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861.
862.
Rapid motion capture of phase-controlled wave packets was realized using a sensitive wave-packet spectrometer, which was previously developed by the present authors. Two-dimensional Fourier-transformed spectrograms obtained by the wave-packet spectrometer provide us full information about the wave-packet motion on both excited- and ground-state potential surfaces. Vibrational wave packet associated with a twisting mode in a DTTCI molecule was observed to be dependent on the pulse chirp, and was generated in the excited state preferably with negatively chirped excitation. The result indicates that the excited-state wave packet can be driven along a favorable configuration coordinate by using phase-controlled femtosecond pulses. The present method is essential to adaptive coherent-control application. 相似文献
863.
Oehlke A Auer AA Jahre I Walfort B Rüffer T Zoufalá P Lang H Spange S 《The Journal of organic chemistry》2007,72(12):4328-4339
A series of stilbeneboronate pinacol cyclic esters, containing none to three nitro groups, have been synthesized by various olefination reactions and characterized by X-ray single-crystal structure analysis. A stilbeneboronate ester bearing electron-acceptor groups experiences transition to a push-pull pi-electron system upon complexation with one fluoride ion at the boron atom. The UV-vis absorption maxima of the presented nitro-substituted stilbeneboronate esters are red-shifted upon addition of fluoride ions, indicating this binding event. The enhancement of the polarity of the investigated compounds and the changes in the electronic system were investigated by UV-vis absorption spectroscopy and solvatochromism. Additionally, studies were performed by natural bond orbital (NBO) analysis and RI-CC2 calculations of the vertical excitation energies. The synergism of fluoride ion complexation and solvation upon the UV-vis band shift is interpreted in terms of linear solvation energy relationships (LSERs) using the Kamlet-Taft solvent parameter set. It is found that the UV-vis absorption of the fluoro-boronates is strongly dependent on the solvents hydrogen-bond donating ability. 相似文献
864.
Yang Zhou Dr. Wei Xi Zixin Xie Zhixin You Xunzhu Jiang Bing Han Dr. Rui Lang Prof. Dr. Chuande Wu 《化学:亚洲杂志》2021,16(18):2622-2625
Single-atom catalysis has become a new branch in heterogeneous catalysis. Although the naturally produced SiO2-based materials are abundant and stable, fabrication of single-atom catalysts on such supports with high loading remains as a formidable challenge due to the lack of bonding sites to anchor the isolated metal species. Herein, modifying the diatomite, a kind of pure SiO2 mineral, with CeO2 nanoparticles is demonstrated to increase the defect sites on the support. The enhanced metal-support interaction maintains the atomic dispersion of Pt species with above 1 wt.% loading, exhibiting good performance in the selective hydrogenation of phenylacetylene to styrene. 相似文献
865.
以天然高分子阿拉伯树胶(AG)为还原剂和稳定剂制备了金纳米粒子;将含有金纳米粒子(Au NPs)、阿拉伯树胶和氨水的溶液滴加到乙醇中形成AG-Au NPs复合胶团;利用正硅酸乙酯水解,在AG-Au NPs表面包覆二氧化硅壳层;通过简单水洗的方法得到了金纳米粒子@二氧化硅(Au@SiO_2)中空微球.采用透射电子显微镜(TEM)、X射线衍射仪(XRD)和氮气吸附实验等对Au@SiO_2中空微球进行表征.通过设计对比实验,证实阿拉伯树胶在中空结构形成过程中起到模板剂的作用.催化性能测试结果表明,所制备的Au@SiO_2中空微球在硼氢化钠还原亚甲基蓝的反应中表现出良好的催化活性和重复使用性. 相似文献
866.
