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991.
Benjamin Sierra-Martin Jorge Rubio Retama Marco Laurenti Antonio Fernández Barbero Enrique López Cabarcos 《Advances in colloid and interface science》2014
The synthesis of temperature-responsive microgels of poly(N-isopropylacrylamide) (PNIPAM) was first reported in 1986 and, since then, there have been hundreds of publications describing the preparation, characterization and applications of these systems. This paper reviews the developments concerning the study of the structure of PNIPAM-based microgels performed over the last years using small angle neutron scattering (SANS) and also the investigations of the polymer-chain dynamics within the microgels carried out with incoherent elastic and quasielastic neutron scattering, and pulse field gradient nuclear magnetic resonance (PFG-NMR) techniques. Furthermore, the self-diffusion coefficient of the water molecules within the microgel, determined by means of solvent relaxation NMR, is also discussed as a function of the polymer volume fraction of the microgels. 相似文献
992.
In this paper, we consider the evolution of the so-called vortex filament equation (VFE), taking a planar regular polygon of M sides as initial datum. We study VFE from a completely novel point of view: that of an evolution equation which yields a very good generator of pseudorandom numbers in a completely natural way. This essential randomness of VFE is in agreement with the randomness of the physical phenomena upon which it is based.
相似文献
$$\mathbf{X}_t = \mathbf{X}_s\wedge\mathbf{X}_{ss}, $$
993.
Enrique Alvarez-Manzaneda Rachid ChahbounEsteban Alvarez Ramón Alvarez-ManzanedaPedro E. Muñoz Fermín JiménezHanane Bouanou 《Tetrahedron letters》2011,52(31):4017-4020
The treatment of 2,3-epoxy primary alcohols with lead(IV) acetate (LTA) leads to α-acetoxy aldehydes or α-acetoxy ketones, through the nucleophilic ring-opening of an intermediate oxonium and the subsequent carbon-carbon bond cleavage. This reaction represents a new route to optically active α-hydroxy carbonyl compounds. 相似文献
994.
995.
996.
Balbina P. García-Aguilar Antonio Avalos Ramirez J. Peter Jones Michèle Heitz 《Chemical Papers》2011,65(3):373-379
The emissions of methane (CH4), a powerful greenhouse gas (GES), contribute to the increase in GES concentration level in the atmosphere. For this reason,
the importance of controlling CH4 emissions of anthropogenic origin has increased over the last decades. Physicochemical and biological processes are available
for treating CH4. For this reason, such properties as the solubility of CH4 in aqueous solutions and organic solvents are of great relevance in different applications in environmental engineering and
biotechnology. In this study, the solubility of CH4 was determined at 298 K and 101.3 kPa in organic solvents, such as polyoxyethylenesorbates (Tween 20, Tween 40, and Tween
60), and linear alcohols (methanol, ethanol, and butan-1-ol) alone and in their admixtures. Admixtures of methanol with butan-1-ol
exhibited the highest solubility of CH4, of around 0.49 g m−3 of solvent, whereas the solubility of CH4 in linear alcohols varied from 0.167 g m−3 to 0.41 g m−3 of solvent. In the case of Tweens, CH4 solubility decreased with the hydrophilic-lipophilic balance (HLB) number. 相似文献
997.
Justicia J Álvarez de Cienfuegos L Campaña AG Miguel D Jakoby V Gansäuer A Cuerva JM 《Chemical Society reviews》2011,40(7):3525-3537
This tutorial review highlights the development of radical-based bioinspired synthesis of terpenes from the initial proposal to the development of modern catalytic methods for performing such processes. The power of the radical approach is demonstrated by the straightforward syntheses of many natural products from readily available starting materials. The efficiency of these processes nicely complements the described cationic polyolefin cyclisations and even suggests that modern radical methods provide means to improve upon nature's synthetic pathways. 相似文献
998.
Jiménez-Millán E Giner-Casares JJ Muñoz E Martín-Romero MT Camacho L 《Langmuir : the ACS journal of surfaces and colloids》2011,27(24):14888-14899
The surface active derivative of the organic dye Acridine Orange (N-10-dodecyl-acridine orange (DAO)) has been included in mixed Langmuir monolayers with stearic acid (SA). The maximum relative content on DAO for a stable mixed monolayer is a molar ratio of X(DAO) = 0.5. Brewster angle microscopy (BAM) reveals a high homogeneity at the micrometer level for the mixed monolayer in equimolar proportion (X(DAO) = 0.5), whereas the appearance of domains occurs for lower content of DAO, i.e., X(DAO) = 0.2 and 0.1. The aggregation of the DAO headgroup leads to well-defined H-aggregates at the air/water interface for those mixed monolayers with a low content of DAO. However, for the mixed monolayers enriched in DAO, e.g., X(DAO) = 0.5, the molecular crowding prevents the formation of defined supramolecular structures. Molecular organization and tilting of the DAO headgroup is quantitatively analyzed by in situ UV-visible reflection spectroscopy. The formation of H-aggregates of the DAO headgroup can be reversibly tuned with the applied surface pressure. A molecular mechanism for the conformational rearrangement of the DAO molecule is proposed using RM1 quantum semiempirical calculations. 相似文献
999.
Contreras-Cáceres R Abalde-Cela S Guardia-Girós P Fernández-Barbero A Pérez-Juste J Alvarez-Puebla RA Liz-Marzán LM 《Langmuir : the ACS journal of surfaces and colloids》2011,27(8):4520-4525
We report on the fabrication of a SERS substrate comprising magnetic and silver particles encapsulated within a poly(N-isopropylacrylamide) (pNIPAM) thermoresponsive microgel. This colloidal substrate has the ability to adsorb analytes from solution while it is expanded (low temperature) and reversibly generate hot spots upon collapse (high temperature or drying). Additionally, the magnetic functionality permits concentration of the composite particles into small spatial regions, which can be exploited to decrease the amount of material per analysis while improving its SERS detection limit. Proof of concept for the sequestration of uncommon molecular systems is demonstrated through the first SERS analysis of pentachlorophenol (PCP), a chlorinated ubiquitous environmental pollutant. 相似文献
1000.
Vega ED Lomsadze K Chankvetadze L Salgado A Scriba GK Calvo E López JA Crego AL Marina ML Chankvetadze B 《Electrophoresis》2011,32(19):2640-2647
The enantiomer migration order (EMO) of ephedrine was investigated in the presence of various CDs in CE. The molecular mechanisms of chiral recognition were followed for the ephedrine complexes with native α- and β-CD and heptakis(2,3-di-O-acetyl-6-O-sulfo)-β-CD (HDAS-β-CD) by CE, NMR spectroscopy and high-resolution MS. Minor structural differences were observed between the complexes of ephedrine with α- and β-CD although the migration order of enantiomers was opposite when these two CDs were applied as chiral selectors in CE. The EMO was also opposite between β-CD and HDAS-β-CD. Significant structural differences were observed between ephedrine complexes with the native CDs and HDAS-β-CD. The latter CD was advantageous as chiral CE selector not only due to its opposite electrophoretic mobility compared with that of the cationic chiral analyte, but also primarily due to its enhanced chiral recognition ability towards the enantiomers of ephedrine. 相似文献