全文获取类型
收费全文 | 10463篇 |
免费 | 1077篇 |
国内免费 | 371篇 |
专业分类
电工技术 | 164篇 |
综合类 | 583篇 |
化学工业 | 4547篇 |
金属工艺 | 507篇 |
机械仪表 | 118篇 |
建筑科学 | 180篇 |
矿业工程 | 406篇 |
能源动力 | 507篇 |
轻工业 | 2244篇 |
水利工程 | 35篇 |
石油天然气 | 435篇 |
武器工业 | 12篇 |
无线电 | 287篇 |
一般工业技术 | 981篇 |
冶金工业 | 582篇 |
原子能技术 | 284篇 |
自动化技术 | 39篇 |
出版年
2024年 | 48篇 |
2023年 | 173篇 |
2022年 | 322篇 |
2021年 | 374篇 |
2020年 | 431篇 |
2019年 | 374篇 |
2018年 | 344篇 |
2017年 | 402篇 |
2016年 | 411篇 |
2015年 | 370篇 |
2014年 | 594篇 |
2013年 | 740篇 |
2012年 | 804篇 |
2011年 | 773篇 |
2010年 | 539篇 |
2009年 | 508篇 |
2008年 | 455篇 |
2007年 | 571篇 |
2006年 | 571篇 |
2005年 | 469篇 |
2004年 | 403篇 |
2003年 | 336篇 |
2002年 | 322篇 |
2001年 | 273篇 |
2000年 | 251篇 |
1999年 | 212篇 |
1998年 | 155篇 |
1997年 | 125篇 |
1996年 | 99篇 |
1995年 | 80篇 |
1994年 | 65篇 |
1993年 | 66篇 |
1992年 | 51篇 |
1991年 | 43篇 |
1990年 | 31篇 |
1989年 | 21篇 |
1988年 | 18篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 16篇 |
1984年 | 10篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1981年 | 2篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1976年 | 2篇 |
1961年 | 1篇 |
1959年 | 4篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
用共沉淀法制备Fe3O4磁流体,总结出用十二烷基磺酸钠与聚乙二醇作为表面活性剂制备水基磁流体的合适条件:(1)反应温度为室温或不高于35℃;(2)表面活性剂十二烷基磺酸钠的最佳用量为0.0030~0.0040 g/80 mL;(3)第一次包裹的最佳pH为9~10;(4)聚乙二醇作为第二次包裹的表面活剂时,体系最佳温度为40℃左右;(5)表面活性剂聚乙二醇的最佳用量为0.0050~0.0060 g/80 mL。通过实验制得了能稳定存在180 d的水基磁流体。并用透射电镜、红外光谱、分光光度计、古埃磁天平等进行了初步表征。 相似文献
82.
醇醚羧酸盐在日化产品中的应用性能研究 总被引:5,自引:0,他引:5
考察了脂肪醇聚氧乙烯醚乙酸钠(AE9C Na)的生物降解性和酸、碱水解稳定性,研究了AE9C Na在洗衣粉、肥皂及香波中的应用性能。结果表明,AE9C Na易生物降解,在整个pH值范围内具有良好的酸、碱水解稳定性;在普通肥皂中添加AE9C Na作钙皂分散剂,大大提高了其去污力、抗硬水性,在冷水中的溶解性及织物洗后纤维表面的光滑柔软性;与洗衣粉各助剂及常用各类型表面活性剂配伍性能良好,特别在高硬度水中显示出强大的去污力和钙皂分散能力;在香波中表现出强的起泡、稳泡能力和良好的增调作用。 相似文献
83.
对直接法生产两钠(硝酸钠和业硝酸钠)的工艺过程作了简介,分析了原设计中尾气分离装置存在的缺陷,对尾气分离装髓进行了改造并取得了良好的效果。 相似文献
84.
介绍了一种新的氨化-还原试剂———二烷基胺硼氢化锂,讨论了它在卤代苯腈中的应用,其结果为o 卤代苄腈在与通用的新氨化-还原试剂反应得到相应的氨基苄胺。 相似文献
85.
介绍了FP—640火焰光度计采用低、高标法钠含量的测定。与标准曲线法钠含量测定相比较,该法具有方便、快速、准确度高的特点。 相似文献
86.
M. D. Kurkuri J. N. Nayak M. I. Aralaguppi B. V. K. Naidu T. M. Aminabhavi 《应用聚合物科学杂志》2005,98(1):178-188
Blend membranes of poly(vinyl alcohol) (PVA) and sodium alginate (NaAlg) were prepared by solution casting and crosslinked with glutaraldehyde (GA). Polymer blend compatibility was studied in water by measuring solution viscosity at 30°C. From the viscosity data, interaction parameters were determined to find the blend compatibility. Thickness of the membranes ranged between 35 and 40 μm. Circular disc‐shaped samples were cut from the thin membranes to perform gravimetric sorption experiments in water + 1,4‐dioxane and water + tetrahydrofuran mixtures at 30°C. Diffusion coefficients were calculated using Fick's equation. Concentration profiles of liquids were computed by solving Fick's equation under suitable boundary conditions. Diffusion coefficients show a dependence on the composition of the blends as well as composition of binary mixtures. A correlation was attempted between concentration profiles and diffusion coefficients of the transporting liquids. Degree of swelling and sorption coefficients were calculated from the gravimetric sorption data. Sorption kinetics was studied using an empirical equation to understand the nature of sorption–diffusion anomalies. Membrane selectivity for water + 1,4‐dioxane and water + tetrahydrofuran mixtures were calculated from the pervaporation experiments. A correlation between sorption and membrane selectivity was attempted. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 178–188, 2005 相似文献
87.
The micellar properties of aqueous binary mixed solutions for two systems consisting of sodium cholate (NaC)-octaoxyethylene
glycol mono n-decyl ether (C10E8) and sodium glycocholate (NaGC)-C10E8 have been studied on the basis of surface tensions, polarity of the micelle interior and the mean aggregation number. Application
of two theoretical treatments, based on regular solution and excess thermodynamic quantities for critical micellar concentration
(CMC) data from surface tension curves of two mixed systems showed that the mole fraction of each bile salt in the mixed micelles
near the CMC is lower than that of the corresponding prepared mole fraction in the mixed solution. The polarity of the interior
suggested that the hydrophobicity of intramicelles increased with the increase of the mole fraction of bile salt in the mixed
solution and that the mixed micelles become dramatically more hydrophobic at a mole fraction of 0.68 for NaGC−C10E8 system and 0.75 for NaC−C10E8 system, respectively. This implies that the micelles become richer in the bile salt molecules and the tendency appears strongly
for NaGC−C10E8 system due to the strong cohesion between the conjugated glycines in the NaGC molecules. The decrease of aggregation number
with the increase of the mole fraction of bile salts shows that the micelles approach those of the single system of each bile
salt. This supports the previously mentioned facts. 相似文献
88.
89.
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
90.
以糊精为原料,三偏磷酸钠为交联剂,利用反相微乳液法制备糊精纳米微球,并对头孢曲松钠的吸附载药和释药性能进行了研究。为模拟人体血液环境,选取了pH 7.4的磷酸二氢钠-磷酸氢二钠缓冲液为介质考查了糊精微球的吸附载药及降解性能。实验表明,纳米糊精微球对头孢曲松钠的载药率为9.44%,载药能力随着投药量的增加而增加,温度对载药能力的影响不显著,在α-淀粉酶存在的条件下,降解6 h后有23.94%的纳米糊精微球被降解。 相似文献