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排序方式: 共有467条查询结果,搜索用时 15 毫秒
1.
We prove that a finite solvable group G has at least (49p+1)/60 conjugacy classes whenever p is a prime such that p2 divides the order of G. We also construct an infinite family of finite solvable groups, where this bound is attained. 相似文献
2.
Pierre Laszlo 《Angewandte Chemie (International ed. in English)》1978,17(4):254-266
With the availability of Fourier transform spectrometers, 23Na-NMR spectroscopy has become an important tool. It affords direct insight into solvation and ion pairing phenomena, both in organic and in bio-inorganic systems. Monitoring the chemical shifts and linewidths of 23Na signals gives access to binding constants, reorientational correlation times and the microdynamics of the sodium coordination shell. The binding of other cations can also be studied by 23Na-NMR spectroscopy, in competition experiments. 相似文献
3.
Stevens SM Chung AY Chow MC McClung SH Strachan CN Harmon AC Denslow ND Prokai L 《Rapid communications in mass spectrometry : RCM》2005,19(15):2157-2162
A fluorescent affinity tag (FAT) was synthesized and was utilized to selectively modify phosphorylated serine and threonine residues via beta-elimination and Michael addition chemistries in a 'one-step' reaction. This labeling technique was used for covalent modification of both phosphoproteins and phosphopeptides, allowing identification of these molecular species by fluorescence imaging after solution- or gel-based separation methods. In addition to the strong fluorescence of the rhodamine tag, a commercially available antibody can be used to enrich low-abundance post-labeled phosphopeptides present in complex mixtures. Application of this methodology to phosphorylation-site mapping has been evaluated for a phosphoprotein standard, bovine beta-casein. Initial results demonstrated low femtomole detection limits after fluorescence image analysis of FAT-labeled proteins or peptides. 相似文献
4.
Crowe MC Kapoor RN Cervantes-Lee F Párkányí L Schulte L Pannell KH Brodbelt JS 《Inorganic chemistry》2005,44(18):6415-6424
Electrospray ionization (ESI) quadrupole ion trap mass spectrometry (QIT-MS) and collisionally activated dissociation (CAD) were used to evaluate the rare-earth binding properties of two hydrophobic carbamoylmethylphosphine oxide (CMPO) ligands, the normal bidentate variety, (t-BuC6H4)2P(O)CH2C(O)N(i-Bu)2 (A), a new potentially tridentate extractant, (t-BuC6H4)2P(O)CH[CH2C(O)N(i-Bu)2]C(O)N(i-Bu)2 (B), and tributyl phosphate. The mass spectral results obtained from analysis of 1% HNO3/methanol solution containing the ligands and dissolved lanthanide salts reveal that the favorable stoichiometries of the ligand/metal/nitrate complexes are 2:1:2 for the bidentate ligand A, 1:1:2 for the tridentate ligand B, and 3:1:2 for the monodentate tributyl phosphate. These observed stoichiometries correlate with the number of available binding sites on each ligand as well as with potential steric effects. Energy-variable collisionally activated dissociation experiments showed that for the 2:1:2 complexes involving ligand A or B, as the ionic radius of the bound metal decreased, the removal of nitric acid required less energy and resulted in less extensive spontaneous solvent coordination. This experimental trend suggests that, as the ionic radius of the lanthanide ion decreases, a pair of the carbamoylmethylphosphine ligands is able to more completely solvate the bound metal ion thereby weakening the nitrate-metal interaction. 相似文献
5.
Stphane Chalais Andr Cornlis Andr Gerstmans Wacaw Koodziejski Pierre Laszlo Arthur Mathy Pierre Mtra 《Helvetica chimica acta》1985,68(5):1196-1203
Multiple chlorinations and arylations at the tertiary positions of adamantane are promoted by FeCl3-doped K10 montmorillonite in CCl4 or in aromatic solvents. The process, remarkably easy to implement, can be tailored to selective formation of monosubstituted 1-adamantyl derivatives or 1,3-disubstituted adamantanes. The process achieves alkylation at the meta- and para-positions of toluene leading to a purely statistical distribution and displays no substrate specificity in competition experiments between toluene and benzene. 相似文献
6.
Rudolf Janoschek Edwin Hengge Harald Stüger Laszlo Nyulaszi 《Monatshefte für Chemie / Chemical Monthly》1991,122(1-2):31-34
Summary He (I) PE spectra of cyclopentasilane and cyclohexasilane show excellent agreement with STO-3 G + ab initio calculations. The HOMO in both compounds is of (SiSi) 3 p character. First IP's appear at 9.4 and 9.6 eV respectively.
Photoelektronenspektren von Cyclopolysilanen (Kurze Mitt.)
Zusammenfassung Die He (I) PE-Spektren der Cyclosilane Si5H10 und Si6H12 zeigen ausgezeichnete Übereinstimmung mit STO-3 G + ab initio Rechnungen. Beide Ringe besitzen HOMO's mit (SiSi) 3 p Charakter. Die ersten Ionisierungspotentiale liegen bei 9.4 bzw. 9.6 eV.相似文献
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9.
Alinchenko MG Voloshin VP Medvedev NN Mezei M Pártay L Jedlovszky P 《The journal of physical chemistry. B》2005,109(34):16490-16502
The properties of the interatomic voids present in fully hydrated dimyristoylphosphatidylcholine (DMPC)-cholesterol mixed membranes of different compositions are analyzed in detail using a generalized variant of the Voronoi-Delaunay method on the basis of computer simulation results. The systems investigated are chosen from both sides of the DMPC-cholesterol miscibility gap; the pure DMPC bilayer has also been included in the analysis as a reference system. The results obtained show that the empty space is organized in a more compact way, forming larger voids in the presence than in the absence of cholesterol. The voids located in the region of the rigid cholesterol rings become, on average, less spherical, oriented more parallel with the membrane normal axis with increasing cholesterol concentration, whereas an opposite effect of cholesterol is observed in the middle of the membrane among the chain terminal methyl groups. In general, the preferential orientation of the voids is found to strongly correlate with that of the molecules in the hydrocarbon phase of the membranes. The membranes are found to contain rather large voids, the volume of which can be an order of magnitude larger than the largest spherical cavities present in the systems. These voids are elongated or branching channels rather than big empty holes. The voids located among the DMPC and cholesterol molecules are lying preferably parallel with the membrane normal axis. The existence of such empty channels can be of great importance in the cross-membrane permeation of small, uncharged penetrants, in particular, of polar molecules. 相似文献
10.