全文获取类型
收费全文 | 8871篇 |
免费 | 1686篇 |
国内免费 | 926篇 |
专业分类
化学 | 5928篇 |
晶体学 | 87篇 |
力学 | 729篇 |
综合类 | 65篇 |
数学 | 1128篇 |
物理学 | 3546篇 |
出版年
2024年 | 38篇 |
2023年 | 183篇 |
2022年 | 306篇 |
2021年 | 321篇 |
2020年 | 347篇 |
2019年 | 322篇 |
2018年 | 294篇 |
2017年 | 292篇 |
2016年 | 433篇 |
2015年 | 424篇 |
2014年 | 467篇 |
2013年 | 646篇 |
2012年 | 755篇 |
2011年 | 827篇 |
2010年 | 552篇 |
2009年 | 530篇 |
2008年 | 612篇 |
2007年 | 476篇 |
2006年 | 517篇 |
2005年 | 375篇 |
2004年 | 314篇 |
2003年 | 252篇 |
2002年 | 234篇 |
2001年 | 201篇 |
2000年 | 190篇 |
1999年 | 190篇 |
1998年 | 181篇 |
1997年 | 173篇 |
1996年 | 169篇 |
1995年 | 137篇 |
1994年 | 121篇 |
1993年 | 112篇 |
1992年 | 91篇 |
1991年 | 69篇 |
1990年 | 75篇 |
1989年 | 61篇 |
1988年 | 44篇 |
1987年 | 34篇 |
1986年 | 34篇 |
1985年 | 22篇 |
1984年 | 18篇 |
1983年 | 14篇 |
1982年 | 15篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1975年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
151.
152.
Converse theorems for multidimensional Kantorovich operators 总被引:4,自引:0,他引:4
Ding -Xuan Zhou 《Analysis Mathematica》1993,19(1):85-100
L
p
[0, l]. . . - .
Supported by National Science Foundation, Zhejiang Provincial Science Foundation of China, and Alexander von Humboldt Foundation of Germany. 相似文献
Supported by National Science Foundation, Zhejiang Provincial Science Foundation of China, and Alexander von Humboldt Foundation of Germany. 相似文献
153.
We establish an explicit isomorphism between two realizations of the quantum affine algebra
given previously by Drinfeld and Reshetikhin-Semenov-Tian-Shansky. Our result can be considered as an affine version of the isomorphism between the Drinfield/Jimbo and the Faddeev-Reshetikhin-Takhtajan constructions of the quantum algebra
. 相似文献
154.
155.
Generalized elasticity theory of quasicrystals 总被引:1,自引:0,他引:1
156.
A series of 4-halophosphaisocoumarins were prepared with high regioselectivity in good to excellent yields under mild conditions by the reaction of 2-(1-alkynyl)phenylphosphonic acid diesters with I2 in CHCl3 or ICl in CH2Cl2, or by the reaction of 2-(1-alkynyl)phenylphosphonic acid monoesters with NBS or NCS in DMF. Whether the alkynylphosphonates could cyclize or not was affected by the substituents, reaction solvents and electrophiles. A rationale for this reaction is discussed. 相似文献
157.
葡萄糖氧化酶电极的制备 总被引:5,自引:0,他引:5
葡萄糖氧化酶电极的制备于秀娟,周定,郭京华(哈尔滨工业大学应用化学系哈尔滨150006)关键词葡萄糖氢化酶,酶电极,制备酶与电极的连接即酶膜的形成是制备酶电极的关键步骤之一,有许多种方式[1~9].葡萄糖氧化酶(GOD)电极是研究较早和报道较多的一类... 相似文献
158.
159.
With the development of transgenic crops, regulations to label the genetically modified organisms (GMOs) and their derived products have been issued in many countries. Polymerase chain reaction (PCR) methods are thought to be reliable and useful techniques for qualitative and quantitative detection of GMOs. These methods are generally needed to amplify the transgene and compare the amplified results with that of a corresponding reference gene to get the reliable results. Specific primers were developed for the rapeseed (Brassica napus), high-mobility-group protein I/Y(HMG-I/Y) single-copy gene and PCR cycling conditions suitable for the use of this sequence as an endogenous reference gene in both qualitative and quantitative PCR assays. Both methods were assayed with 15 different rapeseed varieties, and identical amplified products were obtained with all of them. No amplification was observed when templates were the DNA samples from the other species of Brassica genus or other species, such as broccoli, stem mustard, cauliflower, Chinese cabbage, cabbage, sprouts, Arabidopsis thaliana, carrot, tobacco, soybean, mung bean, tomato, pepper, eggplant, plum, wheat, maize, barley, rice, lupine, and sunflower. This system was specific for rapeseed. Limits of detection and quantitation in qualitative and quantitative PCR systems were about 13 pg DNA (about 10 haploid genomes) and about 1.3 pg DNA (about 1 haploid genome), respectively. To further test the feasibility of this HMG-I/Y gene as an endogenous reference gene, samples containing transgenic rapeseed GT73 with the inserted glyphosate oxidoreductase (GOX) gene were quantitated. These demonstrated that the endogenous PCR detection systems were applicable to the qualitative and quantitative detection of transgenic rapeseed. 相似文献
160.