全文获取类型
收费全文 | 1354篇 |
免费 | 109篇 |
国内免费 | 42篇 |
专业分类
电工技术 | 4篇 |
综合类 | 79篇 |
化学工业 | 703篇 |
金属工艺 | 57篇 |
机械仪表 | 4篇 |
建筑科学 | 66篇 |
矿业工程 | 53篇 |
能源动力 | 63篇 |
轻工业 | 187篇 |
水利工程 | 7篇 |
石油天然气 | 53篇 |
武器工业 | 3篇 |
无线电 | 6篇 |
一般工业技术 | 166篇 |
冶金工业 | 25篇 |
原子能技术 | 21篇 |
自动化技术 | 8篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 16篇 |
2021年 | 35篇 |
2020年 | 30篇 |
2019年 | 41篇 |
2018年 | 39篇 |
2017年 | 31篇 |
2016年 | 54篇 |
2015年 | 38篇 |
2014年 | 69篇 |
2013年 | 137篇 |
2012年 | 191篇 |
2011年 | 95篇 |
2010年 | 58篇 |
2009年 | 101篇 |
2008年 | 71篇 |
2007年 | 65篇 |
2006年 | 81篇 |
2005年 | 49篇 |
2004年 | 47篇 |
2003年 | 35篇 |
2002年 | 35篇 |
2001年 | 15篇 |
2000年 | 22篇 |
1999年 | 22篇 |
1998年 | 15篇 |
1997年 | 14篇 |
1996年 | 18篇 |
1995年 | 12篇 |
1994年 | 11篇 |
1993年 | 11篇 |
1992年 | 5篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有1505条查询结果,搜索用时 724 毫秒
61.
采用水热法原位改性沙柳生物炭制备磁性多孔炭复合材料,利用SEM、XRD、FT-IR、XPS和BET分别对多孔炭的形貌、结构表征,并研究磁性多孔炭吸附去除废水中亚甲基蓝性能。系列表征分析结果表明磁性复合材料表面疏松多孔,比表面积为63.01 m2/g,含有-COOH、-OH等丰富的官能团。在亚甲基蓝初始质量浓度为50 mg/L、初始pH值为11,投加量为2 g/L、25℃吸附120 min时,亚甲基蓝的吸附率可达88.52%,最大吸附量为218.08 mg/g;吸附过程与Langmuir吸附等温模型拟合较好,符合准二级吸附动力学模型。吸附以化学吸附为主,吸附稳定,无二次污染,吸附剂廉价易得,便于分离,是理想的亚甲蓝废水处理试剂。 相似文献
62.
C.P. Jordão D.M. Carari W.L. Pereira R.M. Almeida M.P.F. Fontes R.L.F. Fontes 《The International journal of environmental studies》2013,70(6):879-897
The relative contribution of organic matter, amorphous and crystalline Fe oxides and Al oxides to soil Zn adsorption was evaluated in contaminated and uncontaminated Brazilian soils. Soil samples were equilibrated with Zn solutions and Zn adsorption was determined using the Langmuir adsorption isotherm. The Fe and Al oxides (non‐silicated clays) and the organic matter contents of the soils were the main contributors to the variation in Zn adsorption. The Zn maximum adsorption capacity in the soil with the greatest sand and organic carbon contents was higher than in the higher clay content soil, which was second in organic carbon content. Related to the whole soil samples, as the soil organic matter was removed, the Zn maximum adsorption capacity decreased in most of the observations. The removal of Fe and Al oxides decreased the soil Zn maximum adsorption capacity in some cases and increased it in others, with no clear variation in the pathway. For both whole soil and soil fractions, the isotherms for Zn adsorption to soil, fitted to the Langmuir equation, showed two linear portions or pathways (Part I and Part II). The bonding energy coefficient was higher in Part I (related to specific chemical adsorption) than in Part II (related to electrostatic interactions), which suggests a higher affinity between Zn and soil particles in Part I as compared with Part II. 相似文献
63.
64.
