全文获取类型
收费全文 | 1552篇 |
免费 | 81篇 |
国内免费 | 3篇 |
专业分类
林业 | 58篇 |
农学 | 33篇 |
基础科学 | 5篇 |
157篇 | |
综合类 | 250篇 |
农作物 | 86篇 |
水产渔业 | 168篇 |
畜牧兽医 | 804篇 |
园艺 | 39篇 |
植物保护 | 36篇 |
出版年
2021年 | 28篇 |
2020年 | 34篇 |
2019年 | 34篇 |
2018年 | 32篇 |
2017年 | 39篇 |
2016年 | 38篇 |
2015年 | 28篇 |
2014年 | 30篇 |
2013年 | 69篇 |
2012年 | 81篇 |
2011年 | 87篇 |
2010年 | 47篇 |
2009年 | 38篇 |
2008年 | 78篇 |
2007年 | 77篇 |
2006年 | 97篇 |
2005年 | 67篇 |
2004年 | 71篇 |
2003年 | 62篇 |
2002年 | 68篇 |
2001年 | 45篇 |
2000年 | 14篇 |
1999年 | 23篇 |
1998年 | 7篇 |
1997年 | 10篇 |
1996年 | 15篇 |
1995年 | 15篇 |
1994年 | 9篇 |
1993年 | 18篇 |
1992年 | 21篇 |
1991年 | 19篇 |
1990年 | 13篇 |
1989年 | 13篇 |
1988年 | 14篇 |
1987年 | 16篇 |
1986年 | 20篇 |
1985年 | 14篇 |
1984年 | 14篇 |
1983年 | 10篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1974年 | 13篇 |
1972年 | 9篇 |
1971年 | 9篇 |
1968年 | 12篇 |
1967年 | 6篇 |
1966年 | 7篇 |
1936年 | 8篇 |
1935年 | 7篇 |
1924年 | 6篇 |
排序方式: 共有1636条查询结果,搜索用时 0 毫秒
101.
1. The role of certain fish meals in the production of localised gizzard erosion is confirmed.
2. Lesions typical of gizzard erosion could be produced by the addition of histamine to the diet.
3. The amount of histamine occurring naturally in fish meal depends on the species of fish and the extent and nature of bacterial spoilage.
4. These variables may explain why histamine has not been implicated previously and also why there have not been consistent associations between the condition and geographical source or common factors in bulk consignments of the meal. 相似文献
102.
103.
Kristene R. Gedye Arthur D. Bettge Garrison E. King Craig F. Morris 《Euphytica》2005,141(1-2):121-127
Kernel texture is an important characteristic for both the milling and the end-use quality of wheat (Triticum aestivum L.). Gene sequence variation and mutations to the two puroindoline genes (Pina and Pinb), located at the Ha locus on chromosome 5DS, account for the majority of variation in wheat kernel texture. Other factors also influence kernel texture, including effects associated with different maternal parent backgrounds. To investigate the effect of two hard puroindoline alleles in different maternal backgrounds, a population of 228 recombinant inbred lines (RILs) derived from a reciprocal cross between two wheat cultivars ID377s (Pina-D1b/Pinb-D1a) and Klasic (Pina-D1a/Pinb-D1b) were examined in two succeeding generations (F7 & F8). Kernel texture was determined using the Single Kernel Characterization System (SKCS) and the RIL puroindoline haplotype was identified by the sequence-specific PCR amplification of each gene. Analysis of variance identified a significant (P 0.001) effect of the maternal parent and puroindoline mutation on kernel texture. RILs containing the Pina-D1b mutation were significantly harder than lines containing the Pinb-D1b mutation. RILs which had Klasic as the maternal parent were significantly harder than those which had ID377s as the maternal parent. When the maternal parent and puroindoline allele were analyzed in combination, RILs derived from Klasic as the maternal parent and the Pina-D1b allele were significantly harder (P 0.001) than those containing the same allele but ID377s as the maternal parent. The same occurred for RILs containing the Pinb-D1b allele, lines with Klasic as the maternal parent were harder than lines with ID377s as the maternal parent. These results corroborate the harder phenotype of the Pina-D1b allele and indicate a significant maternally-inherited contribution to kernel texture variation. 相似文献
104.
To examine ovarian follicular response to low-dose injections of luteinizing hormone-releasing hormone (LHRH), 32 anovulatory, suckled beef cows were allotted to one of four treatment groups and injected with either saline or 500 ng LHRH every 2 h for 48 or 96 h, starting 21.4 +/- .4 d after parturition. Two hours after the last injection of LHRH, cows were ovariectomized and 10 to 15 ovarian follicles per pair of ovaries were removed and categorized by diameter as small (1.0 to 3.9 mm), medium (4.0 to 7.9 mm) or large (greater than or equal to 8.0 mm). Injections of LHRH did not affect (P greater than .10) steroid levels in small follicles or numbers of gonadotropin receptors in small and medium follicles. Concentrations of progesterone in fluid of medium follicles increased 1.5-fold (P less than .05) after 96 h of LHRH, whereas concentrations of estradiol and androstenedione were unchanged. In fluid of large follicles, concentrations of progesterone were fourfold greater (P less than .05) in LHRH-treated than in control cows at 48 h, but by 96 h progesterone was twofold greater (P less than .05) in control than LHRH-treated cows. In large follicles, concentrations of estradiol were unchanged (P greater than .10) after 48 h of LHRH injections but after 96 h estradiol was twofold greater (P less than .05) in LHRH-treated than control cows. Increased concentrations of estradiol in large follicles coincided with increased numbers of binding sites for human chorionic gonadotropin (hCG) but not follicle stimulating hormone (FSH) in granulosa and theca.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
105.
