全文获取类型
收费全文 | 190篇 |
免费 | 3篇 |
专业分类
193篇 |
出版年
2013年 | 5篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 5篇 |
2009年 | 4篇 |
2008年 | 7篇 |
2007年 | 10篇 |
2006年 | 8篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2000年 | 2篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 7篇 |
1993年 | 2篇 |
1991年 | 3篇 |
1990年 | 7篇 |
1988年 | 2篇 |
1986年 | 4篇 |
1983年 | 3篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1973年 | 5篇 |
1972年 | 9篇 |
1971年 | 10篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1967年 | 2篇 |
1965年 | 2篇 |
1961年 | 2篇 |
1960年 | 2篇 |
1959年 | 5篇 |
1955年 | 3篇 |
1943年 | 1篇 |
1941年 | 1篇 |
1938年 | 1篇 |
1937年 | 2篇 |
1936年 | 1篇 |
1935年 | 1篇 |
1934年 | 2篇 |
1932年 | 2篇 |
1928年 | 1篇 |
1927年 | 3篇 |
1926年 | 1篇 |
1924年 | 1篇 |
1922年 | 1篇 |
1917年 | 2篇 |
排序方式: 共有193条查询结果,搜索用时 0 毫秒
21.
Diurnal, rhythmic variation of melatonin content in the pinealgland, blood serum, and brain have been found in chickens, withgreater amounts present in all tissues during nighttime thanduring daytime. Similar daily rhythms appear to occur in thepineal gland and serum of rats and in the serum and urine ofhumans. It is proposed that these correlated fluctuations inmelatonin levels are causally related, elevated pineal contentresulting in increased melatonin content of the blood and increasedaccumulation by the brain. The brain of chickens, especiallythe hypothalamus, appears to accumulate melatonin and is probablya primary site of action of melatonin. 相似文献
22.
23.
Risk-sensitive behavior is the phenomenon of animals exhibitingpreferences when offered choices whose outcomes differ in theirdegree of variance. It is now well demonstrated that many animalsare sensitive to differences in the magnitude of variance inrewards. A considerable body of literature on risk sensitivityhas been generated in recent years, encompassing theoreticaland empirical work, from both functional and mechanistic approaches.Nevertheless, it is less than clear how animal preferences forvariability are determined. It is therefore timely to look broadlyat what has been accomplished, and to identify the most promisingsynthetic approaches for future work. 相似文献
24.
Feces from a specimen of Tamandua tetradactyla (Linn.) from Portel, Para State, north Brazil, contained two different coccidial oocysts; one identified as Eimeria tamanduae Lainson 1968, and the other as a new species, described here as Eimeria corticulata n. sp. Oocysts of E. corticulata are ellipsoidal, 37.4 × 30.4 (31.2–43.7 × 23.7–35.0) μm, shape index (length/width) 1.2 (1.0–1.5). Oocyst wall 2.5–3.7 μm thick and composed of two layers; an outer thick, brown-yellow one with radial striations, and a thin inner smooth one: no visible micropyle. Oocyst residuum a large globule of about 10.7 × 10.3 μm, usually accompanied by a number of smaller attached globules. Sporocysts ellipsoidal, 21.0 × 11.0 (20.0–22.5 × 10.0–12.5) μm, with a conspicuous Stieda body: shape index 1.9 (1.6–2.2). Sporocyst residuum a small number of scattered granules: sporozoites 18.7 × 5.0 μm, with a large posterior refractile body. Eimeria zygodontomyis n. sp. is described in feces from Zygodontomys lasiurus (Lund) from the Serra dos Carajas, Para. Oocysts ellipsoidal to cylindrical, 16.5 × 12.0 (13.7–18.7 × 11.2–12.3) μm, shape index 1.4 (1.2–1.5). Wall colorless, smooth, single-layered and about 0.6 μm thick: no micropyle. No oocyst residuum, but a polar granule of about 1.8 × 1.0 μm is sometimes present. Sporocysts ellipsoidal, 8.4 × 5.5(7.5–8.7 × 5.0–6.2) μm, shape index 1.5 (1.4–1.7), with a thin colorless wall and a delicate Stieda body. Sporozoites enclose a compact residuum of about 2.5 × 3.7 μm. 相似文献
25.
