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621.
Takahiro Sasamori Tomohiro Sugahara Tomohiro Agou Koh Sugamata Jing-Dong Guo Shigeru Nagase Norihiro Tokitoh 《Chemical science》2015,6(10):5526-5530
Reaction of the stable digermyne BbtGeGeBbt (Bbt = 2,6-[CH(SiMe3)2]2-4-[C(SiMe3)3]-C6H2) with ethylene initially afforded the corresponding 1,2-digermacyclobutene. Depending on the reaction conditions applied, further reaction of this 1,2-digermacyclobutene with ethylene furnished two different reaction products: a 1,4-digermabicyclo[2.2.0]hexane or a bis(germiranyl)ethane. Combined experimental and theoretical results suggested that the 1,4-digermabicyclo[2.2.0]hexane and the bis(germiranyl)ethane are the thermodynamic and kinetic reaction products, respectively. A reaction mechanism in agreement with these results was proposed. 相似文献
622.
Dr. Wonsang Koh Hye Sook Moon Prof. Seung Geol Lee Dr. Ji Ii Choi Prof. Seung Soon Jang 《Chemphyschem》2015,16(4):789-795
The mechanism of Li adsorption on a graphene–fullerene (graphene–C60) hybrid system has been investigated using density functional theory (DFT). The adsorption energy for Li atoms on the graphene–C60 hybrid system (?2.285 eV) is found to be higher than that on bare graphene (?1.375 eV), indicating that the Li adsorption on the former system is more stable than on the latter. This is attributed to the high affinity of Li atoms to C60 and the charge redistribution that occurs after graphene is mixed with C60. The electronic properties of the graphene–C60 system such as band structure, density of states, and charge distribution have been characterized as a function of the number of Li atoms adsorbed in comparison to those of the pure graphene and C60. Li adsorption is found to preferentially occur on the C60 side due to the high adsorption energy of Li on C60, which imparts a metallic character to the C60 in the graphene–C60 hybrid system. 相似文献
623.
Jong Kwan Koh Yong Woo Kim Sung Hoon Ahn Byoung Ryul Min Jong Hak Kim 《Journal of Polymer Science.Polymer Physics》2010,48(2):183-189
An amphiphilic comb polymer consisting of poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) [P(VDF‐co‐CTFE)] main chains and poly(oxyethylene methacrylate) (POEM) side chains was synthesized using direct initiation of the chlorine atoms in CTFE units through atom transfer radical polymerization, as confirmed by 1H NMR and FTIR spectroscopy. The P(VDF‐co‐CTFE)‐g‐POEM comb polymer was introduced as an additive to prepare poly(vinylidene fluoride) antifouling ultrafiltration membranes. As the contents of comb polymer increased, the mechanical properties of membranes slightly decreased due to the decreased crystallinity of the membranes, as revealed by universal testing machine and X‐ray diffraction. However, water contact angle measurement and X‐ray photoelectron spectroscopy showed that the hydrophilic POEM segments spontaneously segregated on the membrane surfaces. As a result, the antifouling property of the membranes containing P(VDF‐co‐CTFE)‐g‐POEM comb polymer was considerably improved with a slight change of water flux. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 183–189, 2010 相似文献
624.
LEE JinWuk LIM KwangSoo YOON JungHee RYU DaeWon KOO BongHo KOH EuiKwan HONG ChangSeop 《中国科学:化学(英文版)》2012,55(6):1012-1017
Reaction of unique [W(CN)6(phen)]- with a magnetically anisotropic Mn Schiff base yielded a WⅤ(5d)-MnⅢ(3d) bimetallic compound with a linear chain structure. The magnetic properties of the chain complex feature a ferrimagnetic behavior as well as slow magnetic relaxation typical for a single-chain magnet. 相似文献
625.
Hyuk Yoon Seunghyun Ahn Mijoo Park Dong‐Wook Kim Sang Ho Kim Dongsoo Koh Yoongho Lim 《Magnetic resonance in chemistry : MRC》2013,51(8):500-508
Chalcones are known to act on various physiological targets. As a result, structural modifications of chalcones have been studied extensively. Benzochalcones, in which the A‐ring of chalcone is substituted with a naphthalene unit, inhibits breast cancer resistance protein. Chalcones in which the α,β‐unsaturated carbonyl group is switched with a pyrazoline moiety are potent cytotoxic agents against various cancer cell lines, and chalcones with a pyrazoline‐1‐carbothioamide group instead of an α,β‐unsaturated carbonyl group exhibit antimicrobial activities. The present report describes hybrid molecules designed from benzochalcone and pyrazoline–carbothioamide. Methoxylation of plant‐derived polyphenols alters their hydrophobicity, resulting in changes in biological function and intracellular compartmentation. In the current study, 22 novel methoxylated 3‐(naphthalen‐2‐yl)‐N,5‐diphenyl‐pyrazoline‐1‐carbothioamide derivatives were prepared. This report provides complete assignments of their 1H and 13C NMR data, which can be used to subsequently identify chalcones bearing pyrazoline–carbothioamide groups. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
626.
