this study was to estimate the effects of air pollutants on CVM in Tianjin, China, and compare time-stratified case-crossover and time series analyses.Method
A time-stratified case-crossover and generalized additive model (time series) were applied to examine the impact of air pollution on CVM from 2005 to 2007. Four time-stratified case-crossover analyses were used by varying the stratum length (Calendar month, 28, 21 or 14 days). Jackknifing was used to compare the methods. Residual analysis was used to check whether the models fitted well.Results
Both case-crossover and time series analyses show that air pollutants (PM10, SO2 and NO2) were positively associated with CVM. The estimates from the time-stratified case-crossover varied greatly with changing strata length. The estimates from the time series analyses varied slightly with changing degrees of freedom per year for time. The residuals from the time series analyses had less autocorrelation than those from the case-crossover analyses indicating a better fit.Conclusion
Air pollution was associated with an increased risk of CVM in Tianjin, China. Time series analyses performed better than the time-stratified case-crossover analyses in terms of residual checking. 相似文献159.
Yuming Guo Shilu Tong Adrian G. Barnett Xiaochuan Pan 《The Science of the total environment》2010,408(20):4446-1817
Background
A number of epidemiological studies have examined the adverse effect of air pollution on mortality and morbidity. Also, several studies have investigated the associations between air pollution and specific-cause diseases including arrhythmia, myocardial infarction, and heart failure. However, little is known about the relationship between air pollution and the onset of hypertension.Objective
To explore the risk effect of particulate matter air pollution on the emergency hospital visits (EHVs) for hypertension in Beijing, China.Methods
We gathered data on daily EHVs for hypertension, fine particulate matter less than 2.5 μm in aerodynamic diameter (PM2.5), particulate matter less than 10 μm in aerodynamic diameter (PM10), sulfur dioxide, and nitrogen dioxide in Beijing, China during 2007. A time-stratified case-crossover design with distributed lag model was used to evaluate associations between ambient air pollutants and hypertension. Daily mean temperature and relative humidity were controlled in all models.Results
There were 1,491 EHVs for hypertension during the study period. In single pollutant models, an increase in 10 μg/m3 in PM2.5 and PM10 was associated with EHVs for hypertension with odds ratios (overall effect of five days) of 1.084 (95% confidence interval (CI): 1.028, 1.139) and 1.060% (95% CI: 1.020, 1.101), respectively.Conclusion
Elevated levels of ambient particulate matters are associated with an increase in EHVs for hypertension in Beijing, China. 相似文献160.
Eduard A. Stefanescu 《Polymer》2010,51(24):5823-5832
We describe the influence of calcium copper titanate (CCTO), and montmorillonite (MMT) on the thermo-mechanical and dielectric properties of poly(methyl methacrylate) PMMA-based composites prepared by an in-situ, thermally activated, radical polymerization for multifunctional structural capacitor applications. MMT was used for its ability to disperse and suspend the CCTO particles through the generation of viscous monomer slurries. X-ray diffraction (XRD) measurements together with transmission electron microscopy (TEM) analysis revealed that the MMT platelets were present in both intercalated and exfoliated morphologies within the polymer matrix. The filler addition was found to improve the thermal stability and the glass transition temperature of PMMA in the composites. Furthermore, the elastic stiffness and dielectric constant of the resultant composites were observed to increase monotonically with filler loading. By contrast, the dielectric breakdown strength of the composite samples was found to diminish with increasing filler loading. 相似文献