全文获取类型
收费全文 | 246篇 |
免费 | 3篇 |
国内免费 | 3篇 |
专业分类
化学 | 145篇 |
晶体学 | 1篇 |
力学 | 10篇 |
数学 | 14篇 |
物理学 | 82篇 |
出版年
2021年 | 2篇 |
2020年 | 3篇 |
2018年 | 2篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 19篇 |
2012年 | 4篇 |
2011年 | 9篇 |
2010年 | 6篇 |
2009年 | 5篇 |
2008年 | 10篇 |
2007年 | 13篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 15篇 |
2003年 | 5篇 |
2002年 | 10篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1982年 | 3篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 3篇 |
1969年 | 4篇 |
1968年 | 2篇 |
1965年 | 1篇 |
1957年 | 1篇 |
1916年 | 2篇 |
1887年 | 2篇 |
排序方式: 共有252条查询结果,搜索用时 0 毫秒
31.
L.K. Fifield M.J. Hurst E.F. Garman T.J.M. Symons F. Watt K.W. Allen 《Nuclear Physics A》1980,334(1):109-126
Nine levels in the range 8.7 to 12.5 MeV in 20Ne have been investigated with the 16O(α, γ)20Ne and 16O(α, α')16O1(6.13 MeV) reactions using a differentially pumped windowless gas target. Three of the levels have not been observed previously in these reactions, and new information has been obtained for most of the others. In particular, the 11.27 MeV 1? level is shown to have T = 1, a result of relevance to a proposed parity violation experiment, and the analogue of the 1.97 MeV (3?T = 1) level in 20F is shown to lie at 12.25 MeV in 20Ne rather than at 12.39 MeV as proposed previously. In addition, the 12.25 MeV level has a width Γ < 1 keV, in contrast to the value Γ ~ 5 keV reported in other work. The electromagnetic transition rates for positive parity T = 1 states in 20Ne are compared with shell-model calculations. 相似文献
32.
33.
States of definite angular momentum projected from seven Hartree-Fock solution of 28Si are used as a basis in which to diagonalize the Hamiltonian. It is found that each of these HF solutions contributes appreciably to the low energy spectrum. 相似文献
34.
Reversible Magnetic Agglomeration: A Mechanism for Thermodynamic Control over Nanoparticle Size 下载免费PDF全文
Dr. Grant C. Bleier Dr. John Watt Prof. Dr. Chester K. Simocko Dr. Judith M. Lavin Dr. Dale L. Huber 《Angewandte Chemie (International ed. in English)》2018,57(26):7678-7681
We present a method for the synthesis and precise size control of magnetic nanoparticles in a reversible magnetic agglomeration mechanism. In this approach, nanoparticles nucleate and grow until a critical susceptibility is reached, in which magnetic attraction overcomes dispersive forces, leading to agglomeration and precipitation. This phase change in the system arrests nanoparticle growth and gives true thermodynamic control over the size of nanoparticles. We then show that increasing the alkyl chain length of the surfactant, and hence increasing steric stabilization, allows nanoparticles to grow to larger sizes before agglomeration occurs. Therefore, simply by choosing the correct surfactant, the size and magnetic properties of iron nanoparticles can be tailored for a particular application. With the continuous addition of the precursor solution, we can repeat the steps of nucleation, growth, and magnetic agglomeration indefinitely, making the approach suitable for large scale syntheses. 相似文献
35.
