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51.
We obtain a local characterization of the point of continuity property for bounded subsets in Banach spaces not containing basic sequences equivalent to the standard basis of ℓ1 and, as a consequence, we deduce that, in Banach spaces with a separable dual, every closed, bounded, convex and nonempty subset failing the point of continuity property contains a further subset which can be seen inside the set of Borel regular probability measures on the Cantor set in a weak-star dense way. Also, we characterize in terms of trees the point of continuity property of Banach spaces not containing ℓ1, by proving that a Banach space not containing ℓ1 satis- fies the point of continuity property if, and only if, every seminormalized weakly null tree has a boundedly complete branch. 相似文献
52.
Dr. Kaizheng Zhu Dr. Ramón Pamies Dr. Nodar Al-Manasir Dr. José Ginés Hernández Cifre Prof. José García de la Torre Prof. Bo Nyström Prof. Anna-Lena Kjøniksen 《Chemphyschem》2020,21(12):1258-1271
The thermoresponsive nature of aqueous solutions of poly(N-isopropylacrylamide) (PNIPAAM) star polymers containing 2, 3, 4, and 6 arms has been investigated by turbidity, dynamic light scattering, rheology, and rheo-SALS. Simulations of the thermosensitive nature of the single star polymers have also been conducted. Some of the samples form aggregates even at temperatures significantly below the lower critical solution temperature (LCST) of PNIPAAM. Increasing concentration and number of arms promotes associations at low temperatures. When the temperature is raised, there is a competition between size increase due to enhanced aggregation and a size reduction caused by contraction. Monte Carlo simulations show that the single stars contract with increasing temperature, and that this contraction is more pronounced when the number of arms is increased. Some samples exhibit a minimum in the turbidity data after the initial increase at the cloud point. The combined rheology and rheo-SALS data suggest that this is due to a fragmentation of the aggregates followed by re-aggregation at even higher temperatures. Although the 6-arm star polymer aggregates more than the other stars at low temperatures, the more compact structure renders it less prone to aggregation at temperatures above the cloud point. 相似文献
53.
The First Heteropentanuclear Extended Metal‐Atom Chain: [Ni+Ru25+Ni2+Ni2+(tripyridyldiamido)4(NCS)2] 下载免费PDF全文
Dr. Min‐Jie Huang Dr. Shao‐An Hua Dr. Ming‐Dung Fu Dr. Gin‐Chen Huang Prof. Caixia Yin Chih‐Hung Ko Dr. Ching‐Kuo Kuo Chia‐Hung Hsu Dr. Gene‐Hsiang Lee Kuan‐Yi Ho Dr. Chia‐Hsin Wang Prof. Yaw‐Wen Yang Prof. I‐Chia Chen Prof. Shie‐Ming Peng Prof. Chun‐hsien Chen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(16):4526-4531
This study develops the first heteropentametal extended metal atom chain (EMAC) in which a string of nickel cores is incorporated with a diruthenium unit to tune the molecular properties. Spectroscopic, crystallographic, and magnetic characterizations show the formation of a fully delocalized Ru25+ unit. This [Ru2]‐containing EMAC exhibits single‐molecule conductance four‐fold superior to that of the pentanickel complex and results in features of negative differential resistance (NDR), which are unobserved in analogues of pentanickel and pentaruthenium EMACs. A plausible mechanism for the NDR behavior is proposed for this diruthenium‐modulated EMAC. 相似文献
54.