利用废弃蛋壳制备碳羟磷灰石(简称CHAP),并用作去除废水中Pb^2+的吸附剂。考查了pH值、吸附时间、温度、吸附剂用量以及Pb^2+初始浓度等因素对吸附效果的影响。结果表明:0.6g/L的CHAP对750mg/L的Pb^2+的去除率高达99.9%,吸附容量达到1243.75mg/g。CHAP对Pb^2+吸附的吸附等温线均符合Freundlich和Langmuir两种模式,从Freundlich方程中的常数1/n=0.0184可知,该吸附反应为吸热自发反应,且反应速率快。 相似文献
65.
低温氮吸附法与煤中微孔隙特征的研究 总被引:36,自引:6,他引:36
对不同矿区24个煤样作了低温氮吸附试验,分析了吸附等温线及吸附回线的形态、类型,划分出L1,L2,L3型3种煤的低温氮吸附回线类型,讨论了共与煤中微孔隙发育特征的关系。试验结果表明,煤中孔隙是从小至分子级(孔径约0.86nm)大至无上限的较连续的孔系统,其中孔形结构可分为:开放型透气性Ⅰ类孔;一端封闭的不透气性Ⅱ类孔;细颈瓶形Ⅲ类孔,煤中孔径约小于3nm的孔大多为一端封闭的Ⅱ类孔;细颈瓶形孔的瓶劲直径也是3nm左右。 相似文献
66.
凹凸棒石颗粒吸附剂制备及其性能 总被引:11,自引:1,他引:11
在凹凸棒石黏土中加入低熔点烧结剂,制备了凹凸棒石颗粒吸附剂。实验表明,在600℃下煅烧20min,该颗粒吸附剂具有较低的散失率和良好的吸附性能。颗粒吸附剂对有机染料阳离子红的吸附等温线属于Langmuir型。 相似文献
67.
68.
A. A. Amooey 《中国化学工程学报》2014,22(6):628-633
This research proposes a modified two-dimensional Peng-Robinson equation model to predict adsorp-tion isotherm in adsorbate-adsorbent systems. The parameters of the proposed model are calculated by using the op-timization of experimental data for the different single gas adsorption systems at various temperatures. The experi-mental adsorption equilibrium data of adsorbate-adsorbent systems was compared with the calculated results in our proposed model and the two-dimensional Hill-deBoer equation model. The proposed model as indicated in the re-sults shows a better prediction of the experimental results compared with two others. 相似文献
69.
利用COMPASS力场,采用NPT系综对β-HMX晶体进行了温度为295K,压力为0—27GPa的分子动力学模拟并进行静态力学分析。研究了β-HMX的压缩各向异性,得到了295K下β-HMX的等温线,用不同状态方程对结果进行拟合,求得了零压下β-HMX体积模量民及其关于p的一阶导数K'0。计算结果表明,用不同方程拟合得到的K0和K'0存在差异。通过静态力学分析,得到了弹性系数以及各模量随压力的变化情况,通过对G/K与C12-C44(柯西压)的研究发现JB-HMX的硬度随着压力的增大而增大,在大压力作用下材料由脆性到韧性转变。 相似文献
70.
Ankur Jain Shivani AgarwalDevendra Vyas Pragya JainI.P. Jain 《International Journal of Hydrogen Energy》2010
Laves phases with AB2 compositions are common type of topologically close packed structure. Furthermore, lave phases are capable of dissolving considerable amounts of ternary alloying additions. ZrCr2 crystallized in the hexagonal C14 type of structure is one of interesting candidate among them, but it is not used as storage compound due to its excessive stability, at 323 K the equilibrium pressure is only 1.2 kPa. However the substitution of chromium by other elements can modify the crystal structure, the hydriding capacity and dissociation pressure of hydrogen. In this work Fe has been chosen as a substitute material for Cr and ZrCrFe ternary alloy is prepared using arc furnace. The mechanical alloying process has been introduced to produce nanocrystalline material. This paper presents comprehensive study on structural aspects of ball milled ZrCrFe alloy. On comparison of the XRD data, the broadening was found in the peak width with the increase of milling time which is clear indication of refinement of crystallite size. This refinement could also be confirmed from the SEM analysis also. PCT measurements were performed for a temperature range 303 K–373 K. 相似文献