全文获取类型
收费全文 | 28771篇 |
免费 | 3486篇 |
国内免费 | 5519篇 |
专业分类
化学 | 18998篇 |
晶体学 | 688篇 |
力学 | 1632篇 |
综合类 | 828篇 |
数学 | 4238篇 |
物理学 | 11392篇 |
出版年
2023年 | 182篇 |
2022年 | 608篇 |
2021年 | 611篇 |
2020年 | 635篇 |
2019年 | 649篇 |
2018年 | 638篇 |
2017年 | 772篇 |
2016年 | 766篇 |
2015年 | 1022篇 |
2014年 | 1166篇 |
2013年 | 1838篇 |
2012年 | 1612篇 |
2011年 | 1875篇 |
2010年 | 1790篇 |
2009年 | 1840篇 |
2008年 | 2079篇 |
2007年 | 1991篇 |
2006年 | 1847篇 |
2005年 | 1795篇 |
2004年 | 1495篇 |
2003年 | 1300篇 |
2002年 | 1331篇 |
2001年 | 1153篇 |
2000年 | 1208篇 |
1999年 | 773篇 |
1998年 | 453篇 |
1997年 | 390篇 |
1996年 | 375篇 |
1995年 | 403篇 |
1994年 | 365篇 |
1993年 | 327篇 |
1992年 | 315篇 |
1991年 | 279篇 |
1990年 | 279篇 |
1989年 | 243篇 |
1988年 | 232篇 |
1987年 | 224篇 |
1986年 | 184篇 |
1985年 | 255篇 |
1984年 | 294篇 |
1983年 | 218篇 |
1982年 | 218篇 |
1981年 | 183篇 |
1980年 | 195篇 |
1979年 | 161篇 |
1978年 | 121篇 |
1977年 | 170篇 |
1976年 | 142篇 |
1975年 | 122篇 |
1973年 | 114篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
GAO Jing ZHOU Xiaohua CHEN Xun Chongqing University Chemical Engineering Department Chongqing China 《Chinese Journal of Reactive Polymers》2006,(2)
1. INTRODUCTION In the process of coking plant, about 30%~35% sulfur is transformed to H2S and some other sulfide, which form impurity in coal gas together with NH3 and HCN. Only 0.1% H2S containing in air can lead to die, so it is very important to carry on desulphurization and decyanation with coal gas [1~3]. Currently desulphurization and decyanation craft technique have Dry Oxidation Technology, Wet Oxidation Technology and Liquid Absorption Technology [2] three main kinds. The… 相似文献
2.
3.
Zuo LIU Zhen De WU 《数学学报(英文版)》2005,21(5):997-1000
Let κ be non-negative integer. The unoriented bordism classes, which can be represented as [RP(ξ^κ)] where ξ^κ is a k-plane bundle, form an ideal of the unoriented bordism ring MO.. A group of generators of this ideal expressed by a base of MO. and a necessary and sufficient condition for a bordism class to belong to this ideal are given. 相似文献
4.
In this paper we obtain a number of Maharam-type slice integral representations, with respect to scalar measures, for positive
projections in Dedekind complete vector lattices and f-algebras.
AMS Classification: 47B65, 46A40, 06F25 相似文献
5.
Michael De Castro 《Tetrahedron letters》2004,45(34):6501-6504
2-Deoxy-2-iodo-glycosylamides have been prepared from a variety of protected d-glucals by their reaction with N-iodosuccinimide and amides. Benzyl protected 2-iodoamides, when treated with sodium hydride and 15-crown-5, gave stable C1 N-linked 2-glycooxazolines as the major products. Silyl protected 2-iodoamides afforded the C1 O-linked 2-glycooxazolines; presumably by the rearrangement of unstable N-acylaziridine intermediates. 相似文献
6.
7.
8.
9.
The basic features of a chemical measurement 总被引:2,自引:0,他引:2
10.
ZHANG Zhi-bin LI Min SONG Hong FANG Yi Hua Hui CHEN Li-guo ZHOU Wei WANG Zheng-rong 《合成化学》2004,12(Z1)
Microcapsulation is a technology that enwrapped the solid or liquid or some gas matter with membrane materials to form microparticles(i.e.microcapsules). The materials of microcapsule is composed of naturnal polymers or modified naturnal polymers or synthesized polymers. The water-soluble core matter can only use oil-soluble wall materials, and vice versa.Synthesized methods of polymer microcapsulesSynthesized methods with monomers as raw materialsThis kind of methods include suspension polymerization, emulsion polymerization, dispersal polymerization, precipitation polymerization,suspension condensation polymerization, dispersal condensation polymerization, deposition condensation polymerization, interface condensation polymerization, and so on.Synthesized methods with polymers as raw materialsThese methods are suspension cross-linked polymerization, coacervation phase separation,extraction with solvent evaporation, polymer deposition, polymer chelation, polymer gel,solidification of melting polymer, tray-painted ways, fluidized bed ways, and so forth.Polymer materials to synthesize microcapsules2.1. Naturnal polymer materialsThe characteristics of this kind of materials are easy to form membrane, good stability and no toxicity. The polymer materials include lipids(liposome), amyloses, proteins, plant gels, waxes, etc.2.2. Modified polymer materialsThe characteristics of these materials are little toxicity, high viscidity(viscosity), soluble salt materials. But they cannot be used in water, acidic environment and high temperature environment for a long time. The materials include all kind of derivants of celluloses.2.3. Synthesized polymer materialsThe characteristics of the materials are easy to form membrane, good stability and adjustment of membrane properties. The synthesized polymer materials include degradable polymers(PLA, PGA,PLGA, PCL, PHB, PHV, PHA, PEG, PPG and the like) and indegradable polymers(PA, PMMA,PAM, PS, PVC, PB, PE, PU, PUA, PVA and otherwise).The applications of polymer microcapsules in cell technologyThe "artificial cell" is the biological active microcapsule used in biological and medical fields.The applications of cells (including transgenic cells, the same as artificial cells) technology include several aspects as follows:3.1. Microcapsulation of artificial red cell3.2. Microcapsule of artificial cell of biological enzyme3.3. Microcapsule of artificial cell of magnetic material3.4. Microcapsule of artificial cell of active carbon3.5. Microcapsule of active biological cell 相似文献