全文获取类型
收费全文 | 5244篇 |
免费 | 948篇 |
国内免费 | 745篇 |
专业分类
化学 | 4007篇 |
晶体学 | 69篇 |
力学 | 414篇 |
综合类 | 66篇 |
数学 | 549篇 |
物理学 | 1832篇 |
出版年
2024年 | 12篇 |
2023年 | 106篇 |
2022年 | 178篇 |
2021年 | 214篇 |
2020年 | 270篇 |
2019年 | 237篇 |
2018年 | 196篇 |
2017年 | 210篇 |
2016年 | 263篇 |
2015年 | 281篇 |
2014年 | 347篇 |
2013年 | 407篇 |
2012年 | 495篇 |
2011年 | 516篇 |
2010年 | 349篇 |
2009年 | 349篇 |
2008年 | 324篇 |
2007年 | 272篇 |
2006年 | 237篇 |
2005年 | 218篇 |
2004年 | 203篇 |
2003年 | 167篇 |
2002年 | 176篇 |
2001年 | 172篇 |
2000年 | 104篇 |
1999年 | 111篇 |
1998年 | 89篇 |
1997年 | 64篇 |
1996年 | 82篇 |
1995年 | 47篇 |
1994年 | 62篇 |
1993年 | 35篇 |
1992年 | 23篇 |
1991年 | 24篇 |
1990年 | 18篇 |
1989年 | 12篇 |
1988年 | 15篇 |
1987年 | 8篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有6937条查询结果,搜索用时 578 毫秒
101.
102.
103.
TaoJIANG BuXingHAN GuoYingZHAO ZhongHaoLI YanHongCHANG HaiXiangGAO JunChunLI 《中国化学快报》2004,15(3):296-299
The oxidation of styrene with molecular oxygen catalyzed by PdCl2 CuCl2 has been investigated in supercritical CO2 with a batch reactor. The oxidative system of styrene contains four components at the beginning and seven components during the reaction. The critical temperature, critical pressure, and critical density at different conversions are determined by using a high-pressure view cell. The effect of phase behavior on the conversion and selectivity were studied. Experimental results showed that the critical parameters of the reaction mixture at fixed initial molar ratio changed with the conversion of reactant. The conversion of styrene reached maximum near the critical density of the reaction mixture. Product selectivity also varied with density of reaction mixture and could be tuned to some degree. 相似文献
104.
Xing Hai Li Xin Ling Yang Xiao Mei Liang Zhen Peng Kai Yun Ling Fu Heng Chen Dao Quan Wang 《中国化学快报》2007,18(12):1476-1478
α-Chlorocycloalkanones(Ⅳ) were synthesized from cycloalkanones via potassiumα-oxocycloalkylsulfonates(Ⅱ).A two-step mechanism was proposed to explain the formation ofⅣfromⅡ. 相似文献
105.
YueMingLIU FengMeiZHANG HaiHongWU HaiJiaoZHANG JianGuoYANG XingTianSHU MingYuanHE 《中国化学快报》2004,15(10):1258-1260
A SAPO-11 silicoaluminophosphate molecular sieve with stable crystal structure was synthesized for the first time. After removing template by calcination, its crystal space group still retains Icm2 which the as-synthesized has. The catalyst deriving from the present SAPO-I 1 materials shows higher isomerization selectivity and higher paraffin hydroisomerization yield than those reported elsewhere. 相似文献
106.
Hydrogenolysis of Cp*W(NO)(CH2CMe3)2 at room temperature in cyclohexene results in the formation of the intermediate 16e organometallic complex, [Cp*W(NO)(eta2-cyclohexene)]. This intermediate leads to three parallel transformations of cyclohexene, namely (a) C-H activation of cyclohexene to form an eta3-cyclohexenyl hydrido complex, (b) combination of cyclohexene and H2 to form a cyclohexyl hydrido complex, and (c) coupling of two molecules of cyclohexene with concomitant loss of two hydrogen atoms to form a complex containing a novel eta1,eta3-(cyclohexyl)cyclohexenyl ligand. Single-crystal X-ray crystallographic analyses of products resulting from transformations (b) and (c) have been effected. 相似文献
107.
108.
[reaction: see text] Catalytic systems generated in situ from the chiral PNNP ligands with iridium or rhodium hydride complexes exhibited excellent catalytic activity and good enantioselectivity in the asymmetric transfer hydrogenation of aromatic ketones without added base. The best result was obtained in the IrH(CO)(PPh(3))(3)-ligand 2 catalytic system with up to 99% yield and 97% ee. 相似文献
109.
SyntheticinterestsinhighlyfunctionalizedacyclicandcyclicamineshavecontributedtothewealthofexPerimentalmethodologydeveloPedfortheadditionofcarbanionstothecarbon-nitrogendoublebondofimines.Generally,organometallicreagentsorilltermedi-atesareusedascarbanionsandadditionofallylicorganometallicspeciestothenieconshtutesavaluablemethodforthesynthesisofhomoallylamines.'Amongthese,allyLlithium,'-magnesium,'-zinc,'-boraneandboronate,'-silaneand-stannane'havebeenusedforallylationofdriines.Ontheotherhand,… 相似文献
110.
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