全文获取类型
收费全文 | 771篇 |
免费 | 27篇 |
专业分类
林业 | 26篇 |
农学 | 12篇 |
基础科学 | 2篇 |
57篇 | |
综合类 | 126篇 |
农作物 | 30篇 |
水产渔业 | 21篇 |
畜牧兽医 | 488篇 |
园艺 | 12篇 |
植物保护 | 24篇 |
出版年
2021年 | 10篇 |
2020年 | 7篇 |
2019年 | 10篇 |
2018年 | 6篇 |
2017年 | 10篇 |
2016年 | 6篇 |
2013年 | 26篇 |
2012年 | 13篇 |
2011年 | 33篇 |
2010年 | 23篇 |
2009年 | 18篇 |
2008年 | 25篇 |
2007年 | 20篇 |
2006年 | 27篇 |
2005年 | 23篇 |
2004年 | 19篇 |
2003年 | 16篇 |
2002年 | 22篇 |
2001年 | 29篇 |
2000年 | 23篇 |
1999年 | 20篇 |
1998年 | 11篇 |
1997年 | 12篇 |
1996年 | 16篇 |
1995年 | 9篇 |
1994年 | 16篇 |
1993年 | 15篇 |
1992年 | 28篇 |
1991年 | 19篇 |
1990年 | 16篇 |
1989年 | 19篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 14篇 |
1984年 | 15篇 |
1983年 | 9篇 |
1979年 | 15篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 10篇 |
1975年 | 5篇 |
1974年 | 15篇 |
1973年 | 6篇 |
1972年 | 10篇 |
1971年 | 11篇 |
1970年 | 10篇 |
1969年 | 8篇 |
1967年 | 7篇 |
1966年 | 6篇 |
排序方式: 共有798条查询结果,搜索用时 15 毫秒
11.
Aerobic bacterial populations were studied on the distal hair coat and at the skin surface of the shoulder, rump and abdomen of 10 healthy dogs. Coagulase negative staphylococci (CNS) were more frequently isolated from the hair than the skin at the shoulder and rump. There was no difference in the isolation rate of coagulase positive staphylococci (CPS) (Staphylococcus intermedius) between the hair and skin. Total skin counts were greatest on the abdomen whereas CNS counts from the hair were least at this site. There were no differences between CPS counts at the three sites on either hair or skin. The populations on the relatively unfavourable microenvironment of the distal hair may represent contamination rather than colonisation. The low populations of CPS at the skin surface also indicate contamination or transient colonisation rather than true resident status. 相似文献
12.
Fractures of the humerus 总被引:2,自引:0,他引:2
Simpson AM 《Clinical Techniques in Small Animal Practice》2004,19(3):120-127
Humeral fractures are the least common long bone fracture in small animals. The low incidence of these fractures combined with the unique anatomy of the humerus makes repair of humeral fractures challenging. This chapter provides a review of humeral fracture management. 相似文献
13.
The purpose of this study was to find out if an LMA (#1 LMA‐Classic) would provide a better airway than a face mask in spontaneously breathing anesthetized rabbits, and to test if it could be used for mechanically controlled ventilation. Sixteen rabbits (4.1 ± 0.8 kg, mean ± SD) were assigned randomly to three treatment groups; face mask with spontaneous ventilation (FM‐SV; n = 5), LMA with spontaneous ventilation (LMA‐SV; n = 5), and LMA with controlled ventilation (LMA‐CV; n = 6). Rabbits were anesthetized in dorsal recumbency using a circle circuit at constant ET isoflurane (2.3%, Datex airway gas monitor) and constant rectal temperature (38.85 °C) for 2 hours. PaCO2, PaO2, minute volume, tidal volume (Wright's respirometer), and Pe CO2 were measured at 15 minute intervals. Two individuals in the FM‐SV group had PaCO2 >100 mm Hg (>13.3 kPa). One rabbit in the FM‐SV had PaO2 <80 mm Hg (<10.7 kPa). All FM‐SV rabbits showed signs of airway obstruction and two were withdrawn from the study at 45 and 90 minutes, respectively, because of cyanosis. Tidal volume could not be measured in the FM‐SV group. No signs of airway obstructions were observed in either of the LMA groups. Four rabbits in the LMA‐CV group developed gastric tympany, and one of these refluxed after 110 minutes. The significance of differences between the two spontaneously breathing groups and between the two LMA groups were measured using Wilcoxon's rank sum test (with significance assumed at p < 0.05). There were no statistical differences between FM‐SV and LMA‐SV in any variable tested. PaCO2 and Pe ′CO2 were less in the LMA‐CV group than in the LMA‐SV group, while PaO2, tidal volume, and minute volume were all more. We conclude that biologically, the LMA provides a better airway than the face mask during spontaneous breathing and that it can be used for IPPV, but that gastric tympany is likely to occur during IPPV. 相似文献
14.
