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排序方式: 共有1984条查询结果,搜索用时 15 毫秒
1.
[目的]建立快速、简便、高灵敏度的检测硝基苯类化合物的方法。[方法]建立单液滴微萃取-毛细管气相色谱法(SDME-GC)测定水样中的硝基苯类化合物。以外标法测定了硝基苯、2-硝基甲苯、3-硝基甲苯、4-硝基甲苯、3-硝基氯苯的标准工作曲线方程、检出限、线性范围,并在相同实验条件下测定了实际工业废水样中上述硝基苯类化合物的含量、加标回收率范围及相对标准偏差范围。[结果]5种硝基苯类化合物检出限很低,最小能达到8.9×10-4μg/ml,且均在较宽的线性范围内表现出良好的线性关系(相关系数均在0.99以上)。该方法的回收率、相对标准偏差符合要求。[结论]单液滴微萃取一毛细管气相色谱法预处理快捷、环保、价廉且富集效果好,操作简便、快速、准确、灵敏度高、线性范围较宽。 相似文献
2.
Hayley C. Norman Matt G. Wilmot Dean T. Thomas David G. Masters Dean K. Revell 《Livestock Science》2009,121(2-3):162-172
The stable carbon isotope technique has been widely used to infer the dietary ecology of a range of animal species; however calibration of the technique with animals fed known diets is essential for accurate back-calculation of dietary preferences. The aim of this study was to identify suitable samples and back-calculation methods to predict short-term (2 to 3 week) dietary selection by sheep among plants with C3 and C4 photosynthetic pathways. Variation in integration time of dietary carbon into plasma and faeces; diet-tissue discrimination of carbon isotopes (fractionation) and the importance of accounting for the digestible or indigestible components of the diet was investigated. The results indicate that faecal and rumen samples provided the most accurate prediction of short term dietary changes in sheep selecting between C3 and C4 plants. The most accurate back-calculation method for these samples used δ13C of the C3 and C4 plants and accounted for both diet-tissue discrimination and differences in the indigestibility between the C3 and C4 forage. For faecal samples, the organic matter content of the diet originating from C4 plants could be predicted with a mean error as low as 2.7%. Wool and plasma samples were not conducive to predicting proportion of C4 forage in the diet within 18 days after a change in diet; however plasma could be used to discriminate between animals fed 100% C3 and C4 diets after 3 days. The δ13C technique provides a valuable tool for researchers when designing pastures for dual environmental and production purposes. An understanding of what sheep select allows for development of appropriate grazing management strategies to optimise productivity and/or persistence of target species. 相似文献
3.
以德系、法系安哥拉、沪2071 系和GSAB兔为育种素材,通过合成杂交方式建立选育基础群,实施半开放式核心群世代选育,经过5 个世代育成粗毛型兔新品系。新品系平均年产毛量1704g,兔毛品质优良,粗毛率20.11% ,料毛比40.33∶1,成年体重5.5kg,体长55cm ,胸围40cm ,平均窝产仔7.36只,育成成活率92% 。适应性和抗病力较强,体质健壮,外貌整齐,遗传性稳定 相似文献
4.
研究不同检测方法反应出的容器污染情况,采用发酵法、滤膜法以及涮洗法对乳品塑料预制瓶容器在不同贮存时间和不同污染程度所产生微生物进行检测.结果表明:发酵法不能全面反应出容器的污染情况,涮洗法和滤膜法的采样方式更全面,能更好地反应污染情况.但滤膜法不适用于高污染的环境下的检测.因此,涮洗法更适合在工业化生产中用于批量检测. 相似文献
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An experiment was conducted to scientifically identify the appropriate feed for Gansu Alpine Fine Wool ewes in order to change the animals' breeding mode, which currently can only be mated at the age of 2.5 years due to insufficient nutritional supply. The experiment selected 48 12-month-old ewes and randomly divided them into group a (Diet 1), group b (Diet 2), group c (Diet 3), and a control group with no supplementary feeding. The feed test was run for 90 days. The rumen pH of groups a and b were very significantly higher (P<0.01) or group c significantly lower (P<0.05) than control group. The rumen ammonia nitrogen, protein nitrogen and total nitrogen of groups a, b and c were all higher than control group (P<0.01). The total volatile fatty acids of group a and b were all higher than the control group (P<0.01), group b significantly higher than group c (P<0.05). The molar ratio of acetic acid and propionic acid in group a was very significantly higher than control group (P<0.01), group b and c were significantly higher than control group (P<0.05). The molar ratio of butyric acid in group a was very significantly higher than group c (P<0.01). The ratio of acetic acid and propionic acid in group b was significantly lower than control group (P<0.05). The number of several rumen fiber-degrading bacteria and protozoa in groups a, b and c were very significantly (P<0.01) or significantly (P<0.05) higher than the control. In conclusion, this study shows that supplementary feeding can positively affect the rumen metabolic parameters and the number of several rumen microorganisms in Gansu Alpine Fine Wool ewes. In general, the effects of Diet 1 were the strongest, while Diet 2 also produced notable improvements. © 2018, Editorial Office of Acta Prataculturae Sinica. All rights reserved. 相似文献
8.
