全文获取类型
收费全文 | 5613篇 |
免费 | 449篇 |
国内免费 | 109篇 |
专业分类
林业 | 613篇 |
农学 | 283篇 |
基础科学 | 64篇 |
1518篇 | |
综合类 | 293篇 |
农作物 | 364篇 |
水产渔业 | 712篇 |
畜牧兽医 | 1621篇 |
园艺 | 128篇 |
植物保护 | 575篇 |
出版年
2024年 | 8篇 |
2023年 | 44篇 |
2022年 | 76篇 |
2021年 | 153篇 |
2020年 | 184篇 |
2019年 | 217篇 |
2018年 | 270篇 |
2017年 | 283篇 |
2016年 | 296篇 |
2015年 | 227篇 |
2014年 | 270篇 |
2013年 | 412篇 |
2012年 | 488篇 |
2011年 | 482篇 |
2010年 | 324篇 |
2009年 | 278篇 |
2008年 | 276篇 |
2007年 | 288篇 |
2006年 | 237篇 |
2005年 | 244篇 |
2004年 | 198篇 |
2003年 | 194篇 |
2002年 | 149篇 |
2001年 | 93篇 |
2000年 | 89篇 |
1999年 | 71篇 |
1998年 | 42篇 |
1997年 | 37篇 |
1996年 | 24篇 |
1995年 | 23篇 |
1994年 | 14篇 |
1993年 | 7篇 |
1992年 | 12篇 |
1991年 | 11篇 |
1990年 | 14篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1976年 | 5篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1969年 | 4篇 |
1918年 | 5篇 |
排序方式: 共有6171条查询结果,搜索用时 562 毫秒
991.
Felisbina L. Queiroga Dolores Prez-Alenza Gema Silvan Laura Pea Carlos S. Lopes Juan C. Illera 《Research in veterinary science》2010,89(3):396-403
The biological implication of the growth hormone/insulin like growth factor-I (GH/IGF-I) axis in canine mammary tumours (CMT) has been recently demonstrated, however its clinical and prognostic implications are unknown. Our aim was to investigate its prognostic significance.Hormonal determinations were done by enzyme immunoassays techniques validated for canine species in serum and tumour tissue from 32 bitches with CMT and in serum and normal mammary tissue from 10 controls. Serum and tissular GH and IGF-I concentrations were significantly higher in the case of malignant tumour compared with benign and controls. GH and IGF-I elevated concentrations were significantly associated with tumour relapse and/or metastases during follow-up and in dogs with reduced survival times; however these parameters were not independent prognostic factors in multivariate analysis. This association demonstrates a link between high serum and intratumoural GH and IGF-I concentrations and a worse prognosis and opens the possibility to new anticancer endocrine therapies in dogs. 相似文献
992.
993.
R. García‐Valverde R. Nieto J. F. Aguilera 《Journal of animal physiology and animal nutrition》2010,94(5):e203-e214
We conducted two experiments with heavy Iberian pigs to determine the ileal digestibility of amino acids (AA) in acorns and freshly cut herbage, and the effects of adding fresh herbage upon the supply of ileal digestible AA when pigs were fed on holm‐oak acorns. In Experiment 1, carried out in cannulated pigs of 107 kg bodyweight (BW), daily intake of acorns reached 44.9 g DM/kg0.75 BW. Arg, His and Thr showed the lowest apparent ileal digestibility (AID) values, whereas Met, the branched‐chain AA and Phe had the highest coefficients. The AID of total EAA was 0.716 but only 0.222 for NEAA. Most of the digestive and absorptive processes of acorn protein occurred before the hindgut. Acorn provides (per kg DM) 2.27 g apparent ileal digestible Lys and 22.7 g apparent total digestible AA. Standardized ileal digestibility (SID) values for EAA, NEAA and total AA were 0.924 ± 0.020, 0.784 ± 0.041 and 0.860 ± 0.029. In Experiment 2 fresh herbage was given to six cannulated Iberian pigs of 140 kg either as a single feed (13.7 g DM/kg0.75 BW) or as a supplement to acorns (28.4 g DM/kg0.75 BW). When only freshly cut forage was offered the AID of the EAA, NEAA and total AA was close to 0.65 and supplied (per kg DM ingested) 5.61 g AID Lys and 91.7 g digestible AA. Standardized ileal values were 0.744 ± 0.023, 0.912 ± 0.038 and 0.831 ± 0.030 respectively. The addition of fresh forage to the acorns led to a significant decrease in AID of AA in acorn due to digesta transfer to the hindgut: His (p < 0.01), Met (p < 0.001), Phe (p = 0.092), Thr (p < 0.05) and Val (p < 0.05), but Arg, Lys and the branched‐chain AA remained unaffected. The main contribution of herbage to AA nutrition of the grazing Iberian pig relies mainly on increasing the supply of digestible AA for pig tissues. 相似文献
994.
