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991.
Several anilino-pyridinium-type hemicyanines including flexible and bridged model compounds are compared using experimental and quantum chemical methods. The flexible compounds show broadened fluorescence band and exhibit strong fluorescence quenching connected with a barrierless viscosity-controlled transition from the planar to the perpendicular geometry. The latter is connected with a small S1–S0 and a vanishing S1–T1 energy gap, with charge localization and with forbidden emissive character. 相似文献
992.
蚊蝇杀灭器及其发射光谱分析 总被引:1,自引:0,他引:1
文章首先介绍了蚊蝇杀灭器在佛山市两个单位的职工饭堂厨房和会议室或值班室的试验情况。然后围绕文中四个图说明了下面四个问题:一,展示了进行光谱分析的测量装置。二,将蚊蝇杀灭器黑光灯的发射光谱和日用荧光灯发射光谱作分析比较。三,指出黑光灯也是一种荧光灯,说明了它的发光机理。四,展示了国外一种高效黑光灯的发射光谱,它是用活性铈钙磷酸脂做荧光涂料,我们进一步深入探讨了这种黑光灯的发光机制,并介绍了它的其他用 相似文献
993.
镧系离子(Eu3+,Tb3+)氧氟沙星配合物的合成和光谱表征 总被引:7,自引:2,他引:5
本文报道了镧系离子Eu3 + ,Tb3 + 同喹诺酮羧酸类衍生物氧氟沙星形成配合物的合成。用元素分析法和ICP确定了配合物的组成为Ln(oflo) 3 Cl3 ·8H2 O。红外光谱表明氧氟沙星配体羧基同中心离子发生螯合 ,并可能与邻位羰基形成六元环稳定结构。荧光光谱表明 ,Eu配合物具有很宽的激发谱带 (2 0 0~ 45 0nm) ,明显区别于其他羧酸类的稀土配合物 ;中心离子Eu3 + 发射谱位于 5 79 0nm(5D0 7F0 ) ,5 92 2nm(5D0 7F1) ,6 12 2nm(5D0 7F2 ) ;而Tb3 + 配合物则同时有配体和中心离子的荧光发射 相似文献
994.
995.
Nico A.J.M. Sommerdijk John D. Wright 《Journal of Sol-Gel Science and Technology》1998,13(1-3):565-568
Changes in the selectivity of molecular recognition systems on sol-gel entrapment are reported. Thermodynamic effects are exemplified by studies of the metal-ion complexing agent Eriochrome Cyanine R (ECR). In aqueous solution this binds strongly and selectively to Al3+, whereas in a TMOS-based sol-gel matrix it is selective for Cu3+. Thermodynamic effects, due to restricted translational freedom of water molecules or different solvent structure and isolation of ligands, can explain these observations. Effects of entrapment on molecular recognition by a large conformationally flexible molecule have been studied using a tris-terminated PAMAM dendrimer. The dendrimer conformation and its complexation with Cu2+ changes on entrapment, and binding of aromatic carboxylic acids such as ibuprofen can be detected by changes in visible absorption and surface plasmon resonance using spun films of the sol-gel composite. These effects show that in addition to providing a porous entrapment matrix of good optical quality, sol-gels may be used to alter the binding characteristics of the entrapped receptors. 相似文献
996.
黄应平 《新疆大学学报(理工版)》1997,14(4):75-77
研究了在表面活性剂存在下,三种新的9-取代苯基荧光酮类试剂与钼(Ⅵ)的显色反应及其光度分析特征,试验结果表明,试剂分子9位上引入的取代基明显影响试剂的配合能力。本文从取代基的电子效应等方面讨论了试剂的结构与性能之间的关系。 相似文献
997.
Joykrishna Dey A. Yvette Will Rezik A. Agbaria Peter W. Rabideau Atteye H. Abdourazak Renata Sygula Isiah M. Warner 《Journal of fluorescence》1997,7(3):231-236
The spectroscopic properties of corannulene and cyclopentacorannulene are examined by use of absorption and steady-state fluorescence
measurements. A red shift in the emission maxima of cyclopentacorannulene is noted with respect to the emission maxima in
the corannulene spectrum. Similar differences in the absorption spectra of both molecules are also observed. Reasons for the
dissimilarities in the absorption and emission spectra of these molecules are discussed. The fluorescence quantum yields and
lifetimes of the molecules measured in organic solvents are reported. The fluorescence quantum yield and lifetime of cyclopentacorannulene
are lower than those of corannulene. This difference is attributed to the highly strained and nonplanar structure of cyclopentacorannulene.
The effectiveness of nitromethane as a quencher of corannulene and cyclopentacorannulene fluorescence is examined. In contrast
to previously reported results, the fluorescence of these molecules is quenched by nitromethane. Fluorescence quenching of
the molecules has been attributed to complex formation in the ground state, i.e., static quenching. 相似文献
998.
样品中的有机碘高温灰化后,在酸性条件下,经饱和溴水将I^-氧化为IO3^-.在0.06%的磷酸酸度条件下,以KI还原KIO3,使样品中的碘放大六倍。系统优化选择了定波长、磷酸酸度、氯化钠质量浓度、淀粉用量、碘化钾用量等。在选定的最佳实验条件下,碘质量浓度在0~3.2μg/mL范围旱良好线性关系,相关系数为0.9995;方法榆出限为0.028μg/mL,回收率为96.27%~106.43%。 相似文献
999.
1000.
Karine Herreyre Denis Boudreau 《Spectrochimica Acta Part B: Atomic Spectroscopy》2004,59(12):1927-1933
The spectral background from 281 to 285 nm in the laser-enhanced ionization (LEI) spectrum of aqueous samples containing easily ionized elements (EIE) at concentrations similar to those found in blood was investigated. A complex, structured spectral background was observed, which appears in the presence of Na or K, but does not match the spectral signature of either element. The same behavior was also observed for Li. It was established that this background originates from an energy transfer between laser-excited hydroxyl (OH) molecules and ground-state EIEs. The intensity of this spectral feature was found to increase with EIE concentration and applied electrode voltage. This unexpected source of spectral interference may complicate the determination of trace metals by LEI in the presence of EIEs, since it can not be prevented by simply avoiding interference from atomic lines. 相似文献