全文获取类型
收费全文 | 1506篇 |
免费 | 36篇 |
国内免费 | 2篇 |
专业分类
化学 | 943篇 |
晶体学 | 14篇 |
力学 | 13篇 |
数学 | 37篇 |
物理学 | 537篇 |
出版年
2021年 | 11篇 |
2020年 | 19篇 |
2019年 | 15篇 |
2018年 | 14篇 |
2017年 | 11篇 |
2016年 | 20篇 |
2015年 | 26篇 |
2014年 | 18篇 |
2013年 | 63篇 |
2012年 | 63篇 |
2011年 | 71篇 |
2010年 | 42篇 |
2009年 | 35篇 |
2008年 | 76篇 |
2007年 | 103篇 |
2006年 | 81篇 |
2005年 | 88篇 |
2004年 | 79篇 |
2003年 | 64篇 |
2002年 | 69篇 |
2001年 | 49篇 |
2000年 | 29篇 |
1999年 | 12篇 |
1998年 | 13篇 |
1997年 | 12篇 |
1996年 | 24篇 |
1995年 | 13篇 |
1994年 | 21篇 |
1993年 | 16篇 |
1992年 | 19篇 |
1991年 | 19篇 |
1990年 | 16篇 |
1989年 | 17篇 |
1988年 | 18篇 |
1986年 | 15篇 |
1985年 | 28篇 |
1984年 | 26篇 |
1983年 | 17篇 |
1982年 | 12篇 |
1981年 | 20篇 |
1980年 | 18篇 |
1979年 | 26篇 |
1978年 | 22篇 |
1977年 | 23篇 |
1976年 | 15篇 |
1975年 | 8篇 |
1973年 | 10篇 |
1972年 | 7篇 |
1969年 | 7篇 |
1965年 | 7篇 |
排序方式: 共有1544条查询结果,搜索用时 15 毫秒
991.
Hayashi Y Urushima T Sakamoto D Torii K Ishikawa H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(42):11715-11718
992.
993.
Shingo Ishikawa Reuben Hudson Mitra Masnadi Mary Bateman Annie Castonguay Nadi Braidy Audrey Moores Chao-Jun Li 《Tetrahedron》2014
Simple bare copper-plated iron nanoparticles catalyzed the cyclopropanation of diazoesters with styrene derivatives. The reaction proceeded smoothly and provided the desired products in moderate to good yields, with selectivity for the trans isomer in neat conditions. The reaction scope was explored and di or tri-substituted cyclopropanes were synthesized. The catalysts could be magnetically separated and reusable up to five times. It was also characterized by TEM, XPS, and ICP-MS. A gram-scale reaction was performed with a yield of 72%. 相似文献
994.
Thais Graziela Donegá França Fernanda Chiuso-Minicucci Sofia Fernanda Gonçalves Zorzella-Pezavento Larissa Lumi Watanabe Ishikawa Larissa Camargo da Rosa Priscila Maria Colavite Camila Marques Maura Rosane Valério Ikoma Maria de Lourdes Ribeiro de Souza da Cunha Alexandrina Sartori 《BMC neuroscience》2014,15(1):1-11
Background
Bacterial superantigens are potent T cell activators that can activate T cells with specificity for antigens of the central nervous system (CNS). In this study, we compared the effect of two S. aureus strains on experimental autoimmune encephalomyelitis (EAE) development. C57BL/6 female mice were infected with S. aureus ATCC 51650, which produces toxic shock syndrome toxin 1 (TSST-1+) or S. aureus ATCC 43300, which does not produce toxins (TOX-). Three days later, the animals were subjected to EAE induction by immunization with myelin oligodendrocyte glycoprotein (MOG). The weight variation, disease incidence and clinical score were recorded daily. Cytokines and Foxp3+ regulatory T cells in the brain were evaluated during the acute disease phase. Cytokines and Foxp3+ regulatory T cells in the spleen and histopathological analysis of the CNS were assessed during the chronic stage.Results
Previous infection with both strains similarly decreased the clinical score; however, only the TSST-1+ strain clearly diminished inflammation in the CNS. The infections also modulated cytokine production in the spleen and CNS. Reduced production of IL-5 and IL-10 was detected in MOG-stimulated spleen cultures in the TOX- and TSST-1+ infected groups, respectively. In S. aureus stimulated cultures, there was an increased production of IFN-γ and IL-10 in both infected groups and an increased level of IL-5 in the TSST-1+ group. CNS infiltrating cell cultures from previously infected mice produced less IL-17 in response to MOG and more IFN-γ in response to S. aureus stimulation.Conclusions
These results indicated that both strains attenuated clinical EAE manifestations, but only TSST-1 clearly decreased CNS inflammation. 相似文献995.
