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991.
Isolate 3.1T8 of Lysobacter enzymogenes (Christensen and Cook 1978), originating from the rhizosphere of cucumber and shown to have the potential to control Pythium aphanidermatum, is described. The strain produces extracellular proteases and lipases and shows high levels of resistance against streptomycin, kanamycin and tetracycline, but not to chloramphenicol. It shows strong in vitro antibiosis against P. aphanidermatum and several other phytopathogenic fungi. In order to identify the isolate, a carbon substrate oxidation profile (Biolog) was generated, and fatty acid methyl ester (FAME) analysis was performed. Also, the 16S rRNA gene was cloned and sequenced. With Biolog and FAME analysis, no assignment to species level was possible, because the species was not in the respective databases. BLAST analysis of the obtained sequence, followed by phylogenetic analysis, using a number of related and unrelated sequences, showed that the isolate was most closely related to Lysobacter enzymogenes (Christensen and Cook 1978). 相似文献
992.
ABSTRACT Population growth for mallards (Anas platyrhynchos), and presumably other upland nesting ducks, in the Prairie Pothole Region of the United States and Canada is most sensitive to nest success, and nest success is most strongly influenced by predation. We evaluated the efficacy of reducing predator populations to improve nest success of upland nesting ducks on township-sized (93.2 km2) management units in eastern North Dakota, USA, during 2005–2007. We monitored 7,489 nests on 7 trapped and 5 nontrapped sites. Trappers annually removed an average of 245 predators per trapped site, and we found nest success to be 1.4–1.9 times greater on trapped sites than nontrapped sites, depending on year. Nest success was greater on both trapped and nontrapped sites when compared with a study conducted in the same areas in the mid-1990s, likely because of changes in red fox (Vulpes vulpes) and coyote (Canis latrans) population dynamics. Nests initiated midseason had higher daily survival rates (DSR) than those initiated earlier or later in the season. Daily survival rates for nests in the middle of the nesting cycle were higher than for nests that were early in laying or late in incubation. Nests near the periphery of trapped sites had slightly higher DSRs than nests in the center of trapped sites. Predator reduction at the township scale provides managers with an effective tool to improve nest success at large spatial scales. 相似文献
993.
Trees from the genus Boswellia (Burseraceae) are traditionally used as a medicine, a fumigant, in various cosmetic formulations and in aromatherapy in several countries around the world. This plant produces a commercial oil known as frankincense which has a woody, spicy and haunting smell. Frankincense oil has several pharmacological properties, of which many elude to the anti-infective potential. Variation in the chemical composition of this oil has been reported in literature. These factors prompted an investigation to study the commercial frankincense oils from various international suppliers. Twenty essential oils were analyzed by gas chromatography coupled to mass spectrometry. Considering the major constituents, the oils were found to be qualitatively similar. However, there was immense quantitative variation for certain oil constituents. The components identified and their range in the oils include α-pinene (2.0–64.7%); α-thujene (0.3–52.4%); β-pinene (0.3–13.1%); myrcene (1.1–22.4%); sabinene (0.5–7.0%); limonene (1.3–20.4%); p-cymene (2.7–16.9%) and β-caryophyllene (0.1–10.5%). The antimicrobial activity (minimum inhibition concentration assay) of the oils was investigated against five reference test organisms and the activity ranged from 4–16 mg/ml (Staphylococcus aureus); 1.5–8.3 mg/ml (Bacillus cereus); 4.0–12.0 mg/ml (Escherichia coli); 2.0–12.8 mg/ml (Proteus vulgaris) and 5.3–12.0 mg/ml (Candida albicans). 相似文献
994.
