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1.
《Engineering Applications of Artificial Intelligence》2007,20(6):735-744
Harmful algal blooms, which are considered a serious environmental problem nowadays, occur in coastal waters in many parts of the world. They cause acute ecological damage and ensuing economic losses, due to fish kills and shellfish poisoning as well as public health threats posed by toxic blooms. Recently, data-driven models including machine-learning (ML) techniques have been employed to mimic dynamics of algal blooms. One of the most important steps in the application of a ML technique is the selection of significant model input variables. In the present paper, we use two extensively used ML techniques, artificial neural networks (ANN) and genetic programming (GP) for selecting the significant input variables. The efficacy of these techniques is first demonstrated on a test problem with known dependence and then they are applied to a real-world case study of water quality data from Tolo Harbour, Hong Kong. These ML techniques overcome some of the limitations of the currently used techniques for input variable selection, a review of which is also presented. The interpretation of the weights of the trained ANN and the GP evolved equations demonstrate their ability to identify the ecologically significant variables precisely. The significant variables suggested by the ML techniques also indicate chlorophyll-a (Chl-a) itself to be the most significant input in predicting the algal blooms, suggesting an auto-regressive nature or persistence in the algal bloom dynamics, which may be related to the long flushing time in the semi-enclosed coastal waters. The study also confirms the previous understanding that the algal blooms in coastal waters of Hong Kong often occur with a life cycle of the order of 1–2 weeks. 相似文献
2.
《Catalysis communications》2007,8(3):241-246
A simple method for evaluating the surface acidity of different cation-exchanged montmorillonite (mont) clay catalysts, Mn+-mont (Mn+=Al3+, Fe3+, Cr3+, Zn2+, Ni2+, Cu2+, and H+), involving treatment with pyridine is described. After treating with pyridine, the samples were heated at 120 °C and the FT-IR spectra were directly recorded in the region 1650 and 1350 cm−1. The data obtained show the presence of both Lewis and Brønsted acid sites. The activities of the catalysts to bring about Brønsted acid catalysed esterification of succinic acid with iso-butanol to yield di-(iso-butyl) succinate have been studied. The Brønsted acidity data obtained for Mn+-mont correlated well with activity in the esterification reaction. The activities of the catalysts were found to decrease in the order of exchange ions Al3+ > Fe3+ > Cr3+ > Zn2+ > Ni2+ > Cu2+ > Na+-mont. They also correlated well with the charge to radius ratio of the cations. The catalysts exchanged with trivalent cations showed stronger absorption bands attributed to Brønsted acidity (1540 cm−1) whereas those exchanged with divalent cations showed an increased Lewis acidity (1450 cm−1) and reduced Brønsted acidity along with charge to radius ratio. Zn2+-, Cu2+- and Ni2+-exchanged clays showed an additional peak around 1605 cm−1 which is attributed to the pyridine adsorption on surface sites through its π electrons. The method suggested here to evaluate the acidity is suitable for active sites which are thermally unstable such as water molecules in the hydration shell of a cation in exchanged clay. 相似文献
3.
4.
《Microporous and mesoporous materials》2007,98(1-3):16-20
Deprotonation of 4,4′-biphenyldicarboxylic acid (H2BPDC) with triethylamine followed by the copolymerization with Y(III) in N,N-dimethylformamide (DMF) at room temperature yields a new three-dimensional (3-D) porous metal–organic coordination network, [Y2(BPDC)3(DMF)2(H2O)2]n · (DMF)n · (H2O)n (1). Compound 1 (C24.50H19N1.50O9Y) crystallizes in the triclinic P-1 space group (a = 8.220 (2), b = 13.998 (4), c = 14.212 (4) Å, α = 111.058 (5)°, β = 90.187 (5)°, γ = 94.318 (5)°, V = 1520.9 (7) Å3, and Z = 2). X-ray crystallography reveals that 1 consists of a 3-D framework contained open 1-D channels with the dimension of 5 × 10 Å along the crystallographic a axis. The adsorption measurements show that compound 1 can adsorb N2, Ar and CO2 into its pores. The adsorption isotherms for MeOH and H2O were also measured. 相似文献
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6.
