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51.
Parasitic bronchitis caused by the bovine lungworm, Dictyocaulus viviparus, occurs worldwide in temperate areas. The parasite is found predominantly in calves and heifers, but dairy cattle can suffer from lungworms when they become infected for the first time or if they have lost immunity due to lack of exposure to lungworm larvae during the grazing season. The present study was performed to determine the D. viviparus bulk milk antibody prevalence in dairy herds in the East Frisian region of northwestern Germany, Lower Saxony, by analysing bulk milk samples collected in January (860 samples), September (866 samples) and November (860 samples) 2008, thereby representing 906 dairy farms. These samples were tested for antibodies against D. viviparus by a milk ELISA. This test detects patent infections only since it is based on recombinant major sperm protein as antigen. While in January 12.8% of dairy farms were positive for D. viviparus antibodies, the bulk milk samples collected in September and November revealed 6.9% and 6.6% positive dairy herds. From the 906 dairy farms included in the study, 191 (21.1%) tested positive at least once for antibodies against lungworm. From 810 dairy farms from which bulk milk samples were obtained during all three samplings, 146 (18.0%) farms were positive at one sampling date, 27 (3.3%) at two, and 4 (0.5%) on all three sampling dates. The majority of the farms represented in the study belonged to four districts of East Frisia, which showed no significant difference in the proportion of positive dairy farms.  相似文献   
52.
Oligoryzomys (Cricetidae, Sigmodontinae) is a common rodent genus from South America that includes a couple of very similar species. Related species have been used as experimental model for understanding several diseases for which these species are reservoirs. In order to provide a better understanding of the embryological aspects of this group, herein we showed data on the embryonic and fetal development in Oligoryzomys sp. Eight specimens of different stages of gestation were obtained from the Collection of the Zoology Museum of University of Sao Paulo, Brazil. Gestational ages were estimated by crown-rump-length according to Evans and Sack (1973). To address our analysis after examining the gross morphology, tissues from several organs were processed for light and scanning electron microscopy. Morphological data on the systems (nervous system, cardiorespiratory system, intestinal tract and urogenital system) were described in detail. Finally, the findings were compared with what is known about embryological aspects in other rodent species in order to establish similarities and differences during the organogenesis in different species.  相似文献   
53.
Wireworms, the polyphagous larvae of click beetles belonging to the genus Agriotes (Coleoptera: Elateridae), are severe and widespread agricultural pests affecting numerous crops. Biological control agents and methods for this general pest are highly solicited. In a screening for microbial Agriotes pathogens, an intracellular bacterium and a mitosporic fungus were isolated. Phylogenetic analysis based on ribosomal RNA operon sequences of both micro-organisms corroborated their previous morphology-based taxonomic classification. The bacterial pathogen has been assigned to the taxonomic genus Rickettsiella (Gammaproteobacteria) wherein it represents a new pathotype, ‘Rickettsiella agriotidis’, that appears most closely related to subjective synonyms of the nomenclatural type species, Rickettsiella popillae. The fungal pathogen has been shown to belong to the form-species Beauveria bassiana, i.e., an obligate anamorph related to the genus Cordyceps (Ascomycota: Hypocreales). Furthermore, the B. bassiana strain from Agriotes has been shown to be potentially susceptible to identification by gIi-diagnosis, i.e., a diagnostic method making use of the strain-specific presence of self-splicing group-I introns within the ribosomal RNA operons of certain hyphomycetous fungi.  相似文献   
54.
55.
Wheat powdery mildew(Blumeria graminis f.sp.tritici, Bgt) is a disease of increasing importance globally due to the adoption of high yielding varieties and modern sustainable farming technologies.Growing resistant cultivars is a preferred approach to managing this disease, and novel powdery mildew resistance genes are urgently needed for new cultivar development.A genome-wide association study was performed on a panel of 1292 wheat landraces and historical cultivars using 5011 single nucleotide polymorphism(SNP)markers.The association panel was evaluated for reactions to three Bgt inoculants, OKS(14)-B-3-1, OKS(14)-C-2-1, and Bgt15.Linkage disequilibrum(LD) analysis indicated that genome-wide LD decayed to 0.1 at 23 Mb, and population structure analysis revealed seven subgroups in the panel.Association analysis using a mixed linear model(MLM) identified three loci for powdery mildew resistance on chromosome 2 B, designated QPm.stars-2BL1,QPm.stars-2BL2, and QPm.stars-2BL3.To evaluate the efficacy of GWAS in gene discovery,QPm.stars-2BL2 was validated using F2 and F2:3 populations derived from PI420646 × OK1059060-126135-3.Linkage analysis delimited the powdery mildew resistance gene in PI 420646 to an interval where QPm.stars-2BL2 was located, lending credence to the GWAS results.QPm.stars-2BL1 and QPm.stars-2BL3, which were associated with four SNPs located at 457.7–461.7 Mb and two SNPs located at 696.6–715.9 Mb in the Chinese Spring reference IWGSC RefSeq v1.0, respectively, are likely novel loci for powdery mildew resistance and can be used in wheat breeding to improve powdery mildew resistance.  相似文献   
56.
57.
River corridor plants in Central Europe have in recent decades become increasingly rare, caused mainly by habitat destruction and change. The aim of this study was to examine the impact of soil quality, but especially of habitat fragmentation in terms of population size and isolation, on seed production and germination of five selected species, all of which being endangered, perennial herbs: Euphorbia palustris, Lathyrus palustris, Pseudolysimachion longifolium, Sanguisorba officinalis, and Senecio paludosus. We sampled totally 58 populations in flood plains in the surroundings of Bremen, North-western Germany.

