全文获取类型
收费全文 | 477篇 |
免费 | 9篇 |
国内免费 | 1篇 |
专业分类
化学 | 331篇 |
晶体学 | 6篇 |
力学 | 7篇 |
数学 | 7篇 |
物理学 | 136篇 |
出版年
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 8篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 7篇 |
2015年 | 8篇 |
2013年 | 16篇 |
2012年 | 25篇 |
2011年 | 34篇 |
2010年 | 11篇 |
2009年 | 11篇 |
2008年 | 27篇 |
2007年 | 26篇 |
2006年 | 14篇 |
2005年 | 25篇 |
2004年 | 15篇 |
2003年 | 27篇 |
2002年 | 27篇 |
2001年 | 15篇 |
2000年 | 20篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 14篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 10篇 |
1986年 | 3篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1969年 | 2篇 |
排序方式: 共有487条查询结果,搜索用时 296 毫秒
71.
Sachiko Kaidzu Kazunobu Sugihara Masahiro Sasaki Aiko Nishiaki Hiroyuki Ohashi Tatsushi Igarashi Masaki Tanito 《Photochemistry and photobiology》2023,99(4):1142-1148
Basal cells in the corneal limbus play an important role in the turnover cycle because they are the source of all cells that constitute the corneal epithelium. We examined the penetration depth of ultraviolet (UV) light in the corneal limbus and assessed the safety of Far-UV-C on stem cells in the basal area of the corneal limbus. Rats were irradiated with UV at peaks of 207, 222, 235, 254 and 311 nm while under anesthesia. The UV penetration depth in the rat corneal limbal epithelium was wavelength dependent: 311 nm UV-B and 254 nm UV-C reached the basal cells of the epithelium, and 235 nm radiation reached the middle area; however, 207 and 222 nm UV-C reached only the superficial layer of the epithelium. Porcine cornea, which is similar to the human eye in size and structure, were irradiated with 222 and 254 nm UV-C. As in rats, 222 nm UV-C reached only the superficial layer of the porcine corneal limbal epithelium. These results indicate that Far-UV-C, such as radiation of wavelengths of 207 and 222 nm, could not reach corneal epithelial stem cells, i.e. the cells remained intact. It is unlikely that the turnover of the corneal epithelium is obstructed or disrupted by exposure to Far-UV-C. 相似文献
72.
Takahashi T Asami Y Kitamura E Suzuki T Wang X Igarashi J Morohashi A Shinojima Y Kanou H Saito K Takasu T Nagase H Harada Y Kuroda K Watanabe T Kumamoto S Aoyama T Matsumoto Y Bando T Sugiyama H Yoshida-Noro C Fukuda N Hayashi N 《Chemistry & biology》2008,15(8):829-841
Pyrrole-imidazole polyamide (PIP) is a nuclease-resistant novel compound that inhibits gene expression through binding to the minor groove of DNA. Human aurora kinase-A (AURKA) and -B (AURKB) are important regulators in mitosis during the cell cycle. In this study, two specific PIPs (PIP-A and PIP-B) targeting AURKA and AURKB promoter regions were designed and synthesized, and their biological effects were investigated by several in vitro assays. PIP-A and PIP-B significantly inhibited the promoter activities, mRNA expression, and protein levels of AURKA and AURKB, respectively, in a concentration-dependent manner. Moreover, 1:1 combination treatment with both PIPs demonstrated prominent antiproliferative synergy (CI value [ED(50)] = 0.256) to HeLa cells as a result of inducing apoptosis-mediated severe catastrophe of cell-cycle progression. The novel synthesized PIP-A and PIP-B are potent and specific gene-silencing agents for AURKA and AURKB. 相似文献
73.
Chikako Nishigori Nozomi Yamano Makoto Kunisada Aiko Nishiaki-Sawada Hiroyuki Ohashi Tatsushi Igarashi 《Photochemistry and photobiology》2023,99(2):335-343
Life on earth has constantly coped with the impact of solar radiation, especially solar ultraviolet radiation (solar UV). Various biological mechanisms protect us from solar UV. New devices emitting shorter wavelengths UV-C, i.e. <254 nm emitted by conventional UV germicidal lamps, have emerged. These shorter wavelength UV-C emitting devices are useful for various purposes, including microorganism inactivation. However, as solar UV-C does not reach the earth surface, biological impacts of UV-C has been studied using 254 nm germicidal lamps, and those using shorter wavelength UV-C is rarely known. To balance the utility and risk of UV-C, the biological effect of these new UV-C emitting devices must be investigated. In addition, our knowledge of biological impacts of the wavelength-dependent entire UV (100–400 nm) must be enhanced. In this review, we briefly summarize the biological impacts of shorter wavelength UV-C. Mechanisms of UV-C-induced cellular damage and factors affecting the microorganism inactivation efficiency of UV-C have been discussed. In addition, we theoretically estimate the probable photocarcinogenic action spectrum of shorter wavelength UV-C. We propose that increasing the knowledge on UV-C will facilitate the adoption of shorter wavelength UV-C emitting new devices in an optimal and appropriate manner. 相似文献
74.
