全文获取类型
收费全文 | 365篇 |
免费 | 18篇 |
专业分类
化学 | 295篇 |
晶体学 | 11篇 |
力学 | 2篇 |
数学 | 19篇 |
物理学 | 56篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 5篇 |
2018年 | 10篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 14篇 |
2013年 | 20篇 |
2012年 | 34篇 |
2011年 | 27篇 |
2010年 | 16篇 |
2009年 | 19篇 |
2008年 | 34篇 |
2007年 | 24篇 |
2006年 | 20篇 |
2005年 | 18篇 |
2004年 | 19篇 |
2003年 | 16篇 |
2002年 | 13篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 7篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 2篇 |
1968年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有383条查询结果,搜索用时 31 毫秒
101.
The present paper describes materials of polypeptide-commodity polymer hybrids from poly(vinyl alcohol) (PVA) and poly(sodium α,β-D ,L -aspartate) ( 1 ). Miscible blend films of polypeptide 1 and PVA were prepared by the solvent-cast method from a homogeneous aqueous solution. Differential scanning calorimetry. Fourier transform infrared, and scanning electron microscopy combined with energy dispersive X-ray spectroscopy (EDX) were used to investigate the blends. It was revealed that 1 and PVA are miscible in a wide range of compositions. 相似文献
102.
Hiroaki Matsushita Takafumi Ochiai Katsuhiko Mikajiri Akinori Katsui 《Journal of Physics and Chemistry of Solids》2005,66(11):1937-1939
CuInGeSe4 quaternary compounds are known to have a chalcopyrite-like structure and have band gaps of about 1.3 eV, suitable for optimum conversion efficiency for solar cells. We have prepared the CuInGeSe4 thin films by the selenization method using the Cu-In-Ge evaporated layer precursors. The analyses of X-ray diffraction show that the single phase of CuInGeSe4 is obtained by the selenization of precursors at 450-500 °C. The SEM observation of film surface shows that the grain sizes are in the order of 1-2 μm. The band gaps of selenized films close to 1.6 eV are wider than that of bulk crystals (about 1.3 eV). These films have p-type conduction and higher electrical resistivities than more 105 Ω cm at room temperature. 相似文献
103.
Yosuke Shibata Akinori Takasu 《Journal of polymer science. Part A, Polymer chemistry》2009,47(21):5747-5759
In this article, we describe the one‐step synthesis of polyesters having pendent hydroxyl groups by Lewis acid‐catalyzed, regioselective, dehydration polycondensations of diols (glycerol and sorbitol) and dicarboxylic acids [tartaric acid (TA) and malic acid (MA)] containing pendent hydroxyl groups, using low temperature polycondensation technique. Direct polycondensations of TA or MA and 1,9‐nonanediol catalyzed by scandium trifluoromethanesulfonate [Sc(OTf)3] successfully yielded linear polyesters having hydroxyl functionality (Mn = ca. 1.0 × 104). To demonstrate the reactivity of the pendent hydroxyl group, a glycosidation was performed. Poly(nonamethylene L ‐malate) showed significant higher biodegradability, compared with poly(nonamethylene L ‐tartrate) or poly(nonamethylene succinate). Stable poly(nonamethylene L ‐tartrate) emulsion could be prepared using poly(vinyl alcohol) as the surfactant, although emulsions consisting of poly(nonamethylene succinate) were unstable and phase‐separated within a few days. Furthermore, direct polycondensations of TA and diethylene glycol (DEG) or triethylene glycol (TEG) successfully produced water‐soluble polyesters having hydroxyl groups. This new polycondensation system may be extremely effective not only for advanced material design using functional monomers but also for effective utilization of biomass resources as chemical substances. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5747–5759, 2009 相似文献
104.
105.
Akinori Tanaka Yuitsu TakedaTazumi Nagasawa Kazutoshi Takahashi 《Solid State Communications》2003,126(4):191-196
We have carried out a photoemission study using synchrotron radiation of dodecanethiolate (DT)-passivated Au nanoparticles supported on the highly oriented pyrolytic graphite substrates. From detailed line-shape analyses of Au 4f core-level photoemission spectra of DT-passivated Au nanoparticles, it was found that Au 4f core-level spectra consist of two components. We attribute these components to the inner Au atoms and surface Au atoms bonded to surface dodecanethiolates. From these results, we discuss the chemical states of the present DT-passivated Au nanoparticles. 相似文献
106.
Williams BB Sucheta A Dong R Sakata Y Iwasaki A Burke G Grinberg O Lesniewski P Kmiec M Swartz HM 《Radiation measurements》2007,42(6-7):1094-1098
In vivo electron paramagnetic resonance (EPR) tooth dosimetry provides a means for non-invasive retrospective assessment of personal radiation exposure. While there is a clear need for such capabilities following radiation accidents, the most pressing need for the development of this technology is the heightened likelihood of terrorist events or nuclear conflicts. This technique will enable such measurements to be made at the site of an incident, while the subject is present, to assist emergency personnel as they perform triage for the affected population. At Dartmouth Medical School this development is currently being tested with normal volunteers with irradiated teeth placed in their mouths and with patients who have undergone radiation therapy. Here we describe progress in practical procedures to provide accurate and reproducible in vivo dose estimates. 相似文献
107.
The Hubbard model on the kagome lattice has highly degenerate ground states (the flat lowest band) in the corresponding single-electron problem and exhibits the so-called flat-band ferromagnetism in the many-electron ground states as was found by Mielke [J. Phys. A 24, L73 (1991)]]. Here we study the model obtained by adding extra hopping terms to the above model. The lowest single-electron band becomes dispersive, and there is no band gap between the lowest band and the other band. We prove that, at half filling of the lowest band, the ground states of this perturbed model remain saturated ferromagnetic if the lowest band is nearly flat. 相似文献
108.
Taniguchi Hiroshi Kurosawa Akinori Tanosaki Shinji Devaraj B. Inaba Humio 《Optical and Quantum Electronics》2000,32(2):125-135
The first laser action of active-particles of 1–2 m in diameter, red fluorescent-powder (FP), dispersed in nonactive (nonlasing) 100 m-sized liquid microdroplets is reported. Lasing characteristics of FP-containing microdroplets by mixing Intralipid-10% as highly scattering turbid media are also described. Well-defined lasing thresholds can be confirmed from the FP-dispersed pure microdroplets, and lowered lasing threshold along with enhanced lasing emission is achieved by appropriately mixing the Intralipid-10% solution. Lasing threshold in these microdroplets can be determined not through the spectral narrowing features but through the input–output data. We believe that these new microdroplet configurations offer one of the new categories of lasing media and they seem also to simulate to some biological pigments or organelles contained in cells and small tissues. 相似文献
109.
Akinori Kubo Shinsuke Nakahara Ryoichi Iwata Katsuhiro Takahashi Tadashi Arai 《Tetrahedron letters》1980,21(33):3207-3208
A new isoquinolinequinone antibiotic, mimocin(2), has been isolated from the strain of Streptomyces lavendulae. The structure of mimocin has been deduced from mass and PMR spectral data and confirmed by its synthesis. 相似文献
110.