全文获取类型
收费全文 | 917篇 |
免费 | 92篇 |
专业分类
林业 | 45篇 |
农学 | 12篇 |
基础科学 | 3篇 |
99篇 | |
综合类 | 28篇 |
农作物 | 32篇 |
水产渔业 | 25篇 |
畜牧兽医 | 684篇 |
园艺 | 16篇 |
植物保护 | 65篇 |
出版年
2023年 | 15篇 |
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 39篇 |
2019年 | 14篇 |
2018年 | 28篇 |
2017年 | 30篇 |
2016年 | 29篇 |
2015年 | 35篇 |
2014年 | 52篇 |
2013年 | 57篇 |
2012年 | 63篇 |
2011年 | 75篇 |
2010年 | 53篇 |
2009年 | 84篇 |
2008年 | 58篇 |
2007年 | 48篇 |
2006年 | 38篇 |
2005年 | 34篇 |
2004年 | 44篇 |
2003年 | 30篇 |
2002年 | 26篇 |
2001年 | 23篇 |
2000年 | 11篇 |
1999年 | 11篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1984年 | 5篇 |
1982年 | 4篇 |
1978年 | 2篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1966年 | 2篇 |
1965年 | 1篇 |
1961年 | 1篇 |
1960年 | 2篇 |
1959年 | 1篇 |
1958年 | 4篇 |
1957年 | 2篇 |
排序方式: 共有1009条查询结果,搜索用时 546 毫秒
101.
The pre-emptive effect of epidural ketamine on wound sensitivity in horses tested by using von Frey filaments 总被引:1,自引:0,他引:1
Márcia A Rédua DVM MSc Carlos AA Valadão DVM DSc Juan C Duque DVM MSc Lúcia T Balestrero DVM MSc 《Veterinary anaesthesia and analgesia》2002,29(4):200-206
Objective To evaluate the pre‐emptive analgesic effect of pre‐incisional epidural ketamine. Study Design A blinded, randomized experimental study. Animals Sixteen mixed breed mares, 7.6 ± 2.8 years old, weighing 352 ± 32 kg. Methods In a pilot study, an incision was made on one lateral thigh using a lidocaine block and no further analgesics, and it was verified that the nociceptive threshold was lower on the incised side than nonincised side (p ≤ 0.05), and that von Frey filaments evoked a pain response. The 16 animals were divided into group A (ketamine, n = 9) and B (saline, n = 7). An epidural catheter was inserted 24 hours before the trials. The thigh was shaved bilaterally, and the right side was blocked (incised side) using lidocaine. Twenty‐five minutes later, ketamine (A) or saline (B) was administered epidurally. Five minutes later, a 10‐cm skin incision was made on the right side, and then sutured. Nociceptive threshold was determined with von Frey filaments at 1, 3, and 5 cm around the incision at 15‐minute intervals for 2 hours, then at 4, 6, and 8 hours. Behavioral alterations, heart and respiratory rates were recorded. Nociceptive thresholds from these points were averaged to obtain mean values at each time, converted to a logarithmic scale, and submitted to a nonparametric analysis (Mann–Whitney and one‐way repeated measures anova test, p ≤ 0.05). Results After 8 hours, the global range score revealed reduced hyperalgesia (p < 0.01) around the incision in 92% (4.65–4.27) of evaluated intervals in group A (ketamine). There were no significant changes in behavior, heart and respiratory rates. Conclusions It was concluded that pre‐emptive epidural ketamine reduced post‐incisional pain in the horse, and that von Frey filaments were able to quantify cutaneous sensitivity after tissue damage. Clinical relevance Epidural ketamine injection can reduce post‐incisional sensitivity in the horse. 相似文献
102.
P Hedenqvist DVM Jv Roughan BSc PhD He Orr BVM&S Cert LAS L M Antunes MSc DVM 《Veterinary anaesthesia and analgesia》2001,28(1):18-25
Objective To compare the characteristics of anaesthesia induced with four dose combinations of ketamine/medetomidine. Design Prospective randomized study. Animals Five female New Zealand White (NZW) rabbits of approximately 2.3 kg. Methods Rabbits were given one of four drug combinations (25/0.25; 15/0.5; 15/0.25 and 10/0.5 mg kg?1 IM) on four successive occasions with a four day interval. Response to injection and then arterial blood gas and cardiovascular parameters were recorded at predetermined time points. Toe and ear pinch reflexes gave measures of total duration of surgical anaesthesia and total sleep time. Analyses used repeated measures analysis of variance. Results Induction was smooth with little reaction to injection and intubation achieved easily. Two combinations (15/0.25, 10/0.5) produced moderate hypoxaemia (mean pO2 < 8.0 kPa) and two (25/0.25, 15/0.5) very marked hypoxaemia (mean pO2 < 5.3 kPa). This was reversed within 15 minutes of oxygen administration and all rabbits recovered uneventfully. Heart rates fell in all cases, with only minimal effects on arterial blood pressure and no cardiac arrhythmias. Mean duration of surgical anaesthesia was significantly longer for dose groups 25/0.25 (57 ± 12 minutes) and 15/0.5 (59 ± 17 minutes, p = 0.01) compared to dose group 15/0.25 (27 ± 8 minutes). Only three animals in the 10/0.5 mg kg?1 group achieved surgical anaesthesia. Mean duration of loss of the ear pinch reflex was similar between doses, being, respectively, 64 ± 13, 81 ± 7, 60 ± 22 and 62 ± 24 minutes. Sleep time was significantly longer for the 15/0.5 dose (112 ± 10 minutes) compared to 15/0.25 (86 ± 22 minutes, p = 0.04). Sleep times for the 25/0.25 and 10/0.5 mg kg?1 doses were, respectively, 103 ± 23 and 108 ± 12 minutes. Conclusions Ketamine/medetomidine reliably produces smooth induction and recovery in the NZW rabbit, but due to the degree of hypoxaemia produced, should only be used with simultaneous provision of oxygen. Clinical relevance Currently recommended dose rates of ketamine/medetomidine for minor procedures such as ovariohysterectomy in rabbits (25 mg/0.5 mg kg?1) are unnecessarily high; a dose of 15/0.25 mg kg?1 should be adequate for 15–30 minutes of surgical anaesthesia. 相似文献
103.
