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51.
In this paper, we study the dynamics of predator-prey interaction systems between two species with ratio-dependent functional responses. First we provide sufficient and necessary conditions for positive steady-state solutions, and then we investigate the relationships between positive equilibria and positive solutions of the system over a large domain. Furthermore, we deal with the uniqueness and the stability of positive steady-states solutions with some assumptions. In addition, we discuss the extinction and the persistence results of time-dependent positive solutions to the system. 相似文献
52.
Inorganic species formation in a discharged water generating (DWG) system consisting of a plane-to-plane electrode arrangement with a 20 kV, 20 mA and 1 kHz power source has been investigated. The DWG system is able to produce the various oxidants HNO2, HNO3 and O3, as well as OH radicals and many other unconfirmed radicals. These products can play an important role in the advanced oxidation of organic compounds and in rot protection. The pH of water discharged from the system for 20 min during inflow of natural air was about 3, nitrogen concentrations of nitrite and nitrate were 4.6 mg/L and 7.9 mg/L, respectively, residual dissolved ozone concentration was 0.7 mg/L and the oxidation power as measured by KI titration methods was approximately equivalent to 46 mg-O3/L. 相似文献
53.
Chul-Joong Kim Hyeon-Yeol Ryu Somin Lee Han-Joo Lee Yoon-Soek Chun Jong-Kyu Kim Chang-Yeon Yu Bimal Kumar Ghimire Jae-Geun Lee 《Molecules (Basel, Switzerland)》2021,26(10)
Wild ginseng has better pharmacological effects than cultivated ginseng. However, its industrialization is limited by the inability to grow wild ginseng on a large scale. Herein, we demonstrate how to optimize ginseng production through cultivation, and how to enhance the concentrations of specific ginsenosides through fermentation. In the study, we also evaluated the ability of fermented cultured wild ginseng root extract (HLJG0701-β) to inhibit acetylcholinesterase (AChE), as well as its neuroprotective effects and antioxidant activity. In in vitro tests, HLJG0701-β inhibited AChE activity and exerted neuroprotective and antioxidant effects (showing increased catalyst activity but decreased reactive oxygen species concentration). In in vivo tests, after HLJG0701-β was orally administered at doses of 0, 125, 250, and 500 mg/kg in an animal model of memory impairment, behavioral evaluation (Morris water maze test and Y-maze task test) was performed. The levels of AChE, acetylcholine (ACh), blood catalase (CAT), and malondialdehyde (MDA) in brain tissues were measured. The results showed that HLJG0701-β produced the best results at a dose of 250 mg/kg or more. The neuroprotective mechanism of HLJG0701-β was determined to involve the inhibition of AChE activity and a decrease in oxidative stress. In summary, both in vitro and in vivo tests confirmed that HJG0701-β administration can lead to memory improvement. 相似文献
54.
Sung-Sik You Hyeong-Won Ryu Young Cho Dae-Young Kim Thong-Sung Ko 《Reaction Kinetics and Catalysis Letters》1999,66(1):121-126
The nonenzymatic hydrolysis of RNA by polyvinylpyrrolidone (PVP) has been investigated. A bell-shaped kinetics was observed
when the first order rate constant of the reaction was ploted as a function of PVP concentration, which means the kinetic
feature of PVP as a degradative receptor distinct from those of degradative enzymes (e.g., ribonuclease). 相似文献
55.
Yunhua Yu Qing Yang Donghua Teng Xiaoping Yang Seungkon Ryu 《Electrochemistry communications》2010,12(9):1187-1190
Reticular tin nanoparticle-dispersed carbon (Sn/C) nanofibers were fabricated by stabilization of electrospun SnCl4/PAN composite fibers and subsequent carbonization at different temperatures. These Sn/C composite nanofibers used as anode materials for rechargeable lithium-ion batteries (LIBs) show that the Sn/C nanofibers at 700 and 850 °C present much higher charge (785.8 and 811 mA h g?1) and discharge (1211.7 and 993 mA h g?1) capacities than those at 550 and 1000 °C and the as-received CNFs at 850 °C, corresponding to coulombic efficiencies of 64.9% and 81.7%, respectively. The superior electrochemical properties of the intriguing Sn/C nanofibers indicate a promising application in high performance Li-ion batteries. 相似文献
56.
