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排序方式: 共有2219条查询结果,搜索用时 249 毫秒
91.
Sarah R. Geenen Lysander Presser Dr. Torsten Hölzel Prof. Dr. Christian Ganter Prof. Dr. Thomas J. J. Müller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(36):8064-8075
Differently 5-substituted 8-methoxypsoralens can be synthesized by an efficient synthetic route with various cross-coupling methodologies, such as Suzuki, Sonogashira and Heck reaction. Compared to previously synthesized psoralens, thereby promising daylight absorbing compounds as potentially active agents against certain skin diseases can be readily accessed. Extensive investigations of all synthesized psoralen derivatives reveal fluorescence in the solid state as well as several distinctly emissive derivatives in solution. Donor-substituted psoralens exhibit remarkable photophysical properties, such as high fluorescence quantum yields and pronounced emission solvatochromicity and acidochromicity, which were scrutinized by Lippert–Mataga and Stern–Volmer plots. The results indicate that the compounds exceed the limit of visible light, a significant factor for potential applications as an active agent. In addition, (TD)DFT calculations were performed to elucidate the underlying electronic structure and to assign experimentally obtained data. 相似文献
92.
An ultrasound-assisted nanoscaled supramolecular coordination polymer (nanosized 1′ ) has been synthesized using a self-assembly reaction of K3[Cu (CN)4] and hexamethylenetetramine in the presence of Me3SnCl under ambient conditions. Nanosized 1′ was examined using elemental analysis, Fourier transform–infrared, transmission electron microscopy, scanning electron microscopy and X-ray powder diffractions. It was structurally compared with the single crystal supramolecular coordination polymer ∞3[Cu6(CN)7(C6H12N4)2(OH3)]; SCP 1. The photocatalytic activities of nanosized 1′ and SCP 1 toward different hazardous organic dyes were determined under ambient, UV-light irradiation and ultrasonic conditions. SCP 1 and nanosized 1′ as heterogeneous nanoparticles catalysts exhibited high catalytic activity for degradation of Congo Red, Methyl Violet 2B and Methylene Blue dyes. The effects of operational parameters on catalytic degradation process, identification of the degradation products and recycling of the catalyst were also investigated. SCP 1 and nanosized 1′ are recyclable heterogeneous catalysts and can be reused with efficient activities. The mechanism of degradation using different scavenger techniques iss proposed and discussed. The catalytic oxidation process is mainly caused by •OH radicals. 相似文献
93.
Dr. Boris Schade Dr. Abhishek Kumar Singh Dr. Virginia Wycisk Dr. Jose Luis Cuellar-Camacho Dr. Hans von Berlepsch Prof. Rainer Haag Dr. Christoph Böttcher 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(30):6919-6934
The syntheses of novel amphiphilic 5,5′,6,6′-tetrachlorobenzimidacarbocyanine (TBC) dye derivatives with aminopropanediol head groups, which only differ in stereochemistry (chiral enantiomers, meso form and conformer), are reported. For the achiral meso form, a new synthetic route towards asymmetric cyanine dyes was established. All compounds form J aggregates in water, the optical properties of which were characterised by means of spectroscopic methods. The supramolecular structure of the aggregates is investigated by means of cryo-transmission electron microscopy, cryo-electron tomography and AFM, revealing extended sheet-like aggregates for chiral enantiomers and nanotubes for the mesomer, respectively, whereas the conformer forms predominately needle-like crystals. The experiments demonstrate that the aggregation behaviour of compounds can be controlled solely by head group stereochemistry, which in the case of enantiomers enables the formation of extended hydrogen-bond chains by the hydroxyl functionalities. In case of the achiral meso form, however, such chains turned out to be sterically excluded. 相似文献
94.
Dr. Aron J. Huckaba Dr. Aswani Yella Dr. Louis E. McNamara April E. Steen J. Scott Murphy Casey A. Carpenter George D. Puneky Prof. Nathan I. Hammer Prof. Mohammad Khaja Nazeeruddin Prof. Michael Grätzel Prof. Jared H. Delcamp 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(43):15536-15542
Desirable components for dye‐sensitzed solar cell (DSC) sensitizers and fluorescent imaging dyes include strong donating building blocks coupled with well‐balanced acceptor functionalities for absorption beyond the visible range. We have evaluated the effects of increasing acceptor strengths and incorporation of dye morphology controlling groups on molar absorptivity and absorption breadth with indolizine donor‐based dyes. Indolizine‐based D –A and D –π–A sensitizers incorporating bis‐rhodanine, tricyanofuran (TCF), and cyanoacrylic acid functionalities were analyzed for performance in DSC devices. The TCF derivatives were also evaluated as near‐infrared (NIR)‐emissive materials with the AH25 emissions extending past 1000 nm. 相似文献
95.
