全文获取类型
收费全文 | 350篇 |
免费 | 21篇 |
专业分类
林业 | 22篇 |
农学 | 20篇 |
基础科学 | 6篇 |
76篇 | |
综合类 | 45篇 |
农作物 | 18篇 |
水产渔业 | 27篇 |
畜牧兽医 | 119篇 |
园艺 | 10篇 |
植物保护 | 28篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 9篇 |
2019年 | 16篇 |
2018年 | 13篇 |
2017年 | 11篇 |
2016年 | 4篇 |
2015年 | 8篇 |
2014年 | 11篇 |
2013年 | 10篇 |
2012年 | 25篇 |
2011年 | 20篇 |
2010年 | 28篇 |
2009年 | 21篇 |
2008年 | 18篇 |
2007年 | 32篇 |
2006年 | 21篇 |
2005年 | 23篇 |
2004年 | 18篇 |
2003年 | 18篇 |
2002年 | 7篇 |
2001年 | 1篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1967年 | 1篇 |
1929年 | 1篇 |
排序方式: 共有371条查询结果,搜索用时 15 毫秒
91.
Meirelles-Bartoli RB Mathias LA Samartino LE 《Tropical animal health and production》2012,44(7):1575-1579
Brucella suis has been recognized as the major etiological agent of human brucellosis in areas free from Brucella melitensis infection. However, with changes in swine management, the occurrence of swine brucellosis has decreased as has the human incidence of B. suis infection. A swine brucellosis outbreak within a herd from Jaboticabal (S?o Paulo, Brazil) was detected in July 2006. The herd comprised approximately 300 sows and 1,500 finishing animals. Many sows within this herd experienced abortions, while others exhibited vaginal discharge; three sows suffered posterior paralysis. Among 271 sows, 254 (93.7%) tested positive for brucellosis by complement fixation, and among 62 randomly bled finishing animals, 17 (27.4%) also tested positive. The B. suis biovar 1 was cultured from 14 aborted fetuses and six sows. Brucella was identified using routine methods. Fourteen farm workers were tested using agglutination tests, with three workers showing evidence of Brucella antibody titers. A 39-year-old woman, who worked with maternal pigs and had direct contact with aborted fetuses, presented an agglutinating titer of 480?IU/mL and displayed clinical signs of infection. Our findings suggest that despite a reduction of swine brucellosis throughout Brazil, B. suis infection still occurs, thereby posing a zoonotic risk. 相似文献
92.
Miguel Alvarez Paul Leparmarai Gereon Heller Mathias Becker 《Arid Land Research and Management》2017,31(1):71-80
Prosopis juliflora is a perennial shrub introduced in the 1980s to the Baringo District in central Kenya, and became highly invasive starting around the late 1990s. This period coincides with a shift of the composition of ruminant herds from formerly cattle to goats in this area. To assess the possible role of this shift in herd structure on P. juliflora spread, we conducted feeding trials and germination tests to determine the capacity of seeds to survive the passage through the intestinal tract of goats and cattle, comparing germination with chemically scarified and untreated seeds. Recovery of seeds eight days after ingestion was lower from goats (7%) than from cattle (15%) dung. Germination dynamics were similar for seeds that had been manually extracted from pods with those recovered after intestinal passage. Chemically scarified seeds germinated fastest and reached a germination rate of 100% within five days. While no apparent scarification effect was observed, the main contribution of endozoochorous dispersal of Prosopis seeds is their release from the enclosing pod segments, their dispersal away from the mother plant and possibly the provision of nutrients by the dung for their establishment and initial growth. 相似文献
93.
