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371.
Two solid complexes, fac–[Cr(gly)3] and [Cr(gly)2(OH)]2, (where gly is glycinato ligand) were prepared and their acid-catalysed aquation products were identified. The structure
of [Cr(gly)3] was solved by X-ray diffraction, revealing a cationic 3D sublattice with perchlorate anions inside its cavities. Acid-catalysed
aquation of [Cr(gly)3] and [Cr(gly)2(OH)]2 leads to the same inert product, [Cr(gly)2(H2O)2]+, in a two-stages process. At the first stage, intermediate complexes, [Cr(gly)2(O–glyH)(H2O)]+ and [Cr(gly)2(H2O)–OH–Cr(gly)2(H2O)]+, are formed respectively. Kinetics of the first aquation stage of [Cr(gly)3] were studied in HClO4 solutions. The dependencies of the pseudo first-order rate constants on [H+] are as follows: k
obs1H = k
0 + k
1
K
p1[H+], where k
0 and k
1 are rate constants for the chelate-ring opening via spontaneous and acid-catalysed reaction paths, respectively, and K
p1 is the protonation constant. The proposed mechanism assumes formation of the reactive intermediate as a result of proton
addition to the coordinated carboxylate group of the didentate ligand. Some kinetic studies on the second reaction stage,
the one-end bonded glycine liberation, were also done. The obtained results were analogous to those for stage I. In this case,
the proposed reactive species are intermediates, protonated at the carboxylate group of the monodentate glycine. Base hydrolysis
of two complexes, [Cr(gly)2(O–gly)(OH)]− and [Cr(gly)2(OH)2]−, was studied in 0.2–1.0 M NaOH. The pseudo first-order rate constants, k
obsOH, were [OH−] independent in the case of [Cr(gly)2(O–gly)(OH)]−, whereas those for [Cr(gly)2(OH)2]− linearly depended on [OH−]. The reaction mechanisms were proposed, where the OH− -catalysed reaction path was rationalized in terms of formation of the reactive conjugate base, [Cr(gly)2(OH)(O)]2−, as a result of OH− ligand deprotonation. Activation parameters were determined and discussed. 相似文献
372.
Dynamic libraries of [n × n] imine components spontaneously simplify during a slow oxidation reaction to produce only n discrete products. The selectivity of this self-sorting process is a consequence of different oxidation rates for various imines, while the dynamic nature of the library enables self-sorting to proceed with high efficiency. 相似文献
373.
Karolina Sieradzka Danuta Kaczmarek Jarosław Domaradzki Eugeniusz Prociów Michał Mazur Barbara Górnicka 《Central European Journal of Physics》2011,9(2):313-318
Electrical and optical properties of TiO2:Pd thin films deposited from Ti-Pd mosaic targets sputtered in reactive oxygen plasma have been studied. The properties were
investigated for thin films with the Pd amount of 5.5 at. %, 8.4 at. % and 23 at. %. Based on resistivity measurements a drop
from 103 down to almost 10−3Ωcm has been recorded when the Pd amount was varied from 5.5 at. % to 23 at. %, respectively. Moreover, it was shown that
doping with different amounts of Pd results in the possibility of obtaining both types of electrical conduction: n-type for
the TiO2 with 5.5 at. % and 8.4 at. % of Pd and p-type for the TiO2 with 23 at. % of Pd thin films. From optical measurements it has been found that as the Pd amount was increased the transmission
through the thin films was reduced and position of the fundamental absorption edge was shifted toward a longer wavelength
range of up to 600 nm. The optical band gap was calculated for direct and indirect transitions from optical absorption spectra.
Structural properties were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). The XRD patterns displayed
occurrence of the crystalline, TiO2-rutile for lower Pd amounts (5.5 at. %, 8.4 at. %), while the TiO2:Pd (23 at. %) thin films displayed XRD-amorphous behaviour. Images obtained from AFM displayed dense, nanocrystalline structure
with homogenous distribution of crystallites. Additionally performed secondary ion mass spectroscopy investigation confirmed
homogenous distribution of Pd in the whole thickness of the prepared thin films. 相似文献
374.
