全文获取类型
收费全文 | 310篇 |
免费 | 11篇 |
国内免费 | 10篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 9篇 |
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 12篇 |
2012年 | 12篇 |
2011年 | 13篇 |
2010年 | 7篇 |
2009年 | 14篇 |
2008年 | 9篇 |
2007年 | 19篇 |
2006年 | 10篇 |
2005年 | 16篇 |
2004年 | 9篇 |
2003年 | 6篇 |
2002年 | 13篇 |
2001年 | 19篇 |
2000年 | 10篇 |
1999年 | 15篇 |
1998年 | 11篇 |
1997年 | 12篇 |
1996年 | 11篇 |
1995年 | 5篇 |
1994年 | 15篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有331条查询结果,搜索用时 140 毫秒
141.
Eluned Price Rob Coleman Judith Ahsmann Gale Glendewar Jenna Hunt Tessa Smith Dominic Wormell 《American journal of primatology》2019,81(8)
Pied tamarins (Saguinus bicolor) are endangered New World primates, and in captivity appear to be very susceptible to stress. We measured cortisol in 214 saliva samples from 36 tamarins and in 227 fecal samples from 27 tamarins, and investigated the effects of age, sex, pregnancy, rearing history, social status, weight, group composition, and enclosure type using generalized linear mixed models. There was no effect of age on either fecal or salivary cortisol levels. Female pied tamarins in late pregnancy had higher fecal cortisol levels than those in early pregnancy, or nonpregnant females, but there was no effect of pregnancy on salivary cortisol. Females had higher salivary cortisol levels than males, but there was no effect of rearing history. However, for fecal cortisol, there was an interaction between sex and rearing history. Hand‐reared tamarins overall had higher fecal cortisol levels, but while male parent‐reared tamarins had higher levels than females who were parent‐reared, the reverse was true for hand‐reared individuals. There was a trend towards lower fecal cortisol levels in subordinate individuals, but no effect of status on salivary cortisol. Fecal but not salivary cortisol levels declined with increasing weight. We found little effect of group composition on cortisol levels in either saliva or feces, suggesting that as long as tamarins are housed socially, the nature of the group is of less importance. However, animals in off‐show enclosures had higher salivary and fecal cortisol levels than individuals housed on‐show. We suggest that large on‐show enclosures with permanent access to off‐exhibit areas may compensate for the effects of visitor disturbance, and a larger number of tamarins of the same species housed close together may explain the higher cortisol levels found in tamarins living in off‐show accommodation, but further research is needed. 相似文献
142.
二色补血草试管苗生根及移栽基质研究 总被引:6,自引:0,他引:6
以二色补血草为材料,研究了不同浓度激素配比对试管苗生根量及根长的影响,以及生根苗在不同移栽基质中的成活率和生长状况。结果表明,试管苗在MS+NAA 1.0mg/L培养基中的平均根量最多,在MS+IBA 1.0mg/L培养基中平均根长最长;生根苗在泥炭+珍珠岩(1:1)的基质中生长最好。同时进行降低成本的试验。 相似文献
143.
144.
145.
红凤菜〔Gynura bicolor(Willd.)DC.〕为菊科(Compositae)菊三七属(Gynura Cass.)植物,又名观音苋和补血菜等。红凤菜是传统山野菜,营养丰富,在东亚一些国家(如中国和日本)常用于制作蔬菜沙拉和天麸罗等供食用;而且在中国南方的部分地区还将其作为治疗糖尿病的草药[1]。据记载[2],红凤菜全草可入药,味甘、辛,性凉,具有凉血止血、清热消肿的功效;内服治咳血、血崩、痛经、血气痛、支气管炎、盆腔炎、中暑 相似文献
146.
Tian-Tian Wang Zhi-Jie Ren Zhi-Quan Liu Xue Feng Rui-Qi Guo Bao-Guo Li Le-Gong Li Hai-Chun Jing 《植物学报(英文版)》2014,56(3):315-332
In halophytic plants, the high-affinity potassium transporter HKT gene family can selectively uptake K+ in the presence of toxic concentrations of Na+. This has so far not been well examined in glycophytic crops. Here, we report the characterization of SbHKTI;4, a member of the HKT gene family from Sorghum bicolor. Upon Na+ stress, SbHKT1;4 expression was more strongly upregulated in salt-tolerant sorghum accession, correlating with a better balanced Na+/ K+ ratio and enhanced plant growth. Heterogeneous expression analyses in mutants of Saccharomyces cerevisiae and Arabidopsis thaliana indicated that overexpressing SbHKT1;4 resulted in hypersensitivity to Na+ stress, and such hypersensitivity could be alleviated with the supply of elevated levels of K+, implicating that SbHKT1;4 may mediate K+ uptake in the presence of excessive Na+. Further electrophysiological evidence demonstrated that SbHKT1;4 could transport Na+ and K+ when expressed in Xenopus laevis oocytes. The relevance of the finding that SbHKTI;4 functions to maintain optimal Na+/K+ balance under Na+ stress to the breeding of salt-tolerant glycophytic crops is discussed. 相似文献
147.
