全文获取类型
收费全文 | 2109篇 |
免费 | 124篇 |
国内免费 | 50篇 |
专业分类
林业 | 217篇 |
农学 | 119篇 |
基础科学 | 67篇 |
305篇 | |
综合类 | 487篇 |
农作物 | 77篇 |
水产渔业 | 140篇 |
畜牧兽医 | 696篇 |
园艺 | 65篇 |
植物保护 | 110篇 |
出版年
2023年 | 32篇 |
2022年 | 59篇 |
2021年 | 69篇 |
2020年 | 67篇 |
2019年 | 70篇 |
2018年 | 34篇 |
2017年 | 56篇 |
2016年 | 62篇 |
2015年 | 67篇 |
2014年 | 64篇 |
2013年 | 87篇 |
2012年 | 154篇 |
2011年 | 165篇 |
2010年 | 93篇 |
2009年 | 92篇 |
2008年 | 112篇 |
2007年 | 157篇 |
2006年 | 115篇 |
2005年 | 89篇 |
2004年 | 81篇 |
2003年 | 79篇 |
2002年 | 67篇 |
2001年 | 40篇 |
2000年 | 32篇 |
1999年 | 36篇 |
1998年 | 27篇 |
1997年 | 15篇 |
1996年 | 14篇 |
1995年 | 11篇 |
1994年 | 13篇 |
1993年 | 13篇 |
1992年 | 10篇 |
1991年 | 9篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1988年 | 14篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1981年 | 9篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1975年 | 5篇 |
1970年 | 7篇 |
1969年 | 7篇 |
1934年 | 5篇 |
1933年 | 8篇 |
1932年 | 8篇 |
1931年 | 5篇 |
排序方式: 共有2283条查询结果,搜索用时 0 毫秒
61.
62.
63.
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
64.
8个微卫星座位在海北金银滩藏羊群体中的多态性分析 总被引:1,自引:0,他引:1
研究旨在分析金银滩藏羊的微卫星DNA多态性,以期了解该品种的遗传多样性,为该品种的保种选育和品质的进一步提高提供有益资料。利用8对微卫星引物,以金银滩藏羊为研究对象,通过计算基因频率、多态性信息含量、有效等位基因数和杂合度,评估其品种内的遗传变异。结果表明:在8个微卫星座位中,共检测到83个等位基因,每个座位平均10.38个等位基因;平均杂合度0.893;平均有效等位基因数9.06;平均多态性信息含量0.871。结果提示,金银滩藏羊群体存在丰富的遗传多样性,所选微卫星标记可用于绵羊遗传多样性评估。 相似文献
65.
Jason E. Anton Kristine L. Vernon Dale E. Kelley John R. Gibbons Glen Birrenkott Chris J. Mortensen 《Journal of Equine Veterinary Science》2014
Our previous research has demonstrated moderate exercise can be detrimental to early pregnancy in the mare, but little work has examined exercise after pregnancy has been detected. We exercised mares (n = 8) 6 days a week for 45 min from Day 16 until Day 80 of gestation. Color Doppler ultrasonography was used to evaluate embryonic vesicle size, fetal length, and uterine blood flow. Blood was sampled every other day to analyze cortisol and progesterone concentrations. Results indicated that exercising pregnant mares (n = 4) led to greater (P < .01) cortisol concentrations 30 min after the exercise period. No overall treatment effect could be detected in progesterone concentrations; however, following Day 60 of gestation, progesterone concentrations were lower (P < .05) in exercised mares. Additionally, progesterone concentrations peaked earlier in exercised mares at Day 52 of gestation compared to peak levels at Day 68 of gestation for control mares. No significant effects were detected in embryonic vesicle size. Fetal length tended (P = .06) to be longer in the conceptus of exercised mares. Uterine blood flow did not differ between groups but increased as pregnancy progressed (P < .001) in both groups. All mares in this study went on to deliver healthy foals and suffered no difficulties during parturition. These results indicated that moderate exercise was not detrimental to mare pregnancy. 相似文献
66.
A new antiepileptic and anxiolytic drug, ELB138, was evaluated in a clinical pilot study in dogs with newly diagnosed or chronic idiopathic epilepsy. The purpose was to verify clinically the anticonvulsant effectiveness of this substance, which had already been demonstrated experimentally. Data from 29 dogs treated with ELB138 were compared with results obtained retrospectively from 82 dogs treated with conventional antiepileptic medication. The reduction in seizure frequency using ELB138 in dogs with newly diagnosed idiopathic epilepsy was comparable to the reduction in dogs treated either with phenobarbital or primidone. In dogs with chronic epilepsy and add-on therapy with either ELB138 or potassium bromide, such supplementation reduced the seizure frequency and the duration and severity of seizures. The most obvious difference between ELB138 treatment and conventional medications became clear in the evaluation of side effects, which in those dogs treated with ELB138 were rare, and consisted mostly of transient polyphagia. This pilot study confirmed that ELB138 has a potent anticonvulsant effect in dogs with idiopathic epilepsy. These results will form the basis for a multicentre, blinded study. 相似文献
67.