Pengcheng Liu Dean Yen Bairav S. Vishnugopi Varun R. Kankanallu Doğa Gürsoy Mingyuan Ge John Watt Partha P. Mukherjee Yu-chen Karen Chen-Wiegart David Mitlin 《Angewandte Chemie (International ed. in English)》2023,62(23):e202300943
Combined synchrotron X-ray nanotomography imaging, cryogenic electron microscopy (cryo-EM) and modeling elucidate how potassium (K) metal-support energetics influence electrodeposit microstructure. Three model supports are employed: O-functionalized carbon cloth (potassiophilic, fully-wetted), non-functionalized cloth and Cu foil (potassiophobic, nonwetted). Nanotomography and focused ion beam (cryo-FIB) cross-sections yield complementary three-dimensional (3D) maps of cycled electrodeposits. Electrodeposit on potassiophobic support is a triphasic sponge, with fibrous dendrites covered by solid electrolyte interphase (SEI) and interspersed with nanopores (sub-10 nm to 100 nm scale). Lage cracks and voids are also a key feature. On potassiophilic support, the deposit is dense and pore-free, with uniform surface and SEI morphology. Mesoscale modeling captures the critical role of substrate-metal interaction on K metal film nucleation and growth, as well as the associated stress state. 相似文献
36.
Chan J Huang Z Watt I Kille P Stillman M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(25):7579-7593
The ubiquitous protein metallothionein (MT) has proven to be a major player not only in the homeostasis of Cu(I) and Zn(II), but also binds all the Group 11 and 12 metals. Metallothioneins are characterised by the presence of numerous cys-x-cys and cys-cys motifs in the sequence and are found naturally with either one domain or two, linked, metal-binding domains. The use of chains of these metal-thiolate domains offers the possibility of creating chemically tuneable and, therefore, chemically dependent electrochemical or photochemical surface modifiers or as nanomachinery with nanomechanical properties. In this work, the metal-binding properties of the Cd(4)-containing domain of alpha-rhMT1a assembled into chains of two and three concatenated domains, that is, "necklaces", have been studied by spectrometric techniques, and the interactions within the structures modelled and interpreted by using molecular dynamics. These chains are metallated with 4, 8 or 12 Cd(II) ions to the 11, 22, and 33 cysteinyl sulfur atoms in the alpha-rhMT1a, alphaalpha-rhMT1a, and alphaalphaalpha-rhMT1a proteins, respectively. The effect of pH on the folding of each protein was studied by ESI-MS and optical spectroscopy. MM3/MD simulations were carried out over a period of up to 500 ps by using force-field parameters based on the reported structural data. These calculations provide novel information about the motion of the clustered metallated, partially demetallated, and metal-free peptide chains, with special interest in the region of the metal-binding site. The MD energy/time trajectory conformations show for the first time the flexibility of the metal-sulfur clusters and the bound amino acid chains. We report unexpected and very different sizes for the metallated and demetallated proteins from the combination of experimental data, with molecular dynamics simulations. 相似文献
37.
38.
In many generic combustion models, one finds that a combustionwave will develop with a specific wave speed. However, thereare possible initial temperature profiles which do not evolveinto such waves, but rather die out to the ambient temperature.There can exist, in some models, a clear distinction betweenthose initial conditions that do evolve into combustion wavesand those that do not; this is sometimes referred to as thewatershed initial condition. When fuel consumption is consideredto be negligible, analytical methods can be used to obtain theexact watershed. In this paper, we consider the problem of determiningpseudo-watersheds and ascertaining the relationship betweenthese pseudo-watersheds and the exact watersheds. In the processa novel weight-function approach for infinite spatial domainsis developed. 相似文献
39.
40.
Tiwari A Dantelle G Porfyrakis K Taylor RA Watt AA Ardavan A Briggs GA 《The Journal of chemical physics》2007,127(19):194504
Low temperature photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy of high purity ErSc(2)N@C(80) and Er(2)ScN@C(80) fullerenes reveal at least two metastable configurations of the Er(3+) ion within the cage, consistent with previous observations from x-ray diffraction. Using PLE measurements at a number of different emission wavelengths we have characterized the ground state, (4)I(152), and the first excited state, (4)I(132), of the various Er(3+) configurations and their crystal-field splitting. We present detailed energy level diagrams for the ground and excited states of the two dominant configurations of ErSc(2)N@C(80) and Er(2)ScN@C(80). 相似文献