全文获取类型
收费全文 | 2082篇 |
免费 | 98篇 |
国内免费 | 6篇 |
专业分类
林业 | 173篇 |
农学 | 63篇 |
基础科学 | 17篇 |
409篇 | |
综合类 | 115篇 |
农作物 | 175篇 |
水产渔业 | 172篇 |
畜牧兽医 | 745篇 |
园艺 | 74篇 |
植物保护 | 243篇 |
出版年
2023年 | 17篇 |
2022年 | 58篇 |
2021年 | 71篇 |
2020年 | 76篇 |
2019年 | 93篇 |
2018年 | 79篇 |
2017年 | 111篇 |
2016年 | 98篇 |
2015年 | 62篇 |
2014年 | 80篇 |
2013年 | 136篇 |
2012年 | 139篇 |
2011年 | 133篇 |
2010年 | 92篇 |
2009年 | 84篇 |
2008年 | 104篇 |
2007年 | 85篇 |
2006年 | 92篇 |
2005年 | 84篇 |
2004年 | 69篇 |
2003年 | 51篇 |
2002年 | 67篇 |
2001年 | 21篇 |
2000年 | 15篇 |
1999年 | 18篇 |
1998年 | 6篇 |
1997年 | 14篇 |
1995年 | 9篇 |
1994年 | 8篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 13篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1987年 | 11篇 |
1986年 | 7篇 |
1985年 | 15篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1979年 | 6篇 |
1977年 | 8篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1973年 | 9篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1969年 | 4篇 |
1967年 | 4篇 |
排序方式: 共有2186条查询结果,搜索用时 0 毫秒
11.
Jacob F Polzin DJ Osborne CA Neaton JD Kirk CA Allen TA Swanson LL 《Journal of the American Veterinary Medical Association》2005,226(3):393-400
OBJECTIVE: To determine whether urine protein-to-creatinine ratio (UP:C) > or = 1.0 at initial diagnosis of chronic renal failure (CRF) is associated with greater risk of development of uremic crises, death, and progression of renal failure in dogs. DESIGN: Prospective cohort study. ANIMALS: 45 dogs with CRF PROCEDURE: Dogs were prospectively assigned to 2 groups on the basis of initial UP:C < 1.0 or 2 > or = 1.0. The association between magnitude of proteinuria and development of uremic crises and death was determined before and after dogs with initial UP:C > or =1.0 were assigned to 3 subgroups and compared with dogs with initial UP:C < 1.0. Changes in reciprocal serum creatinine concentration were used to estimate decrease in renal function. RESULTS: Initially, dogs had similar clinical characteristics with the exception of systolic blood pressure and UP:C. Relative risks of development of uremic crises and death were approximately 3 times higher in dogs with UP:C > or =1.0, compared with dogs with UP:C < 1.0. Relative risk of adverse outcome was approximately 1.5 times higher for every 1-unit increment in UP:C. The decrease in renal function was of greater magnitude in dogs with UP:C > or =1.0, compared with dogs with UP:C < 1.0. CONCLUSIONS AND CLINICAL RELEVANCE: Initial UP:C > or =1.0 in dogs with CRF was associated with greater risk of development of uremic crises and death, compared with dogs with UP:C < 1.0. Initial determinations of UP:C in dogs with naturally occurring CRF may be of value in refining prognoses. 相似文献
12.
Mohamed T 《The Veterinary record》2010,167(21):819-824
Forty buffaloes with traumatic pericarditis were examined to characterise the ultrasonographic findings in buffaloes with traumatic pericarditis, determine the extent of the lesions and assess the prognosis. The most noticeable clinical presentations were presternal oedema (73 per cent) and jugular and mammary vein distension (88 per cent). Laboratory findings included neutrophilic leucocytosis, elevated total protein concentration, hypoalbuminaemia, hypergammaglobulinaemia and increased concentration of free fatty acids. Ultrasonographically, fluid in the pericardium appeared as either mild or massive anechoic accumulations containing fibrin threads or were imaged as homogenous, echogenic pericardial effusions. Moderate to severe corrugation of the reticular wall was observed. Deposits of fibrinous tissue interspersed with fluid pockets were seen between the reticulum, dorsal ruminal sac and diaphragm. Perireticular and mediastinal abscesses were imaged and appeared as echogenic lines with anechoic, echogenic, homogenous or heterogeneous contents. Additional ultrasonographic findings included hepatomegaly, dilation of the caudal vena cava, hepatic and portal veins, ascites, echogenic pleural effusions and vegetations of the tricuspid, mitral and pulmonary valves. The ultrasonographic findings were confirmed at postmortem examination. 相似文献
13.
