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161.
During the past two decades, the use of probiotics as an alternative to the use of antibiotics has shown to be promising in
aquaculture, particularly in fish and shellfish larviculture. This article reviews the studies on probiotics in larviculture,
focusing on the current knowledge of their in vivo mechanisms of action. The article highlights that the in vivo mechanisms
of action largely remain to be unravelled. Several methodologies are suggested for further in vivo research, including studies
on gut microbiota composition, the use of gnotobiotic animals as test models, and the application of molecular techniques
to study host–microbe and microbe–microbe interactions. 相似文献
162.
对大顶苦瓜感染白粉病的发病过程和生理机制进行研究。结果发现,感病苦瓜叶片质膜透性与对照相比增加较少,其增加量与病情指数相关性不高;叶绿素a、b、总叶绿素、类胡萝卜素含量随病情加重均下降,接种15d,与对照比分别下降72.6%、68.5%、71.5%和27.1%,其中叶绿素a、b和总叶绿素含量变化与病情指数相关性很高,以叶绿素a含量变化相关性最高;氧化酶活性测定结果表明,感病苦瓜叶片中POD和PPO活性与对照比上升,且随感病时间延长活性增加更多,接种15d,POD和PPO活性较对照增加528.5%和70.4%,两个酶活性变化与病情指数的相关性也很高。 相似文献
163.
164.
Aims: To evaluate the effectiveness of organic acids and supercritical carbon dioxide (SC-CO2 ) treatments as well as their combined effect for the reduction of nonpathogenic Escherichia coli and three pathogenic bacteria in fresh pork.
Methods and Results: The different treatment conditions were as follows: (i) treatment with acetic (1%, 2% or 3%) or lactic acid (1%, 2% or 3%) only, (ii) treatment with SC-CO2 at 12 MPa and 35°C for 30 min only and (iii) treatment with 3% acetic or lactic acid followed by treatment with SC-CO2 . Within the same organic acid concentration, the lactic and acetic acid treatments had similar reductions. For the combined treatment of lactic acid and SC-CO2 , micro-organism levels were maximally reduced, ranging from 2·10 to 2·60 log CFU cm−2 ( E. coli , 2·58 log CFU cm−2 ; Listeria monocytogenes , 2·60 log CFU cm−2 ; Salmonella typhimurium , 2·33 log CFU cm−2 ; E. coli O157:H7, 2·10 log CFU cm−2 ).
Conclusions: The results of this study indicate that the combined treatments of SC-CO2 and organic acids were more effective at destroying foodborne pathogens than the treatments of SC-CO2 or organic acids alone.
Significance and Impact of the Study: The combination treatment of SC-CO2 and organic acids may be useful in the meat industry to help increase microbial safety. 相似文献
Methods and Results: The different treatment conditions were as follows: (i) treatment with acetic (1%, 2% or 3%) or lactic acid (1%, 2% or 3%) only, (ii) treatment with SC-CO
Conclusions: The results of this study indicate that the combined treatments of SC-CO
Significance and Impact of the Study: The combination treatment of SC-CO
165.
Oxidation–reduction properties of surface sediments are tightly associated with the geochemistry of substances, and reducing
organic substances (ROS) from hydrophytes residues may play an important role in these processes. In this study, composition,
dynamics, and properties of ROS from anaerobic decomposition of Eichhornia crassipes (Mart.) Solms, Potamogenton crispus
Linn, Vallisneria natans (Lour.) Hara, Lemna trisulca Linn and Microcystis flos-aquae (Wittr) Kirch were investigated using differential pulse voltammetry (DPV). The type of hydrophytes determined both the reducibility and
composition of ROS. At the peak time of ROS production, the anaerobic decomposition of M. flos-aquae produced 6 types of ROS, among which 3 belonged to strongly reducing organic substance (SROS), whereas there were only 3–4
types of ROS from the other hydrophytes, 2 of them exhibiting strong reducibility. The order of potential of hydrophytes to
produce ROS was estimated to be: M. flos-aquae > E. crassipes > L. trisulca > P. crispus ≈ V. natans, based on the summation of SROS and weakly reducing organic substances (WROS). The dynamic pattern of SROS production was
greatly different from WROS. The total SROS appeared periodic fluctuation with reducibility gradually weakening with incubation
time, whereas the total WROS increased with incubation time. Reducibility of ROS from hydrophytes was readily affected by
acid, base and ligands, suggesting that their properties were related to these aspects. In addition to the reducibility, we
believe that more attention should be paid to the other behaviors of ROS in surface sediments. 相似文献
166.
