全文获取类型
收费全文 | 818篇 |
免费 | 76篇 |
国内免费 | 50篇 |
专业分类
林业 | 22篇 |
农学 | 39篇 |
基础科学 | 2篇 |
108篇 | |
综合类 | 187篇 |
农作物 | 35篇 |
水产渔业 | 105篇 |
畜牧兽医 | 269篇 |
园艺 | 5篇 |
植物保护 | 172篇 |
出版年
2024年 | 10篇 |
2023年 | 20篇 |
2022年 | 28篇 |
2021年 | 24篇 |
2020年 | 34篇 |
2019年 | 63篇 |
2018年 | 29篇 |
2017年 | 40篇 |
2016年 | 51篇 |
2015年 | 51篇 |
2014年 | 55篇 |
2013年 | 51篇 |
2012年 | 64篇 |
2011年 | 48篇 |
2010年 | 33篇 |
2009年 | 37篇 |
2008年 | 46篇 |
2007年 | 43篇 |
2006年 | 30篇 |
2005年 | 28篇 |
2004年 | 18篇 |
2003年 | 13篇 |
2002年 | 10篇 |
2001年 | 11篇 |
2000年 | 20篇 |
1999年 | 16篇 |
1998年 | 13篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 7篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
排序方式: 共有944条查询结果,搜索用时 15 毫秒
71.
72.
本研究通过探索低浓度阿奇霉素对猪链球菌2型蛋白表达、荚膜多糖与药物敏感性的影响,为进一步研究环境中低浓度抗生素对微生物的影响奠定基础。用低浓度阿奇霉素处理猪链球菌2型,利用蛋白质组学iTRAQ技术,筛选关键差异表达蛋白。同时测定猪链球菌2型的荚膜多糖含量和药物敏感性。结果显示,共鉴定到差异表达蛋白174个,占总鉴定蛋白的11.6%,多数差异表达蛋白参与催化和代谢过程,属于膜蛋白,其中,3个荚膜多糖蛋白、9个ABC转运蛋白、1个50 S核糖体蛋白、1个核糖体RNA甲基转移酶、1个DNA回旋酶上调表达;8个荚膜多糖蛋白、4个50S核糖体蛋白、4个30S核糖体蛋白、1个核糖体RNA甲基转移酶、1个DNA聚合酶IV下调表达。用低浓度阿奇霉素处理猪链球菌2型,发现其对多种抗生素的敏感性降低,存活下来的菌株,恢复正常培养后,药物敏感性恢复。用低浓度阿奇霉素处理猪链球菌2型,荚膜多糖含量也未发生大幅度变化。猪链球菌2型通过改变自身蛋白质组的表达量,以适应低浓度阿奇霉素的选择压力。与低浓度阿奇霉素共存时,猪链球菌2型开启外排泵系统,会增加细菌产生多重耐药的风险。 相似文献
73.
Pot experiments were conducted to evaluate the level of imazamox tolerance in five red rice ( Oryza sativa L.) and four barnyardgrass (three Echinochloa crus-galli (L.) Beauv. and one Echinochloa oryzoides (Ard.) Fritch) morphologically distinct biotypes collected from rice fields in northern Greece. The susceptibility of barnyardgrass biotypes to propanil was also studied. Red rice biotypes were not controlled by imazamox applied at 40 g ha−1 . In contrast, 80 g imazamox ha−1 provided 56–84% red rice control (averaged across shoot number and fresh weight reduction). Not all barnyardgrass biotypes were susceptible to imazamox applied postemergence. However, propanil applied at 2.6 kg ha −1 controlled the E. crus-galli biotypes well, but propanil applied at rates of 2.6 and 5.2 kg ha −1 was not effective in reducing the shoot number and fresh weight of the E. oryzoides biotype. Propanil applied at 10.4 kg ha −1 reduced the shoot number and fresh weight of this biotype by 78 and 85%, respectively. In most cases, a linear equation ( y = % of control, x = g ha−1 ) provided the best fit for regressions between red rice or barnyardgrass shoot number or fresh weight and imazamox rates. The results of this study suggest that postemergence application of imazamox is not effective against all red rice and barnyardgrass biotypes found in the rice fields of Greece and that significant variability regarding herbicide efficacy among biotypes might exist. 相似文献
74.
