全文获取类型
收费全文 | 123篇 |
免费 | 0篇 |
专业分类
化学 | 104篇 |
晶体学 | 1篇 |
数学 | 4篇 |
物理学 | 14篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2018年 | 1篇 |
2016年 | 1篇 |
2014年 | 2篇 |
2013年 | 13篇 |
2012年 | 7篇 |
2011年 | 13篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 2篇 |
2007年 | 4篇 |
2006年 | 5篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有123条查询结果,搜索用时 15 毫秒
71.
72.
Germ M Mazej Z Gaberscik A Häder DP 《Journal of photochemistry and photobiology. B, Biology》2002,66(1):37-46
The responses of two amphibious species, Batrachium trichophyllum and Potamogeton alpinus to different UV-B environments were studied. Plant material from natural environments, as well as from outdoor treatments was examined. In long-term outdoor experiments plants were grown under three different levels of UV-B radiation: reduced and ambient UV-B levels, and a UV-B level simulating 17% ozone depletion. The following parameters were monitored: contents of total methanol soluble UV-absorbing compounds and chlorophyll a, terminal electron transport system (ETS) activity and optimal and effective quantum yield of photosystem II. No effect of the different UV-B levels on the measured parameters was observed. The amount of UV-B absorbing compounds seems to be saturated, since no differences were observed between treatments and no increase was found in peak season, when natural UV-B levels were the highest. Physiological measurements revealed no harmful effects; neither on potential and actual photochemical efficiency, nor on terminal ETS activity. The contents of UV-B absorbing compounds were examined also in plant material sampled in low and high altitude environments during the growth season. Both species exhibited no seasonal dynamics of production of UV-absorbing compounds. The contents were variable and showed no significant differences between high and low altitude populations. 相似文献
73.
It is shown that a previously proposed simple theory, which describes the anharmonicity of the stretching vibration of the H atom in X-H…Y predicts with good precision the change in the X…Y distance, when passing from X-H…Y to X-D…Y. 相似文献
74.
J. Huikari M. Oinonen A. Algora J. Cederkäll S. Courtin P. Dessagne L. Fraile S. Franchoo H. Fynbo W.X. Huang A. Jokinen A. Knipper F. Marechal C. Miehé E. Nacher K. Peräjärvi E. Poirier L. Weissman J. Äystö 《The European Physical Journal A - Hadrons and Nuclei》2003,16(3):359-363
The β-decay of 75Sr to its mirror nucleus 75Rb was studied at the ISOLDE PSB facility at CERN by means of β-delayed γ and proton spectroscopy. The decay Q-value and β-delayed γ intensity were measured for the first time. These results, 10.60±0.22 MeV and 4.5+1.9
-0.7%, together with accurate measurements of the β-decay half-life and β-delayed proton branching ratio yielded the Gamow-Teller
strength 0.35±0.05 for the mirror transition. Implications of the results on studies of deformation effects and on the path
of the rapid proton capture process are discussed.
Received: 26 September 2002 / Accepted: 30 October 2002 / Published online: 18 February 2003
RID="a"
ID="a"e-mail: jussi.huikari@phys.jyu.lfi
Communicated by D. Schwalm 相似文献
75.
Oxidation of stainless steel surface in oxygen atmosphere was investigated by Auger electron spectroscopy (AES) depth profiling. The samples made of AISI 304L stainless steel were exposed to highly non-equilibrium oxygen atmosphere at different temperatures between 300 and 800 K and for different periods between 5 and 600 s. The degree of dissociation of oxygen molecules was of the order of 10%. A thin oxide layer formed on the stainless steel surface consisted of the iron oxide. The thickness depended on the sample temperature. At room temperature it was 7 nm, and it remained the same up to 200 °C. With further increase of temperature, the thickness of the oxide layer increased and reached 40 nm at 450 °C. The thickness was independent of exposure time. The results were explained by two mechanisms of oxide growth. Up to 200 °C the oxidation was run by electro-migration, while at higher temperatures the thermal induced migration prevailed. 相似文献
76.
