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551.
552.
Philip J. Newton 《Entomologia Experimentalis et Applicata》1989,52(2):113-117
The oviposition response of Cryptophlebia leucotreta (Meyrick) (Lepidoptera: Tortricidae) to healthy navel and Valencia orange, Citrus sinensis (L.), fruit was measured in experimental orchards at Nelspruit, eastern Transvaal, South Africa, and was compared with the response to prematurely ripened fruit and injured fruit. Both premature ripening and injury increased the number of eggs laid on these fruit. Damaged fruit was almost twice as attractive as ripe fruit if the number of eggs laid can be used as a measure of attraction. Large wounds were no more stimulating than small lesions. The quantity of stimulus was not statistically significant, yet five or ten treated fruit in a cluster led to more egg-laying per fruit than a single treated fruit. More eggs were observed on healthy fruit within 50 cm of clusters of treated fruit than on healthy fruit on different trees, but this effect was not statistically significant.
Résumé La ponte de c. leucotreta Meyrick (Lep.; Tortricidae) sur oranges (Navel et Valencia) saines a été évaluée dans des vergers expérimentaux de Nelspruit à l'est du Transvaal, en Afrique du Sud. Elle a été comparée à la ponte observée sur des fruits prématurés ou endommagés. Ces deux dernières situations ont augmenté l'effectif d'ufs pondus sur les fruits; si le nombre d'ufs pondus est utilisé comme critère d'attraction, les fruits endommagés étaient presque deux fois plus attractifs que les autres. La taille des blessures est sans effet. Des fruits ont été artificiellement endommagés ou conduits prématurément à maturité avec un badigeon d'acide 2-chloréthylphos-phorique. Ces stimului n'ont pas eu d'effet cumulatif significatif; pourtant la ponte était plus importante sur des paquets de 5 ou 10 fruits artificiellement modifiés, que sur des fruits modifiés isolés. Une ponte plus importante a été observée sur des fruits sains à moins de 50 cm d'un groupe de fruits modifiés. Il est probable que des signaux visuels et olfactifs orientent la découverte du fruit par la tordeuse. Ces résultats suggèrent que les substances volatiles ont plus d'influence que la couleur ou la taille du fruit.La protection contre cet insecte devrait comprendre l'élimination des fruits mûris prématurément ou abîmés, mais il faudrait préciser si les fruits endommagés sont ou non découverts par hasard. La concentration des pontes sur et autour de ces fruits peut aussi réduire les pontes dans le reste du verger.相似文献
553.
M. P. E. van Gent -Pelzer I. R. van Brouwershaven L. F. F. Kox P. J. M. Bonants 《Journal of Phytopathology》2007,155(6):357-363
With respect to disease risk for the quarantine fungus Guignardia citricarpa on citrus fruit an accurate diagnosis for routine analysis is required. Also, when inspections have to be performed on imported citrus fruits, a fast detection method is urgently needed. A fast automated DNA extraction method based on magnetic beads combined with a real‐time PCR assay was optimized to improve and advance the routine diagnosis of citrus black spot disease. Real‐time PCR was used for detection of the pathogen G. citricarpa in planta. A specific primer/TaqMan probe combination that discriminates between G. citricarpa and the harmless citrus endophyte Guignardia mangiferae, was designed based on the internal transcribed spacer region of the multi‐copy rDNA gene. Co‐amplification of target DNA along with an internal competitor DNA fragment made the diagnostic assay more reliable to check for false negatives. The real‐time PCR was specific, since no cross reaction was observed with a series of citrus pathogens and related species. The diagnostic assay was performed on lesions dissected from imported diseased oranges. Comparison between the conventional PCR and the real‐time PCR methods showed that the TaqMan method was more sensitive. 相似文献
554.
柑橘大实蝇对不同柑橘品种的产卵偏好和幼虫取食选择 总被引:4,自引:0,他引:4
【目的】掌握柑橘大实蝇Bactrocera minax对不同品种柑橘的产卵偏好,以及与幼虫取食喜嗜性的关系。【方法】我们用五点取样法分别调查了自然条件下不同品种柑橘果园的虫果率,统计了各品种柑橘虫果基半部和端半部产卵痕量和卵量,并在实验室内采用培养皿桔瓣选择法研究了其幼虫对不同柑橘品种果实的取食选择。【结果】在未采取防控措施的情况下,果树面朝杂树林的方位虫果率显著高于其他方位;同一片受害柑橘园内,不同柑橘品种的虫果率为脐橙Citrus sinensis cv. Navel、酸橙C. aurantium>冰糖橙C. sinensis cv. Bingtang、天草(Amakusa)、蜜橘C. reticulata cv. Satsuma>沙田柚C. maxima cv. Shatian>椪柑C. reticulata cv. Ponkan;柑橘大实蝇产卵痕数和卵量均为橙类(脐橙、酸橙和冰糖橙)大于橘类(天草、蜜橘和椪柑)和沙田柚(P<0.05);除蜜橘外,所调查的其他柑橘品种端半部的产卵痕数显著多于基半部(P<0.05);幼虫对不同品种柑橘橘瓣肉的取食选择顺序依次为:脐橙、酸橙>冰糖橙>天草、南橘C. reticulata cv. Nanju>蜜橘>椪柑>沙田柚。【结论】结果提示,柑橘大实蝇成虫偏向于选择幼虫所喜嗜的橙类品种产卵,且产卵量更多。 相似文献
555.
