全文获取类型
收费全文 | 336篇 |
免费 | 47篇 |
专业分类
化学工业 | 195篇 |
金属工艺 | 3篇 |
机械仪表 | 8篇 |
建筑科学 | 9篇 |
能源动力 | 5篇 |
轻工业 | 66篇 |
水利工程 | 2篇 |
石油天然气 | 5篇 |
无线电 | 17篇 |
一般工业技术 | 36篇 |
冶金工业 | 17篇 |
自动化技术 | 20篇 |
出版年
2023年 | 3篇 |
2022年 | 41篇 |
2021年 | 51篇 |
2020年 | 14篇 |
2019年 | 7篇 |
2018年 | 14篇 |
2017年 | 21篇 |
2016年 | 17篇 |
2015年 | 14篇 |
2014年 | 21篇 |
2013年 | 14篇 |
2012年 | 17篇 |
2011年 | 32篇 |
2010年 | 14篇 |
2009年 | 15篇 |
2008年 | 12篇 |
2007年 | 10篇 |
2006年 | 12篇 |
2005年 | 5篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1976年 | 2篇 |
排序方式: 共有383条查询结果,搜索用时 15 毫秒
121.
Vincenzo?VitaglianoEmail author Dario?Castagnolo Giuseppe?De?Chiara Pier?Luigi?Vitagliano Dario?De?Luca Marianna?Pannico Maria?Tommasone Maurizio?Villani Paolo?Zampino 《Microgravity science and technology》2003,14(4):21-26
The behaviour of a diffusion boundary between distilled water and a 1% sodium chloride solution during a parabolic flight
has been observed. The presence of a few percent of Earth gravity pulses during the micro gravity conditions is sufficient
to largely perturb the diffusion boundary that stabilises again during the subsequent normal gravity conditions present inside
the aircraft at the end of each parabola. A numerical simulation of the boundary behaviour agrees with the experimental observation.
Student flying team 相似文献
122.
The moment analysis of elution peak profiles based on new moment equations provides information on the mass-transfer characteristics of C(18)-silica monolithic columns. The flow rate dependence of the HETP data was analyzed using the generalized van Deemter equation, after correction of these data by subtraction of the external mass-transfer contribution to band broadening. Kinetic parameters and diffusion coefficients related to the mass-transfer processes in monolithic columns were derived by taking advantage of the different flow velocity dependence of their contributions to band broadening. At high flow rates, axial dispersion and diffusive migration across the monolithic C(18)-silica skeleton contribute much to band broadening, suggesting that it remains important to reduce the influence of eddy diffusion and the mass-transfer resistance in the stationary phase to achieve fast separations and a high efficiency. Surface diffusion plays a predominant role for molecular migration in the monolithic stationary phase. Although the value of the surface diffusion coefficient (D(s)) depends on an estimate of the external mass-transfer coefficient, D(s) values of the order of 10(-7) cm(2) s(-1) were calculated for the first time for the C(18)-silica monolithic skeleton. The value of D(s) decreases with increasing retention of sample compounds. Analysis of a kind of time constant calculated from D(s) suggests that the "chromatographic corresponding particle size" is approximately 4 microm for the C(18)-silica monolithic stationary phase used in this study. The accuracy of the D(s) values determined was discussed. 相似文献
123.
Marianna Martinello Nicoletta Dainese Chiara Manzinello Alice Borin Albino Gallina 《Food Additives and Contaminants: Part B: Surveillance Communications》2016,9(3):198-202
Lead is a naturally occurring element but largely originating from human activities. Food is the major source of exposure to lead for humans and the publication of a scientific opinion from the European Food Safety Authority on the risks to human health related to the presence of lead in foodstuffs, led European Union to establish more restrictive limits for this contaminant in food from 1 January 2016. In particular, a maximum level of 0.10 mg kg?1 was established for honey. The retrospective evaluation of 995 honey samples analysed since 2005, revealed a progressive reduction in the concentration of lead, with a mean value of 0.045 mg kg?1 in 2015. Total 1.5% of honeys analysed in 2015 exceeded the maximum lead level and therefore will no longer be marketable. Interested beekeepers should clarify the causes of honey contamination and adopt corrective actions to keep their honey production within the legal levels of lead. 相似文献
124.
