全文获取类型
收费全文 | 513篇 |
免费 | 34篇 |
专业分类
林业 | 70篇 |
农学 | 15篇 |
109篇 | |
综合类 | 22篇 |
农作物 | 42篇 |
水产渔业 | 29篇 |
畜牧兽医 | 184篇 |
园艺 | 21篇 |
植物保护 | 55篇 |
出版年
2023年 | 3篇 |
2021年 | 4篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 38篇 |
2017年 | 23篇 |
2016年 | 33篇 |
2015年 | 16篇 |
2014年 | 27篇 |
2013年 | 24篇 |
2012年 | 44篇 |
2011年 | 52篇 |
2010年 | 19篇 |
2009年 | 15篇 |
2008年 | 27篇 |
2007年 | 29篇 |
2006年 | 29篇 |
2005年 | 26篇 |
2004年 | 14篇 |
2003年 | 18篇 |
2002年 | 15篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 7篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1993年 | 3篇 |
1987年 | 2篇 |
1985年 | 3篇 |
1980年 | 2篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1965年 | 2篇 |
1963年 | 2篇 |
1958年 | 1篇 |
1957年 | 1篇 |
1956年 | 1篇 |
1932年 | 1篇 |
1926年 | 2篇 |
1918年 | 2篇 |
排序方式: 共有547条查询结果,搜索用时 24 毫秒
1.
SUMMARY: The activity of enzyme aldolase (ALD) was determined in the sera of Simmental young bulls, with the purpose to see whether there exists a relationship between the enzyme activity and fattening capacity and whether the ALD could be an indicator of the muscle quantity and protein content. Early ALD activity was correlated with slaughter weight and ADG in the last fattening month. The regression analysis suggests that young bulls with higher serum ALD acitivity at the start of the experiment had more total muscles and less bone in the analysed rib part. On the basis of ALD activity in the first fattening month it was possible to estimate protein and fat content in the MLD. ZUSAMMENFASSUNG: Fructose-1,6-biphosphat Aldolase beim Serum Simmentaler Jungbullen. Beziehung zwischen Mastf?higkeit, Muskelmenge und Proteingehalt Aldolase (ALD) Enzymt?tigkeit im Serum von Simmentaler Jungbullen wurden in Hinblick auf eine Beziehung mit Mastf?higkeit, Muskelmenge und Proteingehalt untersucht. Es zeigt sich eine Korrelation zwischen früher ALD Aktivit?t und Schlachtgewicht und Tageszuwachs im Endmastmonat. Regressionsanalyse ergab, da? Jungbullen mit h?herer ALD Aktivit?t bei Mastbeginn mehr Muskelanteil im m. longissimus dorsi und weniger Knochen besitzen. ALD Aktivit?t im ersten Mastmonat erlaubt Sch?tzung des Protein- und Fettgehalts im m. long, dorsi. RESUMEN: Fructosa 1,6-bifosfato aldolasa en el suero de los terneros simentales. Relatión con sus capacidades de ser cebados, su cantidad de músculos y el contenido de proteínas Con el fin de establecer la relación entre la actividad de enzimas y las capacidades durante el proceso de la ceba, asf como para precisar si el ALD puede servir como indicador de la cantidad de músculos y el contenido de proteinas, intentaba determinarse la actividad de los enzimas de aldolasa (ALD) en el suero de los terneros simentales. A base de la actividad indicial del ALD, es posible estimar el peso final de matadero y la crecencia diaria media durante el último mes de la ceba. Tras una análisis regresiva se ha probado que los terneros con una actividad mayor del ALD en el suero a principios del proceso de su ceba tienen más músculos en total en la parte de costillas y m. longissimus dorsi mientras que tienen menos huesos. A base de la actividad del ALD durante el primer mes de la ceba es posible estimar el contenido de proteinas y grasa en m. long, dorsi. RéSUMé: Fructose 1.6-biphosphate aldolase dans le sérum des taurillons de Simmental. Le rapport entre l'aptitude à l'angraissement, la proportion des muscles et la teneur en protéines On a déterminé l'activité de l'enzyme aldolase (ALD) dans le sérum des taurillons de Simmental afin de vérifier s'il existait un rapport entre l'activité des enzymes et l'aptitude à l'engraissement et si l'ALD pouvait être indicatrice de la proportion de muscles et de la teneur en protéines. A la base de l'activité initiale de l'ALD, il est possible d'évaluer le poids de la carcasse et le gain quotidien moyen au cours du dernier mois d'engrais. Par analyse régressive, il a été établi que les taurillons à l'activité supérieure de l'ALD dans le sérum avaient au début de l'engrais plus de muscles au total dans la région costale et le m. longissimus dorsi et moins d'os. A la base de l'activité de l'ALD au cours du premier mois d'engrais il est possible d'évaluer la teneur en protéines et en graisse dans le muscle longissimus dorsi. 相似文献
2.
