全文获取类型
收费全文 | 1231篇 |
免费 | 46篇 |
国内免费 | 5篇 |
专业分类
化学 | 974篇 |
晶体学 | 10篇 |
力学 | 6篇 |
数学 | 66篇 |
物理学 | 226篇 |
出版年
2023年 | 10篇 |
2022年 | 11篇 |
2021年 | 15篇 |
2020年 | 15篇 |
2019年 | 24篇 |
2018年 | 15篇 |
2017年 | 19篇 |
2016年 | 26篇 |
2015年 | 25篇 |
2014年 | 33篇 |
2013年 | 78篇 |
2012年 | 64篇 |
2011年 | 97篇 |
2010年 | 44篇 |
2009年 | 38篇 |
2008年 | 88篇 |
2007年 | 76篇 |
2006年 | 72篇 |
2005年 | 77篇 |
2004年 | 78篇 |
2003年 | 70篇 |
2002年 | 74篇 |
2001年 | 14篇 |
2000年 | 17篇 |
1999年 | 13篇 |
1998年 | 14篇 |
1997年 | 11篇 |
1996年 | 15篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1986年 | 3篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1982年 | 6篇 |
1981年 | 13篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1964年 | 3篇 |
1961年 | 2篇 |
排序方式: 共有1282条查询结果,搜索用时 15 毫秒
81.
This article describes the preparation and liquid crystalline properties of a new homologous series of 4-(4-bromopropyloxy)-4’- (4-alkyloxybenzylidene)anilines in which the phenyl ring is armed by a bromopropyloxy chain.The thermal behavior and mesomorphic properties of the synthesized compounds were studied with particular attention given to the correlation between their phase transition temperatures and anisotropic change influenced by molecular structure.All the members displayed enantiotropic smectic phase except for the homologue with the longest alkyloxy chain(R = C18H37),exhibiting only monotropic characteristic. The presence of bromine atom from the propyloxy side chain is found to be capable of altering and influencing the mesomorphic properties. 相似文献
82.
Conformational and Intermolecular Interaction Dynamics of Photolyase/Cryptochrome Proteins Monitored by the Time‐Resolved Diffusion Technique 下载免费PDF全文
Cryptochrome (CRY), a blue light sensor protein, possesses a similar domain structure to photolyase (PHR) that, upon absorption of light, repairs DNA damage. In this review, we compare the reaction dynamics of these systems by monitoring the reaction kinetics of conformational change and intermolecular interaction change based on time‐dependent diffusion coefficient measurements obtained by using the pulsed laser‐induced transient grating technique. Using this method, time‐dependent biomolecular interactions, such as transient dissociation reactions in solution, have been successfully detected in real time. Conformational change in (6‐4) PHR has not been detected after the photoexcitation by monitoring the diffusion coefficient. However, the repaired DNA dissociates from PHR with a time constant of 50 μs, which must relate to a minor conformational change. However, CRY exhibits a considerable diffusion change with a time constant of 400 ms, which indicates that the protein–solvent interaction is changed by the conformational change. The C‐terminal domain of CRY is shown to be responsible for this change. 相似文献
83.
Masato Nagata 《Meccanica》2016,51(12):3015-3023
84.
Masato Abe 《Tetrahedron letters》2010,51(15):2071-8391
Production of a wide variety of cardiolipin (CL) analogues is critical for studying molecular mechanism of diverse biological functions of CL in mitochondria. We describe a concise procedure for the synthesis of CL using a phosphoramidite approach, which allows for the production of diverse CL analogues bearing linoleic acid(s) at any position on the glycerol backbone. 相似文献
85.
The dynamic changes in ferroelectric liquid crystal (FLC) molecular alignments under an applied electric field are examined
by observing the formation of conoscopic figures with a time resolution of 0.1 ms. Close agreements between observed and simulated
conoscopic figures under low voltage (30 V) were obtained. Under high voltage (120 V), however, the observed conoscopic figures
became blurred between 0.8 ms and 1.1 ms after reversal of the electric field. The light scattering producing the blurriness
occurred due to the development of fast transient molecular alignments during the switching transition above the applied voltage
70 V. 相似文献
86.
The spin torque and zeta force, which govern spin dynamics, are studied by using monoatoms in their steady states. We find nonzero local spin torque in transition metal atoms, which is in balance with the counter torque, the zeta force. We show that d-orbital electrons have a crucial effect on these torques. Nonzero local chirality density in transition metal atoms is also found, though the electron mass has the effect to wash out nonzero chirality density. Distribution patterns of the chirality density are the same for Sc–Ni atoms, though the electron density distributions are different. 相似文献
87.
Water-soluble constituents of dill 总被引:1,自引:0,他引:1
From the water-soluble portion of the methanol extract of dill (fruit of Anethum graveolens L.), which has been used as a spice and medicine, thirty-three compounds, including a new monoterpenoid, six new monoterpenoid glycosides, a new aromatic compound glucoside and a new alkyl glucoside were obtained. Their structures were clarified by spectral investigation. 相似文献
88.
Masato Doura Hiroyuki Aota Akira Matsumoto 《Journal of polymer science. Part A, Polymer chemistry》2004,42(9):2192-2201
Novel amphiphilic network polymers consisting of nonpolar, short primary polymer chains and polar, long crosslink units were prepared, and the swelling behavior of resulting amphiphilic gels is discussed by focusing on the influence of characteristic dangling chains; that is, benzyl methacrylate (BzMA) was copolymerized with tricosaethylene glycol dimethacrylate [CH2?C(CH3)CO(OCH2CH2)23OCOC(CH3)?CH2, PEGDMA‐23] in the presence of lauryl mercaptan as a chain‐transfer agent because BzMA forms nonpolar, short primary polymer chains and PEGDMA‐23 as a crosslinker contains a polar, long poly(oxyethylene) unit. The enhanced incorporation of dangling chains into the network polymer was brought by shortening the primary polymer chain length, and copolymerization with methoxytricosaethylene glycol methacrylate, a mono‐ene counterpart of PEGDMA‐23, enforced the incorporation of flexible dangling poly(oxyethylene) chains into the network polymer, although the former dangling chains as terminal parts of primary poly(BzMA) chains were rather rigid. Then, the influence of characteristic dangling chains on the swelling behavior of amphiphilic gels was examined in mixed solvents consisting of nonpolar t‐butylbenzene and polar methanol. The profiles of the solvent‐component dependencies of the swelling ratios were characteristic of amphiphilic gels. The introduction of dangling poly(oxyethylene) chains led not only to an increased swelling ratio but also to sharpened swelling behavior of amphiphilic gels. The swelling response of amphiphilic gels was checked by changing the external solvent polarity. The dangling chains with freely mobile end segments influenced the swelling response of gels. The amphiphilic gels with less entangled, collapsed crosslink units exhibited faster swelling response than the ones with more entangled, collapsed primary polymer chains. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2192–2201, 2004 相似文献
89.
Masato Hasebe Catherine Lazare Paul de Mayo Alan C. Weedon 《Tetrahedron letters》1981,22(51):5149-5152
Irradiation of a number of aromatic hydrocarbons adsorbed on alumina in the presence of ferric chloride leads to monochlorination. 相似文献
90.