Peter M. Visscher Naomi R. Wray Chris S. Haley 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2019,136(4):273-278
Through his own research contributions on the modelling and genetic analysis of quantitative traits and through his former students and postdocs, Robin Thompson has indirectly left a major legacy in human genetics. In this short note, we highlight examples of the long‐lasting relevance and impact of Robin's work in human genetics. A lone early study of marker‐assisted selection developed many of the tools and approaches later exploited (often after reinvention) by the human genetics community in GWAS studies and for prediction. Furthermore, a particularly clear example of the pervasive impact of Robin's work is that REML has become the default method to estimate variance components and that genetic predictions exploiting linkage disequilibrium in the population are starting to become used in precision medicine applications. 相似文献
68.
Isabelle A. Kagan Brett H. Kirch Craig D. Thatcher James R. Strickland Chris D. Teutsch François Elvinger R. Scott Pleasant 《Journal of Equine Veterinary Science》2011,31(8):488-497
Seasonal and diurnal changes in water-soluble carbohydrates (WSC) and ethanol-soluble carbohydrates (ESC), as well as in chromatographic profiles of the sugars comprising these categories, were studied in orchardgrass pastures at one location in the Piedmont region of Virginia. Grass from four experimental plots was sampled weekly in the morning and afternoon over an 8-week period (early to late spring). Tissue was air-dried to simulate hay, or frozen to preserve the sugar profiles of fresh pasture. WSC and ESC were assayed colorimetrically. To profile sugars, boiled-water extracts were separated by high-performance liquid chromatography coupled to pulsed amperometric detection. Fructan, glucose, fructose, and sucrose were quantified by high-performance liquid chromatography. All sugar concentrations were highest in the early spring in both fresh and dried tissue. Fructan chain length was highest in early spring as well. Significant diurnal differences were observed for WSC and fructan, on some dates (P < .0001 and P = .024, respectively), and for ESC, glucose, and sucrose averaged over the entire period (P = .0002, .004, and <.0001, respectively). Sucrose was barely detectable in fresh tissue but reached 1.6% to 12% dry matter in dried tissue. These results demonstrate changes in orchardgrass carbohydrates over a season, within a day, and between dried and fresh herbage. Understanding these changes may be helpful in the management of horses with a history of insulin resistance and laminitis. 相似文献
69.
Isabelle Ann Kagan PhD Brett H. Kirch DVM PhD Craig D. Thatcher DVM PhD Chris D. Teutsch PhD François Elvinger Dr Med Vet PhD Dare M. Shepherd BS Scott Pleasant DVM MS 《Journal of Equine Veterinary Science》2011,31(9):521-529
Seasonal and diurnal patterns of sugar accumulation in bermudagrass (Cynodon dactylon) pastures were monitored to evaluate risk factors for pasture-associated laminitis of ponies and horses. Bermudagrass was collected from four plots in the morning and afternoon on a weekly basis, from mid-July until late August. Tissue was air-dried to simulate hay, or frozen to retain the sugar profiles of fresh pasture. Samples were analyzed colorimetrically for total water-soluble and ethanol-soluble carbohydrates, and electrochemically for starch. In addition, sugars were separated and quantified by high-performance liquid chromatography coupled to pulsed amperometric detection. The dominant sugars in extracts were glucose, fructose, and sucrose. Some minor peaks, corresponding to tri- and tetrasaccharides, were also detected in some extracts. Starch increased over time in fresh and dried tissue, and concentrations varied diurnally in fresh, but not in dried tissue (P = .021). Sucrose in dried tissue decreased and then increased, with higher concentrations than in fresh tissue on all sampling dates (P = .024). Glucose and fructose exhibited diurnal variation on one and two dates, respectively (P = .034 and .0028, respectively). These results reveal trends in carbohydrate concentrations and profiles that may help to evaluate the likelihood of equine laminitis outbreaks on bermudagrass. 相似文献
70.
A 13-year-old, female Llama presented for evaluation of a limbal based corneal mass involving the OD of 4 months duration. The mass was excised en bloc by a nonpenetrating keratectomy, followed by placement of a conjunctival advancement flap covering the keratectomy site. The mass was submitted for histological evaluation. Histopathology identified the mass to be a corneal epithelial inclusion cyst filled with necrotic squamous and neutrophilic debris. Surgical excision was complete and considered curative with no signs of recurrence 3 months postoperatively. There was no known prior ocular trauma; however, a previously performed corneal biopsy for evaluation of recurrent epithelial erosions may have been an initiating cause. 相似文献