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91.
Antje Klockow H. Michael Widmer Renato Amado Aran Paulus 《Fresenius' Journal of Analytical Chemistry》1994,350(7-9):415-425
The detection limits of the ANTS (8-aminonaphthalene-1,3,6-trisulfonic acid) label and ANTS maltose as a model carbohydrate conjugate were investigated with on-column UV and laser induced fluorescence detection. Under capillary electrophoresis conditions, the concentration and mass detection limits were found to be 5×10–7 mol/l or 8 femtomole with UV and 5×10–8 mol/l or 400 attomole with laser induced fluorescence detection, respectively. Including the derivatization reaction, the best concentration detection limit increases to 1×10–6 mol/l carbohydrate. A model calculation shows that these detection levels are still insufficient to match those of current protein sequencing protocols.Derivatization conditions for dextran and polygalacturonic acid ladders are described with subsequent fast separation in a capillary electrophoresis system under acidic pH buffer conditions. Up to 30 oligomers could be separated in less than 10 min. The application of ANTS labelled carbohydrate analysis in the food industry is demonstrated with the carbohydrate fraction of sweets and the kinetic monitoring of the hydrolysis of polygalacturonic acid.The described ANTS derivitization protocol works with as little as 5 g carbohydrate as demonstrated with a complex oligosaccharide labelled in a reaction volume as little as 2 l. To demonstrate the applicability of this approach to complex carbohydrate analysis, an oligosaccharide mixture derived from human Immunoglobuline G was labelled and separated within 5 min. Separation efficiency and speed are superior to state-of-the-art chromatographic methods. Both electrophoretic and chromatographic methods are complementary because of their different separation mechanism. The implications of using capillary electrophoresis with laser induced fluorescence and appropriate labelling strategies for structural and compositional analysis of complex carbohydrates are discussed.Dedicated to Professor Dr. Dieter Klockow on the occasion of his 60th birthday 相似文献
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Polyacrylamide-filled gel columns are used to separate oligonucleotide samples. For homopolymeric standard samples, plots of migration time versus molecular size are presented over a range of 30-160 bases. With 2.5-4% T and 3.3% C gels, good resolution over the examined mass range, with peak width at half height of 3 to 6 s, is obtained by applying electrical fields of 200-400 V/cm. The separation of heteropolymeric nucleotides by slab gel electrophoresis under routine conditions was compared with capillary gel electrophoresis. Using the same column and the same separation conditions, the plot of migration time versus base number is linear with an identical slope for three oligonucleotide samples which were examined, allowing a calibration of a gel-filled capillary for molecular mass determination. 相似文献
94.
Shivanyuk A Paulus EF Rissanen K Kolehmainen E Böhmer V 《Chemistry (Weinheim an der Bergstrasse, Germany)》2001,7(9):1944-1951
Crystal structures are reported for various co-crystals of rccc-resorcarenes with triethylammonium chloride. Usually, two molecules of a C2v-symmetric tetraester 2 in the boat conformation are linked through four hydrogen-bonded chloride anions to give dimeric assemblies. Two of the chloride anions may be replaced by four hydrogen-bonded ethanol molecules in an otherwise similar structure. These assemblies, which consist of six or eight components, posses voluminous, negatively charged chambers in which two triethylammionium cations, 3+, are included as guests by strong electrostatic and hydrogen-bonding interactions. The host-guest N-H...Cl hydrogen bonds were clearly detected at 173 K. These are the first examples of hydrogen-bonded, solid-state capsules trapping two ions of the same charge in close proximity. In the 1:2 complex with 3+ Cl-, the molecule of the parent resorcarene 1 also adopts a boat conformation whose cavity is considerably extended by four hydrogen-bonded chloride anions. The pocket formed in this way again includes two 3+ ions as a result of electrostatic and hydrogen bonding host-guest interactions. All these structures show that the boat conformers of resorcarenes can be used as a novel motif for the construction of hydrogen-bonded assemblies capable of molecular inclusion and encapsulation. 相似文献
95.
