全文获取类型
收费全文 | 1652562篇 |
免费 | 157404篇 |
国内免费 | 1565篇 |
出版年
2021年 | 18224篇 |
2019年 | 16307篇 |
2018年 | 19493篇 |
2017年 | 18271篇 |
2016年 | 29542篇 |
2015年 | 43461篇 |
2014年 | 51541篇 |
2013年 | 77979篇 |
2012年 | 46596篇 |
2011年 | 37414篇 |
2010年 | 47383篇 |
2009年 | 47643篇 |
2008年 | 34322篇 |
2007年 | 33142篇 |
2006年 | 36238篇 |
2005年 | 37135篇 |
2004年 | 36209篇 |
2003年 | 33354篇 |
2002年 | 31387篇 |
2001年 | 54022篇 |
2000年 | 51810篇 |
1999年 | 46600篇 |
1998年 | 27819篇 |
1997年 | 27779篇 |
1996年 | 26747篇 |
1995年 | 24915篇 |
1994年 | 24602篇 |
1993年 | 23914篇 |
1992年 | 39200篇 |
1991年 | 37223篇 |
1990年 | 35884篇 |
1989年 | 36187篇 |
1988年 | 33209篇 |
1987年 | 31396篇 |
1986年 | 29682篇 |
1985年 | 31159篇 |
1984年 | 28849篇 |
1983年 | 25277篇 |
1982年 | 23574篇 |
1981年 | 22313篇 |
1980年 | 21062篇 |
1979年 | 25066篇 |
1978年 | 22223篇 |
1977年 | 20971篇 |
1976年 | 19732篇 |
1975年 | 19909篇 |
1974年 | 20739篇 |
1973年 | 20951篇 |
1972年 | 18171篇 |
1971年 | 16443篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
971.
The hippocampus and behavioral maturation 总被引:3,自引:0,他引:3
972.
The leakage and destruction of CoA in isolated mitochondria 总被引:1,自引:0,他引:1
973.
Interaction between cytotoxin of the Central Asia cobra venom and dimiristoylphosphatidylcholine bilayer depending on its phase state was studied by ESR with spin label. A conclusion can be drawn that the efficiency of cytotoxin effect on the membranes depends on their phase state. Cytotoxin molecules are incorporated into myophile region of the bilayer, only if the latter is in the liquid crystal state. The interaction between cytotoxins and lipids of the bilayer in a gel state is in the main conditioned by electrostatic forces. 相似文献
974.
Evidence has been presented for the formation of an intermediate compound in the metabolism of 3-hydroxyanthranilic acid to quinolinic acid by 3-hydroxyanthranilase from rat liver preparations. The production of the intermediate was demonstrated by spectrophotometric analyses and quinolinic acid measurements of incubation mixtures in which small amounts of acetone powder extracts of rat liver were used as the enzyme source. The calculated extinction coefficient of the compound was more than double that of the substrate or of the final product, quinolinic acid.The intermediate was shown to be an oxidation product of 3-hydroxyanthranilate as indicated by Thunberg experiments. The data obtained indicate that the intermediate may be a quinone-type compound. 相似文献
975.
W P Hempfling 《Biochimica et biophysica acta》1970,205(2):169-182
976.
VICTOR G. BRUCE 《The Journal of eukaryotic microbiology》1970,17(2):328-334
SYNOPSIS. Chlamydomonas reinhardi has a biological clock regulating phototaxis in dividing and non-dividing cultures; it also can exert some control on growth of continuous cultures. The period length is ∼ 24 hr; it is temperature-compensated and not dependent on the average growth rate. The rhythm can be entrained or phased by light-dark conditions. In dividing cultures a periodic fluctuation in cell number and total protein persists in continuous light. 相似文献
977.
978.
979.
980.
Summary The iliofibularis muscle ofXenopus laevis is reported to contain five types of fibres which have different force—velocity relationships. Ten fibres of each type were selected on the basis of succinate dehydrogenase activity, cross-sectional area and location in the muscle, in order to assess the validity of the fibre type classification.Maximum calcium-stimulated myofibrillar ATPase activity (V
max) and apparent Michaelis constant (K
m) for ATP were determined for these 50 fibres from serial sections. The values obtained varied according to the type of fibre. Type 1 had the highest and type 5 the lowest values forK
m andV
max.In a separate experiment, single freeze-dried fibres were used to determine the relationship between their ATP content and apparentK
m for ATP. There was a tendency for high ATP concentrations in fibres with highK
m values.When myofibrillar ATPase activity was related to the maximum velocity of shortening of the five fibre types, a significant correlation was found. It is concluded that calcium-stimulated myofibrillar ATPase histochemistry allows an estimate of the maximum shortening velocity of muscle fibres fromXenopus laevis. 相似文献