全文获取类型
收费全文 | 3747篇 |
免费 | 714篇 |
国内免费 | 1392篇 |
专业分类
化学 | 2941篇 |
晶体学 | 135篇 |
力学 | 258篇 |
综合类 | 168篇 |
数学 | 417篇 |
物理学 | 1934篇 |
出版年
2024年 | 4篇 |
2023年 | 31篇 |
2022年 | 131篇 |
2021年 | 146篇 |
2020年 | 112篇 |
2019年 | 122篇 |
2018年 | 114篇 |
2017年 | 161篇 |
2016年 | 116篇 |
2015年 | 170篇 |
2014年 | 210篇 |
2013年 | 267篇 |
2012年 | 247篇 |
2011年 | 292篇 |
2010年 | 309篇 |
2009年 | 347篇 |
2008年 | 394篇 |
2007年 | 330篇 |
2006年 | 350篇 |
2005年 | 315篇 |
2004年 | 249篇 |
2003年 | 175篇 |
2002年 | 197篇 |
2001年 | 179篇 |
2000年 | 171篇 |
1999年 | 129篇 |
1998年 | 86篇 |
1997年 | 57篇 |
1996年 | 37篇 |
1995年 | 59篇 |
1994年 | 31篇 |
1993年 | 39篇 |
1992年 | 41篇 |
1991年 | 22篇 |
1990年 | 34篇 |
1989年 | 24篇 |
1988年 | 34篇 |
1987年 | 25篇 |
1986年 | 19篇 |
1985年 | 11篇 |
1984年 | 15篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 10篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1974年 | 3篇 |
1959年 | 3篇 |
排序方式: 共有5853条查询结果,搜索用时 15 毫秒
111.
Jue Xiao CAI Zheng Hong ZHOU Kang Ying LI Chi Hung YEUNG Chu Chi TANG* State Key Laboratory of Elemento-Organic Chemistry Institute of Elemento-Organic Chemistry Nankai University Tianjin Open Laboratory of Chirotechnology D 《中国化学快报》2002,13(7)
Optically active 1,1-binaphthalene-2, 2-diol has become a quite important chiral source in different fields of chirotechnology, especially in asymmetric synthesis1. Its synthesis and resolution has been extensively studied and various resolution methods have been reported2. Among the reported resolution methods, the following three, namely, via the formation of phosphoric acid derivatives3, boric acid derivatives4 and inclusion complexes5, are the most important. OHOH+_( )-1(-)-(S)-1(+)-(R)… 相似文献
112.
Qing LI Hui LI Bin SU Xiang Bao MENG Meng Shen CAI Zhong Jun LI* Department of Chemical Biology School of Pharmaceutical Sciences National Research Laboratory of Natural Biomimetic Drugs Peking University Beijing 《中国化学快报》2002,13(4):303-305
Our previous paper1,2reported the results of selective synthesis of mannose type glycosides and their dimers in our attempt to synthesize derivatives of N-acetyllacto- samine, which could have potential activity of anti-metastasis3. Further studies on the glycosylation of the accepters exploiting glycosyl nitrate instead of the acetate as donor showed interesting chemoselectivity between the two kinds of donor, namely, the glucose type and the mannose type. The reactivity difference of the t… 相似文献
113.
固氮酶及合成氨Fe催化剂中N2的络合位 总被引:1,自引:0,他引:1
用乙烯为探针研究了固氮酶中N2的键合位,结果表明,乙烯不能与N2在固氮酶体系中相竞争,提出N2在固氮酶中键合位很可能是蛋白键合FeMo-co笼内6Fe位的μρ(η^2,ε4)t 3Fe+1Mo位的μ4(η^3,ε)方式,而不是笼口2Fe位的μ2(η^2)方式,在合成氨Fe催化剂中N2的络事方式可能是μ6(η^3,ε3 )。 相似文献
114.
Two series of segmented copolymers with polysulfones, containing bisphenol A and phenol-phthalein units as hard segments respectively, were synthesized. Isocyanate-terminated polyoxy-propylene was used as soft segments for both series. 相似文献
115.
