全文获取类型
收费全文 | 1142篇 |
免费 | 61篇 |
国内免费 | 1篇 |
专业分类
林业 | 26篇 |
农学 | 31篇 |
基础科学 | 5篇 |
100篇 | |
综合类 | 67篇 |
农作物 | 19篇 |
水产渔业 | 35篇 |
畜牧兽医 | 763篇 |
园艺 | 12篇 |
植物保护 | 146篇 |
出版年
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 8篇 |
2020年 | 12篇 |
2019年 | 10篇 |
2018年 | 27篇 |
2017年 | 20篇 |
2016年 | 17篇 |
2015年 | 17篇 |
2014年 | 25篇 |
2013年 | 102篇 |
2012年 | 56篇 |
2011年 | 52篇 |
2010年 | 20篇 |
2009年 | 24篇 |
2008年 | 67篇 |
2007年 | 55篇 |
2006年 | 49篇 |
2005年 | 50篇 |
2004年 | 51篇 |
2003年 | 38篇 |
2002年 | 31篇 |
2001年 | 40篇 |
2000年 | 40篇 |
1999年 | 30篇 |
1998年 | 19篇 |
1997年 | 7篇 |
1996年 | 11篇 |
1995年 | 10篇 |
1994年 | 18篇 |
1993年 | 10篇 |
1992年 | 25篇 |
1991年 | 36篇 |
1990年 | 26篇 |
1989年 | 27篇 |
1988年 | 15篇 |
1987年 | 12篇 |
1986年 | 20篇 |
1985年 | 17篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1977年 | 5篇 |
1975年 | 5篇 |
1974年 | 10篇 |
1971年 | 4篇 |
1929年 | 4篇 |
排序方式: 共有1204条查询结果,搜索用时 15 毫秒
31.
A. Tempel J. Meltzer B. G. van den Bos 《European journal of plant pathology / European Foundation for Plant Pathology》1968,74(5):133-139
The compounds referred to in the title have been investigated for fungicidal, insecticidal and acaricidal activities in laboratory and greenhouse tests. Several representatives of this class of compounds were active against powdery mildew on apple, cucumber, and barley, and against aphids and spider mites, both when applied to the leaves and when added to the nutrient solutions of test plants. Treatment of leaf halves resulted in protection of the entire leaves. A striking difference in pesticidal activity was observed between two series of isomers. Representatives of the series with the phosphoryl group in the 1-position showed much greater pesticidal activities than their corresponding isomers with the phosphoryl group in the 2-position. The optimum activity within the two homologous series (R-H, CH3 ... C6H13) was determined: generally the lower homologues (R-H, CH3, C2H5 and i-C3H7) showed the greatest pesticidal activity in the systemic tests. After leaf-application the influence of the length of R was less pronounced or even reversed.Samenvatting De in de titel genoemde stoffen zijn onderzocht op fungicide, insecticide en acaricide werking in laboratorium en kasproeven. Verscheidene vertegenwoordigers van dit type verbindingen waren werkzaam tegen echte meeldauw van appel, komkommer en gerst, en tegen bladluizen en spint, dit zowel na toepassing op de bladeren als na toevoeging aan de voedingsoplossingen van proefplanten. Behandeling van bladhelften resulteerde in bescherming van de gehele bladeren. Een opvallend verschil werd waargenomen tussen de werking van twee reeksen isomeren. Vertegenwoordigers van de reeks met de fosforylgroep op de 1-plaats waren veel werkzamer dan hun isomeren met de fosforylgroep op de 2-plaats. Het optimum binnen de twee homologe reeksen (R-H, CH3 ... C6H13) werd bepaald: in het algemeen waren de lagere homologen (R-H, CH3; C2H5 en i-C3H7) het werkzaamst in de systemische proeven. Na een preventieve bladbespuiting was de invloed van de lengte van R minder uitgesproken of zelfs omgekeerd. 相似文献
32.
