全文获取类型
收费全文 | 487篇 |
免费 | 6篇 |
专业分类
林业 | 4篇 |
农学 | 3篇 |
基础科学 | 2篇 |
47篇 | |
综合类 | 135篇 |
农作物 | 5篇 |
水产渔业 | 28篇 |
畜牧兽医 | 164篇 |
植物保护 | 105篇 |
出版年
2021年 | 5篇 |
2020年 | 5篇 |
2013年 | 9篇 |
2012年 | 6篇 |
2011年 | 5篇 |
2010年 | 15篇 |
2009年 | 12篇 |
2008年 | 10篇 |
2007年 | 7篇 |
2006年 | 17篇 |
2003年 | 4篇 |
1998年 | 11篇 |
1997年 | 17篇 |
1996年 | 16篇 |
1995年 | 16篇 |
1994年 | 15篇 |
1993年 | 14篇 |
1992年 | 15篇 |
1991年 | 13篇 |
1990年 | 7篇 |
1989年 | 11篇 |
1988年 | 10篇 |
1987年 | 19篇 |
1986年 | 17篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 13篇 |
1980年 | 10篇 |
1979年 | 13篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1961年 | 4篇 |
1959年 | 6篇 |
1958年 | 9篇 |
1957年 | 8篇 |
1956年 | 7篇 |
1955年 | 3篇 |
1954年 | 4篇 |
1948年 | 6篇 |
1947年 | 4篇 |
1946年 | 3篇 |
1945年 | 4篇 |
1943年 | 4篇 |
1941年 | 4篇 |
1940年 | 6篇 |
排序方式: 共有493条查询结果,搜索用时 15 毫秒
101.
P. GUSTIN A. R. DHEM P. LEKEUX F. LOMBA F.J. LÁNDSÉR K. P. VAN DE WOESTIJNE 《Journal of veterinary pharmacology and therapeutics》1988,11(4):374-380
Gustin, P., Dhem, A.R., Lekeux, P., Lomba, F., Lándsér, F.J. & Van de Woestijne, K.P. Investigation of the effects of histamine inhalation on the tracheobronchial tree of calves by the forced oscillation technique. J. vet. Pharmacol. Therap. 11 , 374–380.
Effects of histamine inhalation were investigated with two different techniques in nine conscious, healthy calves. The oesophageal balloon technique was used to measure the dynamic respiratory compliance (Cdyn ) and the pulmonary resistance (RL). The reactance (Xrs ) and the resistance (Rrs ) of the respiratory system were measured at high frequencies by the forced oscillation technique. These parameters were recorded before and after histamine inhalation. Three histamine dihydrochloride solution concentrations were used (16 mg/ml; 32 mg/ml; 64 mg/ml). Histamine inhalation induced a decrease in Cdyn and Xrs an increase in Rrs , RL and of the resonant frequency and a negative frequency dependence of Rrs . Some of these changes were satisfactorily correlated with the histamine solution concentrations. The resonant frequency was well correlated with Cdvn . It was concluded that histamine inhalation induces a decrease of the calibre of small and large airways and a non-homogeneous behaviour of the pulmonary ventilation in awake calves. The forced oscillation technique can be used to perform an inhalation provocation test in unsedated animals. 相似文献
Effects of histamine inhalation were investigated with two different techniques in nine conscious, healthy calves. The oesophageal balloon technique was used to measure the dynamic respiratory compliance (C
102.
Aphid honeydew can reduce fungicide effectiveness against necrotrophic pathogens of wheat under controlled conditions. In 1988 and 1989, field experiments were carried out at different locations in The Netherlands, to assess the interference of honeydew with fungicide effectiveness under field conditions, and to establish whether honeydew consumption by naturally occurring saprophytes could prevent this effect. Different combinations of chemicals were used to create differences in saprophytic population densities and aphid populations, which were expected to result in differences in the amount of honeydew and other nutrients on the leaves. In two of the experiments, Septoria nodorum was the only necrotrophic pathogen present; in the other two the only necrotroph was S. tritici . On several sampling dates, the effect of the fungicides was significantly enhanced by addition of insecticide, most often when the saprophytes were reduced by maneb/anilazine. This effect of insecticide is ascribed to prevention of interference of honeydew with fungicide activity, and not to a direct effect of insecticide, as insecticide alone had no effect on necrosis. On the basis of the fact that interference of honeydew with fungicide activity was most apparent when saprophytic population densities were reduced, it is concluded that the naturally occurring saprophytes can generally prevent the effect of honeydew. The same interactions are likely to occur between other nutrients and fungicides, and it is therefore argued that the naturally occurring saprophytes should be protected by elimination of harmful chemicals. 相似文献
103.
The effect of nutrients on reduction of the germination and mycelial growth of Septoria nodorum by the fungicides propiconazole, fenpropimorph and prochloraz, and on the reduction of S. nodorum infection by prochloraz, was tested on wheat plants in a controlled environment. The nutrients tested were aphid honeydew, sucrose, a mixture of amino acids and combinations of sucrose with yeast extract and amino acids, all in different concentrations. All nutrients could stimulate S. nodorum infection in combination with the tested prochloraz concentrations (4.5–45 mg a.i./1), but amino acids did not significantly stimulate infection in the fungicide-free treatments. The stimulating effect of the nutrients was generally stronger with higher nutrient/fungicide ratios. Aphid honeydew had more effect than its main components sucrose and amino acids separately. Antagonism between nutrients and prochloraz was determined with the Colby method and from dose-response curves by comparing ED50 S and drawing antagonism isoboles. Aphid honeydew, sucrose and amino acids caused an up to 10-fold increase of the ED50 and can be considered antagonistic to prochloraz. 相似文献
104.