Sun Woo Shim Doo Yeon Kwon Ji Hoon Park Jae Ho Kim Heung Jae Chun Young Joo Koh Moon Suk Kim 《Journal of polymer science. Part A, Polymer chemistry》2014,52(15):2185-2191
To investigate thermogelling behavior, in this study, we prepared a methoxy poly(ethylene glycol)‐b‐poly(ε‐caprolactone) diblock copolymer (MPC) with varying hydrophobic poly(ε‐caprolactone) (PCL) lengths and an MPC featuring a zwitterionic sulfobetaine (MPC‐ZW) at the chain end of the PCL segment. The terminal zwitterionic sulfobetaine was stoichiometrically modified to the terminal MPC diblock copolymer. The introduction of the zwitterionic end group lowered the crystallization enthalpies of the PCL block segments and increased the solubility of the diblock copolymer. The MPC and MPC‐ZW copolymers thus obtained formed translucent emulsions at room temperature when prepared as 20 wt %. When the temperature was increased above room temperature, MPC and MPC‐ZW exhibited a sol‐to‐gel phase transition. The phase transition and the gelation time of MPC and MPC‐ZW were affected by the length of the hydrophobic segments and the zwitterionic end group. Furthermore, introducing a zwitterionic end group into the PCL segment altered the onset temperature of gelation. Thus, we conclude that zwitterionic end groups introduced into PCL segments of distinct lengths could serve as key determinants in the thermogelling behavior of copolymers. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2185–2191 相似文献
627.
628.
New organic–inorganic composite membranes based on poly(vinylidene fluoride-co-chlorotrifluoroethylene)-graft-poly(styrene sulfonic acid) [P(VDF-co-CTFE)-g-PSSA] with embedded phosphotungstic acid (PWA) were prepared. Fourier transform infrared spectra indicated the existence
of a specific interaction between P(VDF-co-CTFE)-g-PSSA graft copolymer and PWA particles. PWA nanoparticles were well confined in the polymeric matrix up to 20 wt.%, above
which they started to be extracted from the matrix, as revealed by scanning electron microscope analysis. Accordingly, Young’s
modulus of membranes also increased with PWA concentration up to 20 wt.%, above which it continuously decreased. Upon incorporation
of PWA nanoparticles, the proton conductivity of composite membranes slightly decreased from 0.042 to 0.035 S/cm at room temperature
up to 20 wt.%, presumably due to strong interaction between the sulfonic acids of graft copolymer and PWA nanoparticles. The
characterization by thermal gravimetric analysis demonstrated the enhancement of thermal stabilities of the composite membranes
with increasing concentration of PWA. 相似文献
629.
Doseok Hwang Hyuk Yoon Seunghyun Ahn Dong‐Wook Kim Dong‐Ho Bae Dongsoo Koh Yoongho Lim 《Magnetic resonance in chemistry : MRC》2013,51(9):593-599
To find potent new chemotherapy drugs, we designed and synthesized a series of naphthochalcones bearing naphthalenyl‐phenyl‐pyrazoline moieties. The complete 1H and 13C NMR data for these compounds are reported here and can be used to identify further new naphthochalcones bearing the desired pyrazoline moieties. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
630.
Jrg Adams Markus Hollas Myung-Ae Chung Joon Woo Park Ji Hyun Hong Kwanghee Koh Park 《Macromolecular Symposia》1999,142(1):159-172
The influence of the chain conformation on the formation of polymeric supramolecular complexes as well as the influence of the complexation on the conformation of the polymer chain has been studied. The complexation of pyrene into the cavity of β-cyclodextrin (β-CD) was investigated in aqueous solutions of β-CD substituted poly(allylamine) (PAA) under variation of external parameters, i.e. temperature, pH, ionic strength and addition of urea. The observed changes of the complexation constant K for the formation of the 2:1 β-CD/pyrene complex can be explained by a change of the chain flexibility which leads to a variation of the mean distance between neighbouring β-CD-moieties along the polymer chain. The intra-chain association of the decyl group with β-CD in PAA with co-pendant decyl and β-CD is disrupted by the addition of 1-adamantanamine HCl resulting in a more extended structure of the polymer. The β-CD moiety in PAA-CD shows one order of magnitude greater affinity to 2-(p-toluidyl)naphthalene-6-sulfonate than the native β-CD and the affinity increases further by the presence of decyl side groups. 相似文献