全文获取类型
收费全文 | 506篇 |
免费 | 8篇 |
国内免费 | 117篇 |
专业分类
化学 | 540篇 |
晶体学 | 3篇 |
综合类 | 3篇 |
物理学 | 85篇 |
出版年
2024年 | 1篇 |
2023年 | 20篇 |
2022年 | 5篇 |
2021年 | 7篇 |
2020年 | 15篇 |
2019年 | 9篇 |
2018年 | 9篇 |
2017年 | 13篇 |
2016年 | 13篇 |
2015年 | 6篇 |
2014年 | 13篇 |
2013年 | 25篇 |
2012年 | 28篇 |
2011年 | 43篇 |
2010年 | 26篇 |
2009年 | 38篇 |
2008年 | 36篇 |
2007年 | 44篇 |
2006年 | 33篇 |
2005年 | 30篇 |
2004年 | 35篇 |
2003年 | 11篇 |
2002年 | 12篇 |
2001年 | 10篇 |
2000年 | 14篇 |
1999年 | 16篇 |
1998年 | 12篇 |
1997年 | 15篇 |
1996年 | 15篇 |
1995年 | 7篇 |
1994年 | 13篇 |
1993年 | 12篇 |
1992年 | 13篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1986年 | 2篇 |
1979年 | 1篇 |
排序方式: 共有631条查询结果,搜索用时 15 毫秒
1.
Liying Zhang Chuanrui Zhao Yujiao Bai Qian Wang Pan Ma Xiaojie Ma Peihua Zhu 《Electroanalysis》2022,34(2):302-309
The design and exploration of efficient, stable and environmentally compatible organic emitters for an electrochemiluminescence (ECL) sensor is a promising topic. Herein, a novel environmentally-friendly luminophore, ZnBCBTP@MWCNTs, were fabricated via self-assembly of porphyrin molecules (ZnBCBTP) onto multi-walled carbon nanotubes (MWCNTs). The resulting luminophore ZnBCBTP@MWCNTs displayed not only the highly ECL property and but also the good accelerated electron mobility. Then, a label-free ECL biosensor based ZnBCBTP@MWCNTs was constructed for the ultrasensitive detection of uric acid. Excitingly, this proposed ECL biosensor performed a good linear relationship in the range of 0–300 μM with a low detection limit of 1.4 μM, thus offering another reliable and feasible sensing platform for clinical bioanalysis with good selectivity, stability, and repeatability. 相似文献
2.
G. Richard Geier III 《Tetrahedron》2004,60(50):11435-11444
To better understand the effects of diverse substituents on reactions leading to porphyrins, pyrrole+aldehyde condensations and related reactions of dipyrromethanes were examined. The course of pyrrole+aldehyde condensations was investigated by monitoring the yield of porphyrin (by UV-Vis spectroscopy), reaction of aldehyde (by TLC), and changes in the composition of oligomers (by laser desorption mass spectrometry). Reaction reversibility was examined via exchange experiments. Reversibility of reactions leading to porphyrin was further probed with studies of dipyrromethanes. The reaction course was found to depend on the nature of the substituent and the acid catalyst. Alkyl or electron-donating substituents displayed levels of reversibility (exchange/scrambling) on par or greater than that of the phenyl substituent, whereas electron-withdrawing or sterically bulky substituents exhibited little to no reversibility. The results obtained provide insight into the electronic and steric effects of different substituents and should facilitate the design of synthetic plans for preparing porphyrinic macrocycles. 相似文献
3.
Jun Hua YU Xue Song WANG Bao Wen ZHANG* Yi CAO Technical Institute of Physics Chemistry Chinese Academy of Sciences Beijing 《中国化学快报》2002,13(10)
Porphyrin derivatives attract much more interest in photodynamic therapy (PDT). Their importance as therapeutic drugs and targeting agents has been widely recognized1, and many of the efforts have been put towards crafting new porphyrin-based molecular entities to achieve enhanced tumor localization, better tissue penetration and increased singlet oxygen quantum yield2. The states of porphyrins in tissue models such as micelles, lipid bilayers are extensively investigated focusing more or l… 相似文献
4.