In all five species, there were positive correlations between the number of seeds (total seed mass) and plant height, as well as between germination and seed mass. Seed traits values and/or germination were negatively affected by small population size, in Euphorbia, Lathyrus and Pseudolysimachion additionally by high population isolation. There were also significant effects of soil quality, but these were less consistent across species. The contribution of population size and isolation, compared to soil quality, to the variance explained in the reproductive components was especially high in Euphorbia and Lathyrus, the only two species depending on insect pollination.

The results indicate that the five species are likely to decline as a consequence of decreased plant fitness in small and/or isolated populations, probably caused by pollen limitation. The studied species may be representative for the group of river corridor plants as a whole that are often restricted to isolated remnants of near-natural flood plain vegetation in a matrix of heavily used agricultural land.  相似文献   

58.
Marine aquaculture facilities positioned far from the sea need access to seawater (SW); hence, commercial salts are often the chosen solution. In marine hatcheries, most fish larvae require live feed (zooplankton) that are in turn fed with microalgae. The objective of this research was to investigate the applicability of commercial salts and clarify the potential effects on the cultivation of the microalga Rhodomonas salina and the copepod Acartia tonsa. Three commercial salts were tested, Red Sea Salt (RS), Red Sea – Coral Pro Salt (CP), and Blue Treasure Salt. R. salina was cultured at salinities of 10, 20, and 30 psu resulting in equal growth rates at salinities 20 and 30 in SW and RS mixed with deionized (DI) water. The optimum salinity for R. salina was 29 psu. For A. tonsa eggs, we observed highest hatching success in 30 psu with CP or RS mixed with DI water. The egg hatching success was not affected by salinities 15–40 and optimal hatching was obtained at 27 psu. Results confirm it was possible to use commercial salts for rearing of both R. salina and A. tonsa, widening the application of these species for aquaculture facilities without access to SW.  相似文献   
59.
Streptococcus suis is a major cause of meningitis, sepsis and arthritis in piglets and a zoonotic agent. Survival in the blood circulation system represents a major step in pathogenesis of S. suis infections. To get further insights into the mechanisms of S. suis survival in the host, we compared a highly virulent S. suis serotype 2 strain with its non-encapsulated and suilysin-deficient mutants in their abilities to resist phagocytosis and killing by polymorphonuclear neutrophils (PMNs) and mononuclear cells. PMNs displayed a higher capacity to take up encapsulated bacteria than mononuclear cells, whereas both cell types internalized efficiently non-encapsulated S. suis. Differentiation of extracellular and intracellular survival of the WT strain revealed that in PMNs the majority of the cell-associated streptococci were intracellular, whereas in mononuclear cells the majority remained attached to the cell surface. S. suis survived mainly extracellularly, since both cells killed intracellular bacteria to a similar extent. As a consequence of different resistance to phagocytosis, only the encapsulated S. suis strains survived co-cultivation with PMNs. Comparison of the WT strain with its encapsulated suilysin-deficient mutant revealed reduced survival of the mutant after co-cultivation with PMNs. Involvement of suilysin in inhibition of phagocytosis was further confirmed by the use of anti-suilysin antibodies and recombinant suilysin. Kinetic experiments with PMNs suggested that reduced survival of the mutant strain was mainly associated with an increased uptake, whilst both strains adhered similarly. Concluding, our results indicate that the capsule and the suilysin play important roles in S. suis survival in the host by interfering with phagocytic uptake.  相似文献   
60.
A prion disease of cervids: chronic wasting disease   总被引:1,自引:0,他引:1  
Chronic wasting disease (CWD) is a prion disease of deer, elk, and moose, initially recognized in Colorado mule deer. The discovery of CWD beyond the borders of Colorado and Wyoming, in Canada and as far east as New York, has led to its emergence as a prion disease of international importance. Epidemiological studies indicate that CWD is horizontally transmitted among free-ranging animals, potentially indirectly by prion-containing secreta or excreta contaminating the environment. Experimental CWD transmission attempts to other wild and domestic mammals and to transgenic mice expressing the prion protein of cattle, sheep, and humans have shed light on CWD species barriers. Transgenic mice expressing the cervid prion protein have proven useful for assessing the genetic influences of Prnp polymorphisms on CWD susceptibility. Accumulating evidence of CWD pathogenesis indicates that the misfolded prion protein or prion infectivity seems to be widely disseminated in many nonneural organs and in blood. This review highlights contemporary research findings in this prion disease of free-ranging wildlife.  相似文献   
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