167.
Rosa María Ramírez Yolanda Almanza Santos García Norma Heredia 《World journal of microbiology & biotechnology》2009,25(6):1019-1023
Avian septicemia is a systemic disease where bacteria attach and invade the avian respiratory tract and enter the bloodstream
and vital organs. Avian pathogenic Escherichia coli (APEC) cause this extraintestinal disease utilizing several virulence factors that have been identified. Adhesion to the
trachea is the critical initial step for septic APEC pathogenicity. We investigated the ability of APEC to associate with
models of tracheal epithelium. The microorganism was able to adhere to an avian tracheal explant model of infection. In addition,
a primary cell culture, derived from chicken tracheal epithelium, was developed and demonstrated the ability of APEC to attach
to and invade avian tracheal cells in vitro. These results are compatible with the nature of the disease and are important
to the understanding of the initial point of entry of APEC in the avian model of septic infections. 相似文献
168.
Syed Sultan Beevi Lakshmi Narasu Mangamoori Naveen Anabrolu 《World journal of microbiology & biotechnology》2009,25(3):465-473
Aqueous, methanol, ethyl acetate, and chloroform extracts of the root, stem, and leaf of Raphanus sativus were studied for antibacterial activity against food-borne and resistant pathogens. All extracts except the aqueous extracts
had significant broad-spectrum inhibitory activity. The ethyl acetate extract of the root had the potent antibacterial activity,
with a minimum inhibitory concentration (MIC) of 0.016–0.064 mg/ml and a minimum bactericidal concentration (MBC) of 0.016–0.512 mg/ml
against health-damaging bacteria. This was followed by the ethyl acetate extracts of the leaf and stem with MICs of 0.064–0.256
and 0.128–0.256 mg/ml, respectively and MBCs of 0.128–2.05 and 0.256–2.05 mg/ml, respectively. The ethyl acetate extracts
of the different parts of R. sativus retained their antibacterial activity after heat treatment at 100°C for 30 min, and their antibacterial activity was enhanced
when pH was maintained in the acidic range. Hence this study, for the first time, demonstrated that the root, stem, and leaf
of R. sativus had significant bactericidal effects against human pathogenic bacteria, justifying their traditional use as anti-infective
agents in herbal medicines. 相似文献
169.
Studies of genetic population structures of clonally reproducing macro-organisms have revealed large areas where only one clone is found. These areas, referred to as clonal patches, have not been shown to occur in free-living microbes until now. In free-living microbes, high genetic diversity at local scales is usually maintained by high rates of dispersal. We report, however, a highly dense, 12-m clonal patch of the social amoeba Dictyostelium discoideum in a cattle pasture located in a Texas Gulf Coast prairie. We confirm the presence of only one clone by the analysis of 65 samples and amplification of 10 polymorphic microsatellite loci. Samplings of additional cattle pastures nearby showed higher clonal diversity, but with a density of D. discoideum isolates lower than in the clonal patch. These findings show that high rates of microbial dispersal do not always produce genetic diversity at local scales, contrary to the findings of previous studies. The existence of clonal patches may be particularly important for microbial social evolution. 相似文献
170.
禽源致病性大肠埃希菌的耐药性与中草药有效成分的抑菌活性测定 总被引:1,自引:0,他引:1
以28株合肥地区禽源致病性大肠埃希菌为实验材料,采用K-B纸片琼脂扩散法检测禽源致病性大肠埃希菌的耐药情况。同时采用平板打孔法测定盐酸小檗碱、绿原酸、靛玉红和丹参酮ⅡA 4种中草药有效成分的抑菌活性。结果表明,28株禽源致病性大肠埃希菌对17种抗菌药物均呈现不同程度的耐药性,对β-内酰胺类、氨基糖苷类、四环素类和喹诺酮类抗菌药物的耐药率分别介于0%~92.86%、14.29%~50.00%、78.57%~100%和57.14%~71.43%。中草药有效成分盐酸小檗碱和丹参酮ⅡA对大肠埃希菌具有较好的抑制活性,抑菌率分别为92.86%(26/28)和89.29%(25/28)。 相似文献