Improved water repellency of black spruce wood surfaces after treatment in carbon tetrafluoride plasmas 总被引:1,自引:0,他引:1
Bouddah Poaty Bernard Riedl Pierre Blanchet Vincent Blanchard Luc Stafford 《Wood Science and Technology》2013,47(2):411-422
Plasma treatments for black spruce wood (Picea mariana (Mill.) B.S.P.), a widespread forest species from Canada, were carried out in order to waterproof the exposed surfaces. Experiments were performed using inductively coupled argon plasma with carbon tetrafluoride as the gaseous precursor for plasma-enhanced chemical vapor deposition of functional fluoropolymer coatings on wood. Analysis of the wettability through water contact angle measurements showed water-repellent characteristics, with static contact angles up to 130° depending on plasma exposure time, CF4 concentration in the Ar/CF4 plasma, and plasma source-to-substrate distance. X-ray photoelectron spectroscopy investigations of plasma-treated wood surfaces confirmed the growth of a thin, fluorocarbon layer with fluorine atomic concentrations close to 50 % on highly hydrophobic wood surfaces. Estimation of the thickness of the coatings by stylus profilometry revealed that a minimum layer thickness of about 80 nm is required to obtain water repellant wood surfaces with minimum water uptake. This complete set of data indicates that fluorocarbon-containing plasmas represent a very promising approach for improving the durability of wood products in wet and humid conditions. 相似文献
104.
105.
106.
Distal limb wounds are frequent in horses after traumatic events. The use of platelet-rich plasma (PRP) represents a simple method of treating wounds in equines. A case of a chronic severely contaminated distal limb wound in an 8-month-old foal is presented. The patient was managed with the combination of standard wound therapy (debridement and bandages), surgery, and PRP obtained by a manual tube protocol. No complications were observed with the PRP treatment, and the foal was fully recovered 2 months later. The results from this case report indicate that PRP and its by-products (platelet-poor plasma) could be used as an adjunctive treatment in severe distal limb wounds in horses. A clinical controlled study should be performed to test this hypothesis. 相似文献
107.
108.
109.
Abigail L. Fowden Juanita K. JellymanOrlando A. Valenzuela DVM MSc Alison J. Forhead PhD 《Journal of Equine Veterinary Science》2013
Human epidemiological observations and studies of experimental animals have shown that low birth weight is associated with adult phenotypes characterized by abnormalities in cardiovascular, metabolic, and endocrine function. In human populations, these changes can lead to overt degenerative diseases such as hypertension and type 2 diabetes. Because fetal growth depends primarily on the nutrient supply, the associations between birth weight and adult phenotype have been linked to poor nutrition in utero. The fetal supply of nutrients and oxygen depends on both the availability of these substances in the mother and the functional capacity of the placenta to supply them to the fetus. This review takes a comparative approach to examining the nutritional programming of adult physiological phenotype in mammals with emphasis on the horse where possible. It considers the role of maternal nutritional state and placental function in these processes and discusses the cellular and molecular mechanisms operating in utero that are responsible for the epigenetic regulation of phenotypical diversity. 相似文献
110.
Priscilla N. Guasti Gabriel A. MonteiroRosiara R. Maziero MSc Ian MartinBruno R. Avanzi MSc José A. Dellaqua Jr.Frederico O. Papa PhD 《Journal of Equine Veterinary Science》2013
This study evaluated whether pentoxifylline (PTX) present in the flushing extender influenced the function of equine epididymal spermatozoa after recovery and after thawing. For this experiment, 58 testicles from 29 Brazilian Jumping Horses were used. Cauda epididymides of each stallion were separated and flushed with a skim milk extender, with or without 7.18 mM PTX and then subjected to the freezing process. Samples flushed with the extender containing PTX showed a significant increase in total motility, progressive motility, straight line velocity, curvilinear velocity, and percentage of rapid sperm immediately after the recovery of epididymal sperm and after 15 minutes of incubation at 37°C (P < .05). However, the presence of PTX in the flushing extender did not affect the post-thaw motility parameters or plasma membrane integrity (P > .05). The results of this study showed that the PTX present in the flushing extender improved motility parameters of recently recovered epididymal sperm and had no deleterious effects on plasma membrane integrity and freezability of equine epididymal sperm. 相似文献