全文获取类型
收费全文 | 173098篇 |
免费 | 9421篇 |
国内免费 | 120篇 |
专业分类
林业 | 7171篇 |
农学 | 5540篇 |
基础科学 | 1051篇 |
21543篇 | |
综合类 | 28997篇 |
农作物 | 6730篇 |
水产渔业 | 8571篇 |
畜牧兽医 | 89293篇 |
园艺 | 2324篇 |
植物保护 | 11419篇 |
出版年
2019年 | 1662篇 |
2018年 | 2552篇 |
2017年 | 2850篇 |
2016年 | 2572篇 |
2015年 | 2204篇 |
2014年 | 2709篇 |
2013年 | 7005篇 |
2012年 | 5091篇 |
2011年 | 6263篇 |
2010年 | 4067篇 |
2009年 | 4141篇 |
2008年 | 6086篇 |
2007年 | 5756篇 |
2006年 | 5434篇 |
2005年 | 5060篇 |
2004年 | 4794篇 |
2003年 | 4945篇 |
2002年 | 4504篇 |
2001年 | 5276篇 |
2000年 | 5309篇 |
1999年 | 4251篇 |
1998年 | 1890篇 |
1997年 | 1788篇 |
1996年 | 1662篇 |
1995年 | 1967篇 |
1994年 | 1777篇 |
1993年 | 1629篇 |
1992年 | 3419篇 |
1991年 | 3611篇 |
1990年 | 3456篇 |
1989年 | 3448篇 |
1988年 | 3153篇 |
1987年 | 3146篇 |
1986年 | 3243篇 |
1985年 | 3186篇 |
1984年 | 2584篇 |
1983年 | 2316篇 |
1982年 | 1568篇 |
1979年 | 2405篇 |
1978年 | 1943篇 |
1977年 | 1681篇 |
1976年 | 1732篇 |
1975年 | 1806篇 |
1974年 | 2145篇 |
1973年 | 2123篇 |
1972年 | 1994篇 |
1971年 | 1850篇 |
1970年 | 1825篇 |
1969年 | 1831篇 |
1967年 | 1626篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
A. Lecoindre D. Saade P. Barthez J. L. Cadoré P. Lecoindre 《The Journal of small animal practice》2018,59(5):311-314
A one‐year‐old female cocker spaniel presented with a 6‐month history of persistent diarrhoea. Abdominal ultrasonographic examination revealed mild diffuse thickening of the intestinal wall coupled with mesenteric lymphadenopathy. A connection between the duodenum and the colon was observed during an endoscopic procedure and confirmed by computed tomography. Surgical resection of the communication allowed remission of the diarrhoea. Histology showed a normal duodenal epithelium and muscular layer. A duodenocolic fistula is an abnormal connection within the digestive tract, which in humans is usually considered a complication of a local pathological condition. Due to the absence of a predisposing cause and, in view of the dog's age and histological results, a congenital origin was suspected. 相似文献
993.
994.
995.
996.
A. Rezaeenia A. A. Naserian R. Valizadeh A. M. Tahmasbi A. Mokhtarpour 《Tropical animal health and production》2018,50(7):1427-1433
The objective of this experiment was to investigate the influence of ground date seed (GDS) on intake, digestibility, and milk yield and milk fatty acid (FA) composition of lactating Holstein cows. The experimental design was a 4?×?4 replicated Latin square with eight lactating dairy cows with an average milk production of 35.5?±?1.5 kg and 75?±?5 days in milk (DIM). Dairy cows were fed one of the four treatments contained 0, 2, 4, and 6% of diet dry matter (DM) GDS in replacement of wheat bran. All diets contained the same amount of forages (alfalfa hay and corn silage). Dietary treatments had no effect on DM intake (DMI), total tract apparent digestibility, milk yield, and milk composition. Increasing GDS linearly decreased concentration of C13:0 and increased cis-9 C14:1 and trans-11 C18:1 (vaccenic acid) (P?<?0.05). A linear tendency for more C16:1 content in milk fat was observed with increasing GDS (P?=?0.06). Feeding GDS resulted in a linear decrease (P?<?0.01) in saturated FA (SFA) but increased milk fat monounsaturated FA (MUFA) and trans FA (TFA) (P?<?0.05). Therefore, low levels of GDS (up to 6%) in the diet of Holstein dairy cows can beneficially modify milk FA composition without any adverse effects on intake, digestibility, and milk yield. 相似文献
997.
Azarpajouh S. Marchewka J. Segura Correa J. C. Calderón Díaz J. A. 《Tropical animal health and production》2018,50(6):1343-1348
Tropical Animal Health and Production - The objective of this study was to compare hoof anatomy, hoof growth pattern, and hoof weight-bearing surface of six different Iranian sheep breeds to... 相似文献
998.