Marianna Brunetti 《Housing Studies》2017,32(2):168-185
The use of a second home may result in different outcomes for households, ranging from financial profit and holiday use to uses that are clearly unprofitable. We contribute to the literature on second homes by exploring the case of second homes that are not let out, representing the least profitable outcome from an economic viewpoint. The empirical investigation relies on the 2002–2012 Bank of Italy Survey on Household Income and Wealth (SHIW), which also provides extensive information on property, including the actual use. Our results highlight: a gender gap, whereby the unprofitable use of second homes tends to be more clearly associated with male decision-makers; a lack of association with the economic characteristics of the household; and a strong association with the specific characteristics of the property, with inherited property more likely to be used unprofitably. In addition to casting doubt on the effectiveness of second homes as an investment vehicle, our results may have important policy or regulatory implications for housing and rental markets. 相似文献
125.
Maria Francesca Santolla Marianna Talia Marcello Maggiolini 《International journal of molecular sciences》2021,22(9)
Triple-negative breast cancer (TNBC) is an aggressive breast tumor subtype characterized by poor clinical outcome. In recent years, numerous advancements have been made to better understand the biological landscape of TNBC, though appropriate targets still remain to be determined. In the present study, we have determined that the expression levels of FGF2 and S100A4 are higher in TNBC with respect to non-TNBC patients when analyzing “The Invasive Breast Cancer Cohort of The Cancer Genome Atlas” (TCGA) dataset. In addition, we have found that the gene expression of FGF2 is positively correlated with S100A4 in TNBC samples. Performing quantitative PCR, Western blot, CRISPR/Cas9 genome editing, promoter studies, immunofluorescence analysis, subcellular fractionation studies, and ChIP assays, we have also demonstrated that FGF2 induces in TNBC cells the upregulation and secretion of S100A4 via FGFR1, along with the ERK1/2–AKT–c-Rel transduction signaling. Using conditioned medium from TNBC cells stimulated with FGF2, we have also ascertained that the paracrine activation of the S100A4/RAGE pathway triggers angiogenic effects in vascular endothelial cells (HUVECs) and promotes the migration of cancer-associated fibroblasts (CAFs). Collectively, our data provide novel insights into the action of the FGF2/FGFR1 axis through S100A4 toward stimulatory effects elicited in TNBC cells. 相似文献
126.
Judit Bnyai Marco Maccaferri Lszl Lng Marianna Mayer Viola Tth Mnika Cspl Magda Pl Klra Mszros Gyula Vida 《International journal of molecular sciences》2021,22(4)
A detailed study was made of changes in the plant development, morphology, physiology and yield biology of near-isogenic lines of spring durum wheat sown in the field with different plant densities in two consecutive years (2013–2014). An analysis was made of the drought tolerance of isogenic lines selected for yield QTLs (QYld.idw-2B and QYld.idw-3B), and the presence of QTL effects was examined in spring sowings. Comparisons were made of the traits of the isogenic pairs QYld.idw-3B++ and QYld.idw-3B−− both within and between the pairs. Changes in the polyamine content, antioxidant enzyme activity, chlorophyll content of the flag leaf and the normalized difference vegetation index (NDVI) of the plot were monitored in response to drought stress, and the relationship between these components and the yield was analyzed. In the case of moderate stress, differences between the NIL++ and NIL−− pairs appeared in the early dough stage, indicating that the QYld.idw-3B++ QTL region was able to maintain photosynthetic activity for a longer period, resulting in greater grain number and grain weight at the end of the growing period. The chlorophyll content of the flag leaf in phenophases Z77 and Z83 was significantly correlated with the grain number and grain weight of the main spike. The grain yield was greatly influenced by the treatment, while the genotype had a significant effect on the thousand-kernel weight and on the grain number and grain weight of the main spike. When the lines were compared in the non-irrigated treatment, significantly more grains and significantly higher grain weight were observed in the main spike in NIL++ lines, confirming the theory that the higher yields of the QYld.idw-3B++ lines when sown in spring and exposed to drought stress could be attributed to the positive effect of the “Kofa” QTL on chromosome 3B. 相似文献
127.
