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111.
Fecteau G Fairbrother JM Higgins R Van Metre DC Paré J Smith BP Holmberg CA Jang S 《Veterinary microbiology》2001,78(3):241-249
Twenty-five Escherichia coli isolates from the blood of critically ill bacteremic calves sampled in two separate studies on a calf-rearing farm housing over 15,000 calves, in the San Joaquin Valley, California were studied.Isolates were characterized for O serogroups and for pathotypes as determined by the presence of specific virulence factors including heat-labile enterotoxin (LT), heat-stable enterotoxins a and b (STa, STb), verotoxins 1 and 2 (VT1, VT2), cytotoxic necrotizing factor (CNF), aerobactin, intimin Eae and P, F17 and CS31A fimbrial adhesins, and resistance to bactericidal effects of serum.These isolates constituted a heterogeneous group. However, isolates were mostly aerobactin positive and often resistant to the bactericidal effects of serum. Isolates of pathotypes O78 (n=6), O119:CS31a (n=3), and P positive but O non-typeable (n=3) were associated with a high mortality rate. The remaining isolates belonged to diverse pathotypes, often possessing the adhesins P, F17, CS31A and Eae but belonging to O serogroups other than O78 and O119, and were less frequently associated with mortality.Although no virulence factor common to all isolates was identified, the capacity to use iron by the presence of aerobactin which is important to the capture of iron was a predominant factor. Moreover, certain pathotypes appear to be associated with primary colisepticemia whereas other pathotypes may cause a bacteremia without necessarily leading to septicemia. 相似文献
112.
Van Overbeke I Chiers K Ducatelle R Haesebrouck F 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2001,48(1):15-20
The efficacy of a subunit vaccine containing the Apx toxins of Actinobacillus pleuropneumoniae and transferrin-binding proteins was determined. Ten pigs were vaccinated twice with the vaccine. Eight control animals were injected twice with a saline solution. Three weeks after the second vaccination, all pigs were endobronchially inoculated with 10(6.5) colony-forming units (CFU) of an A. pleuropneumoniae serotype 9 strain. In the vaccine group, none of the pigs died after inoculation. Only one pig of the control group survived challenge. Surviving pigs were killed at 7 days after challenge. The mean percentage of affected lung tissue was 64% in the control group and 17% in the vaccine group. Actinobacillus pleuropneumoniae was isolated from the lungs of all animals. The mean bacterial titres of the caudal lung lobes were 5.0 x 10(8) CFU/g in the control group and 3.0 x 10(6) CFU/g in the vaccine group. It was concluded that the vaccine induced partial protection against severe challenge. 相似文献
113.
Cet article présente les premières listes de nématodes parasites des plantes (Tylenchida et Dorylaimida) des départements français d'Amérique: Guadeloupe, Martinique et Guyane. Ces listes ont étéétablies suite aux nombreuses enquêtes faunistiques en nématologie conduites dans ces départements depuis les premiers résultats d'analyses nématologiques de Scotto La Massèse en 1968. L'inventaire général comporte 171 entrées taxinomiques, réparties en 42 genres et 18 nouvelles espèces. Ainsi, à la Guadeloupe, 82 espèces ont été inventoriées dont 3 espèces nouvelles; à la Martinique, 87 espèces ont été inventoriées dont 7 espèces nouvelles; et en Guyane, 97 espèces ont été inventoriées dont 8 espèces nouvelles. Quelques-unes de ces espèces sont sur les listes A1 et A2 de l'OEPP ( Aphelenchoides besseyi A2/122, Radopholus similis A2/126, Xiphinema americanum sensu lato A1/150 et Xiphinema rivesi A2/262). L'intérêt de telles études en nématologie est discuté ainsi que les dispositions réglementaires quant à la présence d'espèces économiquement importantes ou réglementées, au regard de l'accroissement des échanges inter-îles ou intercontinentaux et des risques phytosanitaires encourus, que ce soit dans les départements français d'outre-mer (DOM) ou les pays et territoires d'outre-mer (PTOM). 相似文献
114.
115.
M. Van Oijen 《European journal of plant pathology / European Foundation for Plant Pathology》1992,98(1):3-11
A field experiment with three potato cultivars, where plants were inoculated withPhytophthora infestans, was used to parameterize a model of potato growth and blight population dynamics. The model was validated by accurately simulating a field experiment conducted in another year. Sensitivity analysis with the model showed that late cultivars are longer able to maintain a green canopy in the presence of disease, but still suffer more yield loss than early cultivars. The level of partial resistance of a cultivar was more important than its level of tolerance, and other plant characteristics. The model calculations showed that only between 4 and 15% of the yield loss in the experiments was due to accelerated leaf senescence caused by the disease; the major part of the loss was caused by lesion coverage of leaves. 相似文献
116.
