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311.
Bluma G. Soares Gabriel S. Amorim Marcia G. Oliveira J.E. Pereira da Silva 《Macromolecular Symposia》2006,233(1):95-101
Electrically conductive elastomer blends based on polyaniline-dodecylbenzene sulfonic acid (Pani.DBSA) and nitrile rubber (NBR) were prepared by polymerization of aniline in the presence of NBR, using a direct, one-step in situ emulsion polymerization method. At the same PAni content, the conductivity of the in situ emulsion-polymerized blends is higher than that of blends produced by mechanical mixing of both components. In addition, a morphology with the presence of PAni in the form of microtubules was achieved by the in situ process. Stronger interaction between the components were also confirmed by Rheological processing analysis (RPA). The vulcanization process decreases the conductivity of the blends prepared by both methods. The in situ polymerized blends also display higher tensile strength and also higher crosslink density 相似文献
312.
Pedro Novais Patrícia M. A. Silva Joana Moreira Andreia Palmeira Isabel Amorim Madalena Pinto Honorina Cidade Hassan Bousbaa 《Molecules (Basel, Switzerland)》2021,26(23)
Previously, we reported the in vitro growth inhibitory effect of diarylpentanoid BP-M345 on human cancer cells. Nevertheless, at that time, the cellular mechanism through which BP-M345 exerts its growth inhibitory effect remained to be explored. In the present work, we report its mechanism of action on cancer cells. The compound exhibits a potent tumor growth inhibitory activity with high selectivity index. Mechanistically, it induces perturbation of the spindles through microtubule instability. As a consequence, treated cells exhibit irreversible defects in chromosome congression during mitosis, which induce a prolonged spindle assembly checkpoint-dependent mitotic arrest, followed by massive apoptosis, as revealed by live cell imaging. Collectively, the results indicate that the diarylpentanoid BP-M345 exerts its antiproliferative activity by inhibiting mitosis through microtubule perturbation and causing cancer cell death, thereby highlighting its potential as antitumor agent. 相似文献
313.
de Matos Vitor L. Sierra Mauro A. G. Finardi Erlon C. Decker Brigida U. Milanezi André A. S. 《Computational Management Science》2015,12(1):111-127
Computational Management Science - This paper presents a stochastic model for energy commercialisation strategies of small hydro plants (SHPs) in the Brazilian electricity market. The model aims to... 相似文献
314.
Cui X Carapuça HM Delgado R Drew MG Felix V 《Dalton transactions (Cambridge, England : 2003)》2004,(11):1743-1751
The compound bis[1,1'-N,N'-(2-picolyl)aminomethyl]ferrocene, L(1), was synthesized. The protonation constants of this ligand and the stability constants of its complexes with Ni(2+), Cu(2+), Zn(2+), Cd(2+) and Pb(2+) were determined in aqueous solution by potentiometric methods at 25 degrees C and at ionic strength 0.10 mol dm(-3) in KNO(3). The compound L(1) forms only 1:1 (M:L) complexes with Pb(2+) and Cd(2+) while with Ni(2+) and Cu(2+) species of 2 [ratio] 1 ratio were also found. The complexing behaviour of L(1) is regulated by the constraint imposed by the ferrocene in its backbone, leading to lower values of stability constants for complexes of the divalent first row transition metals when compared with related ligands. However, the differences in stability are smaller for the larger metal ions. The structure of the copper complex with L(1) was determined by single-crystal X-ray diffraction and shows that a species of 2:2 ratio is formed. The two copper centres display distorted octahedral geometries and are linked through the two L(1) bridges at a long distance of 8.781(10) Angstrom. The electrochemical behaviour of L(1) was studied in the presence of Ni(2+), Cu(2+), Zn(2+), Cd(2+) and Pb(2+), showing that upon complexation the ferrocene-ferrocenium half-wave potential shifts anodically in relation to that of the free ligand. The maximum electrochemical shift ([capital Delta]E(1/2)) of 268 mV was found in the presence of Pb(2+), followed by Cu(2+)(218 mV), Ni(2+)(152 mV), Zn(2+)(111 mV) and Cd(2+)(110 mV). Moreover, L(1) is able to electrochemically and selectively sense Cu(2+) in the presence of a large excess of the other transition metal cations studied. 相似文献
315.
316.
