全文获取类型
收费全文 | 202篇 |
免费 | 10篇 |
国内免费 | 2篇 |
专业分类
化学工业 | 20篇 |
机械仪表 | 4篇 |
建筑科学 | 8篇 |
矿业工程 | 22篇 |
能源动力 | 13篇 |
轻工业 | 96篇 |
石油天然气 | 14篇 |
无线电 | 1篇 |
一般工业技术 | 21篇 |
冶金工业 | 7篇 |
原子能技术 | 5篇 |
自动化技术 | 3篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 2篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 6篇 |
2013年 | 9篇 |
2012年 | 8篇 |
2011年 | 20篇 |
2010年 | 4篇 |
2009年 | 25篇 |
2008年 | 21篇 |
2007年 | 25篇 |
2006年 | 20篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2003年 | 7篇 |
2002年 | 1篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1988年 | 1篇 |
排序方式: 共有214条查询结果,搜索用时 15 毫秒
1.
攀枝花矿产资源特征及循环经济发展策略探讨 总被引:2,自引:0,他引:2
文章着重描述了攀枝花矿产资源特征、资源矿物流向和资源产品定位,分析了资源矿物使用行业的不同特点,明确了针对攀枝花矿产资源利用的循环经济目标,根据资源循环利用技术水平和资源循环开发现状,提出了攀枝花矿的循环经济发展策略. 相似文献
2.
3.
Kevin Mitchell 《Architectural Design》2015,85(1):38-45
Despite a distinguished heritage of learning in the Middle East, the expansion of provision for higher education is currently at an unprecedented scale. The Gulf States, in particular, are seeking to keep up with accelerated population growth and a demographic ‘youth bulge’. Guest-Editor Kevin Mitchell describes the architectural approaches employed in the design of institutions in the region from the first universities in Saudi Arabia to Foster + Partners's ground-breaking sustainable design for the Masdar Institute in Abu Dhabi and future projects. 相似文献
4.
5.
Kin Weng KongLye Yee Chew K. Nagendra PrasadCheng Yuon Lau Amin Ismail Jian SunBahareh Hosseinpoursarmadi 《Food research international (Ottawa, Ont.)》2011,44(7):2332-2338
The nutritional and antioxidant properties of peels, pulp and seeds of kembayau (Dacryodes rostrata) fruits were evaluated. Kembayau seeds and pulp were rich in fat, while peels had the highest ash contents. Potassium was the most prevalent mineral in peels (380.72-1112.00 mg/100 g). In kembayau fruits, total flavonoid content (1012.74-28,022.28 mg rutin equivalent/100 g) was higher than total phenolic and total monomeric anthocyanin contents. Kembayau seeds exhibited high flavonoid and phenolic contents compared to the contents in peels and pulp. Antioxidant capacities were also higher in seeds as typified by trolox equivalent antioxidant capacity assay (51.39-74.59 mmol TE/100 g), ferric reducing antioxidant power assay (530.05-556.98 mmol Fe2+/100 g) and by 1,1-diphenyl-2-picryl hydrazyl radical scavenging activity (92.18-92.19%) when compared to peels and pulp. Pulp and peels of kembayau fruit may be an important source of energy and minerals for human consumption, while seeds have a good potential as antioxidants. 相似文献
6.
Mercedes Álvarez Isabel M. Moreno Silvia Pichardo Ana M. Cameán A. Gustavo González 《Food chemistry》2012
Fifty wines from the Denomination of origin (DO) of Condado de Huelva were analysed for mineral content by measuring 12 elements (Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, P, Sr and Zn) using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). Samples were previously digested by heating with H2O2/HNO3 mixture. The results obtained showed that metal data set were non-normally distributed and accordingly, non-parametric statistics were applied. The average levels (medians) of these elements found in the samples are as follows, in mg/L: 2.54 (Al); 0.06 (Ba); 82.58 (Ca); 0.21 (Cu); 3.53 (Fe); 865.34 (K); 68.87 (Mg); 0.71 (Mn); 32.77 (Na); 71.61 (P); 0.48 (Sr); 0.56 (Zn). The interrelation of metal couples was studied through the Spearman non-parametric sample correlation, being Fe/Al, P/Mg, and Zn/Ba the most important correlations established. As a result of this study, we can suggest that the contribution to the safety intake limits (per week) of the studied elements through the wine consumption is not significant. Actually, they range between 0.1% in Fe and 11.9% in Mg, for normal drinkers. 相似文献
7.
研究氦在矿物中的初次运移过程是认识氦气成藏机制的基础。研究对氦的产生、扩散和释放过程及主要控制因素进行了系统综述。放射性元素U和Th发生α衰变后,产生的氦在晶格中可发生间隙迁移、与缺陷位复合,并通过自捕陷、迁移合并或热融合方式形成氦泡并长大,氦泡贯通后促进氦释放。氦也可通过α衰变形成的裂变径迹释放。氦源岩组成与晶体结构不同时,矿物对氦的封存能力存在显著差异;高温有利于氦的扩散与氦泡的长大,促进氦的释放;压裂及矿物转化过程也可引起氦的迅速释放。阐明氦初次运移的微观过程与主控因素,可为系统认识氦气的来源、运移聚集等成藏过程,以及氦气成藏理论的建立提供重要的理论基础。 相似文献
8.
