全文获取类型
收费全文 | 353篇 |
免费 | 14篇 |
国内免费 | 37篇 |
专业分类
404篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 20篇 |
2013年 | 18篇 |
2012年 | 15篇 |
2011年 | 17篇 |
2010年 | 9篇 |
2009年 | 17篇 |
2008年 | 15篇 |
2007年 | 18篇 |
2006年 | 23篇 |
2005年 | 24篇 |
2004年 | 20篇 |
2003年 | 17篇 |
2002年 | 11篇 |
2001年 | 19篇 |
2000年 | 10篇 |
1999年 | 13篇 |
1998年 | 7篇 |
1997年 | 9篇 |
1996年 | 7篇 |
1995年 | 11篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 13篇 |
1989年 | 3篇 |
1988年 | 7篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 7篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1979年 | 2篇 |
1978年 | 1篇 |
排序方式: 共有404条查询结果,搜索用时 15 毫秒
31.
沙田柚不同外植体离体培养与植株再生的研究 总被引:10,自引:0,他引:10
利用组织培养进行柑桔良种的快速繁殖可以克服常规方法费时的缺点 ,为进一步进行无病原体苗木繁育、诱变育种及遗传转化创造有利条件。目前我国开展此项工作较为广泛 ,已先后在红江橙 [1 ]、柠檬 [2 ]、金柑 [3]、甜橙 [4]及蕉柑 [5]等柑桔类中建立了组织培养的再生体系 ,但在柚类中相关的研究较少。笔者以沙田柚为材料 ,在离体培养条件下 ,成功诱导上下胚轴、根段及子叶的不定芽形成和植株再生。1 材料与方法1 .1 植物材料沙田柚种子 ( Citrus grandis Osbeck cv.Shatian Yu)经表面消毒后黑暗培养无菌苗 ,当苗长至 2 0 d左右时 ,将上… 相似文献
32.
光照对砀山酥梨果实发育过程中POD、PAL、PPO酶活性的影响研究 总被引:6,自引:1,他引:5
以40年生砀山酥梨为材料,用ZD-IA型照度计测定光照强度,用分光光度法测定POD、PAL、PPO等3种酶的活性;研究了光照强度对果实发育过程中POD、PAL、PPO等3种酶活性的影响。结果表明:(1)光照强度对POD、PAL、PPO等3种酶活性有显著的影响;(2)在光照充足的部位,POD、PAL酶活性较高,具体表现为高光强>中光强>弱光强>极弱光强,彼此间活性差异极显著(P<0.01);(3)PPO在光照充分的情况下,活性偏低,表现为高光强<中光强<弱光强<极弱光强,差异显著。 相似文献
33.
The pattern recognition receptor AtRLP23 from Arabidopsis thaliana recognizes the epitopes (nlp24s) of necrosis and ethylene‐inducing peptide 1‐like proteins (NLPs) and triggers pattern‐triggered immunity (PTI). Here, we established methods for studying the early events of PTI in the hybrid poplar cultivar Shanxin (Populus davidiana × Populus bolleana) in response to the flagellin epitope. We confirmed that wild‐type Shanxin cannot generate PTI responses on nlp24 treatment. Four NLP homologues were characterized from two common fungal pathogens of Shanxin, namely Marssonina brunnea f. sp. monogermtubi (MbMo) and Elsinoë australis (Ea), which cause black leaf spot and anthracnose disease, respectively, and the nlp24s of three of them could be responded to by Nicotiana benthamiana leaves expressing AtRLP23. We then created AtRLP23 transgenic Shanxin lines and confirmed that the heterologous expression of AtRLP23 conferred on transgenic Shanxin the ability to respond to one nlp24 of each fungal pathogen. Consistently, infection assays with MbMo or Ea showed obviously lower levels of disease symptoms and significantly inhibited the growth of fungi on the transgenic poplar compared with that in wild‐type poplar. Overall, our results indicated that the heterologous expression of AtRLP23 allowed transgenic Shanxin to generate a PTI response to nlp24s, resulting in increased broad‐spectrum fungal disease resistance. 相似文献
34.
Polar transport of auxin has been identified as a central element of pattern formation. To address the underlying cellular mechanisms, we use the tobacco cell line (Nicotiana tabacum L. cv. Bright Yellow 2; BY-2) as model. We showed previously that cell divisions within a cell file are synchronized by polar auxin flow, linked to the organization of actin filaments (AF) which, in turn, is modified via actin-binding proteins (ABPs). From a preparatory study for disturbed division synchrony in cell lines overexpressing different ABPs, we identified the actin depolymerizing factor 2 (ADF2). A cell line overexpressing GFP-NtADF2 was specifically affected in division synchrony. The cell division pattern could be rescued by addition of Phosphatidylinositol 4,5-bisphosphate (PIP2) or by phalloidin. These observations allow to draw first conclusions on the pathway linking auxin signalling via actin reorganization to synchronized cell division placing the regulation of cortical actin turnover by ADF2 into the focus. 相似文献
35.