《Comptes Rendus Chimie》2016,19(3):371-380
Manganese porphyrin has been supported onto multi-walled carbon nanotubes (Mn(TCPP)OAc@MWCNT) and characterized by powder X-ray diffraction, FT-IR, atomic absorption and UV–vis spectroscopy, field emission scanning electron microscopy (FE-SEM) and also thermogravimetric analysis (TGA). The TGA curve shows that the nanocatalyst was thermally stable up to almost 350 °C. This catalyst was found to be able to oxidize different synthetic textile dyes in aqueous media over a wide pH range at ambient temperature with tert-butyl hydroperoxide (TBHP) as the oxygen source. The influence of some important parameters such as the initial pH of the dye solution, temperature and concentration of the catalyst, the oxidant and the co-catalyst were investigated. Also, the ability of this heterogeneous catalyst to oxidize 2,6-dimethylphenol (with excellent selectivity for quinone (86%)) with TBHP in acetonitrile was evaluated. The separation and recycling of the catalyst is simple and the catalyst can be used several successive cycles without significant decrease in catalytic activity. 相似文献
96.
Solvent-Free Condensation of Methyl Pyridinium and Quinolinium Salts with Aldehydes Catalyzed by DBU
Methylpyridinium and methylquinolinium salts were condensed under solvent-free conditions with aromatic aldehydes in the presence of 1,8-diazabicyclo[5.4.]undec-7-ene (DBU) as catalyst, by grinding at room temperature. The products are dyes or useful intermediates. The DBU can be easily recycled and reused. 相似文献
97.
M. A. Hanna A. A. Al-Sarawy I. G. Rashed H. F. Elgamal F. K. M. Wali 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):2089-2108
A one mono and two disarylazo series of 1,2,4-benzothiadiazine-based dyestuffs has been synthesized with a view that these products, with their new all-round tinctorial properties, might find an application as new categories of direct dyes that satisfactorily replace prohibited benzidine-based dyes. The assigned structures for the hitherto prepared dyes were confirmed on the basis of elemental analysis as well as spectral data and, whenever possible, by alternative synthetic routes. Moreover, the predominant tautomeric structures for these highly colored products were tested and discussed on the basis of their spectral behavior. 相似文献
98.
《中国化学快报》2021,32(8):2359-2368
The photoisomerization properties of azo derivatives have been widely used in the fields of materials and biology.One serious restriction to the development of functional azo-based materials is the necessity to trigger switching by UV light,which damage the corresponding surfaces and penetrate only partially through the matter.Therefore,developing the visible and near-infrared light activated azo switches can solve this problem.This review provides a summary of molecular design strategies for driving the isomerization of azo derivatives with visible light and near-infrared light:(1) smart design directly excited by visible light,(2) the addition of upconversion nanoparticles,(3) the employment of twophoton absorption,(4) indirect excitation in combination with metal sensitizer. 相似文献
99.
《Mendeleev Communications》2021,31(6):807-809
Two new heptamethine cyanine dye–fullerene C60 covalently- linked dyads, which absorb in far-red and NIR spectral regions, have been synthesized by esterification click reaction and characterized by physicochemical methods. No significant fluorescence quenching was found due to weak electronic coupling between heptamethine moiety and fullerene core, which was confirmed by photophysical and electrochemical methods. Such dyads can be useful for cell imaging and fluorescence diagnostics of various fullerene derivatives. 相似文献
100.
Identification of Compounds that Selectively Stabilize Specific G‐Quadruplex Structures by Using a Thioflavin T‐Displacement Assay as a Tool 下载免费PDF全文
Dr. Jan Jamroskovic Dr. Madeleine Livendahl Dr. Jonas Eriksson Dr. Erik Chorell Dr. Nasim Sabouri 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(52):18932-18943
Small molecules are used in the G‐quadruplex (G4) research field in vivo and in vitro, and there are increasing demands for ligands that selectively stabilize different G4 structures. Thioflavin T (ThT) emits an enhanced fluorescence signal when binding to G4 structures. Herein, we show that ThT can be competitively displaced by the binding of small molecules to G4 structures and develop a ThT‐displacement high‐throughput screening assay to find novel and selective G4‐binding compounds. We screened approximately 28 000 compounds by using three different G4 structures and identified eight novel G4 binders. Analysis of the structural conformation and stability of the G4 structures in presence of these compounds demonstrated that the four compounds enhance the thermal stabilization of the structures without affecting their structural conformation. In addition, all four compounds also increased the G4‐structure block of DNA synthesis by Taq DNA polymerase. Also, two of these compounds showed selectivity between certain Schizosaccharomyces pombe G4 structures, thus suggesting that these compounds or their analogues can be used as selective tools for G4 DNA studies. 相似文献