全文获取类型
收费全文 | 1053篇 |
免费 | 36篇 |
国内免费 | 7篇 |
专业分类
化学 | 769篇 |
晶体学 | 21篇 |
力学 | 21篇 |
数学 | 63篇 |
物理学 | 222篇 |
出版年
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 7篇 |
2020年 | 18篇 |
2019年 | 12篇 |
2018年 | 16篇 |
2017年 | 16篇 |
2016年 | 19篇 |
2015年 | 16篇 |
2014年 | 31篇 |
2013年 | 53篇 |
2012年 | 60篇 |
2011年 | 82篇 |
2010年 | 44篇 |
2009年 | 41篇 |
2008年 | 85篇 |
2007年 | 69篇 |
2006年 | 73篇 |
2005年 | 48篇 |
2004年 | 39篇 |
2003年 | 54篇 |
2002年 | 40篇 |
2001年 | 26篇 |
2000年 | 15篇 |
1999年 | 9篇 |
1998年 | 14篇 |
1997年 | 6篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 16篇 |
1993年 | 11篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 9篇 |
1985年 | 18篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 12篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1973年 | 3篇 |
排序方式: 共有1096条查询结果,搜索用时 15 毫秒
91.
Controlled production of monodisperse double emulsions by two-step droplet breakup in microfluidic devices 总被引:13,自引:0,他引:13
Okushima S Nisisako T Torii T Higuchi T 《Langmuir : the ACS journal of surfaces and colloids》2004,20(23):9905-9908
A microfluidic device having both hydrophobic and hydrophilic components is exploited for production of multiple-phase emulsions. For producing water-in-oil-in-water (W/O/W) dispersions, aqueous droplets ruptured at the upstream hydrophobic junction are enclosed within organic droplets formed at the downstream hydrophilic junction. Droplets produced at each junction could have narrow size distributions with coefficients of variation in diameter of less than 3%. Control of the flow conditions produces variations in internal/external droplet sizes and in the internal droplet number. Both W/O/W emulsions (with two types of internal droplets) and oil-in-water-in-oil emulsions were prepared by varying geometry and wettability in microchannels. 相似文献
92.
Ohno H Iwasaki H Eguchi T Tanaka T 《Chemical communications (Cambridge, England)》2004,(19):2228-2229
Intramolecular arylation of aryl radicals was mediated by SmI(2)/HMPA in the presence of i-PrOH to give spirocycles and/or reduced cine-cyclised products, while the reaction in the absence of i-PrOH gave the rearomatised fused rings. 相似文献
93.
We present the first study of the gluonic excitation in the three-quark (3Q) system in SU(3) lattice QCD with beta=5.8 and 16(3) x 32 at the quenched level. For the spatially fixed 3Q system, we measure the gluonic excited-state potential, which is responsible for the properties of hybrid baryons. The lowest gluonic-excitation energy in the 3Q system is found to be about 1 GeV in the hadronic scale. This large gluonic-excitation energy is expected to bring about the success of the simple quark model without gluonic modes. 相似文献
94.
Tobe M Isobe Y Tomizawa H Nagasaki T Aoki M Negishi T Hayashi H 《Chemical & pharmaceutical bulletin》2003,51(9):1109-1112
We investigated the chemical modifications of the nitroquinazoline derivative (1) through the replacement of the NH group at the C(4)-position with several N-alkyl groups to increase the lipophilicity at the C(4)-position. Among them, we found that the N-methyl analogue (5a) showed a 2-fold loss in the inhibitory activity toward tumor necrosis factor-alpha (TNF-alpha) production in vitro as compared with the NH analogue (1); however, 5a exhibited an oral inhibitory activity on TNF-alpha production with an ED50 value of 26 mg/kg, whereas 1 did not. Moreover, the oral bioavailability of 5a was higher than that of 1 (1, F=1%; 5a, F=21%), and the calculated ClogP value for 5a was higher than that for 1. These results suggest that the improved lipophilicity of 5a compared with that of 1 reflects its greater inhibitory activity on TNF-alpha production in vivo as well as oral bioavailability. 相似文献
95.
M. D. Volnyanskiĭ M. P. Trubitsyn Yakh’ya A. Kh. Obaĭdat 《Physics of the Solid State》2007,49(8):1453-1456
The temperature-frequency dependences of the permittivity of crystals of lithium heptagermanate Li2Ge7O15 doped with Cr3+ ions are investigated. A dielectric response to reorientation of the dipole moments of the chromium impurity centers is revealed. Anomalies of the permittivity are described within the model of a Debye relaxator. 相似文献
97.
98.
Toru Ishihara 《Geometriae Dedicata》1986,20(3):307-318
Teufel showed that total absolute curvature of a submanifold in a sphere or a hyperbolic space equals to the mean value of the number of critical points of level functions. This is an extension of the classical work of Chern and Lashof. In this paper we shall prove a similar result holds for the total absolute curvature of Kaehler manifold in a complex projective space. We shall also express the total curvature by the Euler numbers.The present research was supported by Grant in Aid for Scientific Research No. 5754005. 相似文献
99.
Jie Hao Kazuhisa Hiratani Naohiro Kameta Toru Oba 《Journal of inclusion phenomena and macrocyclic chemistry》2009,65(3-4):257-262
A novel tripodand having 3-hydroxy-2-naphthoeic amide groups was prepared by the reaction of 1,3,5-tris(aminomethyl)-2,4,6-trimethylbenzene with 3-allyloxy-2-naphthoeic acid chloride followed by thermal Claisen rearrangement. This tripodand can exhibit the anion binding ability in chloroform solution. In particular, it can bind with acetate, dihydrogen phosphate, and fluoride ions to form 1:1 complexes. 相似文献
100.
Philippe De Taxis Du Poet Shigeyuki Miyamoto Toru Murakami Jun Kimura Isao Karube 《Analytica chimica acta》1990
Direct electron transfer between active glucose oxidase (GOD) and a gold electrode was obtained when GOD was immobilized in poly(N-methylpyrrole) electrochemically prepared on the gold electrode. When electropolymerization was accomplished at 50 °C, after glucose addition, the cyclic voltammograms showed an increased oxidation peak at ca. ?0.45 V vs. Ag/AgCl. This potential corresponds to the oxidation potential for FADH2. Although the GOD becomes much less selective, a glucose-dependent current response is obtained. 相似文献