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51.
52.
Water splitting is considered a promising approach for renewable and sustainable energy conversion. The development of water splitting electrocatalysts that have low-cost, long-lifetime, and high-performance is an important area of research for the sustainable generation of hydrogen and oxygen gas. Here, we report a metal-free porphyrin-based two-dimensional crystalline covalent organic polymer obtained from the condensation of terephthaloyl chloride and 5,10,15,20-tetrakis(4-aminophenyl) porphyrin which is stabilized by an extensive hydrogen bonding network. This material exhibits bifunctional electrocatalytic performance towards water splitting with onset overpotentials, η, of 36 mV and 110 mV for HER (in 0.5 M H2SO4) and OER (in 1.0 M KOH), respectively. The as-synthesized material is also able to perform water splitting in neutral phosphate buffer saline solution, with 294 mV for HER and 520 mV for OER, respectively. Characterized by electrochemical impedance spectroscopy (EIS) and chronoamperometry, the as-synthesized material also shows enhanced conductivity and stability compared to its molecular counterpart. Inserting a non-redox active zinc metal center in the porphyrin unit leads to a decrease in electrochemical activity towards both HER and OER, suggesting the four-nitrogen porphyrin core is the active site. The high performance of this metal-free material towards water splitting provides a sustainable alternative to the use of scarce and expensive metal electrocatalysts in energy conversion for industrial applications.Water splitting is considered a promising approach for renewable and sustainable energy conversion. 相似文献
53.
研究了新显色剂长链饱和脂肪烃取代基化合物 (UPT)和微量 Cu2 反应。试验表明 ,在p H5.2~ 5.6的乙酸 -乙酸钠介质中 ,Cu2 与试剂形成摩尔比为 1∶ 3的淡黄绿色稳定络合物 ,其最大吸收为 30 0 .4nm,表观摩尔吸光系数为 ε30 0 .4 nm=2 .39× 1 0 5L·mol-1·cm-1。铜浓度在 2~ 1 2 μg/2 5ml的范围内符合比耳定律 ,相关系数 r=0 .9990。方法简便、灵敏 ,应用于样品测定 ,结果满意 相似文献
54.
The Se‐Se bond in diselenides was reduced by CeCl3/Sm system to produce selenolate anions, which react with α,β‐unsaturated esters or α,β‐unsaturated nitriles to afford β‐selenoesters and β‐selenonitriles, respectively. 相似文献
55.
Wenlu Sun Congjia Zhou Yingzhu Fan Yulu He Dr. Hui Zhang Prof. Zhilong Quan Dr. Huabin Kong Prof. Fang Fu Prof. Jiaqian Qin Prof. Yanbin Shen Prof. Hongwei Chen 《Angewandte Chemie (International ed. in English)》2023,62(13):e202300158
Fast and continuous ion insertion is blocked in the common electrodes operating with widely accepted single-ion storage mechanism, primarily due to Coulomb repulsion between the same ions. It results in an irreconcilable conflict between capacity and rate performance. Herein, we designed a porous organic framework with novel multiple-ion co-storage modes, including PF6−/Li+, OTF−/Mg2+, and OTF−/Zn2+ co-storage. The Coulomb interactions between cationic and anionic carriers in the framework can significantly promote electrode kinetics, by rejuvenating fast ion carrier migration toward framework interior. Consequently, the framework via PF6−/Li+ co-storage mode shows a high energy density of 878 Wh kg−1 cycled more than 20 000 cycles, with an excellent power density of 28 kW kg−1 that is already comparable to commercial supercapacitors. The both greatly improved energy and power densities via the co-storage mode may pave a way for exploring new electrodes that are not available from common single-ion electrodes. 相似文献
56.
Yulu Yang Huaping Wang Chunlei Zhu Prof. Jianmin Ma 《Angewandte Chemie (International ed. in English)》2023,62(22):e202300057
Lithium metal batteries (LMBs) comprising Li metal anode and high-voltage nickel-rich cathode could potentially realize high capacity and power density. However, suitable electrolytes to tolerate the oxidation on the cathode at high cut-off voltage are urgently needed. Herein, we present an armor-like inorganic-rich cathode electrolyte interphase (CEI) strategy for exploring oxidation-resistant electrolytes for sustaining 4.8 V Li||LiNi0.6Co0.2Mn0.2O2 (NCM622) batteries with pentafluorophenylboronic acid (PFPBA) as the additive. In such CEI, the armored lithium borate surrounded by CEI up-layer represses the dissolution of inner CEI moieties and also improves the Li+ conductivity of CEI while abundant LiF is distributed over whole CEI to enhance the mechanical stability and Li+ conductivity compared with polymer moieties. With such robust Li+ conductive CEI, the Li||NCM622 battery delivered excellent stability at 4.6 V cut-off voltage with 91.2 % capacity retention after 400 cycles. The excellent cycling performance was also obtained even at 4.8 V cut-off voltage. 相似文献
57.
A number of structurally diverse amides were synthesized by reaction of the corresponding amines with benzoyl chloride under
microwave irradiation. The proposed procedure ensures short reaction time, high yields, and excellent selectivity and considerably
broadens the series of amines as compared to the microwave-assisted synthesis of amides directly from carboxylic acids. It
can also be used for selective protection of various amines, including aromatic, aliphatic, and heterocyclic.
Published in Russian in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 3, pp. 365–368.
The text was submitted by the authors in English. 相似文献
58.
CuO/γ—Al2O3上CO和NO吸附的红外光谱研究:Ⅱ.还原态 总被引:1,自引:0,他引:1
应用红外光谱技术研究了CO和NO及其混合气体在还原态CuO/γ-Al_2O_3上的吸附.XRD分析样品物相仅有Cu~0,但是,XPS和IR都证明样品表面上除Cu~0外,还有Cu~(2+)和Cu~+。CO以分子态的形式吸附在Cu~+和Cu~0上(低于173K,无NO存在时,CO可以吸附在Cu~(2+)上);NO以分子态吸附在Cu~(2+)上,在Cu~0上为离解吸附(173K以下,无CO存在时,NO可以吸附在Cu~+上)。CO吸附时,表面还生成HCO_3~-、CO_3~(2-)、HCOO~-,NO吸附时,除被氧化为NO3~-外,表面上还出现N_2O物种;高于室温时,CO和NO共吸附,表面上除生成HCO_3~-、CO_3~(2-)和N_2O外,还有NCO~-物种生成,讨沦了CO和NO反应的基本步骤。 相似文献
59.
A new simple method for the preparation of bis (substituted phenyl) carbodiazone compounds (ArN=NCON=NAr) is reported. Nine of the compounds were synthesized by the oxidation of aryl substituted carbazide with ferric chloride in acid medium with good yield. 相似文献
60.
为满足C-ADS项目建设对超导轮辐腔Spoke021的需求,对Spoke021进行了详细的电磁参数优化。对Spoke021的参数化模型进行参数扫描,针对腔体的关键电磁特征量寻找可能存在的极值,详细分析、解释了优化过程中各个参数发生变化的物理意义。在Spoke021各参数达到最终优化值时,表征腔体性能的两个关键比值分别为:E_p/E_(acc)=3.14,Bp/E_(aCC)=4.77 mT/(MV/m)。考虑到次级电子倍增(Multipacting,MP)对Spoke021运行中所能达到的性能指标有很重要影响,对腔体的MP进行了建模分析。结果表明,当Spoke021工作在E_(acc)=10 MV/m情况下,没有发生MP,优化得到的参数可以满足Spoke021工程设计的需要;最后计算了腔体的TTF曲线,表明该腔体具有较宽的速度接受度。 相似文献