Tasker S Knottenbelt CM Munro EA Stonehewer J Simpson JW Mackin AJ 《The Journal of small animal practice》1999,40(10):473-478
Forty-two dogs with a history of persistent nasal disease were evaluated by a combination of clinical examination, thoracic and nasal radiography, retroflexed endoscopy and biopsy, and anterograde rhinoscopy and blind nasal biopsy. A definitive diagnosis was made in 91 per cent of cases. Neoplasia was the most common diagnosis (33 per cent of cases), followed by inflammatory rhinitis (24 per cent). Other diagnoses included periodontal disease (10 per cent), aspergillosis (7 per cent) and foreign bodies (7 per cent). Adenocarcinoma was the most common tumour diagnosed. The clinical findings were found to be too variable to be used as specific diagnostic criteria. Anterograde rhinoscopy and retroflexed endoscopy had higher specificity and sensitivity than radiology for the diagnosis of neoplasia, inflammatory rhinitis, aspergillosis and foreign bodies. With a systematic approach to the investigation of persistent nasal disease, a definitive diagnosis can be successfully obtained in the vast majority of cases. 相似文献
15.
16.
Simpson HV Simpson BH Simcock DC Reynolds GW Pomroy WE 《New Zealand veterinary journal》1999,47(1):20-24
AIMS: Both adult and larval Ostertagia circumcincta infections raise abomasal pH and serum gastrin and pepsinogen concentrations, either because of physical effects of the worms or from their chemical secretions. The study was designed to examine whether adult worms require contact with the gastric mucosa to effect changes in gastric secretion. METHODS: Abomasal pH and serum gastrin and pepsinogen concentrations were measured in four groups of sheep: Group A (n = 4): abomasal contents containing about 18,000 adult O. circumcincta were obtained from donor sheep, concentrated and infused into 5 microm mesh porous bags attached to surgically implanted abomasal cannulae. A second worm transplantation was carried out 1 week later to assess worm survival after 16 hours. Group B (n = 4): about 9000 adult worms, recovered after migration out of abomasal contents set in agar, were placed in small 5 microm mesh bags which were inserted through indwelling abomasal cannulae and left for 3 days. Group C (n = 2): about 3000 adult worms from the population recovered from agar were infused through abomasal cannulae which allowed. free movement in the abomasum. Group D (n = 3) was left uninfected. RESULTS: Worms transplanted directly into the abomasum (Group C) caused rapid and marked effects on abomasal secretion. Adult O. circumcincta died within 16 hours of transfer into the abomasum when they were restrained within porous bags. Nevertheless, in sheep receiving 18,000 worms, abomasal pH increased soon after new feed was presented on Days 1, 2 and 4 after worm transfer; serum gastrin was elevated in three sheep from 113 hours and serum pepsinogen increased in one animal. Sheep receiving 9000 worms showed similar trends but the results were equivocal. CONCLUSIONS: Adult O. circumcincta prevented from physical contact with the gastric mucosa by restraint in porous bags are able to raise abomasal pH. This study implicates parasite excretory-secretory products in mediating changes in gastric secretion caused by adult abomasal worms. 相似文献
17.
The effect of dose and line on immunisation of cattle with lymphoblastoid cells infected with Theileria annulata 总被引:1,自引:0,他引:1
H Ouhelli E A Innes C G Brown A R Walker S P Simpson R L Spooner 《Veterinary parasitology》1989,31(3-4):217-228
Thirty-one Friesian calves in Morocco susceptible to tropical theileriosis were protected against a lethal sporozoite challenge by prior infection with lymphoblastoid cell lines infected and transformed in vitro by a Moroccan stock of Theileria annulata. The challenge infection of cryopreserved sporozoites killed all four susceptible control calves within 20 days. Four schizont-infected cell cultures at Passage 3 were inoculated at four different doses, 10(8), 10(6), 10(4) and 10(2), into pairs of calves. The recipient animals showed great variation in severity of disease symptoms, which did not show a linear correlation with the cell dose inoculated. The most severe disease symptoms were recorded, prior to challenge, in the 10(2) cell dose recipients; one animal died of acute theileriosis and another had to be treated. One of the four cell lines used was more virulent than the other three. Two years after the completion of this experiment, immunised animals have shown normal productivity traits. 相似文献
18.
Christopher R. Lamb MA VetMB Kenneth W. Simpson BVM&S PhD 《Veterinary radiology & ultrasound》1995,36(2):139-145
Pancreatitis can be induced in dogs by intravenous infusion of supraphysiologic doses of synthetic cholecystokinin octapeptide (CCK-8). Eight anesthetized female beagles were given either CCK-8 or saline in a randomized, blinded fashion and had abdominal ultrasonography to study the development of pancreatic lesions. Pancreatic lesions were apparent 2 hours after the start of CCK-8 infusion and included swelling, interlobular and subcapsular fluid accumulation and patchy hypoechogenicity of the gland parenchyma. CCK-8 had a variable effect on gallbladder emptying. No signs of biliary obstruction or duodenal lesions were identified. Dogs given CCK-8 had severe edematous pancreatitis at necropsy six hours after the start of the infusion. Compared to the oleic acid model of pancreatitis, CCK-8 infusion induces a rapid onset of pancreatitis and an ultrasonographic appearance that reflects diffuse edema of the gland. The short time-scale of the experiment may account for the relative absence of secondary lesions affecting the biliary tract or duodenum compared to the naturally-occurring disease. 相似文献
19.
20.
Simpson GG 《Science (New York, N.Y.)》1970,170(3959):678