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1.
Metal-Free,Visible-Light-Induced Selective C−C Bond Cleavage of Cycloalkanones with Molecular Oxygen
Hong Xin Prof. Dr. Xin-Hua Duan Dr. Le Liu Prof. Dr. Li-Na Guo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(51):11690-11694
A metal-free, visible-light-induced oxidative C−C bond cleavage of cycloketones with molecular oxygen is described. Cooperative Brønsted-acid catalysis and photocatalysis enabled selective C−C bond cleavage of cycloketones to generate an array of γ-, δ- and ϵ-keto esters under very mild conditions. Mechanistic studies indicate that singlet molecular oxygen (1O2) is responsible for this transformation. 相似文献
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Hao-Hua Deng Guang-Wen Li Ai-Lin Liu Wei Chen Xin-Hua Lin Xing-Hua Xia 《Mikrochimica acta》2014,181(9-10):911-916
We demonstrate a sensitive and rapid colorimetric assay for selective detection of copper ions based on the strong coordination between Cu(II) ions and the tetrahydroxyaurate anions [Au(OH)4]? on the surface of thermally treated bare gold nanoparticles (GNPs). The method for making the unmodified GNPs is simple and results in a nanomaterial with a highly specific response to Cu(II). The thermal treatment of the bare GNPs and the recognition of Cu(II) ions is accomplished in a single step within 5 min. The presence of Cu(II) causes the color to change from red to purple-blue. The limit of detection (LOD) is 0.04 μM of Cu(II) when using UV–vis spectrometry and ratioing the absorbances at 650 and 515 nm, respectively. The method also is amenable to bare eye (visual) inspection and in this case has an LOD of 2.0 μM of Cu(II). Figure
Due to the strong coordination of Cu(II) ions with the tetrahydroxyaurate anions [Au(OH)4]- on the thermally treated bare GNPs, Cu(II) can directly induce the aggregation of the GNPs, resulting in an obvious color change from wine-red to purple-blue. 相似文献
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本研究在实验室自制的线形数字离子阱质量分析器上,通过改变数码电源的频率扫描方式,在CID过程中,通过扫描数字束缚方波电源的频率和数字激发方波的频率实现母体解离。例如对于利血平母体离子,当将离子数字束缚方波频率从500 kHz扫描到560 kHz,可以测量到低质荷比的碎片离子,成功实现了串级质谱分析的低质量碎片离子的分析。通过与利血平三重四极质谱串级质谱分析实验结果的比较,发现可以在数字离子阱质谱仪上获得与三重四极质谱相同的串级质谱测量结果。结果表明,本方法可以用于低质量离子的测量,克服了传统离子阱质谱进行串级质谱分析的一个主要难点,显著提高数字离子阱质谱的性能。 相似文献
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A new luminescent Zn(II) compound, [Zn(pbdc)0.5(mtz)(DMPU)]n(1, H2pbdc = terephthalic acid, Hmtz = 5-methyl-1H-tetrazole, DMPU = N,N'-dimethylpropyleneurea), has been urothermally synthesized and characterized by elemental analysis, IR, X-ray powder diffraction(PXRD) and single-crystal X-ray diffraction. The title compound crystallizes in orthorhombic Pbca space group with a = 17.2649(5), b = 10.4680(3), c = 17.4457(7) ?, V = 3152.94(18) ?3, C12H17N6O3Zn, Mr = 358.71, Z = 8, Dc = 1.511 g/cm3, F(000) = 1480, μ = 1.579 mm-1, the final R = 0.0379 and wR = 0.0971 for 2785 observed reflections(I 2?(I)). Single-crystal X-ray structural analysis reveals that compound 1 features a 2D undulated layer with a 3-connected hcb topology. Moreover, the luminescent properties of 1 have also been investigated in the solid-state at room temperature. 相似文献
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Open-circuit voltage analysis of p-i-n type amorphous silicon solar cells deposited at low temperature 下载免费PDF全文
This paper identifies the contributions of p-a-SiC:H layers and i-a-Si:H layers to the open circuit voltage of p-i-n type a-Si:H solar cells deposited at a low temperature of 125 C.We find that poor quality p-a-SiC:H films under regular conditions lead to a restriction of open circuit voltage although the band gap of the i-layer varies widely.A significant improvement in open circuit voltage has been obtained by using high quality p-a-SiC:H films optimized at the "low-power regime" under low silane flow rates and high hydrogen dilution conditions. 相似文献
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The tearing mode instability plays a key role in the triggering process of reconnection. The triggering collisionless tearing mode instability has been theoretically and numerically analyzed by many researchers. However, due to the difficulty in obtaining the observational wave number, it is still unknown whether the tearing mode instability can be excited in an actual plasma sheet prior to reconnection onset. Using the data from four Cluster satellites prior to a magnetospheric reconnection event on 13 September 2002, we utilized the wave telescope technique to obtain the wave number which corresponds to the peak of power spectral density. The wavelength is about 18RE and is consistent with previous theoretic and numerical results. After substituting the wave vector and other necessary parameters of the observed current sheet into the triggering condition of tearing mode instability, we find that the near-Earth current sheet prior to reconnection is unstable to tearing mode. 相似文献
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用2,4,6-吡啶三甲酸和稀土钐、镝或钆的高氯酸盐溶液、碳酸锶、碳酸钾在180℃水热条件下进行反应,制备出3个含有3种金属离子的配位聚合物[LnSrK(ptc)2(H2O)]n(Ln=Sm(1)、Dy(2)、Gd(3),H3ptc=2,4,6-吡啶三甲酸)。X射线单晶衍射分析表明三者具有相同的结构,属三斜晶系,P1空间群。配合物中配体2,4,6-吡啶三甲酸根以2种不同的配位方式与3种金属离子配位,一种方式中连接了7个金属离子,另一种方式中连接了8个金属离子。Ln(Ⅲ)为八配位,与羧基上的6个氧原子和2个吡啶环上的2个氮原子配位;Sr(Ⅱ)也是八配位,配位原子均为氧原子;K(I)与5个氧原子配位。荧光发射光谱表明,钐和镝的配合物在紫外光激发下均发射Sm(Ⅲ)和Dy(Ⅲ)两种离子的特征荧光,钆的配合物在紫外光激发下由于发生荷移跃迁而发射绿色荧光。 相似文献
10.
A visible-light-induced palladium-catalyzed Dowd–Beckwith ring expansion/C–C bond formation cascade is described. A range of six to nine-membered β-alkenylated cyclic ketones possessing a quaternary carbon center were accessed under mild conditions. Besides styrenes, the electron-rich alkenes such as silyl enol ethers and enamides were also compatible, providing the desired β-alkylated cyclic ketones in moderate to good yields.An intermolecular Dowd–Beckwith ring expansion/C–C bond formation is achieved through light-induced palladium catalysis. Not only styrenes but also the electron-rich alkenes such as silyl enol ethers and enamides were also compatible in this reaction. 相似文献