Marianna Filandri 《Housing Studies》2014,29(7):977-993
On the basis of European Survey on Income and Living Conditions (EU-SILC) data, this paper conducts a comparative analysis of housing conditions in different European countries by focusing on social class. The variance in housing conditions by social class could provide further insights about the divergence/convergence hypotheses stemming from the comparative analysis of living conditions of European countries. To support this claim, two main dimensions of housing inequality will be identified: tenure and housing well-being. A micro-level data analysis was performed, in order to take account of individual and family costs of access and maintenance of ownership in settings and in periods (such as the present day) of rising housing prices and income resources that decrease in terms of amount and stability. The aim is thus to demonstrate that, despite the difference in well-being in Europe between owners and non-owners (on the average the firsts are better off), homeowners cannot be regarded as a privileged category per se. 相似文献
128.
Gabriel Biener Michael R. Stoneman Gheorghe Acbas Jessica D. Holz Marianna Orlova Liudmila Komarova Sergei Kuchin Valeric? Raicu 《International journal of molecular sciences》2014,15(1):261-276
Multiphoton micro-spectroscopy, employing diffraction optics and electron-multiplying CCD (EMCCD) cameras, is a suitable method for determining protein complex stoichiometry, quaternary structure, and spatial distribution in living cells using Förster resonance energy transfer (FRET) imaging. The method provides highly resolved spectra of molecules or molecular complexes at each image pixel, and it does so on a timescale shorter than that of molecular diffusion, which scrambles the spectral information. Acquisition of an entire spectrally resolved image, however, is slower than that of broad-bandwidth microscopes because it takes longer times to collect the same number of photons at each emission wavelength as in a broad bandwidth. Here, we demonstrate an optical micro-spectroscopic scheme that employs a laser beam shaped into a line to excite in parallel multiple sample voxels. The method presents dramatically increased sensitivity and/or acquisition speed and, at the same time, has excellent spatial and spectral resolution, similar to point-scan configurations. When applied to FRET imaging using an oligomeric FRET construct expressed in living cells and consisting of a FRET acceptor linked to three donors, the technique based on line-shaped excitation provides higher accuracy compared to the point-scan approach, and it reduces artifacts caused by photobleaching and other undesired photophysical effects. 相似文献
129.
130.
Effect of extrusion conditions on iron stability and physical and textural properties of corn snacks enriched with soybean ferritin
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)
Agnieszka Makowska Magdalena Zielińska‐Dawidziak Przemysław Niedzielski Michał Michalak 《International Journal of Food Science & Technology》2018,53(2):296-303
Soybean sprouts cultured in 20 mm FeSO4 were introduced into corn snacks (1.75–3.50%) to supplement iron. The effect of extrusion process on the ferritin iron stability and on product quality was studied. Iron stability in these fortified snacks depended mainly on feed moisture levels, with the best results seen when the feed moisture and temperature were 12% and 110 °C, respectively. Lower feed moisture was beneficial to hardness, expansion ratio and bulk density, while lower temperature increased snack hardness and density, while worsening the expansion ratio. The snacks’ water absorption was strongly and directly dependent on the temperature, while their solubility mainly depended inversely on feed moisture. All of the variables tested altered the colour of the snacks. The conditions that were best for producing the ferritin‐fortified snacks – 12% feed moisture, and temperature equal than or less to 140 °C – may yield a product with the desired quality features. 相似文献