全文获取类型
收费全文 | 3900篇 |
免费 | 324篇 |
国内免费 | 12篇 |
专业分类
林业 | 306篇 |
农学 | 203篇 |
基础科学 | 17篇 |
707篇 | |
综合类 | 275篇 |
农作物 | 247篇 |
水产渔业 | 460篇 |
畜牧兽医 | 1633篇 |
园艺 | 106篇 |
植物保护 | 282篇 |
出版年
2023年 | 52篇 |
2022年 | 82篇 |
2021年 | 193篇 |
2020年 | 211篇 |
2019年 | 236篇 |
2018年 | 193篇 |
2017年 | 213篇 |
2016年 | 199篇 |
2015年 | 144篇 |
2014年 | 197篇 |
2013年 | 242篇 |
2012年 | 269篇 |
2011年 | 304篇 |
2010年 | 162篇 |
2009年 | 151篇 |
2008年 | 157篇 |
2007年 | 176篇 |
2006年 | 119篇 |
2005年 | 112篇 |
2004年 | 95篇 |
2003年 | 111篇 |
2002年 | 106篇 |
2001年 | 62篇 |
2000年 | 62篇 |
1999年 | 41篇 |
1998年 | 22篇 |
1997年 | 16篇 |
1996年 | 8篇 |
1995年 | 13篇 |
1994年 | 12篇 |
1993年 | 12篇 |
1992年 | 17篇 |
1991年 | 11篇 |
1990年 | 13篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1983年 | 9篇 |
1981年 | 7篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1975年 | 7篇 |
1973年 | 7篇 |
1972年 | 9篇 |
1970年 | 6篇 |
1969年 | 9篇 |
1967年 | 5篇 |
排序方式: 共有4236条查询结果,搜索用时 15 毫秒
101.
J. Chatterjee A.K.A. Mandal S.A. Ranade Jaime A. Teixeira da Silva S.K. Datta 《Scientia Horticulturae》2006
An attempt was made to understand the molecular systematics and genetic differences between 10 original chrysanthemum cultivars and 11 mutants. The similarity among the cultivars and mutants varied from 0.17 to 0.90 using RAPD analyses, a simple but efficient method to distinguish cultivars and to assess parentage. Two distinct groups were found. Two cultivars were present as a separate group showing differences from all other cultivars. Mutants with different flower colour could be identified at the molecular level using RAPD technique holding promise to identify unique genes as SCAR markers. A high genetic distance among the different chrysanthemums showed that there exists a possibility of introgressing new and novel genes from the chrysanthemum gene pool. 相似文献
102.
Silvio Aparecido Lopes Guilherme Fernando Frare Pedro Takao Yamamoto Antonio Juliano Ayres José Carlos Barbosa 《European journal of plant pathology / European Foundation for Plant Pathology》2007,119(4):463-468
The huanglongbing (HLB) disease of citrus trees, caused by Candidatus Liberibacter asiaticus and Ca. Liberibacter americanus, was first reported in Brazil in March, 2004. The presence of the disease has caused serious concerns
among growers. Pruning experiments were conducted to determine if removal of symptomatic branches or the entire canopy (decapitation)
would eliminate infected tissues and save HLB-affected trees. Pruning was done in five blocks on a total of 592 3- to 16 year-old
‘Valência’, ‘Hamlin’ or ‘Pêra’ sweet orange trees showing no symptoms or with two levels of symptom severity. Ten decapitated
trees per block were caged and all trees were treated with insecticides to control the psyllid vector, Diaphorina citri. Mottled leaves reappeared on most symptomatic (69.2%) as well on some asymptomatic (7.6%) pruned trees, regardless of age,
variety, and pruning procedure. Presence of the pathogen (Ca. Liberibacter americanus) in all symptomatic trees was confirmed by PCR. In general, the greater the symptom severity before
pruning the lower the percentage of trees that remained asymptomatic after pruning. 相似文献
103.
