全文获取类型
收费全文 | 5127篇 |
免费 | 532篇 |
国内免费 | 189篇 |
专业分类
电工技术 | 102篇 |
综合类 | 336篇 |
化学工业 | 1843篇 |
金属工艺 | 165篇 |
机械仪表 | 102篇 |
建筑科学 | 305篇 |
矿业工程 | 317篇 |
能源动力 | 138篇 |
轻工业 | 1135篇 |
水利工程 | 70篇 |
石油天然气 | 428篇 |
武器工业 | 7篇 |
无线电 | 94篇 |
一般工业技术 | 250篇 |
冶金工业 | 489篇 |
原子能技术 | 24篇 |
自动化技术 | 43篇 |
出版年
2024年 | 16篇 |
2023年 | 50篇 |
2022年 | 152篇 |
2021年 | 204篇 |
2020年 | 179篇 |
2019年 | 129篇 |
2018年 | 124篇 |
2017年 | 164篇 |
2016年 | 172篇 |
2015年 | 168篇 |
2014年 | 305篇 |
2013年 | 298篇 |
2012年 | 409篇 |
2011年 | 349篇 |
2010年 | 265篇 |
2009年 | 269篇 |
2008年 | 213篇 |
2007年 | 355篇 |
2006年 | 304篇 |
2005年 | 259篇 |
2004年 | 199篇 |
2003年 | 205篇 |
2002年 | 199篇 |
2001年 | 183篇 |
2000年 | 147篇 |
1999年 | 116篇 |
1998年 | 94篇 |
1997年 | 73篇 |
1996年 | 43篇 |
1995年 | 44篇 |
1994年 | 50篇 |
1993年 | 18篇 |
1992年 | 17篇 |
1991年 | 18篇 |
1990年 | 10篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有5848条查询结果,搜索用时 296 毫秒
91.
92.
介绍了2006年整个中国日化行业所发生的主要事件,包括政府机关通报批评、媒体批露、市场上日化产品的抽查和检测情况、有关化妆品法律法规的制定情况、企业间的收购和品牌的购买等等。 相似文献
93.
导电织物在可穿戴电子领域前景广阔,但在使用过程的稳定性仍需提高。通过缩合反应,在棉织物(CF)上接枝了γ-巯丙基三甲氧基硅烷(MPTS),再利用化学镀的方式沉积银颗粒,制备出棉/银复合织物电极(Ag/M-CF)。Ag/M-CF的表面方阻低至0.04 Ω/sq,而且在多个方面(洗涤、拉伸、弯曲和氧化)都有良好的稳定性。洗涤200次后,表面方阻仅为1.88 Ω/sq,导电性能良好,满足实际需要;拉伸5%后,表面方阻仅为1.00 Ω/sq;经过3000次弯曲后,Ag/M-CF的表面方阻增加至1.38 Ω/sq;在恒温恒湿环境中放置9周后,表面方阻仅为0.50 Ω/sq。将洗涤前后的Ag/M-CF植入智能服装中,都能成功捕捉到人体在运动状态下的心电信号,而且测得的心率几乎相同。除此之外,Ag/M-CF还具有良好的机械性能和抗菌性。关键词:织物电极;洗涤稳定性;弯曲性能;耐氧化性能;心电图中图分类号:TS195.5 文献标识码: A 文章编号:1003-5214 (2020) 01-0000-00 相似文献
94.
95.
Applications of electric fields during washing of filter cakes increases the removal rate of ions from the cake mother liquor, and under appropriate conditions the field also increases the wash flow rate by electroosmosis. Experimental data that show the key effects of the fields on the rates of ion mass transfer are presented: with the downstream electrode acting as a cathode, cation removal rates are increased whilst the removal rate of the anions is decreased. The concentration profile of the cations with washing time shows an increase in concentration to a value above that of the mother liquor, before it decreases due to displacement by the fresh wash liquor. A model is formulated that describes the advection, dispersion, ion migration and electroosmosis transport processes in the cake. Numerical solution of the model gives cation concentration profiles at the exit of the cake that are in qualitative agreement with the experimental observations. Experimentally measured wash liquor flow rates tend to be lower than what traditional colloid science principles predict by a factor of 5-10: reasons for this difference, supported by experimental work from other researchers, are discussed. 相似文献
96.
