全文获取类型
收费全文 | 3996篇 |
免费 | 95篇 |
国内免费 | 42篇 |
专业分类
电工技术 | 103篇 |
综合类 | 164篇 |
化学工业 | 1270篇 |
金属工艺 | 408篇 |
机械仪表 | 82篇 |
建筑科学 | 139篇 |
矿业工程 | 250篇 |
能源动力 | 161篇 |
轻工业 | 531篇 |
水利工程 | 12篇 |
石油天然气 | 284篇 |
武器工业 | 4篇 |
无线电 | 75篇 |
一般工业技术 | 168篇 |
冶金工业 | 170篇 |
原子能技术 | 31篇 |
自动化技术 | 281篇 |
出版年
2024年 | 3篇 |
2023年 | 23篇 |
2022年 | 33篇 |
2021年 | 59篇 |
2020年 | 66篇 |
2019年 | 61篇 |
2018年 | 61篇 |
2017年 | 77篇 |
2016年 | 107篇 |
2015年 | 88篇 |
2014年 | 162篇 |
2013年 | 248篇 |
2012年 | 153篇 |
2011年 | 336篇 |
2010年 | 249篇 |
2009年 | 290篇 |
2008年 | 200篇 |
2007年 | 200篇 |
2006年 | 179篇 |
2005年 | 193篇 |
2004年 | 139篇 |
2003年 | 147篇 |
2002年 | 114篇 |
2001年 | 89篇 |
2000年 | 102篇 |
1999年 | 106篇 |
1998年 | 77篇 |
1997年 | 74篇 |
1996年 | 69篇 |
1995年 | 99篇 |
1994年 | 68篇 |
1993年 | 57篇 |
1992年 | 61篇 |
1991年 | 47篇 |
1990年 | 17篇 |
1989年 | 15篇 |
1988年 | 14篇 |
1987年 | 8篇 |
1986年 | 12篇 |
1985年 | 7篇 |
1983年 | 2篇 |
1965年 | 3篇 |
1963年 | 1篇 |
1961年 | 3篇 |
1960年 | 1篇 |
1959年 | 1篇 |
1958年 | 3篇 |
1957年 | 2篇 |
1955年 | 2篇 |
1954年 | 1篇 |
排序方式: 共有4133条查询结果,搜索用时 15 毫秒
41.
聚苯胺盐的合成及导电性能研究 总被引:3,自引:0,他引:3
用对甲苯磺酸作为掺杂剂对聚苯胺(PANI)进行掺杂,合成了导电聚苯胺盐(ES)。研究了掺杂剂用量、模压压力、模压温度、氧化剂用量对聚苯胺盐电导率的影响。结果表明:随着掺杂剂用量的增加,PANI的电导率也在不断的增大;当ES所受压力较高时,电导率提高;高温使PANI电导率上升;氧化剂与苯胺的最佳配比为1:1。 相似文献
42.
43.
L. Savary J. Saussey G. Costentin M. M. Bettahar M. Gubelmann-Bonneau J. C. Lavalley 《Catalysis Today》1996,32(1-4):57-61
A VPO/TiO2 catalyst tested in the oxydehydrogenation reaction (ODH) of propane between 300 and 400°C shows satisfactory performances (up to 80% of propene selectivity at 2% of propane conversion at 300°C or 56% of propene selectivity at 9% of propane conversion at 400°C). Addition of water or pyridine in the feed gas tends to decrease the propane conversion and enhances the propene selectivity. It is shown that water increases the number of Brönsted surface acid sites by dissociative adsorption which, in turn, enhances propene selectivity at the expense of the COx selectivity. These results are in good agreement with spectroscopic IR observations performed under catalytic conditions showing that the Lewis acid sites are linked to COxformation, whereas it seems that Brönsted sites would rather be linked to propene formation. 相似文献
44.
本文通过许多实例,指出了氧化还原反应式配平中可能出现的得失电子数不等或电荷数未配平、得失电子关系不对及反应式中酸碱性介质有错误等几种差错,并归纳了在酸碱性水溶液中平衡介质的方法。 相似文献
45.
