首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1057篇
  免费   58篇
  国内免费   1篇
电工技术   17篇
化学工业   118篇
金属工艺   5篇
机械仪表   8篇
建筑科学   28篇
矿业工程   2篇
能源动力   14篇
轻工业   220篇
水利工程   5篇
石油天然气   1篇
无线电   135篇
一般工业技术   163篇
冶金工业   336篇
原子能技术   8篇
自动化技术   56篇
  2023年   5篇
  2022年   16篇
  2021年   30篇
  2020年   27篇
  2019年   22篇
  2018年   18篇
  2017年   20篇
  2016年   23篇
  2015年   15篇
  2014年   24篇
  2013年   24篇
  2012年   31篇
  2011年   40篇
  2010年   33篇
  2009年   25篇
  2008年   39篇
  2007年   38篇
  2006年   41篇
  2005年   27篇
  2004年   26篇
  2003年   24篇
  2002年   16篇
  2001年   12篇
  2000年   19篇
  1999年   23篇
  1998年   100篇
  1997年   68篇
  1996年   58篇
  1995年   26篇
  1994年   26篇
  1993年   20篇
  1992年   21篇
  1991年   17篇
  1990年   11篇
  1989年   18篇
  1988年   14篇
  1987年   6篇
  1986年   8篇
  1985年   6篇
  1984年   8篇
  1983年   5篇
  1982年   5篇
  1981年   4篇
  1980年   9篇
  1979年   7篇
  1977年   8篇
  1976年   13篇
  1975年   5篇
  1974年   7篇
  1973年   4篇
排序方式: 共有1116条查询结果,搜索用时 15 毫秒
31.
32.
Nonthermal plasma (NTP) is defined in terms of partly ionised gas which overall temperature is quite low because the stored energy is mostly in free electrons. Applications of NTP have been expanded to new areas of food applications such as the microbial inactivation and also the elimination of pesticide and toxic chemical residues in food such as fruits and vegetables while nutritional content and key characteristics are still preserved. Plasma treatment has successfully decreased the concentrations of pesticides by about 45‐71%. In this article, NTP technologies as well as investigations about applying of NTP for removing pesticide residues and improving microbial safety in fresh produce are described. Potential applications of NTP in food processing together with some of their challenges and limitations are also discussed.  相似文献   
33.
Extracellular mechanical cues have been shown to have a profound effect on osteogenic cell behaviour. However, it is not known precisely how these cues alter intracellular mechanics to initiate changes in cell behaviour. In this study, a combination of in vitro culture of MC3T3-E1 cells and finite-element modelling was used to investigate the effects of passive differences in substrate stiffness on intracellular mechanics. Cells on collagen-based substrates were classified based on the presence of cell processes and the dimensions of various cellular features were quantified. Focal adhesion (FA) density was quantified from immunohistochemical staining, while cell and substrate stiffnesses were measured using a live-cell atomic force microscope. Computational models of cell morphologies were developed using an applied contraction of the cell body to simulate active cell contraction. The results showed that FA density is directly related to cell morphology, while the effect of substrate stiffness on internal cell tension was modulated by both cell morphology and FA density, as investigated by varying the number of adhesion sites present in each morphological model. We propose that the cells desire to achieve a homeostatic stress state may play a role in osteogenic cell differentiation in response to extracellular mechanical cues.  相似文献   
34.
35.
The evolution of oxidative and structural characteristics of proteins, especially lipid transfer protein 1 (LTP1), in beer during forced-ageing was examined. The oxidative characteristics of beer and proteins were evaluated by DPPH radical scavenging activity and ABTS radical cation scavenging activity. Results showed that the levels of proteins, thiols, LTP1 and antioxidant activity decreased gradually. This was accompanied by the degradation of macromolecular proteins in beer during forced-ageing. Results from circular dichroism (CD), Fourier-transform infrared spectroscopy (FTIR), surface hydrophobicity (S0) and ζ-potential further indicated that the secondary and tertiary structure of LTP1 changed drastically during forced-ageing, with the reduction of the S0, α-helix and β-sheet contents and the increase in negative ζ-potential and random coil. Thus, the proteins, especially LTP1, might play important roles in maintaining oxidative stability of beer.  相似文献   
36.