Breugelmans S De Spiegelaere W Casteleyn C Simoens P Van den Broeck W 《Comparative immunology, microbiology and infectious diseases》2011,34(3):217-225
In sheep, the pharyngeal first defence line against oral and inhaled antigens is organized in six tonsils. Since tonsils are regarded as secondary lymphoid tissue and part of the acquired immune system which is subjected to induction through contact with antigens, an evaluation of the different lymphocyte populations in tonsils is useful to determine a tendency of the specific tonsils to more inductive or more effective immunity. By means of immunohistochemistry, different lymphocyte populations were quantified and localized using a panel of eight antibodies, i.e. anti-CD45, anti-CD21, anti-CD2, anti-CD3, anti-CD4, anti-CD8, anti-WC1 and anti-Ki67. The CD21+ B lymphocytes were localized within the tonsillar lymphoid follicles. The CD2+/CD3+ T lymphocytes were numerous in the interfollicular regions and were aligned underneath and within the epithelium but were also observed at the CD21+ pole of the lymphoid follicles. Near the lingual and tubal tonsils, and the tonsil of the soft palate, the CD45+ cells around the seromucous glands and in the lamina propria were mainly CD3+ T cells. In all tonsils, the WC1+ gamma delta T cells formed a small lymphocyte population which harboured the lamina propria and the interfollicular region. The relative percentages of the different lymphocyte populations of the large palatine and pharyngeal tonsils, which are macroscopically the most developed, were comparable. In contrast, the lingual tonsil was significantly different from the other tonsils not only by its small size and lack of lymphoid follicles, but also by the lymphocyte populations. Based on the lymphocyte populations, the ovine tonsils can be divided in three groups with the tonsil of the soft palate, the tubal and paraepiglottic tonsil forming an intermediate between the palatine and pharyngeal tonsils as true tonsils on the one side, and the lingual tonsil as a scattered lymphocyte aggregation on the other side. 相似文献
33.
Huntley JF van den Broek A Machell J Mackellar A Pettit D Meikle L Barcham G Meeusen EN Smith D 《Veterinary parasitology》2005,127(3-4):323-332
The present study confirms that following infection with the ectoparasitic sheep scab mite, Psoroptes ovis, there is a rapid (within 24 h) inflammatory influx of eosinophils and apoptosis of the keratinocytes at the site of infection. In order to investigate whether these inflammatory reactions are important in the maintenance of mite infection, a group of animals were treated daily after the establishment of infection with the potent anti-inflammatory drug, Cyclosporin A. The course of infection was monitored by determining the lesion area and mite numbers, systemic antibody and blood eosinophils, as well as the inflammatory cells and T cell sub-populations within the lesion throughout the 6-week duration of the experiment. These parameters were compared with those in a similar infected control (non-treated) group. In control infected animals, the lesion area and mite numbers increased steadily throughout the 6-week period. In contrast, lesion area and mite numbers were severely depressed in the group which received Cyclosporin A. Local and systemic eosinophils, and systemic antibody were also significantly reduced in the drug treated animals, compared to controls. Surprisingly however, the number of lesional pan T cells, T helper cells, gammadeltaT cells and dendritic cells in Cyclosporin A treated animals were either the same, or significantly (P < 0.05) enhanced when compared to the control infected animals at the termination of the experiment. The results will be discussed in terms of the role of the dermal inflammatory response in the establishment and maintenance of the sheep scab mite. 相似文献
34.
van Klaveren NJ Suwankong N De Boer S van den Brom WE Voorhout G Hazewinkel HA Meij BP 《Veterinary surgery : VS》2005,34(5):450-456
OBJECTIVE: Using force plate analysis (FPA), determine ground reaction forces in dogs with degenerative lumbosacral stenosis (DLS) and evaluate the effects of lumbosacral decompressive surgery. STUDY DESIGN: Prospective clinical study. ANIMALS: Twelve dogs with DLS. METHODS: DLS was diagnosed by clinical signs, radiography, computed tomography, and/or magnetic resonance imaging. FPA was performed before surgery, and 3 days, 6 weeks, and 6 months after surgery. The mean peak braking (Fy+), peak propulsive (Fy-), and peak vertical (Fz+) forces of 8 consecutive strides were determined. The ratio between the total Fy- of the pelvic limbs and the total Fy- of the thoracic limbs (P/TFy-), reflecting the distribution of Fy-, was analyzed to evaluate any changes in locomotion pattern postoperatively. Ground reaction force data for DLS dogs were compared with data derived from 24 healthy dogs (control). RESULTS: In dogs with DLS, the propulsive forces (Fy-) of the pelvic limbs were significantly smaller than those of controls. P/TFy- was significantly smaller in dogs with DLS than in control dogs, and increased during the follow-up period, reaching normal values 6 months after surgery. CONCLUSIONS: Cauda equina compression in dogs with DLS decreases the propulsive force of the pelvic limbs and surgical treatment restores the propulsive force of the pelvic limbs in a 6-month period. CLINICAL RELEVANCE: In dogs with DLS, FPA is an effective method in evaluating the response to surgical treatment. Normal propulsive force in the pelvic limbs was restored during 6 months after decompressive surgery. 相似文献
35.
