全文获取类型
收费全文 | 5673篇 |
免费 | 234篇 |
国内免费 | 8篇 |
专业分类
林业 | 480篇 |
农学 | 212篇 |
基础科学 | 51篇 |
1327篇 | |
综合类 | 732篇 |
农作物 | 251篇 |
水产渔业 | 358篇 |
畜牧兽医 | 1909篇 |
园艺 | 170篇 |
植物保护 | 425篇 |
出版年
2023年 | 28篇 |
2022年 | 52篇 |
2021年 | 97篇 |
2020年 | 111篇 |
2019年 | 138篇 |
2018年 | 105篇 |
2017年 | 124篇 |
2016年 | 133篇 |
2015年 | 94篇 |
2014年 | 145篇 |
2013年 | 266篇 |
2012年 | 322篇 |
2011年 | 393篇 |
2010年 | 247篇 |
2009年 | 203篇 |
2008年 | 344篇 |
2007年 | 342篇 |
2006年 | 359篇 |
2005年 | 360篇 |
2004年 | 319篇 |
2003年 | 294篇 |
2002年 | 308篇 |
2001年 | 78篇 |
2000年 | 71篇 |
1999年 | 87篇 |
1998年 | 66篇 |
1997年 | 54篇 |
1996年 | 53篇 |
1995年 | 44篇 |
1994年 | 28篇 |
1993年 | 44篇 |
1992年 | 36篇 |
1991年 | 36篇 |
1990年 | 39篇 |
1989年 | 43篇 |
1988年 | 37篇 |
1987年 | 28篇 |
1986年 | 19篇 |
1985年 | 33篇 |
1984年 | 23篇 |
1983年 | 35篇 |
1982年 | 21篇 |
1981年 | 18篇 |
1980年 | 19篇 |
1979年 | 14篇 |
1978年 | 20篇 |
1977年 | 18篇 |
1974年 | 16篇 |
1973年 | 22篇 |
1972年 | 16篇 |
排序方式: 共有5915条查询结果,搜索用时 15 毫秒
141.
142.
143.
Sting R Kopp J Mandl J Seeh C Seemann G Kimmig P Schmitt K Mentrup T 《Berliner und Münchener tier?rztliche Wochenschrift》2002,115(9-10):360-365
Investigations of 1167 dairy cows out of 105 herds with fertility disorders on secretion of Coxiella burnetii (C. burnetii) by the genitals as well as serological studies of these animals using ELISA demonstrated that C. burnetii infections are significantly associated with abortions but not with repeated inseminations without success or vaginal excretions. The demonstration of an increased risk of infections for persons caring for those dairy herds could be shown by a total of 253 serological studies. A comparison of these studies of farmers caring for dairy herds suffering from abortions a seroprevalence of > or = 20% showed that these persons revealed significantly more frequent antibodies against C. burnetii than farmers of the group compared with. Further studies showed that in herds suffering from abortions a seroprevalence of > or = 20% means an additional risk of infections of farmers. Vice versa abortions of the cows in herds with a seroprevalence of > or = 20% imply an additional infectious risk. 相似文献
144.
Wagner AE Walton JA Hellyer PW Gaynor JS Mama KR 《Journal of the American Veterinary Medical Association》2002,221(1):72-75
OBJECTIVE: To compare indicators of postoperative pain and behavior in dogs with and without a low-dose ketamine infusion added to usual perioperative management. DESIGN: Prospective, randomized, blinded clinical study. ANIMALS: 27 dogs undergoing forelimb amputation. PROCEDURE: Dogs were anesthetized with glycopyrrolate, morphine, propofol, and isoflurane. Thirteen dogs were treated with ketamine IV, as follows: 0.5 mg/kg (0.23 mg/lb) as a bolus before surgery, 10 microg/kg/min (4.5 microg/lb/min) during surgery, and 2 microg/kg/min (0.9 microg/lb/min) for 18 hours after surgery. Fourteen dogs received the same volume of saline (0.9% NaCl) solution. All dogs received an infusion of fentanyl (1 to 5 microg/kg/h [0.45 to 2.27 pg/lb/h]) for the first 18 hours after surgery. Dogs were evaluated for signs of pain before surgery, at the time of extubation, and 1, 2, 3, 4, 12, and 18 hours after extubation. Owners evaluated their dogs' appetite, activity, and wound soreness on postoperative days 2, 3, and 4. RESULTS: Dogs that received ketamine infusions had significantly lower pain scores 12 and 18 hours after surgery and were significantly more active on postoperative day 3 than dogs that received saline solution infusions. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that perioperative administration of low doses of ketamine to dogs may augment analgesia and comfort in the postoperative surgical period. 相似文献
145.
146.
Zur G Ihrke PJ White SD Kass PH 《Veterinary therapeutics : research in applied veterinary medicine》2002,3(1):88-96
Antihistamines were prescribed for 178 of 271 dogs with a diagnosis of atopic dermatitis at the Veterinary Medical Teaching Hospital of the University of California, Davis from 1992 to 1998. Fifty-four percent of 166 dogs given antihistamines responded favorably to these treatments, with 27% of the responses rated as good and 27% rated as moderate. Diphenhydramine and hydroxyzine were the most commonly used antihistamines and were the most frequently effective. Chlorpheniramine and clemastine were administered less frequently and had much lower positive response rates. Responses to antihistamines as a group were significantly better in dogs having onset of clinical signs at younger ages (odds ratios for 1-year increase in age = 0.72, 95% confidence interval = 0.57 to 0.91, P =.005). 相似文献
147.
