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排序方式: 共有86条查询结果,搜索用时 31 毫秒
1.
长石溶解及其次生孔隙的形成对砂岩储层质量具有重要影响。为了研究渤海湾盆地渤南洼陷有利孔隙发育带,利用长石溶解-沉淀的热力学和动力学计算,结合薄片分析、孔隙度和渗透率资料,开展了对沙三段长石次生孔隙发育的研究。结果显示,现今的地层水多有利于长石沉淀,部分区域发生长石溶解。结合孔隙度平面分布图和镜下薄片分析可知:孔隙度发育较好的区域主要是钾长石发生溶解,钙长石ΔG < -15 kJ/mol溶解速率较快和钠长石ΔG < 15 kJ/mol沉淀速率较慢的区域。此外,粘土矿物(高岭石等)在长石溶解形成的次生孔隙中的沉淀,降低了储层的渗透率;且在埋深超过3 000 m的区域,地层水中的SiO2(aq)沉淀速率的显著加快降低了储层孔隙度。综上:埋藏环境中,长石的溶解对于次生孔隙的贡献十分重要,但是如果其副产物未发生迁移则对次生孔隙的贡献较小,并且较高的粘土矿物含量会降低储层的渗透率。本文对于利用热力学和动力学模型预测储层发育提供了新的方法。 相似文献
2.
通过使用寡营养人工海水培养基,从深海沉积物中筛选能够降解淀粉的菌株。通过划线培养获得单菌落,并利用革兰氏染色、扫描电镜和gyr B基因测序进行菌株的初步鉴定和系统发育分析。通过采用3,5-二硝基水杨酸法测定该菌株所产生的α-淀粉酶酶活力,并探讨不同淀粉含量、菌株生长温度及生长周期对该α-淀粉酶产量的影响。结果表明:分离获得一株革兰氏阳性菌,能够有效地降解淀粉,形状为杆状,初步确定为解淀粉芽孢杆菌TVG11-1。菌株TVG11-1最适的生长温度和pH分别为45℃和pH7.0,其所产生的α-淀粉酶是一种不依赖淀粉底物的胞外中温淀粉酶,其最适反应温度为60℃,最适反应pH为6.5。本研究将为淀粉糖化以及其它涉及淀粉降解的食品加工过程提供菌种资源。 相似文献
3.
当前,高校的实践教学管理普遍存在传统的相对集中和开放两种实践教学管理模式,它们各自存在优缺点,而且具有一定的互补性。提出探索建立一种全新的、相对独立的实验教学管理模式,以实现传统与开放二者间的优势互补,进而推动高校实践教学质量的进一步提高。 相似文献
4.
To evaluate the metal chromium (Cr) contamination of soil at a chromium-containing slag site by ferrochromium production, the contaminated sites, under slag heap, in the vicinity of slag heap and arable soils near the outlet of sewer channel, and unpolluted site 5 km away from one ferroalloy plant in Hunan Province, China, were selected. The concentrations of total Cr and water soluble Cr in bulk soil samples and profile depth samples were determined. The results show that the soils in the vicinity of slag heap have the highest total Cr content followed by the soils under the slag heap and near the outlet of sewer channel of the factory. The mean concentrations of total Cr in the top soils at above three contaminated locations exceed the critical level of Secondary Environmental Quality Standard for Soil in China by 3.5, 5.4 and 1.8 times. In most Cr polluted soils, total Cr has a relative accumulation in soil depth of 40-60 cm, but this trend is not found in unpolluted soils. The average concentrations of water soluble Cr (Ⅵ) in top soils under slag heap and in the vicinity of slag heap are 176.9 times and 52.7 times higher than that in the uncontaminated soils, respectively. However, water soluble Cr (Ⅵ) contents in soils near sewer channel are all low and the values are close to that in the uncontaminated soils. Although water soluble Cr (Ⅵ) content in soil profiles decreases with soil depths, it in soils under slag heap maintains a high level even at a depth of 100-150 cm. The results imply that the transportation of Cr (Ⅵ) can result in a potential risk of groundwater system in this area. 相似文献
5.
Lead-loaded modified spent grain regenerated by desorption process was investigated. HCl, H2SO4, H3PO4, NaOH, NaCl and ultrapure water were chosen as desorption agents to treat lead-loaded modified spent grain for 30 min. The structures and components of regenerated modified spent grain before and after adsorbing Pb(II) were investigated using scanning electron microscopy(SEM), energy-dispersive analysis of X-ray(EDAX) and Fourier transform infrared spectrometry(FTIR). The results indicate that lead-loaded modified spent grain treated in 0.1 mol/L HCl exhibits higher elution efficiency (86.44%) as compared with other agents. The enrichment of carboxyl and hydroxyl groups susceptible to combine with Pb(II) are observed in the regenerated modified spent grain, which may result in high re-absorption efficiency of Pb(II). Moreover, C—Cl, N—H, C—N and O—H (polysaccharides) also play an crucial role in Pb(II) binding to regenerated modified spent grain. 相似文献
6.
7.
分析湖南省某铁合金厂附近重金属铬在土壤中的分布及迁移特征,在土壤-植物系统中的迁移转化规律,以及铬污染蔬菜对人体的健康风险。结果表明:铁合金厂外排污口、污灌区和对照区土壤的铬含量平均值分别为2239.5,995.33和104.9mg/kg。总铬在排污口附近土壤中主要富集在地表下200-400mm;在污灌区,主要富集于地表下0-200mm;而在对照区,铬浓度从上至下逐渐降低且各层之间富集浓度相差不大。结果也表明芹菜、莴苣和白菜均能够把土壤中吸收的致毒性较强的六价铬转化成低毒的三价铬,且蔬菜中的铬含量平均值为11.95mg/kg。铬在土壤–蔬菜中的生物富集因子大小依次为:白菜〉莴苣〉芹菜。居民每天摄入的铬含量严重超过食物中最大铬允许摄入量,表明铬污染对当地居民存在一定的健康风险。 相似文献
8.
Inhibitory effect of Cr(Ⅵ) on activities of soil enzymes 总被引:1,自引:0,他引:1
To evaluate the influence of various Cr(VI) concentrations (0.05, 0.25, 0.50, 1.00 and 2.00 g/kg) on the activity of soil
enzymes, the activities of catalase, polyphenol oxidase, dehydrogenase, alkaline phosphatase in soils were investigated in
the incubation experiment with a period of 35 d. The results indicate that all the tested Cr(VI) concentrations significantly
inhibit dehydrogenase activity by over 70% after 35 d. The activity of alkaline phosphatase is slightly inhibited during the
whole experiment except for on the day 7. Cr(VI) has no obvious effect on the activity of catalase in soil. On the contrary,
Cr(VI) stimulates the activity of polyphenol oxidase. The results suggest that dehydrogenase activity can be used as an indicator
for assessing the severity of chromium pollution.
Foundation item: Projects(2006AA06Z374, 2007AA021304) supported by the National High-Tech Research and Development Program of China; Project(2008SK2007)
supported by the Key Program of Science and Technology of Hunan Province, China 相似文献
9.
蒙乃尔合金的氩弧焊工艺研究 总被引:1,自引:0,他引:1
通过对蒙乃尔合金氩弧焊工艺的可行性研究结果表明:焊接规范必须控制在恰当的范围内,热输入太强则易产生热裂纹,太弱则易出现熔合不良和夹渣缺陷,增加操作难度。接头HAZ存在一低度,低塑性,低强度区,热裂纹及拉伸断裂多出现于该区。 相似文献
10.