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排序方式: 共有10000条查询结果,搜索用时 281 毫秒
991.
应用结构模糊优化理论对板翅式换热器进行多目标优化设计;给出了构造隶属函数及确定目标函数权重的方法,通过线性加权法将多目标化为单目标求解。应用此软件设计了一台换热器,其实际使用结果表明完全达到设计要求。 相似文献
992.
曹卿 《网络安全技术与应用》2014,(11):174-174
本文介绍的数学题库及自动组卷系统使用了C++/VC课程的基本设计方法,是基于windows平台下的数据库系统,界面有几个模块组成,分别为登录模块,维护模块,浏览模块和出卷模块等模块界面。自动出卷模块和组卷模块为出卷模块包含功能,修改、删除、添加等功能则集合于维护模块。本系统主要运用的后台数据库为Access数据库,选用Visual Basic为开发工具。 相似文献
993.
Iván Jachmanián Lucía Margenat Ana I. Torres Maria A. Grompone 《Journal of the American Oil Chemists' Society》2007,84(6):597-601
The solubility of different ethyl esters derivatized from hake liver oil in supercritical carbon dioxide was studied. A selectivity
factor was used to determine optimal conditions to fractionate the ethyl ester mixture. A strong influence of solvent pressure
and temperature was observed within 8.63–18.04 MPa and 40–70 °C. The lowest total solubility of the ethyl ester mixture was
obtained when using supercritical carbon dioxide at the lowest density (the lowest pressure and the highest temperatures value
tested). The highest discrimination against long-chain polyunsaturated fatty acids (e.g. EPA and DHA) was also obtained at
these above conditions. Conversely, higher solubility and lower selectivity were obtained when solvent density increased.
Considering this inverse correlation between selectivity and solubility, a single-step batch-fractionation process was designed
to increase the 22:6 ethyl ester content from an initial value of 17.5% in the starting material to 55% in the final extract. 相似文献
994.
Min-Jae Yoon Yoan-Sang Bae Sang-Ha Son Jae-Wook Lee Chang-Ha Lee 《Korean Journal of Chemical Engineering》2007,24(5):877-880
Luminescent yttrium aluminum garnet (YAG, Y3Al5O12) nanoparticles doped with Eu (10 at%) were synthesized in batch-type and continuous-type supercritical water (SCW) reactors.
In the case of the continuous-type SCW method, the particles of YAG: Eu phosphors were much smaller and demonstrated a uniform
spherical-like shape. Inversely, in the case of the batch-type SCW method, a needle-like or elliptical-like shape was formed
because a finite amount of time was required to reach SCW conditions from ambient conditions. However, the emission intensity
of YAG: Eu phosphors synthesized by using the batch-type SCW method was stronger. Therefore, it is concluded that the continuous-type
SCW method is superior to the batch-type SCW method from the viewpoint of the particle size and shape, but the luminescence
property of phosphors in the continuous-type SCW method needs to be improved. In addition, a calcination process slightly
improved the luminescence intensities of YAG: Eu phosphors generated by using either the batch-type or continuous-type SCW
methods. 相似文献
995.
996.
增韧聚丙烯三元共混体阻燃性能的研究 总被引:3,自引:0,他引:3
研究了多种阻燃剂,包括Sb2O3、Al(OH)3、CPC、DBDPO对聚丙烯/高密度聚乙烯/乙丙橡胶(PP/HDPE/EPR)三元共混体—增韧聚丙烯—阻燃性能的影响;阻燃剂间的协同作用;并探讨了阻燃机理。结果表明:1、AL(OH)3的重量含量超过40%时,阻燃效果显著;2、三种阻燃剂(Sb2O3、DBDPO、CPE)并用,阻燃效果明显提高,含卤化合物(DBDPO与CPE)是Sb2O3重量的四倍时,阻燃性能最佳;3、Sb2O3与DBDPO并用时,当Br/Sb的摩尔比为3∶1时阻燃效果最好 相似文献
997.
The detergency profiles of sodium salt α-sulfonated methyl esters derived from palm stearin (α-SMEPS) and polyoxyethylene
(20) sorbitan monoesters (POESE) in mixed micelle systems were evaluated as a function of the weight ratios of α-SMEPS/POESE
[polyoxyethylene (20) sorbitan monolaurate (12), polyoxyethylene (20) sorbitan monostearate (18∶0), and polyoxyethylene (20)
sorbitan monooleate (18∶1)] at different water hardness values (5.12, 51.2, and 512.0 ppm CaCO3) and temperatures (20, 30, 45, and 65°C), respectively. All the mixtures of α-SMEPS/POESE (12, 18∶0, and 18∶1) systems exhibited
a synergistic effect at 65°C in the absence of hardness. This was evaluated by measuring the percentage of soil removed. The
systems showed an increase in detergency with both the temperature and water hardness. Maximal detergency was observed with
5.12 ppm CaCO3 in the mixed surfactant solution. 相似文献
998.
C4+ and S4+-codoped titanium dioxide (TiO2) having a rutile phase was prepared. By doping C4+ and S4+ ions into a TiO2 lattice, the absorption edge of rutile TiO2 powder was largely shifted from 400 to 700 nm. 2-Methylpyridine and methyleneblue were photocatalytically oxidized at high efficiency on C4+ and S4+-doped TiO2 under visible light at a wavelength longer than 5 nm. 相似文献
999.
Amanda D’Cruz Mangesh G. Kulkarni Lekha Charan Meher Ajay K. Dalai 《Journal of the American Oil Chemists' Society》2007,84(10):937-943
A series of alkali metal (Li, Na, K) promoted alkali earth oxides (CaO, BaO, MgO), as well as K2CO3 supported on alumina (Al2O3), were prepared and used as catalysts for transesterification of canola oil with methanol. Four catalysts such as K2CO3/Al2O3 and alkali metal (Li, Na, K) promoted BaO were effective for transesterification with >85 wt% of methyl esters. ICP-MS analysis
revealed that leaching of barium in ester phase was too high (~1,000 ppm) when BaO based catalysts were used. As barium is
highly toxic, these catalysts were not used further for transesterification of canola oil. Optimization of reaction conditions
such as molar ratio of alcohol to oil (6:1–12:1), reaction temperature (40–60 °C) and catalyst loading (1–3 wt%) was performed
for most efficient and environmentally friendly K2CO3/Al2O3 catalyst to maximize ester yield using response surface methodology (RSM). The RSM suggested that a molar ratio of alcohol
to oil 11.48:1, a reaction temperature of 60 °C, and catalyst loading 3.16 wt% were optimum for the production of ester from
canola oil. The predicted value of ester yield was 96.3 wt% in 2 h, which was in agreement with the experimental results within
1.28%. 相似文献
1000.
端氨基聚脲聚氨酯环氧树脂体系的固化反应及粘接性能 总被引:2,自引:0,他引:2
本文采用DTA和FT-IR研究了端氨基聚脲聚氨酯固化环氧树脂的反应特性,考察了被粘表面状态、偶联剂和促进剂、填料等对剪切强度性能的影响。并对该粘合剂耐化学腐蚀性进行了试验,说明具有好的耐腐蚀性。 相似文献