介绍了臭味层次分析法(FPA)培训内容及其在上海市饮用水臭味识别中的应用。结果表明,经过培训的FPA臭味识别小组能够对水样中不同种类的异臭味进行定性和定量的评价分析;臭味检测人员对上海市水体中含有的典型致臭土霉味物质甲基异莰醇-2和腥臭味物质二甲基三硫的嗅阈值可分别达到1.69ng/L和24.4ng/L,并对这两种物质的强度等级评价有较好的重现性。采用FPA评价上海市地区原水及不同供水区域自来水的臭味特征及加标后不同浓度条件下的臭味强度特征,结果表明,FPA优于现行使用的臭味评价方法,能够及时、快速地反映水质问题,是可靠的感官分析方法。 相似文献
7.
Uniform ordered mesoporous ZnCo2O4 nanospheres for super-sensitive enzyme-free H2O2 biosensing and glucose biofuel cell applications 总被引:1,自引:0,他引:1
Cui Shiqiang Li Li Ding Yaping Zhang Jiangjiang Wu Qingsheng Hu Zongqian 《Nano Research》2017,10(7):2482-2494
Uniform,ordered mesoporous ZnCo2O4 (meso-ZnCo2O4) nanospheres were successfully synthesized using a sacrificing template method.The meso-ZnCo2O4 nanospheres were used for the first time for H2O2 biosensing and in glucose biofuel cells (GBFCs) as an enzyme mimic.The meso-ZnCo2O4 nanospheres not only exhibited excellent catalytic performance in the H2O2 sensor,achieving a high sensitivity (658.92 μA·mM-1·cm-2) and low detection limit (0.3 nM at signal-to-noise ratio (S/N) =3),but also performed as an excellent cathode material in GBFCs,resulting in an open circuit voltage of 0.83 V,maximum power density of 0.32 mW·cm-2,and limiting current density of 1.32 mA·cm-2.The preeminent catalytic abilities to H2O2 and glucose may be associated with the large specific surface area of the mesoporous structure in addition to the intrinsic catalytic activity of ZnCo2O4.These significant findings provide a successful basis for developing methods for the supersensitive detection of H2O2 and enriching catalytic materials for biofuel cells. 相似文献
8.
X-ray photoelectron spectroscopy of Ni-and Co-bis (dimethylglyoximato)complexes within a Na-X matrix
《Zeolites》1983,3(2):102-105
X-ray photoelectron spectroscopy is used to study the formation and location of Ni2+- and Co2+-bis(dimethylglyoximato) complexes following the reaction of Ni2+- and Co2+-exchanged Na-X zeolites with dimethylglyoxime. The formation of the complexes and the location within or on the outer surface of the zeolite matrix is sensitive to the reaction conditions and the sequence of reaction steps. 相似文献
9.
《Water research》1986,20(7):847-850
The phenomenon of complete substrate conversion within biological reactors in the presence of toxic compounds, called the Reactor Resistance to Inhibition (RRI), has been investigated. It was theoretically demonstrated that the RRI value, which means the highest concentration of inhibitor by which complete substrate conversion is possible, depends on liquid detention time. The excess detention time over that required for complete conversion, imply the existence of a “reserve” reaction potential. The value of this “reserve” can be reduced by inhibitor action with no influence on the observed substrate conversion rate. The influence of detention time on biological denitrification in Packed Bed Reactors in the presence of chromium Cr6+ was investigated. The RRI value for 1 h detention time was 1.5 mg l−1 Cr6+. For 3 h detention time the RRI value was 22 mg l−1 Cr6+. The relationship between the RRI value and detention time was linear. 相似文献
10.
To investigate the shut-cut nitrification characteristics of aerobic granule,an aerobic granular sequencing batch airlift reactor(AG-SBAR) was carried out with mixed carbon sources of sodium acetate and glucose at 10±1 ℃.Results indicated that ammonia oxidizing bacteria was accumulated inside the aerobic granules and the reactor performed stably with shut-cut nitrification for a long term at low temperature.During the stable operation period,the effluent ammonia nitrogen concentration was maintained at 13.6 mg/L without nitrate and nitrite when the COD/N ratio was 20:1.However,the effluent concentration of ammonia nitrogen was below 0.5 mg/L with effluent nitrosation ratio of 96.7% on average when the COD/N ratio was reduced to 15:1 and 10:1.And the effluent phosphorus concentration was less than 0.4 mg/L during the stable period with the sludge retention time of 30 d.The phosphorus removal efficiency was not strongly influenced by the adjustment of COD/N ratio in this experiment.The removal efficiencies for COD,NH4+-N and PO43--P were 91.3%-94.6%,97.9%-99.7% and 97.1%-99.5%,respectively. 相似文献