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101.
微生物对长白鱼鳞云杉木材渗透性的影响 总被引:6,自引:3,他引:6
本文利用水池贮存处理木材研究了细菌对改善长白鱼鳞云杉木材渗透性的有效性。渗透性的测定采用水上升置换气流法。试验结果表明,水池贮存处理长白鱼鳞云杉气干材10周,不仅可以非常显著地增加其边材的渗透性(渗透性平均增加29倍),而且其心材渗透性亦有明显改善(平均渗透性增加1.52倍)。但心材试样渗透性增加不均匀,仅有50%的心材试样在水池贮存处理后渗透性得到了增加。渗透性增加的原因主要是由于边材和部分心材试样受到短芽孢杆菌(Bacillus brevis)等细菌的侵蚀,据电镜观察,边材大多数具缘纹孔的纹孔塞被细菌降解后形成空洞,心材的管胞内壁及具缘纹孔的纹孔缘上有细菌存在。 相似文献
102.
利用纳米SiO_2表面羟基,与不同的硅烷偶联剂以及叔胺反应制得了2种季铵化纳米Si0_2,对产物进行了表征、抑菌性评价,并对产物浸渍改性处理后竹材的疏水性进行研究。结果表明:1)2种合成方法均制得了季铵化纳米Si0_2,Zeta电位为正值,平均粒径QASN-1纳米SiO_2QASN-2。2)抑菌圈试验表明,季铵化纳米SiO2_对竹材8种主要侵害菌有不同程度的抑制作用。3)经过改性的竹块表面由亲水性变为疏水性,且水接触角减小的速度要小于改性前的。由此可见,季铵化纳米Si0_2可用于竹材的侵害菌防护和防水。 相似文献
103.
Aušra Arlauskienė Aleksandras Velykis Alvyra Šlepetienė Dalia Janušauskaitė 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2016,66(8):677-687
ABSTRACTDuring 2008–2011, model field experiments were carried out at the Joni?k?lis Experimental Station of Lithuanian Research Centre for Agriculture and Forestry on a clay loam Endocalcaric Endogleyic Cambisol. The study was aimed to establish the comparison of various postharvest practices (mineral nitrogen fertiliser alone or together with a bioactivator Penergetic k, livestock slurry, red clover biomass and straw incorporation in the soil by a stubble cultivator at a 10 cm depth) on the acceleration of the initial (nine-month period) decomposition of winter wheat straw. During this period, straw mass decomposition intensity was 20.7–29.1%, carbon (C) concentration decreased by 6.5–22.8%, while an increase in nitrogen (N) by 1.1–2.2 times was observed. The highest straw decomposition rate was recorded when after straw incorporation autumn was warm and humid. That year straw mass C to N ratio (C/N) was 38–46. Under less-favourable autumn conditions, the highest decomposition of straw was achieved, having applied mineral N (with and without Penergetic) and livestock slurry and having incorporated the straw in the soil (C/N = 40–55). A slower decomposition rate was observed for the straw spread on the soil surface with mineral N addition or on undersown red clover. 相似文献
104.
105.
Franciska T. de Vries Ellis Hoffland Lijbert Brussaard 《Soil biology & biochemistry》2006,38(8):2092-2103
It is frequently hypothesised that high soil fungal/bacterial ratios are indicative for more sustainable agricultural systems. Increased F/B ratios have been reported in extensively managed grasslands. To determine the shifts in fungal/bacterial biomass ratio as influenced by grassland management and to find relations with nitrogen leaching potential, we sampled a two-year-old field experiment at an organic experimental farm in the eastern part of The Netherlands. The effect of crop (grass and grass-clover), N application rate (0, 40, 80, ) and manure type (no manure, farm yard manure and slurry) on the F/B ratio within three growing seasons was tested, as well as relations with soil and crop characteristics, nitrate leaching and partial N balance. Biomass of fungi and bacteria was calculated after direct counts using epifluorescence microscopy. Fungal and bacterial biomass and the F/B ratio were higher in grass than in grass-clover. The F/B ratio decreased with increasing N application rate and multiple regression analysis revealed a negative relationship with pH. Bacterial activity (measured as incorporation of [3H]thymidine and [14C]leucine into bacterial DNA and proteins) showed the exact opposite: an increase with N application rate and pH. Leaching increased with N application rate and was higher in grass-clover than in grass. Partial N balance was more positive at a higher N application rate and showed an inverse relationship with fungal biomass and F/B ratio. We conclude that the fungal/bacterial biomass ratio quickly responded to changes in management. Grasslands with higher N input showed lower F/B ratios. Grass-clover had a smaller fungal biomass and higher N leaching than grass. In general, a higher fungal biomass indicated a lower nitrogen leaching and a more negative partial N balance (or smaller N surplus), but more observations are needed to confirm the relationship between F/B ratio and sustainability. 相似文献
106.
20%寡聚酸碘水剂对黄瓜灰霉病的药效试验 总被引:1,自引:0,他引:1
20%寡聚酸碘水剂(AS)的有效成分为氨基寡糖素与碘的络合物,采用室内生物活性测定及田间药效试验,以50%乙烯菌核利可湿性粉剂(WP)1 000倍液为对照药剂,评价了20%寡聚酸碘AS对黄瓜灰霉病的防治效果。室内抑菌试验结果表明:20%寡聚酸碘AS 1 000倍液、1 500倍液、2 000倍液的抑菌率分别为97.30%、45.90%、14.00%,均低于50%乙烯菌核利WP 1 000倍液(100.00%)。田间药效试验结果表明:20%寡聚酸碘AS 1 000倍液、1 500倍液的田间防效分别为81.66%、74.80%,均高于50%乙烯菌核利WP 1 000倍液(73.87%)。 相似文献
107.
