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971.
972.
为了发现阴生植物越过强光和高温的光合机制,采用LI-6400光合测定系统和石蜡切片法,对虎耳草的春叶和秋叶的光合生理和叶片结构进行了研究。结果表明:春叶的光合速率、气孔导度等极显著低于秋叶,光合速率的降低受气孔因子限制;通过Pn-PAR曲线方程发现,春叶的补偿点为14.3 μmol photons/(m2?s),光饱和点为346 μmol photons/(m2?s),均极显著高于秋叶,表明春叶对强光有较好的耐受性;叶片解剖结构表明,春叶叶肉组织增加极显著,但栅海比低于秋叶,这证实了不同叶龄虎耳草叶片形态结构与生理功能的一致性。 相似文献
973.
Zoospore-producing oomycetes are major plant pathogens of particular concern in hydroponic systems. Compared with pesticides, biocontrol using antagonistic microorganisms is a sustainable approach to control oomycetes. Previous research has demonstrated that biosurfactants and biosurfactant-producing microorganisms are potentially useful components of a sustainable biocontrol strategy.In this study three ways of supplying a biosurfactant-producing strain to a recirculating hydroponic cultivation system infected with a zoospore-producing plant pathogen were evaluated. The strain Pseudomonas koreensis 2.74 was added as washed cells, in its spent KB broth or in a minimal medium adapted from the nutrient solution, and compared with control treatments. A significant reduction in disease with up to 50% was achieved when a high concentration of washed cells was added weekly to the plant cultivation system. The disease suppression obtained through addition of washed cells equalled the effect achieved when the purified biosurfactant was used. Phytotoxicity was observed when the spent broth was included in the treatment. 相似文献
974.
Apparent amylose content is a key element for characterizing a rice (Oryza sativa L.) cultivar for cooking quality. However, cultivars with similar apparent amylose content can have widely varying quality attributes, including major parameters of flour paste viscosity. It has been postulated that the presence of a rice Waxy gene single nucleotide polymorphism (SNP) marker is associated with elevated Rapid Visco Analyser (RVA) properties in specific high amylose rice cultivars. A mapping population derived from a cross between two varieties, Cocodrie and Dixiebelle, having similar high apparent amylose contents, but with different paste viscosity properties and Waxy gene markers was analyzed for the genetic segregation of various pasting properties, measured with RVA instrumentation. Marker inheritance analyses revealed that the Waxy exon 10 SNP marker was associated with the proportion of soluble to insoluble apparent amylose and most RVA pasting measurements. Waxy gene markers can be used to efficiently improve the selection of rice with desirable characteristics, particularly for superior parboiling and canning quality. 相似文献
975.
Pasquale Chiaiese Gianluca Ruotolo Antonio Di MatteoAmalia De Santo Virzo Anna De MarcoEdgardo Filippone 《Industrial Crops and Products》2011,34(1):1072-1078
In order to apply state-of-the-art molecular breeding techniques in fibre crop it is necessary to have a good knowledge of major polymer biosynthesis gene sequences and their expression pattern. Polymerase chain reaction was employed to isolate sequences of the major genes for lignin and cellulose biosynthesis in a kenaf cultivar. CeSA, 4cl, c4h, cad, and ccr gene primers were designed according to their conservative regions; partial sequences of lignin and cellulose biosynthesis genes were obtained. One actin II gene sequence was also isolated from the kenaf genome as a housekeeping gene to be employed in qPCR analysis. Expression levels of genes c4h, cad and CeSA in bark and core from plants harvested at three different growth stages were evaluated. Using qPCR analyses it was found that the expression levels of the two biosynthesis lignin genes in bark tissues increased during plant growth, while a negative trend was recorded in core tissues. In both bark and core, the quantity of lignin was positively correlated to plant growth while cellulose content decreased. 相似文献
976.
Marianne Iversen Anne Ingeborg Myhr Anna Wargelius 《Journal Of Applied Aquaculture》2013,25(4):330-369
ABSTRACTThe aquaculture industry is under pressure to satisfy global demand for marine foods. Atlantic salmon has been bred for more than 40 years, and substantial progress has been made within the culturing and breeding programs. The improved growth rate of Atlantic salmon has been accompanied by an earlier onset of maturation. Among the factors controlling maturation in salmon are photoperiod, temperature, and body composition. Early sexual maturation is detrimental to fish health and quality when viewed from an aquacultural viewpoint. There are several approaches for alleviating this problem: (1) traditional selection, (2) manipulation of external factors affecting puberty (e.g., light), (3) novel biotechnological methods for improving breeding methods, (4) induction of polyploidy, and (5) genetic modification controlling maturation. This article presents the ecological and ethical issues connected to these approaches and argues the importance of acknowledging and discussing such issues in order to ensure that all stakeholder concerns are considered. 相似文献
977.
