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51.
52.
P. Ehrenberg C. Diebel und H. Veckenstedt 《Fresenius' Journal of Analytical Chemistry》1913,52(7-8):408-418
Ohne Zusammenfassung(Aus dem agrikulturchemischen Institut der Universität Göttingen.) 相似文献
53.
54.
Ohne Zusammenfassung 相似文献
55.
D B?ckstr?m M Ingelman-Sundberg A Ehrenberg 《Acta chemica Scandinavica. Series B: Organic chemistry and biochemistry》1983,37(10):891-894
The redox midpoint potentials of rabbit liver microsomal cytochromes P-450 and of soluble and membrane-bound rabbit liver microsomal cytochrome P-450 LM2 were determined using EPR-spectroscopy and absorption difference spectrometry with NADPH or dithionite as reductants. Using EPR, a redox midpoint potential of -0.36 V was obtained both for the low spin and the high spin components of microsomal cytochrome P-450. Spectrophotometrical determinations yielded very similar values: -0.37 V and -0.34 V for the low and high spin signals, respectively. Soluble cytochrome P-450 LM2 had a midpoint potential of -0.32 V. This redox potential was not significantly affected by incorporation of the protein into an artificial membrane structure or, furthermore, by the presence of cytochrome b5 the same membrane. 相似文献
56.
Consumers' expressed Intentions-to-buy different brands are frequently measured in marketing research. Study of several hundred surveys shows that a relationship between the percentage I of consumers expressing such an Intention-to-buy and the percentage U claiming current Usage of the brand can be represented by a single one-parameter relationship I = K √U ± 3. This holds for different brands (large and small) in over 20 product-fields, for different demographic subgroups, for certain different definitions of the Intentions and Usage variables, for some American as well as British data, and even for trends over time.Both the nature of this relationship between I and U and the paradoxical finding that relatively few people express an Intention-to-buy a new brand which is sub-sequently successful and that relatively many people do so for a brand which is slowly dying are explained by the effect of past Usage. Methodological conclusions of the findings are indicated. 相似文献
57.
Balevicius V Bariseviciute R Aidas K Svoboda I Ehrenberg H Fuess H 《Physical chemistry chemical physics : PCCP》2007,9(24):3181-3189
In this work the role of higher molecular aggregation in the proton transfer processes within hydrogen bond (H-bond) is investigated. The H-bonded complex consisting of 4-cyanopyridine (CyPy) with trichloroacetic acid (TCA) has been studied in the solutions of acetonitrile, carbon tetrachloride, chloroform and dichloroethane as solvent by FTIR spectroscopy and quantum chemical DFT calculations. In order to illustrate the effect of increasing H-bond strength FTIR investigations have also been performed on solutions of CyPy with H(2)O, acetic-, trifluoroacetic- and methanesulfonic acids. Proton states in the H-bond have been monitored using vibrational CyPy ring modes in FTIR spectra. The stabilization of the CyPy/TCA complex in its protonated form upon increasing polarity of the solvent has been evidenced. It was shown that formation of the CyPy/(TCA)(2) aggregates in the solutions favors the proton transfer process. An X-ray diffraction study has been performed on a single 1 : 2 co-crystal of pyridine/3,5-dinitrobenzoic acid. The H-bond motif found in this system exhibits the same connectivity by strong hydrogen bonds N-H(+)[dot dot dot]O(-) and O-H[dot dot dot]O as that in the CyPy/(TCA)(2) complex predicted by DFT calculation. Certain discrepancies are observed in C-H[dot dot dot]O connectivity only. The networks of H-bonds in both assemblies differ from those usually pictured for 1 : 2 base/carboxylic acid complexes in the literature. 相似文献
58.
The acid-base, spectroscopic, photophysical and liposome-binding properties of the recently synthesized free base, 29H,31H,1,4,8,11,15,18,22,25-octafluoro-2,3,9,10,16,17,23, 24-octakisperfluoro(isopropyl) phthalocyanine, F64PcH2, are reported. The perfluoroalkylation of the phthalocyanine core renders the hydrogen atoms acidic, with a pK(a) = 6. The F64Pc(-2) dianion is detected already at pH 3, by singular-value decomposition analysis of electronic spectra. F64Pc(-2) generates 1O2 with quantum yields phi(delta) = 0.252 (in MeOH) and 0.019 in liposomes. Metallation of the Pc macrocycle to yield F64PcZn increases phi(delta) to 0.606 and 0.126 in MeOH and liposomes, respectively. Surprisingly, F64Pc(-2) (but not F64PcH2 or F64PcZn) binds strongly to liposomes, with a binding constant K(b) = 25 (mg/mL)(-1). The fully protonated F64PcH2, but not the zwitterionic F64Pc(-2), might favor hydrogen bonding, thus reducing its lipophilicity. Similarly, the Lewis acidity of Zn in F64PcZn, and thus its ability to bind water within a hydrophobic perfluoroalkyl pocket, is significantly enhanced by the fluorinated substituents. 相似文献
59.
Ahmed M. Hashem Ashraf E. Abdel Ghany Kristian Nikolowski Helmut Ehrenberg 《Ionics》2010,16(4):305-310
LiNi0.5Mn0.5O2 powder was synthesized by a coprecipitation method. LiOH.H2O and coprecipitated [(Ni0.5Mn0.5)C2O4] precursors were mixed carefully together and then calcined at 900°C. Surface modified cathode materials were obtained by
coating LiNi0.5Mn0.5O2 with a thin layer of amorphous carbon using table sugar and starch as carbon source. Both parent and carbon-coated samples
have the characteristic layered structure of LiNi0.5Mn0.5O2 as estimated from X-ray diffractometry measurements. Transmission electron microscope showed the presence of C layer around
the prepared particles. TGA analysis emphasized and confirmed the presence of C coating around LiNi0.5Mn0.5O2. It is obvious that the carbon coating appears to be beneficial for the electrochemical performance of the LiNi0.5Mn0.5O2. A capacity of about 150 mAh/g is delivered in the voltage range 2.5–4.5 V at current density C/15 for carbon coated LiNi0.5Mn0.5O2 in comparison with about 165 mAh/g obtained for carbon free LiNi0.5Mn0.5O2 at the same current density and voltage window. About 92% and 82% capacity retention was obtained at 50th cycle for coated
LiNi0.5Mn0.5O2 using sucrose and starch, respectively; whereas, 75% was retained after only 30th cycle for carbon free LiNi0.5Mn0.5O2. This improvement is mainly attributed to the presence of thin layer of carbon layer that encapsulate the nanoparticles and
improve the conductivity and the electrochemical performance of LiNi0.5Mn0.5O2. 相似文献
60.
Ye Yao Lu Zhang Florian Sigel Bj?rn Schwarz Helmut Ehrenberg Gang Chen Fei Du Chunzhong Wang 《Journal of Energy Chemistry》2021,(9):222-228
The approach of substituting electrochemically active with inactive elements has widely been used to improve the electrochemical performance of Li-rich intercal... 相似文献