Infant formula developed by manufacturers requires a rigorous control of composition, particularly those elements added routinely in an attempt to mimic the mineral composition of human milk. A total of 97 different types of powdered infant formulae (preterm, adapted starter, adapted follow-up, toddler, specialised and soy-based formulae) commercially available in Spain were studied. It is noteworthy great differences in mineral (Ca, P, Mg) and trace element (Zn, Fe, Cu, Mn) contents found between analysed and listed in label information. The development of a fast, simple and direct slurry method for the determination of these essential micronutrients in infant formula by inductively coupled plasma optical emission spectrometry (ICP OES) and flame atomic absorption spectrometry (FAAS) was performed in order to help in quality control tasks. Infant formula samples were solubilised using different amounts of several different solvents. An addition of 250 μL of a solution 10% tetramethylammonium hydroxide and 25% ammonium hydroxide were required for the accurate quantification of Ca and P, Mg, Zn, Fe, Cu and Mn, respectively. The standard reference material 1549 non-fat milk powder was solubilised to compare the validity of assayed methodology following slurry nebulisation and traditional microwave-assisted acid digestion method. Good agreement of the analytical results by both ICP OES and FAAS, with the certified values was obtained. Method performance parameters (accuracy, precision and methodological detection limits) were determined for studied elements to check the quality and usefulness of the optimised slurry method. The analytical procedure was applied successfully to the analysis of a representative group of infant formulae. Levels of analysed elements were graphically represented, showing an acceptable comparability between slurry and acid-mineralisation method set by linear correlation coefficients and slopes close to the unit. The described simple and slurry method is appropriate, as an attractive alternative, for routine control analysis of added essential elements in infant formulae regardless of predominant protein type used in manufacture. 相似文献
9.
Fruits and leafy vegetables are believed to occupy a modest place as a source of trace elements due to their high water content.
Most of nutrient requirements can be met by increasing the consumption of fruits and vegetables to 5–13 servings/day. In addition
to meeting nutrient intake levels, greater consumption of fruits and vegetables is associated with reduced risk of cardiovascular
disease, stroke, and cancers of the mouth, pharynx, esophagus, lungs, stomach, and colon. Therefore, vegetable and fruit consumption
prevents sickness in population. Results in this research showed that Portulaca oleracia Linn. contains high value of macro-elements such as sodium (7.17 mg/g), potassium (14.71 mg/g), and calcium (18.71 mg/g),
and high ash value in comparison with other plants. Also, Eulophia ochreata Lindl. has maximum micro-elements such as iron (5.04 mg/g) and zinc (3.83 mg/g) in comparison with other plants in this study.
Therefore, we can conclude that P. oleracia Linn. has high nutritional values from the viewpoint of macro-elements such as sodium, potassium, and calcium; and because
E. ochreata Lindl. has micro-elements in maximum amounts such as iron and zinc in comparison with other edible plants, it has high nutritional
value from the viewpoint of the above trace (micro) elements. Momordica dioicia Roxb. or Cordia myxa Roxb have the lowest nutritional values because they have ash minimum values. M. dioicia Roxb. contains minimum values of sodium and calcium, but C. myxa Roxb. has zinc minimum value. Alocacia indica Sch., Asparagus officinalis DC., Chlorophytum comosum Linn., C. myxa Roxb., E. ochreata Lindl. have medium nutritional values. 相似文献
10.
The use of High Pressure Grinding Rollers (HPGR) has been widely reported to have major benefits in the treatment of minerals such as iron ore and diamonds. To date there have been few investigations into its use in the treatment of ores containing Platinum-Group Minerals (PGMs). HPGRs are known to reduce energy consumption and wear costs and improve the throughput in the circuit. In the present investigation the effect of the comparative use of HPGR and conventional crushing in combination with either dry or wet rod milling on the flotation of PGMs was studied using batch flotation. Previous studies of a base metal sulphide had shown that either HPGR or conventional crushing followed by dry milling produced the highest grades and recoveries (Palm et al., 2010). However in the present study it was observed that a similar treatment of Platinum-Group Minerals produced the poorest results and the highest grades and recoveries were obtained for the case of conventional crushing in combination with wet milling. The HPGR showed no advantages in terms of flotation performance and dry milling produced particularly poor flotation results.The results were investigated further using various surface characterization techniques in order to determine the reason for the decrease in grades and recoveries of platinum when using dry milling and HPGR as opposed to the case for base metal sulphides. The feed and product samples were analysed using ToF-SIMS, XPS and MLA. The paper will propose reasons to explain the different flotation behaviour of the two ore types following the various comminution processes focusing on the surface characteristics of the ores, the particle size distribution and the pulp chemistry. 相似文献