HUI LIU GUIJUN YAN FUCHENG SHAN RALPH SEDGLEY 《Botanical journal of the Linnean Society. Linnean Society of London》2006,151(3):387-394
Karyotypes of 27 species in Leucadendron are analysed for the first time. New chromosome counts are reported for 15 species, with 2 n = 26 occurring in all of them. Karyotype analysis indicated that chromosomes of Leucadendron taxa are small in size and have predominantly median to submedian centromeres. The mean sizes of somatic metaphase chromosomes ranged from 1.05 to 2.65 µm. Based on Stebbins' karyotype classification, 1A type was found in L. galpinii , L. muirii , L. orientale , L. platyspermum , L. rubrum , and L. salignum ; 2A type in L. conicum , L. flexuosum , L. laureolum , L. meridianum , L. salicifolium , L. stelligerum , and L. teretifolium ; and 2B type in L. argenteum , L. chamelaea , L. discolor , L. elimense , L. eucalyptifolium , L. floridum , L. gandogeri , L. linifolium , L. loeriense , L. macowanii , L. procerum , L. spissifolium , L. strobilinum , and L. tinctum . These types are the three most symmetrical karyotypes and are considered to be primitive. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 387–394. 相似文献
26.
An omnibus test of normality for moderate and large size samples 总被引:4,自引:0,他引:4
27.
28.
SYNOPSIS. The mechanism of carbohydrate dissimilation was studied in cell-free extracts prepared from mass cultures of the trichomonads. Evidence for the presence of all the enzymes associated with the Embden-Meyerhof glycolytic scheme was obtained. Several enzyme systems directly associated with the glycolytic pathway were examined. Two of these, alcohol dehydrogenase and phosphorylase, were not demonstrated in the T. vaginalis extract. The absence of phosphorylase in the presence of a very high glycogen concentration in the cell (20.8%) suggests the possibility of an alternate route. A very active TPN-linked "malic enzyme" was also demonstrated, although no functional citric acid cycle is known for this trichomonad. Based on the experimental evidence and collateral data, a functional Embden-Meyerhof system was suggested for T. vaginalis. 相似文献
29.
Mechanisms of action of abscisic acid at the cellular level 总被引:9,自引:2,他引:9
30.
RUTH EICHMANN CORNELIA DECHERT KARL-HEINZ KOGEL RALPH HÜCKELHOVEN 《Molecular Plant Pathology》2006,7(6):543-552
BAX Inhibitor-1 (BI-1) is a conserved cell death suppressor protein. In barley, BI-1 ( HvBI-1 ) expression is induced upon powdery mildew infection and when over-expressed in epidermal cells of barley, HvBI-1 induces susceptibility to the biotrophic fungal pathogen Blumeria graminis . We co-expressed mammalian pro-apoptotic BAX together with HvBI-1, and the mammalian BAX antagonist BCL-XL in barley epidermal cells. BAX expression led to cessation of cytoplasmic streaming and collapse of the cytoplasm while co-expression of HvBI-1 and BCL-XL partially or completely, respectively, rescued cells from BAX lethality. When B. graminis was attacking epidermal cells, a green fluorescent protein fusion of HvBI-1 accumulated at the site of attempted penetration and was also present around haustoria. Over-expression of HvBI-1 in epidermal cells weakened a cell-wall-associated local hydrogen peroxide burst in a resistant mlo -mutant genotype and supported haustoria accommodation in race-specifically resistant MLA12 -barley. HvBI-1 is a cell death regulator protein of barley with the potential to suppress host defence reactions. 相似文献