全文获取类型
收费全文 | 388篇 |
免费 | 21篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 196篇 |
金属工艺 | 11篇 |
机械仪表 | 12篇 |
建筑科学 | 12篇 |
矿业工程 | 1篇 |
能源动力 | 5篇 |
轻工业 | 64篇 |
石油天然气 | 4篇 |
无线电 | 9篇 |
一般工业技术 | 42篇 |
冶金工业 | 6篇 |
原子能技术 | 1篇 |
自动化技术 | 36篇 |
出版年
2023年 | 6篇 |
2022年 | 30篇 |
2021年 | 29篇 |
2020年 | 11篇 |
2019年 | 10篇 |
2018年 | 13篇 |
2017年 | 11篇 |
2016年 | 11篇 |
2015年 | 9篇 |
2014年 | 13篇 |
2013年 | 22篇 |
2012年 | 17篇 |
2011年 | 33篇 |
2010年 | 16篇 |
2009年 | 12篇 |
2008年 | 20篇 |
2007年 | 15篇 |
2006年 | 10篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 9篇 |
2002年 | 9篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1989年 | 1篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有409条查询结果,搜索用时 0 毫秒
31.
Irena Roterman Katarzyna Stapor Krzysztof Gdek Tomasz Gubaa Piotr Nowakowski Piotr Fabian Leszek Konieczny 《International journal of molecular sciences》2021,22(24)
Currently available analyses of amyloid proteins reveal the necessity of the existence of radical structural changes in amyloid transformation processes. The analysis carried out in this paper based on the model called fuzzy oil drop (FOD) and its modified form (FOD-M) allows quantifying the role of the environment, particularly including the aquatic environment. The starting point and basis for the present presentation is the statement about the presence of two fundamentally different methods of organizing polypeptides into ordered conformations—globular proteins and amyloids. The present study shows the source of the differences between these two paths resulting from the specificity of the external force field coming from the environment, including the aquatic and hydrophobic one. The water environment expressed in the fuzzy oil drop model using the 3D Gauss function directs the folding process towards the construction of a micelle-like system with a hydrophobic core in the central part and the exposure of polarity on the surface. The hydrophobicity distribution of membrane proteins has the opposite characteristic: Exposure of hydrophobicity at the surface of the membrane protein with an often polar center (as in the case of ion channels) is expected. The structure of most proteins is influenced by a more or less modified force field generated by water through the appropriate presence of a non-polar (membrane-like) environment. The determination of the proportion of a factor different from polar water enables the assessment of the protein status by indicating factors favoring the structure it represents. 相似文献
32.
The examination of the structure of cokes obtained from extracts separated from preheated vitrites of coking coals by progressive and continuous extraction with chloroform was carried out. The structural ordering (interplanar spacing and crystallite dimensions) of the cokes depends on the rank of the parent vitrites but it does not depend on the degree of extraction. The occurrence of optical anisotropy in cokes from the extracts is connected with both the rank of the parent vitrite and the degree of extraction. In the formation of the optical anisotropic structure during the carbonization of coking coal vitrites, the part of the extract which is of small size, which partially undergoes decomposition, is an important factor. 相似文献
33.
Jan Korbecki Klaudyna Kojder Patrycja Kapczuk Patrycja Kupnicka Barbara Gawroska-Szklarz Izabela Gutowska Dariusz Chlubek Irena Baranowska-Bosiacka 《International journal of molecular sciences》2021,22(2)
Hypoxia is an integral component of the tumor microenvironment. Either as chronic or cycling hypoxia, it exerts a similar effect on cancer processes by activating hypoxia-inducible factor-1 (HIF-1) and nuclear factor (NF-κB), with cycling hypoxia showing a stronger proinflammatory influence. One of the systems affected by hypoxia is the CXC chemokine system. This paper reviews all available information on hypoxia-induced changes in the expression of all CXC chemokines (CXCL1, CXCL2, CXCL3, CXCL4, CXCL5, CXCL6, CXCL7, CXCL8 (IL-8), CXCL9, CXCL10, CXCL11, CXCL12 (SDF-1), CXCL13, CXCL14, CXCL15, CXCL16, CXCL17) as well as CXC chemokine receptors—CXCR1, CXCR2, CXCR3, CXCR4, CXCR5, CXCR6, CXCR7 and CXCR8. First, we present basic information on the effect of these chemoattractant cytokines on cancer processes. We then discuss the effect of hypoxia-induced changes on CXC chemokine expression on the angiogenesis, lymphangiogenesis and recruitment of various cells to the tumor niche, including myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), regulatory T cells (Tregs) and tumor-infiltrating lymphocytes (TILs). Finally, the review summarizes data on the use of drugs targeting the CXC chemokine system in cancer therapies. 相似文献
34.
35.
Irena Orović Milica Orlandić Srdjan Stanković 《Multimedia Tools and Applications》2014,70(3):1503-1519
An image watermarking technique based on the concept of JPEG2000 algorithm is proposed. Biorthogonal wavelet 9/7 transform is used to provide a set of coefficients suitable for watermark embedding. The statistical properties of different subbands are analyzed in order to choose the number of decomposition levels and position of subbands, which will assure the best compromise between the watermark transparency and robustness. The JPEG2000 quantization is applied to avoid insignificant wavelet coefficients, while the remaining ones are used for watermarking. The optimal and blind watermark detection is based on the nonlinear score function and appropriate model of coefficients distribution. The performance of the proposed procedure is tested on examples with various images, showing robustness under different attacks, while maintaining high image quality. 相似文献
36.