Azawi OI 《Veterinary research communications》2009,33(1):77-85
The aims of this study were to study the prevalence of oviduct abnormalities of buffaloes, investigate bacteria accompanying
hydrosalpinx, pyosalpinx and salpingitis. In addition, the study was designed to investigate the correlation between bacterial
infection of the uterus and oviduct lesions in buffaloes. Bacteriological examinations were performed on hydrosalpinx, pyosalpinx
and salpingitis. Hydrosalpinx was found in 28 (6.9%) cases of which 20 (71.4%) were found unilaterally and 8 (28.6%) bilaterally.
Pyosalpinx was recorded in 12 (2.9%). Three cases (0.7%) of oviducts filled with blood were recorded. Obstruction of oviducts
was recorded in 5 (1.2%). Adhesions between mesosalpinx and perisalpingeal tissues were observed in 7 (1.7) cases. One case
of double oviduct was found in the left side of the tract examined. The most prevalent bacteria recovered from hydrosalpinx
were Corynebacterium hemolyticum and Actinomyces bovis, 42.8% and 28.6%, respectively. No correlation was noticed between bacteria isolated from the uterus and hydrosalpinx. The
most prevalent bacteria recovered from pyosalpinx were Escherichia coli, Archanobacterium pyogenes and Staphylococcus aureus, 33.3%, 26.7% and 16.7%, respectively. Higher rates of leukocyte infiltration (P < 0.01) were observed in the uterine discharge
and pyosalpinx than hydrosalpinx. In a conclusion, the current study disclosed that oviductal lesions seem to be an important
problem in buffalo cows. In addition, there is no correlation between bacteria isolated from uterus and hydrosalpinx. There
is a high correlation between bacteria isolated from uterus and pyosalpinx and salpingitis. The occurrence of pyosalpinx and
salpingitis is mainly due to bacterial infection. Bacterial isolates from pyosalpinx and salpingitis might be related to ascending
infection from the uterus. 相似文献
108.
Our current knowledge on the relevance of microbial diversity and composition for the recovery and maintenance of soil biological processes is rudimentary, partly because experimental substantiation of the importance of community composition to function is scarce. Guided by this gap, we devised a reciprocal transplant experiment to examine the functional behaviour of different microbial communities exposed to two structurally distinct peats. Sterile peat samples representing two types, one humified (sedge) and the other dominated by coarse plant material (fibric), were inoculated with a 10−1, 10−3, 10−5, or 10−8 dilution of either the same or reciprocal peats. After 5 months of incubation, we used a nucleotide-analog technique to label the active bacterial taxa in samples receiving the 10−1 and 10−8 dilutions. We assessed both the peats' functional potential (respiration and nutrient-acquiring and lignin-degrading enzyme activities) and the structures of active and total bacterial communities (PCR-DGGE). In general, we found a decline in respiration rates and increase in enzyme activities with increasing dilution level, but the effect of dilution on bacterial richness was weak. The bacterial community structure and richness depended on both the inoculum source and the peat type. The activity of enzymes involved in nutrient acquisition depended mainly on the soil type, while the lignin-degrading activity was influenced by differences in community composition between peat types. Neither active bacterial populations nor respiration were significantly influenced by peat type or inoculum source. Our results suggest that the relationship between microbial community composition and function is not only related to the taxonomic breadth of the taxa that perform a given function, but may also be shaped by interactions between microorganisms in the inoculum source and the substrate being colonized. 相似文献
109.
110.
Over the past 3 years the frequency of Salmonella hadar infections has increased in Belgium in both poultry and humans. Therefore, the course of infection with S. hadar in poultry was investigated. One day-old and 4 week-old specific pathogen-free chickens were orally infected with one of two S. hadar strains, SH1 or SH2. Mortality was 6% (SH1) and 17% (SH2) in birds infected at 1 day-old. Chickens infected at 1 day-old with SH2 showed a mild diarrhoea. The S. hadar faecal excretion in birds infected at 1 day-old remained high throughout the experiment until 12 weeks post-inoculation (pi). Faecal excretion was lower in older birds. Antibodies to S. hadar were observed from 2 weeks pi (SH2, infected at 1 day-old) or 4 weeks pi (SH1, both groups; SH2, chickens infected at 4 weeks of age). The percentage of chickens with antibodies was higher after infection at 1 day-old than after infection at 4 weeks of age. In a second experiment 1 day-old chicks were infected with SH1 and autopsied at regular intervals until 42 days pi. SH1 was isolated from the caeca from 3 h pi onwards and from the liver and spleen from 18 h until 14 days pi. Serous typhlitis and omphalitis were the main lesions. The number of macrophages in the lamina propria of the caecal tonsils was slightly increased from 18 h until 2 weeks pi. In the liver, inflammation was observed in the portal triads and in the sinusoids. This study indicates that infections with S. hadar lead to intense colonisation of the gut and extensive faecal shedding. It may also cause invasive infections in 1 day-old chickens. 相似文献