全文获取类型
收费全文 | 1220篇 |
免费 | 43篇 |
国内免费 | 5篇 |
专业分类
化学 | 957篇 |
晶体学 | 9篇 |
力学 | 26篇 |
数学 | 46篇 |
物理学 | 230篇 |
出版年
2023年 | 13篇 |
2022年 | 6篇 |
2021年 | 8篇 |
2020年 | 16篇 |
2019年 | 18篇 |
2018年 | 15篇 |
2017年 | 11篇 |
2016年 | 28篇 |
2015年 | 22篇 |
2014年 | 16篇 |
2013年 | 61篇 |
2012年 | 76篇 |
2011年 | 68篇 |
2010年 | 53篇 |
2009年 | 38篇 |
2008年 | 71篇 |
2007年 | 93篇 |
2006年 | 82篇 |
2005年 | 61篇 |
2004年 | 73篇 |
2003年 | 53篇 |
2002年 | 49篇 |
2001年 | 24篇 |
2000年 | 16篇 |
1999年 | 11篇 |
1998年 | 13篇 |
1997年 | 10篇 |
1996年 | 9篇 |
1995年 | 10篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 10篇 |
1991年 | 15篇 |
1990年 | 15篇 |
1989年 | 12篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 18篇 |
1984年 | 22篇 |
1983年 | 8篇 |
1982年 | 20篇 |
1981年 | 8篇 |
1980年 | 11篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1977年 | 9篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1974年 | 7篇 |
排序方式: 共有1268条查询结果,搜索用时 187 毫秒
951.
Development of a Sensitive Bioluminogenic Probe for Imaging Highly Reactive Oxygen Species in Living Rats
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Mako Kamiya Prof. Eiji Kobayashi Dr. Toru Komatsu Dr. Tasuku Ueno Dr. Takuya Terai Dr. Kenjiro Hanaoka Prof. Tetsuo Nagano Prof. Yasuteru Urano 《Angewandte Chemie (International ed. in English)》2015,54(49):14768-14771
A sensitive bioluminogenic probe for highly reactive oxygen species (hROS), SO3H‐APL, was developed based on the concept of dual control of bioluminescence emission by means of bioluminescent enzyme‐induced electron transfer (BioLeT) and modulation of cell‐membrane permeability. This probe enables non‐invasive visualization of physiologically relevant amounts of hROS generated deep inside the body of living rats for the first time. It is expected to serve as a practical analytical tool for investigating a wide range of biological functions of hROS in vivo. The design concept should be applicable to other in vivo bioluminogenic probes. 相似文献
952.
Chiral tether-mediated stabilization and helix-sense control of complementary metallo-double helices
A series of novel PtII-linked double helices were prepared by inter- or intrastrand ligand-exchange reactions of the complementary duplexes composed of chiral or achiral amidine dimer and achiral carboxylic acid dimer strands joined by trans-PtII–acetylide complexes with PPh3 ligands using chiral and achiral chelating diphosphines. The structure and stability of the PtII-linked double helices were highly dependent on the diphosphine structures. An interstrand ligand exchange took place with chiral and achiral 1,3-diphosphine-based ligands, resulting in trans-PtII-bridged double helices, whose helical structures were quite stable even in dimethyl sulfoxide (DMSO) due to the interstrand cross-link, whereas a 1,2-diphosphine-based ligand produced non-cross-linked cis-PtII-linked duplexes, resulting from an intrastrand ligand-exchange that readily dissociated into single strands in DMSO. When enantiopure 1,3-diphosphine-based ligands were used, the resulting trans-PtII-bridged double helices adopted a preferred-handed helical sense biased by the chirality of the bridged diphosphines. Interestingly, the interstrand ligand exchange with racemic 1,3-diphosphine toward an optically-active PtII-linked duplex, composed of chiral amidine and achiral carboxylic acid strands, was found to proceed in a diastereoselective manner, thus forming complete homochiral trans-PtII-bridged double helices via a unique chiral self-sorting. 相似文献
953.