Sieroslawska A Rymuszka A Velisek J Pawlik-Skowrońska B Svobodova Z Skowroński T 《Fish physiology and biochemistry》2012,38(4):1159-1167
The aim of the study was to assess the effects of a cyanobacterial extract containing microcystins (MCs) on selected hematological and biochemical parameters in common carp (Cyprinus carpio L.), as well as to determine the accumulation of toxins in fish tissues. The fish were immersed for 5 days in water containing toxins at a final concentration of 12 μg/L of microcystin LR equivalent. Microcystin LR residues were detected in fish liver, reaching 207, 238 and 260 ng/g f.w. of the tissues taken 24 h, 72 h and 5 days after the end of intoxication, respectively. The most substantial changes were found in fish plasma, including increases in creatine kinase, lactate dehydrogenase, ammonia, glucose, aspartate aminotransferase and alanine aminotransferase levels. A decline of about 50% in lysozyme activity was observed by the end of the experimental period. Moreover, a marked increase in ceruloplasmin activity was detected 24 h after the end of intoxication with a subsequent decrease in its activity after 72 h and 5 days. This study concludes that not only consumption of food containing toxins but also MCs dissolved in water may pose a threat to fish health. Additionally, detected changes in lysozyme and ceruloplasmin activity may have distinct effects in fish resistance against pathogens or oxidative stress, which should be taken into account in the future studies. 相似文献
978.
Paul C Reunamo A Lindehoff E Bergkvist J Mausz MA Larsson H Richter H Wängberg SÅ Leskinen P Båmstedt U Pohnert G 《Marine drugs》2012,10(4):775-792
Several marine and freshwater diatoms produce polyunsaturated aldehydes (PUA) in wound-activated processes. These metabolites are also released by intact diatom cells during algal blooms. Due to their activity in laboratory experiments, PUA are considered as potential mediators of diatom-bacteria interactions. Here, we tested the hypothesis that PUA mediate such processes in a close-to-field mesocosm experiment. Natural plankton communities enriched with Skeletonema marinoi strains that differ in their PUA production, a plankton control, and a plankton control supplemented with PUA at natural and elevated concentrations were observed. We monitored bacterial and viral abundance as well as bacterial community composition and did not observe any influence of PUA on these parameters even at elevated concentrations. We rather detected an alternation of the bacterial diversity over time and differences between the two S. marinoi strains, indicating unique dynamic bacterial communities in these algal blooms. These results suggest that factors other than PUA are of significance for interactions between diatoms and bacteria. 相似文献
979.
Pistocchi R Guerrini F Pezzolesi L Riccardi M Vanucci S Ciminiello P Dell'Aversano C Forino M Fattorusso E Tartaglione L Milandri A Pompei M Cangini M Pigozzi S Riccardi E 《Marine drugs》2012,10(1):140-162
The Northern Adriatic Sea is the area of the Mediterranean Sea where eutrophication and episodes related to harmful algae have occurred most frequently since the 1970s. In this area, which is highly exploited for mollusk farming, the first occurrence of human intoxication due to shellfish consumption occurred in 1989, nearly 10 years later than other countries in Europe and worldwide that had faced similar problems. Until 1997, Adriatic mollusks had been found to be contaminated mostly by diarrhetic shellfish poisoning toxins (i.e., okadaic acid and dinophysistoxins) that, along with paralytic shellfish poisoning toxins (i.e., saxitoxins), constitute the most common marine biotoxins. Only once, in 1994, a toxic outbreak was related to the occurrence of paralytic shellfish poisoning toxins in the Adriatic coastal waters. Moreover, in the past 15 years, the Adriatic Sea has been characterized by the presence of toxic or potentially toxic algae, not highly widespread outside Europe, such as species producing yessotoxins (i.e., Protoceratium reticulatum, Gonyaulax spinifera and Lingulodinium polyedrum), recurrent blooms of the potentially ichthyotoxic species Fibrocapsa japonica and, recently, by blooms of palytoxin-like producing species of the Ostreopsis genus. This review is aimed at integrating monitoring data on toxin spectra and levels in mussels farmed along the coast of the Emilia-Romagna region with laboratory studies performed on the species involved in the production of those toxins; toxicity studies on toxic or potentially toxic species that have recently appeared in this area are also reviewed. Overall, reviewed data are related to: (i) the yessotoxins producing species P. reticulatum, G. spinifera and L. polyedrum, highlighting genetic and toxic characteristics; (ii) Adriatic strains of Alexandrium minutum, Alexandrium ostenfeldii and Prorocentrum lima whose toxic profiles are compared with those of strains of different geographic origins; (iii) F. japonica and Ostreopsis cf. ovata toxicity. Moreover, new data concerning domoic acid production by a Pseudo-nitzschia multistriata strain, toxicity investigations on a Prorocentrum cf. levis, and on presumably ichthyotoxic species, Heterosigma akashiwo and Chattonella cf. subsalsa, are also reported. 相似文献
980.