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71.
Mats E. HØvin Dag T. Wisland Jan T. Marienborg Tor S. Lande Yngvar Berg 《Analog Integrated Circuits and Signal Processing》2001,26(1):75-82
In this paper, we show that the first-order frequency delta–sigma modulator is equivalent to a traditional delta–sigma modulator with respect to pattern noise. We further propose two techniques for reducing the effect of pattern noise. The first technique is based on time-domain dithering which is implemented by adding white phase noise to the FM signal. The second technique is based on locating the narrow dynamic range that may be in this kind of modulators, in a pattern noise valley. This technique can utilize pattern noise to make the modulator provide significantly higher digital resolution than the white quantization noise model predicts. Finally, the theory is verified by measurements. 相似文献
72.
Østlie HM Eliassen L Florvaag A Skeie S 《International journal of food microbiology》2004,94(3):287-299
Microbiological sampling of Norvegia cheese from three cheese factories was done during ripening. The evolution of aerobic mesophilic bacteria, lactococci, lactobacilli, enterococci, presumptive leuconostoc and pediococci was investigated after 30, 90, 180 and 270 days of ripening. Isolates (135) of non-starter lactic acid bacteria (NSLAB) from nine Norvegia cheeses after 90, 180 and 270 days of ripening were examined. The isolates were tested by physiological and biochemical assays, species-specific PCR and 16S rDNA sequencing. After 90 days of ripening Leuconostoc spp., most probably from the starter, and the NSLAB specie Lactobacillus paracasei dominated among the isolates, however, after longer ripening Lb. paracasei dominated. The development and evolution of the microflora in Norvegia varied according to dairy and ripening time. 相似文献
73.
Karin Rosenkilde Laursen Berit Brøndum Rasmussen Bernadette Rosati Vibeke Heitmann Gutzke Kirsten Østergaard Peter Ravn Søren Kenneth Kjærgaard Merete Bilde Marianne Glasius Torben Sigsgaard 《Indoor air》2021,31(6):1993-2007
Particulate matter is linked to adverse health effects, however, little is known about health effects of particles emitted from typical indoor sources. We examined acute health effects of short-term exposure to emissions from cooking and candles among asthmatics. In a randomized controlled double-blinded crossover study, 36 young non-smoking asthmatics attended three exposure sessions lasting 5 h: (a) air mixed with emissions from cooking (fine particle mass concentration): (PM2.5: 96.1 μg/m3), (b) air mixed with emissions from candles (PM2.5: 89.8 μg/m3), and c) clean filtered air (PM2.5: 5.8 μg/m3). Health effects (spirometry, fractional exhaled Nitric Oxide [FeNO], nasal volume and self-reported symptoms) were evaluated before exposure start, then 5 and 24 h after. During exposures volatile organic compounds (VOCs), particle size distributions, number concentrations and optical properties were measured. Generally, no statistically significant changes were observed in spirometry, FeNO, or nasal volume comparing cooking and candle exposures to clean air. In males, nasal volume and FeNO decreased after exposure to cooking and candles, respectively. Participants reported additional and more pronounced symptoms during exposure to cooking and candles compared to clean air. The results indicate that emissions from cooking and candles exert mild inflammation in asthmatic males and decrease comfort among asthmatic males and females. 相似文献
74.