Jacqueline L.?FrairEmail author Evelyn?H.?Merrill Darcy R.?Visscher Daniel?Fortin Hawthorne L.?Beyer Juan M.?Morales 《Landscape Ecology》2005,20(3):273-287
Animals may respond to spatial and temporal heterogeneity by altering their movement patterns. The time an animal spends in an area of a given size is termed ȁ8first-passage timeȁ9 and can be used to identify the scales at which different movement processes occur. Using first-passage time and 2-h observations, we identified nested spatial scales representing three movement behaviours for elk (Cervus elaphus) – inactive/resting (moves < 50 m), active/foraging (x̄ = 276.7 m, SD = 56.6), and active/relocating (x̄ = 1628.3 m, SD = 436.6). Our ability to identify inactive behaviour was limited by GPS accuracy. The scale separating relocating and foraging behaviour ranged 550–1650 m across individuals and varied quadratically with the mean patch size of cutover forest in an animal’s home range. We classified path segments into the 3 movement behaviours and related behaviours to local environmental conditions. Elk were likely to be inactive in areas having a low predicted use by wolves (Canis lupus), farther than 50 m from anthropogenic linear clearings, and where microclimatic conditions were cool (high shrub cover and north to east-facing slopes). In contrast, elk were most likely to forage in areas having intermediate levels of herbaceous biomass and low movement costs. Elk were most likely to be relocating when in areas of high wolf use, when close to linear clearings, and in energetically costly situations such as moving upslope. We discuss how elk use of potential foraging habitats may be restricted in this landscape by risks imposed by predators, humans, or both. 相似文献
94.
Evelyn Aigho?Aremu Koichi?Tanaka Yasunori?Akagi Nitaro?Maekawa Hajime?Akamatsu Motoichiro?Kodama Hiroshi?OtaniEmail author 《Journal of General Plant Pathology》2004,70(2):139-142
Fungi inhabiting Japanese pear were isolated from internal tissues of cv. Nijisseiki, and culture filtrates (CFs) of 100 isolates were evaluated for their inhibitory activity against infection by Alternaria alternata Japanese pear pathotype. CFs of 11 isolates inhibited lesion formation on the pear by the pathogen. Among these isolates, CFs of five isolates inhibited spore germination. CFs of the six other isolates inhibited appressorial formation, infection hypha formation, AK-toxin production, or a combination of these actions. Analysis of sequence homology in the rDNA ITS1 regions of these isolates showed that most isolates had high homology with some fungal endophytes. 相似文献
95.
Jérôme Cortet Mathias N. Andersen Bryan Griffiths Bernard Lacroix Jacqueline Thompson 《Soil biology & biochemistry》2006,38(1):195-199
The effects of maize expressing the Bacillus thuringiensis Cry1Ab protein (Bt maize) on decomposition processes under three different European climatic conditions were assessed in the field. Farming practices using Bt maize were compared with conventional farming practices using near-isogenic non-Bt maize lines under realistic agricultural practices. The litter-bag method was used to study litter decomposition and nitrogen mineralization dynamics of wheat straw. After 4 months incubation in the field, decomposition and mineralization were mainly influenced by climatic conditions with no negative effect of the Bt toxin on decomposition processes. 相似文献
96.
Evelyn Aline Arendt Couto Juliana Kath Juliana Aparecida Homiak Heriksen Higashi Puerari 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2016,66(4):346-352
Nematodes have difficult control and complex handling, but considering the physiological and biochemical changes that micronutrients promoting in plants, there is possibility that the supply with these chemicals increases the resistance of plants against nematodes. Thus, the present study aimed to assess the effect of the application of boron and zinc on the reproduction of Meloidogyne incognita, embryonic development and juvenile nematode hatching. Nematode reproduction was evaluated in tomato plant inoculated with 2000 eggs and treated in the aerial part with boron or zinc at the following doses: 0, 1/2, 1×, 2× and 4× the manufacturer's recommendation (100 and 30?g/L, respectively), with the plants assessed 60 days after inoculation. For assessment of embryonic development and juvenile hatching, 1?mL nematode suspension was placed in Petri dishes containing 9?mL of the same doses of boron and zinc, and assessment occurred four and eight days after incubation. Results obtained showed that boron controlled nematode population at the dose of 400?g/L and promoted juvenile hatching when used at maximum dosage on the eighth day. Zinc reduced the number of galls and the number of eggs at the dose of 60?g/L, but did not exhibit direct effect on nematode. 相似文献
97.
