全文获取类型
收费全文 | 5363篇 |
免费 | 317篇 |
国内免费 | 4篇 |
专业分类
林业 | 271篇 |
农学 | 244篇 |
基础科学 | 9篇 |
1002篇 | |
综合类 | 615篇 |
农作物 | 587篇 |
水产渔业 | 425篇 |
畜牧兽医 | 2126篇 |
园艺 | 74篇 |
植物保护 | 331篇 |
出版年
2023年 | 29篇 |
2022年 | 89篇 |
2021年 | 116篇 |
2020年 | 97篇 |
2019年 | 108篇 |
2018年 | 141篇 |
2017年 | 164篇 |
2016年 | 185篇 |
2015年 | 165篇 |
2014年 | 202篇 |
2013年 | 293篇 |
2012年 | 351篇 |
2011年 | 419篇 |
2010年 | 227篇 |
2009年 | 222篇 |
2008年 | 316篇 |
2007年 | 302篇 |
2006年 | 270篇 |
2005年 | 249篇 |
2004年 | 232篇 |
2003年 | 189篇 |
2002年 | 203篇 |
2001年 | 145篇 |
2000年 | 120篇 |
1999年 | 80篇 |
1998年 | 36篇 |
1997年 | 21篇 |
1996年 | 22篇 |
1995年 | 22篇 |
1994年 | 16篇 |
1993年 | 23篇 |
1992年 | 33篇 |
1991年 | 27篇 |
1990年 | 35篇 |
1989年 | 40篇 |
1988年 | 33篇 |
1987年 | 40篇 |
1986年 | 18篇 |
1985年 | 32篇 |
1984年 | 23篇 |
1983年 | 27篇 |
1981年 | 19篇 |
1980年 | 15篇 |
1978年 | 21篇 |
1977年 | 19篇 |
1976年 | 28篇 |
1974年 | 20篇 |
1973年 | 22篇 |
1972年 | 22篇 |
1971年 | 15篇 |
排序方式: 共有5684条查询结果,搜索用时 15 毫秒
991.
Paull DR Small AH Lee C Palladin P Colditz IG 《Veterinary anaesthesia and analgesia》2012,39(5):539-549
Objective To evaluate the analgesic efficacy of the NSAIDs flunixin and meloxicam administered locally to the scrotum before ring castration. Study design Randomised, controlled, prospective study. Animals Forty eight single born male Merino lambs. Methods Lambs, aged approximately 4 weeks, were allocated to four groups for castration. Groups were: sham control; castration + saline; castration + flunixin; castration + meloxicam. Drugs (5 mL) were administered subcutaneously around the circumference of the scrotum immediately before castration. Cortisol, rectal temperature, haematology and plasma haptoglobin were measured before and up to 48 hours after treatment. Behaviour recorded by video for 12 hours after treatment was classified as pain avoidance behaviours in the first hour and postural behaviours in three 4 hour intervals. Results Ring castration (saline group) induced a bi‐phasic increase in cortisol with peaks at 90 minutes and 24 hours but no significant changes in haematology, haptoglobin or rectal temperature. Pain avoidance behaviours were increased and teat seeking decreased. Normal lying and normal standing postures were decreased and abnormal ventral lying, statue standing, abnormal standing and total abnormal postures increased. Flunixin decreased cortisol at 90 minutes (60.3 versus 117.3 nmol L?1) and cortisol AUC (0–6 hours), decreased elevated leg movement (2.5 versus 5.4 events) and sum of pain avoidance behaviours (8.5 versus 16.7 events), improved time spent in normal ventral lying and decreased abnormal ventral lying and total abnormal postures compared to saline treated lambs. In a similar contrast, meloxicam caused non‐significant decreases in cortisol at 90 minutes, cortisol AUC (0–6 hours) and pain avoidance behaviours, and significantly improved the postural behaviours normal ventral lying (26.7 versus 15.4%) and normal standing (13.9 versus 7.5%), and reduced abnormal standing and total abnormal postures. Physiological and behavioural responses associated with ring castration for both NSAID treatment groups were generally greater than sham controls. Conclusions and clinical relevance Locally administered NSAIDs provided partial analgesia for ring castration. 相似文献
992.
