全文获取类型
收费全文 | 926篇 |
免费 | 96篇 |
国内免费 | 85篇 |
专业分类
林业 | 37篇 |
农学 | 23篇 |
基础科学 | 6篇 |
8篇 | |
综合类 | 329篇 |
农作物 | 25篇 |
水产渔业 | 204篇 |
畜牧兽医 | 392篇 |
园艺 | 37篇 |
植物保护 | 46篇 |
出版年
2024年 | 1篇 |
2023年 | 27篇 |
2022年 | 28篇 |
2021年 | 50篇 |
2020年 | 40篇 |
2019年 | 65篇 |
2018年 | 37篇 |
2017年 | 69篇 |
2016年 | 60篇 |
2015年 | 46篇 |
2014年 | 58篇 |
2013年 | 68篇 |
2012年 | 57篇 |
2011年 | 74篇 |
2010年 | 77篇 |
2009年 | 43篇 |
2008年 | 34篇 |
2007年 | 43篇 |
2006年 | 40篇 |
2005年 | 40篇 |
2004年 | 32篇 |
2003年 | 23篇 |
2002年 | 14篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1977年 | 1篇 |
1956年 | 2篇 |
排序方式: 共有1107条查询结果,搜索用时 62 毫秒
101.
中药"乳源康"药理作用研究 总被引:7,自引:1,他引:6
为了对“乳源康”的毒理药理学进行研究,进行4种试验——急性毒性试验、抗菌试验、局部刺激试验、抗炎试验。结果表明,①“乳源康”的小鼠口服LD50为36.80g/kg体重,腹腔注射LD50为13.85g/kg体重;②“乳源康”对乳房炎致病菌金黄色葡萄球菌、链球菌等有较强的抑制作用;③无明显刺激作用;④“乳源康”注射液与氢化可的松的消炎效果相同。“乳源康”治疗奶牛乳房炎具有高效、安全、低毒、使用方便、无化学药物和抗生素残留的优点,临床应用对治疗奶牛乳房炎、解决乳制品中的抗生素类药物残留以及病原微生物的耐药性问题具有重要意义。 相似文献
102.
103.
104.
The present study aimed to investigate the effect of relative humidity(RH) at either acute or chronic moderate ambient temperature(Ta) on growth performance and droppings' corticosterone metabolites of broilers.Two experiments were conducted: effect of RH(35,60 or 85%) on average daily feed intake(ADFI) and droppings' corticosterone metabolites at acute(1 d: 20–26 or 31–20°C,26 or 31°C for 6 h d–1 at 10:00–16:00) moderate Ta(experiment 1) and effect of RH(35,60 or 85%) on growth performance and droppings' corticosterone metabolites at chronic(step-wisely increasing temperature by 3°C every 3 d from 20 to 32°C within 15 d: 20–23–26–29–32°C) moderate Ta(experiment 2).Droppings were collected at the 2,4,6,8,and 22 h after Ta-RH controlled in experiment 1 and at the 2,4,6,and 22 h after Ta controlled to 32°C in experiment 2.The results showed that: 1) In experiment 1,85% RH increased(P0.05) the droppings' corticosterone metabolites at the 2,6,8,and 22 h and 35% RH increased(P0.05) it at the 2 and 22 h compared to the 60% RH.Moreover,85% RH further increased(P0.05) it compared to the 35% RH,however,no difference(P0.05) was found in ADFI among the three RH groups at acute moderate 26°C; 35 and 85% RH increased(P0.05) droppings' corticosterone metabolites at the 2,6,8 and 22 h and decreased(P0.05) ADFI compared to the 60% RH,moreover,85% RH further increased(P0.05) droppings' corticosterone metabolites and further decreased(P0.05) ADFI compared to the 35% RH at acute moderate 31°C; and the average of droppings' corticosterone metabolites in the whole period had a negative correlation(P0.02) with the ADFI.2) In experiment 2,85% RH increased(P0.01) droppings' corticosterone metabolites only at the 2 h and decreased(P0.02) ADFI and average daily gain(ADG) compared to the 60% RH,no difference(P0.05) in droppings' corticosterone metabolites was found between the 35 and 60% RH,however,35% RH decreased(P0.01) ADG compared to the 60% RH,and the average of droppings' corticosterone metabolites in the whole period also had a negative correlation(P0.02) with ADFI and ADG.In conclusion,droppings' corticosterone metabolites could be used as a RH stress index and low and high RH,especially high RH,reduced growth performance possibly through inducing RH stress at moderate temperature. 相似文献
105.
