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991.
含蒽酰亚胺基团的化合物N-(2-(6-氨基吡啶))-9-蒽酰亚胺(L1)对Fe3+表现出灵敏的荧光增强响应.L1的衍生物N,N-′(2,6-吡啶基)-二(9-蒽酰亚胺)(L2)对Hg2+在紫外-可见吸收光谱和荧光光谱上显示了良好的识别性.即使在其它金属阳离子存在下,L1和L2分别对于Fe3+和Hg2+仍然表现出较好的选择性. 相似文献
992.
Ag-Cu双金属纳米颗粒在硅酸盐玻璃中的形成过程 总被引:1,自引:0,他引:1
利用两步离子交换结合H2气氛热处理的方法,制备出Ag-Cu双金属纳米颗粒/硅酸盐玻璃复合材料.结合吸收光谱和X射线光电子能谱研究了不同工艺条件下Ag、Cu在玻璃中的深度分布、价态变化及其玻璃网络结构的变化.结果表明:掺杂后的玻璃中银和铜的含量随深度不同有所不同.Ag+-Na+离子交换过程中,Ag+与非桥氧结合形成Si-O-Ag键,样品中的银主要以离子状态存在.H2气氛中热处理后,大部分与非桥氧相连的Ag+被还原,H+随即取代Ag+位置,与非桥氧形成-OH结构,还原出来的Ag0经成核和生长形成银纳米颗粒.第二次Cu+-Na+离子交换后,Cu+被引入硅酸盐玻璃,并有二价铜离子存在,再经过H2热处理后,铜离子被还原,在表层聚集生成铜纳米颗粒. 相似文献
993.
Progress in the use of ATR-IR spectroscopy to improve the understanding of liquid-phase heterogeneous catalytic reactions
is illustrated using the example of the oxidation of benzyl alcohol over Pd/Al2O3 and Bi–Pd/Al2O3. The in situ studies performed in both batch and continuous reactor cells provide rich information on the reaction pathway
and important facets of the mechanism, such as the nature of active Pd sites and the effect of the Bi-promoter. The combination
of CO site blocking prior to reaction and isotopic labeling suggests that alcohol dehydrogenation occurs uniformly over Pd
nanoparticles, but only selected sites may allow desorption of the product benzaldehyde thus providing the required selectivity.
Promotion of Pd/Al2O3 using bismuth produces infrared spectra free of adsorbed CO. This information demonstrates that Bi is deposited on selected
adsorption sites (terraces rather than defects) and simultaneously confirms that open terraces favor product decomposition.
Experiments performed in the continuous reactor cell using different catalyst film thickness show that reactions can be studied
under kinetic or mass transfer limited conditions depending on catalyst film thickness. This allowed to study the alcohol
oxidation under conditions of oxygen diffusion limitation, which are preferably applied in praxis in order to prevent catalyst
deactivation by over-oxidation. 相似文献
994.
Soraya Handjani Stanislaw Dzwigaj Juliette Blanchard Eric Marceau Jean-Marc Krafft Michel Che 《Topics in Catalysis》2009,52(4):334-343
Differences between the acidic properties of silicoaluminic Pt-containing catalysts and those assessed on their parent supports have been reported in the literature and attributed to the presence of the metal nanoparticles and to their influence on the acid sites. It is shown here that for mesoporous materials containing various types of Al species, an alternative explanation can be proposed. 27Al NMR spectroscopy, FTIR of adsorbed CO and probe catalytic tests suggest the redistribution of aluminium atoms upon contact of the parent support with the aqueous solution containing the Pt precursor. Upon contact with water and thermal treatment, strong and mild Brønsted sites (Si–O(H)–Al) transform into strong Lewis sites (isolated tetracoordinated Al atoms). As a consequence, it may not be straightforward to deduce the acidic properties of metal-containing catalysts supported on Al-containing mesoporous materials from those of the bare support, because the surface species may differ significantly. 相似文献
995.