Joseli da Silva Tatagiba Luiz Antonio Maffia Roberto W. Barreto Acelino C. Alfenas John C. Sutton 《Phytoparasitica》1998,26(1):8-19
Microbial isolates from living petals, petal residues and leaf residues of rose, and from laboratory collections, were evaluated
for control ofBotrytis cinerea in rose. In leaf residues artificially infested withB. cinerea, isolates of the filamentous fungiGliocladium roseum, FR136 (unidentified) andTrichoderma inhamatum reduced sporulation of the pathogen by >90%, other filamentous fungi were 25–90% effective, and those of yeasts and bacteria
were <50% effective. In artificially inoculated petal residues, no microbe reduced sporulation ofB. cinerea by >75%, but isolates ofCladosporium oxysporum and four yeasts were 51–75% effective, and three filamentous fungi, eight yeasts andBacillus subtilis isolates were 26–50% effective. Isolates ofT. inhamatum, C. oxysporum andG. roseum performed best againstB. cinerea among isolates evaluated in leaf residues naturally infested with the pathogen and indigenous microorganisms. Totals of ten
isolates of filamentous fungi (includingC. oxysporum andC. cladosporioides), two of yeasts and five ofBacillus subtilis completely prevented lesion production byB. cinerea in detached petals, and a further six isolates of filamentous fungi (includingG. roseum) and six yeasts were 90–99% effective. Isolates ofC. oxysporum, C. cladosporioides andB. subtilis, the most effective microorganisms againstB. cinerea in flower buds, reduced number of lesions in the range of 42–65% compared with 59–89% for à standard fungicide (vinclozolin).
It is suggested that application of leading antagonists Jo living rose leaves and flowers should optimize control of inoculum
production byB. cinerea when the tissues die. Optimal biocontrol of lesion production in flower buds requires a better understanding of the microenvironment
of petals. 相似文献
104.
Fernando G. Barroso Ana Rodiles Antonio J. Vizcaino Tomás F. Martínez Francisco J. Alarcón 《Journal of the World Aquaculture Society》2013,44(5):682-693
The Senegalese sole, Solea senegalensis, is a flatfish with increasing interest in the European aquaculture. However, one of the main limitations found in this species is related to the scarce attraction to commercial aquafeeds, thus determining low feed intake in fish farms. The aim of this study was to evaluate four ingredients of marine origin (fish meal hydrolysate [FMH], polychaete meal [POM], mussel meal [MUM], and squid meal [SQM]) as potential attractants for juvenile Senegalese sole. Four experimental feeds containing 10% of the potential attractants, plus a control diet without these ingredients, were evaluated. A total of 150 fish were distributed into ten 40‐L tanks (duplicate tanks per feed). A Latin square design was carried out, and hence all the experimental diets were offered to each tank in successive periods of 7 d. Fish were fed twice a day (morning and afternoon), and the feeding behavior of the animals was assessed by direct observations. Behavioral pattern assessed was classified as distant orientation, near orientation, or continuation of intake. The acceptability index for each behavioral phase and experimental feeds used was established for each observation. No behavioral differences could be noticed between the morning and the afternoon feedings. FMH showed the greatest attractant potential than among the ingredients assessed, and consequently this ingredient yielded the higher feed intake rates. On the other hand, POM was not the best attractant for juvenile Senegalese sole. 相似文献
105.
106.
Nancy P. Chaves Luis E. Pocasangre Fritz Elango Franklin E. Rosales Richard Sikora 《Scientia Horticulturae》2009,122(3):472-478
Eight endophytic fungal and bacterial isolates with antagonistic activity against Radopholus similis were evaluated in vivo for their individual and combined effects on biocontrol of R. similis and on the growth of “Grand Naine” cultivar banana plantlets in the greenhouse. Penetration efficiency (PE) of R. similis was between 3 and 21% in 29 biological agents (BAs) treatments, less than the 29% of the nematode-alone control (p ≤ 0.0001); 24 of the BAs treatments did not differ from the PE of 5% for a nematicide control. Twenty nine BAs treatments exhibited antagonistic activity against nematodes which reduced final population levels between 18 and 93%, relative to those on nematode-alone control plants (p ≤ 0.0001), and 14 BAs treatments were statistically similar to the nematicide treatment (88% reduction). Twenty four BAs treatments had increments of plant root biomass ranging from 20 to 58%, greater than the control plants; 37% of the treatments with single and combined BAs inoculations had root length increments ranging from 29 to 54% compared with control and chemical treatment. The nematicide, Terbufos 10GR, did not affect plant growth. 相似文献
107.