Fopius arisanus (Sonan), a solitary koinobiont endoparasitoid of fruit flies, was introduced for testing and final release against the recently discovered species Bactrocera invadens Drew, Tsuruta and White in Africa. Laboratory experiments were conducted to assess host preference, host acceptability for oviposition, and physiological suitability of B. invadens and five other indigenous tephritid fruit fly species, namely, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), C. cosyra (Walker), C. rosa Karsch, C. fasciventris (Bezzi), and C. anonae Graham. Females of F. arisanus visited all host egg patches, but showed a stronger preference to eggs of B. invadens, which was also most accepted for oviposition. Successful development of parasitoid progenies varied greatly across hosts, with B. invadens yielding the highest parasitoid progeny and C. fasciventris yielding no F. arisanus progeny. Most of the parasitoid eggs laid in C. rosa and C. fasciventris were encapsulated. Sex ratio was not influenced by host species and it was female biased in all hosts that produced parasitoid progeny. Fopius arisanus was able to establish a new association with C. capitata, C. cosyra and to a lesser extent C. anonae. The results are discussed in the light of the potential use of F. arisanus as a biological control agent of B. invadens. 相似文献
995.
M.A. Golowczyc J. Silva A.G. Abraham G.L. De Antoni P. Teixeira 《Letters in applied microbiology》2010,50(1):7-12
Aims: This work aims to investigate the survival of Lactobacillus kefir CIDCA 8348, Lactobacillus plantarum CIDCA 83114 and Saccharomyces lipolytica CIDCA 812, all isolated from kefir, during spray drying and subsequent storage.
Methods and Results: Micro-organisms were grown in De Man, Rogosa, Sharpe (MRS) or yeast medium (YM) medium and harvested in the stationary phase of growth. The thermotolerance in skim milk ( D and Z values), the survival of spray drying at different outlet air temperatures and subsequent storage in different conditions during 150 days were studied. The resistance to the heat treatments was higher in Lact. plantarum compared to Lact. kefir and S. lipolytica . The three micro-organisms studied varied considerably in their ability to survive to spray drying processes . Lactobacillus plantarum showed the highest survival rate for all the tested outlet air temperatures and also to the further storage in the dried state. The survival rates of Lact. kefir and S. lipolytica through drying and subsequent storage in the dried state decreased when the drying outlet air temperatures increased.
Conclusions: Spray drying is a suitable method to preserve micro-organisms isolated from kefir grains. A high proportion of cells were still viable after 80 days of storage at refrigerated temperatures
Significance and Impact of Study: It is the first report about spray-dried probiotic strains isolated from kefir grain and contributes to the knowledge about these micro-organisms for their future application in novel dehydrated products. 相似文献
Methods and Results: Micro-organisms were grown in De Man, Rogosa, Sharpe (MRS) or yeast medium (YM) medium and harvested in the stationary phase of growth. The thermotolerance in skim milk ( D and Z values), the survival of spray drying at different outlet air temperatures and subsequent storage in different conditions during 150 days were studied. The resistance to the heat treatments was higher in Lact. plantarum compared to Lact. kefir and S. lipolytica . The three micro-organisms studied varied considerably in their ability to survive to spray drying processes . Lactobacillus plantarum showed the highest survival rate for all the tested outlet air temperatures and also to the further storage in the dried state. The survival rates of Lact. kefir and S. lipolytica through drying and subsequent storage in the dried state decreased when the drying outlet air temperatures increased.
Conclusions: Spray drying is a suitable method to preserve micro-organisms isolated from kefir grains. A high proportion of cells were still viable after 80 days of storage at refrigerated temperatures
Significance and Impact of Study: It is the first report about spray-dried probiotic strains isolated from kefir grain and contributes to the knowledge about these micro-organisms for their future application in novel dehydrated products. 相似文献
996.
Parasites as indicators of individual feeding specialization in Arctic charr during winter in northern Norway 总被引:2,自引:0,他引:2
The relationship between infection with the food-transmitted parasites Diphyllobothrium dendriticum, D. ditremum (Cestoda) and Cystidicola farionis (Nematoda) and prey selection was studied in individual Arctic charr from Lake Takvatn, northern Norway. There was no correlation between parasites transmitted throughout prey organisms from benthic habitats (amphipods) and pelagic habitats (copepods). A strong relationship between infection with a parasite species and the corresponding intermediate host from the stomach content of individual charr, indicated an individual feeding specialization. Independent of size, charr specialized on the intermediate hosts of all three parasite species. Some charr maintained this specialization on specific prey items throughout the winter period. These parasite species are considered to be useful indicators of past prey selection. 相似文献
997.