3种生物源杀虫剂对杜仲梦尼夜蛾的毒力及防效 总被引:1,自引:0,他引:1
针对专性为害杜仲的食叶害虫杜仲梦尼夜蛾(Orthosia songi Chen et Zhang)幼虫进行室内毒力测定,比较了3种生物源杀虫剂对其3龄和5龄幼虫的杀虫活性,并进行了林间药效测定和防治示范试验。结果显示:甲氨基阿维菌素苯甲酸盐(甲维盐)对3龄和5龄幼虫的LC50值分别为0.152 5和0.204 7μg/L,苦参碱的LC50值分别为65.306 0和124.735 8μg/L,印楝素的LC50值分别为165.871 7和257.749 0μg/L。林间药效测定结果显示5.7%甲维盐微乳剂300万倍液防治效果最好,7d后校正死亡率达91.34%。防治示范试验表明,5.7%甲维盐微乳剂75 000倍液防治效果达95.69%,显著高于0.3%苦参碱水剂750倍液的防治效果(80.28%),且药剂成本7.5元/hm2,仅为后者的1.9%。 相似文献
75.
76.
77.
78.
Pasquale Borrelli Panos Panagos Cristiano Ballabio Emanuale Lugato Melanie Weynants Luca Montanarella 《Land Degradation \u0026amp; Development》2016,27(4):1093-1105
Understanding spatial and temporal patterns in land susceptibility to wind erosion is essential to design effective management strategies to control land degradation. The knowledge about the land surface susceptible to wind erosion in European contexts shows significant gaps. The lack of researches, particularly at the landscape to regional scales, prevents national and European institutions from taking actions aimed at an effective mitigating of land degradation. This study provides a preliminary pan‐European assessment that delineates the spatial patterns of land susceptibility to wind erosion and lays the groundwork for future modelling activities. An Index of Land Susceptibility to Wind Erosion (ILSWE) was created by combining spatiotemporal variations of the most influential wind erosion factors (i.e. climatic erosivity, soil erodibility, vegetation cover and landscape roughness). The sensitivity of each input factor was ranked according to fuzzy logic techniques. State‐of‐the‐art findings within the literature on soil erodibility and land susceptibility were used to evaluate the outcomes of the proposed modelling activity. Results show that the approach is suitable for integrating wind erosion information and environmental factors. Within the 34 European countries under investigation, moderate and high levels of land susceptibility to wind erosion were predicted, ranging from 25·8 to 13·0 M ha, respectively (corresponding to 5·3 and 2·9% of total area). New insights into the geography of wind erosion susceptibility in Europe were obtained and provide a solid basis for further investigations into the spatial variability and susceptibility of land to wind erosion across Europe. © 2014 The Authors. Land Degradation and Development published by John Wiley & Sons, Ltd. 相似文献
79.
Summary The possibility of using proline accumulation and fluorescence inhibition as predictive tests for drought tolerance in durum wheat has been investigated. The drought susceptibility of 25 genotypes was evaluated by comparing yields and yield components in irrigated and non irrigated conditions in the field. A drought susceptibility index (DSI) was calculated based on yields from irrigated and dry treatments and compared with the results obtained using the two physiological criteria. Proline accumulation and chlorophyll fluorescence inhibition were found to be significantly and negatively correlated with DSI of grain yield, biological yield, and thousand kernel weight, and tiller index. The use of both criteria for breeding durum wheat in Mediterranean dryland is discussed. 相似文献
80.
M.?K.?Dhillon H.?C.?SharmaEmail author B.?V.?S.?Reddy Ram?Singh J.?S.?Naresh Zhu?Kai 《Euphytica》2005,144(3):275-283
Summary The shoot fly, Atherigona soccata is an important pest of sorghum, and host plant resistance is one of the most effective components for managing this pest.
Most of the hybrids grown in India based on milo cytoplasm (A1 cytoplasm) are highly susceptible to shoot fly. Therefore, the present studies were undertaken to evaluate different male-sterile
cytoplasms (CMS) for their relative susceptibility to sorghum shoot fly. Oviposition and deadheart formation were significantly
lower on the maintainer lines as compared to the corresponding male-sterile lines. Among the cytoplasms tested, A4M cytoplasm showed antixenosis for oviposition and suffered lower deadheart formation than the other cytoplasms tested. The
A4G1 and A4M cytoplasms suffered lower deadhearts in tillers than the other cytoplasms. Recovery following shoot fly damage in A4M, A3, and A2 cytoplasms was better than in the other cytoplasms tested. The larval and pupal periods were longer and male and female pupal
weights lower in A4M and A4VzM CMS backgrounds compared to the other CMS systems. Fecundity and antibiosis indices on CMS lines were lower than on the
B-lines. The A4M cytoplasm was found to be relatively resistant to sorghum shoot fly, and can be exploited for developing shoot fly-resistant
hybrids for sustainable crop production in future. 相似文献