全文获取类型
收费全文 | 89701篇 |
免费 | 5571篇 |
国内免费 | 46篇 |
专业分类
林业 | 3735篇 |
农学 | 3466篇 |
基础科学 | 632篇 |
11246篇 | |
综合类 | 13526篇 |
农作物 | 3359篇 |
水产渔业 | 4936篇 |
畜牧兽医 | 47638篇 |
园艺 | 1165篇 |
植物保护 | 5615篇 |
出版年
2020年 | 733篇 |
2019年 | 953篇 |
2018年 | 1582篇 |
2017年 | 1845篇 |
2016年 | 1660篇 |
2015年 | 1405篇 |
2014年 | 1718篇 |
2013年 | 3717篇 |
2012年 | 2932篇 |
2011年 | 3587篇 |
2010年 | 2339篇 |
2009年 | 2329篇 |
2008年 | 3470篇 |
2007年 | 3209篇 |
2006年 | 3135篇 |
2005年 | 2670篇 |
2004年 | 2577篇 |
2003年 | 2592篇 |
2002年 | 2373篇 |
2001年 | 3389篇 |
2000年 | 3304篇 |
1999年 | 2553篇 |
1998年 | 983篇 |
1997年 | 1051篇 |
1996年 | 883篇 |
1995年 | 1022篇 |
1994年 | 895篇 |
1993年 | 896篇 |
1992年 | 1845篇 |
1991年 | 1919篇 |
1990年 | 1856篇 |
1989年 | 1859篇 |
1988年 | 1607篇 |
1987年 | 1594篇 |
1986年 | 1627篇 |
1985年 | 1526篇 |
1984年 | 1225篇 |
1983年 | 1032篇 |
1982年 | 713篇 |
1979年 | 1060篇 |
1978年 | 816篇 |
1975年 | 815篇 |
1974年 | 897篇 |
1973年 | 864篇 |
1972年 | 805篇 |
1971年 | 795篇 |
1970年 | 800篇 |
1969年 | 780篇 |
1968年 | 708篇 |
1967年 | 734篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
281.
Mixtures of cymoxanil with mancozeb (Mancur) or with mancozeb plus oxadixyl (Pulsan, Sandocur-M) were effective in controlling either metalaxyl-sensitive (MS) or -resistant (MR) isolates ofPseudoperonospora cubensis on cucumbers (cv. ‘Elem’) in growth chambers. Metalaxyl+mancozeb (Ridomil-MZ) and oxadixyl+mancozeb (SAN-518) mixtures were effective against the metalaxyl-sensitive but less so against the metalaxyl-resistant isolate. Fungicide mixtures were far more effective in controlling either the sensitive or the resistant isolates than were the individual components applied alone, thereby representing significant levels of synergistic interactions. Increased efficacy of mixtures relative to their combined components (synergy factor) was calculated by the Wadley method. Mixtures containing cymoxanil showed high synergy factors against the resistant isolate, whereas Ridomil-MZ and SAN-518 did not evince this phenomenon. We concluded that cymoxanil mixtures might be suitable for the control of downy mildew incited by a metalaxyl-resistant isolate ofP. cubensis. 相似文献
282.
283.
284.
In a balance trial with 10 pigs (mean body mass 50 kg) the influence of a bacterial protein supplement (Alcaligenes eutrophus) on N-metabolism was investigated. The bacteria were included into the diet at levels of 7 and 14% at the expense of extracted soyabean meal. Thus bacterial "pure protein" (bacterial non-nucleic acid N X X 6.25) amounted to 30 and 60% of the protein of the ration. Consuming 2 kg of feed dry matter per day the animals of the control group (I) and the experimental groups (II and III) ingested 48 g, 52 g and 55 g of total N respectively. The difference in N-intake is explained by the additional nucleic acid-N, amounting to 19,8% of total bacterial N. Daily weight gain (on average 1054 g) and feed conversion efficiency (feed ingested/weight gain; on average 1,9) were relatively improved at the highest dietary level of bacterial cell mass. Faecal N-excretion was increased significantly, whereas renal N-excretion remained unchanged. Mean apparent N-digestibility was 87,4% showing no significant difference between the experimental groups. N-balance values were noticibly increased following the intake of the bacterial protein supplement. The excretion of urinary urea-N was slightly reduced whereas 4-6 times as much allantoin-N was excreted when bacteria were fed. It is calculated that about 80% of the bacterial purines are renally excreted as allantoin and uric acid. 相似文献
285.
Guttural pouch hemorrhage associated with lesions of the maxillary artery in two horses 总被引:2,自引:2,他引:0 下载免费PDF全文
Smith KM Barber SM 《The Canadian veterinary journal. La revue veterinaire canadienne》1984,25(6):239-242
A two year old Thoroughbred gelding, presented with guttural pouch hemorrhage, had the internal and external carotid arteries ligated. Guttural pouch mycosis was detected on endoscopic examination. After one month of topical antifungal therapy, the horse was returned and euthanized because of recurrent epistaxis. A bacterial infection of the guttural pouch with associated ulceration and hemorrhage from the maxillary artery was found at necropsy.
A two year old grade gelding had ulceration and hemorrhage from the external carotid artery. Utilizing balloon-tipped catheters and arterial ligation, hemestasis was achieved in the internal carotid artery and the external carotid artery and its branches. Mycotic ulceration of the internal carotid artery was detected endoscopically and treated with local antifungal therapy for one month. Thirty-three days postoperatively the horse returned, bleeding from a lesion in the maxillary artery. The rationale for surgical intervention to prevent epistaxis associated with guttural pouch mycosis and possible etiologies for postsurgical epistaxis are discussed.
相似文献286.
Mitcham SA Kasari TR Parent JM Naylor JM 《The Canadian veterinary journal. La revue veterinaire canadienne》1984,25(3):138-141
A nine year old Hereford crossbred cow with a history of progressive neurological signs was referred to the Western College of Veterinary Medicine, Saskatoon. A large intracranial mass, histologically identified as a schwannoma, was found to be compressing the left brain stem and appeared to have arisen from the left fifth cranial nerve. 相似文献
287.
288.
289.
Norris AM Withrow SJ 《The Canadian veterinary journal. La revue veterinaire canadienne》1984,25(4):153-157
A review of the principles of cancer chemotherapy for pet animals is presented. The various pharmacological classes of antineoplastic drugs are described with specific references to those drugs that have been widely used in veterinary medicine. 相似文献
290.
A stranded young pygmy sperm whale was nursed for four days in a pool, fed an artificial diet via a stomach tube and injected intramuscularly with antibiotics and corticosteroids. Initially unable to maintain her balance or to swim, she showed progressive improvement and by the third day could swim and dive quite strongly. Early on the fifth day her condition rapidly worsened and she died. An autopsy revealed extensive deep bruising in the head and mid-abdominal regions consistent with injuries sustained during the stranding. 相似文献