Saltiness and fattiness were systematically varied in combinations of wheat bread (unsalted vs regular-salt), spread (none vs regular-salt and regular-fat), cheese (low-salt and low-fat vs low-fat). All possible combinations, amounting to sixteen samples of sandwich and milk, were presented to 43 subjects for ratings of pleasantness. The subjects also rated the pleasantness of individual components. The unsalted bread without spread but with low-salt, low-fat cheese and any of the milk types received the lowest hedonic ratings, whereas the regular-salt bread with spread and with any of the cheese and milk options received the highest. The pleasantness of individual components predicted the pleasantness of a combination by only 10–40% (multiple regression analysis). Thus the pleasantness of an entity depended on the pleasantness of components only to a very limited extent. The absence of major elements, such as spread on bread or the salty taste in bread, had major effects on acceptance. 相似文献
37.
We present the first dc-measurements on a 2-dimensional (2D) electron system floating above a liquid
4
He-film which covers a structured metal surface. With our arrangement of a source-, gate-, and drain-electrode a 2-dimensional charge transport is realized in analogy to a field-effect-transistor. The electrons which are moving along the x-direction due to different dc potentials are directly measured. This dc current, of the order of pA, is strongly dependent on the applied split-gate voltage. So the electrons were laterally confined to a narrow channel between the two gate electrodes. The effective width of the channel is reduced by the gate potential, so that a quasi-1D configuration can be realized. The measured electron current through the split-gate is analyzed and discussed on grounds of reduced dimensionality and 1D electron transport behaviour. 相似文献
38.
Grayna Krasnowska Irena Grska Jolanta Gergont 《Molecular nutrition & food research》1995,39(2):149-155
Evaluation of functional properties of beef heart and lip tissue proteins was based on the data obtained in the following determinations: protein extractability, fat emulsifying capacity, emulsion stability, gel forming ability, and water holding capacity after heat treatment. Beef skeletal muscles were used as the control. It was found that extractability of proteins of the raw materials was low as well as their ability to stabilize emulsions was on a low level. Proteins soluble at high ionic strength (fraction HIS) of beef heart and lip tissue emulsified 80.7 ml and 68.9 ml of oil/100 mg of protein, respectively, as compared to 106.6 ml in the control group. Analogically, protein soluble at low ionic strength (fraction LIS) emulsified 77.9 ml, 61.2 ml and 100.4 ml of oil, respectively. Emulsion stability of offal proteins appeared to be dependent on ionic strength. Generally at higher concentrations of salt their ability to stabilize emulsions was better as well as their water holding capacity increased. Their gelation properties as compared to control were also low. In each case, the functionality of cardiac proteins proved to be better than that of beef lip tissue. 相似文献
39.
Irena Brook Guy Mechrez Ran Y. Suckeveriene Roza Tchoudakov Shiran Lupo Moshe Narkis 《Polymer Composites》2014,35(4):788-794
Electrically conductive elastomeric nanocomposites containing carbon nanotubes (CNT) and polyaniline (PANI) are reported in the present investigation. The synthesis procedure included an in situ inverse emulsion polymerization of aniline doped with dodecylbenzene sulfonic acid (DBSA) in the presence of CNT and dissolved styrene‐isoprene‐styrene (SIS) block copolymer. The PANI synthesis step was carried out by applying ultrasonic energy. The dispersions obtained were processed by two methods: a recently developed precipitation‐filtration procedure, and a conventional drop‐cast procedure. The techniques developed resulted in homogeneous exfoliated PANI coated nanotubes within the elastomeric matrix. The presence of CNT/PANI in the SIS elastomeric matrix affects thermal, mechanical, and electrical properties of the nanocomposites. The formation of continuous three‐dimensional CNT/PANI networks prepared via the precipitation‐filtration method enhances the nanocomposite properties. Contrarily, the intermittent three‐dimensional network prepared by conventional drop‐cast method leads to inferior properties. Nanocomposites produced by both techniques are observed by HRSEM. The two processing techniques result in different structures, which affect the physical properties of the materials produced. A relatively low percolation threshold for both methods was determined. The Young's modulus of the SIS/CNT/PANI significantly increased in the presence of CNT. The precipitation‐filtration technique yields an improved nanocomposite product compared to the drop‐cast route. POLYM. COMPOS., 35:788–794, 2014. © 2013 Society of Plastics Engineers 相似文献
40.
Phenol content,antioxidant activity and metal composition of Croatian wines deriving from organically and conventionally grown grapes 总被引:2,自引:0,他引:2
Ivana Vinković Vrček Mirza Bojić Irena Žuntar Gordana Mendaš Marica Medić-Šarić 《Food chemistry》2011
The present study was performed to evaluate the antioxidant capacity, the polyphenol and metal content of conventionally and organically produced wines, which underwent similar winemaking processes. The wine grapes were grown under well-defined organic and conventional conditions from the two different wine-growing sub-regions of Croatia, Prigorje and Southern Dalmatia. The values of antioxidant activity, as evaluated by two free radical methods, ABTS and DPPH, was found systematically higher in organic wines compared to conventional ones. In a reversed phase HPLC analysis, used in order to characterise the phenol fraction of wines, higher concentrations of chlorogenic acid, ferulic acid, catechin, trans-resveratrol, all studied hydroxybenzoic acids and flavonols were found in the organically produced wines. No apparent trend was found in the metal contents of the wines, but ICP-MS analysis confirmed that both wine productions, organic and conventional, were well within the toxicological safety limits. 相似文献