Ling-Yang Liu Xu Zhang Hong-Xia Li Bao Liu Jun-Wei Lang Ling-Bin Kong Xing-Bin Yan 《中国化学快报》2017,28(2):206-212
Li-ion hybrid capacitors (LIHCs), composing of a lithium-ion battery (LIB) type anode and a supercapacitor (SC) type cathode, gained worldwide popularity due to harmonious integrating the virtues of high energy density of LIBs with high power density of SCs. Herein, nanoflakes composed microflower-like Co-Ni oxide (CoNiO) was successfully synthesized by a simple co-precipitation method. The atomic ratio of as-synthesized CoNiO is determined to be 1:3 through XRD and XPS analytical method. As a typical battery-type material, CoNiO and capacitor-type activated polyanilinederived carbon (APDC) were used to assemble LIHCs as the anode and cathode materials, respectively. As a result, when an optimized mass ratio of CoNiO and APDC was 1:2, CoNiO//APDC LIHC could deliver a maximum energy density of 143 Wh kg-1 at a working voltage of 1-4 V. It is worth mentioning that the LIHC also exhibits excellent cycle stability with the capacitance retention of 78.2% after 15,000 cycles at a current density of 0.5 A g-1. 相似文献
867.
A green protocol for the synthesis of quinoxalines has been developed from catalytic oxidative cyclization of deoxybenzoins with 1,2-phenylenediamines in water.The optimal conditions are involved in the use of a water-soluble mononuclear copper(Ⅱ) complex of a zwitterionic calix[4]arene[Cu(Ⅱ)LCH_2O)]I_2(1,H_4L=[5,ll,17,23-tetrakis(trimethylammonium)-25,26,27,28-tetrahydroxycalix[4]arene]) as a catalyst in alkali solution after refluxing for 15 h in O_2.The target quinoxaline and its derivatives were obtained in good yields(up to 88%).The procedure described in this paper is simple,practical and environmentally benign. 相似文献
868.
869.
A. A. M. Aly S. Z. Vatsadze B. Walfort T. Rüffer H. Lang 《Russian Journal of Inorganic Chemistry》2017,62(12):1584-1594
The reaction of the silver salts AgX (a: X = BF4-, b: X = ClO4-, c: X = OTf–) with α,α'-di(3/4-pyridylmethylene)cycloalkanones (L1–L3) and piperidones (L4–L7) results in the formation of coordination products of general composition [AgX(L n )(solvent)] and [AgX(L n )] (L n = L1–L7). All complexes were characterized by elemental analysis and IR-spectroscopy. The structures of [Ag(ClO4)(L1)(MeC≡N)]∞ (1b · MeC≡N) and [Ag(ClO4)(L1)]∞ (1b) in the solid state are reported. In both structures {Ag(L1)}+ building units are linked to each other via Ag–Npyridine primary bonds resulting in the formation of infinite chains. In both structures the ligands L1 are fixed in transoid conformations, thus forming zig-zag polar chains. The structure of 1b · MeC≡N consists of pairs of tightly and loosely stacked chains. The tightly packed chains are weakly coupled by perchlorate anions acting as μ-bridges in between Ag(I) centers as well as by π–π-stacking interactions of unsaturated fragments of the respective ligands. In contrast, polar 2D layers composed of {Ag(L1)} m m+ chains, which interdigitate via multiple weak interactions by Ag–O contacts, are found in the solid structure of 1b. The dissolution of coordination products in coordinating solvents like MeCN or DMSO leads to the decomposition of complexes due to formation of silver-solvent coordination compounds. The coordination products 1–5 are stable in solid state against exposure to the ambient light, whereas solutions of the compounds, especially in DMSO-d6, appeared to be photochemically labile. As revealed by NMR spectroscopic studies, the organic components undergo trans-cis isomerization. 相似文献
870.
Shi-Yuan Liu Lin-Yan Xu Chun-Yu Liu Zhi-Gang Ren David James Young Jian-Ping Lang 《Tetrahedron》2017,73(17):2374-2381
An efficient catalytic system containing [RuCl2(η6-p-cymene)]2 and one P,N ligand, N-diphenylphosphino-2-aminopyridine (L1) was loaded in catalyzing the alkylation of ketones with primary alcohols for a diverse array of substrates. Other five P,N ligands based on pyridin-2-amine and pyrimidin-2-amine were also examined in this reaction to explore the influence of steric hindrance and electronic effects. Monitoring by 1H NMR and ESI-MS reveals a stable cationic L1-coordinated ruthenium hydride intermediate, identified as [Ru(η6-p-cymene)(κ2-L1)H]+. Organic intermediates consistent with a three-step dehydrogenation, alkylation and hydrogenation pathway were also observed. The final step in this reaction, the ruthenium-catalysed transfer hydrogenation reduction of α,β-unsaturated ketone with benzyl alcohol was performed separately. 相似文献