现代火鸡业,定位于产量高、品质好、价格低,且要与消费者对禽肉产品的需求相一致,预防火鸡疫病以保障人类健康是现代火鸡业的导向性目标.…… 相似文献
14.
A.R. Elbeltagy Salah Galal A.Z. Abdelsalam F.E. El Keraby M. Blasi Mahasen M. Mohamed 《Livestock Science》2008,114(2-3):341-346
The present study was carried out to investigate genetic diversity in Nile-Delta and Southern-Egypt buffalo populations in comparison with the Italian buffalo utilizing two microsatellite multiplexes. A total of 104 animals classified into three groups were used, 28, 38 and 38 representing the Nile-Delta, Southern-Egypt and Italian buffalo, respectively. The 15 studied microsatellites were CSSM38, CSSM70, CYP21, CSSM42, CSSM60, MAF65, BM0922, CSSM19, INRA006, ETH02, BM1706, BMC1013, CSSM47, INRA026 and CA004. All studied microsatellites showed allelic polymorphism. Number of polymorphic alleles ranged between 4 alleles (CSSM38, CSSM70 and CYP21) and 11 alleles (CA004). Pairwise Chi-square test for Nile Delta and Southern Egypt showed significant differences in allelic distribution at five loci, CSSM70, CSSM38, BM0922, ETH02 and BM1706. Italian buffalo showed the lowest percentage of observed heterozygotes (65%), while the Southern Egypt showed the highest (71%). Both the Italian and the Delta populations deviated significantly (P < 0.05) from HW equilibrium. Italian buffalo is relatively the most inbred population while the Southern-Egypt buffalo is the only outbred population. High level of genetic differentiation (FST estimates) between the Italian group and each of the Delta and Southern-Egypt group (0.083 and 0.076, respectively) was observed while Southern-Egypt group showed a lower level of genetic differentiation with the Delta group (0.014). Italian buffalo had the greatest genetic distance values with the two Egyptian groups (0.25 and 0.23) while much lower values between the Southern-Egypt and the Delta groups (0.06) was observed. Genetic variation between the Italian buffalo and the Egyptian buffalo was detected in 14 (out of 15) microsatellite loci. While a lower level (than that between Egyptian and Italian) of genetic variation between Southern-Egypt and Delta buffalo populations was expressed by 5 loci. It was concluded that the Southern-Egypt buffalo could be considered as distinct population from the Delta buffalo. In addition, Southern-Egypt group, being the only group with non-significant global deviation from HW equilibrium, the most heterozygous, and the only outbred population as well, is expected to respond more favorably to selection. 相似文献
15.
16.
Mohamed A. M. Alsafy 《Veterinary research communications》2013,37(2):163-170
The aim of the present study was to describe the gill morphology of the gilthead sea bream and sea bass fishes that showed the same feeding habits. Our study focused on the gross morphological, scanning and light microscopical features of the gills, where a many differences in the gill arches and gill rakers surface in both species were explained. Our results marked that; there was an interbranchial median elevation appeared in sea bream. The gill arches length and the gaps between decreased medial wards in both species. The gill rakers had similar arrangement and varied number in both species. The first lateral rakers row was the longest one in sea bass. However the gill filaments appeared in double rows. Gill filaments were long at middle and short at extremities of gill arch in both species. Scanning electron microscopy revealed the surfaces of gill arch covered by a mosaic of pavement cells, varied sized pores of chloride cells and many pointed spines on the rakers ventral border in both species. Two types of taste buds marked on the gill arches and rakers in sea bass. Many lamellae appeared on filaments in both species. 相似文献
17.
