全文获取类型
收费全文 | 1518篇 |
免费 | 12篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 102篇 |
金属工艺 | 23篇 |
机械仪表 | 17篇 |
建筑科学 | 64篇 |
矿业工程 | 1篇 |
能源动力 | 16篇 |
轻工业 | 132篇 |
水利工程 | 9篇 |
石油天然气 | 2篇 |
无线电 | 73篇 |
一般工业技术 | 68篇 |
冶金工业 | 919篇 |
原子能技术 | 7篇 |
自动化技术 | 87篇 |
出版年
2022年 | 8篇 |
2021年 | 9篇 |
2020年 | 5篇 |
2018年 | 4篇 |
2017年 | 9篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 15篇 |
2013年 | 39篇 |
2012年 | 23篇 |
2011年 | 31篇 |
2010年 | 32篇 |
2009年 | 28篇 |
2008年 | 32篇 |
2007年 | 31篇 |
2006年 | 34篇 |
2005年 | 18篇 |
2004年 | 23篇 |
2003年 | 18篇 |
2002年 | 12篇 |
2001年 | 9篇 |
2000年 | 16篇 |
1999年 | 44篇 |
1998年 | 270篇 |
1997年 | 170篇 |
1996年 | 101篇 |
1995年 | 71篇 |
1994年 | 59篇 |
1993年 | 76篇 |
1992年 | 23篇 |
1991年 | 20篇 |
1990年 | 19篇 |
1989年 | 26篇 |
1988年 | 21篇 |
1987年 | 17篇 |
1986年 | 12篇 |
1985年 | 11篇 |
1984年 | 5篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 14篇 |
1980年 | 11篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1977年 | 39篇 |
1976年 | 57篇 |
1975年 | 4篇 |
1974年 | 8篇 |
1968年 | 3篇 |
1955年 | 3篇 |
排序方式: 共有1530条查询结果,搜索用时 31 毫秒
901.
Philip Rasmussen Herman W. Barkema Steve Mason Eugene Beaulieu David C. Hall 《Journal of dairy science》2021,104(3):3123-3143
Johne's disease (JD), or paratuberculosis, is an infectious inflammatory disorder of the intestines primarily associated with domestic and wild ruminants including dairy cattle. The disease, caused by an infection with Mycobacterium avium subspecies paratuberculosis (MAP) bacteria, burdens both animals and producers through reduced milk production, premature culling, and reduced salvage values among MAP-infected animals. The economic losses associated with these burdens have been measured before, but not across a comprehensive selection of major dairy-producing regions within a single methodological framework. This study uses a Markov chain Monte Carlo approach to estimate the annual losses per cow within MAP-infected herds and the total regional losses due to JD by simulating the spread and economic impact of the disease with region-specific economic variables. It was estimated that approximately 1% of gross milk revenue, equivalent to US$33 per cow, is lost annually in MAP-infected dairy herds, with those losses primarily driven by reduced production and being higher in regions characterized by above-average farm-gate milk prices and production per cow. An estimated US$198 million is lost due to JD in dairy cattle in the United States annually, US$75 million in Germany, US$56 million in France, US$54 million in New Zealand, and between US$17 million and US$28 million in Canada, one of the smallest dairy-producing regions modeled. 相似文献
902.
Kan Wen Hao Huang Siyu Man Ziyan Handoko Wilson Chang Li Pahlevani Farshid Rasmussen Kim Sahajwalla Veena 《Metallurgical and Materials Transactions A》2020,51(5):2404-2410
Metallurgical and Materials Transactions A - Decarburization of steels during heat treatment is a major problem for wear applications and for thin structural components as it often results in... 相似文献
903.
Dependence of physiochemical,functional and textural properties of high‐resistant starch rice on endogenous nonstarch polysaccharides
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Xiuqiong Zhang Søren K. Rasmussen Xiaotong Jiang Wenjian Song Dianxing Wu Xiaoli Shu 《International Journal of Food Science & Technology》2018,53(4):1079-1086
To investigate the possibility of improving the quality of rice rich in resistant starch through operation of nonstarch polysaccharides, the high dietary fibre (7.24%) mutant cw and its wild‐type R7954 were selected to study the physiochemical characteristics of starch before and after removal of nonstarch polysaccharides. Results showed that hydrolysed or partially hydrolysed nonstarch polysaccharides in cw decreased the resistant starch content significantly, from 15.23% to 10.8%. Nonstarch polysaccharides had significant influences on the gelatinisation temperature, RVA parameters of R7954, but no significant influences on that of cw. For cw, removal of cellulose increased swelling power and adhesiveness, decreased the hardness significantly, from 0.3 to 0.23 N, while the resistant starch content was still as high as 13.72% and showed no significant difference from the wild type. This suggests that the influences of nonstarch polysaccharides on starch properties depend both on the type of rice and the nonstarch polysaccharides. Operation on nonstarch polysaccharides for obtaining rice with lower glycemic index is feasible, but operation on nonstarch polysaccharides may also be an alternative way of improving the palatability for rice high in resistant starch. 相似文献
904.
HyperNews is a prototype user interface to reading the articles coming in over the Unix network news. HyperNews automatically constructs hypertext links between articles which are part of a stream of articles commenting on each other, and it also constructs links to articles outside these streams if they are considered related to the current article according to a similarity rating based on an information retrieval formula. 相似文献
905.
906.
