全文获取类型
收费全文 | 6390篇 |
免费 | 48篇 |
国内免费 | 27篇 |
专业分类
林业 | 217篇 |
农学 | 45篇 |
基础科学 | 9篇 |
951篇 | |
综合类 | 1161篇 |
农作物 | 119篇 |
水产渔业 | 85篇 |
畜牧兽医 | 3633篇 |
园艺 | 26篇 |
植物保护 | 219篇 |
出版年
2022年 | 9篇 |
2018年 | 16篇 |
2014年 | 11篇 |
2013年 | 12篇 |
2012年 | 511篇 |
2011年 | 689篇 |
2010年 | 117篇 |
2009年 | 88篇 |
2008年 | 518篇 |
2007年 | 548篇 |
2006年 | 496篇 |
2005年 | 507篇 |
2004年 | 498篇 |
2003年 | 469篇 |
2002年 | 418篇 |
2001年 | 250篇 |
2000年 | 328篇 |
1999年 | 115篇 |
1998年 | 20篇 |
1997年 | 17篇 |
1996年 | 13篇 |
1995年 | 19篇 |
1994年 | 27篇 |
1993年 | 55篇 |
1992年 | 50篇 |
1991年 | 89篇 |
1990年 | 27篇 |
1989年 | 46篇 |
1988年 | 25篇 |
1987年 | 28篇 |
1986年 | 22篇 |
1985年 | 19篇 |
1984年 | 19篇 |
1983年 | 23篇 |
1982年 | 19篇 |
1981年 | 12篇 |
1980年 | 14篇 |
1979年 | 9篇 |
1977年 | 10篇 |
1974年 | 8篇 |
1970年 | 8篇 |
1967年 | 10篇 |
1966年 | 8篇 |
1963年 | 14篇 |
1960年 | 10篇 |
1958年 | 9篇 |
1957年 | 9篇 |
1948年 | 11篇 |
1935年 | 8篇 |
1907年 | 8篇 |
排序方式: 共有6465条查询结果,搜索用时 1 毫秒
941.
Rishniw M Ljungvall I Porciello F Häggström J Ohad DG 《Research in veterinary science》2012,93(2):965-969
Respiratory rate monitoring of cardiac patients is recommended by many cardiologists. However, little objective data exist about respiratory rates in apparently healthy dogs when collected in the home environment. We measured sleeping respiratory rates (SRR) in apparently healthy dogs and compared sleeping and resting respiratory rates (RRR) with a cross-sectional prospective study. Participants collected 12-14 one-minute SRR over a period ranging from 1 week to 2 months on 114 privately owned adult dogs. Selected participants simultaneously collected RRR. Mean within-dog average SRR (SRR(mean)) was 13breaths per minute (breaths/min). No dog had SRR(mean) >23 breaths/min; three dogs had instantaneous SRR measurements >30 breaths/min. Dogs had higher RRR(mean) (19 breaths/min) than SRR(mean) (15 breaths/min) (P<0.05). Canine SRR(mean) was unaffected by age, bodyweight or geographic location. Data acquisition was considered relatively simple by most participants. This study shows that apparently healthy adult dogs generally have SRR(mean) <30 breaths/min and rarely exceed this rate at any time. 相似文献
942.
La Ragione RM Best A Aktan I Clifton-Hadley FA Dugdale AH Weyer U Crawley T Townsend P Cooley WA Johnson L Wangoo A Woodward MJ Wales AD 《Research in veterinary science》2012,93(1):42-45
Escherichia coli O115 has been isolated from healthy sheep and was shown to be associated with attaching-effacing (AE) lesions in the large intestine. Following previous observations of interactions between E. coli O157 and O26, the aim of the present study was to assess what influence an O115 AE E. coli (AEEC) would have on E. coli O157 colonisation in vitro and in vivo. We report that E. coli O115- and O157-associated AE lesions were observed on HEp-2 cells and on the mucosa of ligated ovine spiral colon. In single strain inoculum, E. coli O115 associated intimately with HEp-2 cells and the spiral colon in greater numbers than E. coli O157:H7. However, in mixed inoculum studies, the number of E. coli O115 AE lesions was significantly reduced suggesting negative interference by E. coli O157. Use of the ligated colon model in the present work has allowed in vitro observations to be extended and confirmed whilst using a minimum of experimental animals. The findings support a hypothesis that some AEEC can inhibit adhesion of other AEEC in vivo. The mechanisms involved may prove to be of utility in the control of AE pathovars. 相似文献
943.
Turan N Yildirim F Altan E Sennazli G Gurel A Diallo I Yilmaz H 《Research in veterinary science》2012,93(3):1504-1507
The aim of the present study was to investigate abortion storms that occurred in the Marmara region of Turkey in 2008-2009 using a real-time PCR. Two aborted foetuses were necropsied and histo-pathological findings reported herein. Ten lungs, 3 brains and one nasal swab from 10 aborted foetuses, 6 nasal swabs and 3 vaginal swabs from aborting mares were included in this study. EHV-1 was isolated from the lung, liver and brain of 1 aborted foetus. EHV-1 DNA was detected in the lungs, livers and spleens of 2 necropsied foetuses and in 3 lungs from 10 foetuses submitted for diagnosis. A brain from one of the aborted foetuses was also positive for EHV-1 DNA. EHV-4 DNA was detected only in a nasal swab of one of the tested foetuses. Neither EHV-1 nor EHV-4 DNA was detected in the swabs of aborting mares. Sequence analysis of the glycoprotein B of the strains was performed and a phylogenetic tree was generated. The results indicated that 4 of the 5 Turkish EHV-1 strains (TR02, TR03, TR04 and TR05) clustered together; the fifth strain (TR01) was slightly removed from the group and clustered with other EHV-1 from various origins. Single nucleotide polyporphism (SNP in ORF30) associated with neuropathogenesis was not detected in any of the strains. At necropsy, sub-milier focal necrosis in the liver and spleen was observed. Microscopically, focal coagulation necrosis and marked eosinophilic intranuclear and intracytoplasmic inclusion bodies in the hepatocytes localised around the necrotic areas in the liver. Severe coagulation necrosis in white pulp of the spleen was also observed. 相似文献
944.