Jørn A. Holme Elisabeth Øya Anani K. J. Afanou Johan Øvrevik Wijnand Eduard 《Indoor air》2020,30(4):662-681
A number of epidemiological studies find an association between indoor air dampness and respiratory health effects. This is often suggested to be linked to enhanced mold growth. However, the role of mold is obviously difficult to disentangle from other dampness-related exposure including microbes as well as non-biological particles and chemical pollutants. The association may partly be due to visible mycelial growth and a characteristic musty smell of mold. Thus, the potential role of mold exposure should be further explored by evaluating information from experimental studies elucidating possible mechanistic links. Such studies show that exposure to spores and hyphal fragments may act as allergens and pro-inflammatory mediators and that they may damage airways by the production of toxins, enzymes, and volatile organic compounds. In the present review, we hypothesize that continuous exposure to mold particles may result in chronic low-grade pro-inflammatory responses contributing to respiratory diseases. We summarize some of the main methods for detection and characterization of fungal aerosols and highlight in vitro research elucidating how molds may induce toxicity and pro-inflammatory reactions in human cell models relevant for airway exposure. Data suggest that the fraction of fungal hyphal fragments in indoor air is much higher than that of airborne spores, and the hyphal fragments often have a higher pro-inflammatory potential. Thus, hyphal fragments of prevalent mold species with strong pro-inflammatory potential may be particularly relevant candidates for respiratory diseases associated with damp/mold-contaminated indoor air. Future studies linking of indoor air dampness with health effects should assess the toxicity and pro-inflammatory potential of indoor air particulate matter and combined this information with a better characterization of biological components including hyphal fragments from both pathogenic and non-pathogenic mold species. Such studies may increase our understanding of the potential role of mold exposure. 相似文献
75.
Benthic animal production was studied in a weir basin area of western Norway in 1984, eleven years after construction of the basin and eight years after the first benthic study. Compared to estimates from 1976, a marked change in production and species composition had occurred. Benthic animal production at two stations inside the basin was 199 and 169 KJ m?2 yr?1, an increase of 440 and 270 per cent respectively compared to 1976. In a riffle upstream of the basin, the production estimate was 50 KJ m?2 yr?1, a decrease of 40 per cent since 1976. Chironomids formed the main contribution to the increased production in the weir basin, mainly through increased abundance of larger species like Stictochironomus pictulus and Micropsectra spp. Also other species more adapted to lentic water, like the ephemeropterans Siphlonurus aestivalis and Ameletus inopinatus, showed increased density. The fauna succession and increased production in the weir basin was mainly due to improved habitats and food conditions, as the amount of organic sediments had increased since the first production study. 相似文献
76.
Øyvind Bjørke 《Computers & Graphics》1985,9(2):165-169
Correct structuring and representation of production management-information will make the decision process more efficient in a factory. Graphic representation of survey data and comparisons are often very useful, although one loses some accuracy, compared with tables. The use of colours in this context makes the charts easier to understand, and more information may be shown without making the chart unclear. These facts have made the interactive graphic techniques useful for planning and resource allocation purposes. The result has been installed in industry.The study also presents a new method for automatic quality supervision. A detailed analysis of workpieces and products from mechanical industry is carried out.The method is a substitute for visual inspection as well as manual measurements: Missing holes, broken corners, and undesired material are detected. Important details are measured. There are individual tolerances on all measures. Parts that do not meet the requirements are rejected.The supervision program is easily changed, and the method is therefore suitable for small series production. The picture from a special TV camera is the basis for the quality supervision, which is of the noncontact type. 相似文献
77.
Usability and user experience (UX) methods come from academic environments, where industrial conditions such as time and resources are not of prime importance. Furthermore, usability and UX methods originate from a time when almost all software developments followed a traditional approach, such as the waterfall model. These two facts entail that existing methods often are too resource demanding and complex to apply directly into today’s agile, industrial environments. In this paper we make the claim that methods must be updated and tailored in order to be applicable within the agile, industrial development framework of today. We pursue a solution to simplify well-known methods and to train software developers to perform the UX work. To do this, three methods are modified via an iterative process together with the development of supporting materials. Software developers in three companies are trained in the methods to assess the approach. We find that it indeed is feasible to update and tailor existing usability and UX methods to fit into an agile, industrial environment. Furthermore, we show that it is possible to train developers to perform the usability and UX methods via one-day, in-situ sessions using an ‘instructor’-teaching approach. The training is based on hands-on exercises and real-life tasks. This further boosts the developers’ confidence in performing UX work and promises a better consideration of UX in the development phases. We evaluate our approach through observations of the developers performing the UX tasks on their own at a later point in time. 相似文献
78.