Shun-Jun Ji Eiji Takahashi T.Tomoyoshi Takahashi C.Akira Horiuchi 《Tetrahedron letters》1999,40(52):1385
Irradiation of α-iodo ketone in hexane under a nitrogen atmosphere with a high-pressure mercury lamp (λ>300nm) at room temperature afforded the corresponding α,β-unsaturated ketones in good yield. This reaction affords a new, clean and convenient synthetic method for the α,β-unsaturated ketone. 相似文献
954.
Eiji Fujimori Tatsuya Hayashi Kazumi Inagaki H. Haraguchi 《Fresenius' Journal of Analytical Chemistry》1999,363(3):277-282
An analytical method for the determination of lanthanide elements in the bovine whole blood reference material (IAEA A-13)
has been investigated by inductively coupled plasma mass spectrometry (ICP-MS). The bovine whole blood reference material
was digested with HNO3 and HClO4, and then the pH of the digested solution was adjusted to 12 with 3 M sodium hydroxide aqueous solution. In this experimental
procedure, lanthanide elements in the blood sample were coprecipitated with iron mainly derived from heme-iron in blood itself.
In order to minimize matrix effects due to iron, excess iron in the analysis solution was removed by solvent extraction using
methyl isobutyl ketone (MIBK) prior to the determination of lanthanide elements by ICP-MS. The recoveries of all lanthanide
elements were almost quantitative in the recovery test. In consequence, it has been found that all lanthanide elements in
bovine whole blood reference material are at the wide concentration range of 0.90 pg/g for Tm ∼1880 pg/g for Ce.
Received: 2 May 1998 / Revised: 27 July 1998 / Accepted: 30 July 1998 相似文献
955.
Eiji Fujimori Tatsuya Hayashi Kazumi Inagaki H. Haraguchi 《Analytical and bioanalytical chemistry》1999,363(3):277-282
An analytical method for the determination of lanthanide elements in the bovine whole blood reference material (IAEA A-13)
has been investigated by inductively coupled plasma mass spectrometry (ICP-MS). The bovine whole blood reference material
was digested with HNO3 and HClO4, and then the pH of the digested solution was adjusted to 12 with 3 M sodium hydroxide aqueous solution. In this experimental
procedure, lanthanide elements in the blood sample were coprecipitated with iron mainly derived from heme-iron in blood itself.
In order to minimize matrix effects due to iron, excess iron in the analysis solution was removed by solvent extraction using
methyl isobutyl ketone (MIBK) prior to the determination of lanthanide elements by ICP-MS. The recoveries of all lanthanide
elements were almost quantitative in the recovery test. In consequence, it has been found that all lanthanide elements in
bovine whole blood reference material are at the wide concentration range of 0.90 pg/g for Tm ∼1880 pg/g for Ce.
Received: 2 May 1998 / Revised: 27 July 1998 / Accepted: 30 July 1998 相似文献
956.
Tatsuo Kaneyasu Yasumasa Hikosaka Masaki Fujimoto Hiroshi Iwayama Masahito Hosaka Eiji Shigemasa Masahiro Katoh 《Journal of synchrotron radiation》2017,24(5):934-938
The observation of an optical vortex beam at 60 nm wavelength, produced as the second‐harmonic radiation from a helical undulator, is reported. The helical wavefront of the optical vortex beam was verified by measuring the interference pattern between the vortex beam from a helical undulator and a normal beam from another undulator. Although the interference patterns were slightly blurred owing to the relatively large electron beam emittance, it was possible to observe the interference features thanks to the helical wavefront of the vortex beam. The experimental results were well reproduced by simulation. 相似文献
957.
