全文获取类型
收费全文 | 243篇 |
免费 | 14篇 |
专业分类
电工技术 | 3篇 |
综合类 | 31篇 |
化学工业 | 62篇 |
金属工艺 | 12篇 |
机械仪表 | 2篇 |
建筑科学 | 6篇 |
能源动力 | 9篇 |
轻工业 | 36篇 |
水利工程 | 3篇 |
无线电 | 9篇 |
一般工业技术 | 30篇 |
冶金工业 | 24篇 |
自动化技术 | 30篇 |
出版年
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 6篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 9篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 11篇 |
2013年 | 9篇 |
2012年 | 12篇 |
2011年 | 17篇 |
2010年 | 15篇 |
2009年 | 5篇 |
2008年 | 22篇 |
2007年 | 12篇 |
2006年 | 10篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 9篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1972年 | 1篇 |
1957年 | 1篇 |
1925年 | 1篇 |
排序方式: 共有257条查询结果,搜索用时 15 毫秒
1.
Antonela Taddia María Julia Boggione Gisela Tubio 《International Journal of Food Science & Technology》2019,54(4):1027-1035
Agroindustrial by-products are an abundant source of biocompounds that contain valuable nutrients, which are not exploited. In this work, lignocellulosic wastes (LW) were used in submerged fermentation (SmF) and solid-state fermentation (SSF) by Aspergillus niger NRRL3 to obtain valuable enzymes required in industries. SmF using soya bean hulls (SH), wheat bran (WB) and a by-product of wheat flour (F) produced the highest activities of endo-1,4-β-xylanase (Xyl) and endo-1,4-β-D-glucanase (EG) being at least 3 times lower than those obtained by SSF. The highest ratio of Xyl to EG was obtained in SmF with F. Xyl obtained by SmF with WB was the most thermally resistant. The enzymatic extract obtained in SmF using SH presented a high power of saccharification. The production of enzymes for further application such as bioethanol generation process revalue these LW and can help offset growing environmental problems. 相似文献
2.
In Situ Scanning Electron Microscopy Observation of Growth Kinetics and Catalyst Splitting in Vapor–Liquid–Solid Growth of Nanowires 下载免费PDF全文
Xing Huang Zhu‐Jun Wang Gisela Weinberg Xiang‐Min Meng Marc‐Georg Willinger 《Advanced functional materials》2015,25(37):5979-5987
In situ observations during vapor–liquid–solid (VLS) growth of semiconductor nanowires in the chamber of an environmental scanning electron microscope (ESEM) are reported. For nanowire growth, a powder mixture of CdS and ZnS is used as a source material and silver nanoparticles as a metal catalyst. Through tracing growth kinetics of nanowires, it is found that nanowires with a relatively bigger catalyst droplet on the tip grow faster. Intriguingly, it is also found that the growth of nanowires can involve catalyst splitting: while the majority of catalyst remains at the nanowire tip and continues facilitating the growth, a portion of it is removed from the tip due to the splitting. It remains attached to the nanowire at the position where the splitting occurred and subsequently induces the growth of a nanowire branch. As far as it is known, this is the first time that catalyst splitting is revealed experimentally in situ. It is proposed that the instability of catalyst droplet caused by the volume increase is the main reason for the splitting. It is believed that in situ growth inside the ESEM can largely enrich our understanding on the metal‐catalyzed VLS growth kinetics, which may open up more opportunities for morphology‐controlled synthesis of 1D semiconductor nanowires in future study. 相似文献
3.
4.
Julia E. Tasca Agustín Ponzinibbio Gisela Diaz Rodolfo D. Bravo Araceli Lavat María G. González 《Topics in Catalysis》2010,53(15-18):1087-1090
An efficient protocol for the rapid room temperature deacetylation of carbohydrate derivatives using CuFe2O4 nanoparticles as an inexpensive and reusable catalyst is presented. After separation of the catalyst with an external magnet, the reaction products are easily obtained in good purity and excellent yields. 相似文献
5.
Through the natural evolutionary process, organisms have been improving amazing mineralized materials for a series of functions using a relatively few constituent elements. Biomineralization has been widely studied in the last years. It is important to understand how minerals are produced by organisms and also their structure and the corresponding relationship with the properties and function. Moreover, one can look at minerals as a tool that could be used to develop high performance materials, through design inspiration and to find novel processing routes functioning at mild conditions of temperature, pressure and solvent type. As important as the molecular constituents are structural factors, which include the existence of different levels of organization and controlled orientation. Moreover, the way how the hierarchical levels are linked and interfacial features plays also a major role in the final behavior of the biogenic composite. The main aim of this work is to review the latest contributions that have been reported on composite materials produced in nature, and to relate their structures at different length scales to their main functions and properties. There is also an interest in developing new biomimetic procedures that could induce the production of calcium phosphate coatings, similar to bone apatite in substrates for biomedical applications, namely in orthopedic implants and scaffolds for tissue engineering and regenerative medicine; this topic will be also addressed. Finally, we also review the latest proposed approaches to develop novel synthetic materials and coatings inspired from natural-based nanocomposites. 相似文献
6.
Lydia Toscano Gisela MonteroMargarita Stoytcheva Héctor CampbellAlejandro Lambert 《Biomass & bioenergy》2011,35(1):26-31
Oil derived fuels constituted a main energy source during the last fifty years, although their high price limited their accessibility. Prospective studies indicated that economic and environmental problems promoted biodiesel production using biomass and residues like animal fat, along with meat and bones, among others. The regional inventory of the available fat in meat industry, as well as the estimation of the biodiesel potential production demonstrated that the biodiesel generated from animal fat, combined with diesel from oil in a 2% biodiesel blend could power 25% of the trucks and passenger vehicles registered in 2007 in Baja California, Mexico. 相似文献
7.
