全文获取类型
收费全文 | 1191篇 |
免费 | 50篇 |
国内免费 | 2篇 |
专业分类
化学 | 876篇 |
晶体学 | 9篇 |
力学 | 29篇 |
数学 | 38篇 |
物理学 | 291篇 |
出版年
2021年 | 13篇 |
2020年 | 27篇 |
2019年 | 17篇 |
2018年 | 10篇 |
2017年 | 13篇 |
2016年 | 23篇 |
2015年 | 20篇 |
2014年 | 23篇 |
2013年 | 40篇 |
2012年 | 60篇 |
2011年 | 70篇 |
2010年 | 37篇 |
2009年 | 30篇 |
2008年 | 68篇 |
2007年 | 67篇 |
2006年 | 71篇 |
2005年 | 72篇 |
2004年 | 78篇 |
2003年 | 48篇 |
2002年 | 35篇 |
2001年 | 41篇 |
2000年 | 27篇 |
1999年 | 18篇 |
1998年 | 7篇 |
1997年 | 15篇 |
1996年 | 17篇 |
1995年 | 17篇 |
1994年 | 22篇 |
1993年 | 16篇 |
1992年 | 12篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 12篇 |
1988年 | 10篇 |
1987年 | 11篇 |
1986年 | 7篇 |
1985年 | 16篇 |
1984年 | 15篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 13篇 |
1979年 | 11篇 |
1978年 | 12篇 |
1976年 | 13篇 |
1975年 | 10篇 |
1974年 | 8篇 |
1973年 | 8篇 |
1969年 | 7篇 |
1967年 | 6篇 |
排序方式: 共有1243条查询结果,搜索用时 46 毫秒
1.
Optical Review - This paper demonstrates a method to estimate the depth of a fluorescence object in turbid media using dual-wavelength excited photodynamic diagnosis, to aid in the invasion depth... 相似文献
2.
Chikashi Shinagawa Yusuke Morikawa Shin-ichi Nishimura Hiroshi Ushiyama Atsuo Yamada Koichi Yamashita 《Journal of computational chemistry》2019,40(1):237-246
Na2FePO4F is a promising cathode material for a Na-ion battery because of its high electronic capacity and good cycle performance. In this work, first principle calculations combined with cluster expansion and the Monte Carlo method have been applied to analyze the charge and discharge processes of Na2FePO4F by examining the voltage curve and the phase diagram. As a result of the density functional theory calculation and experimental verification with structural analysis, we found that the most stable structure of Na1.5FePO4F has the P21/b11 space group, which has not been reported to date. The estimated voltage curve has two clear plateaus caused by the two-phase structure composed of P21/b11 Na1.5FePO4F and Pbcn Na2FePO4F or Na1FePO4F and separated along the c-axis direction. The phase diagram shows the stability of the phase-separated structure. Considering that Na2FePO4F has diffusion paths in the a- and c-axis directions, Na2FePO4F has both innerphase and interphase diffusion paths. We suggest that the stable two-phase structure and the diffusion paths to both the innerphase and interphases are a key for the very clear plateau. We challenge to simulate a nonequilibrium state at high rate discharge with high temperature by introducing a coordinate-dependent chemical potential. The simulation shows agreement with the experimental discharge curve on the disappearance of the two plateaus. © 2018 Wiley Periodicals, Inc. 相似文献
3.
4.
5.
Nakayama Masanobu Nishimura Norimitsu Kondo Yuki Takeda Hayami Kasuga Toshihiro 《Journal of Solid State Electrochemistry》2017,21(4):1137-1143
Journal of Solid State Electrochemistry - We demonstrate the Laplace transform (LT) impedance technique for measuring electrochemical lithiation and delithiation in the two-phase system of spinel... 相似文献
6.
Dr. Pengfei Wu Prof. Dr. Adriana Pietropaolo Dr. Mariagrazia Fortino Dr. Masayoshi Bando Prof. Dr. Katsuhiro Maeda Dr. Tatsuya Nishimura Shuhei Shimoda Dr. Hiroyasu Sato Prof. Dr. Naofumi Naga Prof. Dr. Tamaki Nakano 《Angewandte Chemie (International ed. in English)》2023,62(29):e202305747
Optically active, hyperbranched, poly(fluorene-2,4,7-triylethene-1,2-diyl) [poly(fluorenevinylene)] derivatives bearing a neomenthyl group and a pentyl group at the 9-position of the fluorene backbone at various ratios acted as a chirality donor (host polymers) efficiently included naphthalene, anthracene, pyrene, 9-phenylanthracene, and 9,10-diphenyanthracene as a chirality acceptor (guest molecules) in their interior space in film as well as in solution, with the guest molecules exhibiting intense circular dichroism through chirality transfer with chirality amplification. The efficiency of the chirality transfer was much higher with higher-molar-mass polymers than lower-molar-mass ones as well as with hyperbranched polymers compared to the analogous linear ones. The hyperbranched polymers include the small molecules in their complex structure without any specific interactions at various stoichiometries. The included molecules may have ordered intermolecular arrangement that may be somewhat similar to those of liquid crystals. Naphthalene, anthracene, and pyrene included in the polymer exhibited efficient circularly polarized luminescence, where the chirality was remarkably amplified in excited states, and anthracene exhibited especially high anisotropies in the emission on the order of 10−2. 相似文献
7.