Gustavo A. Abuja LV José M. García‐López VMD Diplomate ACVS Richard Doran DVM MS Diplomate ACVS 《Veterinary surgery : VS》2010,39(5):654-659
Objective: To report outcome of horses after standing pararectal cystotomy for removal of uroliths. Study Design: Case series. Animals: Horses (n=9) with cystic calculi. Methods: Medical records (December 1998–May 2007) of horses with cystic calculi that had standing pararectal cystotomy were reviewed. Signalment; urolith number, size, and type; surgical technique; sedation and analgesia protocols; intra‐ and postoperative complications and outcome were analyzed. Results: Uroliths (mean diameter, 6.37 cm; median, 6 cm; range, 3–10 cm) were removed intact without need for fragmentation. Eight (89%) horses had no complications and 1 horse (11%) developed persistent drainage from the perineal incision and incisional healing was prolonged. The complications resolved after wound revision, and although cystoscopy showed absence of uroliths, the clinical signs associated with cystitis recurred. Conclusions: Cystic calculi can be removed safely in standing horses using a pararectal approach. The procedure was well tolerated and no serious complications were encountered. Clinical Relevance: Pararectal cystotomy allows removal of cystic calculi in standing sedated horses. The technique may offer an economic advantage over approaches that require general anesthesia. 相似文献
995.
Arno Lindner Raul Signorini Jorge Vassallo Fabiana Tomatis Francis M. Flores María E. Gagliano Jimena Curiotti Evelina Terragona 《Journal of Equine Veterinary Science》2010
This study examined the reproducibility and repeatability of muscle thickness (MT) measurements with ultrasound for the following muscles: extensor carpi radialis, extensor digitorum longus (both flexed and extended), gluteus medius, longissimus lumborum, semitendinosus, and supraspinatus. Three examiners measured thickness of these muscles in five Thoroughbreds on 3 consecutive days. The day of measurement did not have any effect on the mean MT value of the muscles examined (P > .05). The left longissimus lumborum muscle was the only muscle for which the second measurement varied from the first and third (P < .05). The examiners had an effect on the mean coefficient of variation (CV) of the thickness of the flexed left extensor carpi radialis and flexed left extensor digitorum longus. The daily measurements varied more in the case of one of the examiners. Mean CVs higher or close to 10% were reported for both sides of the flexed extensor digitorum longus and for the supraspinatus muscles. The lowest CV was calculated for the longissimus lumborum and the extended semitendinosus (<5%). The largest disagreements between the examiners were observed for both sides of the flexed extensor digitorum longus and the supraspinatus (>10%–<20%). The best agreement was measured for the extended extensor carpi radialis and the longissimus lumborum (>3%–<7%). The results showed that for some muscles, it was difficult to locate the exact anatomical site for taking the MT measurements. To reduce CV, it was suggested that only one examiner should take all the measurements and the whole procedure must be such that it is as comfortable as possible for this particular examiner. 相似文献
996.