996.
健那绿(Janus Green B,JGB)与核酸形成离子性缔合物增溶于混合非离子性表面活性剂中,导致吸光度降低,降低程度与加入的核酸浓度成线性关系,在最佳反应条件下,小牛胸腺DNA(ctDNA)、鱼精子DNA(fsDNA)及酵母RNA(yRNA)的线性范围分别为0.0~4.2μg/mL,0.0~2.4μg/mL及0.0~1.9μg/mL,检测限分别为ctDNA:57ng/mL,fsDNA:96ng/mL及yRNA:42ng/mL,用双倒数直线方程求出各种核酸与JGB的结合常数,均为10^4数量级,本法已用于实际样品分析。 相似文献
997.
铽-聚N-乙烯基乙酰胺-1,10-菲罗啉三元配合物的光学性能 总被引:1,自引:0,他引:1
以N乙烯基乙酰胺(NVA)为原料通过自由基聚合反应合成了N乙烯基乙酰胺(PNVA),在乙醇溶液中合成了铽聚N乙烯基乙酰胺1,10菲罗啉(TbPNVAphen)的三元稀土高分子配合物。利用FTIR、UV-vis和荧光光谱对三元配合物进行了结构表征。荧光光谱表明,配合物的最佳激发波长为304nm;在此波长激发下,配合物在490nm和546nm处发出较强铽的特征荧光,荧光强度分别为846.853和2086.798,分别比TbPNVA配合物增强了1310%和1290%。 相似文献
998.
PE微观结构的红外光谱实用表征 总被引:7,自引:0,他引:7
利用傅里叶变换红外光谱(FTIR)研究了多种类型以及与不同α-烯烃共聚合的聚乙烯(PE),发现采用FTIR差谱技术可对共聚PE的结构类型定性分析。通过比较甲基1378cm^-3处和亚甲基1369cm^-3处的峰强以及比较不饱和基团在908cm^-1和888cm^-1处的峰强.并分析700~900cm^-1的支链吸收峰.可分别获得判断PE类型及共聚PE结构的信息。此外,通过测算l378cm^-1处的峰强.建立了共聚PE支化度的定量分析曲线。 相似文献
999.
Mariusz Trytek Jan Fiedurek Katarzyna Polska Stanisław Radzki 《Catalysis Letters》2005,105(1-2):119-126
A photoexcited porphyrin system has been found to be an efficient catalyst for D-limonene biotransformation. The catalyst showed high selectivity in hydroxylation of D-limonene. The best catalyst for limonene biotransformation was 5,10,15,20-Tetraphenylporphyrin (H2TPP), which gave the highest accumulation of carvone and an unknown product with a verbenone-like mass spectrum. The highest
conversion yield of these products was favoured at 1:2 molar ratio of H2TPP to limonene. Some factors affecting the biotransformation yield were also investigated. Maximal yield of carvone was obtained
in the medium containing 90% of the substrate, within the period of 18–36 h. Mechanism involved in limonene biotransformation
catalysed by H2TPP is also discussed. 相似文献
1000.
C.?M.?SeubertEmail author M.?E.?Nichols A.?V.?Kucherov 《Journal of Coatings Technology and Research》2005,2(7):529-538
The long-term weathering performance of two UV-curable clearcoat systems was studied using in-plane microtomy in combination
with infrared spectroscopy, UV spectroscopy, and ESR spectroscopy. Oxygen transport characteristics were also studied using
the half-time method. The photooxidation versus depth profile was highly dependant on the presence of hindered amine light
stabilizers (HALS) for both coating systems. Ultraviolet light absorbers (UVA) had little effect on the photooxidation profile.
A photooxidation gradient was formed in both clearcoats due to a reduction in oxygen solubility when compared to standard
thermoset clearcoats. This gradient was only seen in formulations not containing HALS.
Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago,
IL. 相似文献