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101.
Chaurand P Rose J Briois V Salome M Proux O Nassif V Olivi L Susini J Hazemann JL Bottero JY 《The journal of physical chemistry. B》2007,111(19):5101-5110
This paper presents a comparison between several methods dedicated to the interpretation of V K-edge X-ray absorption near-edge structure (XANES) features. V K-edge XANES spectra of several V-bearing standard compounds were measured in an effort to evaluate advantages and limits of each method. The standard compounds include natural minerals and synthetic compounds containing vanadium at various oxidation state (from +3 to +5) and in different symmetry (octahedral, tetrahedral, and square pyramidal). Correlations between normalized pre-edge peak area and its centroid position have been identified as the most reliable method for determining quantitative and accurate redox and symmetry information for vanadium. This methodology has been previously developed for the Fe K edge. It is also well adapted for the V K edge and is less influenced by the standard choice than other methods. This methodology was applied on an "environmental sample," i.e., a well-crystallized leached steel slag containing vanadium as traces. Micro-XANES measurements allowed elucidating the microdistribution of vanadium speciation in leached steel slag. The vanadium exhibits an important evolution from the unaltered to the altered phases. Its oxidation state increases from +3 to +5 together with the decrease of its symmetry (from octahedral to tetrahedral). 相似文献
102.
Jacques Gilloteaux James M Jamison David Arnold Henryk S Taper Vivian E Von Gruenigen Jack L Summers 《Microscopy and microanalysis》2003,9(4):311-329
Human ovarian carcinoma cells (MDAH 2774) were treated with sodium ascorbate (VC), menadione (VK3), or with a VC:VK3 combination for 1 h and then studied using light microscopy (LM) and scanning (SEM) and transmission electron (TEM) microscopy. Plasma membrane damage (blisters and blebs, hairy aspect) results from vitamin C (VC) treatment, while cytoskeletal damage and self-morsellation are caused by vitamin K3 (VK3) treatment. VC:VK3-treated cells exhibit exacerbated injuries characteristic of both VC and VK3 treatment as well as a significant decrease in cell diameters from 20-35 microm for control cells to 7-12 microm for VC:VK3 treatment. Moreover, after a 1-h exposure to the vitamin combination, autoschizis (43%), apoptosis (3%), and oncosis (1.9%) are observed at the percentages indicated. All cellular changes associated with autoschizis observed with SEM were confirmed by LM and TEM observations and are consistent with cell death by autoschizis: decrease in cell size, cytoplasmic self-excisions, degradation of the nucleus and nucleolus without formation of apoptotic bodies and, ultimately, karyorrhexis and karyolysis. These results also suggest that the vitamin combination may find clinical use in the treatment of ovarian cancer. 相似文献
103.
Jeroen van Westrenen A. Dean Sherry Won Dae Kim Anne E. Vivian Duane C. Hrncir 《Journal of chemical crystallography》1993,23(11):885-890
C5H10N2O3S,1, monoclinicC2/c,a=17.545(5),b=6.822(8),c=13.928(2),=108.36(7),Z=8, MoK, =0.7107 Å,=3.56cm–1,R=0.061,R
w
=0.099. C8H16N3O6S2Na·2H2O,2, orthorhombicPna21,a=17.964(8),b=10.157(1),c=8.263(4),Z=4, MoK, =0.7107 Å,=4.07 cm–1,R=0.040,R
w
=0.043. C10H20N4O6S2·2H2O,3, monoclinicP21/n,a=9.142(9),b=13.576(7),c=14.028(8),=94.096(8),Z=4, MoK, =0.7107 Å,=3.37 cm–1,R=0.063,R
w
=0.074. Compounds1, 2, and3 were prepared from the pH-dependent sulfomethylation of the di- and polyazamacrocycles. 相似文献
104.
105.
106.
Shuai Liu Yujie Wu Teng Lin Robert Abel Jonathan P. Redmann Christopher M. Summa Vivian R. Jaber Nathan M. Lim David L. Mobley 《Journal of computer-aided molecular design》2013,27(9):755-770
Alchemical free energy calculations hold increasing promise as an aid to drug discovery efforts. However, applications of these techniques in discovery projects have been relatively few, partly because of the difficulty of planning and setting up calculations. Here, we introduce lead optimization mapper, LOMAP, an automated algorithm to plan efficient relative free energy calculations between potential ligands within a substantial library of perhaps hundreds of compounds. In this approach, ligands are first grouped by structural similarity primarily based on the size of a (loosely defined) maximal common substructure, and then calculations are planned within and between sets of structurally related compounds. An emphasis is placed on ensuring that relative free energies can be obtained between any pair of compounds without combining the results of too many different relative free energy calculations (to avoid accumulation of error) and by providing some redundancy to allow for the possibility of error and consistency checking and provide some insight into when results can be expected to be unreliable. The algorithm is discussed in detail and a Python implementation, based on both Schrödinger’s and OpenEye’s APIs, has been made available freely under the BSD license. 相似文献
107.
108.
Vivian De Smedt 《Letters in Mathematical Physics》1994,30(2):105-117
We give the decomposition into irreducible components of the curvature tensor of a hyper-Kähler manifold. 相似文献
109.
Daptomycin (Cubicin) is a lipopeptide antibiotic approved in the USA in 2003 for the treatment of skin and skin structure infections caused by Gram-positive pathogens. It is a member of the 10-membered cyclic lipopeptide family of antibiotics that includes A54145, calcium-dependent antibiotic (CDA), amphomycin, friulimicin, laspartomycin, and others. This review highlights research on this class of antibiotics from 1953 to 2005, focusing on more recent studies with particular emphasis on the interplay between structural features and antibacterial activities; chemical modifications to improve activity; the genetic organization and biosynthesis of lipopeptides; and the genetic engineering of the daptomycin biosynthetic pathway to produce novel derivatives for further chemical modification to develop candidates for clinical evaluation. 相似文献
110.
Yu SY Zhang ZX Cheng EC Li YZ Yam VW Huang HP Zhang R 《Journal of the American Chemical Society》2005,127(51):17994-17995
A luminescent supramolecular chiral Au16 ring with 4.822 nm perimeter that self-assembled from a tetrameric array of achiral Au2 units is described. Intra- and intermolecular Au...Au interactions play an important role in directing its chiral self-assembly. 相似文献