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71.
A Bis(pyridine N‐oxide) Analogue of DOTA: Relaxometric Properties of the GdIII Complex and Efficient Sensitization of Visible and NIR‐Emitting Lanthanide(III) Cations Including PrIII and HoIII
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Henrique F. Carvalho Dr. João M. C. Teixeira Carlos T. B. Paula Prof. Petr Hermann Dr. Carlos Platas‐Iglesias Prof. Stephane Petoud Prof. Éva Tóth Prof. Carlos F. G. C. Geraldes 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(45):14834-14845
We report the synthesis of a cyclen‐based ligand (4,10‐bis[(1‐oxidopyridin‐2‐yl)methyl]‐1,4,7,10‐tetraazacyclododecane‐1,7‐diacetic acid= L1 ) containing two acetate and two 2‐methylpyridine N‐oxide arms anchored on the nitrogen atoms of the cyclen platform, which has been designed for stable complexation of lanthanide(III) ions in aqueous solution. Relaxometric studies suggest that the thermodynamic stability and kinetic inertness of the GdIII complex may be sufficient for biological applications. A detailed structural study of the complexes by 1H NMR spectroscopy and DFT calculations indicates that they adopt an anti‐Δ(λλλλ) conformation in aqueous solution, that is, an anti‐square antiprismatic (anti‐SAP) isomeric form, as demonstrated by analysis of the 1H NMR paramagnetic shifts induced by YbIII. The water‐exchange rate of the GdIII complex is ${k{{298\hfill \atop {\rm ex}\hfill}}}$ =6.7×106 s?1, about a quarter of that for the mono‐oxidopyridine analogue, but still about 50 % higher than the ${k{{298\hfill \atop {\rm ex}\hfill}}}$ of GdDOTA (DOTA=1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid). The 2‐methylpyridine N‐oxide chromophores can be used to sensitize a wide range of LnIII ions emitting in both the visible (EuIII and TbIII) and NIR (PrIII, NdIII, HoIII, YbIII) spectral regions. The emission quantum yield determined for the YbIII complex (${Q{{{\rm L}\hfill \atop {\rm Yb}\hfill}}}$ =7.3(1)×10?3) is among the highest ever reported for complexes of this metal ion in aqueous solution. The sensitization ability of the ligand, together with the spectroscopic and relaxometric properties of its complexes, constitute a useful step forward on the way to efficient dual probes for optical imaging (OI) and MRI. 相似文献
72.
Unraveling the Crystal Structure of Lanthanide–Murexide Complexes: Use of an Ancient Complexometry Indicator as a Near‐Infrared‐Emitting Single‐Ion Magnet
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Xiaohui Yi Dr. Kevin Bernot Vincent Le Corre Dr. Guillaume Calvez Dr. Fabrice Pointillart Dr. Olivier Cador Dr. Boris Le Guennic Julie Jung Dr. Olivier Maury Dr. Virginie Placide Dr. Yannick Guyot Dr. Thierry Roisnel Dr. Carole Daiguebonne Prof. Olivier Guillou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(6):1569-1576
Herein, we provide some structural evidence of the complexation color‐change of murexide solutions in presence of lanthanide, which has been used for decades in complexometric studies. For Ln=Sm to Lu and Y, the compounds crystallize as monomeric [Ln(Murex)3] ? 11 H2O with an N3O6 tricapped square‐antiprism environment, which are stable up to 250 °C. Single‐ion magnet (SIM) behavior is then observed on the YbIII derivative in an original nine‐coordinated environment. In‐field slow relaxation (Δ=(15.6±1) K; τ0=2.73×10?6 s) is observed with a very narrow distribution of the relaxation time (αmax=0.09). Magnetic and photophysical properties can be correlated. On one hand the analysis of NIR emission spectrum permits to have access to crystal field parameters and to compare them with those extracted from dc measurements. On the other hand, magnetic measurements permit to identify the nature of the M J states involved in the 2F5/2→2F7/2 luminescence spectrum. The gap between the low‐lying states is in agreement with the energy barrier obtained from magnetic slow‐relaxation measurement. 相似文献
73.