In the course of screening new streptomycete strains, the strain Streptomyces sp. Cl 58-27 caught our attention due to its interesting secondary metabolite production profile. Here, we report the isolation and characterization of an ansamycin natural product that belongs structurally to the already known kendomycins. The structure of the new kendomycin E was elucidated using NMR spectroscopy, and the corresponding biosynthetic gene cluster was identified by sequencing the genome of Streptomyces sp. Cl 58-27 and conducting a detailed analysis of secondary metabolism gene clusters using bioinformatic tools. 相似文献
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Peptide natural products displaying a wide range of biological activities have become important drug candidates over the years. Microorganisms have been a powerful source of such bioactive peptides, and Streptomyces have yielded many novel natural products thus far. In an effort to uncover such new, meaningful compounds, the metabolome of Streptomyces acidiscabies was analyzed thoroughly. Three new compounds, scabimycins A–C (1–3), were discovered, and their chemical structures were elucidated by NMR spectroscopy. The relative and absolute configurations were determined using ROESY NMR experiments and advanced Marfey’s method. 相似文献
100.
R. Klement F. Stock H. Elias H. Paulus P. Pelikn M. Valko M. Mazúr 《Polyhedron》1999,18(27):1356-3628
Salen type complexes, CuL, the corresponding tetrahydrosalen type complexes, Cu[H4]L, and N,N′-dimethylated tetrahydrosalen type complexes, Cu[H2Me2]L, were investigated using cyclic voltammetry, and electronic and ESR spectroscopy. In addition, the analogous copper(II) complexes with a derivative of the tetradentate ligand ‘salphen’ [salphen=H2salphen=N,N′-disalicylidene-1,2-diaminobenzene] were studied. Solutions of CuL, Cu[H4]L and Cu[H2Me2]L are air-stable at ambient temperature, except for the complex Cu(tBu, Me)[H4]salphen [H2(tBu, Me)[H4]salphen=N,N′-bis(2-hydroxy-3-tert-butyl-5-methylbenzyl)-1,2-diaminobenzene]. Cu(tBu, Me)[H4]salphen interacts with dioxygen and the ligand is oxidatively dehydrogenated (–CH2–NH–→–C=N–) to form Cu(tBu, Me)[H2]salphen and finally, in the presence of base, Cu(tBu, Me)salphen. X-ray structure analysis of Cu(tBu, Me)[H2Me2]salen confirms a slightly tetrahedrally distorted planar geometry of the CuN2O2 coordination core. The complexes were subjected to spectrophotometric titration with pyridine, to determine the equilibrium constants for adduct formation. It was found that the metal center in the complexes studied is only of weak Lewis acidity. In dichlormethane, the oxidation Cu(II)/Cu(III) is quasireversible for the CuL type complexes, but irreversible for the Cu[H4]L and Cu[H2Me2]L type. A poorly defined wave was observed for the irreversible reduction Cu(II)/Cu(I) at potentials less than −1.0 V. The ESR spectra of CuL at both 77 K and room temperature reveal that very well resolved lines can be attributed to the interaction of an unpaired electron spin with the copper nuclear spin, 14N donor nuclei and to a distant interaction with two equivalent protons [ACu(iso)≈253 MHz, AN(iso)≈43 MHz, AN(iso)≈20 MHz]. These protons are attached to the carbon atoms adjacent to the 14N nuclei. In contrast to CuL, the number of lines in the spectra of the complexes Cu[H4]L and Cu[H2Me2]L is greatly reduced. At room temperature, only a quintet with a considerably smaller nitrogen shf splitting constant [AN(iso)≈27 MHz] is observed. Both factors, planarity and conjugation, are thus essential for the observation of distant hydrogen shf splitting in CuL. Due to the C=N bond hydrogenation, the coordination polyhedra of the complexes Cu[H4]L and Cu[H2Me2]L is more flexible and more sensitive to ligand modification than that of CuL. The electron-withdrawing effect of the phenyl ring of the phenylenediamine bridge is reflected in a reduction of the copper hyperfine coupling constants in Cu(tBu, Me)[H4]salphen and Cu(tBu, Me)[H2Me2]salphen complexes [ACu(iso)≈215 MHz]. 相似文献