To assess the potential contribution of growing highly competitive crops to control Cyperus esculentus in the Netherlands, the influence of silage maize, hemp, winter barley and silage winter rye on emergence, growth and reproduction of this weed was studied in two field experiments. Growth and reproduction of C. esculentus (determined both as tuber production per plant and density of the weed in the subseuent crop maize) was reduced by each crop, compared to plots in which no crop was grown. In hemp, hardly any tuber production was observed. By growing a green manure crop after harvest of the winter barley the tuber production of the weed was reduced to about 40% of that in winter barley followed by fallow. Decreasing the light regime in a greenhouse experiment in the same order as was observed in the crops winter barley, maize and hemp, caused a similar reduction of tuber production to that found in the field. Therefore, it is suggested that competition for light is the main factor explaining the observed crop effects on the population dynamics of the weed. It is concluded that growing competitive crops as hemp in rotation may effectively complement chemical control of C. esculentus. 相似文献
105.
P. Kastelein W. G. van Slobbe G. T. N. De Leeuw 《European journal of plant pathology / European Foundation for Plant Pathology》1990,96(2):113-117
Fatal yellowing in oil palms from Brazil and Ecuador is characterized by a chlorosis of the young unfolded leaves and a decay of spear leaves. Contrary to healthy-looking palms, diseased palms do not have roots with soft and white tips.In search for a possible causal agent of fatal yellowing, tissues of leaves, the apical region of stems and root tips of healthy-looking and diseased palms were examined by light microscopy. Fungi and bacteria were frequently, but not always found in necrotic lesions in the leaves. These organisms, however, have never been found outside the lesions or in the vascular tissues of affected palms, nor in the tissues of healthy-looking palms. Tyloses frequently occluded the xylem vessels of affected leaves. In a diseased palm from Ecuador hypertrophic cells were found in the epidermal layer of the pinnae of a spear leaf with water-soaked lesions. In the apical region of the stems and roots of diseased palms, only a few meristematic cells could be detected.Samenvatting Speerrot van oliepalmen in Brazilië en Ecuador wordt gekenmerkt door vergeling van de jongere, geheel geopende bladeren en een rot van de speer. In tegenstelling tot palmen zonder ziekteverschijnselen, hebben aangetaste palmen geen wortels met zachte, witte worteltoppen.Weefsel van bladeren, de apex van de stam en toppen van jonge wortels van gezonduitziende en zieke palmen werden m.b.v. de lichtmicroscoop onderzocht op de aanwezigheid van een eventueel pathogeen. Schimmels en bacteriën werden vaak, doch niet altijd, waargenomen in necrotische lesies op de bladeren, maar nooit buiten lesies of in de vaatbundels van zieke palmen en de weefsels van gezond-uitziende palmen. Vaak verstopten thyllen de houtvaten van aangetaste bladeren. In een speerblad van een zieke palm uit Ecuador werden enige gehypertrofieerde cellen waargenomen in de epidermis van pinnae met waterige lesies. In de top van de stammen en wortels werden slechts enkele meristematische cellen waargenomen. 相似文献
106.
107.
Summary. Photosynthesis, respiration and transpiration of whole platns are continuously recorded with the assembly described. An infra-red gas analyser is used for photosynthesis and respiration measurements, while for transpiration data psychrometers are employed, Air and leaf temperatures as well as light intensity are recorded. The assimilation chamber is constructed in such a way that whole platns of various plant species can be investigated under constant conditions of CO2 content of the air and air humidity. Some experiments with simazine and monuron are described.
Un appareil pour enregistrer continuellement l'échange de CO2 et la transpiration des plantes entiéres 相似文献
Un appareil pour enregistrer continuellement l'échange de CO
108.
Effect of body condition score and reuse of progesterone‐releasing intravaginal devices on conception rate following timed artificial insemination in Nelore cows
下载免费PDF全文
![点击此处可从《Reproduction in domestic animals》网站下载免费的PDF全文](/ch/ext_images/free.gif)
LL Pereira AP Ferreira WG Vale LR Serique KAL Neves AC Morini BM Monteiro AHH Minervino 《Reproduction in domestic animals》2018,53(3):624-628
This study had the aim of investigating the efficiency of timed artificial insemination (TAI) through the progesterone‐releasing intravaginal device (PRID), used in new condition and for the second and third times in Nelore cows. The effects of device reuse and body condition score (BCS) on the conception rate (CR) were evaluated in 1,122 multiparous Nelore cows (mean BCS of 2.7 ± 0.4), which were randomly distributed into three groups that received new (n = 330), once (n = 439) and twice used (n = 353) PRID. Among the 1,122 females that underwent TAI, 573 became pregnant, thus representing an overall CR of 51.06%. Cows with BCS between 2.75 and 4.0 had greater (p < .0001) CR (69.75%) than cows with BSC of 2.0–2.5 (32.98%). It was observed that the CR through using PRID was 60.00%, 51.71% and 41.93% for new, once and twice used PRID, respectively, with difference between all groups (p < .0001). Under tropical conditions, animals with BCS greater than 2.5 had a higher CR, and the CR decreased proportionally with the number of times that the PRID had been used. 相似文献
109.
110.