通过对青海天峻县高原型藏羊毛纤维物理性能分析。结果表明纤维类型重量百分比:无髓毛、有髓毛和干死毛含量:周岁羊平均分别占48.87%,43.23%,15.38%,无干死毛羊只占15.11%;成年羊平均分别占40.85%,44.40%,17.52%,无干死毛羊只占14.41%。羊毛纤维细度:无髓毛、有髓毛和干死毛细度,周岁羊平均分别为21.06μm,38.85μm,68.31μm,成年羊平均分别为22.44μm,38.67μm,79.29μm。毛辫长、底绒长、毛纤维手排平均长度:周岁羊平均分别为274.13mm,82.72mm,70.05mm;成年羊平均分别为275.30mm,90.70mm,73.21mm。净毛率和色度(Wht、YT):周岁羊平均分别为72.37%,68.68,30.60;成年羊平均分别为73.55%,69.11,30.16。天峻县高原型藏羊具有良好的毛辫长度和底绒长度,而且底绒细度细,粗毛、绒毛比例适中,干死毛含量少,净毛率高,色度好的特点,是纺织地毯、长毛绒和提花毯的优质原料。 相似文献
9.
Objective To estimate the changes in productivity and profitability in a group of wool-growing farms as they adopted major recommendations from agricultural and veterinary studies.
Farms Four wool-growing farms in south western Victoria were selected from the clients of the Mackinnon Project, a farm consultancy service run from the University of Melbourne. Each farm had closely followed recommended procedures, kept comprehensive financial and physical records and had been clients for at least 5 years. The comparison group was the South Western Victoria Monitor Farm Project (SWVMFP), about 45 farms in the same region as the study farms that were monitored annually by Agriculture Victoria.
Procedure For a 7-year period, the financial and physical performance of both groups of farms was estimated. Stocking rate, wool production, gross farm income, farm operating costs, net farm income and return on assets were compared.
Results Mean gross farm income of the four study farms steadily rose from 86% of the average SWVMFP farm before the adoption of recommendations to an average of 155%. During the same period, net farm income rose from 70% to 207% of the average of the SWVMFP. Return on asset of the four farms rose irregularly from 26% to 145% of the average of the SWVMFP. Farm operating costs on the four farms were higher than for the SWVMFP group, but the ratio of costs remained relatively constant.
Conclusion The adoption of proven research results was associated with large increases in net farm income. An increase in gross income, rather than a reduction in costs was the main reason for this. Research results offer a way to increase the financial viability of wool-growing farmers, many of whom are currently unable to maintain their lifestyle, resources and infrastructure. 相似文献
Farms Four wool-growing farms in south western Victoria were selected from the clients of the Mackinnon Project, a farm consultancy service run from the University of Melbourne. Each farm had closely followed recommended procedures, kept comprehensive financial and physical records and had been clients for at least 5 years. The comparison group was the South Western Victoria Monitor Farm Project (SWVMFP), about 45 farms in the same region as the study farms that were monitored annually by Agriculture Victoria.
Procedure For a 7-year period, the financial and physical performance of both groups of farms was estimated. Stocking rate, wool production, gross farm income, farm operating costs, net farm income and return on assets were compared.
Results Mean gross farm income of the four study farms steadily rose from 86% of the average SWVMFP farm before the adoption of recommendations to an average of 155%. During the same period, net farm income rose from 70% to 207% of the average of the SWVMFP. Return on asset of the four farms rose irregularly from 26% to 145% of the average of the SWVMFP. Farm operating costs on the four farms were higher than for the SWVMFP group, but the ratio of costs remained relatively constant.
Conclusion The adoption of proven research results was associated with large increases in net farm income. An increase in gross income, rather than a reduction in costs was the main reason for this. Research results offer a way to increase the financial viability of wool-growing farmers, many of whom are currently unable to maintain their lifestyle, resources and infrastructure. 相似文献
10.
匍匐翦股颖草坪根系对城市生活污水的净化效应 总被引:3,自引:1,他引:3
针对匍匐翦股颖草坪根系对生活污水的净化效应进行了初步的探索,结果表明,城市生活污水能显著促进匍匐翦股颖地上部分叶片的生长,其叶片生长量随着其处理的进程而逐渐增加,至第6周时叶片生长量比净水灌溉的对照增加了75.6%;根系生长在污水灌溉与净水灌溉之间未显示出明显的差异;匍匐翦股颖草坪根系对生活污水中总氮(TN)、总磷(TP)、化学耗氧量(CODCr)的去除率分别达到了71.0%、53.1%、82.8%,而无草坪的裸土对TN、TP、CODCr的去除率只有24.6%、13.0%、44.2%.结果显示了匍匐翦股颖草坪根系对生活污水有着较好的净化效果,有望在城市生活污水处理中应用. 相似文献