Jens P. Levenfors Thomas H. Eberhard Jolanta J. Levenfors Berndt Gerhardson Margareta Hökeberg 《BioControl》2008,53(4):651-665
Seed lots of winter wheat and rye, naturally infested with Microdochium nivale and Fusarium spp., were treated with an isolate of Pseudomonas, which was recovered from roots of Brassica napus. Seeds were treated with bacterial fermentate and dried before sowing or they were directly sprayed in the furrow-opener
at the moment of sowing. Besides field experiments, parallel climate chamber bioassays were performed to assess the effect
of bacterial treatment on snow mould caused by seed-borne M. nivale and Fusarium spp. The biocontrol effect was assessed by plant density counts and by measuring yield. Significant biocontrol activity,
measured by plant density counts, was detected both in field and climate chamber experiments sown with wheat. Biocontrol effect
after spray application at sowing was less pronounced, although a slight increase in plant density was observed. The cell
concentration required to obtain adequate biocontrol effect was 109 CFU per ml for the dose used. The bacterial isolate was identified by 16S rDNA sequencing and biochemical tests as a Pseudomonas brassicacearum strain. 相似文献
998.
M. C. Gross C. H. Schneider G. T. Valente C. Martins E. Feldberg 《Journal of fish biology》2010,76(5):1117-1127
Three species of cichlids belonging to the genus Symphysodon have demonstrated interspecific and intraspecific variation in nucleolus organizer regions (NOR) detected with silver nitrate. In order to understand the evolution of this marker in the genus, the structural variability of these sequences in mitotic chromosomes from Symphysodon aequifasciatus, Symphysodon discus and Symphysodon haraldi was investigated using both silver nitrate impregnation and hybridization of the 18S rRNA gene probe. For the three species, the two markers were intraspecifically and interspecifically variable both in the number and in the size of the sites. This polymorphism may stem from duplications and translocations, which suggests that structural chromosome rearrangements effectively act in the karyoevolution of wild Symphysodon species and may have favoured the adaptability of these fishes to diverse aquatic environments in the Amazon. 相似文献
999.
Agriculturally important grasses such as sugar cane (Saccharum sp.), rice (Oryza sativa), wheat (Triticum aestivum) sorghum (Sorghum bicolor), maize (Zea mays), Panicum maximum, Brachiaria spp., and Pennisetum purpureum contain numerous diazotrophic bacteria, such as, Acetobacter diazotrophicus, Herbaspirillum spp., Azospirillum spp. These bacteria do not usually cause disease symptoms in the plants with which they are associated and the more numerous of them, for example, Herbaspirillum spp. and A. diazotrophicus, are obligate or facultative endo-phytes that do not survive well (or at all) in native soil; these are thought to be spread from plant generation to plant generation via seeds, vegetative propagation, dead plant material, and possibly by insect sap feeders. By contrast, Azospirillum spp. are not wholly endophytic but are root-associated, soil-dwelling bacteria that are also often found within plants, probably entering host plants via seeds or via wounds/cracks at lateral root junctions. Endophytic diazotrophs have been isolated from a number of grasses in which significant biological N2 fixation (BNF) has been demonstrated, particularly Brazilian sugar cane varieties, but also in rice, maize, and sorghum. However, although the endophytic diazotrophs are held to be the causative agents of the observed BNF, direct evidence for this is lacking. Therefore, in this review we examine probable sites of bacterial multiplication and/or BNF within endophyte-containing grasses and discuss these in terms of potential benefits (or not) to both host plants and bacteria. In particular, we examine how potentially large numbers of bacteria, especially Herbaspirillum spp., A. diazotrophicus, and Azospirillum spp., can exist extracellularly within non-specialized (for symbiotic purposes) regions such as xylem vessels and intercellular spaces. The processes of infection and colonization of various grasses (particularly sugar cane) by diazotrophic endophytes are also described, and these are compared with those of important (nondiazotrophic) endophytic sugar cane pathogens such as Clavibacter xyli subsp. xyli and Xanthomonas albilineans. 相似文献
1000.