37.
A geodatabase of tidal constituents is developed to present the regional assessment of tidal stream power resource in the USA. Tidal currents are numerically modeled with the Regional Ocean Modeling System (ROMS) and calibrated with the available measurements of tidal current speeds and water level surfaces. The performance of the numerical model in predicting the tidal currents and water levels is assessed by an independent validation. The geodatabase is published on a public domain via a spatial database engine with interactive tools to select, query and download the data. Regions with the maximum average kinetic power density exceeding 500 W/m2 (corresponding to a current speed of ~1 m/s), total surface area larger than 0.5 km2 and depth greater than 5 m are defined as hotspots and documented. The regional assessment indicates that the state of Alaska (AK) has the largest number of locations with considerably high kinetic power density, followed by, Maine (ME), Washington (WA), Oregon (OR), California (CA), New Hampshire (NH), Massachusetts (MA), New York (NY), New Jersey (NJ), North and South Carolina (NC, SC), Georgia (GA), and Florida (FL).  相似文献   
38.
This review presents the state‐of‐the‐art concerning the application of natural and artificial high‐intensity sweeteners, fructans and bulking agents such as polyols as sugar replacers in sweet‐baked goods and their effects on product characteristics. The recent much publicised attention given to weight gain of the population and its consequences on the occurrence of diet‐related diseases in developed countries has influenced the food manufacturers attempts to provide the consumer with reduced energy products. The replacement of sucrose in sweet bakery products by alternative natural or artificial sweeteners can be a challenging issue. Sucrose as a main ingredient in sweet bakery products contributes, aside from providing sweetness, to numerous processing and product characteristics. Intense sweeteners have a high sweetness compared with sucrose but lack in their contribution to the body of the product, whereas the replacement of sucrose with bulking sweeteners may result in products with a similar body but a lack in taste and flavour.  相似文献   
39.
Studies that estimate indoor aeroallergen exposure typically measure a pre‐selected limited range of allergens. In this study, inhalable aeroallergen particles were quantified using the halogen immunoassay (HIA) to determine the contribution of fungal and non‐fungal aeroallergens to total allergen exposure. Bioaerosols from 39 homes of fungal‐allergic subjects were sampled using inhalable fraction samplers and immunostained by HIA using resident subject's immunoglobulin E (IgE) to detect allergen‐laden particles. Fungal aerosols as well as particles carrying mite, cat, and cockroach allergens were identified and enumerated by HIA. Reservoir dust‐mite (Der p 1), cat (Fel d 1), and cockroach (Bla g 1) allergen concentrations were quantified by ELISA. Fungal particles that bound subject's IgE in the HIA were 1.7 (bedroom)‐ and 1.4 (living room)‐fold more concentrated than Der p 1, Fel d 1, and Bla g 1 allergen particles combined. Predominant fungal conidia that bound IgE were derived from common environmental genera including Cladosporium and other fungi that produce amerospores. Airborne mite, cat, and cockroach allergen particle counts were not associated with reservoir concentrations determined by ELISA. This study demonstrates that inhalable fungal aerosols are the predominant aeroallergen sources in Sydney homes and should be considered in future exposure assessments.  相似文献   
40.
Measurements of surface potential and surface conductivity in zinc oxide thin films in contact with eosin dye show that two regimes of spectral sensitization are involved under vacuum conditions. The dye molecules at the interface trap conduction electrons in the dark at a site close in energy to the dye ground state leading to a Schottky barrier. The return of the trapped electrons from the excited dye is held responsible for “thin layer” sensitization. With “thick” dye layers an additional contribution arises from charge transfer between the photoconducting solid dye and the zinc oxide substrate, in a direction which tends to equilibrate the Fermi levels in the two media, The decay of the ”thick layer” sensitized photoeffect is identical to the decay of the field effect in undyed zinc oxide films and is controlled by zinc oxide surface states.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号