全文获取类型
收费全文 | 125篇 |
免费 | 10篇 |
专业分类
化学 | 112篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 4篇 |
物理学 | 17篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 4篇 |
2019年 | 9篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 8篇 |
2014年 | 7篇 |
2013年 | 7篇 |
2012年 | 12篇 |
2011年 | 11篇 |
2010年 | 10篇 |
2009年 | 8篇 |
2008年 | 5篇 |
2007年 | 4篇 |
2006年 | 7篇 |
2005年 | 2篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有135条查询结果,搜索用时 78 毫秒
101.
102.
Jan Tomforde Saskia Buller Marscha Ried Wolfgang Bensch Daniel Wamwangi Markus Heidelmann Matthias Wuttig 《Solid State Sciences》2009,11(3):683-687
Se substituted GeSb2Te4 films have been investigated for property contrast using electrical four-point-probe measurements, in-situ X-ray diffraction (XRD), a static tester probing the optical changes and atomic force microscopy (AFM). The temperature dependent sheet resistance measurements show two transitions at 125 and 262 °C. The first transition at 125 °C is accompanied by a large resistance change of three orders of magnitude. The resistance change for the second step is less pronounced. In-situ X-ray scattering experiments evidence that the first steep change in resistance is due to an amorphous → NaCl type structural transformation. The second change is caused by the transition from the cubic structure to the stable rhombohedral phase. Power–time effect (PTE) diagrams recorded to monitor the optical contrast of the films upon laser irradiation exhibit a fast recrystallization time of about 100 ns. The change of film roughness and topography between the amorphous and crystalline phase has been determined by AFM. 相似文献
103.
Sandra Künzler Saskia Rathjen Anastasia Merk Dr. Marc Schmidtmann Prof. Dr. Thomas Müller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(66):15123-15130
A new NMR-based Lewis acidity scale is suggested and its application is demonstrated for a family of silyl Lewis acids. The reaction of p-fluorobenzonitrile (FBN) with silyl cations that are internally stabilized by interaction with a remote chalcogenyl or halogen donor yields silylated nitrilium ions with the silicon atom in a trigonal bipyramidal coordination environment. The 19F NMR chemical shifts and the 1J(CF) coupling constants of these nitrilium ions vary in a predictable manner with the donor capability of the stabilizing group. The spectroscopic parameters are suitable probes for scaling the acidity of Lewis acids. These new probes allow for the discrimination between very similar Lewis acids, which is not possible with conventional NMR tests, such as the well-established Gutmann–Beckett method. 相似文献
104.
Lambrechts SA Aalders MC Verbraak FD Lagerberg JW Dankert JB Schuitmaker JJ 《Journal of photochemistry and photobiology. B, Biology》2005,79(1):51-57
BACKGROUND: Photodynamic inactivation (PDI) employs visible light and a photosensitizer to inactivate cells. The technique is currently clinically used for the treatment of several malignancies. However, the PDI of microorganisms still remains in the research phase. PURPOSE: To study the effect of human blood plasma and human serum albumin (HSA) on the PDI of Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. METHODS: PDI experiments were performed using white light (30 mW cm-2) and the cationic 5-phenyl-10,15,20-tris(N-methyl-4-pyridyl)porphyrin chloride (TriP[4]) as photosensitizer. RESULTS: The microorganisms could be successfully photoinactivated by TriP[4] when suspended in phosphate buffered saline (PBS). In this medium, P. aeruginosa was the most resistant microorganism. Changing the suspending medium from PBS to human blood plasma reduced the PDI of all three microorganisms. In human blood plasma C. albicans was the most resistant microorganism. The same results were obtained with 4.5% and 7% HSA/PBS suspensions. CONCLUSIONS: Albumin inhibits the PDI of S. aureus, P. aeruginosa and C. albicans in a dose dependent manner. However, our results are encouraging towards the potential future application of PDI for the treatment of superficial wound infections caused by S. aureus, P. aeruginosa and C. albicans. 相似文献
105.
106.
Chemakin I Cianciolo V Cole BA Fernow R Frawley AD Gilkes M Gushue S Hartouni EP Hiejima H Justice M Kang JH Kirk H Maeda N McGrath RL Mioduszewski S Morrison D Moulson M Namboodiri MN Rai G Read K Remsberg L Rosati M Shin Y Soltz RA Sorensen S Thomas JH 《Physical review letters》2000,85(23):4868-4871
The first detailed measurements of the centrality dependence of strangeness production in p-A collisions are presented. Lambda and K(S) dn/dy distributions from 17.5 GeV/ c p-Au collisions are shown as a function of "grey" track multiplicity and the estimated number of collisions, nu, made by the proton. The nu dependence of the Lambda yield deviates from a scaling of p-p data by the number of participants, increasing faster than this scaling for nu=5 and saturating for larger nu. A slower growth in K(S) multiplicity with nu is observed, consistent with a weaker nu dependence of K&Kmacr; production than YK production. 相似文献
107.
