全文获取类型
收费全文 | 4110篇 |
免费 | 81篇 |
国内免费 | 22篇 |
专业分类
化学 | 2889篇 |
晶体学 | 44篇 |
力学 | 48篇 |
数学 | 184篇 |
物理学 | 1048篇 |
出版年
2022年 | 18篇 |
2021年 | 34篇 |
2020年 | 43篇 |
2019年 | 58篇 |
2018年 | 42篇 |
2017年 | 21篇 |
2016年 | 59篇 |
2015年 | 75篇 |
2014年 | 64篇 |
2013年 | 169篇 |
2012年 | 185篇 |
2011年 | 237篇 |
2010年 | 108篇 |
2009年 | 142篇 |
2008年 | 213篇 |
2007年 | 219篇 |
2006年 | 230篇 |
2005年 | 189篇 |
2004年 | 180篇 |
2003年 | 158篇 |
2002年 | 172篇 |
2001年 | 136篇 |
2000年 | 110篇 |
1999年 | 71篇 |
1998年 | 52篇 |
1997年 | 57篇 |
1996年 | 53篇 |
1995年 | 41篇 |
1994年 | 54篇 |
1993年 | 63篇 |
1992年 | 79篇 |
1991年 | 61篇 |
1990年 | 55篇 |
1989年 | 57篇 |
1988年 | 49篇 |
1987年 | 57篇 |
1986年 | 48篇 |
1985年 | 58篇 |
1984年 | 52篇 |
1983年 | 41篇 |
1982年 | 27篇 |
1981年 | 43篇 |
1980年 | 30篇 |
1979年 | 49篇 |
1978年 | 40篇 |
1977年 | 25篇 |
1976年 | 31篇 |
1975年 | 26篇 |
1974年 | 28篇 |
1973年 | 21篇 |
排序方式: 共有4213条查询结果,搜索用时 15 毫秒
11.
Gui-Chang Wang Ling Jiang Yoshitada Morikawa Junji Nakamura Zun-Sheng Cai Yin-Ming Pan Xue-Zhuang Zhao 《Surface science》2004,570(3):205-217
The adsorption behavior and thermal activation of carbon dioxide on the Cu(1 1 1), Cu(1 0 0), and Cu(1 1 0) surfaces have been investigated by means of density functional theory calculations and cluster models and periodic slabs. According to the cluster models, the optimized results indicate that the basis set of C and O atoms has a distinct effect on the adsorption energy, but an indistinct one on the equilibrium geometry. For the CO2/Cu(hkl) adsorption systems studied here, the final structure of adsorbed CO2 is near linear and the preferred modes for the adsorption of CO2 onto the Cu(1 1 1), Cu(1 0 0), and Cu(1 1 0) surfaces are the side-on adsorption at the cross bridge site with an adsorption energy of 13.06 kJ/mol, the side-on adsorption at the short bridge site (13.54 kJ/mol), and the end-on adsorption on the on-top site with C–O bonds located along the short bridge site (26.01 kJ/mol), respectively. However, the calculated adsorption energies from periodic slabs are lower as compared to the experimental data as well as the cluster model data, indicating that the periodic slab approach of generalized gradient approximation in the density function theory may be not suitable to obtain quantitative information on the interaction of CO2 with Cu(hkl) surfaces. 相似文献
12.
Fumie Takei Daisuke Kodama Sugiko Nakamura Kiyotaka Onitsuka Shigetoshi Takahashi 《Journal of polymer science. Part A, Polymer chemistry》2006,44(1):585-595
Aryl isocyanides bearing free‐base and metallo‐porphyrins were prepared and polymerized with a Pd–Pt μ‐ethynediyl complex as the initiator to give polymers with narrow polydispersity indices. The molecular weights of the resulting polymers were precisely controlled by the initial feed ratio of the porphyrin monomer to the initiator. The UV–VIS spectra suggested that the porphyrin pendants are regularly arranged to form stacked columns. Metallo‐porphyrin polymers were also prepared by reacting free‐base porphyrin polymers with metal salts. The successive reactions of free‐base and zinc‐porphyrin monomers resulted in the formation of diblock polymers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 585–595, 2006 相似文献
13.
Kazuhiko Nakano Toshihiro Nakamura Izumi Nakai Akira Kawase Makoto Imai Mikio Hasegawa Yohichi Ishibashi Isamu Inamoto Kazuhuyu Sudou Masaru Kozaki Akira Tsuruta Akihiro Ono Kazutoshi Kakita Mamoru Sakata 《Analytical sciences》2006,22(9):1265-1268
The Japan Society for Analytical Chemistry has developed some new plastic certified reference materials (CRMs) for the analysis of mercury in polyester disks using XRF analysis. These CRMs (named as JSAC 0621-0625) were prepared by casting polyesters including a toluene solution of organometallic compounds as a standard. Concentrations of the five levels of mercury ranged from 0 to 250 mg/kg. Homogeneity tests of prepared disks had shown excellent results. Interlaboratory comparison study for the certification was performed by 15 laboratory participants. The z-scores in robust statistical method was applied for the evaluation of outliers. The certified values were assigned after discarding outliers. The uncertainties of certified values were determined as the confidence levels of 95%. 相似文献
14.
15.
Bond IA Budding E Conway MJ Fenton KB Fujii H Fujii Z Fujimoto M Hasegawa H Hayashida N Honda M Hotta N Humble JE Kabe S Kasahara K Kifune T Masaike A Matsubara Y Mitsui K Miura Y Mori M Murakami K Muraki Y Nagano M Nakamura K Nakamura T Norris PM Ohashi Y Okada A Saito T Sakata M Sato H Shibata S Shima M Storey JR Tanimori T Teshima M Torii S Uchino K Watase Y Woodhams MD Yamamoto Y Yock PC Yuda T 《Physical review letters》1988,61(20):2292-2295
16.
17.
18.
A linear correlation between the NQR frequency of the terminal iodine atom and the corresponding I-I bond length in I3? was found in several compounds containing triiodide anions. A simple extended Huckel MO calculation suggested that such a correlation can be used to check the validity of wavefunctions of iodine. 相似文献
19.
Tanaka M Nakamura M Ikeda T Ikeda K Ando H Shibutani Y Yajima S Kimura K 《The Journal of organic chemistry》2001,66(21):7008-7012
Synthetic procedures for monoazathiacrown ethers were explored, and monoazatrithia-12-crown-4, monoazatetrathia-15-crown-5, and monoazapentathia-18-crown-6 were obtained in moderate yields by the reaction of bis(2-chloroethyl)amine with the appropriate dithiols in the presence of lithium hydroxide in THF. To evaluate metal-ion binding properties of the monoazathiacrown ethers by solvent extraction, lipophilic dodecyl and dodecanoyl groups were incorporated onto the monoazathiacrown ethers. The solvent extraction experiments suggested that monoazathiacrown ethers have Ag(+) and Hg(2+) selectivities and that the relative selectivity between Ag(+) and Hg(2+) depends on their nitrogen atom properties and numbers of sulfur atoms reflecting the respective affinities of nitrogen and sulfur atoms to Hg(2+) and Ag(+). An interesting ability to bind Mg(2+) was observed in the case of N-dodecyl monoazatrithia-12-crown-4. 相似文献
20.