全文获取类型
收费全文 | 9099篇 |
免费 | 1854篇 |
国内免费 | 2135篇 |
专业分类
化学 | 6656篇 |
晶体学 | 264篇 |
力学 | 797篇 |
综合类 | 289篇 |
数学 | 1098篇 |
物理学 | 3984篇 |
出版年
2024年 | 35篇 |
2023年 | 147篇 |
2022年 | 349篇 |
2021年 | 372篇 |
2020年 | 412篇 |
2019年 | 353篇 |
2018年 | 349篇 |
2017年 | 413篇 |
2016年 | 406篇 |
2015年 | 502篇 |
2014年 | 612篇 |
2013年 | 723篇 |
2012年 | 793篇 |
2011年 | 806篇 |
2010年 | 645篇 |
2009年 | 717篇 |
2008年 | 701篇 |
2007年 | 596篇 |
2006年 | 566篇 |
2005年 | 532篇 |
2004年 | 440篇 |
2003年 | 333篇 |
2002年 | 347篇 |
2001年 | 384篇 |
2000年 | 307篇 |
1999年 | 220篇 |
1998年 | 164篇 |
1997年 | 107篇 |
1996年 | 117篇 |
1995年 | 86篇 |
1994年 | 97篇 |
1993年 | 91篇 |
1992年 | 66篇 |
1991年 | 51篇 |
1990年 | 39篇 |
1989年 | 33篇 |
1988年 | 38篇 |
1987年 | 19篇 |
1986年 | 24篇 |
1985年 | 20篇 |
1984年 | 14篇 |
1983年 | 14篇 |
1982年 | 12篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1965年 | 2篇 |
1964年 | 2篇 |
1962年 | 2篇 |
1960年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
A novel protocol for assembling polycyclic ethers was developed and successfully applied to the synthesis of the EFGH ring system of ciguatoxin CTX3C. A key transformation involves construction of an O,S-acetal through coupling of alpha-chlorosulfide and a secondary alcohol under mild conditions. The method is highly applicable to use with sensitive substrates and will enable the synthesis of various natural and artificial polycyclic ethers. [reaction: see text] 相似文献
102.
Jing CHAO Xing Yuan ZHANG Jia Bing DAI Zhen GE Lin Lin FENG 《中国化学快报》2006,17(8):1121-1124
Aqueous acrylic-polyurethane dispersions have become one of the major types of materials used in coating, paint and adhesive industries, because of excellent properties and environmental advantages1-5. However, some properties for cured film such as water… 相似文献
103.
Synthesis of Molecularly Imprinted Polymer Particles by Suspension Polymerization in Silicon Oil 总被引:1,自引:0,他引:1
Xiao Bing WANG Zhao Hui ZHENG Xiao Bin DING Xu CHENG Xin Hua HU Yu Xing PENG 《中国化学快报》2006,17(9):1243-1246
Molecular imprinting is a method to prepare polymers with recognition site of desired and predetermined selectivity1. Molecularly imprinted polymers (MIP) are prepared by copolymerizing functional and cross-linking monomers in the presence of a molecular … 相似文献
104.
Xing L Ziener U Sutherland TC Cuccia LA 《Chemical communications (Cambridge, England)》2005,(46):5751-5753
This work describes a high-yielding, one-step synthesis of pyrizadine and naphthyridine containing macrocycles directed by intramolecular H-bonding. 相似文献
105.
Li Qiu WANG Xiao Jun PENG* Rong ZHANG Guo Quan XU Jing Nan CUI State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian 《中国化学快报》2003,(1)
Indocyanine dyes as fluorescent labeling reagents have been used in bioanalysis1,2. Arylsulfonate indocyanine dyes 1d and 1e developed by Waggoner A. S. et al.3,4 have excellent fluorescent properties combined with good aqueous solubility, are a new generation of fluorescent label compounds for proteins, oligonucleotides and other compounds containing hydroxyl, mercaptol or primary amine groups5. However, photostability of these dyes has been a problem. Z. G. YAO et al.6 reported that p… 相似文献
106.
107.
CP violation in partial-decay-rate asymmetries are examined for some two-body baryonic decays of \(B_d^0 - \bar B_d^0 \) system. We discuss two feasible experimental circumstances: the symmetrice + e ? collisions (i) on theZ 0 resonance to produce incoherent \(B_d^0 \bar B_d^0 \) states, and (ii) just above the ?(4S) resonance to produceC=even \(B_d^0 \bar B_d^0 \) states. Using the quark-diagram scheme, we estimate the branching ratios of those decays, and the numbers ofb \(\bar b\) pairs needed for testing theCP-violating effects for 3σ signature. We find that the promising channels may beB d 0 , \(\bar B_d^0 \to p\bar p\) , \(\Delta ^ + \bar \Delta ^ - \) , \(p\bar \Delta ^ - \) , \(\Delta ^ + \bar p\) , \(n\bar n\) , \(\Delta ^0 \bar \Delta ^0 \) , \(n\bar \Delta ^0 \) , \(\Delta ^0 \bar n\) , \(\Sigma _c^ + \bar \Sigma _c^ - \) , \(\Lambda _c^ + \bar \Lambda _c^ - \) , \(\Sigma _c^ + \bar \Lambda _c^ - \) , \(\Lambda _c^ + \bar \Sigma _c^ - \) , \(\Sigma _c^0 \bar \Sigma _c^0 \) , \(\Xi _c^0 \bar \Xi _c^0 \) , which should be interesting for experimental observation. 相似文献
108.
109.
110.
Xing Zhou Hong 《Applied Mathematics and Optimization》1982,8(1):275-285
The one-dimensional semilinear heat equation
is considered. It is shown that if the nonlinear functionF(y) is uniformly bounded then the system is approximately controllable for every given terminal timeT>0 under some ordinary condition onb. The results may be extended to the general one-dimensional semilinear heat equation with one-dimensional control or to a boundary control heat system with semilinear boundary condition. 相似文献