Taki M Desaki M Ojida A Iyoshi S Hirayama T Hamachi I Yamamoto Y 《Journal of the American Chemical Society》2008,130(38):12564-12565
We described here a coumarin-based dual-excitation ratiometric probe for cadmium, CadMQ. This fluorescence sensor has high quantum yields of 0.59 and 0.70 in the metal-free and Cd2+-bound forms, respectively, and has a dissociation constant of 0.16 nM for Cd2+. CadMQ is cell permeable and locates within the acidic compartments of the cells. We further show that CadMQ is a useful tool to ratiometrically probe the change in the intracellular Cd2+ levels with the use of two excited wavelengths. 相似文献
75.
Kanno K Igarashi E Zhou L Nakajima K Takahashi T 《Journal of the American Chemical Society》2008,130(17):5624-5625
Selective synthesis of linear trienes from three different alkynes was achieved in one-pot procedure using the Zr/Cu system. Zirconacyclopentadiene prepared from two different alkynes such as an alkyl-substituted alkyne and an aryl-substituted alkyne reacted with NCS gave chlorodienylzirconocene. It reacted with the third alkyne with electron-withdrawing groups in the presence of CuCl to afford the corresponding linear triene. 相似文献
76.
Rosamine-based fluorescent chemosensor for selective detection of silver(I) in an aqueous solution 总被引:1,自引:0,他引:1
The synthesis and photophysical properties of a rosamine-based fluorescent chemosensor, RosAg, for detecting Ag ion in an aqueous solution are described. This fluorescent sensor has a negligible quantum yield (<0.005) in the absence of Ag(+), whereas a significant increase in fluorescence is observed upon complexation with Ag(+) under physiological conditions. The crystal structure of the silver complex with the chelator moiety of RosAg reveals a trigonal-planar coordination geometry in which three S atoms occupy the metal center. Although a strong coordinative interaction of Ag-N is not observed in the crystal structure, the (1)H NMR experiments suggest that aniline nitrogen is likely to be associated with the Ag(+) center in the solution state. This may inhibit the photoinduced electron transfer process and result in the enhancement of fluorescence. 相似文献
77.
78.
79.
Soga T Ishikawa T Igarashi S Sugawara K Kakazu Y Tomita M 《Journal of chromatography. A》2007,1159(1-2):125-133
A method for the determination of nucleotides based on pressure-assisted capillary electrophoresis-electrospray ionization mass spectrometry (PACE-MS) is described. To prevent multi-phosphorylated species from adsorbing onto the fused-silica capillary, silanol groups were masked with phosphate ions by preconditioning the capillary with the background electrolyte containing phosphate. During preconditioning, nebulizer gas was turned off to avoid contamination of MS detector with phosphate ions. To detect nucleotides using the CE positive mode at a pH 7.5, it was necessary to apply air pressure to the inlet capillary during electrophoresis to supplement the electroosmotic flow (EOF) toward the cathode. Moreover, we exchanged the running electrolyte every analysis using the buffer replenishment system to obtain the required reproducibility. Under the optimized conditions, 14 phosphorylated species such as nucleotides, nicotinamide-adenine dinucleotides and coenzyme A (CoA) compounds were well determined in less than 20 min. The relative standard deviations (n=6) of the method were better than 0.9% for migration times and between 1.7% and 8.1% for peak areas. The detection limits for these species were between 0.5 and 1.7 micromol/L with pressure injection of 50 mbar for 30 s (30 nL) at a signal-to-noise ratio of 3. This approach is robust and quantitative compared to the previous method, and its utility is demonstrated by the analysis of intracellular nucleotides and CoA compounds extracted from Escherichia coli wild type, pfkA and pfkB knockout mutants. The methodology was used to suggest that pfkA is the main functional enzyme. 相似文献
80.
Y. Yoda H. Igarashi X.W. Zhang Y. Imai T. Mitsui I. Koyama S. Kikuta 《Hyperfine Interactions》2000,126(1-4):435-441
Multiple nuclear resonant scattering from an 57FeBO3 single crystal has been observed in the three-beam case. A change of the lifetime and a modulation of the quantum beat were
observed in our study. The high brilliance of synchrotron radiation and the high perfection of the synthetic 57FeBO3 single crystal enabled us to observe such an effect.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献