A long-term seal- and cod-liver-oil supplementation in hypercholesterolemic subjects 总被引:1,自引:0,他引:1
In this long-term study, we wanted to explore the effect of dietary supplementation of seal oil (SO) as compared cod-liver
oil (CLO) on subjects with moderate hypercholesterolemia. The test parameters included fatty acid composition in serum, blood
lipids, platelet aggregation, and the activity of blood monocytes. After a run-in period of 6 mon, 120 clinically healthy
hypercholesterolemic (7.0–9.5 mmol/L; 270–366 mg/dL) subjects were randomly selected to consume either 15 mL of SO or CLO
daily for 14 mon followed by a 4-mon wash-out period. A third group was not given any dietary supplement (control). Consumption
of marine oils (SO and CLO) changed the fatty acid composition of serum significantly. Maximal levels were achieved after
10 mon. No further changes were seen after 14 mon. A wash-out period of 4 mon hardly altered the level of n−3 fatty acids
in serum. Addition of SO gave 30% higher level of eicosapentaenoic acid, as compared to CLO. Subjects taking SO or CLO had
lower whole-blood platelet aggregation than the control group. Neither SO nor CLO had any effects on the levels of serum total
cholesterol, high-density lipoprotein cholesterol, postprandial triacylglycerol, apolipoproteins A1 and B100, lipoprotein
(a), monocyte function expressed as monocyte-derived tissue factor expression, and tumor necrosis factor. 相似文献
79.
The appearance of visible crazes and the growth of crazes during creep in tension for multiphase acrylic systems have been studied. The polymeric materials, commonly applied in bioengineering, were processed by polymerization of a mixture of liquid methacrylate monomers and poly(methyl methacrylate) (PMMA) powder. The specimens were made with various ratios of methyl methacrylate (MMA) and the crosslinking agent ethyleneglycol dimethacrylate (EGDMA) in the monomer liquid. Two different processing conditions were used, i.e. heat-polymerization at 100°C and auto-polymerization at 45°C. The critical strain value c for the appearance of visible crazes under the influence of a constant tensile stress increased with increasing quantity of EGDMA in the heat-polymerized materials, and the crazes were equally distributed at the surface of the materials observed. In the cross-linked auto-polymerized materials, crazing started in the spherical polymer beads from the PMMA prepolymer powder, and c was independemt of the quantity of EGDMA. In the auto-polymerized materials crazes in a necked region opened up to form diamond-shaped cavities. Fracture started with a cavity that expanded through both matrix and polymer beads. The heat-polymerized materials failed in a brittle manner, whereas the auto-polymerized materials failed in a ductile manner. 相似文献
80.
Louise Albertsen Dr. Søren Østergaard Dr. Johan F. Paulsson Dr. Jens Chr. Norrild Prof. Kristian Strømgaard 《ChemMedChem》2013,8(9):1505-1513
The gut hormone peptide YY (PYY) is postprandially secreted from enteroendocrine L cells and is involved in the regulation of energy homeostasis. The N‐terminal truncated version PYY(3–36) decreases food intake and has potential as an anti‐obesity agent. The anorectic effect of PYY(3–36) is mediated through Y2 receptors in the hypothalamus, vagus, and brainstem regions, and it is well known that the C‐terminal tetrapeptide sequence of PYY(3–36) is crucial for Y2 receptor activation. The aim of this work was to develop a semisynthetic methodology for the generation of a library of C‐terminally modified PYY(3–36) analogues. By using an intein‐based expression system, PYY(3–29) was generated as a C‐terminal peptide α‐thioester. Heptapeptides bearing an N‐terminal cysteine and modifications at one of the four C‐terminal positions were synthesized in a 96‐well plate by parallel solid‐phase synthesis. In the plate format, an array of [Ala30]PYY(3–36) analogues were generated by ligation, desulfurization, and subsequent solid‐phase extraction. The generated analogues, in which either Arg33, Gln34, Arg35, or Tyr36 had been substituted with proteinogenic or non‐proteinogenic amino acids, were tested in a functional Y2 receptor assay. Generally, substitutions of Tyr36 were better tolerated than modifications of Arg33, Gln34, and Arg35. Two analogues showed significantly improved Y2 receptor selectivity; therefore, these results could be used to design new drug candidates for the treatment of obesity. 相似文献