全文获取类型
收费全文 | 652篇 |
免费 | 37篇 |
国内免费 | 1篇 |
专业分类
化学 | 443篇 |
晶体学 | 2篇 |
力学 | 9篇 |
数学 | 27篇 |
物理学 | 209篇 |
出版年
2024年 | 2篇 |
2023年 | 11篇 |
2022年 | 12篇 |
2021年 | 19篇 |
2020年 | 23篇 |
2019年 | 21篇 |
2018年 | 20篇 |
2017年 | 17篇 |
2016年 | 39篇 |
2015年 | 14篇 |
2014年 | 31篇 |
2013年 | 38篇 |
2012年 | 49篇 |
2011年 | 62篇 |
2010年 | 35篇 |
2009年 | 26篇 |
2008年 | 39篇 |
2007年 | 38篇 |
2006年 | 43篇 |
2005年 | 24篇 |
2004年 | 17篇 |
2003年 | 10篇 |
2002年 | 9篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 7篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有690条查询结果,搜索用时 15 毫秒
21.
Abstract: A simple method for the preparation of various substituted o-hydroxybenzaldehydes is reported. 相似文献
22.
Owen Zacarias Prof. Ana G. Petrovic Prof. Dr. Rinat Abzalimov Prof. Padmanava Pradhan Prof. Elise Champeil 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(57):14263-14272
Mitomycin C, (MC), an antitumor drug, is a DNA alkylating agent currently used in the clinics. Inert in its native form, MC is reduced to reactive mitosenes, which undergo nucleophilic attack by guanine or adenine bases in DNA to form monoadducts as well as interstrand crosslinks (ICLs). Although ICLs are considered the most cytotoxic lesions, the role of each individual adduct in the drug's cytotoxicity is still not fully understood. Synthetic routes have been developed to access modified oligonucleotides containing dG MC-monoadducts and dG-MC-dG ICL at a single position of their base sequences to investigate the biological effects of these adducts. However, until now, oligonucleotides containing monoadducts formed by MC at the adenine base had not been available, thus preventing the examination of the role played by these lesions in the toxicity of MC. Here, we present a route to access these substrates. Structural proof of the adducted oligonucleotides were provided by enzymatic digestion to nucleosides and high-resolution mass spectral analysis. Additionally, parent oligonucleotides containing a dG monoadduct and a dG-MC-dG ICL were also produced. The stability and physical properties of all substrates were compared via CD spectroscopy and UV melting temperature studies. Finally, virtual models were created to explore the conformational space and structural features of these MC-DNA complexes. 相似文献
23.
24.
25.
Pradhan Susanta Kumar Ambade Balram 《Journal of Radioanalytical and Nuclear Chemistry》2021,329(1):115-125
Journal of Radioanalytical and Nuclear Chemistry - Neutral complexes of thorium and lanthanides with 2,3-dihydroxynaphthalene and anionic complexes of uranium with the same chelating agent in... 相似文献
26.
Neeraj Pant N. Pradhan Mohammad Hassan Murad 《International Journal of Theoretical Physics》2014,53(11):3958-3969
We present a spherically symmetric solution of the general relativistic field equations in isotropic coordinates for perfect charged fluid, compatible with a super dense star modeling. The solution is well behaved for all the values of Schwarzschild parameter u lying in the range 0 < u < 0.1727 for the maximum value of charge parameter K = 0.08163. The maximum mass of the fluid distribution is calculated by using stellar surface density as ρ b = 4.6888×1014g cm?3. Corresponding to K = 0.08 and u max = 0.1732, the resulting well behaved solution has a maximum mass M = 0.9324M ⊙ and radius R = 8.00 and by assuming ρ b = 2×1014g cm?3 the solution results a stellar configuration with maximum mass M = 1.43M ⊙ and radius R b = 12.25 km. The maximum mass is found increasing with increasing K up to 0.08. The well behaved class of relativistic stellar models obtained in this work might has astrophysical significance in the study of internal structure of compact star such as neutron star or self-bound strange quark star like Her X-1. 相似文献
27.
In recent times, polyaniline (PANI), a conducting polymer, has been studied widely for environmental remediation application due to its controllable electric conductivity with high surface area, which makes it a suitable adsorbent material. But lower mechanical stability of PANI is considered to be a serious drawback for its large-scale industrial application. To improve the mechanical strength of PANI, in this study, hematite nanoparticles were impregnated onto PANI by oxidative polymerization method in order to fabricate a novel organometallic nanocomposite (hematite-PANI-NC). The hematite-PANI-NC was used as adsorbent for removal of methyl orange (MO) and eosin yellow (EY) dye from binary dye matrix under ultrasonic-assisted adsorption. Excellent MO and EY dye removal (more than 98%) was observed from binary matrix at a wide solution pH from 2.0 to 6.0, and under ultrasound wave the adsorption equilibrium was achieved within 15 min only. Both MO and EY dyes adsorption experimental data strictly followed Langmuir isotherm, and maximum monolayer adsorption capacity of 126.58 mg/g and 112.36 mg/g was observed for MO and EY dye, respectively. The uptake mechanism of MO and EY dyes onto hematite-PANI-NC is governed by electrostatic interaction, π-π bonding and hydrogen bonding between dye molecules and nanocomposite. Response surface methodology analysis reveals maximum MO and EY removal of 98.43% and 99.35% at optimum experimental conditions. This study implies that the hybrid organometallic material hematite-PANI-NC has high potential for quick and enhanced sono-assisted uptake of anionic dyes from water near neutral solution pH. 相似文献
28.
29.
30.
Adwait K. Pradhan Gadadhar Panda Nrusingha C. Patl Padma L. Nayak 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(2):501-512
The graft copolymerization of methyl methacrylate onto silk fibers initiated by the ferric chloride-eysteine redox system has been investigated in aqueous medium. The rate of grafting was calculated by varying the concentrations of monomer, initiator, acidity of the medium, cysteine, and temperature. The percentage of grafting increases with an increase of Fe3+ concentration up to 2,5 × 10?3 mol/L and thereafter it decreases. The graft yield increases steadily upon increasing the monomer concentration. The graft yield also increases with increasing cysteine concentration up to 0.5 × 10?3 mol/L and then decreases. The effect of the perchloric acid concentration, temperature, solvents, and certain neutral salts on graft yield has also been investigated and a suitable reaction scheme has been proposed. 相似文献