Two C3‐Symmetric Dy3III Complexes with Triple Di‐μ‐methoxo‐μ‐phenoxo Bridges,Magnetic Ground State,and Single‐Molecule Magnetic Behavior
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Dr. Mikko M. Hänninen Prof. Dr. Antonio J. Mota Dr. Daniel Aravena Prof. Dr. Eliseo Ruiz Prof. Dr. Reijo Sillanpää Dr. Agustín Camón Dr. Marco Evangelisti Prof. Dr. Enrique Colacio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(27):8410-8420
Two series of isostructural C3‐symmetric Ln3 complexes Ln3 ? [BPh4] and Ln3 ? 0.33[Ln(NO3)6] (in which LnIII=Gd and Dy) have been prepared from an amino‐bis(phenol) ligand. X‐ray studies reveal that LnIII ions are connected by one μ2‐phenoxo and two μ3‐methoxo bridges, thus leading to a hexagonal bipyramidal Ln3O5 bridging core in which LnIII ions exhibit a biaugmented trigonal‐prismatic geometry. Magnetic susceptibility studies and ab initio complete active space self‐consistent field (CASSCF) calculations indicate that the magnetic coupling between the DyIII ions, which possess a high axial anisotropy in the ground state, is very weakly antiferromagnetic and mainly dipolar in nature. To reduce the electronic repulsion from the coordinating oxygen atom with the shortest Dy?O distance, the local magnetic moments are oriented almost perpendicular to the Dy3 plane, thus leading to a paramagnetic ground state. CASSCF plus restricted active space state interaction (RASSI) calculations also show that the ground and first excited state of the DyIII ions are separated by approximately 150 and 177 cm?1, for Dy3 ? [BPh4] and Dy3 ? 0.33[Dy(NO3)6], respectively. As expected for these large energy gaps, Dy3 ? [BPh4] and Dy3 ? 0.33[Dy(NO3)6] exhibit, under zero direct‐current (dc) field, thermally activated slow relaxation of the magnetization, which overlap with a quantum tunneling relaxation process. Under an applied Hdc field of 1000 Oe, Dy3 ? [BPh4] exhibits two thermally activated processes with Ueff values of 34.7 and 19.5 cm?1, whereas Dy3 ? 0.33[Dy(NO3)6] shows only one activated process with Ueff=19.5 cm?1. 相似文献
74.
Hetero‐tri‐spin [2p‐3d‐4f] Chain Compounds Based on Nitronyl Nitroxide Lanthanide Metallo‐Ligands: Synthesis,Structure, and Magnetic Properties
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Mei Zhu Peng Hu Yungai Li Xiufeng Wang Prof. Licun Li Prof. Daizheng Liao V. M. L. Durga Prasad Goli Prof. S. Ramasesha Dr. Jean‐Pascal Sutter 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(41):13356-13365
Employing nitronyl nitroxide lanthanide(III) complexes as metallo‐ligands allowed the efficient and highly selective preparation of three series of unprecedented hetero‐tri‐spin (Cu?Ln‐radical) one‐dimensional compounds. These 2p–3d–4f spin systems, namely [Ln3Cu(hfac)11(NitPhOAll)4] (LnIII=Gd 1Gd , Tb 1Tb , Dy 1Dy ; NitPhOAll=2‐(4′‐allyloxyphenyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide), [Ln3Cu(hfac)11(NitPhOPr)4] (LnIII=Gd 2Gd , Tb 2Tb , Dy 2Dy , Ho 2Ho , Yb 2Yb ; NitPhOPr=2‐(4′‐propoxyphenyl)‐4,4,5,5‐tetramethyl‐imidazoline‐1‐oxyl‐3‐oxide) and [Ln3Cu(hfac)11(NitPhOBz)4] (LnIII=Gd 3Gd , Tb 3Tb , Dy 3Dy ; NitPhOBz=2‐(4′‐benzyloxyphenyl)‐4,4,5,5‐tetramethyl‐imidazoline‐1‐oxyl‐3‐oxide) involve O‐bound nitronyl nitroxide radicals as bridging ligands in chain structures with a [Cu‐Nit‐Ln‐Nit‐Ln‐Nit‐Ln‐Nit] repeating unit. The dc magnetic studies show that ferromagnetic metal–radical interactions take place in these hetero‐tri‐spin chain complexes, these and the next‐neighbor interactions have been quantified for the Gd derivatives. Complexes 1Tb and 2Tb exhibit frequency dependence of ac magnetic susceptibilities, indicating single‐chain magnet behavior. 相似文献
75.