目的 探讨重组组织型纤溶酶原激活物(rtPA)静脉溶栓联合血管内介入治疗(即桥接治疗法)对急性缺血性脑卒中患者的治疗效果。方法 选取我院(2015年1月-2018年1月)收治的100例急性缺血性脑卒中患者进行回顾性分析,根据治疗方法分为观察组47例(桥接治疗法)、对照组53例(rtPA静脉溶栓疗法),对比两组治疗后的血管再通率、神经功能恢复情况。结果 观察组前循环梗死血管(颈内动脉、大脑前动脉、大脑中动脉)再通率91.49%,对照组前循环梗死血管再通率50.94%,两组比较差异具有统计学意义(P<0.01);观察组治疗14 d、治疗28 d、治疗3个月,神经功能缺损(NIHSS)评分均显著的低于对照组(P<0.01);根据mRS标准,观察组的预后良好87.23%,对照组预后良好52.83%,两组比较差异具有统计学意义(P<0.01);观察组的并发症发生率8.51%,对照组并发症发生率16.98%,两组比较差异无统计学意义(P>0.05)。结论 桥接治疗对缺血性脑卒中患者的效果优于rtPA静脉溶栓疗法,对于患者远期神经功能恢复具有显著效果。 相似文献
106.
Yousef Moradi‐Amirabad Heshmat Rahimian Valiollah Babaeizad Sandra Denman 《Forest Pathology》2019,49(4)
Decline diseases of forest trees are complex syndromes not attributable to single causal factors. In Iran, symptoms of decline disease have been observed in a number of native forest species including Quercus castaneifolia (chestnut‐leaved oak), Q. brantii (Persian oak) and Carpinus betulus (hornbeam). The symptoms are prevalent in the northern forests and the Zagros mountain forests. There are parallels between the disease in Iran and acute oak decline (AOD) reported in the UK, specifically the presence of weeping cankers, which have been attributed to a polybacterial complex wherein Brenneria goodwinii is considered a key necrogen. Based on the AOD symptomatology, and as a first step towards discovering potential causal agents of the stem weeping symptoms of affected trees in Iran, necrotic tissues were tested primarily for the presence of B. goodwinii. Symptomatic Q. castaneifolia and C. betulus from the Mazandaran Province and symptomatic Q. brantii from Kohgiluyeh and Boyerahmad Province were sampled. Isolation and culture on a selective medium yielded uniform bacterial colonies. Isolates were characterized using phenotypic and genotypic (DNA sequencing) tests. The isolates were phenotypically identical to members of Pectobacteriaceae and Yersiniaceae, specifically Brenneria and Rahnella spp. The nucleotide sequences of the 16S rRNA and housekeeping genes gyrB, infB and atpD (MLSA) amplified via PCR demonstrated that the isolates from the trees in Iran were indeed B. goodwinii, B. roseae subsp. roseae, Rahnella victoriana and an unknown species of Brenneria. Most bacteria isolated from non‐symptomatic trees were Gram‐positive, and Pseudomonas spp. were dominant, but bacterial species isolated from the diseased trees were not detected in healthy trees. Hypersensitivity response tests were positive, but inoculation on saplings was more variable with internal necrosis developing only once in the test period. Therefore, further testing is required. This is the first report of the incidence of B. goodwinii, B. roseae subsp. roseae, R. victoriana and Brenneria sp. associated with acute oak decline‐like symptoms on Q. castaneifolia, Q. brantii and C. betulus across the western forests of Iran and in the world. 相似文献
107.
108.
109.
110.
蚯蚓是土壤健康的关键指示生物,为了更好地评价草甘膦对土壤无脊椎动物的影响,本研究采用土壤法测定草甘膦对蚯蚓的急性毒性;用不同浓度的草甘膦分别测定不同暴露时间下对蚯蚓超氧化物歧化酶、过氧化氢酶、过氧化物酶、谷胱甘肽S转移酶、乙酰胆碱酯酶活性的影响。结果显示,土壤法测定草甘膦对蚯蚓的LC50>1000 mg/kg;在草甘膦的影响下,随着暴露时间的延长,蚯蚓SOD酶活力有着先增高后下降的趋势,CAT酶活力呈现着先下降后升高的趋势,随着时间和浓度的增长POD酶活力在草甘膦的影响下有逐渐下降的趋势;相对于空白对照,处理组AChE酶活力在草甘膦暴露14 d时显著降低。研究结果将为合理评价和监测草甘膦造成的土壤污染水平提供科学依据。 相似文献