全文获取类型
收费全文 | 218篇 |
免费 | 15篇 |
国内免费 | 11篇 |
专业分类
林业 | 29篇 |
农学 | 25篇 |
基础科学 | 3篇 |
15篇 | |
综合类 | 72篇 |
农作物 | 18篇 |
水产渔业 | 15篇 |
畜牧兽医 | 15篇 |
园艺 | 1篇 |
植物保护 | 51篇 |
出版年
2023年 | 4篇 |
2022年 | 2篇 |
2021年 | 8篇 |
2020年 | 9篇 |
2019年 | 3篇 |
2018年 | 9篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2015年 | 3篇 |
2014年 | 12篇 |
2013年 | 10篇 |
2012年 | 20篇 |
2011年 | 10篇 |
2010年 | 17篇 |
2009年 | 14篇 |
2008年 | 8篇 |
2007年 | 16篇 |
2006年 | 11篇 |
2005年 | 11篇 |
2004年 | 4篇 |
2003年 | 10篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有244条查询结果,搜索用时 31 毫秒
1.
养分从牛粪到农田的循环利用是养牛场可持续发展、资源利用和环境保护的重点研究内容。利用奶牛场废水种植水生植物被认为是一种有效的废水处理及养分循环的方法。本文研究了3种浮萍[少根紫萍0128(Landoltia punctata 0128)、膨胀浮萍7589(Lemna gibba 7589)和小浮萍9517(Lemna minuta 9517)]在厌氧发酵过的奶牛场废水中种植时的养分吸收和生物质变化。在28 d的测试期间,种植在稀释比例为1:18的厌氧发酵过的牛奶场废水中的少根紫萍01283获得最高的总氮吸收率(11.6%±1.6%),种植在稀释比例为1:27厌氧发酵过的牛奶场废水中的少根紫萍0128获得最高的总磷吸收率(15.4%±4.4%);相应地少根紫萍鲜重的增长率分别为0.11 g·d-1和0.17 g·d-1。3种浮萍中,少根紫萍最具有吸收牛奶场废水氮、磷并获得较高生物质的潜力。 相似文献
2.
花吊丝竹ISSR反应体系的建立与优化 总被引:1,自引:0,他引:1
建立关于花吊丝竹的ISSR-PCR反应体系,为花吊丝竹种质资源鉴定提供理论基础。采用单因素试验法,对影响PCR扩增效果的Mg~(2+)浓度、d NTPs浓度、Taq DNA聚合酶用量、引物浓度及模板DNA用量等5个PCR反应体系主要成分以及退火温度和循环次数进行分析,并利用建立的优化反应体系和扩增程序对100条候选引物进行筛选。结果表明,适合花吊丝竹的ISSR-PCR反应体系为:20μL的反应液中含3.0 mmol/L Mg~(2+)、0.20 mmol/L d NTPs、1.25 U Taq DNA聚合酶、0.6μmol/L引物、10 ng模板DNA、2μL 10×Buffer、8.55μL dd H_2O。扩增程序为:94℃预变性5 min;94℃变性45 s,52.7℃退火30 s,72℃延伸90 s,40个循环;72℃延伸10 min,4℃保存。建立的花吊丝竹的ISSR-PCR反应体系能够扩增出清晰、多态性较高的条带,且筛选出的16条引物具有高度多态性。表明该体系具有较高的稳定性、重现性和适用性。 相似文献
3.
总结、分析了2019年及近年我国农药登记的基本情况和特点。最近7年来,每年微毒/低毒农药登记数量与当年农药登记总量的比值,及与本年度新增登记数量的比值均持续上升,其比值的年均值分别为82.0%和93.4%;环境友好的剂型在迅速增加,悬浮剂与本年度新增产品登记数量的比值一直处于领先位置,可分散油悬浮剂的比值增长突显,乳油比值在逐年递减;杀虫剂、杀菌剂和除草剂3大类农药登记数量与本年度新增登记数量的比值趋向显著平均;低风险的新农药登记数量在不断增加,生物源农药登记数量增长稳定,5年来其有效成分和产品的年均增长率分别为9.88%和9.46%。从政策和技术上促进特色小宗作物用药登记产品数量快速增加。上述特点表明,我国农药正朝着有利于人畜健康和生态环境安全的方向发展。 相似文献
4.
5.
Race-specificity of temperature-sensitive genes for resistance to Puccinia striiformis in Triticum dicoccoides 总被引:1,自引:0,他引:1
Summary Twenty-four entries of wild emmer possessing temperature-sensitive genes for resistance to yellow rust were studied in the seedling stage, at two temperature-profiles, with 15 pathogenic races from 11 countries in South America, Africa, Asia and Europe. It was shown that the majority of the resistance genes in these wild emmer entries were race-specific. In most of these entries a more resistant reaction was displayed at the higher temperature-profile; however in three entries a shift in reaction towards resistance was observed with certain races but towards susceptibility with some of the other races, suggesting that two different kinds of temperature-sensitive genes were involved in each of these entries. The similarity of temperature-sensitive genes occurring in wild emmer and in cultivated wheat is discussed. 相似文献
6.
