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421.
Abdulmomem Awwad Patrick Poucheret Yanis A. Idres Damien S. T. Tshibangu Adrien Servent Karine Ferrare Franoise Lazennec Luc P. R. Bidel Guillaume Cazals Didier Tousch 《Molecules (Basel, Switzerland)》2021,26(18)
Plant bioactive extracts represent a major resource for identifying drugs and adjuvant therapy for type 2 diabetes. To promote early screening of plants’ antidiabetic potential, we designed a four in vitro tests strategy to anticipate in vivo bioactivity. Two antidiabetic plants were studied: Ocimum gratissimum L. (Oc) leaf extract and Musanga cecropoides R. Br. ex Tedlie (Mu) stem bark extract. Chemical compositions were analyzed by LCMS and HPLC. Antidiabetic properties were measured based on (1) INS-1 cells for insulin secretion, (2) L6 myoblast cells for insulin sensitization (Glut-4 translocation), (3) L6 myoblast cells for protection against hydrogen peroxide (H2O2) oxidative stress (cell mortality), and (4) liver microsomial fraction for glucose-6-phosphastase activity (G6P). Oc extract increased insulin secretion and insulin sensitivity, whereas it decreased oxidative stress-induced cell mortality and G6P activity. Mu extract decreased insulin secretion and had no effect on insulin sensitivity or G6P activity, but it increased oxidative stress-induced cell mortality. Results were compared with NCRAE, an antidiabetic plant extract used as reference, previously characterized and reported with increased insulin secretion and insulin sensitivity, protection against oxidative stress, and decreased G6P activity. The proposed set of four in vitro tests combined with chemical analysis provided insight into the interest in rapid early screening of plant extract antidiabetic potential to anticipate pharmaco-toxicological in vivo effects. 相似文献
422.
Karine Varlot Jean-Michel Martin Christian Quet Yolande Kihn 《Macromolecular Symposia》1997,119(1):317-324
We have performed EELS analysis of poly (ethylene terephthalate) (PET) in the analytical TEM in order to evaluate the possibility to obtain chemical analysis of the polymer at sub-micrometer scale. Due to irradiation damage, it revealed necessary to work at the lowest possible electron dose, typically below 103 C.m−2, and with the specimen cooled to liquid nitrogen temperature. In the acquired spectra, we propose an identification of the different chemical bondings in agreement with XANES experiments. 相似文献
423.
Yves Grohens Stephane Ulvé Karine Vallée-Réhel Jean Jacques Péron Dominique Haras 《Macromolecular Symposia》2003,203(1):271-276
Contact angle measurements (captive bubble and sessile drop techniques) were used to determine the surface energy of several acrylic based polymers at the early stage of immersion (t0) in pure and salt water or after several days (tx). The sessile drop technique using various liquid probes allows the calculation of the dispersive, acid and basic components of the surface energy. Significant differences of wettability are observed between the polymers at t0 which tend to remain after immersion along with a general increase of the surface hydrophilicity. The same trend is observed by the “in-situ” captive bubble technique. The surfaces become more hydrophilic with a final contact angle, θ, ranging from 110 to 150 ± 3° in pure water and 130 to 150 ± 4° in 0,51 M salt water. The modifications of surface energy between t0 and tx are not only dependent on water diffusion. One assumption is that the degree of swelling of the immersed surface layer along with the particular dynamics resulting from a surface gel-like structure are significant factors in the measured surface thermodynamics. 相似文献
424.
Karine Khougaz Matthew Moffitt Lifeng Zhang Adi Eisenberg 《Macromolecular Symposia》1996,106(1):435-438
Analogous to the self-assembly of low-molecular-weight amphiphiles in aqueous solutions, the formation of spherical micelle-like aggregates has been observed in systems of amphiphilic block copolymers in water. The aggregates, often called micelles due to structural similarities with surfactant associates, are found to exist above the critical micelle concentration (cmc). The micellization of amphiphilic block copolymers has been investigated using a wide range of techniques, such as size-exclusion chromatography (SEC), static and dynamic light scattering (SLS and DLS), small-angle x-ray scattering (SAXS), small-angle neutron scattering (SANS), transmission electron microscopy (TEM), viscometry, and steady-state fluorescence spectroscopy. The present lecture is a review of recent work in our laboratory concerning the micellization of ionic block copolymers. These high-molecular-weight amphiphiles may contain one or more of a variety of ionic blocks, such as poly(4-vinylpyridinium alkyl halides), poly(metal acrylates), poly(metal methacrylates) and sulfonated polystyrene. In water, such polymers are referred to as block polyelectrolytes, as they combine the colloidal behavior of block copolymers with the long-range electrostatic interactions of polyelectrolytes. Early work in this field has been reviewed by Selb and Gallot.1 相似文献
425.
426.
Dr. Julia Sabalot-Cuzzubbo Dr. William Lafargue-Dit-Hauret Prof. Dr. Michel Rérat Dr. Karine Costuas Prof. Dr. Didier Bégué Prof. Dr. Jacky Cresson 《Chemphyschem》2023,24(12):e202200951
Herein, we deeply detail for the very first time mathematical concepts behind the generation of helical molecular orbitals (MOs) for linear chains of atoms. We first give a definition of helical MOs and we provide an index measuring how far a given helical states is from a perfect helical distribution. Structural properties of helical distribution for twisted -cumulene and cumulene version of Möbius systems are given. We then give some simple structural assumptions as well as symmetry requirements ensuring the existence of helical MOs. Considering molecules which do not admit helical MOs, we provide a first way to induce helical states by the breaking of symmetries. We also explore an alternative way using excited conformations of given molecules as well as different electronic multiplicities. 相似文献