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排序方式: 共有4598条查询结果,搜索用时 15 毫秒
941.
Hirata KS Inoue K Ishida T Kajita T Kihara K Nakahata M Nakamura K Ohara S Sato N Suzuki Y Totsuka Y Yaginuma Y Mori M Oyama Y Suzuki A Takahashi K Yamada M Koshiba M Nishijima K Suda T Tajima T Miyano K Miyata H Takei H Fukuda Y Kodera E Nagashima Y Takita M Kaneyuki K Tanimori T Beier EW Feldscher LR Frank ED Frati W Kim SB Mann AK Newcomer FM Van Berg R Zhang W 《Physical review D: Particles and fields》1991,44(8):2241-2260
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We have used a low energy variational RVB wave function to evaluate the kinetic energy of holons in the dilute limit. We report results on a 5×5 cluster; from the first 8 moments of the density of states, we estimate a lower band edge for the holon, which is fairly insensitive to details of the RVB wave function. This band edge is higher than the corresponding one for a hole in the Néel state, by about 0.08t, in the limitU/t. 相似文献
945.
N. Gunasekara T. Takahashi F. Maeda T. Sagawa H. Suematsu 《Zeitschrift für Physik B Condensed Matter》1988,70(3):349-355
The electronic band structure of the first stage alkali-metal graphite intercalation compounds (C8K, C8Rb and C8Cs) was determined by angle-resolved ultraviolet photoelectron spectroscopy. The dispersive feature of the * bands at
point in the Brillouin zone was clearly observed in all the compounds. The electron occupancies in the * band of C8K, C8Rb and C8Cs were estimated to be 0.5±0.05 e (e; unit electronic charge), 0.45±0.05 e and 0.4±0.05 e, respectively. This strongly suggests that another half of the unit electronic charge is accommodated in the three-dimensional band at point, which forms a spherical Fermi surface at the center of the Brillouin zone. The character of the three-dimensional band at point was also discussed.He died on 27th of September, 1986 相似文献
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Tadayuki Takahashi Tatsuya Ito Seong-Yun Kim 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(3):1067-1073
To separate heat-generating Cs from high-level liquid waste (HLLW), the extraction of Cs(I) using 1,3-[(2,4-diethylheptylethoxy)oxy]-2,4-crown-6-calix[4]arene (calix[4]arene-R14) in combination with 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) ionic liquids ([C n mim][NTf2], where n?=?2, 4, and 6) was investigated. Under moderately acidic conditions, the calix[4]arene-R14/[C n mim][NTf2] system showed a higher extraction efficiency (ECs) than that exhibited by the conventional calix[4]arene-R14/dichloromethane system. All extraction processes reached equilibrium within 5 min. Slope analysis revealed that the Cs:calix[4]arene-R14 inclusion complex has a 1:1 stoichiometry. The extraction was found to be exothermic and influenced by the presence of Na(I). These extraction systems exhibited high efficiency and selectivity for Cs(I) in simulated HLLW. 相似文献
948.
Dr. Kosuke Ono Shunsuke Shimo Dr. Kohei Takahashi Dr. Nobuhiro Yasuda Dr. Hidehiro Uekusa Prof. Nobuharu Iwasawa 《Angewandte Chemie (International ed. in English)》2018,57(12):3113-3117
Dynamic interconversion between large covalent organic cages was achieved simply by heating or acid/base treatment. A mixture of the boroxine cages 12‐mer and 15‐mer was cleanly converted into a pyridine adduct of the 9‐mer boroxine cage upon treatment with pyridine, and the geometry of N‐coordinated boron atoms changed from trigonal to tetrahedral. The reverse reaction was achieved by heating or acid treatment. In this process, the larger boroxine cages 12‐mer and 15‐mer were found to be entropically favored owing to the release of free pyridine molecules from 9‐mer ?6 Py. 相似文献
949.
Utilization of Donor–Acceptor Interactions for the Catalytic Acceleration of Nucleophilic Additions to Aromatic Carbonyl Compounds 下载免费PDF全文
Tatsuhiro Uchikura Dr. Kosuke Ono Dr. Kohei Takahashi Prof. Nobuharu Iwasawa 《Angewandte Chemie (International ed. in English)》2018,57(8):2130-2133
A conceptually new method for the catalytic electrophilic activation of aromatic carbonyl substrates, by utilizing donor–acceptor interactions between an electron‐deficient macrocyclic boronic ester host ( [2+2] BTH‐F ) and an aromatic carbonyl guest substrate, was realized. In the presence of a catalytic amount of [2+2] BTH‐F , dramatic acceleration of the nucleophilic addition of a ketene silyl acetal towards either electron‐rich aromatic aldehydes or ketones was achieved. Several control experiments confirmed that inclusion of the aromatic substrates within [2+2] BTH‐F , through efficient donor–acceptor interactions, is essential for the acceleration of the reaction. 相似文献
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