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21.
XI Shang-Zhong 《结构化学》2001,20(4)
1 INTRODUCTIONAtrope alkaloids, which exist in eggplant plants, such as atrope and scopolamine, are used as a series of important drugs in medical science [1,2]. The typical character of atrope alkaloid is that these compounds contain the main skeleton of 8-azabicycle[3,2,1]octane , which results in the very complicated synthetic routine[3]. During our research for the reaction of 1,3,5,7-tetraphenyl-4- nitro-1,7-heptadione with low-valent titanium reagent, we easily synthesized the title … 相似文献
22.
Si WANG Pei Cheng ZHANG Ruo Yun CHEN De Quan YU* Institute of Materia Medica Chinese Academy of Medical Sciences 《中国化学快报》2001,(9)
Goniothalamus cheliensis Hu (Annonaceace) is a small tree or shrub in Yunnan Province, southwest of China. Acetogenins, styryllactones and alkaloids1-3 from the genus were reported in the previous literature and many of them showed strong cytotoxic activities against a number of human cancer cell lines4. The titled plant has been the subject of our investigation due to the impressive cytotoxicity of its organic extract against mouse lymphocytic leukemia cells in preliminary pharmacological s… 相似文献
23.
本文主要对IBr分子的飞秒含时光电子能谱进行了模拟计算.运用含时量子波包方法,对不同延迟时间的光电子能谱进行模拟计算与理论分析.应用波包和光诱导势理论,对光电子能谱共同的两峰系特征及多峰现象给予合理解释.光电子能谱的峰值随延迟时间的增加而递减现象,是由于波包在势能面上因分子解离发散,使整个波包在势能曲线上的振荡递减造成的.研究表明:波包的传播是一个能量减弱的过程;跃迁过程中不同电离通道之间的竞争,也对能谱存在一定的影响. 相似文献
24.
采用Gassian09程序包中的多种方法对OH,OCl,HOCl分子的基态结构进行优化计算,优选出QCISD/6-311G(2df),B3P86/6-31 1+G(2df)方法分别对OH(X2∏),OCl(X2∏)分子进行计算,得到平衡核间距ROH=0.09696nm,ROCl=0.1569 nm,谐振频率w(OH)=3745.37 cm-1,e(OCl)=892.046 cm-1,与实验结果非常符合.用Murrell-Sorbie势能函数对OH和OCl分子的扫描势能点进行拟合,其扫描点都与四参数Murrell-Sorbie函数拟合曲线符合得很好.优选出QCISD(T)/D95(df,pd)方法对HOCl分子进行计算,得到基态为X1A’,键长ROH=0.0966 nm,键角∠HOCl=102.3°,谐振频率w1(a1)=738.69 cm-1,w2(b2)=1260.25 cm-1,离解能De=2.24 eV.通过比较发现这些结果与实验值符合得很好,并优于文献报道的结果.随后计算出了力常数,在此基础上,推导出HOCl分子的多体展式势能函数.报道了HOCl分子对称伸缩振动势能图中在H+OCl→HOCl反应通道上有一鞍点,H原子需要越过1.74 eV的能垒才能生成HOCl的稳定结构,在Cl+OH→HOCl通道上不存在明显势垒,容易形成稳定的HOCl分子. 相似文献
25.
26.
1 INTRODUCTIONItwaswellknown thatelementsofthesecondary and higherrow are in generaldifficulty to form multiplebondsin which apπ hybridized stateisinvolved〔1〕.Thus,simple compounds containing multiple phosphorus carbon bonds,such as methyl dynephosphine( HC≡P) 〔2 - 3〕 and methylenephosphine( H2 C=PH〔4〕,are notstableat room temperature.Three methods to stabilize compounds containing double ormultiple bond involving phosphorusatom in the pπ hybridized state are often used.The f… 相似文献
27.
Xue Mei LUO Wei Jiang HE Yu ZHANG Zi Jian GUO Long Gen ZHU* State Key Laboratory of Coordination Chemistry Nanjing University Nanjing 《中国化学快报》2000,11(11)
Selectively chemical cleavage of peptides and proteins is one of the most important reactions in both chemical and biochemical processes. Over the past decade, the interaction of palladium(II) complexes with methionine, cysteine and histidine-containing peptides and proteins and the hydrolytic cleavage of the corresponding amide bond by Pd(II) complexes have been extensively studied1-13. However, reports concerning the directly selective hydrolysis of peptides and proteins with other simple … 相似文献
28.
Zhi NA Bei JIANG Hui YANG Zhong Wen LIN Han Dong SUN* Laboratory of Phytochemistry Kunming Institute of Botany Chinese Academy of Sciences Kunming Chemistry Deparment of the College of Life Science Chemistry Yunnan University K 《中国化学快报》2001,(8)
Isodon enanderianus (Hand. -Mazz.) H. W. Li, has been used in folk medicine as anti-inflammatory and detoxified agent1. The Isodon genus is known to be rich in ent-kaurane diterpenoids, a series of new ent-kaurane diterpenoids have been isolated from the dried leaves of I. enanderianus2-4. In order to find more biologically active substances, we have carefully investigated the chemical constituents of I. enanderianus collected in Shiping county of Yunnan province, and as a result, enanderi… 相似文献
29.
Mei Zhong JIN Li YANG Long Ming WU You Chen LIU Zhong Li LIU* National Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou 《中国化学快报》2001,(4)
Reduction of C=N double bonds has been recognized as an important reaction both in organic chemistry and bio-chemistry1. Hantzsch 1,4-dihydropyridine (HEH, one of NADH model compounds) has been reported as a reductive reagent for imines2. However, application of dihydropyridines as practical reducing reagents in organic synthesis is limited because of their instability3. Like NADH models, 2-phenyl-N, N-dimethylbenzimidazoline (PDMBI) is an efficient electron and hydrogen donor (Eox = 0… 相似文献
30.
Retention Behaviors of Uronic Acid-containing Polysaccharides and Neutral Polysaccharides in HPGPC 总被引:2,自引:0,他引:2
Cui Ping LIU Xing Feng BAO Ji Nian FANG* Shanghai Institute of Materia Medica Shanghai Institutes for Biological Sciences Chinese Academy of Sciences Shanghai 《中国化学快报》2001,(10)
The determination of molecular weights (Mw) of polysaccharides has served as an important process since the physical properties of the polysaccharides are closely related to their Mw and/or molecular weights distribution (MWD). For Mw and MWD determinations, high performance gel permeation chromatography (HPGPC) has gained wide acceptance as a preferred method due to its high sensitivity, speed and reproducibility. In chromatography, it is well known that the molecular weights are determ… 相似文献