Concepts and Direction of Induced Systemic Resistance in Plants and its Application 总被引:11,自引:0,他引:11
Joseph Kuć 《European journal of plant pathology / European Foundation for Plant Pathology》2001,107(1):7-12
Resistance to plant disease is often specific and metabolites and receptors contributing to this specificity may have specific structures. However, simple, structurally-unrelated compounds induce systemic resistance in unrelated plants to diverse pathogens including fungi, bacteria and viruses. Both resistance and induced systemic resistance (ISR) are associated with the rapid accumulation of the same structurally unrelated putative defense compounds that have diverse functions. It has been suggested that cultivar (race)-specific resistance is initiated by the specific interaction of a pathogen product (or pathogen induced product) and a plant receptor. However, restricted infection by pathogens can result in ISR and many different compounds can cause ISR. It is thus evident that there are both specific and non-specific routes to the master switch for ISR and there may be more than one master switch. Are reactive oxygen species and free radicals regulating the master switch(es) via both routes? It is also evident there are many switches, other than the master switch. Adding to the complexity of resistance and ISR are the observations that different compounds and pathways may mediate different biochemical resistances. Activation of one of the pathways may antagonize or enhance the activation or effectiveness of another. The review will address these complexities and questions and propose directions of research which require high priority. Factors which encourage and suppress the application of ISR in agriculture will also be addressed. 相似文献
3.
Surprisingly few commercial ELISAs are available for the detection of Toxoplasma gondii infection in animals, and none for use in sheep have been evaluated. We thus compared the Bommeli Diagnostics ELISA Toxotest for the detection of T. gondii antibodies in ruminants with the reference modified agglutination test (MAT) in a series of 180 sheep sera. ELISA results were analysed at two cut-off levels (30%, comprising both weakly positive and positive results, and 100%, comprising only positive results), and compared with MAT at three cut-off levels (titre of 1 : 25, 1 : 50 and 1 : 100). The results showed a moderate agreement of ELISA at both cut-offs (kappa = 0.46 and 0.51) with MAT at a cut-off titre of 1 : 100. However, the specificity and positive predictive value were above 95% only at an ELISA cut-off of 100%, indicating its potential as a diagnostic test, particularly in areas with a high prevalence of infection. On the other hand, lower sensitivity and negative predictive value limit its value as a screening test. Thus, the ELISA Toxotest may be used for quick diagnosis of T. gondii infection in sheep in the field, i.e. for the differential diagnosis of ovine abortion storms. 相似文献
4.
5.
Slađana Č. Alagić Snežana B. Tošić Mile D. Dimitrijević Jelena V. Petrović Dragana V. Medić 《Communications in Soil Science and Plant Analysis》2016,47(17):2034-2045
Inductively coupled plasma optical emission spectroscopy, in combination with calculation of various biological factors, was used in this study not only for a simple illustration of the present status of some essential and non-essential metals such as copper (Cu), zinc (Zn), nickel (Ni), lead (Pb), arsenic (As), and cadmium (Cd) in the grapevine cultivar Rkatsiteli and wild blackberry from East Serbia but also for the estimation of plant bioaccumulation potentials. Great majority of detected metal concentrations were in normal ranges except in few cases: Zn concentrations were at the level of deficiency in almost all plant parts, and some Cu and As concentrations were at the levels that could be considered phytotoxic. Biological accumulation factors provided very informative data on metal accumulation and translocation in both plants and pointed to low accumulation rates of metals except in the case of Cu, Zn, and As in some wild blackberry tissues. 相似文献
6.