João Vitor Soares Guilherme Dal Poggetto Renan V. Viesser Uenifer R. Couto Cláudio F. Tormena 《Magnetic resonance in chemistry : MRC》2022,60(5):481-488
Long-range proton-fluorine coupling constants (nJHF) are helpful for the structure elucidation of fluorinated molecules. However, their magnitude and sign can change with the relative position of coupled nuclei and the presence of substituents. Here, trans-4-tert-butyl-2-fluorocyclohexanone was used as a model compound for the study of the transmission of 4JHF. In this compound, the 4JH6axF was measured to be +5.1 Hz, which is five times larger than the remaining 4JHF in the same molecule (4JH4F = +1.0 Hz and 4JH6eqF = +1.0 Hz). Through a combination of experimental data, natural bond orbital (NBO) and natural J-coupling (NJC) analyses, we observed that stereoelectronic interactions involving the π system of the carbonyl group are involved in the transmission pathway for the 4JH6axF. Interactions containing the π system as an electron acceptor (e.g., σC6 H6ax → π*C═O and σC F → π*C═O) increase the value of the 4JH6axF, while the interaction of the π system as an electron donor (e.g., πC═O → σ*C F) decreases it. Additionally, the carbonyl group was shown not to be part of the transmission pathway of the diequatorial 4JH6eqF coupling in cis-4-tert-butyl-2-fluorocyclohexanone, revealing that there is a crucial symmetry requirement that must be fulfilled for the π system to influence the value of the 4JHF in these systems. 相似文献
317.
Prof. Arthur F. P. Alcântara Liniquer A. Fontana Marlon P. Almeida Vitor H. Rigolin Prof. Marcos A. Ribeiro Prof. Wdeson P. Barros Prof. Jackson D. Megiatto Jr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(35):7808-7822
A 5,15-bis(1,1′-biphenyl)porphyrin-based molecular clip covalently connected to a ditopic aliphatic ester loop moiety yields a semi-rigid macrocycle with a well-defined cavity. The resulting macrocycle fits the structural requirements for the preparation of porphyrinates capable of promoting formation of C−C bonds. To demonstrate the usefulness of porphyrin-based macrocycles, an active-metal-template synthesis of rotaxanes through a redox non-innocent carbene transfer reaction is described. Coordination of CoII ions into the porphyrin subunit followed by addition of appropriate monodentate nitrogen-based additives to function as axial ligands enables the radical carbene transfer reactions to styrene derivatives to occur exclusively through the cavity of the macrocycle to afford cyclopropane-linked rotaxanes in excellent 95 % yield. Investigation of the product distribution afforded from the rotaxane assembly reaction reveals how the redox cooperative action between the carbene species and the CoII ions can be manipulated to gain control over the radical-type mechanism to favor the productive rotaxane forming process. 相似文献
318.
Nonlinear Dynamics - Dynamical systems are being employed over the last decades to investigate complex behaviors in traditional fields as engineering and physics, but also in biology, medicine,... 相似文献
319.
Wagner Batista dos Santos Kelly Aparecida Encarnao Amorim Anderson Dourado Galvo Fabricio Tarso Moraes Dario Batista Fortaleza Luiz Alfredo Pavanin 《Photochemistry and photobiology》2019,95(6):1306-1310
Photochemical reactions of ruthenium (II) complexes of type trans‐[Ru(NH3)4LL']2+, where L is a nitrogenous heterocyclic ligand, pyridine (py), isonicotinamide (isn), 4‐acetylpyridine (4‐acpy) or 4‐picoline (4‐pic), and L´ is a 1,2‐bis(4‐pyridyl)ethane (bpa) ligand, were studied with the purpose of evaluating the ligand exchange when, in solution, the complexes are irradiated at the wavelengths of 365, 436, 480 and 519 nm. The study revealed that at lower wavelengths, a labilization process is observed for py and 4‐pic ligands, even at low quantum yields, indicating the dependence of the photolabeling process on the wavelength. The study also reveals that for the filters of greater wavelength, the processes of photolabilization do not occur for any of the studied complexes. The study also shows that there are no photolization processes for the complexes obtained with the isn and 4‐acpy ligands, and it is therefore possible to classify them as nonreactive. 相似文献
320.
Amorim Daniel Roger Bezerra Bellucci Felipe Silva Job Aldo Eloizo Guimarães Iran da Silva da Cunha Helder Nunes 《Journal of Thermal Analysis and Calorimetry》2019,136(4):1615-1629
Journal of Thermal Analysis and Calorimetry - The application of cashew gum, in particular the one which is abundant in northeastern Brazil, remains limited to the foods and pharmaceutics industry.... 相似文献