全文获取类型
收费全文 | 1173篇 |
免费 | 26篇 |
国内免费 | 4篇 |
专业分类
化学 | 755篇 |
晶体学 | 33篇 |
力学 | 38篇 |
数学 | 87篇 |
物理学 | 290篇 |
出版年
2023年 | 7篇 |
2022年 | 35篇 |
2021年 | 28篇 |
2020年 | 21篇 |
2019年 | 38篇 |
2018年 | 31篇 |
2017年 | 34篇 |
2016年 | 31篇 |
2015年 | 29篇 |
2014年 | 48篇 |
2013年 | 64篇 |
2012年 | 65篇 |
2011年 | 64篇 |
2010年 | 54篇 |
2009年 | 51篇 |
2008年 | 44篇 |
2007年 | 41篇 |
2006年 | 46篇 |
2005年 | 36篇 |
2004年 | 25篇 |
2003年 | 23篇 |
2002年 | 20篇 |
2001年 | 17篇 |
2000年 | 19篇 |
1999年 | 16篇 |
1998年 | 15篇 |
1997年 | 13篇 |
1996年 | 12篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 14篇 |
1992年 | 19篇 |
1991年 | 13篇 |
1990年 | 10篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 9篇 |
1985年 | 17篇 |
1984年 | 8篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 8篇 |
1977年 | 13篇 |
1976年 | 13篇 |
1975年 | 6篇 |
1974年 | 9篇 |
1967年 | 5篇 |
排序方式: 共有1203条查询结果,搜索用时 0 毫秒
71.
Riaz N Anis I Malik A Ahmed Z Aziz-ur-rehman Muhammad P Nawaz SA Choudhary MI 《Chemical & pharmaceutical bulletin》2003,51(3):252-254
Paeonins A and B, new monoterpene galactosides have been isolated from the chloroform-soluble fraction of the roots of Paeonia emodi and showed potent lipoxygenase inhibitory activity. The structures of 1 and 2 have been assigned on the basis of spectral analysis including one- and two-dimensional NMR techniques. 相似文献
72.
73.
Summary The chromatographic performance of newly developed dicyanobiphenyl polysiloxane stationary phases were evaluated and compared
with the performance of other polar stationary phases, including the previously reported monocyanobiphenyl polysiloxanes.
Due to the unique combination of polarizable biphenyl and polar cyano functionalities in the side chains of the flexible polysiloxane
backbone, and by virtue of their mild liquid crystalline properties, the new stationary phases provide excellent resolution
of a wide variety of analytes, both polar and nonpolar, in both GC and SFC. They can be easily coated and cross-linked in
open tubular columns, and the resultant columns demonstrate excellent efficiency and performance at temperatures up to 280–300°C.
The new stationary phases exhibit enhanced selectivities for various types of isomeric compounds. 相似文献
74.
E. Ben-Hur Z. Malik T. M. A. R. Dubbelman P. Margakon H. Ali J. E. van Lier 《Photochemistry and photobiology》1993,58(3):351-355
Abstract— Phthalocyanine (Pc) containing AI, Ga or Zn as central metal ligand and substituted with a varying number of sulfonic acid residues as well as additional benzene rings were synthesized and their photodynamic activity was assayed using photohemolysis of human erythrocytes as an endpoint. The Pc derivatives vaned > 300-fold in their photodynamic activity. Activity corrclated with binding of the dye to the cell, with the exception of some of the amphiphilic dyes where cell uptake was an order of magnitude higher than expected from the observed activity. Fluoride was shown to inhibit AIPcSn -induccd photohemolysis. This effect occurred also with other AlPc and GaPc derivatives, but the concentration of F required to slow photohemolysis by a factor of two (Ki ) varied between 4 μ M and 10 mM. Fluorescence spectral studies indicated complex formation between F− and the dye, which was stronger for AlPc than GaPc derivatives. Ultrastructural studies using scanning electron microscopy showed that the photosensitized cells were converted to spherocytes and that F− prevented this to a large extent. 相似文献
75.
Heterologous expression characteristics of Trichoderma viride endoglucanase V in the silkworm, Bombyx mori L 总被引:1,自引:0,他引:1
Li XH Wang MX Zhang P Hu JB Sun CG Liu XJ Zhou F Niu YS Malik FA Bhaskar R Yang HJ Miao YG 《Applied biochemistry and biotechnology》2011,165(2):728-736
Efficient degradation of cellulose needs a synergistic reaction of the cellulolytic enzymes, which include exoglucanases, endoglucanases, and β-1,4-glucosidase. In this study, we used an improved Bac-to-Bac/BmNPV baculovirus expression system, which lacks the virus-encoded chitinase cathepsin (v-cath) genes of Bombyx mori nucleopolyhedrovirus (BmNPV), to express the endoglucanase V (EG V) gene from Trichoderma viride in silkworm BmN cells and silkworm larvae, and analyzed the characteristics of the recombinant enzyme in silkworm larvae. The result showed that an around 36-kDa protein was visualized in BmN cells at 48 h after the second-generation recombinant mBacmid/BmNPV/EG V baculovirus infection. The crude enzyme extract from the recombinant baculoviruses-infected silkworms exhibited a significant maximum activity at the environmental condition of pH 5.0 and a temperature of 50 °C, and increased 39.86% and 37.76% compared with that from blank mBacmid/BmNPV baculovirus-infected silkworms and normal silkworms, respectively. It was stable at pH range from 5.0 to 10.0 and at temperature range from 40 to 60 °C. The availability of large quantities of EG V that the silkworm provides might greatly facilitate the future research and the potential application in industries. 相似文献
76.
