全文获取类型
收费全文 | 316篇 |
免费 | 13篇 |
国内免费 | 14篇 |
专业分类
林业 | 27篇 |
农学 | 21篇 |
基础科学 | 11篇 |
56篇 | |
综合类 | 75篇 |
农作物 | 11篇 |
水产渔业 | 17篇 |
畜牧兽医 | 83篇 |
园艺 | 19篇 |
植物保护 | 23篇 |
出版年
2023年 | 4篇 |
2022年 | 12篇 |
2021年 | 10篇 |
2020年 | 15篇 |
2019年 | 8篇 |
2018年 | 12篇 |
2017年 | 19篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 15篇 |
2013年 | 12篇 |
2012年 | 23篇 |
2011年 | 19篇 |
2010年 | 20篇 |
2009年 | 19篇 |
2008年 | 13篇 |
2007年 | 12篇 |
2006年 | 22篇 |
2005年 | 18篇 |
2004年 | 6篇 |
2003年 | 12篇 |
2002年 | 6篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 9篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1970年 | 3篇 |
1969年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有343条查询结果,搜索用时 15 毫秒
101.
Feza Can Nihat Demirel Erkan Isa Sağıroğlu Teodora Toshova Mitko Subchev 《Phytoparasitica》2010,38(3):217-222
The vine bud moth, Theresimima ampellophaga (Bayle-Barelle 1808) (Lepidoptera: Zygaenidae; Procridinae), is a pest on grape vine, Vitis vinifera (L.), and on the ornamental vine Parthenocissus quinquefolia (L.) and other Parthenocissus species. Its recent distribution in Europe is relatively well known, but there is a paucity of locality data for Turkey. As a consequence, we began a large-scale investigation into its distribution and seasonal activity in this country in 2008. The main tools for these investigations were pheromone traps that were baited with the synthetic pheromone of the species, viz. (2R)-butyl (Z7)-tetradecenoate. As a result of field work carried out in the eastern Mediterranean region of Turkey in 2008 and 2009, Th. ampellophaga was recorded in five provinces, viz. Adana, Mersin, Hatay, Kahramanmara? and Kilis. The only province where the pest was not found was Gaziantep. Theresimima ampellophaga produces one or two generations per year, depending on the local conditions and other unknown factors. The moths of the first generation fly in June, while those of the second generation occur in August. To the best of our knowledge the present paper provides the first well-documented evidence of the occurrence of a second generation of the vine bud moth in Turkey. 相似文献
102.
SUN Yi-hua ZHANG Li XU Chang-qing LI Hong SHI Sa ZHAO Ya-jun HAN Li-ping ZHANG Hong-yu 《园艺学报》2006,22(8):1506-1509
AIM:To investigate the changes of expression of calcium-sensing receptor (CaSR) in the rat cardiac tissue at different age and its relation with anoxia -reperfusion (A/R) injury.METHODS:RT-PCR was used to detect the mRNA expression of CaSR.The A/R injury was remodeled in vitro,and the ultrastructure of cardiac tissue was observed under transmission electron microscope.RESULTS:The expression of CaSR mRNA in the rat cardiac tissue increased gradually after birth,and reached to its maximum in the 1st month.In the 2nd to 3rd month,the expression were almost equal to that at birth and then increased again to a higher level.The expression level of CaSR mRNA increased more significantly than those in control groups after 40 min of anoxia and reperfusion of 1 h and 2 h,and decreased after 3 h and 4 h.Moreover,the longer the reperfusion time lasted,the more serious the changes of ultrastructure were observed.CONCLUSION:Our results demonstrate that the CaSR is expressed in the rat cardiac tissue.The mRNA expression of CaSR changes with age and is involved in the anoxia -reperfusion injury. 相似文献
103.
104.
In the search for new sources of sesquiterpene lactones, six Centaurea species have been analyzed. The activity against the fungus Cunninghamella echinulata of (+)-cnicin (1) and (+)-salonitenolide (2), isolated from the Centaurea plants, as well as that of (+)-costunolide (3), (-)-dehydrocostuslactone (4), (-)-lychnopholide (5) and (-)-eremantholide C (6), has been evaluated. Compounds 3 and 4 showed noticeable EC50 values, whilst more polar lactones were inactive. These results suggest that a relatively low polarity is one of the molecular requirements for the antifungal activity of sesquiterpene lactones. 相似文献
105.
中国梨黑星菌(Venturia nashicola)致病性分化的研究 总被引:4,自引:0,他引:4
从我国梨产区河北、江苏、浙江、台湾和四川等地不同梨品种上分离到的12个梨黑星菌(Venturia nashicola)的单孢菌株,采用田间抗病性不同的品种接种、进行致病力测定,结果表明:寄生在我国栽培梨上的黑星菌存在生理分化,供试的12个单孢菌株,初步划分为5个不同的致病类型。 相似文献
106.
