全文获取类型
收费全文 | 278篇 |
免费 | 5篇 |
国内免费 | 5篇 |
专业分类
化学 | 197篇 |
力学 | 10篇 |
数学 | 39篇 |
物理学 | 42篇 |
出版年
2022年 | 3篇 |
2021年 | 2篇 |
2018年 | 4篇 |
2016年 | 9篇 |
2015年 | 4篇 |
2014年 | 6篇 |
2013年 | 21篇 |
2012年 | 20篇 |
2011年 | 13篇 |
2010年 | 8篇 |
2009年 | 4篇 |
2008年 | 15篇 |
2007年 | 18篇 |
2006年 | 14篇 |
2005年 | 13篇 |
2004年 | 8篇 |
2003年 | 20篇 |
2002年 | 12篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1987年 | 1篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1934年 | 2篇 |
1932年 | 2篇 |
1930年 | 3篇 |
1927年 | 1篇 |
排序方式: 共有288条查询结果,搜索用时 265 毫秒
191.
192.
193.
Park KH Kim JS Lee YR Moon YJ Hur H Choi YH Kim CH Kim UH Song EK Yoo WH Lee CS Kim BS Lee SH Ryu PY Han MK 《Experimental & molecular medicine》2007,39(5):673-678
Lipoprotein plays a role in the host defense against bacterial infection, and its serum level has been demonstrated to be an important prognosis factor of survival. We have previously demonstrated that LDL directly inactivates the hemolytic activity of Vibrio vulnificus cytolysin (VVC) in vitro. The object of this study was therefore to examine whether the LDL-mediated inactivation of VVC leads to protection against lethal infection of V. vulnificus in vivo, using wild and VVC-deficient V. vulnificus strains. Unexpectedly, we found that LDL protects mouse lethality induced by VVC-deficient as well as wild V. vulnificus strain. We also demonstrated that LDL blocks V. vulnificus LPS-induced lethality in mice. These results suggest that LDL preferentially act on endotoxin rather than exotoxin in the protection against V. vulnificus-induced mice lethality. 相似文献
194.
Ketene-forming eliminations from ArCH2CO2C6H3-2-X-4-NO2 (Ar = thienyl, 1) promoted by R2NH/R2NH2+ in 70 mol % MeCN(aq) have been studied kinetically. When X = CF3 and NO2, the reactions exhibit second-order kinetics as well as beta = 0.30-0.64 and |betalg| = 0.31-0.52 that decrease with a better leaving group. Hence, an E2 mechanism is evident. As the leaving group is made poorer (X = H, OCH3, and Cl), E2 transition state becomes more skewed toward the proton transfer, as revealed by the increase in Br?nsted beta to 0.5-0.64, and the E1cb mechanism competes. The changes in the k1 and k-1/k2 values with the reactant structure variation provide additional support for the competing E1cb mechanism. By comparing with existing data for 4-YC6H4CH2CO2C6H3-2-X-4-NO2, the effect of beta-aryl group on ketene-forming elimination is assessed. 相似文献
195.
J. Rae 《Fresenius' Journal of Analytical Chemistry》1930,80(3-4):156
Ohne Zusammenfassung 相似文献
196.
White-light digital image cross-correlation (DICC) analysis of the deformation of composite materials with random microstructure 总被引:1,自引:0,他引:1
P. J. Rae S. J. P. Palmer H. T. Goldrein A. L. Lewis J. E. Field 《Optics and Lasers in Engineering》2004,41(4):635
A sophisticated image cross-correlation algorithm (J. Appl. Opt. 33 (1994) 6667) has been used to measure both components of in-plane displacement at the surface of a deforming composite material. The natural random pattern present on the surface of a polished polymer bonded explosive (PBX) sample is photographed using a high-resolution digital camera mounted on an optical microscope. Frames are taken as the sample deforms and small subimages from each frame are compared with a base-frame recorded before loading. The resulting displacement information reveals the average motion present from the centre of each of the small subimages used in the analysis, relative to the original position. Currently, there is considerable interest in monitoring the safety of PBXs over the medium to long term and in response to accidental stimuli. Knowledge of the ways in which cracks are created and propagate within the material is a key aspect of understanding. Experiment shows that the accuracy of this technique is 0.1 pixels corresponding to 50 nm in the experimental arrangement used. The technique has wide application to many small to medium strain experimental situations due to the ease of data recording. In the experiment presented here, the natural random microstructure of the sample is used to make measurements, however, any manufactured random pattern applied to a sample would enable the method to be successful. 相似文献
197.
198.
199.
200.
Kang MY Lim CS Kim HS Seo EW Kim HM Kwon O Cho BR 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(7):1953-1960
Molecular imaging by two‐photon microscopy (TPM) has become indispensable to the study of biology/medicine owing to its capability of imaging deep inside intact tissues. To make TPM a more‐versatile tool, a large variety of two‐photon probes are needed. Herein, we report a new two‐photon fluorescent probe (ANi2) that can be excited by 750 nm femtosecond pulses and detect Ni2+ ions in fresh fish organs at 90–175 μm depth without interference from the pH value or from other biologically relevant species through the use of TPM. TPM images of fish organs labeled with ANi2 revealed that Ni2+ ions accumulate in fish organs in the order: kidney > heart > gill ≥ liver. Moreover, a linear relationship was found between the two‐photon‐excited fluorescence (TPEF) and the inductively coupled plasma mass spectrometry intensities (ICP‐MS), thereby allowing the quantitative measurement of Ni2+ ions in live tissue. 相似文献