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221.
Nohara T Iwakawa E Matsushita S Fujiwara Y Ikeda T Miyashita H Ono M Yoshimitsu H 《Chemical & pharmaceutical bulletin》2008,56(7):1013-1014
A new pregnane glycoside, 3-O-beta-lycotetraosyl 5alpha-pregna-3beta,26beta-diol-20-one was isolated from overripe tomato, the fruit of Lycopersicon esculentum MILL. 相似文献
222.
Atsushi Shoji Erika Sugimoto Sayaka Orita Keiichiro Nozawa Akio Yanagida Yoichi Shibusawa Masao Sugawara 《Analytical and bioanalytical chemistry》2010,397(3):1377-1381
We describe a reusable liposome array based on the formation of cleavable disulfide cross-links between liposomes and the
surface of a glass slip. The N-succinimidyl 3-(2-pyridyldithio)-propionate (SPDP)-modified liposomes encapsulating a pH-sensitive fluorescence dye were
immobilized on a 3-mercaptopropyltrimethoxysilane (MTS)-modified glass slip through the formation of disulfide bonds. The
regeneration of a used slip was performed by the lysis of immobilized liposomes with Triton X-100 and the cleavage of disulfide
bonds by reduction with TCEP, followed by immobilization of SPDP-modified liposomes. The regeneration steps did not affect
the fluorescence intensity of re-immobilized liposomes. The liposome array was applied to simultaneous quantification of growth
hormone related peptides, i.e., GHRF and somatostatin, in a mixture. After optimizing the assay condition, the method allowed
quantification of GHRF and somatostatin in concentration ranges from 0.5 × 10−9 to 0.5 × 10−7 g/mL with detection limits of 2 × 10−10 and 3 × 10−10 g/mL, respectively. 相似文献
223.
Shinji Nishikawa Sayaka Kami Nurul Ashikin Badrul Haswan Takahiro Uno Takahito Itoh Masataka Kubo 《Journal of polymer science. Part A, Polymer chemistry》2015,53(5):622-628
Polyfluorenes with pendant allyl groups were prepared by terpolymerization of 9,9‐dihexylfluorene‐2,7‐bis(trimethyleneborate), 2,7‐dibromo‐9,9‐bis(2‐allyloxyethyl)fluorene, and 4,7‐dibromo‐2,1,3‐benzothiazole, or 4,7‐dibromo‐2,1,3‐naphthoselenadiazole using Suzuki coupling reaction. The subsequent hydrosilylation reaction of these precursor polymers with ethoxydimethylsilane quantitatively converted the allyl groups to ethoxysilyl groups. Hybridization of the emitting polyfluorenes with silicone was successfully achieved by the solvent‐free sol–gel reaction of tetraethoxysilane and silanol‐terminated polydimethylsiloxane in the presence of the ethoxysilyl‐functionalized polyfluorenes. Fluorescence spectra of these luminescent silicones revealed that emitting polyfluorenes were dispersed homogeneously in the matrix of silicone without aggregation. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 622–628 相似文献
224.
Tanaka Y Morishima K Shimizu T Kikuchi A Yamato M Okano T Kitamori T 《Lab on a chip》2006,6(3):362-368
Cellular functions are frequently exploited as processing components for integrated chemical systems such as biochemical reactors and bioassay systems. Here, we have created a new cell-based microsystem exploiting the intrinsic pulsatile mechanical functions of cardiomyocytes to build a cellular micropump on-chip using cardiomyocyte sheets as prototype bio-microactuators. We first demonstrate cell-based control of fluid motion in a model microchannel without check valves and evaluate the potential performance of the bio-actuation. For this purpose, a poly(dimethylsiloxane) (PDMS) microchip with a microchannel equipped with a diaphragm and a push-bar structure capable of harnessing collective cell fluid mechanical forces was coupled to a cultured pulsating cardiomyocyte sheet, activating cell-based fluid movement in the microchannel by actuating the diaphragm. Cell oscillation frequency and correlated fluid displacement in this system depended on temperature. When culture temperature was increased, collective cell contraction frequency remained cooperative and synchronous but increased, while displacement was slightly reduced. We then demonstrated directional fluid pumping within microchannels using cantilever-type micro-check valves made of polyimide. A directional flow rate of nL min(-1) was produced. This cell micropump system could be further developed as a self-actuated and efficient mechanochemical transducer requiring no external energy sources for various purposes in the future. 相似文献
225.
