全文获取类型
收费全文 | 364篇 |
免费 | 22篇 |
国内免费 | 1篇 |
专业分类
化学 | 267篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 30篇 |
物理学 | 88篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 5篇 |
2020年 | 15篇 |
2019年 | 7篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 10篇 |
2014年 | 14篇 |
2013年 | 21篇 |
2012年 | 29篇 |
2011年 | 35篇 |
2010年 | 18篇 |
2009年 | 32篇 |
2008年 | 22篇 |
2007年 | 25篇 |
2006年 | 32篇 |
2005年 | 15篇 |
2004年 | 16篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2001年 | 7篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1996年 | 5篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1931年 | 1篇 |
排序方式: 共有387条查询结果,搜索用时 0 毫秒
1.
2.
Komatsu H Iwasawa N Citterio D Suzuki Y Kubota T Tokuno K Kitamura Y Oka K Suzuki K 《Journal of the American Chemical Society》2004,126(50):16353-16360
The role of intracellular magnesium ions is of high interest in the fields of pharmacology and cellular biology. To accomplish the dynamic and three-dimensional imaging of intracellular Mg2+, there is a strong desire for the development of optimized Mg2+ fluorescent probes. In this paper we describe the design, synthesis, and cellular application of the three novel Mg2+ fluorescent probes KMG-101, -103, and -104. The compounds of this series feature a charged beta-diketone as a binding site specific for Mg2+ and a fluorescein residue as the fluorophore that can be excited with an Ar+ laser such as is widely used in confocal scanning microscopy. This molecular design leads to an intensive off-on-type fluorescent response toward Mg2+ ions. The two fluorescent probes KMG-103 and -104 showed suitable dissociation constants (Kd,Mg2+ = 2 mM) and nearly a 10-fold fluorescence enhancement over the intracellular magnesium ion concentration range (0.1-6 mM), allowing high-contrast, sensitive, and selective Mg2+ measurements. For intracellular applications, the membrane-permeable probe KMG-104AM was synthesized and successfully incorporated into PC12 cells. Upon application of the mitochondria uncoupler FCCP to the probe-incorporated cells, the resulting increase in the free magnesium ion concentration could be followed over time. By using a confocal microscope, the intracellular 3D magnesium ion concentration distributions were satisfactorily observed. 相似文献
3.
Influence of storage humidity on the in vitro inhalation properties of salbutamol sulfate dry powder with surface covered lactose carrier 总被引:1,自引:0,他引:1
Iida K Hayakawa Y Okamoto H Danjo K Luenberger H 《Chemical & pharmaceutical bulletin》2004,52(4):444-446
The influence of storage humidity on the in vitro inhalation properties of salbutamol sulfate dry powder with surface covered lactose carrier was investigated. In the present study, drug/carrier powder mixtures were prepared consisting of micronized salbutamol sulfate and lactose carriers with different particle surface conditions prepared by surface covering. Lactose carrier surfaces were covered with vegetable magnesium stearate (Mg-St-V) by a high-speed elliptical-rotor-type powder mixer (Theta-Composer). These powder mixtures were aerosolized by a Jethaler), and the in vitro inhalation properties of salbutamol sulfate were evaluated by a twin impinger. Compared with the powder mixed with uncovered lactose carrier, the in vitro inhalation properties of the powder mixture prepared using the surface covered lactose carrier were little decreased with increased in relative humidity (RH), showing that the in vitro inhalation properties of salbutamol sulfate were improved at high RH. Using this surface covering technique would thus be valuable for storage humidity of dry powder inhalation (DPI) with lactose carrier particles. 相似文献
4.
5.
Kotaro Hidea Hiroshi Maezawa Atsushi Ito Katsumi Kobayashi Yoshiya Furusawa Takashi Ito 《Photochemistry and photobiology》1986,44(3):417-419
The spectral throughput of a vacuum-ultraviolet irradiation system at the SOR-RING facility was examined with various combinations of aluminum-and gold-coated optical elements in a 2.2-m modified Wadsworth monochromator. We found that the optimum was a combination of an aluminum-coated collimating mirror, concave grating, and plane deflecting mirror, and a combination of a gold-coated collimating mirror, concave grating and an aluminum-coated plane deflecting mirror in the wavelength regions 190-110 nm and 110-50 nm, respectively. 相似文献
6.