Summary S1 to S5 inbred lines, derived from a maize population bred for its overall resistance to three tropical viruses, were screened for resistance to maize streak virus (MSV) by artificial plant infection using viruliferous leafhoppers. Symptoms were rated and intra-line frequency distributions studied for all pedigree inbred lines. Mortality due to MSV was very low among these inbreds. Symptoms appeared later, developed slower and were less severe than in the susceptible control hybrid. Results of a study of 500 S1 and 93 S2 lines suggested that resistance is under genetic control via a system involving loci with major genes (with dominance for resistance) controlling high to complete resistance, associated with a genetic system involving loci with minor genes controlling partial resistance. Lines expressing complete resistance to MSV were developed from 5 cycles of inbreeding and selection. The relevance of such complete and partial resistance is discussed.Abbreviations MRPS
Mean Rating for Plants exhibiting Symptoms 相似文献
7.
J. E. Parlevliet 《Euphytica》1978,27(2):369-379
Summary The latent period (LP) is a crucial component of partial resistance. Five cultivars, L94, Sultan (Su), Volla (Vl), Julia (Ju) and Vada (Va), representing the known range in partial resistance and LP were crossed in a diallel, and the F1, F2 and F3 tested. The LP effectuated by the five cultivars is about 9, 101/2, 101/2, 13 and 151/2 days, respectively. The crosses Su×L94, Vl×L94 and Ju×L94 had an F2 positively skewed. Their F2 means were similar or only slightly larger than the F1 means. The F2 frequency distributions in the crosses Vl×Su, Ju×Su and Ju×Vl were normal or nearly so with F1 and F2 means similar to each other and to the mid-parent value. The crosses involving Va as a parent again showed a positive skewness but with F2 means considerably larger than the F1 moans.Most F2's ranged from the low parent to the high parent values without transgression. In the crosses Va×L94 (reported earlier) and Ju×L94 the parental values were not recovered among 216 and 154 F2 plants, respectively. The cross Ju×Va showed transgression beyond the low parent, Ju.From these data it is concluded, assuming no linkage, that seven loci are involved. The + alleles (governing a longer LP) are thought to be distributed over the parents as follows: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGceaqabeaacaqGmb% GaaeyoaiaabsdacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabcca% caqGGaGaaeiiaiaab2cacaqGTaGaaeiiaiaabccacaqGGaGaaeiiai% aabccacaqGGaGaaeiiaiaabccacaqGTaGaaeylaiaabccacaqGGaGa% aeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeylaiaab2caca% qGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaa% b2cacaqGTaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaae% iiaiaabccacaqGTaGaaeylaiaabccacaqGGaGaaeiiaiaabccacaqG% GaGaaeiiaiaabccacaqGGaGaaeylaiaab2cacaqGGaGaaeiiaiaabc% cacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGTaGaaeyl% aiaabccaaeaacaqGtbGaaeyDaiaabccacaqGGaGaaeiiaiaabccaca% qGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGRaGaae4kaiaa% bccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGRaGaae% 4kaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabUcacaqG% RaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaab2% cacaqGTaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeii% aiaabccacaqGTaGaaeylaiaabccacaqGGaGaaeiiaiaabccacaqGGa% GaaeiiaiaabccacaqGGaGaaeylaiaab2cacaqGGaGaaeiiaiaabcca% caqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGTaGaaeylaa% qaaiaabAfacaqGSbGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqG% GaGaaeiiaiaabccacaqGGaGaaeiiaiaabUcacaqGRaGaaeiiaiaabc% cacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabUcacaqGRaGaaeii% aiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeylaiaab2cacaqGGa% GaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabUca% caqGRaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiai% aab2cacaqGTaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGa% aeiiaiaabccacaqGTaGaaeylaiaabccacaqGGaGaaeiiaiaabccaca% qGGaGaaeiiaiaabccacaqGGaGaaeiiaiaab2cacaqGTaaabaGaaeOs% aiaabwhacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGa% GaaeiiaiaabccacaqGGaGaae4kaiaabUcacaqGGaGaaeiiaiaabcca% caqGGaGaaeiiaiaabccacaqGGaGaae4kaiaabUcacaqGGaGaaeiiai% aabccacaqGGaGaaeiiaiaabccacaqGRaGaae4kaiaabccacaqGGaGa% aeiiaiaabccacaqGGaGaaeiiaiaabccacaqGRaGaae4kaiaabccaca% qGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGRaGaae4kaiaa% bccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaab2cacaqGTaGaae% iiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqG% GaGaaeylaiaab2caaeaacaqGwbGaaeyyaiaabccacaqGGaGaaeiiai% aabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabUcacaqGRaGa% aeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabUcaca% qGRaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaae4kaiaa% bUcacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaae% 4kaiaabUcacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqG% GaGaaeylaiaab2cacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabc% cacaqGGaGaae4kaiaabUcacaqGGaGaaeiiaiaabccacaqGGaGaaeii% aiaabccacaqGGaGaaeiiaiaabUcacaqGRaaaaaa!1BBA!\[\begin{gathered} {\text{L94 - - - - - - - - - - - - - - }} \hfill \\ {\text{Su + + + + + + - - - - - - - - }} \hfill \\ {\text{Vl + + + + - - + + - - - - - - }} \hfill \\ {\text{Ju + + + + + + + + + + - - - - }} \hfill \\ {\text{Va + + + + + + + + - - + + + + }} \hfill \\ \end{gathered} \]The genes are supposed to act additively (intermediate inheritance) with the exception of one locus (the 6th or 7th locus) which shows dominance for the shorter LP (for the-alleles). The effect of this locus on LP seems considerably larger than that of the other loci. There are indications of physiological barriers, which means that LP's shorter than the one of L94 or much longer than that of Va are not possible.The effect of + genes in genotypes governing LP's close to these barriers (with very few or very many + alleles respectively) is smaller than in genotypes governing intermediate LP's. 相似文献
8.
9.
10.