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101.
Synthesis, Crystal Structure, and Magnetic Properties of TbAl3Cl12 TbAl3Cl12 was synthesized and the crystal structure was determined from single crystal X‐ray diffraction data for the first time. The compound crystallizes trigonally in space group P3112 with a = 1049.8(1) and c = 1567.3(2) pm. Terbium cations are located in quadratic antiprisms of chloride anions. Magnetic measurements were performed to study the interactions between Tb3+ and Cl–. Magnetic data were interpreted by ligand field calculations applying the angular overlap model. 相似文献
102.
Greta R. Patzke Michael Binnewies Ulrich Nigge Hans‐Dieter Wiemhfer 《无机化学与普通化学杂志》2000,626(11):2340-2346
Chemical Transport of Solid Solutions. 8. Transport Phenomena and Ionic Conductivity in the In2O3/SnO2 System Chemical transport reactions are a suitable pathway to the preparation of In2O3‐rich and SnO2‐rich mixed crystals coexisting in the In2O3/SnO2 system (Cl2 as transport agent, 1050 → 900 °C). Experiments are consistent with thermodynamic calculations. The existence of other phases in the system In2O3/SnO2 could not be confirmed. The ionic conductivity of In2O3(SnO2) was investigated. 相似文献
103.
Greta Markert Eno Paenurk Dr. Renana Gershoni-Poranne 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(23):6923-6935
Triplet-state aromaticity has been recently proposed as a strategy for designing functional organic electronic compounds, many of which are polycyclic aromatic systems. However, in many cases, the aromatic nature of the triplet state cannot be easily predicted. Moreover, it is often unclear how specific structural manipulations affect the electronic properties of the excited-state compounds. Herein, the relationship between the structure of polybenzenoid hydrocarbons (PBHs) and their spin-density distribution and aromatic character in the first triplet excited state is studied. Although a direct link is not immediately visible, classifying the PBHs according to their annulation sequence reveals regularities. Based on these, a set of guidelines is defined to qualitatively predict the location of spin and paratropicity and the singlet–triplet energy gap in larger PBHs, using only their smaller tri- and tetracyclic components, and subsequently tested on larger systems. 相似文献
104.
Valeria Amendola Dr. Greta Bergamaschi Dr. Massimo Boiocchi Dr. Luigi Fabbrizzi Prof. Michele Milani Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(14):4368-4380
The interaction of a neutral squaramide‐based receptor, equipped with two 4‐nitrophenyl substituents ( Rsq ), with halides and oxoanions has been studied in MeCN. UV/Vis and 1H NMR spectroscopy titration experiments clearly indicated the formation of 1:1 hydrogen bonding [ Rsq ???X]+ complexes with all the investigated anions. X‐ray diffraction studies on the chloride and bromide complex salts confirmed the 1:1 stoichiometry and indicated the establishment of bifurcated hydrogen‐bond interactions between the squaramide‐based receptor and the halide anion that involved both 1) amide N? H and 2) aryl proximate C? H fragments, for a total of four bonds. Probably due to the contribution of C? H fragments, complexes of Rsq with halides are 1 to 2 orders of magnitude more stable than the corresponding ones with the analogous urea‐based receptor that contains two 4‐nitrophenyl substituents ( Rur ). In the case of oxoanions, Rsq forms complexes, the stability of which decreases with the decreasing basicity of the anion (H2PO4?>NO2?≈HSO4?>NO3?), and is comparable to that of complexes of the urea‐based receptor Rur . Such a behaviour is ascribed to the predominance of different contributions: electrostatic interaction for halides, acid‐to‐base ‘frozen’ proton transfer for oxoanions. Finally, with the strongly basic anions F? and CH3COO?, Rsq first gives genuine hydrogen‐bond complexes of 1:1 stoichiometry; then, upon addition of a second anion equivalent, it undergoes deprotonation of one N? H fragment, with the simultaneous formation of the dianion hydrogen‐bond complexes, [HF2]? and [CH3COOH???CH3COO]?, respectively. In the case of the urea‐based derivative Rur , deprotonation takes place with fluoride but not with acetate. The apparently higher Brønsted acidity of Rsq with respect to Rur reflects the capability of the squaramide receptor to delocalise the negative charge formed on N? H deprotonation over the cyclobutene‐1,2‐dione ring and the entire molecular framework. 相似文献
105.