Falvello LR Ginés JC Carbó JJ Lledós A Navarro R Soler T Urriolabeitia EP 《Inorganic chemistry》2006,45(17):6803-6815
The phosphorus ylide ligand [Ph3P=C(CO2Me)C(=NPh)CO2Me] (L1) has been prepared and fully characterized by spectroscopic, crystallographic, and density functional theory (DFT) methods (B3LYP level). The reactivity of L1 toward several cationic Pd(II) and Pt(II) precursors, with two vacant coordination sites, has been studied. The reaction of [M(C/\X)(THF)2]ClO4 with L1 (1:1 molar ratio) gives [M(C/\X)(L1)]ClO4 [M = Pd, C/\X = C6H4CH2NMe2 (1), S-C6H4C(H)MeNMe2 (2), CH2-8-C9H6N (3), C6H4-2-NC5H4 (4), o-CH2C6H4P(o-tol)2 (6), eta3-C3H5 (7); M = Pt, C/\X = o-CH2C6H4P(o-tol)2 (5); M(C/\X) = Pd(C6F5)(SC4H8) (8), PdCl2 (9)]. In complexes 1-9, the ligand L1 bonds systematically to the metal center through the iminic N and the carbonyl O of the stabilizing CO2Me group, as is evident from the NMR data and from the X-ray structure of 3. Ligand L1 can also be orthopalladated by reaction with Pd(OAc)2 and LiCl, giving the dinuclear derivative [Pd(mu-Cl)(C6H4-2-PPh2=C(CO2Me)C(CO2Me)=NPh)]2 (10). The X-ray crystal structure of 10 is also reported. In none of the prepared complexes 1-10 was the C(alpha) atom found to be bonded to the metal center. DFT calculations and Bader analysis were performed on ylide L1 and complex 9 and its congeners in order to assess the preference of the six-membered N,O metallacycle over the four-membered C,N and five-membered C,O rings. The presence of two stabilizing groups at the ylidic C causes a reduction of its bonding capabilities. The increasing strength of the Pd-C, Pd-O, and Pd-N bonds along with other subtle effects are responsible for the relative stabilities of the different bonding modes. 相似文献
55.
Two experimentally facile methods for the preparation of discrete oligoethers are reported. The first involves an iterative sequence of oxidation, acetal formation, and reductive ring opening for the synthesis of penta-1,4-butylene glycol. The second method is also iterative, comprising phase-transfer etherification and end-group deprotection to form hexa-1,3-propylene glycol. These methods offer significantly improved yields and purification protocols over previously reported syntheses. 相似文献
56.
Galonić DP Van Der Donk WA Gin DY 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(24):5997-6006
A chemoselective strategy for oligosaccharide-peptide ligation is described in which alpha-thio analogues of mucin-related glycoconjugates can be readily accessed through site-selective conjugate addition of complex oligosaccharide thiolates to dehydroalanine-containing peptides. The efficiency of the ligation is highlighted by the rapid convergent assembly of thio-isosteres of the four tumor-associated carbohydrate antigens, T(N), T, ST(N), and 2,6-ST, as a pair of diastereoisomers at the newly formed cysteine stereocenter. The process proceeds in high yield and with complete retention of the alpha-anomeric configuration. 相似文献
57.
Let
be i.i.d. random variables and let, for each
and
. It is shown that
a.s. whenever the sequence of self-normalized sums S
n
/V
n is stochastically bounded, and that this limsup is a.s. positive if, in addition, X is in the Feller class. It is also shown that, for X in the Feller class, the sequence of self-normalized sums is stochastically bounded if and only if
相似文献
58.
Wang P Kim YJ Navarro-Villalobos M Rohde BD Gin DY 《Journal of the American Chemical Society》2005,127(10):3256-3257
QS-21A is one of the most promising new adjuvants for immune response potentiation and dose-sparing in vaccine therapy, given its exceedingly high level of potency and its favorable toxicity profile. Melanoma, breast cancer, small cell lung cancer, prostate cancer, HIV-1, and malaria are among the numerous maladies targeted in more than 80 recent and ongoing clinical trials involving QS-21A as a critical component for immune response augmentation in microgram doses. Herein is reported the first synthesis and structure verification of QS-21Aapi, applying novel glycosylation methodologies in the convergent modular construction of this rare and potent natural product immunostimulant. 相似文献
59.
Galonić DP Ide ND van der Donk WA Gin DY 《Journal of the American Chemical Society》2005,127(20):7359-7369
The development of a method for site- and stereoselective peptide modification using aziridine-2-carboxylic acid-containing peptides is described. A solid-phase peptide synthesis methodology that allows for the rapid generation of peptides incorporating the aziridine residue has been developed. The unique electrophilic nature of this nonproteinogenic amino acid allows for site-selective conjugation with various thiol nucleophiles, such as anomeric carbohydrate thiols, farnesyl thiol, and biochemical tags, both in solution and on solid support. This strategy, combined with native chemical ligation, provides convergent and rapid access to complex thioglycoconjugates. 相似文献
60.