Fabrício Alves Oliveira Derly José Henriques da Silva Germano Leão Demolin Leite Gulab Newandram Jham Marcelo Picanço 《Scientia Horticulturae》2009
The aim of this study was to evaluate resistance to Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) by antixenosis on 57 Lycopersicon esculentum Mill. accessions from the Horticultural Germplasm Bank (HGB) of Universidade Federal de Viçosa and by the three commercial cultivars (Santa Clara, Moneymaker and TOM-601) under greenhouse conditions. A randomized complete block design was used with three replications. Infestations with T. absoluta adults were performed weekly and the following characteristics were evaluated: number of small, large and total mines/leaf and % of leaves mined at days 60, 75 and 90 after planting. Low infestation occurred at days 60 and 75 but at day 90, infestation was sufficient to evaluate insect damage. Based on these data it was concluded that only accessions HGB-674 and HGB-1497 appeared to be the most promising. In addition, to determine possible chemical causes of resistance, hexane extracts were analyzed at day 90 by gas chromatography/mass spectrometry and the major peaks identified by a mass spectral database using similarity index. Nine hydrocarbons, viz., hexadecane, heptadecane, eicosane, tricosane, 2-methyltricosane, tetracosane, hexacosane, octacosane and triacontane were identified in the hexane extracts in many samples. Tricosane, tetracosane and hexacosane presented significant correlations with the leaves mined. Only tricosane presented a negative correlation with the number of small mines (r = −0.28), total number of mines (r = −0.27) and % of leaves mined (r = −0.22). However, tetracosane and hexacosane presented significant positive correlations (r = 0.25 and 0.24, respectively) with the % of leaves mined. 相似文献
108.
Costa JZ Adams A Bron JE Thompson KD Starkey WG Richards RH 《Journal of fish diseases》2007,30(7):419-426
The pepscan procedure was used to identify betanodavirus B-cell epitopes recognized by neutralizing mouse monoclonal antibodies (MAbs) and serum samples obtained from sea bass, Dicentrarchus labrax, naturally infected with betanodavirus. Pepscan was performed with a panel of thirty-four 12-mer synthetic peptides that mimicked the entire betanodavirus capsid protein. Sea bass serum samples reacted strongly with three regions of the capsid protein comprising amino acid residues 1-32, 91-162 and 181-212. The latter region was also recognized by neutralizing MAbs and coincided with a region of high antigenic propensity identified by an antigen prediction algorithm. These data suggest that a region of the betanodavirus capsid protein spanning amino acid residues 181-212 may represent a neutralization domain that could potentially be used to inform the development of nodavirus vaccines and immunodiagnostic reagents. 相似文献
109.
C. FERNANDES da SILVA E. BALLESTER J. MONSERRAT L. GERACITANO W. WASIELESKY JR P.C. ABREU 《Aquaculture Nutrition》2008,14(6):507-514
The nutritional quality of biofilm, a microbial community associated to an organic matrix, was evaluated in artificial substrate (polyethylene screen) in net cages during 30 days in the Patos Lagoon estuary, Southern Brazil. During this period, samples of biofilm were collected each 5 days for analysis of chlorophyll a, microorganisms abundance, dry weight, protein and lipid contents. During the study, chlorophyll a varied from 0.38 to 2.75 μg cm?2; dry weight between 7.16 and 17.63 mg cm?2; protein content from 0.43 to 1.76 mg cm?2 and lipid concentration between 1.21 and 4.23 mg cm?2. The variation of lipid in the biofilm was closely related to the abundance of free heterotrophic bacteria (34.25–56.54 × 106 cells cm?2), filamentous cyanobacteria (7.5–15.9 × 106 filaments cm?2), flagellates (6.92–12.89 × 106 cells cm?2) and mainly nematodes (29–1,414 organisms cm?2), while protein content varied similarly to the abundance of unicellular centric diatoms (52.10–179.81 × 103 cells cm?2), and nematodes. This information will allow a better management of food supply to raised aquatic organism with the utilization of natural productivity in the culture systems, with considerable decrease in production costs. 相似文献
110.
Franklin WS 《Science (New York, N.Y.)》1900,12(310):887-890