Dawid C Henze A Frank O Glabasnia A Rupp M Büning K Orlikowski D Bader M Hofmann T 《Journal of agricultural and food chemistry》2012,60(11):2884-2895
To gain a more comprehensive knowledge on whether, besides the well-known piperine, other compounds are responsible for the pungent and tingling oral impression imparted by black pepper, an ethanol extract prepared from black pepper (Piper nigrum L.) was screened for its key sensory-active nonvolatiles by application of taste dilution analysis (TDA). Purification of the compounds perceived with the highest sensory impact, followed by LC-MS and 1D/2D NMR experiments as well as synthesis, led to the structure determination of 25 key pungent and tingling phytochemicals, among which the eight amides 1-(octadeca-2E,4E,13Z-trienyl)piperidine, 1-(octadeca-2E,4E,13Z-trienyl)pyrrolidine, (2E,4E,13Z)-N-isobutyl-octadeca-2,4,13-trienamide, 1-(octadeca-2E,4E,12Z-trienoyl)-pyrrolidine, 1-(eicosa-2E,4E,15Z-trienyl)piperidine, 1-(eicosa-2E,4E,15Z-trienyl)pyrrolidine, (2E,4E,15Z)-N-isobutyl-eicosa-2,4,15-trienamide, and 1-(eicosa-2E,4E,14Z-trienoyl)-pyrrolidine were not yet reported in literature. Sensory studies by means of a modified half-tongue test revealed recognition thresholds ranging from 3.0 to 1150.2 nmol/cm2 for pungency and from 520.6 to 2162.1 nmol/cm2 for the tingling orosensation depending on their chemical structure. 相似文献
98.
Evaluation of effects of transgenic Bt maize on microarthropods in a European multi-site experiment 总被引:2,自引:5,他引:2
Jrme Cortet Bryan S. Griffiths Marko Bohanec Damjan Demsar Mathias N. Andersen Sandra Caul Andrew N. E. Birch Cline Pernin Elisabeth Tabone Annette de Vaufleury Xin Ke Paul Henning Krogh 《Pedobiologia》2007,51(3):207-ECOGEN
The effects of maize expressing the Bacillus thuringiensis Cry1Ab protein (Bt maize) on soil microarthropods were assessed in the field at four European locations (two in Denmark and two in France) that differ in their climatic conditions or soil properties. Each site was considered as a separate experiment, with separate statistical comparison. Effects of farming practices using Bt maize were compared with conventional farming practices using near-isogenic non-Bt maize and also (at some of the sites) other conventional varieties. Furthermore, at one field site (Foulum, Denmark), the effects of Bt crops were studied in both conventional tillage and reduced tillage contexts. At another field site (Askov, Denmark), Bt maize effects were also compared to the effects of the chemical insecticide dimethoate. Moreover, at three of the field sites (all except Narbons, France), the possibility of a localised Bt effect around the rhizosphere compared to the bulk soil was assessed by sampling within and between maize rows. There were some significant negative effects of Bt maize on microarthropods in soils with a high clay content. Significant differences of the same magnitude also occurred between different conventional varieties of maize, but the effect of dimethoate appeared clearly greater than Bt effects. It is thus debatable if the Bt maize effect is an effect of the Bt toxin or just an effect of the maize variety. Based on the results, it can be concluded that the effect of Bt maize on soil microarthropods was small and within the normal variation expected in conventional agricultural systems. 相似文献
99.
Monika Rinder Victoria Lang Cordula Fuchs Angela Hafner-Marx Karl-Heinz Bogner Antonie Neubauer Mathias Büttner Heinz Rinder 《Journal of veterinary diagnostic investigation》2007,19(3):279-282
The almost simultaneous initial detections of avian influenza A H5N1 viruses in central Europe in February 2006, at a time devoid of migratory bird activity, raised the question of the origin of these viruses. This report presents molecular data from Europe providing evidence for multiple and spatially overlapping H5N1 introductions into Bavaria, Germany. 相似文献
100.
Francisco M Couto Mário J Silva Vivian Lee Emily Dimmer Evelyn Camon Rolf Apweiler Harald Kirsch Dietrich Rebholz-Schuhmann 《Journal of Biomedical Discovery and Collaboration》2006,1(1):19