Berit B. Rasmussen Kai Wang Johan G. Karstoft Søren N. Skov Morten Køcks Christina Andersen Aneta Wierzbicka Joakim Pagels Peter B. Pedersen Marianne Glasius Merete Bilde 《Indoor air》2021,31(4):1084-1094
Emissions from candles are of concern for indoor air quality. In this work, five different types of pillar candles were burned under steady burn conditions in a new laboratory scale system for repeatable and controlled comparison of candle emissions (temperature ~25°C, relative humidity ~13%, O2 >18%, air exchange rate 1.9 h−1). Burn rate, particle number concentrations, mass concentrations, and mode diameters varied between candle types. Based on the results, the burning period was divided in two phases: initial (0–1 h) and stable (1–6 h). Burn rates were in the range 4.4–7.3 and 4.7–7.1 g/h during initial and stable phase, respectively. Relative particle number emissions, mode diameters, and mass concentrations were higher during the initial phase compared to the stable phase for a majority of the candles. We hypothesize that this is due to elevated emissions of wick additives upon ignition of the candle together with a slightly higher burn rate in the initial phase. Experiments at higher relative humidity (~40%) gave similar results with a tendency toward larger particle sizes at the higher relative humidity. Chemical composition with respect to inorganic salts was similar in the emitted particles (dry conditions) compared to the candlewicks, but with variations between different candles. 相似文献
907.
Gianluca Picariello Francesco Bonomi Stefania Iametti Patrizia Rasmussen Carolina Pepe Sergio Lilla Pasquale Ferranti 《Food chemistry》2011
In this study, the protein and peptide fractions of two commercial Italian barley malt beers, made with different processes by the same producer, have been analysed with a combined immunochemical and mass spectrometry approach. The “gluten” content of beer samples, measured with the R5 monoclonal antibody, was below the caution limit proposed by the Codex Alimentarius for gluten-free foods. The proteomic approach allowed to identify a 17 kDa avenin-like protein partially homologous to hordeins, that was particularly abundant in foam, in addition to the already reported barley albumins (Z4-barley and ns-LTPs) and to minor amounts of yeast glycolytic enzymes. No intact hordeins were detected, although fragments derived from γ3- and B-hordein were present. In consideration of the many implications of the protein/peptide pattern, these data provide useful information to improve quality and safety of beer. 相似文献
908.
Y. W. Kwon W. Y. Lee A. S. McGee D. C. Hart D. C. Loup E. A. Rasmussen 《Applied Composite Materials》2013,20(6):1321-1339
A study was undertaken to develop an analytical model that can predict how much reduction in Strain Energy Release Rate (SERR) can be achieved by repairing a cracked plate using a single-side bonded patch. The plate may be subjected to inplane or out-of-plane bending loading. Furthermore, the plate may be flat or curved in a cylindrical shape. The model helps to select patch material (i.e., elastic modulus of the material) and the appropriate patch size in order to reduce the SERR at the crack tip of the patched base plate. In other words, the analytical model can be utilized to select the patch material and patch dimensions required to achieve the desired SERR for a cracked base plate with known modulus, thickness, and crack size. The model is based on axial and bending stresses of the single-side strap joint configuration, which are related to the SERR at the crack tip of a plate with a single-side patch repair. In order to verify the analytical model, finite element analyses were conducted to determine stresses as well as SERR in many different patched plates. The numerical study confirmed the validity of the analytical model in predicting the reduction ratio of SERR resulting from the single-side patch repair. 相似文献
909.
Schäfer RB von der Ohe PC Rasmussen J Kefford BJ Beketov MA Schulz R Liess M 《Environmental science & technology》2012,46(9):5134-5142
We compiled data from eight field studies conducted between 1998 and 2010 in Europe, Siberia, and Australia to derive thresholds for the effects of pesticides on macroinvertebrate communities and the ecosystem function leaf breakdown. Dose-response models for the relationship of pesticide toxicity with the abundance of sensitive macroinvertebrate taxa showed significant differences to reference sites at 1/1000 to 1/10,000 of the median acute effect concentration (EC50) for Daphnia magna, depending on the model specification and whether forested upstream sections were present. Hence, the analysis revealed effects well below the threshold of 1/100 of the EC50 for D. magna incorporated in the European Union Uniform Principles (UP) for registration of single pesticides. Moreover, the abundances of sensitive macroinvertebrates in the communities were reduced by 27% to 61% at concentrations related to 1/100 of the EC50 for D. magna. The invertebrate leaf breakdown rate was positively linearly related to the abundance of pesticide-sensitive macroinvertebrate species in the communities, though only for two of the three countries examined. We argue that the low effect thresholds observed were not mainly because of an underestimation of field exposure or confounding factors. From the results gathered we derive that the UP threshold for single pesticides based on D. magna is not protective for field communities subject to multiple stressors, pesticide mixtures, and repeated exposures and that risk mitigation measures, such as forested landscape patches, can alleviate effects of pesticides. 相似文献
910.
X-ray absorption fine-structure (XAFS) spectroscopy, micro-X-ray fluorescence (μXRF), and micro-X-ray diffraction (μXRD) were used to determine the speciation of Pb in house dust samples from four Canadian urban homes having elevated Pb concentrations (>1000 mg Pb kg(-1)). Linear combination fitting of the XAFS data, supported by μXRF and μXRD, shows that Pb is complexed in a variety of molecular environments, associated with both the inorganic and organic fractions of the dust samples. The inorganic species of lead identified were as follows: Pb metal, Pb carbonate, Pb hydroxyl carbonate, Pb oxide, and Pb adsorbed to iron oxyhydroxides. Pb carbonate and/or Pb hydroxyl carbonate occurred in all four dust samples and accounted for 28 to 75% of total Pb. Pb citrate and Pb bound to humate were the organic species identified. The results of this study demonstrate the ability of XAFS to identify Pb speciation in house dust and show the potential to identify Pb sources from new homes versus older homes. Understanding Pb speciation and how it influences bioaccessibility is important for human health risk assessment and risk management decisions which aim to improve indoor environmental health. 相似文献