全文获取类型
收费全文 | 1663篇 |
免费 | 47篇 |
国内免费 | 3篇 |
专业分类
化学 | 1108篇 |
晶体学 | 9篇 |
力学 | 54篇 |
数学 | 312篇 |
物理学 | 230篇 |
出版年
2023年 | 8篇 |
2022年 | 18篇 |
2021年 | 20篇 |
2020年 | 18篇 |
2019年 | 16篇 |
2018年 | 17篇 |
2017年 | 16篇 |
2016年 | 34篇 |
2015年 | 37篇 |
2014年 | 45篇 |
2013年 | 85篇 |
2012年 | 127篇 |
2011年 | 117篇 |
2010年 | 92篇 |
2009年 | 83篇 |
2008年 | 109篇 |
2007年 | 120篇 |
2006年 | 99篇 |
2005年 | 92篇 |
2004年 | 81篇 |
2003年 | 60篇 |
2002年 | 67篇 |
2001年 | 21篇 |
2000年 | 23篇 |
1999年 | 20篇 |
1998年 | 19篇 |
1997年 | 17篇 |
1996年 | 14篇 |
1995年 | 9篇 |
1994年 | 26篇 |
1993年 | 16篇 |
1992年 | 8篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 14篇 |
1984年 | 14篇 |
1983年 | 7篇 |
1982年 | 14篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 10篇 |
1978年 | 12篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1975年 | 8篇 |
1974年 | 7篇 |
1972年 | 4篇 |
排序方式: 共有1713条查询结果,搜索用时 0 毫秒
101.
Gabriela Ruiz-Montañez Montserrat Calderón-Santoyo Dominique Chevalier-Lucia Laetitia Picart-Palmade Darvin Ervey Jimenez-Sánchez 《Journal of Dispersion Science and Technology》2013,34(10):1507-1515
The aim of the article was to develop stable and safe eco-friendly microcapsules and evaluate their physicochemical properties and their efficiency to protect a jackfruit extract. Eco-friendly microcapsules were produced by ultrasound and spray drying using only three safe ingredients: sucrose ester (SE), miglyol and maltodextrin (DE = 10). Some physicochemical properties, particle morphology, FT-IR, differential scanning calorimetry and antiproliferative activity were determined for microcapsules loaded or not with the jackfuit extract. The results revealed that the encapsulation process by spray drying produced stable microcapsules, with adequate physicochemical and fluid properties for a powder product. The cell viability on the proliferation of M12.C3.F6 cell line was not affected by powder microcapsules without jackfruit extract, indicating that capsules are not toxic for these cells. However, microcapsules with jackfruit extract (100 μg/ml) were able to inhibit significantly the proliferation of M12.C3.F6 cells. These microcapsules can be used for the protection of different compounds sensitive to light, oxygen and/or heat and displaying a very low aqueous solubility. 相似文献
102.
Alain ValtzChien-Bin Soo Christophe Coquelet Dominique RichonDaniel Amoros Hubert Gayet 《Fluid Phase Equilibria》2011,309(1):15-19
To simulate cyclohexane to cyclohexanol oxidation reactors, the acquisition and modeling of vapor-liquid equilibria of the key components, under the process conditions, are essential. n-Hexanoic acid is a co-product of the reaction. Vapor-liquid equilibrium data are reported for the cyclohexane + n-hexanoic acid binary system at four temperatures: 413, 423, 464 and 484 K. All measurements have been carried out using an apparatus based on the “static-analytic” method, with two ROLSI™ pneumatic capillary samplers. The generated data are successfully correlated using two equations of state, the Peng-Robinson (PR) and the Perturbed Chain Statistical Association Fluid Theory (PC-SAFT). Both models are capable of representing the experimental data, but the PC-SAFT EoS uses less binary interaction parameters. 相似文献
103.
Chengcheng Yang Valter Castelvetro Dominique Scalarone Sabrina Bianchi Yongming Zhang 《Journal of polymer science. Part A, Polymer chemistry》2011,49(21):4518-4530
Stable colloidal dispersions of nanostructured semifluorinated acrylic particles with an unfluorinated core and an outer layer consisting of copolymers of the highly hydrophobic and lipophobic heptadecafluorodecyl methacrylate (FMA) were successfully synthesized with the assistance of three different cyclodextrins as phase‐transfer catalysts: β‐cyclodextrin (β‐CD), hydroxypropyl β‐cyclodextrin (HpCD), and methyl β‐cyclodextrin (MeCD). While all the cyclodextrins form a stable inclusion complex (IC) with FMA, only the ICs with the more hydrophilic HpCD and MeCD are soluble in water. Nevertheless, incorporation of FMA in the particle shell copolymer could be achieved also when using β‐CD. On the other hand, the morphology of the nanostructured particles was characterized by a “patchy” fluorinated shell dependent on the cyclodextrin used, the best results being obtained with MeCD. A monomer‐starved semicontinuous emulsion polymerization procedure was essential to favor the CD‐mediated incorporation of FMA into the copolymer structure and to achieve a stable colloidal dispersion even in the presence of small amounts of mixed anionic–nonionic surfactants. The thermal and surface properties of the latex films showed a good correlation with the shell composition and patchy nanostructured morphology of the particles. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
104.
