全文获取类型
收费全文 | 1138篇 |
免费 | 48篇 |
出版年
2022年 | 12篇 |
2021年 | 32篇 |
2020年 | 9篇 |
2019年 | 9篇 |
2018年 | 26篇 |
2017年 | 22篇 |
2016年 | 34篇 |
2015年 | 44篇 |
2014年 | 53篇 |
2013年 | 84篇 |
2012年 | 81篇 |
2011年 | 74篇 |
2010年 | 40篇 |
2009年 | 31篇 |
2008年 | 46篇 |
2007年 | 43篇 |
2006年 | 52篇 |
2005年 | 33篇 |
2004年 | 40篇 |
2003年 | 30篇 |
2002年 | 14篇 |
2001年 | 17篇 |
2000年 | 22篇 |
1999年 | 21篇 |
1997年 | 10篇 |
1996年 | 7篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 16篇 |
1991年 | 14篇 |
1990年 | 17篇 |
1989年 | 21篇 |
1988年 | 21篇 |
1987年 | 19篇 |
1986年 | 12篇 |
1985年 | 15篇 |
1984年 | 17篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 18篇 |
1978年 | 7篇 |
1976年 | 12篇 |
1975年 | 5篇 |
1974年 | 5篇 |
1973年 | 10篇 |
1972年 | 14篇 |
1971年 | 5篇 |
1970年 | 6篇 |
排序方式: 共有1186条查询结果,搜索用时 171 毫秒
991.
Interactions of saturated, n-6 and n-3 polyunsaturated fatty acids to modulate arachidonic acid metabolism 总被引:6,自引:0,他引:6
Anti-thrombotic effects of omega-3 (n-3) fatty acids are believed to be due to their ability to reduce arachidonic acid levels. Therefore, weanling rats were fed n-3 acids in the form of linseed oil (18:3n-3) or fish oil (containing 20:5n-3 and 22:6n-3) in diets containing high levels of either saturated fatty acids (hydrogenated beef tallow) or high levels of linoleic acid (safflower oil) for 4 weeks. The effect of diet on the rate-limiting enzyme of arachidonic acid biosynthesis (delta 6-desaturase) and on the lipid composition of hepatic microsomal membrane was determined. Both linseed oil- or fish oil-containing diets inhibited conversion of linoleic acid to gamma-linolenic acid. Inhibition was greater with fish oil than with linseed oil, only when fed with saturated fat. delta 6-Desaturase activity was not affected when n-3 fatty acids were fed with high levels of n-6 fatty acids. Arachidonic acid content of serum lipids and hepatic microsomal phospholipids was lower when n-3 fatty acids were fed in combination with beef tallow but not when fed with safflower oil. Similarly, n-3 fatty acids (18:3n-3, 20:5n-3, 22:5n-3, and 22:6n-3) accumulated to a greater extent when n-3 fatty acids were fed with beef tallow than with safflower oil. These observations indicate that the efficacy of n-3 fatty acids in reducing arachidonic acid level is dependent on the linoleic acid to saturated fatty acid ratio of the diet consumed. 相似文献
992.
993.
Garg HG Mrabat H Yu L Freeman C Li B Zhang F Linhardt RJ Hales CA 《Carbohydrate research》2008,343(14):2406-2410
Heparin inhibits the growth of several cell types in vitro, including bovine pulmonary artery smooth muscle cells (BPASMCs). To understand more about the heparin structure required for endogenous activity, chemically modified derivatives of native heparin and glycol-split heparin, namely, 2-O-desulfonated iduronic/glucuronic acid residues in heparin, and 2-O-desulfonated iduronic residues in glycol-split heparin were prepared. These were assayed for their antiproliferative potency on cultured BPASMCs. All of the 2-O-desulfonated heparin derivatives had significantly decreased less antiproliferative activity on BPASMCs. These results suggest that the 2-O-sulfo group of iduronic acid residues in heparin's major sequence is essential for the antiproliferative properties of heparin. The size of heparin does not affect the growth-inhibitory properties of heparin on BPASMCs at the three dose levels examined. 相似文献
994.
Gary Guishan Xiao Meena Garg Shu Lim Derek Wong Vay Liang Go Wai-Nang Paul Lee 《Journal of applied physiology》2008,104(3):828-836
This paper describes a method of determining protein synthesis and turnover using in vivo labeling of protein with deuterated water and analysis of matrix-assisted laser desorption time-of-flight mass spectrometer (MALDI-TOF) spectrum. Protein synthesis is calculated using mass isotopomer distribution analysis instead of precursor to product amino acid enrichment ratio. During protein synthesis, the incorporation of deuterium from water changes the mass isotopomer distribution (isotope envelop) according to the number of deuterium atoms (0, 1, 2, 3, etc.) incorporated, and the distribution of the protein with 0, 1, 2, 3,... atoms of deuterium follows a binomial distribution. A mathematical algorithm by which the distribution of deuterium isotopomers can be extracted from the observed MALDI-TOF spectrum is presented. Since deuterium isotopomers are unique to newly synthesized proteins, the quantitation of their distribution provides a method for the quantitation of newly synthesized proteins. The combined use of postsource decay sequence identification and mass isotopomer distribution analysis makes the use of in vivo labeling with deuterated water a precise method to determine specific protein synthesis. 相似文献
995.
