全文获取类型
收费全文 | 699篇 |
免费 | 7篇 |
国内免费 | 2篇 |
专业分类
化学 | 558篇 |
晶体学 | 11篇 |
力学 | 10篇 |
数学 | 50篇 |
物理学 | 79篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 11篇 |
2018年 | 10篇 |
2017年 | 2篇 |
2016年 | 9篇 |
2015年 | 13篇 |
2014年 | 13篇 |
2013年 | 23篇 |
2012年 | 32篇 |
2011年 | 52篇 |
2010年 | 20篇 |
2009年 | 30篇 |
2008年 | 39篇 |
2007年 | 55篇 |
2006年 | 51篇 |
2005年 | 40篇 |
2004年 | 49篇 |
2003年 | 35篇 |
2002年 | 25篇 |
2001年 | 12篇 |
2000年 | 7篇 |
1999年 | 10篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 10篇 |
1993年 | 8篇 |
1992年 | 8篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1987年 | 10篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 12篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 7篇 |
1975年 | 5篇 |
1970年 | 2篇 |
1966年 | 2篇 |
1964年 | 2篇 |
排序方式: 共有708条查询结果,搜索用时 15 毫秒
91.
A Yoshimoto 《Radioisotopes》1988,37(9):517-520
About 15% of CPR-U did not correspond between two kinds of kits in the routine assay, which were produced by different pharmaceutical firms, and also it is realised that the effect of the preservative, storage condition and buffer dilutions can not be overlooked in quality control programmes. Based on these problems, following results are concluded; (1) Urine preservative: NaN3 is better than toluene. (2) Urine CPR was stable for added preservative at 4 degrees C for two weeks. (3) Diluents may effect the CPR-U results, if not kept in good condition. The role of the makers in supporting improved quality in clinical laboratory tests will be expected. 相似文献
92.
93.
D.C. polarograms of the Ni(II)-glycine complexes were measured with varying pH values at constant total glycine concentration (0.05 M) and conversely with varying total glycine concentration at constant pH values (3.5, 4.5, 7.5 and 9.5). The current—voltage curves obtained were analysed to determine the limiting currents, the transfer coefficients, and the half-wave potentials, by using the non-linear least squares method. From the dependence of the half-wave potentials on the free glycine concentration, the mechanism of the electrode processes was elucidated. It was shown that the first wave corresponded to the reduction of the Ni2+ aquo-complex, the second to the NiG+ complex, the third to the NiG2 complex and the fourth to the NiG?3 complex. The kinetic parameters for the four charge transfer processes were determined.The second and third waves were kinetic in character and the rate constants of the dissociation and association reactions between NiG+ and NiG2 and between NiG2 and NiG?3 were determined by analysing the dependence of the kinetic limiting currents on the free glycine concentration. 相似文献
94.
Ei-ichi Nishizawa Leenawaty Limantara Noriyuki Nanjou Hiroyoshi Nagae Tomisaburo Kakuno Yasushi Koyama 《Photochemistry and photobiology》1994,59(2):229-236
The frequency of BChl that was bound to the light-harvesting complex (LHC) of Rhodobacter sphaeroides R26 was found to be 1598 cm-1 , a result which suggests that a pair of BChl molecules form a dimer in the LHC in the T1 state. 相似文献
95.
A void network in a-Si films prepared by vacuum deposition was studied. A close relationship in annealing behavior has been observed between the changes in surface area of voids and in the ESR signal strength. 相似文献
96.
97.
Yoshimoto Abe Tetsushi Sekiguchi Takahisha Misono 《Journal of polymer science. Part A, Polymer chemistry》1984,22(3):761-767
The condensation of silicic acid butyl esters was investigated by gel permeation chromatographic (GPC) analysis. The results revealed that the condensation was greatly dependent on a degree of esterification of the esters. The ester with the lowest degree of esterification underwent condensation to form a highly polymerized ester. It was found that fibers could be drawn from the ester solution before gelation. 相似文献
98.
99.
Yamagiwa N Qin H Matsunaga S Shibasaki M 《Journal of the American Chemical Society》2005,127(38):13419-13427
The full details of a catalytic asymmetric aza-Michael reaction of methoxylamine promoted by rare earth-alkali metal heterobimetallic complexes are described, demonstrating the effectiveness of Lewis acid-Lewis acid cooperative catalysis. First, enones were used as substrates, and the 1,4-adducts were obtained in good yield (57-98%) and high ee (81-96%). Catalyst loading was successfully reduced to 0.3-3 mol % with enones. To broaden the substrate scope of the reaction to carboxylic acid derivatives, alpha,beta-unsaturated N-acylpyrroles were used as monodentate, carboxylic acid derivatives. With beta-alkyl-substituted N-acylpyrroles, the reaction proceeded smoothly and the products were obtained in high yield and good ee. Transformation of the 1,4-adducts from enones and alpha,beta-unsaturated N-acylpyrroles afforded corresponding chiral aziridines and beta-amino acids. Detailed mechanistic studies, including kinetics, NMR analysis, nonlinear effects, and rare earth metal effects, are also described. The Lewis acid-Lewis acid cooperative mechanism, including the substrate coordination mode, is discussed in detail. 相似文献
100.
Abe R Higashi M Sayama K Abe Y Sugihara H 《The journal of physical chemistry. B》2006,110(5):2219-2226
The photocatalytic activities of R3MO7 and R2Ti2O7 (R=Y, Gd, La; M=Nb, Ta) strongly depended on the crystal structure. Overall, photocatalytic water splitting into H2 and O2 proceeded over La3TaO7 and La3NbO7, which have an orthorhombic weberite structure, Y2Ti2O7 and Gd2Ti2O7, which have a cubic pyrochlore structure, and La2Ti2O7, which has a monoclinic perovskite structure. All of these materials are composed of a network of corner-shared octahedral units of metal cations (TaO6, NbO6, or TiO6); materials without such a network were inactive. The octahedral network certainly increased the mobility of electrons and holes, thereby enhancing photocatalytic activity. 相似文献