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排序方式: 共有465条查询结果,搜索用时 15 毫秒
71.
Maki EC Rodstein J Millar JG Barbour KS Hanks LM Barbour JD 《Journal of chemical ecology》2011,37(7):714-716
Earlier work has shown that adult male Prionus californicus Motschulsky (Coleoptera: Cerambycidae) are attracted to the female-produced compound (3R,5S)-3,5-dimethyldodecanoic acid, and to a synthetic mixture of the four stereoisomers of 3,5-dimethyldodecanoic acid. Here, we report the results of field trials that tested whether or not three structurally related compounds (methyl 3,5-dimethyldodecanoate, 3,5-dimethyltridecanoic acid, and 3,5-dimethylpentadecanoic acid), present in extracts of virgin females, are attractive, and whether or not they influence attraction to 3,5-dimethyldodecanoic acid. In a trial with single components, only traps baited with the acid or its methyl ester captured more beetles than did control traps; catches to the acid were five times higher than to the methyl ester. Another trial, excluding 3,5-dimethyldodecanoic acid, confirmed the activity of the methyl ester. Finally, addition of the three compounds to 3,5-dimethyldodecanoic acid, in the ratio found in extracts from female beetles, gave a catch similar to that of traps baited with 3,5-dimethyldodecanoic acid alone. Consequently, the function of these minor compounds remains undetermined. 相似文献
72.
Markus Takkunen Jyrki Ågren Johanna Kuusisto Markku Laakso Matti Uusitupa Ursula Schwab 《Lipids》2013,48(11):1093-1102
Erythrocyte membrane fatty acid (EMFA) composition is used in the validation of food frequency questionnaires (FFQ) and the evaluation of dietary fat quality. In this cross-sectional study we aimed to investigate associations of diet with EMFA. Altogether, 1,033 randomly selected Finnish men, aged from 47 to 75 years filled in a FFQ and their EMFA composition was analyzed. Marine polyunsaturated fatty acid (PUFA) intake correlated positively with erythrocyte eicosapentaenoic and docosahexaenoic acids (r s = 0.415 and r s = 0.340, respectively, P < 0.001) and inversely with all n-6 PUFA analyzed (P < 0.001). PUFA intake from spreads and cooking fats correlated positively with alpha-linolenic (ALA), linoleic (LNA) and nervonic acids (r s = 0.229, r s = 0.160 and r s = 0.143, respectively, P < 0.001). Milk fat intake was associated with myristic and behenic acids (r s = 0.186 and r s = 0.132, respectively P < 0.001). Butter users had lower ALA and LNA proportions (mol%) than non-users (0.16 ± 0.04 vs. 0.19 ± 0.05, P < 0.001 and 7.77 ± 1.02 vs. 8.12 ± 1.11, P = 0.001). Higher PUFA intake from meat was related to decreased long-chain n-3 (P < 0.001) and increased n-6 PUFA (P < 0.001) proportions. In conclusion, EMFA composition reflects particularly well the intakes of n-3 PUFA, whereas other associations remained lower. Yet, all main sources of dietary fat were related with EMFA. The dietary effect on the nervonic acid proportion was confirmed. 相似文献
73.
Arto Rantala Pekka Kuivalainen Markku AÅberg 《Analog Integrated Circuits and Signal Processing》2001,26(1):53-61
Digital-to-analog converts utilizing neuron MOS-transistors were designed. Different DACs were implemented and characterized in order to compare various topologies. Criteria to select structures were low power, fast performance and minimal silicon area. A basic 8-bit version is implemented with only one neuron MOS-transistor and eight capacitors. The silicon area of this D/A converter is only 0.04 mm2 and the power consumption is 8.4 mW with conversion speed of 200 MS/s. An enhanced 8 and 10 bit versions utilizing neuron PMOS transistor and some extra circuitry are also proposed and tested. The silicon area of the enhanced 10 bit circuit is only 0.03mm2 while the performance is as good as in the case of the basic version. The measured differential nonlinearity is 0.38 LSB and integral nonlinearity is 0.55 LSB for the enhanced 10 bit structure. 相似文献
74.
Menhanden oil was purified by column chromatography to remove minor components. The effect of α-tocopherol (α TOH) (50–500
ppm) on the rate of formation of hydroperoxides in the original menahaden oil and in the purified menhaden triacylglycerol
(TAG) fraction was studied at 30°C in the dark. An increase in the initial rate of formation of hydroper-oxides was observed
at αTOH concentrations above 100 ppm in both substrates. The original menhaden oil oxidized more rapidly than the purified
menhaden, TAG at all antioxidant levels tested, and the presence of minor components in the menhaden oil was found to contribute
only to a limited extent to the peroxidizing effect of αTOH. The αTOH did not display any prooxidant activity at either of
the concentrations tested when the control oil was the purified menhaden TAG. Addition of ascorbyl palmitate eliminated the
initial peroxidizing effect of αTOH, and this emphasizes the participation of the α-toco-pheroxyl radical in the reactions
causing an accumulation of hydroperoxides at high concentrations of αTOH.
Presented in part at the Annual Meeting of the American Oil Chemists’ Society in San Diego, April 25–28, 2000. 相似文献
75.
Image analysis is a technique used in a number of subjects, but to date not extensively used in the geological sciences. The paper describes the way image analysis is used in the various disciplines and presents an overview of the methods and its potential uses in geology and particularly engineering geology. Emphasis is placed on the way image analysis can be applied to rock structures and textures. It is hoped that this overview will provide an introduction to the literature, which is published in a variety of related fields. Electronic Publication 相似文献
76.