Many physiological and biochemical plant processes affected by salt stress trigger premature nodule senescence and decrease
their ability to fix nitrogen. The objective of this study was to evaluate the role of arbuscular mycorrhiza (AM) in moderating
salt-induced premature nodule senescence in Cajanus cajan (L.) Millsp. Greenhouse experiments were conducted in which the plants were exposed to salinity stress of 4, 6, and 8 dSm−1. Various parameters linked to nodule senescence were assessed at 80 days after sowing. Nodulation, leghemoglobin content,
and nitrogenase enzyme activity measured as acetylene-reducing activity (ARA) were evaluated. Two groups of antioxidant enzymes
were studied: (1) enzymes involved in the detoxification of O2− radicals and H2O2, namely, superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX), and (2) enzymes that are important components of
the ascorbate glutathione pathway responsible for the removal of H2O2, namely, glutathione reductase (GR) and ascorbate peroxidase (APOX). Exposure of plants to salinity stress enhanced nodule
formation; however, nodule growth suffered remarkably and a marked decline in nodule biomass, relative permeability, and lipid
peroxidation was observed. Leghemoglobin content and ARA were reduced under saline conditions. AM significantly improved nodulation,
leghemoglobin content, and nitrogenase activity under salt stress. Activities of SOD, CAT, APOX, POX, and GR increased markedly
in mycorrhizal-stressed plants. A synthesis of the evidence obtained in this study suggests a correlation between enhanced
levels of antioxidant enzyme activities, reduced membrane permeability, reduced lipid peroxidation, and improved nitrogen-fixing
efficiency of AM plants under stressed and unstressed conditions. These factors could be responsible for the protective effects
of mycorrhiza against stress-induced premature nodule senescence. 相似文献
996.
Feasibility of utilization of horse dung spiked filter cake in vermicomposters using exotic earthworm Eisenia foetida 总被引:2,自引:0,他引:2
This contribution reports the potential of vermicomposting technology in the management of horse dung (HD) spiked sugar mill filter cake (SMFC) using an epigeic earthworm Eisenia foetida under laboratory conditions. A total of six vermicomposters filled with different ratios of HD and SMFC were maintained for this study. The growth and fecundity of E. foetida was monitored for 12 weeks. Maximum growth was recorded in 90% HD+10% SMFC feed mixture containing vermicomposter. Earthworms' biomass gain and reproduction was favorably up to 50% HD+50% SMFC feed composition. Maximum cocoons were also recorded in 90% HD+10% SMFC feed mixtures, however increasing proportions of SMFC in different vermicomposters affected the growth and fecundity of worms. A significant decrease in C:N ratio and increase in total kjeldahl nitrogen, total available phosphorus and calcium contents was recorded. The heavy metals content was higher in the vermicompost obtained in all the reactors than initial feed substrates. Based on investigations it is concluded that vermicomposting could be an alternative technology for the management of filter cake if it is mixed in 1:1 ratio with horse dung. 相似文献
997.
998.
999.
Reverse micellar extraction of papain with cationic detergent based system: An optimization approach
Ashish Prabhu A. Sushma Chityala Yachna Garg 《Preparative biochemistry & biotechnology》2017,47(3):236-244
In this study, reverse micellar extraction of papain model system was performed using cetyltrimethylammonium bromide (CTAB)/iso-octane/hexanol/butanol system to optimize the forward and back extraction efficiency (BEE). A maximum forward extraction efficiency of 55.0, 61.0, and 54% was achieved with an aqueous phase pH of 11.0, 150?mM CTAB/iso-octane and 0.1?M NaCl, respectively. Taguchi’s orthogonal array was applied to optimize the pH of stripping phase, concentration of isopropyl alcohol (IPA) and potassium chloride (KCl) for maximizing BEE. The optimal levels of stripping phase pH, concentration of IPA and KCl were found to be 6, 20% (v/v), and 0.8?M, respectively. Under these optimal levels, the BEE was found to be 88% after which enzyme activity was recovered with 2.5-fold purification. Further optimization was performed using artificial neural network-linked genetic algorithm, where the BEE was improved to 90.52% with pH 6, IPA (%)?=?19.938, and KCl (M)?=?0.729. 相似文献
1000.
A comprehensive draft genome sequence for lupin (Lupinus angustifolius), an emerging health food: insights into plant–microbe interactions and legume evolution
下载免费PDF全文
![点击此处可从《Plant biotechnology journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Matthew N. Nelson Gagan Garg Craig A. Atkins Philipp E. Bayer Armando Bravo Scott Bringans Steven Cannon David Edwards Rhonda Foley Ling‐ling Gao Maria J. Harrison Wei Huang Bhavna Hurgobin Sean Li Cheng‐Wu Liu Annette McGrath Grant Morahan Jeremy Murray James Weller Jianbo Jian Karam B. Singh 《Plant biotechnology journal》2017,15(3):318-330
Lupins are important grain legume crops that form a critical part of sustainable farming systems, reducing fertilizer use and providing disease breaks. It has a basal phylogenetic position relative to other crop and model legumes and a high speciation rate. Narrow‐leafed lupin (NLL; Lupinus angustifolius L.) is gaining popularity as a health food, which is high in protein and dietary fibre but low in starch and gluten‐free. We report the draft genome assembly (609 Mb) of NLL cultivar Tanjil, which has captured >98% of the gene content, sequences of additional lines and a dense genetic map. Lupins are unique among legumes and differ from most other land plants in that they do not form mycorrhizal associations. Remarkably, we find that NLL has lost all mycorrhiza‐specific genes, but has retained genes commonly required for mycorrhization and nodulation. In addition, the genome also provided candidate genes for key disease resistance and domestication traits. We also find evidence of a whole‐genome triplication at around 25 million years ago in the genistoid lineage leading to Lupinus. Our results will support detailed studies of legume evolution and accelerate lupin breeding programmes. 相似文献