36.
Hambrecht E Eissen JJ Newman DJ Smits CH Verstegen MW den Hartog LA 《Journal of animal science》2005,83(4):900-907
The objective of the present experiment was to investigate the effects of transportation, lairage, and preslaughter stressor treatment on glycolytic potential and pork quality of the glycolytic longissimus and the oxidative supraspinatus (SSP) or serratus ventralis (SV) muscles. In a 2 x 2 x 2 factorial design, 384 pigs were assigned randomly either to short (50 min) and smooth or long (3 h) and rough transport, long (3 h) or short (< 45 min) lairage, and minimal or high preslaughter stress. Muscle samples were taken from the LM at 135 min and from the SSP at 160 min postmortem for determination of the glycolytic potential and rate of glycolysis. At 23 h postmortem, pork quality was assessed in the LM and the SV. Effects of transport and lairage conditions were similar in both muscle types. Long transport increased (P < 0.01) the glycolytic potential and muscle lactate concentrations compared with short transport. Both long transportation and short lairage decreased (P < 0.01) redness (a* values) and yellowness (b* values) of the LM and SV. In combination with short lairage, long transport decreased (P < 0.05) pork lightness (lower L* values), and electrical conductivity was increased (P < 0.05) after long transport. Several interactions between stress level and muscle type (P < 0.001) were observed. High preslaughter stress decreased (P < 0.001) muscle glycogen in both the LM and SSP, but this decrease was greater in the LM. Lactate concentrations were increased (P < 0.001) only in the LM by high preslaughter stress. Increases in ultimate pH (P < 0.001) and decreases in a* values (P < 0.01) were greatest in the SV, whereas increases in electrical conductivity (P < 0.001) were greatest in the LM. The lack of interactions among transportation, lairage, and muscle type was attributed to the relatively minor differences in stress among treatments. It was concluded that, in glycolytic muscle types such as the LM, the high physical and psychological stress levels associated with stress in the immediate preslaughter period have a greater effect on the water-holding capacity of the meat and may promote PSE development. Conversely, oxidative muscle types tend to have higher ultimate pH values and produce DFD pork in response to intense physical activity and/or high psychological stress levels preslaughter. 相似文献
37.
Douglas fir (Pseudotsuga menziessi [Mirb.] Franco) seedlings from a half diallel mating design showed significant family by nutrient interactions when grown
in a 3N × 3P × 15 family factorial experiment for 2 yr. Differences in response of these families to N and P treatment levels
were related to nutrient productivity (dry matter production nutrient−1 time−1), but unrelated to the proportion of dry matter allocated to root growth, or to nutrient net uptake rate. Significance of
general combining ability for N and K productivity showed clonal control of these characters. Evidence for genetic control
of tissue N% and K%, shoot:root ratio and N uptake rate were also shown. 相似文献
38.
P. H. J. F. van den Boogert T. A. W. M. Saat 《European journal of plant pathology / European Foundation for Plant Pathology》1991,97(2):115-124
Sclerotia ofRhizoctonia solani collected from potato tubers from different countries were assayed for the presence of mycoparasites. Among the mycoparasites observedVerticillium biguttatum predominated. Its geographical distribution was not restricted to certain latitudes or soil types;V. biguttatum occurred worldwide in potato fields.The minimum growth temperature of 57V. biguttatum isolates was found to be in the narrow range from 10 to 13°C, irrespective of their geographical origin. A non-linear logistic growth model was used to describe the radial growth onRhizoctonia mycelium and nutrient agar plates. At near-minimum temperature the maximum colony radii varied considerably; they were up to 3.8 times that of the reference isolate M73. Based on parameter values for logistic growth, fast-and slow-growing isolates could be distinguished. Although the growth properties ofV. biguttatum isolates from different locations varied, the presence of fast- and slow-growing isolates was not restricted to particular areas and both types could be found in the same field. However, bioassays with selected fast- and slow-growing isolates do not support the assumption that growth at near-minimum temperatures is a relevant criterion for screening isolates ofV. biguttatum in terms of effectiveness for biological control ofR. solani. 相似文献
39.
40.