全文获取类型
收费全文 | 641篇 |
免费 | 11篇 |
国内免费 | 2篇 |
专业分类
化学 | 514篇 |
晶体学 | 7篇 |
力学 | 5篇 |
数学 | 10篇 |
物理学 | 118篇 |
出版年
2022年 | 4篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2016年 | 12篇 |
2015年 | 7篇 |
2014年 | 9篇 |
2013年 | 29篇 |
2012年 | 19篇 |
2011年 | 29篇 |
2010年 | 17篇 |
2009年 | 16篇 |
2008年 | 22篇 |
2007年 | 21篇 |
2006年 | 32篇 |
2005年 | 33篇 |
2004年 | 31篇 |
2003年 | 20篇 |
2002年 | 25篇 |
2001年 | 21篇 |
2000年 | 6篇 |
1999年 | 12篇 |
1998年 | 11篇 |
1997年 | 6篇 |
1996年 | 2篇 |
1995年 | 8篇 |
1994年 | 5篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 22篇 |
1984年 | 26篇 |
1983年 | 16篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 13篇 |
1979年 | 13篇 |
1978年 | 12篇 |
1977年 | 8篇 |
1976年 | 12篇 |
1975年 | 10篇 |
1974年 | 9篇 |
1973年 | 6篇 |
1972年 | 3篇 |
1969年 | 8篇 |
1968年 | 3篇 |
1961年 | 2篇 |
排序方式: 共有654条查询结果,搜索用时 15 毫秒
61.
Irie H Washizuka S Yoshino N Hashimoto K 《Chemical communications (Cambridge, England)》2003,(11):1298-1299
Nitrogen-substituted titanium dioxide thin films were found to undergo hydrophilic conversion under irradiation with visible light. The hydrophilicity was enhanced by increasing the degree of nitrogen substitution at oxygen sites. The water contact angle for the thin film with the greatest hydrophilicity, TiO1.9884N0.0116, changed from 20 degrees to 6 degrees following irradiation. 相似文献
62.
The effects of crosslinking on PVC are well known in regard to the improvement of mechanical properties, creep behavior, and softening temperature. Little is known, however, on the application of the PVC-crosslinking reaction, because most of crosslinked PVC tends to color easily at elevated temperatures. In this paper, a novel PVC-crosslinking reaction with 2-R-4,6-dithiol-s-triazine (I) has been presented to obtain insoluble products which hardly color on ageing. The reaction rate and induction period of the crosslinking reaction with I are made controllable by selecting the basicity of the substituent R of I as well as that of an acid acceptor in the blends. The utility of I as stabilizer as well as a crosslinking agent is also emphasized. 相似文献
63.
64.
The 7-endo Friedel-Crafts cyclization of arylpropyl vinyloxiranes was found to proceed regio- and stereoselectively to afford polyfunctional seven-membered carbocycles in excellent yields. 相似文献
65.
66.
Optical biosensor arrays for rapidly determining the glucose concentrations in a large number of beverage and blood samples were developed by immobilizing glucose oxidase (GOD) on oxygen sensor layer. Glucose oxidase was first encapsulated in silica based gels through sol-gel approach and then immobilized on 96-well microarrays integrated with oxygen sensing film at the bottom. The oxygen sensing film was made of an organically modified silica film (ORMOSIL) doped with tris(4,7-diphenyl-1,10-phenanthroline) ruthenium dichloride (Ru(dpp)3Cl2). The oxidation reaction of glucose by glucose oxidase could be monitored through fluorescence intensity enhancement due to the oxygen consumption in the reaction. The luminescence changing rate evaluated by the dynamic transient method (DTM) was correlated with the glucose concentration with the wide linear range from 0.1 to 5.0 mM (Y = 13.28X − 0.128, R = 0.9968) and low detection limit (0.06 mM). The effects of pH and coexisting ions were systemically studied. The results showed that the optical biosensor arrays worked under a wide range of pH value, and normal interfering species such as Na+, K+, Cl−, PO43−, and ascorbic acid did not cause apparent interference on the measurement. The activity of glucose oxidase was mostly retained even after 2-month storage, indicating their long-term stability. 相似文献
67.
Abstract
The crystal structure of the 2:1 co-crystal of 1,2,5-thiadiazole-3,4-dicarboxylic acid and 4,4′-bipyridine, (C4H2N2O4S)2·C10H8N2, has been determined by X-ray diffraction at the monoclinic space group C2/c with cell parameters of a = 21.388(7) ?, b = 6.735(2) ?, c = 14.877(5) ?, β = 110.431(3)°, and Z = 4. There are one molecule of thiadiazole and a half molecule of bipyridine in the asymmetric unit. The dihedral angle between the pyridine ring planes is 40.5(3)°. Two intramolecular O–H···N [2.730(7) ?] and O–H···O [2.433(6) ?] hydrogen bonds are observed in the thiadiazole molecule. In the crystal structure, the molecules form a unique two-dimensional ladder-type network linked by intermolecular O–H···N [2.704(4) ?] hydrogen bonds and S···O [3.100(5) ?] heteroatom interactions. 相似文献68.
Yoshiro Kaneko Dr. Kazuya Fujisaki Tsuyoshi Kyutoku Hidemitsu Furukawa Dr. Jun‐ichi Kadokawa Prof. 《化学:亚洲杂志》2010,5(7):1627-1633
In this paper, we describe the preparation of hydrogels through the formation of an inclusion complex of amylose in a vine‐twining polymerization. This is achieved by the phosphorylase‐catalyzed polymerization of α‐D ‐glucose 1‐phosphate from maltoheptaose primer, in the presence of a water‐soluble copolymer having hydrophobic graft‐chains (poly(acrylic acid sodium salt‐graft‐δ‐valerolactone)). The mixture turns into a gel during the polymerization process. Evaluation of the hydrogels is conducted by shear‐viscosity measurements of the products. For the hydrogels with relatively high viscosities, fast relaxation modes of the cooperative diffusions are observed by scanning microscopic light scattering measurements, which indicate the nanometer‐size network structures of the hydrogels. In addition, we found that the enzymatic disruption and reproduction of the hydrogels are achieved by the combination of the amylase‐catalyzed hydrolysis of the amylose component and the formation of amylose by the phosphorylase‐catalyzed polymerization. 相似文献
69.
A method is proposed for obtaining the spectrum for noise that causes the phase decoherence of a qubit directly from experimentally available data. The method is based on a simple relationship between the spectrum and the coherence time of the qubit in the presence of a π pulse sequence. The relationship is found to hold for every system of a qubit interacting with the classical-noise, bosonic, and spin baths. 相似文献
70.
Theoretical Analysis of Super-Resolution Optical Disk Mastering Using a Photoreactive Dye Mask Layer
The super-resolution mastering of read-only optical disks using a photoreactive bleachable dye mask layer was theoretically analyzed. Equations have been derived which describe the photoreactions of the resist layer and mask layer. A numerical simulation based on these equations showed that the transmittance of the mask directly affects the quality of the formed pit shape. A high-quality pit shape is obtained by using a low transmittance mask. 相似文献