Kabir-ud-Din Malik Abdul Rub Md. Sayem Alam 《Journal of Dispersion Science and Technology》2013,34(9):1182-1187
Herein we report the micellization and clouding behavior of promethazine hydrochloride (PMT) in absence and presence of NaCl/ureas. The critical micelle concentration (CMC) of PMT is measured by conductivity method and the values decrease with increasing the NaCl concentration. With increasing the temperature, the CMC first increases then decreases. At 25°C, the maximum CMC values were obtained (with or without NaCl). The thermodynamic parameters are evaluated which indicate more stability of the PMT solution in presence of NaCl. PMT shows phase separation also. The cloud point (CP) of PMT decreases with increase in pH due to deprotonation of the drug molecules. Ureas decreased the CP and the behavior is explained on the basis of removal of water from the head group region. 相似文献
77.
Offor P. O. Nwanya Assumpta C. Omah A. D. Daniel-Mkpume C. C. Maaza Malik Okorie B. A. Ezema Fabian I. 《Journal of Solid State Electrochemistry》2017,21(9):2687-2697
Journal of Solid State Electrochemistry - Zinc sulphide thin films were deposited by chemical spray pyrolysis technique. The films were deposited at substrate temperatures of 300, 350 and... 相似文献
78.
In the present investigations, the excess molar volumes, \( V_{ijk}^{\text{E}} \), excess isentropic compressibilities, \( \left( {\kappa_{S}^{\text{E}} } \right)_{ijk} \), and excess heat capacities, \( \left( {C_{p}^{\text{E}} } \right)_{ijk} \), for ternary 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (i) + 1-butyl-3-methylimidazolium tetrafluoroborate (j) + 1-ethyl-3-methylimidazolium tetrafluoroborate (k) mixture at (293.15, 298.15, 303.15 and 308.15) K and excess molar enthalpies, \( \left( {H^{\text{E}} } \right)_{ijk} \), of the same mixture at 298.15 K have been determined over entire composition range of x i and x j . Satisfactorily corrections for the excess properties \( V_{ijk}^{\text{E}} \), \( \left( {\kappa_{S}^{\text{E}} } \right)_{ijk} \), \( \left( {H^{\text{E}} } \right)_{ijk} \) and \( \left( {C_{p}^{\text{E}} } \right)_{ijk} \) have been obtained by fitting with the Redlich–Kister equation, and ternary adjustable parameters along with standard errors have also been estimated. The \( V_{ijk}^{\text{E}} \), \( \left( {\kappa_{S}^{\text{E}} } \right)_{ijk} \), \( \left( {H^{\text{E}} } \right)_{ijk} \) and \( \left( {C_{p}^{\text{E}} } \right)_{ijk} \) data have been further analyzed in terms of Graph Theory that deals with the topology of the molecules. It has also been observed that Graph Theory describes well \( V_{ijk}^{\text{E}} \), \( \left( {\kappa_{S}^{\text{E}} } \right)_{ijk} \), \( \left( {H^{\text{E}} } \right)_{ijk} \) and \( \left( {C_{p}^{\text{E}} } \right)_{ijk} \) values of the ternary mixture comprised of ionic liquids. 相似文献
79.
Mixtures of antidepressant amphiphilic drug imipramine hydrochloride and anionic surfactant: Micellar and thermodynamic investigation
下载免费PDF全文
![点击此处可从《Journal of Physical Organic Chemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Farah Khan Malik Abdul Rub Naved Azum Abdullah M. Asiri 《Journal of Physical Organic Chemistry》2018,31(6)
Aggregation as well as thermodynamic behavior of amphiphilic imipramine hydrochloride (IMH) drug (antidepressant) and anionic surfactant (sodium dodecyl sulfate [NaDS] as well as sodium dodecylbenzenesulfonate [NaDBS]) mixtures as a function of solution composition in aqueous solutions have been evaluated by conductometry method at different temperatures. Surfactant (NaDS and NaDBS) employed in the current study is anionic in nature. Various theoretical models such as Clint, Rubingh, Motomura, and Rodenas were employed to gain information regarding the type of interaction between the components in the solution mixtures. The value of micellar mole fraction evaluated by different utilized models is found to be more for IMH‐NaDBS mixtures in comparison with IMH‐NaDS mixtures, signifying that participation of NaDBS is more in mixed micelles as compared with NaDS. Owing to the different charge of employed drug and surfactant, which sources high synergistic results in the mixed system comparative to the possessions of their pure compounds, means here anionic surfactants were elected in favor of the quantitation of cationic drug. The value of interaction parameters (β) was also evaluated by employing the Rubingh's model. The values of Gibbs free energy (?G0m) for all systems attained to be negative in all studied systems showing that the systems are spontaneous in nature. 相似文献
80.
Inside Back Cover: In Situ Synthesis of Self‐Assembled Gold Nanoparticles on Glass or Silicon Substrates through Reactive Inkjet Printing (Angew. Chem. Int. Ed. 2/2014)
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)