全文获取类型
收费全文 | 198篇 |
免费 | 6篇 |
专业分类
化学 | 135篇 |
晶体学 | 2篇 |
力学 | 1篇 |
数学 | 22篇 |
物理学 | 44篇 |
出版年
2023年 | 2篇 |
2020年 | 3篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 5篇 |
2013年 | 12篇 |
2012年 | 2篇 |
2011年 | 11篇 |
2010年 | 13篇 |
2009年 | 5篇 |
2008年 | 10篇 |
2007年 | 9篇 |
2006年 | 10篇 |
2005年 | 12篇 |
2004年 | 10篇 |
2003年 | 15篇 |
2002年 | 13篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1975年 | 3篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1970年 | 4篇 |
1967年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有204条查询结果,搜索用时 31 毫秒
91.
92.
Seiki Nhikawa Philippe Tondeur Lieven Vanhecke 《Annals of Global Analysis and Geometry》1992,10(3):291-304
Let F be a Riemannian foliation on a Riemannian manifold (M, g), with bundle-like metric g. Aside from the Laplacian △g associated to the metric g, there is another differential operator, the Jacobi operator J▽, which is a second order elliptic operator acting on sections of the normal bundle. Its spectrum is discrete as a consequence of the compactness of M. Hence one has two spectra, spec (M, g) = spectrum of △g (acting on functions), and spec (F, J▽) = spectrum of J▽. We discuss the following problem: Which geometric properties of a Riemannian foliation F on a Riemannian manifold (M, g) are determined by the two types of spectral invariants? 相似文献
93.
94.
Let X and Y be m × n matrices whose elements are in K, a real or complex field. We obtain necessary and sufficient conditions for the existence of a matrix A belonging to the convex hull of a certain subgroup of the general linear group GLn(K) such that X = YA, which unite and generalize several known results concerning majorization. 相似文献
95.
Nakanishi A Tamai M Kawasaki N Nakamura T Araki M Tanada S 《Journal of colloid and interface science》2002,255(1):59-63
The recycling of organic wastes has become very important and the development of technology for recycling organic wastes needs to sustain industrial development. In this study, techniques for producing carbonaceous materials from organic wastes are described and water adsorption is characterized. The organic wastes used are coffee grounds and oolong tea leaves carbonized at 673 to 1073 K. The iodine adsorption capacity of the carbonaceous materials increased with increased carbonization temperature. The amount of water adsorbed onto the carbonization materials produced from oolong tea leaves at 873 K for 2 h was the highest. The Freundlich constant 1/n and the differential heat of adsorption of the carbonaceous materials produced from oolong tea leaves were greater than that of the carbonaceous materials produced from coffee grounds. The ability to humidity control can be estimated by the difference between the amount of water adsorbed relative pressure 0.90 and that at relative pressure 0.55. The ability to humidity control was the greatest for the carbonaceous materials produced from the oolong tea leaves at 873 K for 2 h and did not depend upon the adsorption temperature. These results indicated that the carbonaceous materials produced from oolong tea leaves at 873 K for 2 h could have more humidity control. 相似文献
96.
Ishikawa T Mizuta T Hagiwara K Aikawa T Kudo T Saito S 《The Journal of organic chemistry》2003,68(9):3702-3705
Catalytic alkynylation of diverse ketones and aldehydes using nonmetallic benzyltrimethylammonium hydroxide or a basic resin of the hydroxide type in DMSO is described. Aliphatic or alicyclic carbonyl partners gave satisfactory results, whereas aromatic ones afforded products with low yields. When aromatic aldehydes were reacted with phenylacetylene, enones such as chalcone derivatives were obtained in place of ynols. These organobase-catalyzed systems provide a practical nonmetallic protocol for C[bond]C formation. 相似文献
97.
2‐(2‐Amino‐3,4,5,6‐tetrafluorophenyl)benzoxazole ( 2 ) absorbs in long wavelength band (λabsmax = 346 nm in methanol) and in the normal wavelength band (λabsmax = 285.5 nm), and emits blue fluorescence. The emission intensity is highly affected by the solvent polarity and is large in a polar solvent such as methanol. 2‐(2‐Pentafluorobenzamido‐3,4,5,6‐ tetrafluorophenyl)benzoxazole ( 5 ) emits green fluorescence along with the short wavelength emission around 380 nm and their relative intensity depends on the solvent polarity. Green fluorescence is enhanced in nonpolar solvents such as chloroform and toluene, resulting in the considerably large Stokes shift. 相似文献
98.
Synthesis of methyl 7-tricyclo[4.2.2.01,6]deca-2,4,7,9-tetraenecarboxylate which possesses a novel carbon framework, a Dewar benzene bridged at C-1 and C-4 with 1,3-butadienylene, and its chemical properties have been reported. 相似文献
99.
Takeshi Doi You Osada Atsushi MorishigeOkihito Tokunaga Teijiro Miyata Kouichi HirotaMichihiro Nakajima Mikihisa Komiya Kiyonori Miyajima Shigekazu Baba 《Radiation Physics and Chemistry》1993,42(4-6)
According to the basic research performed using a small size reactor at TRCRE of JAERI, the electron beam irradiation process was proved to be very effective for NOx, SO2 and HC removals from flue-gas of municipal waste incinerators. Based on this result, a pilot-plant was constructed for the demonstration of NOx, SO2 and HC removal performance using electron accelerator of maximum energy 0.95 MeV and maximum power 15kW.The pilot-plant was constructed at Matsudo City waste Disposal Center. The flue-gas of 1,000 Nm3/hr is guided from the waste incinerator flue-gas line of 30,000Nm3/hr to the pilot-plant to be processed by spraying Ca(OH)2 slurry or powder and irradiation with high-energy electron beam of the accelerator. NOx, SO2 and HC are removed simultaneously from the flue-gas by the enhanced reaction with Ca (OH)2 under irradiation.A brief explanation of the pilot-plant and preliminary results of the experiments are introduced in this paper. 相似文献
100.