全文获取类型
收费全文 | 436篇 |
免费 | 30篇 |
专业分类
林业 | 2篇 |
农学 | 9篇 |
27篇 | |
综合类 | 59篇 |
农作物 | 47篇 |
水产渔业 | 40篇 |
畜牧兽医 | 256篇 |
园艺 | 15篇 |
植物保护 | 11篇 |
出版年
2020年 | 13篇 |
2019年 | 6篇 |
2018年 | 10篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 7篇 |
2014年 | 7篇 |
2013年 | 25篇 |
2012年 | 16篇 |
2011年 | 14篇 |
2008年 | 21篇 |
2007年 | 12篇 |
2006年 | 18篇 |
2005年 | 8篇 |
2004年 | 16篇 |
2003年 | 9篇 |
2002年 | 5篇 |
2001年 | 19篇 |
1999年 | 11篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1993年 | 9篇 |
1992年 | 8篇 |
1991年 | 8篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 10篇 |
1985年 | 4篇 |
1984年 | 7篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1975年 | 5篇 |
1974年 | 11篇 |
1973年 | 4篇 |
1971年 | 7篇 |
1968年 | 8篇 |
1966年 | 5篇 |
1939年 | 3篇 |
1937年 | 3篇 |
1936年 | 5篇 |
1935年 | 5篇 |
1934年 | 5篇 |
1930年 | 3篇 |
1926年 | 3篇 |
1925年 | 3篇 |
1924年 | 6篇 |
排序方式: 共有466条查询结果,搜索用时 156 毫秒
11.
Antoine LF Gady Freddy WK Hermans Marion HBJ Van de Wal Eibertus N van Loo Richard GF Visser Christian WB Bachem 《Plant methods》2009,5(1):13-14
Background
The establishment of mutant populations together with the strategies for targeted mutation detection has been applied successfully to a large number of organisms including many species in the plant kingdom. Considerable efforts have been invested into research on tomato as a model for berry-fruit plants. With the progress of the tomato sequencing project, reverse genetics becomes an obvious and achievable goal. 相似文献12.
13.
Claude E. Boyd Craig S. Tucker Benjaporn Somridhivej 《Journal of the World Aquaculture Society》2016,47(1):6-41
Total alkalinity and total hardness are familiar variables in aquatic animal production. Aquaculturists—both scientists and practitioners alike—have some understanding of the two variables and of methods for adjusting their concentrations. The chemistry and the biological effects of alkalinity and hardness, however, are more complex than generally realized or depicted in the aquaculture literature. Moreover, the discussions of alkalinity and hardness—alkalinity in particular—found in water chemistry texts are presented in a rigorous manner and without explanation of how the two variables relate to aquaculture. This review provides a thorough but less rigorous discussion of alkalinity and hardness specifically oriented toward aquaculture. Alkalinity and hardness are defined, their sources identified, and analytical methods explained. This is followed by a discussion of the roles of the two variables in aquaculture, including their relationships with carbon dioxide, pH, atmospheric pollution, ammonia, and other inorganic nitrogen compounds, phytoplankton communities, trace metals, animal physiology, and clay turbidity. Liming and other practices to manage alkalinity and hardness are explained. Changes in alkalinity and hardness concentrations that occur over time in aquaculture systems are discussed. Emphasis is placed on interactions among alkalinity, hardness, water quality, and aquacultural production. 相似文献
14.
15.
J J Hoskinson R L Tucker 《Veterinary Clinics of North America: Small Animal Practice》2001,31(1):165-80, vii
The demand for advanced diagnostic imaging procedures such as nuclear scintigraphy, ultrasonography, computed tomography, and magnetic resonance imaging has increased dramatically over the past 10 years. Veterinarians, seeking to improve their diagnostic capabilities and clients willing to pursue "best medicine" have driven this demand, resulting in installation of advanced imaging facilities at most academic and private referral practices. Knowledge of potential benefits of various modalities will allow the veterinarian to optimize his or her use of diagnostic imaging in his or her own practice or in a referral practice. 相似文献
16.
McMahon CD Chapin LT Lookingland KJ Radcliff RP Tucker HA 《Domestic animal endocrinology》1999,17(4):439-447
Secretion of growth hormone (GH) is reduced for several hours after feeding when access to feed is restricted to a 2-hr period each day. We hypothesized that increased secretion of insulin after feeding inhibits release of GH from the anterior pituitary gland. Our objectives were to determine whether: 1) alloxan prevents concentrations of insulin from increasing after feeding steers; 2) concentrations of GH remain high after feeding alloxan-treated steers; and 3) GH-releasing hormone (GHRH) stimulates greater release of GH in alloxan-treated, than in control, steers after feeding. Steers were injected iv with either saline (control) or with alloxan (110 mg/kg) (n = 4 per group). Concentrations of insulin were not different (P = 0.61) between control and alloxan-treated steers before feeding (87.5 +/- 33.6 pmol/l). However, alloxan prevented insulin from increasing (P < 0.001) after feeding (131.8 pmol/1) compared with control steers (442.0 pmol/l) (pooled SEM = 47.5). Overall, GH was higher (P < 0.05) in alloxan-treated (6.4 ng/ml) than in control steers (3.7 ng/ml) (pooled SEM = 0.7), but GH decreased (P < 0.001) after feeding in both groups. Iv injection of GHRH stimulated release of GH 1 hr before, but not when injected 1 hr after feeding (P < 0.001). In addition, net areas under the GH curve were not significantly different between control and alloxan-treated groups. We conclude that increased concentrations of insulin after feeding do not mediate feeding-induced suppression of GH secretion in steers. 相似文献
17.
Comparisons were made between diameters of 54 bovine follicles greater than 5.9 mm from 32 pairs of ovaries measured on the ovarian surface and diameters of the same follicles subsequently dissected from the ovaries. Seventy-eight percent of follicles measured on the ovarian surface were within 1.9 mm of the size measured after dissection. The remaining 22% of follicles measured on the surface had diameters recorded that were 2.0 to 3.9 mm different than their diameter after dissection. Surface diameter tended to underestimate dissected diameter for small follicles (less than 8.0 mm) and to overestimate dissected diameter for large (greater than or equal to 12.0 mm) follicles. The correlation coefficient between surface and dissected follicular diameters was .83. We conclude that measuring the diameter of the largest follicles on the ovarian surface and after dissection yield approximately equivalent results. 相似文献
18.
19.
Methyl bromide, used at a concentration‐time product of 800 mg h/l at 25 °C with a relative humidity of 70%, was successful in eliminating salmonellae from artificially contaminated poultry foodstuffs. Chicks fed on this fumigated food remained free from the infection and there were no adverse effects on growth rate. 相似文献
20.
Grubbs ST Amodie D Rulli D Wulster-Radcliffe M Reinemeyer C Yazwinski T Tucker C Hutchens D Smith L Patterson D 《Veterinary therapeutics : research in applied veterinary medicine》2003,4(3):249-256
The safety and efficacy of 2% moxidectin/12.5% praziquantel oral gel administered at a rate of 0.4 mg moxidectin and 2.5 mg praziquantel/kg was studied in client-owned horses under field use conditions. Four hundred horses (300 treated with moxidectin/praziquantel oral gel and 100 treated with vehicle) were enrolled, feces were collected, and eggs were counted. Investigators as well as horse owners were masked to treatment assignment. No adverse reactions to treatment were observed in any horses. Moxidectin/praziquantel gel reduced Anoplocephala spp by more than 99% and provided a significant (P <.05) reduction (> 98%) in the strongyle egg count of treated horses. 相似文献