945.
946.
947.
A retrospective study of 275 anaesthetic records of cats was undertaken to examine the prevalence of postanaesthetic hypothermia, its clinical predictors and consequences. Temperature was recorded throughout anaesthesia. The temperature reached at the end was classified as hyperthermia (>39.50 °C), normothermia (38.50 to 39.50 °C), slight hypothermia (38.49 to 36.50 °C), moderate hypothermia (36.49 to 34.00 °C) or severe hypothermia (<34.00 °C). Statistical analysis consisted of multiple regression to identify the factors that affect the temperature at the end of the procedure. Before premedication, the mean (sd) temperature was 38.2 (1.0) °C. At 60, 120 and 180 minutes from induction, the temperature was 35.4 (1.4) °C, 35.0 (1.5) °C and 34.6 (1.5) °C, respectively. The prevalence of hypothermia was slight 26.5 per cent (95 per cent CI 21.7 to 32.0 per cent), moderate 60.4 per cent (95 per cent CI 54.5 to 66.0 per cent) and severe 10.5 per cent (95 per cent CI 7.4 to 14.7 per cent). The variables associated with a decrease in the temperature recorded at the end of anaesthesia were the duration of anaesthesia, the reason for anaesthesia (abdominal and orthopaedic surgeries significantly reduced the temperature when compared with minor procedures) and the anaesthetic risk (high-risk cats showed lower temperatures than low-risk cats). The temperature before premedication was associated with an increase in the final temperature. 相似文献
948.
Lameness scoring system for dairy cows using force plates and artificial intelligence 总被引:2,自引:0,他引:2
Ghotoorlar SM Ghamsari SM Nowrouzian I Ghotoorlar SM Ghidary SS 《The Veterinary record》2012,170(5):126
Lameness scoring is a routine procedure in dairy industry to screen the herds for new cases of lameness. Subjective lameness scoring, which is the most popular lameness detection and screening method in dairy herds, has several limitations. They include low intra-observer and inter-observer agreement and the discrete nature of the scores which limits its usage in monitoring the lameness. The aim of this study is to develop an automated lameness scoring system comparable with conventional subjective lameness scoring by means of artificial neural networks. The system is composed of four balanced force plates installed in a hoof-trimming box. A group of 105 dairy cows was used for the study. Twenty-three features extracted from ground reaction force (GRF) data were used in a computer training process which was performed on 60 per cent of the data. The remaining 40 per cent of the data were used to test the trained system. Repeatability of the lameness scoring system was determined by GRF samples from 25 cows, captured at two different times from the same animals. The mean sd was 0.31 and the mean coefficient of variation was 14.55 per cent, which represents a high repeatability in comparison with subjective vision-based scoring methods. Although the highest sensitivity and specificity values were seen in locomotion score groups 1 and 4, the automatic lameness system was both sensitive and specific in all groups. The sensitivity and specificity were higher than 72 per cent in locomotion score groups 1 to 4, and it was 100 per cent specific and 50 per cent sensitive for group 5. 相似文献
949.
950.
Lynen G Yrjö-Koskinen AE Bakuname C Di Giulio G Mlinga N Khama I Hanks J Taylor NM James AD McKeever D Peters AR Rushton J 《Tropical animal health and production》2012,44(3):567-572
East Coast fever (ECF) causes considerable mortality and production losses in the Tanzania smallholder dairy sector and limits the introduction of improved dairy breeds in areas where the disease is present. The infection and treatment method (ITM) was adopted by smallholder dairy farms for ECF immunisation in Hanang and Handeni districts of Tanzania. This study recorded incidence rates for ECF and other tick-borne diseases (TBDs) for ECF-immunised and non-immunised cattle between 1997 and 2000. Approximately 80% of smallholder households from both sites (n?=?167) participated in this longitudinal study, with immunisations carried out at the request of the livestock owners. Efficacy of ITM for preventing ECF cases in these crossbred dairy cattle was estimated at 97.6%, while that for preventing ECF deaths was 97.9%. One percent of the cattle developed clinical ECF as a result of immunisation. Since ECF immunisation permits a reduction in acaricide use, an increase in other TBDs is a potential concern. Sixty-three percent of farmers continued to use the same acaricide after immunisation, with 80% of these reducing the frequency of applications. Overall, 78% of farmers increased the acaricide application interval after immunisation beyond that recommended by the manufacturer, resulting in annual savings in the region of USD 4.77 per animal. No statistical difference was observed between the immunised and non-immunised animals in the incidence of non-ECF TBDs. However, immunised animals that succumbed to these diseases showed fewer case fatalities. ITM would therefore appear to be a suitable method for ECF control in Tanzania's smallholder dairy sector. 相似文献