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61.
The hydroboration of cis-2-butene and cis-3-hexene with pure diisopinocampheylborane (IPC2BH) and monoisopinocampheylborane (IPCBH2), both prepared from (+)-α-pinene, were studied. In contrast to IPC2BH, which yielded R-(?)-2-butanol and R-(?)-3-hexanol in 98.4 and 94.5% optical purities, IPCBH2 yielded S-(+)-2-butanol and S-(+)-3-hexanol in 23.6 and 19.7% optical purifies respectively. PMR examination of the methanolyzed products were utilized to establish the species present in the freshly prepared and aged 11 adduct from (+)-α-pinene and BH3 · THF. The results confirm the interpretation previously advanced for the major differences realized in asymmetric hydroboration with the fresh and aged 11 adducts.  相似文献   
62.
From the seeds of Phytolacca americana two new lignans, Americanin B and D, have been isolated and their structures elucidated mainly by spectroscopic methods  相似文献   
63.
3-(Pyrazolylhydrazonomethyl)-2-oxo-1, 2-dihydroquinoxalines were synthesized, and their tautomer ratios between hydrazone imine and diazenyl enamine forms were specified by pmr spectral data.  相似文献   
64.
    
The fascinating properties of single-layer graphene isolated by mechanical exfoliation have inspired extensive research efforts toward two-dimensional (2D) materials. Layered compounds serve as precursors for atomically thin 2D materials (briefly, 2D nanomaterials) owing to their strong intraplane chemical bonding but weak interplane van der Waals interactions. There are newly emerging 2D materials beyond graphene, and it is becoming increasingly important to develop cost-effective, scalable methods for producing 2D nanomaterials with controlled microstructures and properties. The variety of developed synthetic techniques can be categorized into two classes: bottom-up and top-down approaches. Of top-down approaches, the exfoliation of bulk 2D materials into single or few layers is the most common. This review highlights chemical and physical exfoliation methods that allow for the production of 2D nanomaterials in large quantities. In addition, remarkable examples of utilizing exfoliated 2D nanomaterials in energy and environmental applications are introduced.  相似文献   
65.
Alkylations of 4,5-dichloropyridazin-6-one (1) with dibromoalkanes 2 or 3 in the presence of potassium carbonate or tetrabutylammonium bromide/potassium hydroxide were investigated under restricted condition. Reactions of 1 with 2 or 3, except for 2b and 3b , in the presence of potassium carbonate or tetrabutylammonium bromide/potassium hydroxide gave only the N-alkylation products 3 and/or 4. Alkylation of 1 with 2b or 3b in the presence of potassium carbonate yielded the N-alkylation products 3b and/or 4b and the O-alkylation product 5 as the main product, whereas treatment of 1 with 2b or 3b in the presence of tetrabutylammonium bromide/potassium hydroxide afforded selectively the N-alkylation products 3b and/or 4b.  相似文献   
66.
In this research,the morphologies,isothermal-crystallization kinetics,and spherulite growth of aliphatic polyketone/polyamide-6 blends were studied.A single glass-transition temperature (Tg) was determined,and the composition dependence of Tg for these blends was well described by the Kwei equation.The strong intermolecular interaction between the two polymer components was confirmed by melting-point depression.The isothermal-crystallization kinetics were analyzed on the basis of the Avrami approach.A linear increase in the radii of the spherulites with time was observed for all compositions.All the spherulites continued to grow at nearly identical growth rates.With increasing polyamide-6 content,the size of the spherulites in the polyketone/polyamide-6 blends gradually decreased,and the number of spherulites in the blends increased.  相似文献   
67.
68.
    
Monitoring fluctuations in enzyme overexpression facilitates early tumor detection and excision. An AIEgen probe (DQM‐ALP) for the imaging of alkaline phosphatase (ALP) activity was synthesized. The probe consists of a quinoline‐malononitrile (QM) core decorated with hydrophilic phosphate groups as ALP‐recognition units. The rapid liberation of DQM‐OH aggregates in the presence of ALP resulted in aggregation‐induced fluorescence. The up‐regulation of ALP expression in tumor cells was imaged using DQM‐ALP. The probe permeated into 3D cervical and liver tumor spheroids for imaging spatially heterogeneous ALP activity with high spatial resolution on a two‐photon microscopy platform, providing the fluorescence‐guided recognition of sub‐millimeter tumorigenesis. DQM‐ALP enabled differentiation between tumor and normal tissue ex vivo and in vivo, suggesting that the probe may serve as a powerful tool to assist surgeons during tumor resection.  相似文献   
69.
    
Phototheranostic nanoplatforms are of particular interest for cancer diagnosis and imaging‐guided therapy. Herein, we develop a supramolecular approach to fabricate a nanostructured phototheranostic agent through the direct self‐assembly of two water‐soluble phthalocyanine derivatives, PcS4 and PcN4. The nature of the molecular recognition between PcS4 and PcN4 facilitates the formation of nanostructure (PcS4‐PcN4) and consequently enables the fabrication of PcS4‐PcN4 with completely quenched fluorescence and reduced singlet oxygen generation, leading to the high photoacoustic and photothermal activity of PcS4‐PcN4. In vivo evaluations suggest that PcS4‐PcN4 could not only efficiently visualize a tumor with high contrast through whole‐body photoacoustic imaging but also enable excellent photothermal therapy for cancer.  相似文献   
70.
The objective of this study was to assess the cytotoxicity of water-dispersible CuO nanoparticles by quantifying the reactive oxygen species (ROS)-related genes (glutathione S-transferase (GST) and catalase) using real-time polymerase chain reaction (RT-PCR). Monodisperse CuO nanoparticles of 14 nm in size were used. Cytotoxicity of CuO nanoparticles was evaluated under in vitro condition at different concentrations (10, 50, and 100 μg/ml) and incubation times (12, 24, and 48 h) with human cancer cell lines (breast cancer epithelial cells). The genetic level cytotoxic screening produced consistent results showing that GST and catalase ROS gene expression was maximized in 24 h incubation at 100 μg/ml concentration of CuO nanoparticles. However, the cytotoxicity of water-dispersible CuO nanoparticle was not significant compared with control experiments, demonstrating its high potential in the application of nanomedicines for a diagnostic and therapeutic tool.  相似文献   
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