L. Vitale C. Arena P. Carillo P. Di Tommasi B. Mesolella F. Nacca 《Plant biosystems》2013,147(2):485-494
Abstract Net ecosystem exchange (NEE), leaf gas exchange and biochemical traits were investigated in an irrigated maize crop grown under Mediterranean conditions. Sub-optimal irrigation water supply determined a drought stress during the early vegetative growth stage (45–49 days after swing) that decreased NEE. Drought, in the late vegetative stage, also caused a reduction of leaf gas exchange. In the latter period, proline, glycine and serine, as well as sucrose leaf contents increased, while starch, proteins and glucose contents decreased. In the early reproductive stage, the crop experienced a longer dry spell that induced a reduction in canopy as well as in leaf gas exchanges, while protein and free amino acid contents decreased with respect to the late vegetative stage. Both ecophysiological and biochemical data demonstrate a good capacity of cultivar Pioneer PR32D99 to endure the environmental stress, related to Mediterranean summer drought, leading to an elevated dry matter yield at harvest. Photosynthetic apparatus appeared fairly resistant to soil water shortage due likely to the increased leaf content of organic solutes, such as amino acids and soluble sugars. 相似文献
36.
NH4 : NO3 nutrition influence on biomass productivity and root respiration of poplar and willow clones
下载免费PDF全文
![点击此处可从《Global Change Biology Bioenergy》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Nitrogen fertilization often improves the yield of intensively managed, short‐rotation coppices. However, information of N nutrition form on the growth of common species and clones used for biomass production is limited. Thus, this study aims at evaluating N form effects on the growth of two Salicaceae clones. Cuttings of the poplar clone Max 4 (Populus maximovizcii × P. nigra) and the willow clone Inger (Salix triandra × S. viminialis) were fertilized in a pot experiment with four ratios of nitrate (NO3?) to ammonium (50%, 62.5%, 75% and 87.5% NO3? balanced with ammonium (NH4+) to constant total N) for one growing season and under stable soil pH. Plants were harvested for analysis of biomass and morphology of leaves, stem and roots. Respiration of fine and coarse roots (RR) was determined and related to biomass growth. Salix cv. Inger accumulated more total dry matter than Populus cv. Max 4. In both Salicaceae clones, the total biomass was significantly influenced by the nitrate ratio and greatest in plants fertilized with 50% NO3? of the total N supply. Both clones possess a different leaf and root morphology, but no significant influence of the NO3? ratio on the morphology was found. Fine RR rates differed significantly between clones, with significantly greater fine RR in Max 4; 87.5% NO3? fertilization increased the fine RR. Fine RR and total accumulated plant biomass were closely related. Our study is the first to show the tremendous influence of fine root respiration, especially including the carbon‐intensive reduction of NO3? to NH4+, on the aboveground growth of Salicaceae clones. Ways to improve yield in SRC are thus to lower the assimilate consumption by fine roots and to match fertilization regimes to the used clones or vice versa. 相似文献
37.
38.
39.
40.
Chaves-Pozo E Pelegrín P García-Castillo J García-Ayala A Mulero V Meseguer J 《Cell and tissue research》2004,316(2):189-195
The fish immune response to Gram-negative bacteria is poorly understood. In this study, we use a monoclonal antibody (mAb) specific to acidophilic granulocytes from the marine fish gilthead seabream (Sparus aurata L.), together with an antiserum specific to interleukin-1cv15j862xf7at6/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"> (IL-1cv15j862xf7at6/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">) from this species, in order to investigate whether these cells are involved in the immune response against the pathogenic bacterium Vibrio anguillarum and, in particular, in the production of the pro-inflammatory cytokine IL-1cv15j862xf7at6/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">. We found that gilthead seabream head-kidney, peritoneal exudate and peripheral blood leukocytes accumulated proIL-1cv15j862xf7at6/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"> intracellularly when challenged in vitro with V. anguillarum, whereas only peritoneal exudate and blood leukocytes were able to accumulate proIL-1cv15j862xf7at6/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"> following infection. Importantly, the blood leukocytes from infected animals that accumulated proIL-1cv15j862xf7at6/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"> were shown to be the acidophilic granulocytes. A rapid mobilization of such cells from the head-kidney to the site of inflammation following infection with V. anguillarum was also observed. This work was supported by the Spanish Ministry of Science and Technology (grants BIO2001-2324-C02-02 and AGL2002-03529, and fellowship to J. García-Castillo), Spanish Ministry of Education, Culture and Sport (fellowship to E. Chaves-Pozo) and Fundación Séneca, Coordination Centre for Research (grant PI-51/00782/FS/01 and fellowship to P. Pelegrín).E. Chaves-Pozo and P. Pelegrín contributed equally to this work. 相似文献