Seong Ho Ryu 《Liquid crystals》2016,43(13-15):1951-1972
ABSTRACTThe orientation control of liquid crystal (LC) phases is essential for fundamental studies as well as practical applications. Surface treatment and topographic confinement have emerged as two of the most effective tools to control ordering and orientation of various types of LC phases. This review is intended to give an overview of the LC phases controlled in confined geometries at micro- and nanometre scales, in which the orientation control methods and the effective analytical techniques will be covered. Finally, the review closes with the applications using such confined LC phases. 相似文献
57.
Takeshi Kimura Shinya Ito Takashi Sasaki Satoshi Ogawa Ryu Sato Yasushi Kawai 《Heteroatom Chemistry》2008,19(4):394-401
4,9‐Diethyl[1,4]dihydrodithiino[5,6‐f]benzotrithiole (DTBT) gave a radical cation, DTBT(•+), and a dication, DTBT(2+), on treatment with a single‐electron oxidizing reagent. Both compounds showed an ESR signal, whereas the dication, generated by this procedure, was silent for 1H NMR. Hydrolysis of DTBT(2+) gave DTBT 1‐oxide (DTBT 1‐O) and 2‐oxide (DTBT 2‐O) together with DTBT and a mixture of several dioxides. A singlet‐state dication, DTBT(2+)‐S, which was generated upon treatment of DTBT 5‐oxide (DTBT 5‐O) with concentrated D2SO4, was detected by 1H and 13C NMR. After 20 h, the NMR signals disappeared while the solution was active for ESR. The results suggest that (i) a species generated from DTBT by oxidation with the single‐electron oxidizing reagent is a triplet‐state dication, DTBT(2+)‐T, and (ii) DTBT(2+)‐S, initially generated, gradually isomerizes to DTBT(2+)‐T in the solution, and DTBT(2+)‐T forms a partial spin pair. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:394–401, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20445 相似文献
58.
In this study, a facultative bacterium that converts fumarate to succinate at a high yield was isolated. The yield of biocon
version was enhanced about 1.2 times by addition of glucose into culture medium at an initial concentration of 6 g/L. When
the initial cell density was high (2 g/L), the succinate produced at pH 7.0 for initial fumarate concentrations of 30, 50,
80, and 100 g/L were 29.3, 40.9, 63.6, and 82.5 g/L, respectively, showing an increase with the initial fumarate concentration.
The high yield of 96.8%/mole of fumarate in just 4 h was obtained at the initial fumarate concentration of 30 g/L. Comparing
these values to those obtained with low cell culture (0.2 g/L), we found that the amount of succinate produced was similar,
but the production rate in the high cell culture was about three times higher than was the case in the low cell culture. This
strain converted fumarate to succinate at a rate of 3.5 g/L·h under the sparge of CO2. 相似文献
59.
60.
Sung‐Nak Choi Sang‐Yub Kim Hae‐Wook Ryu Yong‐Min Lee 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(12):m504-m506
In the title compound, [HgCl2(C15H26N2)], the chiral alkaloid (6R,7S,8S,14S)‐(−)‐l ‐sparteine acts as a bidentate ligand, with two Cl− ligands occupying the remaining coordination sites, producing a distorted tetrahedron. The N—Hg—N plane is twisted by 81.1 (2)° from the Cl—Hg—Cl plane. The mid‐point of the N⋯N line does not lie exactly on the Cl—Hg—Cl plane but is tilted towards one of the N atoms by 0.346 Å. Similarly, the mid‐point of the Cl⋯Cl line is tilted toward one of the Cl atoms by 0.163 Å. The packing structure shows that the complex is stabilized by two interatomic Cl⋯H contacts involving both Cl atoms and the methylene or methine H atoms of the (−)‐sparteine ligand. 相似文献