106.
Infarction of the pons and rostral medulla secondary to arteriolar thrombosis was documented histologically in a 17-year-old mixed-Arabian female horse. Clinically, the animal experienced a sudden onset of a head tilt and subsequent non-controllable seizures. There was no historical, clinical or histological evidence to suggest the presence of infection of Equine Herpesvirus-1 or the feeding of corn contaminated by Fusarium moniliforme. 相似文献
107.
M. P. Reichel D. J. Baber P. S. Craig R. B. Gasser 《Preventive veterinary medicine》1996,27(3-4):115-123
From 1991 to 1993, an investigation into the epidemiology of cystic echinococcosis (CE) was carried out in the Falkland Islands to evaluate the progress of the hydatid eradication campaign. The prevalence of CE in sheep was assessed using abattoir and farm slaughter data, and the exposure of dogs to the parasite was estimated using immunological techniques. A total of 59 466 sheep was examined at slaughter for E. granulosus and T. hydatigena cysts and the entire dog population of the Falkland Islands (n = 908) was examined by ELISA for the presence of specific serum antibodies to E. granulosus (IgG, IgA and IgE). In addition, a subsample of dogs (n = 464) was tested for the presence of E. granulosus antigens in faeces (copro-antigens). The prevalence of CE in sheep increased significantly during the period of the study from 0.11% in 1991 to 0.47% in 1993. Nineteen (2.1%) of 908 dog sera tested were seropositive, and eight dogs (1.7%) of 464 tested were positive in the copro-antigen assay. The combined use of abattoir surveillance, specific antibody and copro-antigen assay suggested that there were several locations in the Falkland Islands where the life cycle of E. granulosus may still perpetuate. Specific deficiencies in the eradication effort in those locations could be identified through follow-up questionnaires. 相似文献
108.
109.
There is a growing interest in the use of computed tomography (CT) and magnetic resonance (MR) imaging in equine orthopedic patients. It is well established that CT and MR imaging offer superior diagnostic information in a wide variety of musculoskeletal injuries in human beings and small animals. The highly detailed cross-sectional images obtained with these two modalities can often demonstrate pathologic changes undetected with other common imaging techniques. Based on their multiple applications in human beings and small animals, CT or MR imaging may prove to be the optimal diagnostic imaging technique for several types of musculoskeletal disorders of horses. 相似文献
110.
K. Jane Wardrop DVM MS Russell L. Tucker Kristen Mugnai 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1997,11(1):5-8
An additive solution for the storage of red blood cells was evaluated for use in dogs. Blood collected from 6 dogs was processed into packed red blood cells and stored for 35 days in the additive solution Nutricel (Miles, Inc, Pharmaceutical Division, West Haven, CT). Packed red blood cells stored in citrate-phosphate-dextrose-adenine (CPDA-1; Fenwal Laboratories, Baxter Health Care Corp, Deerfield, IL) also were evaluated for comparison. Red blood cell 2,3-diphosphoglycerate (2,3-DPG) concentration, adenosine triphosphate (ATP) concentration, percentage hemolysis, and pH were determined. The red blood cell post-transfusion viability (PTV) after 35 days of storage was assessed with both single-labeled chromium 51 (51Cr) and double-labeled technetium 99m/chromium 51 (99mTc/51Cr) techniques. Mean ATP concentration and percentage hemolysis of the cells stored in Nutricel were 1.1 μmol/g hemoglobin (Hb) and 0.28% respectively and did not differ significantly (P < .05) from the values of 1.0 μmol/g Hb and 0.33% from the CPDA-1-stored red blood cells. The mean pH of red blood cells stored in Nutricel was 6.19, which was significantly lower than the pH of 6.47 for cells stored in CPDA-1. The mean 2,3-DPG concentration of red blood cells stored in Nutricel was significantly higher at 10.1 μmol/g Hb than the 2,3-DPG concentration of 3.4μmol/g Hb for cells stored in CPDA-1. The mean PTV of canine red blood cells stored in Nutricel for 35 days was 85% with 51Cr and 90% with 99mTc/51Cr. This was significantly higher than the mean PTVs of 38% and 36% for the CPDA-1 stored cells as assessed with 51Cr and 99mTc/51Cr techniques, respectively. It was concluded that 35-day-old canine red blood cells stored in Nutricel are of acceptable quality for transfusion purposes. 相似文献