Janusz W. Strzelecki Joanna Strzelecka Karolina Mikulska Mariusz Tszydel Aleksander Balter Wiesław Nowak 《Central European Journal of Physics》2011,9(2):482-491
Caddisfly (Trichopera) can glue diverse material underwater with a silk fiber. This makes it a particularly interesting subject
for biomimetcs. Better understanding of silk composition and structure could lead to an adhesive capable to close bleeding
wounds or to new biomaterials. However, while spiderweb or silkworm secretion is well researched, caddisfly silk is still
poorly understood. Here we report a first nanomechanical analysis of H. Angustipennis caddisfly silk fiber. An Atomic Force
Microscope (AFM) imaging shows dense 150 nm bumps on silk surface, which can be identified as one of features responsible
for its outstanding adhesive properties. AFM force spectroscopy at the fiber surface showed, among others, characteristic
saw like pattern. This pattern is attributed to sacrificial bond stretching and enhances energy dissipation in mechanical
deformation. Similarities of some force curves observed on Tegenaria domestica spiderweb and caddisfly silk are also discussed.
Steered Molecular Dynamics simulations revealed that the strength of short components of Fib-H HA species molecules, abundant
in Trichoptera silk is critically dependent on calcium presence. 相似文献
375.
Karolina D?ugopolska Joanna Kisa?a Marek Danilczuk Dariusz Pogocki Tomasz Ruman 《Applied magnetic resonance》2010,38(3):321-335
In this paper, we present the detailed study on the correlation of the nuclear magnetic resonance (NMR) parameters with the results of density functional theory calculations performed for paramagnetic high-spin cobalt(II) complexes with trispyrazolylborate ligands. This work focuses on estimation of dipolar and contact shifts in mono-ligand high-spin cobalt(II) pyrazolylborate systems along with discussion on 1H NMR properties of the mentioned tetra-, penta- and hexacoordinate complexes. The calculation results show frontier molecular orbitals that may be responsible for contact shift. The calculated contact shift values are compared with the dipolar shift and hyperfine ones. 相似文献
376.
Proteinuria is a condition in which an excessive amount of protein is excreted in urine. It is, among others, an indicator of kidney disease or risk of cardiovascular disease. Rapid and reliable diagnosis and monitoring of proteinuria is of great importance for both patients and their physicians. For that reason, a paper-based sensor for proteinuria diagnosis was designed, optimized, and validated utilizing smartphone-assisted signal acquisition. In the first step, a few commonly employed protein assays were optimized and compared in terms of analytical performance on paper matrix. The tetrabromophenol blue method was selected as the one providing a sufficiently low limit of detection (39 mg·L−1) on the one hand and appropriate long-term stability (up to 3 months) on the other hand. The optimized assay was employed for protein-to-creatinine ratio (PCR) determination on a single paper-based sensor. For both analytes the linear ranges were within the clinically relevant range. The analytical usefulness of the developed sensors was demonstrated by a PCR recovery study in artificial urine. The obtained PCR recoveries were from ca. 80 to 150%. 相似文献
377.
Krzysztof Lyczko Monika Lyczko Marzena Banasiewicz Karolina Wegrzynska Anna Ziko Anna Baraniak Jan Cz. Dobrowolski 《Molecules (Basel, Switzerland)》2022,27(1)
Synthesis, single-crystal X-ray determination diffraction and FT-IR, NMR (1H, 13C, 19F and 205Tl), UV–vis, and luminescence spectra characteristics were described for series of thallium(I) compounds: thallium(I) triflate (Tl(OTf)), 1:1 co-crystals of thallium(I) triflate and tropolone (Htrop), Tl(OTf)·Htrop, as well as simple thallium(I) chelates: Tl(trop) (1), Tl(5-metrop) (2), Tl(hino) (3), with Htrop, 5-methyltropolone (5-meHtrop), 4-isopropyltropolone (hinokitiol, Hhino), respectively, and additionally more complex {Tl@[Tl(hino)]6}(OTf) (4) compound. Comparison of their antimicrobial activity with selected lead(II) and bismuth(III) analogs and free ligands showed that only bismuth(III) complexes demonstrated significant antimicrobial activity, from two- to fivefold larger than the free ligands. 相似文献
378.