Curcumin, a plant-derived polyphenolic compound, naturally present in turmeric (Curcuma longa), has been the subject of intensive investigations on account of its various activities. The implementation of safe, beneficial and highly functional compounds from natural sources in human nutrition/prevention/therapy requires some modifications in order to achieve their multi-functionality, improve their bioavailability and delivery strategies, with the main aim to enhance their effectiveness. The low aqueous solubility of curcumin, its rapid metabolism and elimination from the body, and consequently, poor bioavailability, constitute major obstacles to its application. The main objectives of this review are related to reported strategies to overcome these limitations and, thereby, improve the solubility, stability and bioavailability of curcumin. The effectiveness of curcumin could be greatly improved by using nanoparticle-based carriers. The significance of the quality of a substance delivery system is reflected in the fact that carrying curcumin as a food additive/nutrition also means carrying the active biological product/drug. This review summarizes the state of the art, and highlights some examples and the most significant advances in the field of curcumin research. 相似文献
7.
Filip Franeta Sanja Mikić Željko Milovac Bojan Mitrović Dušanka Inđić Slavica Vuković 《国际虫害防治杂志》2019,65(1):23-32
Maize is arguably the most widely grown crop in the world, but it is often associated with one of its major insect pests, the European corn borer (ECB). The damage caused by this species to maize production is generally variable, but in many cases it is economically significant. This review paper provides an overview of the research findings on the natural plant defence mechanisms against ECB larvae published till now. What is resistance and how it is achieved, what is the chemical response of maize plants to insect feeding and how tolerance can be increased. A short introduction in breeding for resistance and a discussion if the mentioned traits can be used in conventional breeding in order to create maize hybrids less affected by ECB are given. 相似文献
8.
Tančić Živanov Sonja Dedić Boško Dimitrijević Aleksandra Dušanić Nenad Jocić Siniša Miklič Vladimir Kovačević Branislav Miladinović Dragana 《植物病害和植物保护杂志》2019,126(6):565-573
Journal of Plant Diseases and Protection - The study assessed the genetic variability among Macrophomina phaseolina (Tassi) Goid. isolates originating from six different countries (Turkey,... 相似文献
9.
Kladar Nebojša Anačkov Goran Srđenović Branislava Gavarić Neda Hitl Maja Salaj Nebojša Jeremić Katarina Babović Siniša Božin Biljana 《Plant foods for human nutrition (Dordrecht, Netherlands)》2020,75(3):390-395
Plant Foods for Human Nutrition - St. John’s wort has been used for centuries in traditional medicine of many cultures, and nowadays it is well-known as a clinically important antidepressant... 相似文献
10.
Zoran Marković Marko Stanković Božidar Rašković Zorka Dulić Ivana Živić Vesna Poleksić 《Aquaculture International》2016,24(6):1699-1723
The semi-intensive system of carp farming is dominant in inland aquaculture. Although it appears to be simple, this system has a whole range of options, from those based on traditional rearing methods with use of plants from the region where the fish are reared to production based on the use of high-quality concentrated feeds. In this paper, we conduct a comparative analysis of the effect of using cereal grains as opposed to compound feed (pelleted and extruded) on the quantity of fish produced, flesh quality, histological changes in the digestive tract, water quality, and structure of the biocoenosis in the pond ecosystem. When the fish are fed cereal grains, production ranges from 500 to 1500 kg/ha, while using compound feed gives production that is twice as great. The proportions of protein and water are higher and that of lipids lower in flesh of common carp reared on compound feed in relation to fish fed cereal grains. Use of extruded feed gives better content of n-3 polyunsaturated fatty acids and a better n-3/n-6 ratio than when pelleted feed and cereal grains are used. Comparison of water quality in carp ponds under conditions of using various types of feed indicates that there are no significant differences. Although it was expected that feed with a higher percentage of proteins would cause disturbances in the aquatic ecosystem, their continual incorporation into the cycling of matter in the water contributes to maintenance of ecological equilibrium and even indirectly promotes growth of the common carp. 相似文献