Characterization of nanoporous materials prepared from montmorillonite clay and its application to the decolorization of mare's milk oil 总被引:1,自引:0,他引:1
J. Temuujin M. Senna Ts. Jadambaa D. Burmaa Sh. Erdenechimeg J. Amarsanaa G. Burmaa 《Journal of Porous Materials》2006,13(1):49-53
Nanoporous materials have been prepared by leaching the purified montmorillonite clay with sulfuric acid (H2SO4) solution with varying concentrations (0.5–2 M) at 80°C for 0.5–4 h. Acid leaching causes partial amorphisation of the clay
with depletion of MgO, Al2O3, CaO and Fe2O3 components mostly from interlayer and octahedral sites. This increases the specific surface area by more than 3 times, i.e.
from 49.1 to 157 m2/g. The pore-size distribution curves calculated from the adsorption isotherms of the leached montmorillonite show that most
of the pores are in the mesoporous region with their diameter ranging 3–4 nm. This material turns out to be appropriate for
bleaching of the mare's milk oil. The chemical and structural changes of the acid-leached montmorillonite are discussed in
terms of the decolorization capacity. 相似文献
46.
Shigezo Naito 《臭氧:科学与工程》2006,28(6):425-429
Ozone has the strongest oxidization effect after fluorine, and this property has been used in sterilization for food and processing plants in Japan. Moreover, there is no fear of toxic residues as with chlorine-based sterilizers and no hazardous trihalomethanes are formed. Based on these advantages, ozone has been used in water and air treatment for food products food materials and food processing plants. Use in the food processing is now increasing in Japan. This paper describes ozone sterilization, introducing sterilization systems and equipment applied to food in Japan. 相似文献
47.
Gwang-Suk You Ji-Whan Ahn Gi-Chun Han Hee-Chan Cho 《Korean Journal of Chemical Engineering》2006,23(2):237-240
This study measures the neutralizing capacity of bottom ash from municipal solid waste incineration of different particle
sizes. We examine the effect of particle size on the weathering process, a method popularly used for stabilization of heavy
metals in incineration of bottom ash. The distribution of particle sizes in municipal solid waste incineration bottom ash
is rather broad, ranging from fine powder to as large as 40 mm in diameter. Although considered a by-product highly suitable
as a road construction material, the high level of heavy metal leaching is an obstacle to its reuse. Weathering, a method
used to reduce heavy metal leaching, is a lengthy process taking over thee months to complete. The chief reaction involved
in weathering is carbonation occurring between Ca(OH)2 in bottom ash and CO2(g) in the atmosphere. During this process, CaCO3 is produced, causing the pH level to drop from over 12 to about 8.2 and reducing heavy metal leaching. In this paper, we
attempt to determine the particle size best suited for reducing the period required for weathering bottom ash by identifying
characteristics of different particle sizes that affect heavy metal leaching and neutralization. 相似文献
48.
交联型单分散聚苯乙烯微球的制备 总被引:1,自引:0,他引:1
以聚乙烯吡咯烷酮(PVP)为分散剂,偶氮二异丁腈(AIBN)为引发剂,乙醇为分散介质,二乙烯基苯(DVB)为交联剂进行了苯乙烯(St)的分散聚合;讨论了引发剂、交联剂、分散剂、单体用量对聚合物粒径及分布的影响,制备了交联型单分散聚苯乙烯微球。实验表明:当交联剂质量分数达到单体质量分数的1%时,微球依然可以保持良好的单分散性。在聚合体系中引入抗坏血酸,使其与微量的氧结合,有效地提高了微球的均匀度。 相似文献
49.
The liquid-liquid equilibrium for the quaternary system of o-xylene(1)+water(2)+propionic acid(3)+1-butanol(4) was measured
at 298.15 K and atmospheric pressure. Binodal curves, tie-lines, a distribution curve, and a selectivity curve for the quaternary
system have been determined in order to investigate the effect of binary solvents, oxylene and 1-butanol, on extracting propionic
acid from aqueous solution. In addition, these experimental tie line data were also compared with the values predicted by
the UNIFAC model. In this study, the UNIFAC model was capable of predicting the compositions of this quaternary system within
an average RMSD of 1.13 mol%.
This paper was prepared at the 2004 Korea/Japan/Taiwan Chemical Engineering Conference held at Busan, Korea between November
3 and 4, 2004. 相似文献
50.
酸性气流脱除物是净化天然气、合成气、煤气时脱除的物质,STW-3#是由该物质制成的样品之一。就STW-3#对NR硫化性能的影响进行了研究。结果表明,STW-3#对NR有较好的硫化促进特性和一定的软化增塑作用;其用量3.0份以下时,硫化特性较差,3.0份以上时硫化特性较好,但超过4.0份时有粘辊和喷霜现象。它与促进剂M并用时,硫化特性与促进剂D相似。 相似文献