Daniel A. Truchado Michaël A. J. Moens Sergio Callejas Javier Pérez-Tris Laura Benítez 《Veterinary research communications》2018,42(2):111-120
Papillomaviruses are non-enveloped, DNA viruses that infect skin and mucosa of a wide variety of vertebrates, causing neoplasias or simply persisting asymptomatically. Avian papillomaviruses, with six fully sequenced genomes, are the second most studied group after mammalian papillomaviruses. In this study, we describe the first oral avian papillomavirus, detected in the tongue of a dead Yorkshire canary (Serinus canaria) and in oral swabs of the same bird and other two live canaries from an aviary in Madrid, Spain. Its genome is 8,071 bp and presents the canonical papillomavirus architecture with six early (E6, E7, E1, E9, E2, E4) and two late open reading frames (L1 and L2) and a long control region between L1 and E6. This new avian papillomavirus L1 gene shares a 64% pairwise identity with FcPV1 L1, so it has been classified as a new species (ScPV1) within the Ethapapillomavirus genus. Although the canary died after showing breathing problems, there is no evidence that the papillomavirus caused those symptoms so it could be part of the oral microbiota of the birds. Hence, future investigations are needed to evaluate the clinical relevance of the virus. 相似文献
999.
A. O. Lala O. L. Ajayi N. Okwelum A. O. Oso T. V. Fakorede T. A. Adebayo J. E. Jagbojo 《Tropical animal health and production》2018,50(5):1005-1010
The aim of this study was to evaluate the effects of dietary supplementation of Morinda lucida leaf meal (MLLM) on the haematology, biochemical and organ changes of broiler chickens. One hundred and ninety-eight day-old Marshall broiler chicks were completely randomised into 6 treatments in a 3?×?2 factorial arrangement of three levels of M. lucida leaf meal supplementation (0, 0.1 and 0.2 g/kg) with or without medication. The treatment consisted of both negative (without MLLM and routine medication) and positive (containing no MLLM but with routine medication) control groups while each treatment was replicated thrice. MLLM-supplemented diets and routine medication decreased (p?<?0.05) the white blood cell count compared to the negative control. Dietary supplementation with MLLM in combination with normal routine medication increased (p?<?0.05) total serum protein when compared with treatment group without MLLM and routine medication. Dietary supplementation with MLLM and routine medication reduced (p?<?0.05) serum creatinine concentration of the broiler chickens. Birds fed with 0.2 g/kg MLLM supplement coupled with medication and those on negative control had higher (p?<?0.05) creatinine values. Serum enzyme activities reduced (p?<?0.05) following supplementation. MLLM supplementation recorded no significant effect (p?>?0.05) on the liver, kidney, heart and gizzard. M. lucida leaf meal can be compared to routine medication for improved health status of broiler chickens. Dietary inclusion with 0.1 g/kg MLML combined with routine medication could be used in producing healthy and safe chickens. 相似文献
1000.
Pharmacokinetic profiles of the two major active metabolites of metamizole (dipyrone) in cats following three different routes of administration 下载免费PDF全文
B. Lebkowska‐Wieruszewska T. W. Kim B. Chea H. Owen A. Poapolathep M. Giorgi 《Journal of veterinary pharmacology and therapeutics》2018,41(2):334-339
This study was performed to determine pharmacokinetic profiles of the two active metabolites of the analgesic drug metamizole (dipyrone , MET), 4‐methylaminoantipyrine (MAA), and 4‐aminoantipyrine (AA), after intravenous (i.v., intramuscular (i.m.), and oral (p.o.) administration in cats. Six healthy mixed‐breed cats were administered MET (25 mg/kg) by i.v., i.m., or p.o. routes in a crossover design. Adverse clinical signs, namely salivation and vomiting, were detected in all groups (i.v. 67%, i.m. 34%, and p.o. 15%). The mean maximal plasma concentration of MAA for i.v., i.m., and p.o. administrations was 148.63 ± 106.64, 18.74 ± 4.97, and 20.59 ± 15.29 μg/ml, respectively, with about 7 hr of half‐life in all routes. Among the administration routes, the area under the plasma concentration curve (AUC) value was the lowest after i.m. administration and the AUCEV/i.v. ratio was higher in p.o. than the i.m. administration without statistical significance. The plasma concentration of AA was detectable up to 24 hr, and the mean plasma concentrations were smaller than MAA. The present results suggest that MET is converted into the active metabolites in cats as in humans. Further pharmacodynamics and safety studies should be performed before any clinical use. 相似文献