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151.
A rhodium-catalyzed asymmetric addition of readily available potassium organotrifluoroborates to both N-tosyl and N-nosyl ketimines has been developed. High enantioselectivity has been achieved by using a chiral diene ligand, and the nosyl group of the addition products can be easily removed while retaining the enantiomeric purity. 相似文献
152.
Zhao Z Matsunami K Otsuka H Shinzato T Takeda Y 《Chemical & pharmaceutical bulletin》2011,59(7):902-905
From the 1-BuOH-soluble fraction of a MeOH extract of leaves of Tarenna gracilipes, collected in Okinawa, six further new cycloartane glycosides, named tareciliosides H-M (1-6), were isolated. Their structures were established through a combination of spectroscopic analyses. 相似文献
153.
Amaya T Hifumi M Okada M Shimizu Y Moriuchi T Segawa K Ando Y Hirao T 《The Journal of organic chemistry》2011,76(19):8049-8052
Oxosumanenes were synthesized through benzylic oxidation. The electronic and redox properties were revealed to exhibit the expanded π-conjugation compared to sumanene. Single-crystal X-ray analysis of monooxosumanene showed columnar π-stacking in a concave-convex fashion. Stereoselective trimethylation of the trioxo derivative was performed via 1,2-addition to the carbonyl groups. 相似文献
154.
Imoto M Matsui Y Takeda M Tamaki A Taniguchi H Mizuno K Ikeda H 《The Journal of organic chemistry》2011,76(15):6356-6361
Observations show that nitroanilines exhibit an unusually high S(N)Ar reactivity with OH(-) in aqueous media in reactions that produce nitrophenols. S(N)Ar reaction of 4-nitroaniline (2a) in aqueous NaOH for 16 h yields 4-nitrophenol (4a) quantitatively, whereas a similar reaction of 4-nitrochlorobenzene (1a) gave 4a in 2% yield together with recovered 1a in 97%, suggesting that the leaving ability of the NH(2) group far surpasses that of Cl under these conditions. An essential feature of S(N)Ar reactions of nitroanilines is probably that the NH(2) leaving group participates in a hydrogen-bonding interaction with H(2)O. Density functional theory (DFT) calculations for a set of 4-nitroaniline, OH(-), and H(2)O suggest a possible formation of a Meisenheimer complex stabilized by hydrogen-bonding interactions and a six-membered ring structure. The results obtained here contrast with conventional S(N)Ar reactivity profiles in which nitroanilines are nearly unreactive with nucleophiles in organic solvents. 相似文献
155.
Nakabayashi K Amemiya F Fuchigami T Machida K Takeda S Tamamitsu K Atobe M 《Chemical communications (Cambridge, England)》2011,47(20):5765-5767
A new technique for the preparation of a highly clear and transparent emulsified aqueous solution containing immiscible monomer droplets with diameters of a few tens of nanometres under surfactant-free conditions using tandem acoustic emulsification is described. Highly conductive transparent polymer films were successfully prepared from such an emulsified solution. 相似文献
156.
Xie Jian Imanishi Nobuyuki Hirano Atsushi Takeda Yashuo Yamamoto Osamu Zhao Xin-Bing Cao Gao-Shao 《Journal of Solid State Electrochemistry》2011,15(9):2031-2039
Ag and Ag2O thin films have been prepared by radio frequency magnetron sputtering on Cu substrates and have been characterized by X-ray
diffraction, scanning electron microscope and atomic force microscope. The electrochemical performance of the thin films has
been studied by galvanostatic cycling and cyclic voltammetry. The potential dependence of Li-ion chemical diffusion coefficients,
[(D)\tilde]\textLi {\widetilde{D}_{\text{Li}}} , of the films has been determined by galvanostatic intermittent titration technique and electrochemical impedance spectroscopy.
It is found that Li-ion chemical diffusion coefficients of the Ag film range from 10−16 to 3 × 10−14 cm2 s−1. The Ag/Li2O composite that is formed from Ag2O after the first cycle exhibits higher
[(D)\tilde]\textLi {\widetilde{D}_{\text{Li}}} values than the Ag film, especially at a low Li-intercalation content. The phase transitions in the two-phase region cause
a significant decrease of chemical diffusion coefficients. 相似文献
157.
158.
Akira Kaito Masaki Shimomura Michiaki Akaba Shuichi Nojima 《Journal of Polymer Science.Polymer Physics》2007,45(15):1959-1969
Real‐time small‐angle X‐ray scattering (SAXS) measurement using synchrotron radiation was applied to study the lamellar structural changes in miscible crystalline polymer blends of poly(1,4‐butylene succinate) (PBSU) and poly(vinylidene fluoride) (PVDF) during melting and crystallization processes. The lamella of PBSU is either included in the interlamellar region of PVDF (interlamellar inclusion structure), or rejected from the interlamellar region of PVDF (interlamellar exclusion structure). The two lamellar structures coexists in the melt‐quenched samples of the PBSU/PVDF = 30/70 blend. Only the interlamellar exclusion structure exists in the drawn films of the PBSU/PVDF = 30/70 blend. The real‐time SAXS results show that the interlamellar exclusion structure in these samples is irreversibly transformed into the interlamellar inclusion structure by heating the sample above the melting temperature of PBSU and that the PBSU chains are crystallized between the lamellae of PVDF during the cooling process. The factors controlling the lamellar structural changes are possibly a balance of the miscibility and the chain exclusion by tie‐molecules and/or the chain diffusion under confinement by the lamellae of PVDF with higher melting temperature. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1959–1969, 2007 相似文献
159.
K Kakiuchi M Ue M Takeda T Tadaki Y Kato T Nagashima Y Tobe H Koike N Ida Y Odaira 《Chemical & pharmaceutical bulletin》1987,35(2):617-631
160.