全文获取类型
收费全文 | 3033篇 |
免费 | 359篇 |
国内免费 | 2篇 |
出版年
2022年 | 21篇 |
2021年 | 44篇 |
2020年 | 27篇 |
2019年 | 31篇 |
2018年 | 40篇 |
2017年 | 35篇 |
2016年 | 47篇 |
2015年 | 105篇 |
2014年 | 97篇 |
2013年 | 156篇 |
2012年 | 170篇 |
2011年 | 159篇 |
2010年 | 96篇 |
2009年 | 93篇 |
2008年 | 152篇 |
2007年 | 118篇 |
2006年 | 116篇 |
2005年 | 107篇 |
2004年 | 135篇 |
2003年 | 117篇 |
2002年 | 107篇 |
2001年 | 68篇 |
2000年 | 89篇 |
1999年 | 66篇 |
1998年 | 43篇 |
1997年 | 30篇 |
1996年 | 36篇 |
1995年 | 31篇 |
1994年 | 38篇 |
1993年 | 29篇 |
1992年 | 51篇 |
1991年 | 48篇 |
1990年 | 94篇 |
1989年 | 81篇 |
1988年 | 63篇 |
1987年 | 46篇 |
1986年 | 42篇 |
1985年 | 36篇 |
1984年 | 34篇 |
1983年 | 26篇 |
1982年 | 30篇 |
1981年 | 29篇 |
1980年 | 20篇 |
1979年 | 32篇 |
1978年 | 22篇 |
1975年 | 31篇 |
1974年 | 26篇 |
1973年 | 27篇 |
1972年 | 25篇 |
1971年 | 24篇 |
排序方式: 共有3394条查询结果,搜索用时 15 毫秒
21.
Determination of amino acids by reversed-phase chromatography of the adduct with orthophthalaldehyde and a thiol is rapid and sensitive. The major recognized adverse feature of this method is the instability of the reaction product, which requires precise control of reaction timing and chromatographic parameters for reliable quantitative application. We report another source of major variability: reagent instability. Deterioration of reagent was noted as low peak heights and peak broadening and was predictable if the premixed reagent was left at room temperature. Restoration of sharp chromatograms was accomplished by addition of mercaptoethanol or sodium metabisulfite. Reagent which was chromatographically inert contained minimal free thiol by direct assay. Free thiol disappearance was markedly slowed by addition of a chelating agent. Excess mercaptoethanol was deleterious. We conclude that reagent deterioration represents oxidation of the thiol, may be reversed by rereduction with minimal thiol or bisulfite, and may be minimized by inclusion of a metal chelator in the reagent. 相似文献
22.
23.
Many rotifer species live in close association with plants or other animals. Most of these associations are of a commensal or synoecious nature, some rotifer species having lost the ability to live independently. Few rotifers are true parasites, actually harming their hosts.The Seisonidae, Monogononta and Bdelloidea include epizoic and parasitic species. The most widely known are probably the parasites of colonial and filamentous algae (e.g. Volvox, Vaucheria). However, rotifers are also found on a wide range of invertebrates: colonial, sessile Protozoa; Porifera; Rotifera; Annelida; Bryozoa; Echinodermata; Mollusca, especially on the shells and egg masses of aquatic gastropods; Crustacea, including the lower forms (e.g. Daphnia, Asellus, Gammarus) and in the gill chambers of Astacus and Chasmagnathus; the aquatic larvae of insects. There appear to be few records of epizoic or parasitic rotifers among vertebrates, apart from Encentrum kozminskii on carp, Limnias ceratophylli on the Amazonian crocodile, Melanosuchus niger, and an unidentified Bdelloid apparently living as a pathogenic rotifer in Man. 相似文献
24.
25.
26.
27.
28.
29.
30.
Expression of human sequences related to those of mouse mammary tumor virus. 总被引:6,自引:4,他引:2
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
G C Franklin S Chretien I M Hanson H Rochefort F E May B R Westley 《Journal of virology》1988,62(4):1203-1210