Akira Nishimura Ryouga Shimada Yoshito Sakakibara Akira Koshio Eric Hu 《Molecules (Basel, Switzerland)》2021,26(10)
The aim of this study is to clarify the effect of doped metal type on CO2 reduction characteristics of TiO2 with NH3 and H2O. Cu and Pd have been selected as dopants for TiO2. In addition, the impact of molar ratio of CO2 to reductants NH3 and H2O has been investigated. A TiO2 photocatalyst was prepared by a sol-gel and dip-coating process, and then doped with Cu or Pd fine particles by using the pulse arc plasma gun method. The prepared Cu/TiO2 film and Pd/TiO2 film were characterized by SEM, EPMA, TEM, STEM, EDX, EDS and EELS. This study also has investigated the performance of CO2 reduction under the illumination condition of Xe lamp with or without ultraviolet (UV) light. As a result, it is revealed that the CO2 reduction performance with Cu/TiO2 under the illumination condition of Xe lamp with UV light is the highest when the molar ratio of CO2/NH3/H2O = 1:1:1 while that without UV light is the highest when the molar ratio of CO2/NH3/H2O = 1:0.5:0.5. It is revealed that the CO2 reduction performance of Pd/TiO2 is the highest for the molar ratio of CO2/NH3/H2O = 1:1:1 no matter the used Xe lamp was with or without UV light. The molar quantity of CO per unit weight of photocatalyst for Cu/TiO2 produced under the illumination condition of Xe lamp with UV light was 10.2 μmol/g, while that for Pd/TiO2 was 5.5 μmol/g. Meanwhile, the molar quantity of CO per unit weight of photocatalyst for Cu/TiO2 produced under the illumination condition of Xe lamp without UV light was 2.5 μmol/g, while that for Pd/TiO2 was 3.5 μmol/g. This study has concluded that Cu/TiO2 is superior to Pd/TiO2 from the viewpoint of the molar quantity of CO per unit weight of photocatalyst as well as the quantum efficiency. 相似文献
8.
Dr. Neil J. Stewart Hitomi Nakano Shuto Sugai Mitsushi Tomohiro Yuki Kase Yoshiki Uchio Dr. Toru Yamaguchi Yujirou Matsuo Dr. Tatsuya Naganuma Dr. Norihiko Takeda Dr. Ikuya Nishimura Dr. Hiroshi Hirata Dr. Takuya Hashimoto Dr. Shingo Matsumoto 《Chemphyschem》2021,22(10):915-923
Hyperpolarized [1-13C]fumarate is a promising magnetic resonance imaging (MRI) biomarker for cellular necrosis, which plays an important role in various disease and cancerous pathological processes. To demonstrate the feasibility of MRI of [1-13C]fumarate metabolism using parahydrogen-induced polarization (PHIP), a low-cost alternative to dissolution dynamic nuclear polarization (dDNP), a cost-effective and high-yield synthetic pathway of hydrogenation precursor [1-13C]acetylenedicarboxylate (ADC) was developed. The trans-selectivity of the hydrogenation reaction of ADC using a ruthenium-based catalyst was elucidated employing density functional theory (DFT) simulations. A simple PHIP set-up was used to generate hyperpolarized [1-13C]fumarate at sufficient 13C polarization for ex vivo detection of hyperpolarized 13C malate metabolized from fumarate in murine liver tissue homogenates, and in vivo 13C MR spectroscopy and imaging in a murine model of acetaminophen-induced hepatitis. 相似文献
9.
Iron–Oxalato Framework with One‐Dimensional Open Channels for Electrochemical Sodium‐Ion Intercalation 下载免费PDF全文
Dr. Xianfen Wang Ryosuke Kurono Dr. Shin‐ichi Nishimura Dr. Masashi Okubo Prof. Atsuo Yamada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(3):1096-1101
Discovery of a new class of ion intercalation compounds is highly desirable due to its relevance to various electrochemical devices, such as batteries. Herein, we present a new iron–oxalato open framework, which showed reversible Na+ intercalation/extraction. The hydrothermally synthesized K4Na2[Fe(C2O4)2]3 ? 2 H2O possesses one‐dimensional open channels in the oxalato‐bridged network, providing ion accessibility up to two Na+ per the formula unit. The detailed studies on the structural and electronic states revealed that the framework exhibited a solid solution state almost entirely during Na+ intercalation/extraction associated with the reversible redox of Fe. The present work demonstrates possibilities of the oxalato frameworks as tunable and robust ion intercalation electrode materials for various device applications. 相似文献
10.
Synergic Catalysis of PdCu Alloy Nanoparticles within a Macroreticular Basic Resin for Hydrogen Production from Formic Acid 下载免费PDF全文
Prof. Dr. Kohsuke Mori Dr. Hiromasa Tanaka Masahiro Dojo Prof. Dr. Kazunari Yoshizawa Prof. Dr. Hiromi Yamashita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(34):12085-12092
Highly dispersed PdCu alloy nanoparticles have been successfully prepared within a macroreticular basic resin bearing ?N(CH3)2 functional groups. This previously unappreciated combination of alloy is first proven to be responsible for the efficient production of high‐purity H2 from formic acid (HCOOH) dehydrogenation for chemical hydrogen storage. By the addition of Cu, the electronically promoted Pd sites show significantly higher catalytic activity as well as a better tolerance towards CO poisoning as compared to their monometallic Pd counterparts. Experimental and DFT calculation studies revealed not only the synergic alloying effect but also cooperative action by the ?N(CH3)2 groups within the resin play crucial roles in achieving exceptional catalytic performances. In addition to the advantages such as, facile preparation method, free of additives, recyclable without leaching of active component, and suppression of unfavorable CO formation less than 3 ppm, the present catalytic system is cost‐effective because of the superior catalytic activity compared with that of well‐established precious PdAg or PdAu catalysts. The present catalytic system is particularly desirable for an ideal hydrogen vector in terms of potential industrial application for fuel cells. 相似文献