全文获取类型
收费全文 | 517篇 |
免费 | 46篇 |
出版年
2023年 | 6篇 |
2022年 | 5篇 |
2021年 | 11篇 |
2020年 | 6篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 7篇 |
2016年 | 8篇 |
2015年 | 17篇 |
2014年 | 16篇 |
2013年 | 23篇 |
2012年 | 26篇 |
2011年 | 34篇 |
2010年 | 16篇 |
2009年 | 15篇 |
2008年 | 32篇 |
2007年 | 21篇 |
2006年 | 26篇 |
2005年 | 17篇 |
2004年 | 14篇 |
2003年 | 18篇 |
2002年 | 13篇 |
2001年 | 11篇 |
2000年 | 13篇 |
1999年 | 14篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 6篇 |
1995年 | 12篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 13篇 |
1989年 | 6篇 |
1988年 | 13篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 5篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1979年 | 4篇 |
1977年 | 3篇 |
1976年 | 9篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1972年 | 5篇 |
1970年 | 3篇 |
排序方式: 共有563条查询结果,搜索用时 15 毫秒
511.
512.
Structural characterization of novel inositol phosphosphingolipids of Tritrichomonas foetus and Trichomonas vaginalis 总被引:1,自引:0,他引:1
Costello Catherine E.; Glushka John; van Halbeek Herman; Singh Bibhuti N. 《Glycobiology》1993,3(3):261-269
Two major ethanolamine phosphate-substituted inositol phosphosphingolipidshave been identified in the unsaponifiable acidic lipid fractionsof Tritrichomonas foetus and Trichomonas vaginalis. The compoundswere radiolabelled and purified by high-performance thin-layerchromatography followed by high-performance liquid chromatography.The structures were determined by a combination of tandem massspectrometry (MS/MS) and nuclear magnetic resonance (NMR) experiments,and gasliquid chromatography of components obtained bydegradation and derivatization. Inositol in the T.foetus componentwas 1-linked to the phosphosphingolipid, had the phospho-ethanolaminegroup at the 3-position and a fucosyl residue at the 4-position.The T.vaginalis component lacked the fucosyl moiety. Both organismsalso produced inositol phosphosphingolipids having the samelong-chain base (sphingosine or dihydrosphingosine) and thesame fatty acyl distribution as the inositol diphosphate compounds.These glycosphingolipids may represent metabolic intermediatesfor new types of membrane anchors for surface glycopeptidesor glycolipids that mediate the hostparasite relationshipof these trichomonads. The MS/MS and NMR spectroscopic datashould provide reference information for structural determinationsof other phosphorylated inositol derivatives. inositol phosphosphingolipids NMR tandem MS T.foetus T. vaginalis 相似文献
513.
Consistent individual differences in long-term dominance are a basic underlying assumption of hypotheses linking dominance and reproductive success. Long-term and temporary dominance of a colony group of stumptailed macaques was studied for 20 years. There were two variously constituted groups for the first 4 years and a single group for the last 16. Stumptails displayed the matrilineal dominance organization found for several other cercopithecine species. A method was devised to standardize ranks so they could be compared over the years across groups of varying size and composition. No animal maintained the same dominance rank over the entire period of the research or over the last 16 years, but there was considerable consistency over long periods. Although occupants of the male and female alpha positions changed several times, one female was dominant for 18 of the 20 years. She was dominant in 1968, at the start of the study, and at its end in 1988 at which time her 18-year-old son was the dominant male. Variation in dominance ranks was greatest among members of mid-ranking matrilines and least for the lowest ranking. The same female or her son were the lowest ranking animals of their groups in all samples taken over the entire 20 years. 相似文献
514.
Identification of differentially expressed mRNAs in human fetal liver across gestation. 总被引:2,自引:0,他引:2
515.
516.
An economic model which incorporates the major costs associated with the operation of an industrial anaerobic reactor was developed. This model was then used to optimise the operation of a two-stage anaerobic treatment plant through manipulation of the acidification tank pH and recycle flowrate. The most effective operating strategy was to maximise the recycle flowrate and to then optimise the acidification tank pH. For this particular case study it was found that by reducing the acidification tank pH from 6.0 to 5.9 the consumption of caustic was reduced by 10 percent. Furthermore, by increasing the recycle flowrate from 72.7 to 100 m3/h the total cost of operation was reduced by 62 percent. This investigation highlights the need to develop more effective control strategies for the two-stage process and to consider the operational optimisation of the process at the design stage so as to maximise the possible savings that can be made when treating organic wastes. 相似文献
517.
518.
Growth rate and average cell volume were measured throughoutauxospore formation in two populations of Thalassiosira weissflogii(Hustedt). In both cases, the entire population shifted fromrelatively small (800 µm3) to large cells (2800 µm3)over a 5 day interval. This shift was accompanied by a dramaticincrease in the average growth rate of the populations from1.6 to 3.4 doublings/day. 相似文献
519.
520.