Jooyoung Hahn Jie Qiu Eiji Sugisaki Lei Jia Xue-Cheng Tai & Hock Soon Seah 《高等学校计算数学学报(英文版)》2013,6(1):297-324
In this paper, we present a surface reconstruction via 2D strokes and a vector field on the strokes based on a two-step method. In the first step, from sparse strokes drawn by artists and a given vector field on the strokes, we propose a nonlinear vector interpolation combining total variation (TV) and $H^1$ regularization with a curl-free constraint for obtaining a dense vector field. In the second step, a height map is obtained by integrating the dense vector field in the first step. Jump discontinuities in surface and discontinuities of surface gradients can be well reconstructed without any surface distortion. We also provide a fast and efficient algorithm for solving the proposed functionals. Since vectors on the strokes are interpreted as a projection of surface gradients onto the plane, different types of strokes are easily devised to generate geometrically crucial structures such as ridge, valley, jump, bump, and dip on the surface. The stroke types help users to create a surface which they intuitively imagine from 2D strokes. We compare our results with conventional methods via many examples. 相似文献
958.
Junpei Fujiki Takashi Kawakita Kazuki Teshima Eiji Furuya 《Transport in Porous Media》2017,120(2):359-372
This study focuses on the development of a novel analysis technique for determining the intraparticle diffusivity \((D_{\mathrm{S}})\) and fluid film mass transfer coefficient \((k_\mathrm{F})\) from a concentration history curve of a recycle fixed-bed reactor without using the linear driving force approximation and empirical equations for the estimation of \(k_\mathrm{F}\). The recycle fixed-bed method requires lesser amounts of working fluid for experiment purposes, which is an advantage over the usual fixed-bed method. Based on the characterization results of the concentration history curves, simulated by rigorous numerical calculations, a novel analysis technique was established. The \(D_{\mathrm{S}}\) value can be determined from the experimentally obtained time at which the concentration of the curve is minimal \((t_{C\mathrm{min}})\). The \(k_\mathrm{F}\) value can be determined from the \(D_{\mathrm{S}}\) value and Biot number (Bi), which can be estimated from the experimental ratio of the maximum concentration to the minimum concentration \((c_{\max }/c_{\min })\). The \(D_{\mathrm{S}}\) and \(k_\mathrm{F}\) values of phenol adsorption on an activated carbon material were determined experimentally using the proposed analysis method. This method enables the determination of reliable adsorption kinetic parameters through a simple and economical experiment. However, appropriate experimental data must be acquired under regulated experimental conditions, especially in the case of fluctuation of the concentration history curve. 相似文献
959.
Chiral recognition mechanism of tris(4-trimethylsilylphenylcarbamate) ( 1) and tris(5-fluoro-2-methylphenylcarbamate) ( 2 ) of cellulose which are effective chiral stationary phases for HPLC were investigated using NMR spectroscopy. The phenylcarbamate derivatives are soluble in chloroform and exhibited chiral discrimination for several enantiomers in NMR as well as in HPLC. Especially, enantiomers of 2,2'-dihydroxy-1,1'-binaphthyl ( 4 ) were distinctly discriminated by 2 in 1H and 13C NMR spectroscopies. The binding geometry and dynamics between 2 and the enantiomers of 4 were investigated on the basis of spin-lattice relaxation time, 1H NMR titrations, and intermolecular NOEs in the presence of 2. These NMR data were fully consistent with the chromatographic elution order. On the basis of these results, combined with molecular modeling, the chiral discrimination mechanism is proposed. 相似文献
960.
The hypernucleus Be is investigated in an α-α-Λ three-body model using the Faddeev formalism. We use an α-α interaction in which the Pauli-forbidden
states are correctly taken into account and we employ some phenomenological potentials between the α and Λ particles. We obtained
two bound states for and , and three resonance states of . We studied the properties of these states by calculating the components and the expectation values of the potential for
each partial wave. It is found that a few channels dominate in the α (α, Λ) and states, so that the alpha-clusters or the 8Be core are still alive in the nucleus. In a case where the two alpha particles are fixed on an axis the contour plots of
the distribution of the Λ particle are shown. With the assistance of these plots one can visually understand that some of
them are shell-model-like states while others are well developed cluster-model-like states. For the structure of Be, it is concluded that the Λ particle is loosely coupled in S- and P-wave orbits about the 8Be(0+) and 8Be(2+) core states. Finally, we discuss a redundant state in the Faddeev amplitude which could arise from the treatment of symmetrization.
Received June 25, 1998; revised April 13, 1999; accepted for publication December 29, 1999 相似文献