Kinoshita H Osamura T Mizuno K Kinoshita S Iwamura T Watanabe S Kataoka T Muraoka O Tanabe G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(14):3896-3904
Reactions between chiral 3-cinnamoyl-4-methyl-5-phenyl-1,3-oxazolidine-2-thiones and aromatic aldehydes in the presence of BF3Et2O diastereoselectively produced tricyclic compounds incorporating a bridgehead carbon bound to four heteroatoms in high yields. Four stereocenters were induced during the reaction. The tricyclic products were transformed into propane-1,3-diols bearing three consecutive stereocenters by acid hydrolysis, S-methylation, and reductive removal of the chiral auxiliary. 相似文献
226.
227.
Masato Matsugi Misaki Suganuma Shoko Yoshida Shohei Hasebe Yoko Kunda Kotaro Hagihara Sayaka Oka 《Tetrahedron letters》2008,49(46):6573-6574
A convenient methodology for the separation of a fluorous by-product using fluorous chemistry is described. A Mukaiyama coupling reagent bearing a medium fluorous tag, between 40% and 60% fluorine by weight, can be effectively separated from non-fluorous components by increasing the water content of the crude reaction mixture and subsequent filtration. Additional fluorous solid phase extraction is not necessary. 相似文献
228.
Ishida Y Sakata H Achalkumar AS Yamada K Matsuoka Y Iwahashi N Amano S Saigo K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(52):14752-14762
Cross-linked polymers prepared by the in-situ polymerization of liquid-crystalline salts were found to work as solid-state hosts with a flexible framework. As a component of such hosts, four kinds of polymerizable amphiphilic carboxylic acids bearing alkyl chains with acryloyloxy (A), dienyl (D), and/or nonreactive (N) chain ends (monomeric carboxylic acids; M(AAA), M(ANA), M(DDD), and M(DND)) were used. The carboxylic acids were mixed with an equimolar amount of a template unit, (1R,2S)-norephedrine (guest amine; G(RS)), to form the corresponding salts. Every salt exhibited a rectangular columnar LC phase at room temperature, which was successfully polymerized by (60)Co γ-ray-induced polymerization without serious structural disordering to afford the salt of cross-linked carboxylic acid (polymeric carboxylic acid; P(AAA), P(ANA), P(DDD), and P(DND)) with G(RS) . Owing to the noncovalency of the interactions between the polymer framework P and the template G(RS), the cross-linked polymers could reversibly release and capture a meaningful amount of G(RS). In response to the desorption and adsorption of G(RS), the cross-linked polymers dramatically switched their nanoscale structural order. A systematic comparison of the polymers revealed that the choice of polymerizable groups has a significant influence on the properties of the resultant polymer frameworks as solid-state hosts. Among these polymers, P(DDD) was found to be an excellent solid-state host, in terms of guest-releasing/capturing ability, guest-recognition ability, durability to repetitive usage, and unique structural switching mode. 相似文献
229.
230.
Hiroshi Watanabe Ming-Long Yao Kunihiro Osaki Toshiyuki Shikata Hirokazu Niwa Yotaro Morishima 《Rheologica Acta》1999,38(1):2-13
Nonlinear rheology was examined for concentrated suspensions of spherical silica particles (with radius of 40 nm) in viscous
media, 2.27/1 (wt/wt) ethylene glycol/glycerol mixture and pure ethylene glycol. The particles were randomly and isotropically
dispersed in the media in the quiescent state, and their effective volume fraction φeff ranged from 0.36 to 0.59. For small strains, the particles exhibited linear relaxation of the Brownian stress σB due to their diffusion. For large step strains γ, the nonlinear relaxation modulus G(t,γ) exhibited strong damping and obeyed the time-strain separability. This damping was related to γ-insensitivity of strain-induced
anisotropy in the particle distribution that resulted in decreases of σB/γ. The damping became stronger for larger φeff. This φeff dependence was related to a hard-core volume effect, i.e., strain-induced collision of the particles that is enhanced for
larger φeff. Under steady/transient shear flow, the particles exhibited thinning and thickening at low and high γ˙, respectively. The thinning behavior was well described by a BKZ constitutive equation using the G(t,γ) data and attributable to decreases of a Brownian contribution, σB/γ˙. The thickening behavior, not described by this equation, was related to dynamic clustering of the particles and corresponding
enhancement of the hydrodynamic stress at high γ˙. In this thickening regime, the viscosity growth η+ after start-up of flow was scaled with a strain γ˙t. Specifically, critical strains γd and γs for the onset of thickening and achievement of the steadily thickened state were independent of γ˙ but decreased with increasing φeff. This φeff dependence was again related to the hard-core volume effect, flow-induced collision of the particles enhanced for larger
φeff.
Received: 26 June 1998 Accepted: 9 December 1998 相似文献