首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   437篇
  免费   15篇
  2022年   10篇
  2021年   8篇
  2020年   3篇
  2019年   8篇
  2018年   11篇
  2017年   10篇
  2016年   10篇
  2015年   22篇
  2014年   30篇
  2013年   22篇
  2012年   17篇
  2011年   23篇
  2010年   16篇
  2009年   12篇
  2008年   12篇
  2007年   18篇
  2006年   12篇
  2005年   12篇
  2004年   17篇
  2003年   14篇
  2002年   9篇
  2001年   8篇
  2000年   12篇
  1996年   3篇
  1995年   3篇
  1994年   4篇
  1992年   12篇
  1991年   3篇
  1990年   4篇
  1989年   5篇
  1988年   12篇
  1987年   10篇
  1986年   2篇
  1985年   5篇
  1984年   5篇
  1983年   5篇
  1982年   4篇
  1981年   2篇
  1980年   3篇
  1979年   8篇
  1978年   4篇
  1977年   6篇
  1975年   6篇
  1974年   6篇
  1973年   4篇
  1972年   2篇
  1971年   5篇
  1970年   2篇
  1969年   2篇
  1967年   2篇
排序方式: 共有452条查询结果,搜索用时 15 毫秒
101.
The lipid composition of tomato fruit and its mitochondrial fraction were examined at various stages of fruit ripeness. Phosphatidyl choline, phosphatidyl ethanolamine, monogalactosyl diglyceride, digalactosyl diglyceride and phosphatidyl inositol were found to be the major lipids of tomato pericarp at all stages of ripeness. Mitochondrial lipids resembled those of the parent tissue except for the absence of monogalactosyl diglyceride and a greater percentage of diphosphatidyl glycerol and phosphatidic acid. Changes in the lipid-protein ratio of mitochondria were noted with ripening.  相似文献   
102.
The seasonal distribution of Aeromonas hydrophila in water and recovery rate from live river fish was investigated. The highest isolation rates of A. hydrophila occurred in water during the late winter followed by a progressive decline in density during the summer and monsoon seasons. The organism was recovered from fish throughout the period from which it was concluded that they form a reservoir which is unrelated to their density in water. The enterotoxigenicity of some environmental strains was tested in suckling mice and rabbit ileal loop.  相似文献   
103.
104.
This paper presents a novel voxel-based method for texture analysis of brain images. Texture analysis is a powerful quantitative approach for analyzing voxel intensities and their interrelationships, but has been thus far limited to analyzing regions of interest. The proposed method provides a 3D statistical map comparing texture features on a voxel-by-voxel basis. The validity of the method was examined on artificially generated effects as well as on real MRI data in Alzheimer''s Disease (AD). The artificially generated effects included hyperintense and hypointense signals added to T1-weighted brain MRIs from 30 healthy subjects. The AD dataset included 30 patients with AD and 30 age/sex matched healthy control subjects. The proposed method detected artificial effects with high accuracy and revealed statistically significant differences between the AD and control groups. This paper extends the usage of texture analysis beyond the current region of interest analysis to voxel-by-voxel 3D statistical mapping and provides a hypothesis-free analysis tool to study cerebral pathology in neurological diseases.  相似文献   
105.
106.
107.
108.
Ellipticine compounds, derivatives of pyrido-(4-3b) carbazole are used in the human cancer therapy. Most of these drugs interact directly with DNA molecule. CNDO method, alongwith second order perturbation theory and multicentered-multipole approxiation have been used to compute intermolecular interaction energies of ellipticine with DNA ase pairs (GC and AT) in both normal and inverted cases. An attempt has been made to correlate the drug-nucleic acid interactions for ellipticine to locate site of drug action and binding pattern on the basis of intermolecular forces  相似文献   
109.
A procedure has been devised for isolating tightly coupled mitochondria from the intima-media strip of pig aorta. The mitochondria exhibit respiratory control with succinate, pyruvate-malate, β-hydroxybutyrate or α-glycerol phosphate as substrate. Furthermore, submitochondrial particles from these preparations exhibit an energy-dependent reduction of NADP+ by NADH.  相似文献   
110.
The phospholipid composition of the electron transport particles and coupling factor-depleted electron transport particles of Mycobacterium phlei are the same, but they differ in contents. The accessibility of partially purified phospholipase A to these membrane phospholipids was found to be different. Treatment of membranes of Mycobacterium phlei with phospholipase A impairs the rate of oxidation as well as phosphorylation. The inhibition of phosphorylation can be reversed by washing the membranes with defatted bovine serum albumin. The reconstitution of membrane-bound coupling factor-latent ATPase activity to phospholipase A-treated depleted electron transport particles and their capacity to couple phosphorylation to oxidation of substrates remained unaffected after phospholipase A treatment. However, the pH gradient as measured by bromthymol blue was not restored after reconstitution of phospholipase A-treated depleted electron transport particles with membrane-bound coupling factor-latent ATPase. These findings show that the phosphorylation coupled to the oxidation of substrates can take place without a pronounced pH gradient in these membrane vesicles. The dye 1-anilino-8-naphthalene sulfonic acid (ANS) exhibited low levels of energized and nonenergized fluorescence in phospholipase A-treated membranes. This decrease in the level of ANS fluorescence in phospholipase A-treated membranes was found to be directly related to the amount of phospholipids cleaved. The decrease in the energy-dependent ANS response in phospholipase A-treated electron transport particles, as compared with untreated electron transport particles, was shown to be a result of a change in the apparent K-d of the dye-membrane complex, and of a decrease in the number of irreversible or slowly reversible binding sites, with no change in the relative quantum efficiency of the dye. The decrease in ANS fluorescence in phospholipase A-treated particles appears to be due to a decrease in the hydrophobicity of the membranes.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号