107.
Ravi S. Gadagi P. U. Krishnaraj J. H. Kulkarni Tongmin Sa 《Scientia Horticulturae》2004,100(1-4):323-332
The investigation was carried out to examine the performance of Azospirillum isolates on growth and N uptake of Gaillardia pulchella with two nitrogen levels. Azospirillum strain OAD-2 inoculation significantly increased plant height, number of leaves per plant, branches per plant and total dry mass accumulation in G. pulchella than other inoculations and/or uninoculated control. The application of 150 kg N ha−1 further enhanced the above plant growth parameters significantly over application of 112 kg N ha−1. The N uptake of G. pulchella was enhanced due to Azospirillum strain OAD-2 inoculation, which was further augmented in the presence of nitrogen. The combination of Azospirillum strain OAD-2 and 150 kg N ha−1 showed the highest N uptake at 120 DAT. Plant growth and yield parameters also increased when inoculated with the non-diazotrophic, but efficient IAA producing, Azospirillum strain OAD-57. From this investigation, it can be concluded that Azospirillum strains OAD-2 and OAD-11 can play an important role in the N nutrition of G. pulchella. 相似文献
108.
Mhemmed Gandour Mohamed Larbi Khouja Lamjed Toumi Saîda Triki 《Annals of Forest Science》2007,64(5):549-555
Twenty-six provenances (2 340 plants) of cork oak (Quercus suber spp.) originating from Portugal, Spain, Italy, Morocco, Algeria, and Tunisia were tested for genetic variation among and within provenances by growth traits. Seven morphometrical characters were measured in 90 plants from each provenance. Analysis of variance showed highly significant differences for all characters. The phenotypic coefficient of differentiation reached 0.24 for the form and 0.22 for height, thus revealing a strong structuring between the provenances. Comparative study of growth among the provenances revealed more vigorous growth and better survival rate for those from Morocco, Spain, and Portugal, which may constitute better materials for afforestation. Furthermore, this variability appeared to be geographically structured and would be mainly genetically controlled, as cork oak provenances were cultivated under the same environmental conditions. Our results should be helpful for guide forest managers in afforestation. 相似文献
109.
Drought is one of the crucial factors limiting plant growth and is expected to become even more limiting in many regions as the effects of climate change increase. Knowledge of genetic adaptation to environmental factors can help develop strategies for successful reforestation in arid terrain. In this study, Austrian pine (Pinus nigra Arnold) seedlings grown from seed collected from 40 open-pollinated families from five Balkan Peninsula provenances were evaluated for survival and growth under imposed drought. Within each provenance, seed was collected from an extremely harsh habitat and from a favorable habitat. One-year-old seedlings, from each provenance, habitat type and open pollinated family were transplanted into three “stressbeds”, each designed to simulate different levels of water availability by filling with varying ratios of crushed stone and soil. Seedling height growth and survival were recorded every 20–30?days from April–September. In all provenances, seedlings grown from seed originating from the harsh habitats had lower survival regardless of stressbed treatment compared to those grown from seed collected from favorable habitats, with the exception of one population from the Vi?egrad provenance which had high survival rates throughout. Overall height growth was very low and did not follow consistent patterns among treatment groups. Cluster analyses of survival data showed that populations from a similar habitat generally grouped together, regardless of provenance. The lowest and highest survival values were found in seedlings from harsh habitats, while those from the favorable habitats clustered in the mid-range. These results suggest that higher seed quality from productive stands may be the most influential factor determining seedling vigor under drought stress and that genetic adaptation to drought was not detected in adjacent populations having different habitat conditions. 相似文献
110.
Sa Chao* Du Hongbo Zhang Biguang Wang Guozhu School of Technology Beijing Forestry University Beijing P. R. China 《中国林学(英文版)》2003,5(4)
1IntroductionVeneermoisturecontent(MC)anditsdistributionserveasanimportanttechnologicalparameterindicatingdryingqualities.Accordingtomanufacturingplywoodtheory(Lu1993),toohighortoolowaMCdirectlyaffectsproductqualities.Theformerwillcausesomedefectssuchasungluing,split,distortion,etc.Andthelatterwillresultnotonlyinanincreaseinproductioncost,butalsoinadeclineinproductqualitiesduetothepartialcarbonizationontheveneersurfaceanddamagingtothefiber抯physicalproperties.Atpresent,mostoftheplywoodmanuf… 相似文献