全文获取类型
收费全文 | 272篇 |
免费 | 32篇 |
专业分类
林业 | 17篇 |
农学 | 4篇 |
55篇 | |
综合类 | 16篇 |
农作物 | 9篇 |
水产渔业 | 14篇 |
畜牧兽医 | 162篇 |
园艺 | 1篇 |
植物保护 | 26篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 19篇 |
2019年 | 18篇 |
2018年 | 10篇 |
2017年 | 16篇 |
2016年 | 14篇 |
2015年 | 10篇 |
2014年 | 21篇 |
2013年 | 28篇 |
2012年 | 37篇 |
2011年 | 22篇 |
2010年 | 13篇 |
2009年 | 9篇 |
2008年 | 10篇 |
2007年 | 19篇 |
2006年 | 6篇 |
2005年 | 5篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 9篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1998年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1990年 | 1篇 |
1979年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有304条查询结果,搜索用时 343 毫秒
181.
Maitland Danielle M. Baker Joe Chambers Greg Ross Neil W. Colombo Stefanie M. 《Aquaculture International》2022,30(1):187-210
Aquaculture International - Information on growth dynamics of koi grown long-term in recirculating aquaculture systems (RAS) is lacking. The objective of this study was to establish baseline... 相似文献
182.
Ralph A Lloyd‐Edwards Dorien S Willems Martijn Beukers Astrid van den Brom‐Spierenburg Johannes C M Vernooij Stefanie Veraa 《Veterinary radiology & ultrasound》2020,61(3):269-278
Cholesterinic granulomas are mass‐like lesions that form at the choroid plexus of the ventricular system. Large cholesterinic granulomas within the lateral ventricles have been reported to cause severe neurological signs. However, little data are available about their prevalence or appearance in the overall population. The objective was to report the prevalence of presumed cholesterinic granulomas on CT in a population of horses, and investigate associations between presumed cholesterinic granuloma presence, lateral ventricle size, age, and neurological signs. The study was cross sectional, CT scans of the head were assessed for presumed cholesterinic granuloma presence and size, and lateral ventricle height. Computed tomography findings and clinical information were compared using nonparametric testing. Computed tomography scans of 139 horses were included. Presumed cholesterinic granulomas were found in 22 horses (15.8%), nine were unilateral and 13 bilateral. A significant increase in prevalence was observed with age (P < .0001), with 38% of horses over 15 years old affected. The median volume of presumed cholesterinic granulomas was 242 mm3 with a range from 51 to 2420 mm3. The mean lateral ventricle height was significantly increased in horses with presumed cholesterinic granulomas present (P = .004), with a median of 7.3 mm compared to 4.9 mm without. Neurological signs were not associated with presumed cholesterinic granuloma presence or lateral ventricle height. Fourth ventricle mineralizations were found in seven horses, which may represent cholesterinic granulomas. In conclusion, presumed cholesterinic granulomas occurred in a large proportion of the examined population and are associated with increased lateral ventricle dilation and advanced age. 相似文献
183.
184.
Hata Y Zimmermann S Quitschau M Kaiser M Hamburger M Adams M 《Journal of agricultural and food chemistry》2011,59(17):9172-9176
In a screen of 1800 plant and fungal extracts for antiplasmodial, antitrypanosomal, and leishmanicidal activity, the n-hexane extract of Chrysanthemum cinerariifolium (Trevir.) Vis. flowers showed strong activity against Plasmodium falciparum. We isolated the five pyrethrins [i.e., pyrethrin II (1), jasmolin II (2), cinerin II (3), pyrethrin I (4), and jasmolin I (5)] from this extract. These were tested together with 15 synthetic pyrethroids for their activity against P. falciparum and Trypanosoma brucei rhodesiense and for cytotoxicity in rat myoblast L6 cells. The natural pyrethrins showed antiplasmodial activity with IC(50)s between 4 and 12 μM, and antitrypanosomal activity with IC(50)s from 7 to 31 μM. The pyrethroids exhibited weaker antiplasmodial and antitrypanosomal activity than the pyrethrins. Both pyrethrins and pyrethroids showed moderate cytotoxicity against L6 cells. Pyrethrin II (1) was the most selective antiplasmodial compound, with a selectivity index of 24. 相似文献
185.
Neurons in the human central nervous system (CNS) are unable to regenerate, as a result of both an inhibitory environment and their inherent inability to regrow. In contrast, the CNS environment in fish is permissive for growth, yet some neurons still cannot regenerate. Fish thus offer an opportunity to study molecules that might surmount the intrinsic limitations they share with mammals, without the complication of an inhibitory environment. We show by in vivo imaging in zebrafish that post-injury application of cyclic adenosine monophosphate can transform severed CNS neurons into ones that regenerate and restore function, thus overcoming intrinsic limitations to regeneration in a vertebrate. 相似文献
186.
187.
188.