106.
107.
Nathan A.S. Webster Melissa J. Loan Ian C. Madsen Robert B. Knott Greta M. Brodie Justin A. Kimpton 《Journal of Crystal Growth》2012,340(1):112-117
Lepidocrocite and ferrihydrite-seeded Al(OH)3 crystallisation from supersaturated sodium aluminate liquor at 70 °C was investigated using in situ synchrotron X-ray diffraction. The presence of iron oxides and oxyhydroxides in the Bayer process has implications for the nucleation and growth of scale on process equipment, and a greater understanding of the effect they have on Al(OH)3 crystallisation may allow for development of methods for Al(OH)3 scale prevention. The early stages of both crystallisation reactions were characterised by nucleation of gibbsite on the seed material. This was followed by a rapid increase in gibbsite concentration, which coincided with the appearance of the bayerite and nordstrandite polymorphs of Al(OH)3. The lepidocrocite-seeded reaction then proceeded via a mechanism similar to that which has been observed previously for goethite, hematite and magnetite-seeded Al(OH)3 crystallisation. Different behaviour was observed in the ferrihydrite-seeded experiment, with nucleation as well as growth occurring during the period of rapid increase in gibbsite concentration, followed by a period of diffusion controlled growth. 相似文献
108.
Greta Balan Olga Burduniuc Irina Usataia Vasilii Graur Yurii Chumakov Peter Petrenko Valentin Gudumac Aurelian Gulea Elena Pahontu 《应用有机金属化学》2020,34(3):e5423
New zinc (II), copper (II), nickel (II) and cobalt (III) complexes, [Zn (HL)2]I2 (1) , [Cu (HL)Cl2] (2) , [Cu (HL)Br2] (3) , [Cu (HL)(H2O)2](ClO4)2 (4) , [Ni (HL)2]I2·H2O (5) , [Co(L)2]Cl (6) , [Co(L)2]NO3 (7) , [Co(L)2]I·[Co(L)2](I3) (8) were obtained with 2-formylpyridine 4-allyl-S-methylisothiosemicarbazone ( HL ). The isothiosemicarbazone ligand was characterized by NMR (1H and 13C), IR spectroscopy and X-ray diffraction. All the complexes were characterized by elemental analysis, IR, UV–Vis, ESI-MS spectroscopy, molar conductivity, magnetic susceptibility measurements. X-ray diffraction analysis on the monocrystal and powder elucidated the structure of the complexes 1 , 5 , 7 and 8 . The ligand and the complexes were tested for their antioxidant and antimicrobial activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Candida albicans. Also, the antiproliferative properties of these compounds on human leukemia HL-60, human cervical epithelial HeLa, human epithelial pancreatic adenocarcinoma BxPC-3, human muscle rhabdomyosarcoma spindle, large multinucleated RD cells and normal MDCK cells have been investigated. The nickel complex 5 and cobalt complexes 6 , 7 showed promising antiproliferative activity and low toxicity. 相似文献
109.
110.
Eva Valtcheva Stefka Veleva Greta Radeva Ivo Valtchev 《Reaction Kinetics and Catalysis Letters》2003,78(1):183-191
The present work aims a systematic kinetic investigation of the delignification action of the laccase-mediator system in the
presence of oxygen. A dimensionless quantity a representing the degree of delignification was used as a criterion for the enzyme efficiency. It was found that the exponential
equation which describes the kinetics of processes taking place on a uniformly inhomogeneous surface, fits the experimental
results with the highest degree of statistical confidence. The activation energy Eobtained is independent of the delignification degree a, while the pre-exponential factor A decreases in the course of the process. It is mostly connected to the spatial limitations, the exhaustion of phenolic subunits
available as well as to the decrease of the indirect activity of the non-phenolic structure in the lignin.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献