Aptamer‐Based Luminescence Energy Transfer from Near‐Infrared‐to‐Near‐Infrared Upconverting Nanoparticles to Gold Nanorods and Its Application for the Detection of Thrombin
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Fei Yuan Prof. Dr. Hongqi Chen Juan Xu Yiyan Zhang Yong Wu Prof. Lun Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(10):2888-2894
A new luminescence energy transfer (LET) system has been designed for the detection of thrombin in the near‐infrared (NIR) region by utilizing NIR‐to‐NIR upconversion lanthanide nanophosphors (UCNPs) as the donor and gold nanorods (Au NRs) as the acceptor. The use of upconverting NaYF4:Yb3+,Tm3+ nanoparticles with sharp NIR emission peaks upon NIR excitation by an inexpensive infrared continuous wave laser diode provided large spectral overlap between the donor and the acceptor. Both the Au NRs and carboxyl‐terminated NaYF4:Yb3+,Tm3+ UCNPs were first modified with different thrombin aptamers. When thrombin was added, a LET system was then formed because of the specific recognition between the thrombin aptamers and thrombin. The LET system was used to monitor thrombin concentrations in aqueous buffer and human blood samples. The limits of detection for thrombin are as low as 0.118 nM in buffer solution and 0.129 nM in human serum. The method was also successfully applied to thrombin detection in blood samples. 相似文献
76.
Dr. Martín Regueiro‐Figueroa Dr. David Esteban‐Gómez Dr. Andrés de Blas Dr. Teresa Rodríguez‐Blas Dr. Carlos Platas‐Iglesias 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(14):3974-3981
The stability trends across the lanthanide series of complexes with the polyaminocarboxylate ligands TETA4? (H4TETA=2,2′,2′′,2′′′‐(1,4,8,11‐tetraazacyclotetradecane‐1,4,8,11‐tetrayl)tetraacetic acid), BCAED4? (H4BCAED=2,2′,2′′,2′′′‐{[(1,4‐diazepane‐1,4‐diyl)bis(ethane‐2,1‐diyl)]bis(azanetriyl)}tetraacetic acid), and BP18C62? (H2BP18C6=6,6′‐[(1,4,10,13‐tetraoxa‐7,16‐diazacyclooctadecane‐7,16‐diyl)bis(methylene)]dipicolinic acid) were investigated using DFT calculations. Geometry optimizations performed at the TPSSh/6‐31G(d,p) level, and using a 46+4fn ECP for lanthanides, provide bond lengths of the metal coordination environments in good agreement with the experimental values observed in the X‐ray structures. The contractions of the Ln3+ coordination spheres follow quadratic trends, as observed previously for different isostructural series of complexes. We show here that the parameters obtained from the quantitative analysis of these data can be used to rationalize the observed stability trends across the 4f period. The stability trends along the lanthanide series were also evaluated by calculating the free energy for the reaction [La( L )]n+/?(sol)+Ln3+(sol)→[Ln( L )]n+/?(sol)+La3+(sol). A parameterization of the Ln3+ radii was performed by minimizing the differences between experimental and calculated standard hydration free energies. The calculated stability trends are in good agreement with the experimental stability constants, which increase markedly across the series for BCAED4? complexes, increase smoothly for the TETA4? analogues, and decrease in the case of BP18C62? complexes. The resulting stability trend is the result of a subtle balance between the increased binding energies of the ligand across the lanthanide series, which contribute to an increasing complex stability, and the increase in the absolute values of hydration energies along the 4f period. 相似文献
77.