The ring conformation of 2-O-methyl-1,3,4,5-tetrakis-O-tert-butyldiphenylsilyl-myo-inositol was in a twist form both in solid state and in solution. This is the first observation of a stable twist conformer induced by the introduction of bulky silyl protecting groups. 相似文献
7.
The cyclic voltammetric study of 1,10-phenanthroline—copper(II) complex was carried out in acidic buffer solution. It was found from the current—mole ratio (copper (II): 1,10-phenanthroline) relationship that the maximum coordination number of 1,10-phenanthroline—copper(II) complex was four under the present experimental condition. The reduction mechanism and kinetics of copper(II) was studied in the presence of various concentrations of 1,10-phenanthroline. 相似文献
8.
Iida K Todo H Okamoto H Danjo K Leuenberger H 《Chemical & pharmaceutical bulletin》2005,53(4):431-434
An attempt was made to produce carrier particles for dry powder inhalation with lactose carrier particles surface-coated using a Wurster fluidized bed. The lactose carrier particles were coated with lactose aqueous solution containing hydroxypropyl methyl cellulose (HPMC) as a binder using a Wurster coating apparatus. Drug/carrier powder mixtures were prepared consisting of micronized salbutamol sulfate and lactose carriers under various particle surface conditions. These powder mixtures were aerosolized by a Jethaler((R)), and the in vitro deposition properties of salbutamol sulfate were evaluated by a twin impinger. The in vitro inhalation properties of the powder mixture prepared using the coated lactose carrier differed significantly compared with those of the powder mixture prepared using the uncoated lactose carrier, indicating improvements in in vitro inhalation properties of sulbutamol sulfate. In vitro inhalation properties increased with the surface coating time. This surface coating system would thus be valuable for increasing the in vitro inhalation properties of dry powder inhalation with lactose carrier particles. 相似文献
9.
Nitric oxide (NO) is an important mediator responsible for numerous physiological phenomena. Transient levels of NO in biological systems usually range from nanomolar to micromolar concentrations, with a rapid return to basal levels normally seen following these increases. Because NO can diffuse only over a local area in limited time due to such low levels of production and due to its short life-time prior to degradation, high spatial and temporal resolutions are required for direct and continuous NO measurement if the physiological role of NO is to be investigated in any system. For such purposes, analytical methods based on bio-imaging and electrochemical techniques for the measurement of NO are useful. In this paper, we describe the successful application of these methods to a number of biological systems. Specifically, complementary application of these methods demonstrate that it is possible to detect real-time NO production from nervous tissue with high spatial and temporal resolutions. 相似文献
10.
Yasunori Inoue Hiro-o Hamaguchi Kotaro T. Yamamoto Mitsuo Tasumi Masaki Furuya 《Photochemistry and photobiology》1985,42(4):423-427
Abstract— Fluorescence spectra of native rye phytochrome were determined under different light conditions at liquid nitrogen temperature. Fluorescence spectrum of the red-light-absorbing form (Pr) had a major peak at about 685 nm (14 600 cm−1 ) and a broad sub-peak at about 515 nm (19 400 cm−1 ). The peak height at 685 nm was reduced by irradiation with monochromatic light of 640 nm, and a new peak became obvious at about 702 nm (14250 cm−1 ). This spectral change was almost completely reversed by subsequent irradiation with 700-nm light. Fluorescence spectrum of the photoequilibrium mixture of Pr and far-red-light absorbing form under continuous red light showed a sharp peak at about 685 nm having a peak height ca. 12% of Pr, and a broad sub-peak at about 508 nm (19 700 cm−1 ). Light of 730 nm did not reduce the peak height at about 685 nm but induced a new shoulder at about 699 nm (14300 cm−1 ). Monochromatic light of 640 and 700 nm given following the light of 730 nm could not reverse the spectral change at 699 nm induced by the irradiation with 730-nm light. Fluorescence spectrum of Pr in partially degraded phytochrome was similar to that in native phytochrome but the peak position in the red region was shifted by about 5 nm (100 cm−1 ) to the blue. 相似文献