Twenty days’ exposure to 50 or 100 mM NaCl in the rooting medium substantially increased fresh and dry weights of seedling
shoots of the recretohalophyte Limonium sinense while 200 or 300 mM were increasingly inhibitory. KCl treatment was only slightly stimulating (50 mM) or strongly inhibitory
(100–300 mM). Lesser effects on leaf area were also seen. Diameter of foliar salt glands was significantly larger than that
of controls in 100 and 200 mM NaCl with the effect being reversed at higher concentrations. Gland enlargement was also observed
in the presence of 100 mM KCl, while larger concentrations reduced gland size. Generally, gland diameter was larger in the
presence of NaCl than in KCl. NaCl and KCl also increased gland number per leaf and secretion rate per gland. At 100 and 200 mM
NaCl or KCl, Na+ secretion per leaf from NaCl-treated plants exceeded K+ secretion rate from KCl-treated plants while at 200 mM, Na+ secretion per gland was significantly higher for Na+ than for K+. Evidence of cell death in leaves of salt-treated plants using Evans blue staining indicates that release of cell contents
through loss of membrane integrity contributed to the secretion values. We conclude that the greater tolerance of L. sinenseto to NaCl compared to KCl is linked to the more effective secretion of Na+ than of K+ and, in turn, to a greater stimulation of salt gland formation and activity and larger gland diameter. 相似文献
148.
P. Basavaraju N.P. Shetty H.S. Shetty E. de Neergaard H.J.L. Jørgensen 《Journal of applied microbiology》2009,107(2):404-415
Aims: To investigate the infection biology of Colletotrichum sublineolum (isolate CP2126) and defence responses in leaves of resistant (SC146), intermediately resistant (SC326) and susceptible (BTx623) sorghum genotypes.
Methods and Results: Infection biology and defence responses were studied quantitatively by light microscopy, H2 O2 accumulation by DAB staining and HRGP accumulation by immunological methods. Inhibition of conidial germination and appressorium formation may represent prepenetration defence responses on the leaf surface. Inducible defence responses in the resistant genotypes included decreases in formation of appressoria as well as accumulation of H2 O2 , HRGPs and phytoalexins. Concomitant with these inducible responses, fungal growth was stopped during or just after penetration in genotypes SC146 and SC326. High levels of H2 O2 accumulating at late infection stages (5 days after inoculation) in the susceptible genotype BTx623 correlated with necrosis and tissue degeneration.
Conclusions: The early accumulation of H2 O2 and HRGPs indicates roles in defence whereas the late accumulation in genotype BTx623 correlated with successful pathogenesis.
Significance and Impact of the Study: The fact that there is a significant correlation between induced accumulation of H2 O2 , papilla formation and cell wall cross-linking, as evidenced by HRGP accumulation, and cessation of pathogen growth in resistant genotypes may help exploit host resistance in sorghum. 相似文献
Methods and Results: Infection biology and defence responses were studied quantitatively by light microscopy, H
Conclusions: The early accumulation of H
Significance and Impact of the Study: The fact that there is a significant correlation between induced accumulation of H
149.
在整理蓝雪科标本时,发现了补血草属的一个新变种:玛多补血草(Lim onium aureumH ill.var.maduoen-sis),生境为海拔4 000 m以上的滩地紫花针茅高寒草原和盐碱化土壤中。 相似文献
150.
四种补血草属植物叶片泌盐结构的扫描电镜观察 总被引:10,自引:1,他引:9
利用扫描电镜技术,对4种补血草属植物大叶补血草(Limonium gmelinii (Willd.) Kuntze)、耳叶补血草(Limoniu otolepis (Schrenk) Kuntze)、繁枝补血草(Limonium myrianthum (Schrenk) Kuntze)和簇枝补血草(Limonium auream)的叶表面进行了研究,以探讨植物微形态结构与生态环境的关系。结果表明,这4种植物的上下表皮都分布有盐腺,且上表皮的盐腺密度大于下表皮,盐腺的基本结构相同,多由20个细胞构成,其中4个分泌细胞顶端的角质层中央有一小孔,植物体靠盐腺的泌盐孔泌盐。但4种植物在盐腺的密度、盐腺的大小、盐腺与周围表皮细胞的位置等方面存在差异。植物在对盐碱生境的长期适应过程中,促使其强烈地分化出泌盐结构,因而,具有明显的生态适应性。 相似文献