Yulu Yang Mingguang Wu Xingwang Zhu Hui Xu Si Ma Yongfeng Zhi Hong Xia Xiaoming Liu Jun Pan Jie-Yinn Tang Siang-Piao Chai Leonardo Palmisano Francesco Parrino Junli Liu Jianzhong Ma Ze-Lin Wang Ling Tan Yu-Fei Zhao Yu-Fei Song Pardeep Singh Pankaj Raizada Deli Jiang Di Li R. A. Geioushy Jizhen Ma Jintao Zhang Song Hu Rongjuan Feng Gang Liu Minghua Liu Zhenhua Li Mingfei Shao Neng Li Jiahe Peng Wee-Jun Ong Nikolay Kornienko Zhenyu Xing Xiujun Fan Jianmin Ma 《中国化学快报》1990,30(12):2065-2088
This roadmap demonstrates a series of two-dimensional nanomaterials, such as graphene, black phosphorus, oxides, layered double hydroxides, chalcogenides, bismuth-based layered compounds, MXenes, metal organic frameworks, covalent organic frameworks, and others, for environmental catalysis. 相似文献
116.
117.
ZHANG Jun SUN Xiao-min CAI Zheng-ting FENG Da-cheng 《高等学校化学研究》2006,22(5):663-664
In the stratosphere,CF3Cl(CFC13)can either photodecompose or react directly with atomic oxygen to generate ozone-depleting agents such as Cl and ClO in the gas phase[1—3].Since the1970s,attention has been focused on the effects of these compounds on the … 相似文献
118.
芳香二磺酸的配位化学研究化合物[Ni(cyclam)(1,5nds)]·1/3H_2O(1)和[Co(cyclam)(H_2O)_2](1,5nds)·2H_2O(2)的合成与结构(英文)
下载免费PDF全文
![点击此处可从《无机化学学报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
合成了两个二价的过渡金属磺酸化合物,并通过X-射线衍射单晶结构分析进行结构表征。化合物犤Ni(cyclam)(1,5nds)犦·1/3H2O(1)以P2(1)/c空间群结晶,晶胞参数为a=8.583(5),b=10.533(6),c=12.946(7)?,β=92.433(9)°。犤Ni(cyclam)犦2+与两个磺酸基团形成弱配位,从而构筑了一维的配聚物。犤Ni(cyclam)犦2+与磺酸基团之间的作用还通过O2S-O…H-N型氢键进一步被加强。化合物犤Co(cyclam)(H2O)2犦(1,5nds)·2H2O(2)以P1珔空间群结晶,晶胞参数为a=8.738(5),b=9.324(5),c=10.118(5)?,α=81.382(8),β=64.868(8),γ=62.999(8)°。在该化合物中,磺酸基团没有与Co2+形成配位键,而是以平衡离子的形式存在并与配离子形成氢键,构筑了有序的三维结构。 相似文献
119.
一维链状配位聚合物[Cu3(TFSSB)2·(H2O)4·4H2O]n的合成和晶体结构 总被引:4,自引:0,他引:4
The title complex [Cu3(TFSSB)2·(H2O)4·4H2O]n (TFSSB=taurine 3-formylsalicylic schiff base) was synthesized by TFSSB and copper(Ⅱ) acetate monohydrate in ethanol solution and the crystal structure was determined by X-ray diffraction method. The crystal belongs to monoclinic system, space group P21 / n,with cell parameters: a=0.927 9(6) nm, b=1.173 0(2) nm, c=1.471(2) nm, β=106.96(2)°, and V=1.531(2) nm3, Z=2, Dc=1.890 g·cm-3, μ=2.291 mm-1, F(000)=882, R1=0.025 9, wR2=0.065 9. The Cu1 is five-coordinate, the Cu2 is four-coordinate. CCDC: 253298. 相似文献
120.
A novel coordination ploymer [{Zn(3-SBA)(2,2′-bipy)(H2O)2}·H2O]n was synthesized by the hydrothermal reaction of 3-Na2SBA, ZnSO4·7H2O and 2,2′-bipy. The structure was characterized by elemental analysis, IR and single crystal X-ray diffraction. The title coordination ploymer crystallized in monoclinic with space group P21, a=0.803 42(18) nm, b=1.501 8(3) nm, c=0.821 13(19) nm, β=109.350(4)°. The coordination polymer has an infinite chain structure and its luminescent property has also been studied. CCDC: 282746. 相似文献