In the current study the savings of CO2 emissions due to the use of ground source heat pump (GSHP) systems was investigated in comparison to conventional heating systems. Based on a subsidy program for GSHP systems in southwest Germany, the regional, average, and total CO2 savings of 1105 installed GSHP systems were determined on a regional scale. The emitted CO2 per kWh of heating demand for the studied scenario resulted in 149 g CO2/kWh for GSHP using the German electricity mix and 65 g CO2/kWh using the regional electricity mix, which results in CO2 savings of 35% or 72%, respectively. Similar CO2 avoidances of GSHP systems were found in American and European studies ranging between 15% and 77% strongly depending on the supplied energy for the heat pumps and the efficiency of installation. The resulting CO2 savings for one installed GSHP unit in the present study therefore range between 1800 and 4000 kg per year. Nevertheless, the minimum average total annual CO2 savings of all installed GSHP systems due to the subsidy program amounted to 2000 tons per year. The maximum regional avoided additional CO2 emissions are primarily associated with the affluent suburbs of the most densely populated area in the region. In 2006 the total contribution of CO2 savings due to GSHP systems in Germany was only about 3.4% of the total renewable energies. However, continuously rising numbers of installed GSHP units and the increasing use of renewable electricity demonstrate that there is a fine opportunity to substantially avoid additional CO2 emissions associated with the provision of heating (and cooling) of buildings and other facilities. 相似文献
8.
Guillermo Calleja Juan A. Botas M. Gisela Orcajo Manuel Sánchez-Sánchez 《Journal of Porous Materials》2010,17(1):91-97
Several discrepancies have emerged about the preparation methods of MOF-5 material, one of the adsorbents more studied for
hydrogen storage, because different synthesis procedures give rise to apparently isostructural materials but actually having
very different textural properties and also showing different hydrogen adsorption capacities. In this work, MOF-5 material
has been successfully synthesized according to the two most extended methods, and the respective resulting materials, IRMOF-1
and MOCP-L, have been widely characterized. Powder X-ray diffraction confirmed that MOF-5 is the main crystallized phase obtained
in both cases, and that the MOCP-L product contains some ZnO impurities, mainly in the form of segregated crystals that appear
preferentially outside the micropores. The presence of ZnO in the MOCP-L material has been also confirmed by other characterization
techniques. On the other hand, interpenetrated networks in the MOCP-L material are not significant, appearing in any case
at a similar extent than in IRMOF-1; consequently it cannot be considered for explaining the differences observed in the adsorption
capacity of both materials. These differences cannot be completely explained simply by the segregated ZnO impurities, so the
presence of some ZnO nanocrystals partially blocking the micropores of MOCP-L must be admitted. 相似文献
9.
Physicochemical Characterization of a Heat Treated Calcium Alginate Dry Film Prepared with Chicken Stock 下载免费PDF全文
Germán D. Báez Gisela N. Piccirilli Griselda A. Ballerini Agustín Frattini Pablo A. Busti Roxana A. Verdini Néstor J. Delorenzi 《Journal of food science》2017,82(4):945-951
Solid sodium alginate was dissolved into chicken stock in order to give a final alginate concentration of 0.9 percent (w/v). Calcium ions present in chicken stock were enough to induce ionic gelation. After drying, Fourier transform infrared spectroscopy, thickness and mechanical properties of films obtained were determined. Calcium alginate‐chicken stock films were heated at 130 °C for different times between 0 and 15 min. Mechanical and optical studies, differential scanning calorimetry, visual aspect and scanning electron microscopy were carried out to describe physicochemical properties of heat treated films. Heating developed a maroon ochre color and increased the brittleness (crispness) of the films related to the intensity of the treatment. Differential scanning thermometry and study on appearance of the films suggested that Maillard reactions may be responsible for the observed changes. Maillard reactions mainly occurred between reducing sugar monomers and free amino groups of gelatin peptides present in the chicken stock, and between alginate and gelatin peptides to a lesser extent. In addition, the plasticizing effect of fat added with chicken stock was also studied. These studies suggest a potential use of heat treated chicken stock films as a substitute of roasted chicken skin. 相似文献
10.
Katrina M. Nordstrom Anne M. Belcher Gisela Epple Kay L. Greenfield James J. Leyden Amos B. Smith III 《Journal of chemical ecology》1989,15(2):629-639
The resident skin surface microflora of 12 male and three femaleSaguinus fuscicollis was studied. The suprapubic-circumgenital gland surface and the perirectal area were most heavily colonized (106–108 colony forming units/cm2), but high numbers of organisms were also present on the abdomen, the sternal gland surface, and palms and plantar surfaces. Bacteria were also recovered from hair clippings as well as from shaven skin surface, although at much lower densities (102–104 colony forming units/cm2). Coagulase negative staphylococci, gram-negative bacteria,Streptococcus species and coryneform bacteria were most dominant.Staphylococcus aureus and species ofBacillus were also present. Fungi, yeast, and dermatophytes were infrequently recovered or completely absent. The microbial flora of these tamarins appears to be closely associated with the secretions of the circumgenital scent gland and would therefore be ideally situated to participate in the generation or modification of chemical signals. 相似文献