Un modèle théorique est proposé en vue de reconstituer des spectres d'absorption IR des complexes du type ClH … O(CH3)2 en phase gazeuse. Ces complexes sont assimilés à des supermolécules triatomiques linéaires AH … B pour lesquelles la vibration v AH et la vibration v AH … B sont couplées par un potentiel anharmonique. Le terme couplant ces deux vibrations peut être atteint de manière précise par la connaissance de l'évolution du spectre en fonction de la température. Le modèle permet de reproduire de façon satisfaisante les spectres I.R. de ClH … O(CH3)2 et de ClD … O(CH3)2. On reproduit également mais de façon moins précise les spectres de quelques complexes voisins pour lesquels on ne possède pas de résultats en fonction de la température. 相似文献
77.
The freezing transition in a classical three-dimensional system of rounded hard cubes with fixed, equal orientations is studied by computer simulation and fundamental-measure density functional theory. By switching the rounding parameter s from zero to one, one can smoothly interpolate between cubes with sharp edges and hard spheres. The equilibrium phase diagram of rounded parallel hard cubes is computed as a function of their volume fraction and the rounding parameter s. The second order freezing transition known for oriented cubes at s = 0 is found to be persistent up to s = 0.65. The fluid freezes into a simple-cubic crystal which exhibits a large vacancy concentration. Upon a further increase of s, the continuous freezing is replaced by a first-order transition into either a sheared simple cubic lattice or a deformed face-centered cubic lattice with two possible unit cells: body-centered orthorhombic or base-centered monoclinic. In principle, a system of parallel cubes could be realized in experiments on colloids using advanced synthesis techniques and a combination of external fields. 相似文献
78.
Popelka A Novák I Lehocký M Chodák I Sedliačik J Gajtanska M Sedliačiková M Vesel A Junkar I Kleinová A Spírková M Bílek F 《Molecules (Basel, Switzerland)》2012,17(1):762-785
Polyethylene (PE) is one of the most widely used polymers in many industrial applications. Biomedical uses seem to be attractive, with increasing interest. However, PE it prone to infections and its additional surface treatment is indispensable. An increase in resistance to infections can be achieved by treating PE surfaces with substances containing antibacterial groups such as triclosan (5-Chloro-2-(2,4-dichlorophenoxy)phenol) and chlorhexidine (1,1'-Hexamethylenebis[5-(4-chlorophenyl)biguanide]). This work has examined the impact of selected antibacterial substances immobilized on low-density polyethylene (LDPE) via polyacrylic acid (PAA) grafted on LDPE by low-temperature barrier discharge plasma. This LDPE surface treatment led to inhibition of Escherichia coli and Staphylococcus aureus adhesion; the first causes intestinal disease, peritonitis, mastitis, pneumonia, septicemia, the latter is the reason for wound and urinary tract infections. 相似文献
79.
Alenka Možir Matija Strlič Tanja Trafela Irena Kralj Cigić Jana Kolar Viorica Deselnicu Gerrit de Bruin 《Applied Physics A: Materials Science & Processing》2011,104(1):211-217
Historic parchment is an extremely complex material, not only due to the various methods of production used and various past
environmental histories of objects, but also due to its inhomogeneous structure. Many traditional methods of characterisation
are empirical, but useful since they have gained recognition by the end-users. In this paper, we investigated the shrinkage
temperature of collagen and the influence of lipids contained in parchment on the measurements. While the content of lipids
does not seem to significantly affect shrinkage temperature measurements themselves, it strongly affects the decrease of shrinkage
temperature of collagen during degradation, and thus its thermomechanical properties. This confirms the high importance of
lipid peroxidation during degradation of parchment. 相似文献
80.
J. C. Marechal 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(4):609-618
Pure and peroxided PVC films were irradiated under monochromatic ultraviolet light between 300 and 400 nm. The degradation state of PVC is measured by means of carbonyl absorption in the infrared spectra and polyene content by UV spectroscopy. The initial rate of carbonyl formation depends on the wavelengths and oxidized impurities content. Peroxided PVC is oxidized faster than pure PVC with wavelengths above 320 nm. Two hazardous ranges of wavelengths have been detected: 300–320 and 350–370 nm. Good protection of PVC against UV radiation can be assured by the exclusion of wavelengths under 380 nm. 相似文献