Presence of human Giardia in domestic,farm and wild animals,and environmental samples suggests a zoonotic potential for giardiasis 总被引:2,自引:0,他引:2
van Keulen H Macechko PT Wade S Schaaf S Wallis PM Erlandsen SL 《Veterinary parasitology》2002,108(2):97-107
Giardia lamblia which parasitize humans belong to either of two genotypes, A or B, based on specific signature sequences in the 5' end of the small subunit (16S) ribosomal RNA (rRNA) gene. These two genotypes also were found in cysts from fecal samples of animal origin such as dogs, cats, some farm animals and wild animals. In addition, trophozoites recovered from cysts obtained from environmental samples belonged to these two genotypes as well, suggesting that the G. lamblia genotypes A and B are widespread and possibly zoonotic. Trophozoites were recovered from rats and these isolates might belong to another genotype of G. lamblia. Deer mice and one dog appeared to be parasitized by genotypes of Giardia with close affinity to G. microti. This species, therefore, also consists of a genotype complex. 相似文献
148.
A study was conducted to determine the prevalence and possible significance of campylobacteria in pig abortions in Denmark. Surface-cauterised liver and kidney samples from 55 aborted pig fetuses submitted to the Danish Veterinary Laboratory were taken and a sensitive isolation procedure used to examine pooled tissue samples for Campylobacter, Arcobacter and Helicobacter spp. Routine microbiological, immunological, and histopathological examinations were also performed to identify concurrent infections or histopathological changes. The abortions tested negative for established abortifacient pathogens (Brucella, Leptospira, PPV, PRRSV), but Arcobacter spp. were recovered from 23/55 abortions. Co-infections with Streptococcus suis, Escherichia coli, and haemolytic streptococci were observed in 7/23 Arcobacter-positive fetuses, and in 4/32 Arcobacter-negative fetuses. Histopathological analyses identified placentitis, pneumonia, hepatitis and encephalitis among the study group. However, no obvious pathologic features were solely associated with Arcobacter-positive cases, nor were Arcobacter-like bacteria observed in tissue samples. Protein profile analyses of the 27 Arcobacter isolates identified 11 as A. cryaerophilus and 10 as A. skirrowii. Six strains could not be classified into any existing species and were phenotypically distinct, thus, potentially representing at least one new species. The identification results showed that multiple taxa could be found in a single fetus, and in distinct aborted fetuses from a single sow. The high prevalence of arcobacters in Danish pig abortions may account for at least some of the >90% of cases in which no established abortifacient agent is detected, but further studies are needed to define the role of each species, especially where co-infections with other bacteria are present. 相似文献
149.
Bennett PF DeNicola DB Bonney P Glickman NW Knapp DW 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2002,16(1):100-104
A retrospective study of 43 dogs with anal sac adenocarcinoma (ASAC) was performed to characterize the clinical presentation and response to treatment. Clinical signs at presentation varied considerably, with signs related either to sublumbar nodal metastasis (tenesmus or constipation) or hypercalcemia (polyuria-polydipsia and anorexia) being the most frequent findings. At the time of presentation, 23 (53%) dogs had hypercalcemia and 34 (79%) had metastases, with the regional lymph nodes (31 dogs, 72%) being the most common site of metastasis. A variety of chemotherapeutic agents were administered, with partial remission (PR) recorded in 4 of 13 (31%) dogs treated with cisplatin and in 1 of 3 (33%) dogs treated with carboplatin. The median survival for all dogs was 6 months (range, 2 days-41 months). There was no statistical association between the presence of hypercalcemia and survival, although the power of the study to detect an increase in survival of 3 months was low (.33). We conclude that platinum chemotherapy has antitumor activity in canine apocrine gland carcinoma and that further study of these agents is warranted. 相似文献
150.
An optimized system of computerized image analysis was used to investigate variations in the adherence of Staphylococcus intermedius to canine corneocytes from four different breed groups and six different anatomical sites. S. intermedius showed significantly greater adherence to the head and neck compared with the dorsum, but adherence to the limb, axilla and groin did not differ from other sites. Furthermore, there was significantly greater adherence of S. intermedius to corneocytes from the dorsum, forelimb, axilla and groin of Boxers and Bull Terriers than Spaniels and Hounds. S. intermedius, and also Pseudomonas aeruginosa, exhibited abundant adherence, which was significantly greater than Staphylococcus aureus, Streptococcus canis, Klebsiella pneumoniae and Escherichia coli. In addition, S. intermedius adherence demonstrated a sigmoid dose-response curve with increasing bacterial concentration. These results suggest that S. intermedius adheres to canine corneocytes by a specific receptor-ligand interaction and adheres to the skin of some breeds more avidly than others. However, variations in adherence between body regions would not account for the predilection sites of canine bacterial pyoderma. 相似文献