Gregório M. Oliveira Júnior Aloízio S. Ferreira Valéria V. Rodrigues Érika M. Figueiredo Andressa S. Formigoni Márcio G. Zangeronimo Wilams G. Santos Renata R. Alvarenga 《Animal Science Journal》2014,85(5):602-610
The objective of this study was to evaluate the behavior and performance of sows and piglets kept in different types of farrowing rooms: conventional farrowing room with jugglers and cages (CFR), CFR with a heated floor for the piglets alongside the sows (CFR+HF) and semi‐outdoor farrowing room without a cage or heating floor but with access to a fenced field (SFR) during the tropical winter. Twenty‐seven multiparous sows were allocated in three treatments and nine repetitions during 21 days. The relative humidity was higher at CFR and CFR+HF. The temperature of thigh and chest in contact with the floor and the neck were higher (P < 0.01) in conventional systems. Sows maintained in the CFR spent (P < 0.01) more time feeding and drinking. The heating floor increased (P < 0.01) the nursing behavior but did not affect (P > 0.09) the sows’ and piglets’ performances. SFR decreased the backfat thickness (P = 0.03) and lactation efficiency, but did not affect milk production (P > 0.12) or piglet performance (P > 0.09). It is concluded that during tropical winter, conventional farrowing systems ensure better piglet performance compared to SFR but this last seems to improve the behavior of sows. The heating floor favors nursing and does not affect the welfare of sows. 相似文献
189.
Differences in the isotopic signature of organic matter between soil fractions are indicative of transformation and ageing processes. Here we show that with increasing microbial transformation measured by δ15N, there is a concomitant increase in carbon age as measured by 14C. The age of the soil's heavy fraction further increases with microbial utilization, indicating that stabilized OM ages yet continues to be reused. 相似文献
190.
K. D. Niswender M. A. Alvarenga P. M. McCue Q. P. Hardy E. L. Squires 《Journal of Equine Veterinary Science》2003,23(11):497-500
Superovulation would potentially increase the efficiency and decrease the cost of embryo transfer by increasing embryo collection rates. Other potential clinical applications include improving pregnancy rates from frozen semen, treatment of subfertility in stallions and mares, and induction of ovulation in transitional mares. The objective of this study was to evaluate the efficacy of purified equine follicle stimulating hormone (eFSH; Bioniche Animal Health USA, Inc., Athens, GA) in inducing superovulation in cycling mares. In the first experiment, 49 normal, cycling mares were used in a study at Colorado State University. Mares were assigned to 1 of 3 groups: group 1, controls (n = 29) and groups 2 and 3, eFSH-treated (n = 10/group). Treated mares were administered 25 mg of eFSH twice daily beginning 5 or 6 days after ovulation (group 2). Mares received 250 (of cloprostenol on the second day of eFSH treatment. Administration of eFSH continued until the majority of follicles reached a diameter of 35 mm, at which time a deslorelin implant was administered. Group 3 mares (n = 10) received 12 mg of eFSH twice daily starting on day 5 or 6. The treatment regimen was identical to that of group 2. Mares in all 3 groups were bred with semen from 1 of 4 stallions. Pregnancy status was determined at 14 to 16 days after ovulation.In experiment 2, 16 light-horse mares were used during the physiologic breeding season in Brazil. On the first cycle, mares served as controls, and on the second cycle, mares were administered 12 mg of eFSH twice daily until a majority of follicles were 35 mm in diameter, at which time human chorionic gonadotropin (hCG) was administered. Mares were inseminated on both cycles, and embryo collection attempts were performed 7 or 8 days after ovulation.Mares treated with 25 mg of eFSH developed a greater number of follicles (35 mm) and ovulated a greater number of follicles than control mares. However, the number of pregnancies obtained per mare was not different between control mares and those receiving 25 mg of eFSH twice daily. Mares treated with 12 mg of eFSH and administered either hCG or deslorelin also developed more follicles than untreated controls. Mares receiving eFSH followed by hCG ovulated a greater number of follicles than control mares, whereas the number of ovulations from mares receiving eFSH followed by deslorelin was similar to that of control mares. Pregnancy rate for mares induced to ovulate with hCG was higher than that of control mares, whereas the pregnancy rate for eFSH-treated mares induced to ovulate with deslorelin did not differ from that of the controls. Overall, 80% of mares administered eFSH had multiple ovulations compared with 10.3% of the control mares.In experiment 2, the number of large follicles was greater in the eFSH-treated cycle than the previous untreated cycle. In addition, the number of ovulations during the cycle in which mares were treated with eFSH was greater (3.6) than for the control cycle (1.0). The average number of embryos recovered per mare for the eFSH cycle (1.9 ± 0.3) was greater than the embryo recovery rate for the control cycle (0.5 ± 0.3).In summary, the highest ovulation and the highest pregnancy and embryo recovery rates were obtained after administration of 12 mg of eFSH twice daily followed by 2500 IU of hCG. Superovulation with eFSH increased pregnancy rate and embryo recovery rate and, thus, the efficiency of the embryo transfer program.