Rob A. C. Keulers Angelique R. de Roon Saskia de Roode Ad D. Tates 《Photochemistry and photobiology》1998,67(4):426-432
The DNA-damaging potential of ultraviolet-B (UVB) radiation was investigated by analyzing the frequency and origin of micronuclei (MN) in cytokinesis-blocked, binucleated (BN) peripheral blood lymphocytes (PBL) and cloning efficiencies (CE) of PBL after exposure to different fluences of UVB. In total, PBL obtained from five normal donors were investigated. The PBL from all donors showed a dose-related, linear-quadratic increase in the frequency of MN per 1000 BN cells and in the frequency of micronucleated BN cells. In two experiments the origin of UVB-induced MN was studied by analyzing MN for the presence or absence of centromeres by applying the MN assay in combination with a centromeric probe and fluorescence in situ hybridization. This revealed, for the first time, that UVB-induced MN were centromere negative, indicating that UVB acted exclusively as a clastogenic agent in the tested dose range. The PBL from all donors showed a clear dose-dependent decrease in CE, after UVB exposure. The UVB-exposed PBL from all donors showed an inverse relationship between the induction of MN and the decrease in CE, but regression analysis revealed no correlation between the induction of MN and the decrease in cell survival. It is concluded that UVB has a clastogenic and cytotoxic effect on PBL. 相似文献
108.
Feldsine PT Lienau AH Leung SC Mui LA Humbert F Bohnert M Mooijman K Schulten S Veld Pi Rollier P Leuschner R Capps K 《Journal of AOAC International》2003,86(2):275-295
Three food types were analyzed for the presence of Salmonella by the AOAC culture method and by the International Organization for Standardization (ISO 6579:2002) culture method. Paired test portions of each food type were simultaneously analyzed by both methods. A total of 21 laboratories representing federal government agencies and private industry, in the United States and Europe, participated in this interlaboratory study. Foods were artificially contaminated with Salmonella and competing microflora if naturally contaminated sources were not available. No statistical differences (p < 0.05) were observed between the AOAC and ISO culture methods for fresh cheese and dried egg products. A statistically significant difference was observed for one of the 2 lots of poultry from the first trial. The poultry meat used in this run was radiation sterilized, artificially contaminated with Salmonella and competitive flora, and then lyophilized. A second trial was conducted with 2 separate lots of raw ground chicken that were naturally contaminated. The results from the second trial showed no statistical difference between the 2 culture methods. A third trial involving 4 laboratories was conducted on 2 separate lots of naturally contaminated raw poultry. Again, no statistically significant differences occurred. It is recommended that ISO 6579:2002 culture method for Salmonella be adopted Official First Action for the analysis of fresh cheese, fresh chilled and frozen poultry, and dried egg products. 相似文献
109.
110.
Franz A. Mautner Florian Bierbaumer Ramon Vicente Saskia Speed nnia Tubau Merc Font-Bardía Roland C. Fischer Salah S. Massoud 《Molecules (Basel, Switzerland)》2022,27(3)
A new series of mononuclear Ho3+ complexes derived from the β-diketonate anions: 4,4,4-trifluoro-1-phenyl-1,3-butanedioneate (btfa−) and 4,4,4-trifuoro-1-(naphthalen-2-yl)-1,3-butanedionate (ntfa−) have been synthesized, [Ho(btfa)3(H2O)2] (1a), [Ho(ntfa)3(MeOH)2] (1b), (1), [Ho(btfa)3(phen)] (2), [Ho(btfa)3(bipy)] (3), [Ho(btfa)3(di-tbubipy)] (4), [Ho(ntfa)3(Me2bipy)] (5), and [Ho(ntfa)3(bipy)] (6), where phen is 1,10-phenantroline, bipy is 2,2′-bipyridyl, di-tbubipy is 4,4′-di-tert-butyl-2,2′-bipyridyl, and Me2bipy is 4,4′-dimethyl-2,2′-bipyridyl. These compounds have been characterized by elemental microanalysis and infrared spectroscopy as well as single-crystal X-ray difraction for 2–6. The central Ho3+ ions in these compounds display coordination number 8. The luminescence-emission properties of the pyridyl adducts 2–6 display a strong characteristic band in the visible region at 661 nm and a series of bands in the NIR region (excitation wavelengths (λex) of 367 nm for 2–4 and 380 nm for 5 and 6). The magnetic properties of the complexes revealed magnetically uncoupled Ho3+ compounds with no field-induced, single-molecule magnet (SMMs). 相似文献