全文获取类型
收费全文 | 19227篇 |
免费 | 184篇 |
国内免费 | 4篇 |
专业分类
林业 | 3794篇 |
农学 | 1359篇 |
基础科学 | 157篇 |
3199篇 | |
综合类 | 1405篇 |
农作物 | 2151篇 |
水产渔业 | 2013篇 |
畜牧兽医 | 2090篇 |
园艺 | 1173篇 |
植物保护 | 2074篇 |
出版年
2024年 | 8篇 |
2023年 | 21篇 |
2022年 | 31篇 |
2021年 | 71篇 |
2020年 | 78篇 |
2019年 | 91篇 |
2018年 | 2801篇 |
2017年 | 2759篇 |
2016年 | 1255篇 |
2015年 | 132篇 |
2014年 | 94篇 |
2013年 | 113篇 |
2012年 | 972篇 |
2011年 | 2339篇 |
2010年 | 2233篇 |
2009年 | 1343篇 |
2008年 | 1526篇 |
2007年 | 1785篇 |
2006年 | 228篇 |
2005年 | 287篇 |
2004年 | 294篇 |
2003年 | 334篇 |
2002年 | 236篇 |
2001年 | 38篇 |
2000年 | 64篇 |
1999年 | 28篇 |
1998年 | 16篇 |
1997年 | 7篇 |
1996年 | 18篇 |
1995年 | 15篇 |
1994年 | 12篇 |
1993年 | 21篇 |
1992年 | 11篇 |
1991年 | 15篇 |
1990年 | 7篇 |
1989年 | 16篇 |
1988年 | 17篇 |
1987年 | 11篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1974年 | 8篇 |
1973年 | 3篇 |
1970年 | 3篇 |
1968年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
Lesley A. Hawson Andrew N. McLean Paul D. McGreevy 《Journal of Veterinary Behavior: Clinical Applications and Research》2013,8(2):74-81
Horse riders have used layers between saddles and their horse's back since ancient times. Despite the apparent common usage of such layers, most research regarding pressures under horses' saddles seems to have been conducted without such layers present. An online survey of equestrian riders was conducted to quantify the use of such layers and how the layers behaved during use. This produced 1,011 responses from participants in 16 equestrian activities. More than 98% of respondents reported they used some form of layer between their horse's back and the saddle. Differences in layer usage were associated with the respondent's preferred riding discipline and the wither type of their horse. Compensation for perceived saddle fit problems was commonly cited as a reason for using layers. Although horse comfort was nominated by 87.5% of respondents as a reason for using a layer between saddle and the horse's back, many respondents (45%) reported using more than 1 layer. This often resulted in layers thicker than 1 cm, which paradoxically could compromise horse welfare. Half of the respondents reported that the layer between the saddle and the horse's back slipped during riding. Although some significant risk factors for this slippage were identified, they are deemed not to be definitive because of similar factors being identified by the group who did not report layer slippage. These results suggest that incorrect usage of layer between saddles and horses' backs can sabotage good saddle design and compromise equine welfare. Future research on the layers used between the saddles and horses' back is warranted. The question of whether using thicker layers can create greater pressure under saddles or improve rider–horse communication also needs to be investigated. 相似文献
75.
Background
Identification of Staphylococci to species level in veterinary microbiology is important to inform therapeutic intervention and management. We report on the efficacy of three routinely used commercial phenotypic methods for staphylococcal species identification, namely API Staph 32 (bioMérieux), RapID (Remel) and Staph-Zym (Rosco Diagnostica) compared to genotyping as a reference method to identify 52 staphylococcal clinical isolates (23 coagulase positive; 29 coagulase negative) from companion animals in Irish veterinary hospitals.Results
Genotyping of a 412 bp fragment of the staphylococcal tuf gene and coagulase testing were carried out on all 52 veterinary samples along with 7 reference strains. In addition, genotyping of the staphylococcal rpoB gene, as well as PCR-RFLP of the pta gene, were performed to definitively identify members of the Staphylococcus intermedius group (SIG). The API Staph 32 correctly identified all S. aureus isolates (11/11), 83% (10/12) of the SIG species, and 66% (19/29) of the coagulase negative species. RapID and Staph-Zym correctly identified 61% (14/23) and 0% (0/23) respectively of the coagulase-positives, and 10% (3/29) and 3% (1/29) respectively of the coagulase-negative species.Conclusions
Commercially available phenotypic species identification tests are inadequate for the correct identification of both coagulase negative and coagulase positive staphylococcal species from companion animals. Genotyping using the tuf gene sequence is superior to phenotyping for identification of staphylococcal species of animal origin. However, use of PCR-RFLP of pta gene or rpoB sequencing is recommended as a confirmatory method for discriminating between SIG isolates. 相似文献76.