Heechul Kim Taeki Lee Jeeyoung Lee Meejung Ahn Changjong Moon Myung Bok Wie Taekyun Shin 《Journal of veterinary science (Suw?n-si, Korea)》2006,7(2):101-104
The expression of caveolin-1 and -2 in the retina was examined; Western blot analysis showed that both were present. Immunohistochemistry indicated that caveolin-1 was expressed in the majority of retinal layers, including the ganglion cell layer, inner plexiform layer, outer plexiform layer, and in the vascular endothelial cells of the retina. Caveolin-2 was primarily immunostained in the vessels, but in a few other elements as well. This is the first demonstration of caveolin differential expression in the retina of rats, and suggests that caveolin plays an important role in signal transduction in glial cells and neuronal cells. 相似文献
993.
The purpose of this study was to compare carbon sequestration between moso bamboo (Phyllostachys heterocycla) and China fir (Cunninghamia lanceolata) forests. The study site was located in the lower mountain area of central Taiwan, where both moso bamboo and China fir were rich. In addition, moso bamboo and China fir forests were surveyed on 12 and 19 plantations, respectively. We predicted carbon sequestration based on the allometric model for moso bamboo and China fir forests and compared the relationships between characteristics of bamboo forests and elevation. The results showed that mean diameter at breast height (DBH), culms per hectare and aboveground biomass were not clearly affected by elevation, whereas a negative correlation (R = −0.600, p = 0.039) between mean DBH and stand density was found for moso bamboo forests. Moreover, the aboveground carbon storage was higher for China fir forests than for moso bamboo (99.5 vs. 40.6 Mg ha−1). However, moso bamboo is an uneven-aged stand which is only composed of 1-5-year-old culms, while China fir is an even-aged stand and the age range is from 15 to 54 years, such that, per year, the mean aboveground carbon sequestration is 8.13 ± 2.15 and 3.35 ± 2.02 Mg ha−1 for moso bamboo and China fir, respectively. On the other hand, the mean carbon sequestration of China fir decreases with increasing the age class. Furthermore, the ratio of moso bamboo to China fir is 2.39 and a T-test showed that the aboveground carbon levels were significantly different between these two species; thus, moso bamboo is a species with high potential for carbon sequestration. 相似文献
994.
Hwa Yeun Nam Brad Coates Kyung Seok Kim Marana Park Joon-Ho Lee 《Journal of insect science (Online)》2015,15(1)
The white-backed planthopper, Sogatella furcifera (Horváth) (Hemiptera: Delphacidae), is a major pest of rice and has long-range migratory behavior in Asia. Microsatellite markers (simple sequence repeats) have been widely used to determine the origins and genetic diversity of insect pests. We identified novel microsatellite loci for S. furcifera samples collected from Laos, Vietnam, and three localities in Bangladesh from next-generation Roche 454 pyrosequencing data. Size polymorphism at 12 microsatellite loci was verified for 40 adult individuals collected from Shinan, South Korea. The average number of alleles per locus was 7.92. The mean values of observed (Ho) and expected heterozygosities (HE) were 0.615 and 0.757, respectively. These new microsatellite markers will be a resource for future ecological genetic studies of S. furcifera samples across more broad geographic regions in Asia and may assist in estimations of genetic differentiation and gene flow among populations for implementation of more effective management strategies to control this serious rice pest. 相似文献
995.
996.
Yongsun Kim Seung Hoon Lee Wan Hee Kim Oh-Kyeong Kweon 《Journal of veterinary science (Suw?n-si, Korea)》2016,17(1):123-126
Thirty-four dogs with no deep pain perception due to acute thoracolumbar intervertebral disc disease underwent decompression surgery within 1 week of diagnosis. All dogs underwent hemilaminectomy. Adipose derived mesenchymal stem cells (AD-MSCs) were transplanted into the injured spinal cord parenchyma for the AD-MSCs transplant dogs. Long-term outcome was evaluated at the end of the follow-up period (> 6 months). AD-MSCs combination treatment showed better recovery outcomes compared to decompression surgery alone. These results indicate that this stem cell therapy is a potential therapeutic strategy to overcome the limitations of treatment for spinal cord injury in clinical medicine. 相似文献
997.