Zhipeng Wang Mohd Zamri Mohd Yusop Takehiko Hihara Akari Hayashi Yasuhiko Hayashi Masaki Tanemura 《Applied Surface Science》2010,256(21):6371-3173
The irradiation of graphite surfaces with a simultaneous Fe supply have resulted into the development of various types of carbon nanocomposites. Their morphologies - diameter, density, length and apex angle strongly depend on the ratios of Fe deposition rate (DFe) to ion sputtering rate (Sion). By optimizing the ratio of DFe/Sion (2.40%), the denser and well-aligned Fe-carbon nanocomposite fibers (Fe-CNFs) could be obtained, whose average length and diameter were 0.95 μm and 17 nm, respectively. As confirmed by energy-dispersive X-ray analysis, the Fe-CNFs with amorphous-like or fine-polycrystalline phase were surely composed of carbon and Fe. Two types of growth models have been employed to explain the formation of metal-carbon nanocomposites. 相似文献
996.
Kazuhiko Kandori Aya Fujiwara Akemi Yasukawa Tatsuo Ishikawa 《Colloids and surfaces. A, Physicochemical and engineering aspects》1999,150(1-3):161-170
Grafting of oleylphosphate (OP) molecules to the surface of calcium hydroxyapatite particles (HAP) was carried out by a coprecipitation method with a Ca(OH)2–H3PO4 system in the presence of disodium oleylphosphate (DSOP). All the particles exhibited a single-crystal nature with rod-like shape and were elongated along c-axis from 36 to 122 nm in particle length with an increase in the concentration of DSOP. It was suggested that 084% of the phosphate ions exposed on the ac or bc faces of the HAP particles are exchanged with phosphate ions of DSOP molecules directing oleyl groups outward. The hydrophobicity of OP-grafted HAP particles was enhanced with an increase in the DSOP concentration. This high surface hydrophobicity was further confirmed by water adsorption experiments. The materials with the surface oleyl groups adsorbed much less water than the HAP particles produced without DSOP. 相似文献
997.
998.
Marco Colella Arianna Tota Dr. Yusuke Takahashi Ryosuke Higuma Susumu Ishikawa Prof. Dr. Leonardo Degennaro Prof. Dr. Renzo Luisi Prof. Dr. Aiichiro Nagaki 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(27):11016-11020
The external quenching method based on flow microreactors allows the generation and use of short-lived fluoro-substituted methyllithium reagents, such as fluoromethyllithium, fluoroiodomethyllithium, and fluoroiodostannylmethyllithium. Highly chemoselective reactions have been developed, opening new opportunities in the synthesis of fluorinated molecules using fluorinated organometallics. 相似文献
999.
T. Kinoshita H. Yamazaki H. Fukasawa K. Hirota T. Ishikawa J. Kasagi A. Kato T. Katsuyama K. Kino F. Miyahara T. Nakabayashi K. Nawa K. Okamura Y. Saitoh K. Satou M. Sengoku H. Shimizu K. Suzuki S. Suzuki T. Terasawa H. Kanda K. Maeda T. Takahashi Y. Aruga T. Fujinoya A. Iijima M. Itaya Y. Ito T. Iwata H. Kato T. Kawamura T. Michigami M. Moriya T. Sasaki Y. Tajima S. Takita T. Noma M. Yamamoto H.Y. Yoshida Y. Yoshida O. Konno T. Maruyama T. Yorita 《Physics letters. [Part B]》2006
1000.
F.Miyahara H.Fukasawa R.Hashimoto T.Ishikawa M.Itoh T.Iwata H.Kanda J.Kasagi H.Kato T.Kinoshita K.Maeda M.Matsuzawa T.Michigami K.Motiduki K.Murakami T.Nakabayashi K.Nawa T.Nomura K.Okamura H.Okamura H.Okuyama Y.Onodera Y.Saito T.Sasaki H.Shirnizu T.Shishido S.Suzuki K.Suzuki Y.Tajima S.Takita T.Takahashi H.Ueno S.Yamaguchi H.Yamazaki H.Y.Yoshida 《原子核物理评论》2009,26(Z1)
Differential and total cross sections of the γp→π~0 p and the γp→π~0 pn reaction were measured for photon energies between 640 and 1 150 MeV.The data have been compared with SAID and MAID model calculations.π~0 photoproduction on the deuteron shows a strong suppression of the 2nd resonance which is clearly seen in the γp→π~0 p reaction. 相似文献