Karolina Woziwodzka Jolanta Mayszko Ewa Koc-rawska Marcin rawski Paulina Dumnicka Artur Jurczyszyn Krzysztof Batko Paulina Mazur Magorzata Banaszkiewicz Marcin Krzanowski Paulina Goasa Jacek A. Mayszko Ryszard Drod Katarzyna Krzanowska 《Molecules (Basel, Switzerland)》2022,27(1)
Transgelin is a 22-kDa protein involved in cytoskeletal organization and expressed in smooth muscle tissue. According to animal studies, it is a potential mediator of kidney injury and fibrosis, and moreover, its role in tumorigenesis is emerging in a variety of cancers. The study included 126 ambulatory patients with multiple myeloma (MM). Serum transgelin-2 concentrations were measured by enzyme-linked immunoassay. We evaluated associations between baseline transgelin and kidney function (serum creatinine, estimated glomerular filtration rate—eGFR, urinary markers of tubular injury: cystatin-C, neutrophil gelatinase associated lipocalin—NGAL monomer, cell cycle arrest biomarkers IGFBP-7 and TIMP-2) and markers of MM burden. Baseline serum transgelin was also evaluated as a predictor of kidney function after a follow-up of 27 months from the start of the study. Significant correlations were detected between serum transgelin-2 and serum creatinine (R = 0.29; p = 0.001) and eGFR (R = −0.25; p = 0.007). Transgelin significantly correlated with serum free light chains lambda (R = 0.18; p = 0.047) and serum periostin (R = −0.22; p = 0.013), after exclusion of smoldering MM patients. Patients with decreasing eGFR had higher transgelin levels (median 106.6 versus 83.9 ng/mL), although the difference was marginally significant (p = 0.05). However, baseline transgelin positively correlated with serum creatinine after the follow-up period (R = 0.37; p < 0.001) and negatively correlated with eGFR after the follow-up period (R = −0.33; p < 0.001). Moreover, higher baseline serum transgelin (beta = −0.11 ± 0.05; p = 0.032) significantly predicted lower eGFR values after the follow-up period, irrespective of baseline eGFR and follow-up duration. Our study shows for the first time that elevated serum transgelin is negatively associated with glomerular filtration in MM and predicts a decline in renal function over long-term follow-up. 相似文献
379.
Karolina Zawadziska Mar Ríos-Gutirrez Karolina Kula Przemysaw Woliski Barbara Mirosaw Tomasz Krawczyk Radomir Jasiski 《Molecules (Basel, Switzerland)》2021,26(22)
The regioselective zw-type [3 + 2] cycloaddition (32CA) reactions of a series of aryl-substituted nitrile N-oxides (NOs) with trichloronitropropene (TNP) have been both experimentally and theoretically studied within the Molecular Electron Density Theory (MEDT). Zwitterionic NOs behave as moderate nucleophiles while TNP acts as a very strong electrophile in these polar 32CA reactions of forward electron density flux, which present moderate activation Gibbs free energies of 22.8–25.6 kcal·mol−1 and an exergonic character of 28.4 kcal·mol−1 that makes them irreversible and kinetically controlled. The most favorable reaction is that involving the most nucleophilic MeO-substituted NO. Despite Parr functions correctly predicting the experimental regioselectivity with the most favorable O-CCCl3 interaction, these reactions follow a two-stage one-step mechanism in which formation of the O-C(CCl3) bond takes place once the C-C(NO2) bond is already formed. The present MEDT concludes that the reactivity differences in the series of NOs come from their different nucleophilic activation and polar character of the reactions, rather than any mechanistic feature. 相似文献
380.