Taisa Venäläinen Ursula Schwab Jyrki Ågren Vanessa de Mello Virpi Lindi Aino-Maija Eloranta Sanna Kiiskinen David Laaksonen Timo A. Lakka 《Lipids》2014,49(5):467-479
Plasma fatty acid (FA) composition is known to be an indicator of dietary fat quality, but the associations of other dietary factors with plasma FA composition remain unknown in children. We investigated the cross-sectional associations of food consumption with the proportions of FA and estimated desaturase activities in plasma cholesteryl esters (CE) and phospholipids (PL) among children. The subjects were a population sample of 423 children aged 6–8 years examined at baseline of The Physical Activity and Nutrition in Children (PANIC) Study. We assessed food consumption by food records and plasma FA composition by gas chromatography. We used linear regression models adjusted for age, sex, physical activity and total energy intake to analyze the associations. A higher consumption of vegetable oil-based margarine (fat 60–80 %) was associated with a higher proportion of linoleic and α-linolenic acids in plasma CE and PL. A higher consumption of high-fiber grain products was related to a lower proportion of oleic acid in CE and PL. The consumption of candy was directly associated with the proportion of palmitoleic and oleic acid in plasma CE. The consumption of vegetable oil-based margarine was inversely associated with estimated stearoyl-CoA-desaturase activity in plasma CE and PL and the consumption of candy was directly related to it in plasma CE. The results of our study suggest that plasma FA composition is not only a biomarker for dietary fat quality but also reflects the consumption of high-fiber grain products and foods high in sugar among children. 相似文献
77.
Lars-Åke Appelqvist 《Journal of the American Oil Chemists' Society》1972,49(3):151-152
By silicic acid column separation small quantities of glycolipid-rich fractions have been isolated from commercial Swedish
rapeseed “lecithin.” Major components in these fractions are monogalactosyl diglyceride and digalactosyl diglyceride which
have been identified by Rf on thin layer chromatography specific color reactions and IR spectrometry. The fatty acid patterns of the galactolipids are
different from those of the major phospholipids of the same product, with less of palmitic and oleic and considerably more
of linolenic acid. 相似文献
78.
In this paper we present a systematic approach for taking into account the resulting CO2 emissions reductions from investments in process integration measures in industry when optimizing those investments under economic uncertainty. The fact that many of the uncertainties affecting investment decisions are related to future CO2 emissions targets and policies implies that a method for optimizing not only economic criteria, but also greenhouse gas reductions, will provide better information to base the decisions on, and possibly also result in a more robust solution. In the proposed approach we apply a model for optimization of decisions on energy efficiency investments under uncertainty and regard the decision problem as a multiobjective programming problem. The method is applied to a case of energy efficiency investments at a chemical pulp mill. The case study is used to illustrate that the proposed method provides a good framework for decision-making about energy efficiency measures when considerations regarding greenhouse gas reductions influence the decisions. We show that by setting up the problem as a multiobjective programming model and at the same time incorporating uncertainties, the trade-off between economic and environmental criteria is clearly illustrated. 相似文献
79.
Mapping the thermal distribution within a silica preform tube using regenerated fibre Bragg gratings
Mattias L. Åslund John Canning Albert Canagasabey Roberson Assis de Oliveira Yang Liu Kevin Cook Gang-Ding Peng 《International Journal of Heat and Mass Transfer》2012,55(11-12):3288-3294
The temperature profile of the reaction zone inside the silica substrate tube during thermal heating with a H2/O2 flame under conditions identical to those used in the fabrication of optical fibre preforms using a modified chemical vapour deposition lathe has been characterised with ultra-high temperature stable regenerated optical fibre Bragg gratings. Experimental and theoretical results indicate a significant drop in temperature – up to several hundred degrees – across the tube wall from outside to inside. These results are in contradiction with the broadly accepted assumption that there is no significant thermal gradient across the tube itself. An array of regenerated gratings demonstrates that optical fibre grating based sensing can achieve distributed ultra-high temperature mapping and monitoring in harsh environments. 相似文献
80.
Exploration of the two‐photon excitation spectrum of fluorescent dyes at wavelengths below the range of the Ti:Sapphire laser 下载免费PDF全文
J. TRÄGÅRDH G. ROBB R. AMOR W.B. AMOS J. DEMPSTER G. McCONNELL 《Journal of microscopy》2015,259(3):210-218
We have studied the wavelength dependence of the two‐photon excitation efficiency for a number of common UV excitable fluorescent dyes; the nuclear stains DAPI, Hoechst and SYTOX Green, chitin‐ and cellulose‐staining dye Calcofluor White and Alexa Fluor 350, in the visible and near‐infrared wavelength range (540–800 nm). For several of the dyes, we observe a substantial increase in the fluorescence emission intensity for shorter excitation wavelengths than the 680 nm which is the shortest wavelength usually available for two‐photon microscopy. We also find that although the rate of photo‐bleaching increases at shorter wavelengths, it is still possible to acquire many images with higher fluorescence intensity. This is particularly useful for applications where the aim is to image the structure, rather than monitoring changes in emission intensity over extended periods of time. We measure the excitation spectrum when the dyes are used to stain biological specimens to get a more accurate representation of the spectrum of the dye in a cell environment as compared to solution‐based measurements. 相似文献