97.
Polycrystalline (PbS)1.14(TaS2)2, a misfit layer sulfide, was used as cathodic material for lithium secondary battery. One molar LiClO4 in propylene carbonate (PC) was used as electrolyte. The cell could be galvanostatic discharged down to x = 4.6 [Lix(PbS)1.14(TaS2)2] when the current density was 65 μA cm−2 and the cell was cycled more than 100 times between 3.5 and 1.5 V at a current density of 260 μA cm−2. Lattice expansion increased linearly with lithium content and was less than that reported for the Li/TaS2 system. Chemical diffusion coefficients were determined by a modified version of the galvanostatic intermittent titration technique and they were fairly constant in the composition range 0.2 < x < 1, and an average value of 8.1 × 10−11 cm2 s−1 was calculated. Sodium intercalation was also accomplished, but the uptake of this ion resulting in a significant lattice expansion compared with that observed for lithium ions. Moreover, a similar dependence of the sodium chemical diffusion coefficient on the composition was observed with an average value of 1.4 × 10−10 cm2 s−1, somewhat higher than that of lithium ion. We believe that differences in lattice expansion may be responsible for the differences found in the chemical diffusivity values. 相似文献
98.
我国氯碱工业新时期的发展特点 总被引:2,自引:0,他引:2
在分析了国际、国内经济形势的基础上,提出了我国氯碱行业的发展趋势,即结构调整向大规模,集约化发展;企业改制转制向投资多元化发展,产品结构要实现氯碱平衡、大力发展聚氯乙烯及氯碱的下游精细化工产品。强调指出要建立氯碱行业物流中心,并重视环境保护?建议有条件的企业推行热电与碱联产,实现企业发展。 相似文献
99.
The wettability, surfactivity and the correlation between wettability and surfactivity of sodium diethylhexylphosphate, sodium
diethylhexyl polyoxyethylene phosphate and their complex in NaOH solutions were studied. A complex alkali resistant phosphate
surfactant with good permeability was prepared. The wettability of surfactants was investigated by measuring the immersion
time, sinking time and capillary effects of nature cotton grey fabric in NaOH solutions. The surfactivity of the surfactants
was characterized by measuring the surface tension. The effect of the complex on the surface appearance of cotton grey fabric
was also investigated with a scanning electron microscope (SEM). The results show that all the surfactants exhibit good wettability
for cotton grey fabric in 0.5–5.0 mol/L of NaOH solutions, the complex system exhibits better wettability in 5.0–7.0 mol/L
of NaOH solutions, in comparison with either corresponding single surfactant component employed, and wettability is well correlative
with the surfactivities of the surfactant. SEM images indicate that the cotton grey fabric is well wetted by the alkaline
surfactant solution and the quality of fabric is improved. 相似文献
100.
共轭亚麻酸具有多种有益的生理功能,本文以亚麻油(含53.5%亚麻酸)为原料,氢氧化钾为催化剂,乙二醇为溶剂,碱催化异构化方法制备共轭亚麻酸,采用气相色谱法表征。研究了反应温度、时间、碱油比及溶剂用量对亚麻油共轭化的影响,得到了制备共轭亚麻酸的最佳实验条件。结果表明,当反应温度180℃,反应时间40 min,碱油比(mA∶mO)=3∶1,溶剂油比(VS∶mO)=20∶1时,亚麻酸的共轭收率可达52.70%。该方法能使反应在均相反应体系中较为温和的温度条件下较短的时间内完成。 相似文献