研究了阳离子表面活性剂十六烷基三甲基溴化铵 (CTAB)对四 ( 4 N 甲基吡啶 )卟啉 (H2 TMPyP)及其银配合物 (AgTMPyP)在Ag胶中的表面增强拉曼散射 (SERS)谱的影响 .SERS光谱表明 ,吸附于Ag胶粒的H2 TMPyP与衬底银原子结合形成AgTMPyP ,加入CTAB后 ,部分AgTMPyP表面络合物还原为H2 TMPyP .相似的去金属化反应也出现在AgTMPyP/Ag胶 /CTAB体系中 .CTAB的加入使SERS谱带强度明显增加 .AgTMPyP的去金属化被认为是由于CTAB的存在使Ag胶颗粒表面附近微环境发生改变 相似文献
5.
6.
乙酰丙酮稀土四苯基卟啉配合物的电化学研究 总被引:5,自引:0,他引:5
本文指出我国环境保护产业发展中存在的问题,论述了“入关“对我国环境保护产业的影响及应采取的经济和税收政策。 相似文献
7.
几种新型卟啉的合成及其光敏性质 总被引:3,自引:0,他引:3
合成了4种新的卟啉配体及其锌的配合物,并用红外光谱、紫外可见光谱、元素分析等手段对它们进行了表征。初步实验表明所合成的卟啉配体和金属卟啉均具有光敏性。 相似文献
8.
A new class of low melting liquid crystalline octaalkyloxyporphyrins have been synthesised. Their Zn(II)-complexes display an interesting ligation behaviour towards amines (of varying shapes and sizes), ascribed to the steric hindrance or hydrophobic pockets on both the faces of the porphryin as evidenced from the crystal structure of Zn(II)-octabutyloxyporphyrin. 相似文献
9.
Niu CG Gui XQ Zeng GM Guan AL Gao PF Qin PZ 《Analytical and bioanalytical chemistry》2005,383(2):349-357
A fluorescence ratiometric sensor for pH determination is described in this paper. The sensor incorporated the pH-sensitive
dye meso-5,10,15,20-tetra-(4-allyloxyphenyl)porphyrin (TAPP) as an indicator and a pH-insensitive dye N-(2-methacryloxyethyl)benzo[k,l]thioxanthene-3,4-dicarboximide (MBTD), a benzothioxanthene derivative, as a reference for fluorescence ratiometric measurement.
To prevent leakage of the dyes, both were photocopolymerized with acrylamide, hydroxyethyl methacrylate, and triethylene glycol
dimethacrylate on the silanized glass surface. The reproducibility and response time of the prepared sensor were sufficient.
Most common coexisting inorganic ions and organic compounds did not interfere with pH sensing. In the acidic pH range from
1.5 to 5.0 the fluorescence intensity ratio of the two dyes varied linearly as a function of pH. The sensing membrane was
found to have a lifetime of at least one month. The sensor was applied to the analysis of waste water and artificial samples. 相似文献
10.
P. Kuś 《Monatshefte für Chemie / Chemical Monthly》1997,128(8-9):911-917
Summary The synthesis and spectroscopic characterization of seven new tetraphenyl-porphyrins (1–7) derivatized with 12-crown-4, 14-crown-4, 15-crown-5, or 18-crown-6 ether units inortho orpara position of one of the phenyl rings is described.
In einem Phenylring mit Kronenethern monosubstituierte Tetraphenylporphyrine. Synthese und Charakterisierung
Zusammenfassung Die Synthese und die spektroskopische Charakterisierung sieben neuer Tetraphenylporphyrine (1–7), die mit 12-Krone-4, 14-Krone-4, 15-Krone-5 oder 18-Krone-6 in derortho-oderpara-Position eines Phenylrings substituiert sind, werden beschrieben.相似文献