Erik J. Wenninger Lukasz L. Stelinski & David G. Hall 《Entomologia Experimentalis et Applicata》2008,128(3):450-459
Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is an important worldwide pest of citrus. It vectors three phloem-restricted bacteria in the genus Candidatus Liberibacter that cause huanglongbing (citrus greening disease). Studies were conducted to examine the behavioral responses of male and female D. citri to conspecifics of the same and opposite sex, with and without associated citrus host plants, in both open-air arena choice assays and Y-tube olfactometer assays. Virgin and mated male D. citri colonized citrus plants that were currently or had been previously colonized by virgin or mated female D. citri in greater numbers than control plants without females. However, males or females did not accumulate more on plants colonized by conspecifics of the same sex compared to uninfested plants, and females showed no preference for plants pre-infested with males compared with uninfested controls. In complementary Y-tube olfactometer assays, virgin and mated males chose arms with odor sources from mated females compared with blank controls in the absence of associated citrus host plant volatiles. In both behavioral assays, mated female D. citri appeared more attractive than virgin females. The vibrational calling behavior of male D. citri was reduced when males were challenged by the odors of conspecific mated females relative to when males were challenged by the odor of other males. Collectively, our results provide behavioral evidence for a female-produced volatile sex attractant pheromone in D. citri . Future identification and synthesis of a sex attractant pheromone will be an important contribution to current monitoring and management practices for D. citri . 相似文献
556.
J.C. Franco E.B. Silva E. Cortegano L. Campos M. Branco A. Zada & Z. Mendel 《Entomologia Experimentalis et Applicata》2008,126(2):122-130
The occurrence of a kairomonal response of the parasitoid Anagyrus spec. nov. near pseudococci (Hymenoptera: Encyrtidae) to (+)‐(1R,3R)‐cis‐2,2‐dimethyl‐3‐isopropenyl‐cyclobutanemethanol acetate (PcA, namely, planococcyl acetate) and (S)‐(+)‐lavandulyl senecioate (LS), the respective female sex pheromones of its hosts, the citrus mealybug, Planococcus citri (Risso) and the vine mealybug, Planococcus ficus (Signoret) (Homoptera: Pseudococcidae) was investigated. Attraction to the pheromones was tested by employing pheromone traps in field trials and by static air olfactometer bioassays in the laboratory. Female wasps showed a significant response to LS, in both field and olfactometer experiments. No significant response was registered to the sex pheromone of P. citri. Despite the similarity between the structures of LS and its analogue (S)‐(+)‐lavandulyl isovalerate (LI), no significant response to the latter compound was observed. It seems that differences between the structures of the carboxylate moiety of the respective molecules (LS and LI) markedly affect the kairomonal attractiveness to the parasitoid. The kairomonal response of Anagyrus spec. nov. near pseudococci was neither influenced by the host habitat nor by the host species on which it developed. This suggested innate behaviour of Anagyrus spec. nov. near pseudococci, possibly derived from evolutionary relationships between the parasitoid and P. ficus. The practical implications of the results are discussed. 相似文献
557.
Sean D. Moore Timothy Pittaway Gustav Bouwer Jeremy G. Fourie 《Biocontrol Science and Technology》2004,14(3):239-250
A concentration of 1.15×107 OBs/mL of HearNPV, sprayed using a knapsack, resulted in a 100% reduction in Helicoverpa armigera larval infestation within 7 days on tomato plants in a hot house environment. A 10-fold lower concentration, 1.15×106 OBs/mL, resulted in a 100% reduction within 16 days. These two concentrations reduced damage to tomatoes by 81 and 69%, respectively. In two field trials on navel oranges, the lower concentration and an additional even lower concentration of 7.26×105 OBs/mL, both resulted in a 100% reduction in H. armigera infestation within 14 days or longer. H. armigera damage to fruit was reduced by up to 84 and 75%, respectively, in the two trials. Rejection for export was reduced by 96 and 62%. This could imply a saving of US$339 per hectare compared to the untreated control. These results were better than those achieved with Bacillus thuringiensis and various standard chemical insecticides used in the same trials. Reasons for these results are discussed. 相似文献
558.
Montero-Astúa M Chacón-Díaz C Aguilar E Rodríguez CM Garita L Villalobos W Moreira L Hartung JS Rivera C 《Journal of microbiology (Seoul, Korea)》2008,46(5):482-490
Coffee plants exhibiting a range of symptoms including mild to severe curling of leaf margins, chlorosis and deformation of
leaves, stunting of plants, shortening of internodes, and dieback of branches have been reported since 1995 in several regions
of Costa Rica’s Central Valley. The symptoms are referred to by coffee producers in Costa Rica as “crespera” disease and have
been associated with the presence of the bacterium Xylella fastidiosa. Coffee plants determined to be infected by the bacterium by enzyme linked immunosorbent assay (ELISA), were used for both
transmission electron microscopy (TEM) and for isolation of the bacterium in PW broth or agar. Petioles examined by TEM contained
rod-shaped bacteria inside the xylem vessels. The bacteria measured 0.3 to 0.5 μm in width and 1.5 to 3.0 μm in length, and
had rippled cell walls 10 to 40 nm in thickness, typical of X. fastidiosa. Small, circular, dome-shaped colonies were observed 7 to 26 days after plating of plant extracts on PW agar. The colonies
were comprised of Gram-negative rods of variable length and a characteristic slight longitudinal bending. TEM of the isolated
bacteria showed characteristic rippled cell walls, similar to those observed in plant tissue. ELISA and PCR with specific
primer pairs 272-l-int/272-2-int and RST31/RST33 confirmed the identity of the isolated bacteria as X. fastidiosa. RFLP analysis of the amplification products revealed diversity within X. fastidiosa strains from Costa Rica and suggest closer genetic proximity to strains from the United States of America than to other coffee
or citrus strains from Brazil. 相似文献
559.
560.