José A. Orden Ricardo De la Fuente María Yuste Susana Martínez-Pulgarín José A. Ruiz-Santa-Quiteria Pilar Horcajo Antonio Contreras Antonio Sánchez Juan C. Corrales Gustavo Domínguez-Bernal 《Canadian journal of veterinary research》2010,74(1):54-58
The presence of antibodies to the intimin β-binding region (Int280-β) of attaching and effacing Escherichia coli (AEEC) in serum from 20 goat kids from 2 herds, as well as in goat colostrum, was investigated by enzyme-linked immunosorbent assay. In addition, the onset and subsequent pattern of shedding of AEEC from the same goat kids over a 6-mo period was investigated. All the colostrum and serum samples tested contained antibodies against Int280-β. The association between the antibody titer and the isolation of AEEC suggests that antibodies to intimin β do not prevent colonization of the intestine by AEEC in goat kids. The AEEC were generally shed only transiently. Most AEEC isolated from the kids belonged to serogroup O26. Three isolates belonged to serogroup O157. These data show that goat kids may be a reservoir of AEEC that are potentially pathogenic for humans. 相似文献
997.
998.
The present paper refers to the cytometric analysis of lymphocytes T (with receptor CD5+), Th (with receptor CD4+), Tc/Ts (with receptor CD8+), lymphocytes CD25+ and lymphocytes B with receptor CD19+ in rabbits experimentally infected with strains of RHD virus--Rainham, Frankfurt and Asturias, not having haemagglutinogenic capacities, which makes them unique, as haemagglutinogenic capacity is a classic and typical property of most strains of this virus. The study was performed in the dynamic system, drawing blood samples from animals at hour 0, namely before the administration of the viral antigen, and then at 4, 8, 12, 24 and 36 h after the infection. The study indicated that Rainham and Asturias strains of RHD virus cause a similar amount of changes as the most immunogenic haemagglutinogenic strains CAMP V-561 and CAMP V-562 of the RHD virus do. In contrast, the Frankfurt strain of the RHD virus is characterised with 5-6-fold lower reactivity in this respect and is most similar to the least immunogenic haemagglutinogenic strain CAMP V-558 of the RHD virus. 相似文献
999.
Platt-Samoraj A Szweda W Procajło Z Wiśniewska M Otrocka-Domagała I 《Polish journal of veterinary sciences》2010,13(1):129-135
The aim of the study was to evaluate the anatomo- and histopathological lesions in internal organs of sows and their stillborn piglets after experimental Y. enterocolitica infection in different phases of pregnancy. Twelve pregnant sows were divided into 4 groups, infected per os on 33 (n = 3), 54 (n = 3) and 89 (n = 3) day of pregnancy with the pathogenic Y. enterocolitica strain isolated from the aborted swine fetus, and uninfected control group. Histopathological examinations of internal organs and intestine samples of stillborn piglets, slaughtered sows and samples of placentas were performed. Anatomo- and histopathological lesions were the most intense in the group of sows infected in the final phase of pregnancy, where the highest number of stillborn piglets was also found. Lesions of internal organs in stillborn piglets suggested a severe generalized bacterial infection. Although the analysis of experimental Y. enterocolitica infection of pregnant sows revealed that the most intense clinical, anatomopathological and histopathological abnormalities were recorded in the group of animals infected in the final phase of pregnancy. Infection in the first phase of pregnancy could have had an influence on the formation of the granulomatous inflammation. Differences in anatomopathological lesions between infected and control animals suggest that the period of pregnancy in which the infection appears could have had an influence on the course of yersiniosis in pigs. 相似文献
1000.
Leyre Navarro-Núñez María L. Lozano Constantino Martínez Vicente Vicente José Rivera 《Fitoterapia》2010
α2β1 and αIIbβ3 integrins, that support platelet adhesion to collagen and fibrinogen, respectively, share common signaling molecules. The effect of quercetin on platelet static adhesion to collagen and fibrinogen was assessed and correlated with its kinase inhibitory activity. Quercetin strongly abrogated PI3K and Src kinases, mildly inhibited Akt1/2, and slightly affected PKC, p38 and ERK1/2. Quercetin or the combined use of adenosine diphosphate and thromboxane A2 inhibitors abrogated platelet spreading on these surfaces to a similar extent. We suggest that the inhibitory effect of quercetin on platelet kinases blocks early signaling events preventing a complete platelet spreading. 相似文献