77.
Baker SJ Johnson PJ David A Cook CR 《Journal of the American Veterinary Medical Association》2004,224(12):1967-70, 1931
Chronic gastroesophageal reflux disease was diagnosed in a 22-year-old female Tennessee Walking Horse that had signs of bruxism and ptyalism. Esophageal ulceration was detected via endoscopy. Compared with the damage to the proximal portions of the esophagus, the severity of the ulceration increased toward the gastroesophageal junction. Esophageal ulceration attributable to chronic gastric acid reflux is usually secondary to pyloric outflow obstruction in horses. In the horse of this report, there was no evidence of either a chronic pyloric or duodenal obstruction that could have resulted in esophageal ulceration. Esophageal ulceration in this horse was attributed to gastroesophageal reflux disease, a common condition in humans in which the underlying abnormality is functional incompetence of the gastroesophageal junction. Treatment is directed at decreasing gastric acidity and protecting the ulcerated mucosa. In the horse of this report, treatment was unsuccessful and the horse was euthanatized; a physical cause of gastroesophageal reflux disease was not identified during an extensive postmortem examination. 相似文献
78.
Sparkes AH Mardell EJ Deaton C Kirschvink N Marlin D 《Journal of Feline Medicine and Surgery》2004,6(5):335-338
Exhaled breath condensate has been collected in other species and used as a non-invasive method of evaluating airway disease by measurement of various markers in the fluid, including hydrogen peroxide, nitric oxide, leukotrienes and prostaglandins. We describe a novel technique for the collection of exhaled breath condensate from cats, which enabled collection of fluid and measurement of its hydrogen peroxide concentration. Further studies will be needed to establish the value of this technique in the investigation of feline respiratory disease. 相似文献
79.
80.
Mukesh Bhakat Tushar K. Mohanty Ashok K. Gupta Virendra S. Raina Biswajit Brahma R. K. Mahapatra M. Sarkar 《Tropical animal health and production》2010,42(7):1363-1366
Effect of Foot and Mouth disease (FMD) vaccination was studied on semen quality parameters of 19 Karan Fries (KF) and eight
Murrah (MU) breeding bulls during the period 2002 to 2004 at Artificial Breeding Complex, NDRI, Karnal. A total of non-vaccinated
155 KF and 72 MU bulls' ejaculates were taken as control, while 169 KF and 51 MU bulls' ejaculates, collected after vaccination,
were used to study the effect of vaccination stress. The results showed that FMD vaccination had no significant (P > 0.05) effect on ejaculate volume and total volume per day of semen in both KF and MU bulls. Volume of semen increased slightly
during post-vaccination period in both the breeds. After FMD vaccination, there was significant (P < 0.01) decrease in mass activity (2.27 ± 0.06 vs. 1.67 ± 0.07 and 2.49 ± 0.09. vs. 1.75 ± 0.10, for KF and MU, respectively),
initial motility (56.89 ± 0.03% vs. 44.62 ± 0.02% and 62.26 ± 0.04% vs. 47.08 ± 0.05%, for KF and MU, respectively), sperm
concentration (754.19 ± 23.96 vs. 554.14 ± 22.95 × 106/ml and 848.61 ± 33.65 vs. 571.57 ± 39.99 × 106/ml, for KF and MU, respectively), and total sperm output per ejaculate (3,685.94 ± 158.40 vs. 2,781.54 ± 151.70 × 106 and 2,218.75 ± 133.14 vs. 1,582.84 ± 158.20 × 106, for KF and MU, respectively). Application of FMD vaccine had significantly (P < 0.05) adverse effect on most of the seminal attributes during post-vaccination in KF and MU buffalo bulls. So, the spermiograms
affected following vaccination suggest that in bovines, the semen collection and preservation should be suspended till normal
fertility of sperm is restored to avoid the failure of conception from artificial insemination using such semen. 相似文献