1. INTRODUCTION Streptococcus pneumoniae remains an important cause of infections in this end of the 20th century and is responsible for invasive diseases - pneumonia, meningitis, bacteremia, septicemia - as well as for noninvasive diseases such as pharyngitis, conjunctivitis, otitis media.1,2 相似文献
105.
Sarah Djabarouti Pierre Duffau Fabien Xuereb Estibaliz Lazaro Carine Greib Jean-Baptiste Gordien Olivier Caubet Marie-Claude Saux Jean-François Viallard Jean-Luc Pellegrin Dominique Breilh 《Chromatographia》2009,70(5-6):939-945
Liquid chromatography coupled with mass spectrometry for the determination of total and unbound mycophenolic acid and its major metabolite in human plasma has been developed. Sample preparations were based on a fully automated solid-phase extraction process and ultrafiltration. Mass spectrometric data were acquired in a single-ion monitoring method. The analytes and nevirapine (internal standard) were well separated in an isocratic mode over 8 min. Validation study exhibited excellent linearity, with intra- and inter-day precision and accuracy of less than 12%. The assay was successfully applied to the pharmacokinetic study of mycophenolic acid in patients with autoimmune diseases. 相似文献
106.
The Cr 2p and O 1s binding energy (BE) levels have been calculated by first principles methods for different models of hydroxylated (0001)-Cr2O3 surfaces. Several surface terminations have been considered. The calculations allow us to reproduce the O 1s shifts between O in oxide and OH groups. It is found that two main effects account for the OH binding energy shifts. On the one hand, the increased covalency of the O–H bond with respect to the Cr–O bond, lowers the electronic O (1s and 2p) energy, and in consequence the BE of the core levels (O 1s) are higher. On the other hand, the lower the OH coordination number, the higher the valence and core levels energy, and the lower the BE. Consequently, mono-coordinated hydroxyls have a binding energy near that of O2? in the oxide (ΔBEOH–O = ? 0.2–0.0 eV). Two-fold coordinated hydroxyls have a slightly higher BE (ΔBEOH–O = + 0.3 eV). Three-fold coordinated OH groups have a higher binding energy (ΔBEOH–O = + 0.6?0.7 eV), corresponding to that experimentally measured for OH groups. Finally, water adsorbed above OH groups exhibits a still higher BE (ΔBEHOH–O = + 0.9–1.0 eV). The ΔBE are slightly under-estimated under the initial state approximation, and overestimated under the final state (Z + 1) approximation. 相似文献
107.
In this article, we begin a systematic study of conformal properties of codimension-1 foliations. We first define and study
local conformal invariants. A case of particular interest is that of harmonic foliations of the plane. Then we study existence
of totally umbilical and “Dupin” foliations on compact 3-manifolds of constant curvature.
相似文献
108.
Dominique Petit Jean-Pierre Korb Pierre Levitz Jean LeBideau David Brevet 《Comptes Rendus Chimie》2010,13(4):409-411
We present the first results of the nuclear magnetic relaxation dispersion (NMRD) of the confined proton-bearing cation (BMI) and fluorine-bearing anion (TFSI) pair of ionic liquids (Li+-ionogels) confined within a silica-like mesoporous matrices designed for lithium batteries. These results are in favour of a very-correlated dynamical motion of the anion–cation pair within the solid and disordered silica matrix. 相似文献
109.
110.
We study the relationship between two classical approaches for quantitative ergodic properties: the first one based on Lyapunov type controls and popularized by Meyn and Tweedie, the second one based on functional inequalities (of Poincaré type). We show that they can be linked through new inequalities (Lyapunov-Poincaré inequalities). Explicit examples for diffusion processes are studied, improving some results in the literature. The example of the kinetic Fokker-Planck equation recently studied by Hérau and Nier, Helffer and Nier, and Villani is in particular discussed in the final section. 相似文献