全文获取类型
收费全文 | 220篇 |
免费 | 6篇 |
国内免费 | 6篇 |
专业分类
化学 | 161篇 |
晶体学 | 2篇 |
力学 | 7篇 |
数学 | 26篇 |
物理学 | 36篇 |
出版年
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 14篇 |
2012年 | 14篇 |
2011年 | 4篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 13篇 |
2007年 | 14篇 |
2006年 | 7篇 |
2005年 | 13篇 |
2004年 | 14篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1993年 | 8篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1965年 | 2篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1962年 | 1篇 |
1960年 | 1篇 |
1930年 | 2篇 |
排序方式: 共有232条查询结果,搜索用时 46 毫秒
81.
A novel [2] catenane containing a diphenylphosphino group on each ring was prepared. Synthesis of the new catenane involved the use of tetraamide rings to form an efficient pseudorotaxane intermediate. The catenane was found to be applicable as a ligand for metal-catalyzed reactions such as Suzuki-Miyaura coupling. 相似文献
82.
Fatty acids in 42 types of saponified vegetable and animal oils were analyzed by electrospray ionization mass spectrometry (ESI-MS) for the development of their rapid discrimination. The compositions were compared with those analyzed by gas chromatography-mass spectrometry (GC-MS), a more conventional method used in the discrimination of fats and oils. Fatty acids extracted with 2-propanol were-detected as deprotonated molecular ions ([M-H]-) in the ESI-MS spectra of the negative-ion mode. The composition obtained by ESI-MS corresponded to the data of the total ion chromatograms by GC-MS. The ESI-MS analysis discriminated the fats and oils within only one minute after starting the measurement. The detection limit for the analysis was approximately 10(-10) g as a sample amount analyzed for one minute. This result showed that the ESI-MS analysis discriminated the fats and oils much more rapidly and sensitively than the GC-MS analysis, which requires several tens of minutes and approximately 10(-9) g. Accordingly, the ESI-MS analysis was found to be suitable for a screening procedure for the discrimination of fats and oils. 相似文献
83.
84.
The title compound, which has the highest symmetry among tetrapyridylmethane isomers, has been synthesized from tris(4-pyridyl)methane and 4-chloropyridine. The silver(I) complex of the title compound forms a three-dimensional, non-interpenetrated diamondoid network in a crystal. 相似文献
85.
Kawase T Nishiyama Y Nakamura T Ebi T Matsumoto K Kurata H Oda M 《Angewandte Chemie (International ed. in English)》2007,46(7):1086-1088
86.
Isolation of a Hydrogen‐Bonded Complex Based on the Anthranol/Anthroxyl Pair: Formation of a Hydrogen‐Atom Self‐Exchange System 下载免费PDF全文
Dr. Yasukazu Hirao Tohru Saito Prof. Dr. Hiroyuki Kurata Prof. Dr. Takashi Kubo 《Angewandte Chemie (International ed. in English)》2015,54(8):2402-2405
A hydrogen‐bonded complex was successfully isolated as crystals from the anthranol/anthroxyl pair in the self‐exchange proton‐coupled electron transfer (PCET) reaction. The anthroxyl radical was stabilized by the introduction of a 9‐anthryl group at the carbon atom at the 10‐position. The hydrogen‐bonded complex with anthranol self‐assembled by π–π stacking to form a one‐dimensional chain in the crystal. The conformation around the hydrogen bond was similar to that of the theoretically predicted PCET activated complex of the phenol/phenoxyl pair. X‐ray crystal analyses revealed the self‐exchange of a hydrogen atom via the hydrogen bond, indicating the activation of the self‐exchange PCET reaction between anthranol and anthroxyl. Magnetic measurements revealed that magnetic ordering inside the one‐dimensional chain caused the inactivation of the self‐exchange reaction. 相似文献
87.
Isozaki K Ogata K Haga Y Sasano D Ogawa T Kurata H Nakamura M Naota T Takaya H 《Chemical communications (Cambridge, England)》2012,48(33):3936-3938
A new type of Pt-complex-bound amino acid was synthesized by condensation of a cyclometalated Pt complex with the side-chain residue of N- and C-alkylated glutamic acid. Self-assembly of the Pt-bound lipophilic amino acid afforded a supramolecular gel in organic solvents, which comprised fibrous lamellar aggregates that supported a highly oriented Pt array. 相似文献
88.
89.
Haruhisa Kikuchi Tomoko Hoshi Mizuki Sekiya Kazunori Ueda Hiroki Sato Shoichiro Kurata 《Tetrahedron》2009,65(2):469-7045
To date, entomopathogenic fungi have not been extensively examined by natural product chemists. In this study, we isolated novel pyrone diterpene-type compounds, metarhizins A (1) and B (2), from methanol extracts of entomopathogenic fungus, Metarhizium flavoviride. They showed potent and selective antiproliferative activity against both insect and human cancer cell lines. These results indicate that metarhizins A (1) and B (2) can be used as novel lead compounds for anti-cancer agents and probes for cell cycle regulation. To further investigate the structural requirements for this inhibitory activity, we synthesized many metarhizin derivatives and evaluated their antiproliferative activities. 相似文献
90.
Ekenechukwu C. Okafor K.D. Kunkuma A. Somarathne Akihiro Hayakawa Taku Kudo Osamu Kurata Norihiko Iki Hideaki Kobayashi 《Proceedings of the Combustion Institute》2019,37(4):4597-4606
Recent studies have demonstrated stable generation of power from pure ammonia combustion in a micro gas turbine (MGT) with a high combustion efficiency, thus overcoming some of the challenges that discouraged such applications of ammonia in the past. However, achievement of low NOx emission from ammonia combustors remains an important challenge. In this study, combustion techniques and combustor design for efficient combustion and low NOx emission from an ammonia MGT swirl combustor are proposed. The effects of fuel injection angle, combustor inlet temperature, equivalence ratio, and ambient pressure on flame stabilization and emissions were investigated in a laboratory high pressure combustion chamber. An FTIR gas analyser was employed in analysing the exhaust gases. Numerical modeling using OpenFOAM was done to better understand the dependence of NO emissions on the equivalence ratio. The result show that inclined fuel injection as opposed to vertical injection along the combustor central axis resulted to improved flame stability, and lower NH3 and NOx emissions. Numerical and experimental results showed that a control of the equivalence ratio upstream of the combustor is critical for low NOx emission in a rich-lean ammonia combustor. NO emission had a minimum value at an upstream equivalence ratio of 1.10 in the experiments. Furthermore, NO emission was found to decrease with ambient pressure, especially for premixed combustion. For the rich-lean combustion strategy employed in this study, lower NOx emission was recorded in premixed combustion than in non-premixed combustion indicating the importance of mixture uniformity for low NOx emission from ammonia combustion. A prototype liner developed to enhance the control and uniformity of the equivalence ratio upstream of the combustor further improved ammonia combustion. With the proposed liner design, NOx emission of 42?ppmv and ammonia combustion efficiency of 99.5% were achieved at 0.3?MPa for fuel input power of 31.44?kW. 相似文献