Y. H. Lee 《Euphytica》1991,54(3):251-254
Summary Ten Aranda cultivars commercially grown in Singapore were selected to study their genomic constitutions and flower characteristics. Cytological evidence and breeding records of these cultivars showed that they are of three genomic classes. Four of them are diploid with AV genomes (one Arachnis and one Vanda genome), another four are triploid with AVV genomes and the remaining two are tetraploid with AVVV genomes. Sizes of flowers as well as of sepals and petals generally show significant increases from diploid to tetraploid. This trend reflects the increasing influence of Vanda resulting from additional one and two Vanda genomes in triploid and tetraploid respectively as compared to diploid cultivars. Among the three genomic classes, diploid cultivars generally bear less flowers per spray than those of triploid and tetraploid although exceptions may occur. There is no clear trend in the length of inflorescences although diploid cultivars tend to have less compact spray with flowers more distantly spaced out. 相似文献
998.
999.
Hye Kwon Kim Jeong Sun Yang Hyoung Joon Moon Seong Jun Park Yuzi Luo Chul Seung Lee Dae Sub Song Bo Kyu Kang Soo Kyung Ann Chan Hyuk Jun Bong Kyun Park 《Journal of veterinary science (Suw?n-si, Korea)》2009,10(2):121-130
The 23 open reading frame (ORF) 5 sequences of Korean type II porcine reproductive and respiratory syndrome virus (PRRSV) were collected from viremic sera from the (modified live vaccine) MLV-vaccinating and non-vaccinating farms from 2007 to 2008. The samples were phylogenetically analyzed with previous ORF5 sequences, including type I Korean PRRSV, and previously reported or collected sequences from 1997 to 2008. A MN184-like subgroup of type II Korean PRRSV was newly identified in the viremic sera collected from 2007 to 2008. And of the type I PRRSVs, one subgroup had 87.2~88.9% similarity with the Lelystad virus, showing a close relationship with the 27~2003 strain of Spain. The maximum parsimony tree of type II PRRSV from 1997 to 2008 showed that they had evolved to four lineages, subgroups 1, 2, 3 and 4. Most of the recently collected type II PRRSVs belonged to subgroup 4 (48%). The region of three B-cell epitopes and two T-cell epitopes of ORF5 amino acids sequences was considerably different from the MLV in subgroups 3 and 4. In conclusion, the existence of type I PRRSV, which was genetically different from Lelystad virus (Prototype of type I PRRSV), and heterologous type II PRRSVs of viremic pigs detected even in the MLV-vaccinating farms indicated the need for new vaccine approaches for the control of PRRSV in Korea. 相似文献
1000.
Penicillinolide A: A New Anti-Inflammatory Metabolite from the Marine Fungus Penicillium sp. SF-5292
Dong-Sung Lee Wonmin Ko Tran Hong Quang Kyoung-Su Kim Jae Hak Sohn Jae-Hyuk Jang Jong Seog Ahn Youn-Chul Kim Hyuncheol Oh 《Marine drugs》2013,11(11):4510-4526
In the course of studies on bioactive metabolites from marine fungi, a new 10-membered lactone, named penicillinolide A (1) was isolated from the organic extract of Penicillium sp. SF-5292 as a potential anti-inflammatory compound. The structure of penicillinolide A (1) was mainly determined by analysis of NMR and MS data and Mosher’s method. Penicillinolide A (1) inhibited the production of NO and PGE2 due to inhibition of the expression of iNOS and COX-2. Penicillinolide A (1) also reduced TNF-α, IL-1β and IL-6 production, and these anti-inflammatory effects were shown to be correlated with the suppression of the phosphorylation and degradation of IκB-α, NF-κB nuclear translocation, and NF-κB DNA binding activity. In addition, using inhibitor tin protoporphyrin (SnPP), a competitive inhibitor of HO activity, it was verified that the inhibitory effects of compound 1 on the production of pro-inflammatory mediators and NF-κB DNA binding activity were partially associated with HO-1 expression through Nrf2 nuclear translocation. 相似文献