Inside Cover: Fluoride‐Bridged {GdIII3MIII2} (M=Cr,Fe, Ga) Molecular Magnetic Refrigerants (Angew. Chem. Int. Ed. 9/2014)
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78.
Meiling Chen Chenxi Peng Yaoquan Su Xue Chen Prof. Yuezhou Zhang Prof. Yu Wang Prof. Juanjuan Peng Dr. Qiang Sun Prof. Xiaowang Liu Prof. Wei Huang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21174-21181
The ability to incorporate functional metal ions (Mn+) into metal–organic coordination complexes adds remarkable flexibility in the synthesis of multifunctional organic–inorganic hybrid materials with tailorable electronic, optical, and magnetic properties. We report the cation-exchanged synthesis of a diverse range of hollow Mn+-phytate (PA) micropolyhedra via the use of hollow Co2+-PA polyhedral networks as templates at room temperature. The attributes of the incoming Mn+, namely Lewis acidity and ionic radius, control the exchange of the parent Co2+ ions and the degree of morphological deformation of the resulting hollow micropolyhedra. New functions can be obtained for both completely and partially exchanged products, as supported by the observation of Ln3+ (Ln3+=Tb3+, Eu3+, and Sm3+) luminescence from as-prepared hollow Ln3+-PA micropolyhedra after surface modification with dipicolinic acid as an antenna. Moreover, Fe3+- and Mn2+-PA polyhedral complexes were employed as magnetic contrast agents. 相似文献
79.
Dr. Zhenhua Gao Baoyuan Xu Tongjin Zhang Zhen Liu Weiguang Zhang Xun Sun Yang Liu Dr. Xue Wang Dr. Zifei Wang Prof. Yongli Yan Prof. Fengqin Hu Prof. Xiangeng Meng Prof. Yong Sheng Zhao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(43):19222-19226
Micro/nanoscale photonic barcodes based on multicolor luminescent segmented heterojunctions hold potential for applications in information security. However, such multicolor heterojunctions reported thus far are exclusively based on static luminescent signals, thus restricting their application in advanced confidential information protection. Reported here is a strategy to design responsive photonic barcodes with heterobimetallic (Tb3+/Eu3+) metal—organic framework multicolor heterostructures. The spatial colors could be precisely controlled by thermally manipulating the energy-transfer process between the two lanthanides, thus achieving responsive covert photonic barcodes. Also demonstrated is that spatially resolved responsive barcodes with multi-responsive features could be created in a single heterostructure. These findings offer unique opportunities to purposely design highly integrated responsive microstructures and smart devices toward advanced anti-counterfeiting applications. 相似文献
80.
Vijay S. Parmar Dr. Fabrizio Ortu Dr. Xiaozhou Ma Dr. Nicholas F. Chilton Dr. Rodolphe Clérac Dr. David P. Mills Prof. Dr. Richard E. P. Winpenny 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(35):7774-7778
A new family of five-coordinate lanthanide single-molecule magnets (Ln SMMs) [Dy(Mes*O)2(THF)2X] (Mes*=2,4,6-tri-tert-butylphenyl; X=Cl, 1 ; Br, 2 ; I, 3 ) is reported with energy barriers to magnetic reversal >1200 K. The five-coordinate DyIII ions have distorted square pyramidal geometries, with halide anions on the apex, and two Mes*O ligands mutually trans- to each other, and the two THF molecules forming the second trans- pair. These geometrical features lead to a large magnetic anisotropy in these complexes along the trans-Mes*O direction. QTM and Raman relaxation times are enhanced by varying the apex halide from Cl to Br to I, or by dilution in a diamagnetic yttrium analogue. 相似文献