Dkhil MA Abdel-Maksoud MA Al-Quraishy S Abdel-Baki AA Wunderlich F 《Veterinary parasitology》2012,186(3-4):222-228
Eimeria coecicola causes intestinal coccidiosis in rabbits and, thereby, enormous economic losses in rabbit farms. Here, we investigate the final target site of E. coecicola, the appendix of rabbits, at the level of gene expression. Rabbits, orally infected with E. coecicola, begin to shed parasitic oocysts with their feces on day 5 p.i., and approximately 1.1 million oocysts are maximally shedded on day 7 p.i. At maximal shedding, the appendix has increased in size by about 2-3-folds and reveals increased hemorrhage which is associated with increases in nitrite/nitrate, malondialdehyde and catalase activity and a decrease in glutathione. Agilent 2-color oligo whole rabbit genome microarray, in combination with quantitative real-time PCR, detects 45 and 36 genes whose expression is more than 2-fold up- and down-regulated, respectively, by E. coecicola infection on day 7 p.i. The most dramatic increase by approximately 50-fold reveals the mRNA of the pro- and anti-inflammatory pleiotropic cytokine interleukin 6 (IL-6), whereas the largest decrease by approximately 13-fold is detected for mRNAs encoding for DBP, SULT3A1, CRP and glutathione-S transferase. Also, there are up- and down-regulations in the expression of genes encoding diverse regions of antibodies. Our data suggest that IL-6 plays a central role in the infection of the appendix of rabbits by E. coecicola, presumably involved in both pathological injuries, host defences and healing processes. 相似文献
18.
del Castillo JR Laroute V Pommier P Zémirline C Keïta A Concordet D Toutain PL 《Journal of animal science》2006,84(11):3155-3166
Anorexigenic substances released during infection may hinder the therapeutic efficacy of in-feed antibiotics. Paracetamol (acetaminophen; PARA) inhibits the anorexia of infection and seems to improve the clinical efficacy of doxycycline (DOX) against bacterial respiratory disease in swine herds. In order to verify whether PARA selectively stimulates intake of DOX-medicated feed in diseased pigs, we documented the pharmacokinetics (PK) of DOX when coadministered with PARA and examined the effect of in-feed PARA on the interindividual variability in plasma concentrations after systemic exposure to in-feed DOX in swine herds with respiratory disease. Systemic exposure to DOX was measured with the area under the curve (AUC) of its plasma concentrations over time. First, a rich-sampling PK study of in-feed and i.v. DOX (10 mg/kg of BW) and PARA (30 and 10 mg/kg of BW, respectively) was performed on 5 pigs. The PK profiles of in-feed DOX were used in mathematical simulations to determine 5 optimal sampling times for the farm-based population PK study. A randomized, blind, parallel PK study was performed in 2 herds with bacterial respiratory disease, where liquid feed was fortified with DOX alone (5 mg x kg of BW(-1) x meal(-1)) or combined with PARA (15 mg x kg of BW(-1) x meal(-1)). Medicated meals were given twice, 12 h apart, to group-housed growing pigs (n > 50 pigs x treatment(-1) x herd(-1), totaling 215 pigs). Plasma concentrations of DOX and PARA were measured with HPLC. At variance with our expectations, PARA decreased (P = 0.069) mean AUC of in-feed DOX and did not decrease its variability (P > 0.34). Mean AUC of DOX increased with feed intake and with initial exposure to DOX, and was greater in sick animals. Therefore, symptomatic PARA-induced improvement in bacterial respiratory disease control with DOX is more likely caused by its analgesic/antipyretic effects than by its orexigenic effect. Interindividual variation in the AUC of DOX was large in pigs given group medication, even when sufficient feeding space was allowed and the amount of feed offered was greater than their requirements. Therefore, future studies to improve the efficacy of group antibiotic therapy should focus on feeding behavior characteristics as well as biopharmaceutical properties of medicated feeds. 相似文献
19.
薛俊梅 《国外畜牧学(猪与禽)》2010,30(5)
多种肠道紊乱会威胁家禽的健康,并引起发病和死亡,造成经济损失.抗生素生长促进剂的禁用,使肠道细菌受到诱发因素的影响后而使肠道内腔遭到破坏,提高了本病的发生率.你如何认识这一问题并会采取什么措施呢? 相似文献
20.