J. E. Van Den Ende 《European journal of plant pathology / European Foundation for Plant Pathology》1992,98(4):227-236
A greenhouse screening method for resistance to ringspot (Mycosphaerella brassicicola) inBrassica oleracea is described. High infection levels were achieved by spraying young plants by mycelial inoculum enriched with 3% sucrose. The screening method was tested on three Brussels sprouts, three cabbage and three cauliflower cultivars, with known reactions to ringspot in the field. Resistance was expressed both in cotyledons and true leaves by a lower number of lesions than the susceptible control and/or by hypersensitive reactions. Results of the seedling tests reflected differences in resistance in the field. Under controlled conditions the new test can be applied year-round to young plants, thus accelerating selection procedures. 相似文献
117.
Marianne J. Huisman Erik Jongedijk Dinie Posthumus-Lutke Willink Frank Van Der Wilk Ben J. C. Cornelissen 《European journal of plant pathology / European Foundation for Plant Pathology》1992,98(2):29-36
To engineer resistance against potato virus X (PVX), the viral coat protein (CP) gene has been introduced into two potato cultivars. Stable expression of the gene in transgenic clones throughout the growing season has been obtained and resulted in considerably increased virus resistance. With varying frequencies depending on the original cultivar used, true-to-type PVX resistant transgenic clones have been obtained. Since deviant light sprout characteristics were invariably associated with aberrations in plant phenotype, they can be used in procedures to early screen for deviations. Furthermore, it has been possible to unequivocally discriminate between the original untransformed and independent transgenic cultivars. Although no relation has been found between the presence, if any, of the CP of potato virus Y (PVY) or potato leafroll virus (PLRV) in CP gene transgenic potato, appreciable levels of resistance to these viruses has been obtained. This suggests that the mechanism by which a viral CP gene in the potato genome evokes resistance, differs amongst various viruses. 相似文献
118.
D. Craig Heim George G. Kennedy Fred L. Gould John W. Van Duyn 《Pest management science》1992,34(4):303-311
Progeny from reciprocal F1 crosses and F1 backcrosses between fenvalerate-resistant and fenvalerate-susceptible Colorado beetles, Leptinotarsa decemlineata (Say), and between carbofuran-resistant and carbofuran-susceptible Colorado beetles were bioassayed to investigate the mode of inheritance of resistance to these chemicals. Bioassays of progeny from these crosses indicate that resistance to fenvalerate is inherited in a semi-recessive, sex-linked manner and carbofuran resistance is inherited in a partially dominant autosomal fashion. Log concentration/probit mortality lines and chi-square tests, however, indicate that multiple genes may be involved in resistance to both insecticides. 相似文献
119.
Henk J. Van Oosten 《Pest management science》1992,34(4):365-381
The Dutch government has a coherent, long-term policy regarding attainment of a sustainable development affecting agriculture and horticulture, the requirements of which are very strict and will be difficult to satisfy. The growers of protected crops try to meet these requirements by developing so-called closed growing systems. Two other approaches in the policy are a substantial reduction of the volume of pesticides used and a very critical evaluation of the pesticides permitted. In this governmental policy, Integrated Pest Management has shown prospects in horticulture; it will play a very important role in the near future but is now considered as part of the broader concept of Integrated Production Systems. The glasshouse industry is very actively developing its own strategy to satisfy government targets and market demands for high-quality products produced by environmentally safe methods. The vegetable auctions have developed a policy of environmentally conscious production which should put the vegetable industry into a strong marketing position for its produce. 相似文献
120.
Doris Van Der Krol Ingolf Schuphan Brigitte Thiede Burkhard Schmidt 《Pest management science》1995,45(2):143-152
By means of standardized procedures, the metabolism of [ring-2,6-14C]-parathion was investigated in carrot (Daucus carota L.), purple foxglove (Digitalis purpurea L.), soybean (Glycine max Merrill cv. ?Mandarin’?, and Glycine max Merrill cv. ?Harosoy 63’? cultivated on B5 and Miller media, respectively), thorn apple (Datura stramonium L.), and wheat (Triticum aestivum L.) cell suspension cultures. In the wheat and soybean (Mandarin) cells only 2.9 and 8.9%, respectively, of the applied parthion remained unmetabolized after 48 h of incubation, while 51.2, 57.9, 60.3, and 62.4% of the unchanged parent were detected in the D. purpurea, D. Stramonium, carrot and soybean (Harosoy) cultures, respectively. In all suspensions, paraoxon and 4-nitrophenol were found as phase I metabolites, thus demonstrating that plant tissues can catalyse oxidative desulfuration and dearylation of parathion. 4-Nitrophenol was also glycosylated with glucose and possibly galactose. Further, as yet unidentified, metabolites indicated that bio-transformations had also occurred at the aromatic moiety. Large amounts of non-extractable residues were detected in the wheat suspension (38.3%), while the other cultures showed a lower incorporation of 14C into insoluble cell material (0.9-9.4%). For a prospective ecotoxicological evaluation of the metabolic fate of pesticides and xenobiotics in plants in general, the differential metabolic capacity of plant cell cultures and plants should be taken into account. 相似文献