全文获取类型
收费全文 | 187416篇 |
免费 | 9725篇 |
国内免费 | 144篇 |
专业分类
林业 | 8252篇 |
农学 | 5891篇 |
基础科学 | 1116篇 |
22863篇 | |
综合类 | 33431篇 |
农作物 | 7471篇 |
水产渔业 | 9115篇 |
畜牧兽医 | 94495篇 |
园艺 | 2512篇 |
植物保护 | 12139篇 |
出版年
2018年 | 2567篇 |
2017年 | 2870篇 |
2016年 | 2647篇 |
2015年 | 2244篇 |
2014年 | 2827篇 |
2013年 | 7072篇 |
2012年 | 5177篇 |
2011年 | 6410篇 |
2010年 | 4155篇 |
2009年 | 4232篇 |
2008年 | 6289篇 |
2007年 | 6033篇 |
2006年 | 5607篇 |
2005年 | 5276篇 |
2004年 | 5003篇 |
2003年 | 5150篇 |
2002年 | 4664篇 |
2001年 | 5572篇 |
2000年 | 5689篇 |
1999年 | 4553篇 |
1998年 | 1956篇 |
1997年 | 1874篇 |
1996年 | 1704篇 |
1995年 | 2109篇 |
1994年 | 1807篇 |
1993年 | 1734篇 |
1992年 | 3587篇 |
1991年 | 3783篇 |
1990年 | 3778篇 |
1989年 | 3782篇 |
1988年 | 3462篇 |
1987年 | 3420篇 |
1986年 | 3502篇 |
1985年 | 3437篇 |
1984年 | 2796篇 |
1983年 | 2536篇 |
1982年 | 1724篇 |
1979年 | 2693篇 |
1978年 | 2168篇 |
1977年 | 1819篇 |
1976年 | 1837篇 |
1975年 | 1985篇 |
1974年 | 2416篇 |
1973年 | 2467篇 |
1972年 | 2384篇 |
1971年 | 2217篇 |
1970年 | 2139篇 |
1969年 | 2090篇 |
1968年 | 1765篇 |
1967年 | 1858篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
991.
A 5-year-old female Holstein cow was examined for ocular discharge, periorbital swelling, an area of full-thickness corneal cellular infiltrate, fibrin, hypopyon, diffuse corneal edema, and miosis. The patient was diagnosed with a corneal stromal abscess and secondary anterior uveitis. Histopathology, mycotic culture, and polymerase chain reaction positive for Aspergillus and Fusarium DNA confirmed the presence of fungal infection. Response to therapy was adequate, and follow-up with the patient 1 year after diagnosis revealed a focal area of corneal fibrosis. 相似文献
992.
Moeller EM Steiner JM Williams DA Tetrick M Burr J 《American journal of veterinary research》2006,67(7):1110-1114
OBJECTIVE: To determine an optimal dose of carbon 13 ((13)C)-labeled aminopyrine for use in a (13)C-aminopyrine demethylation blood test in healthy dogs. ANIMALS: 9 adult dogs. PROCEDURES: Food was withheld from each dog for 12 hours. A 2-mL baseline blood sample was obtained from each dog and placed into an evacuated tube containing sodium heparin. Carbon 13-labeled aminopyrine was administered IV at doses of 1, 2, 5, or 10 mg/kg. Additional blood samples (2 mL) were obtained and placed into evacuated tubes containing sodium heparin 30, 45, 60, and 75 minutes after (13)C-aminopyrine administration. Hydrochloric acid was used to extract CO(2) from blood samples. The extracted gas was analyzed by fractional mass spectrometry to determine the percentage dose of (13)C administered as (13)C-aminopyrine and recovered in extracted gas (PCD). RESULTS: Gross evidence of clinical adverse effects was not detected in any dog after administration of (13)C-aminopyrine. The mean coefficient of variation (CV) for PCD was significantly lower than the mean CV for the summation of PCD values up to a given sampling time (CUMPCD). Mean PCD values among the 4 doses for each sample time were not significantly different. Administration of (13)C-aminopyrine at a dose of 2 mg/kg resulted in the lowest interindividual variability. CONCLUSIONS AND CLINICAL RELEVANCE: The PCD is superior to CUMPCD for the quantification of aminopyrine demethylation. Administration of (13)C-(13)C-aminopyrine at a dose of 2 mg/kg is appropriate for use in the (13)C-aminopyrine demethylation blood test in healthy dogs. 相似文献
993.
994.
Burns GA Ruby KL Debowes RM Seaman SJ Brannan JK 《Journal of veterinary medical education》2006,33(2):301-308
Data from focused studies and comprehensive surveys suggest that developing or enhancing non-technical (professional) skills will result in a more satisfied and successful veterinary student or veterinary graduate. The College of Veterinary Medicine at Washington State University has devoted considerable time, effort, and resources to augmenting the non-technical aspects of its curriculum while maintaining the traditional strengths of its DVM program. Here we summarize pertinent research and best-practice recommendations from a variety of sources and outline the steps that have been taken, with the underlying rationales, to integrate the teaching and modeling of non-technical (professional) competence throughout a four-year course of veterinary study. 相似文献
995.
Association between heterophil/lymphocyte ratio, a marker of 'resistance' to stress, and some production and fitness traits in chickens 总被引:2,自引:0,他引:2
1. A stock of cross-bred CD hens was divided into 'resistant' (R) and 'sensitive' (S) to stress on the basis of the heterophil/lymphocyte (H/L) ratio using the lower 99% confidence limit method for selection. A first generation was produced from these R and S females mated with similarly selected R and S local Barred males. The association between 'resistance' and some production traits was investigated. 2. The proportions of R:S among CD females and Barred males was 51.2:48.8 and 52:48, respectively. Mean H/L ratios for Barred males and females, respectively, were 0.87 +/- 0.03 and 0.83 +/- 0.03 (P > 0.05). 3. Compared with the S group in CD females, the R group had greater egg production (59% vs 51%), egg weight (65.5 g vs 62.6 g) and body weight at 39 weeks (115 g heavier). 4. The superiority of R in terms of proportion of fertile eggs, hatchability and the proportion hatched from those set amounted to 4.8, 6.1 and 5.4%, respectively. 5. The proportion of dead embryos in the R group (5.4%) was lower than in the S group (9.3%). 6. With the F1 generation the R chicks were heavier at hatching. 7. Percentage mortality of male F1 chicks, from hatching to 4 weeks and from 4 to 8 weeks, was lower in the R group. A similar, but non-significant, trend was noted for R females. 8. The progeny of the R group was heavier than the S progeny at 4 and 8 weeks and also the percentage dressed weight of males was greater at 8 weeks. The R group was heavier than the S group at 4, 8 and 12 weeks. 9. These results suggest that selection for general 'resistance', on the basis of the H/L ratio using the 99% lower confidence limit method of selection, is positively correlated with several important production and reproduction traits. Establishing resistant lines with high production rates seems feasible. 相似文献
996.
1. The lactoperoxidase system (LPS) and thermal treatments have been shown to inactivate some micro-organisms in foods. However, further studies are needed to evaluate whether these treatments influenced the physical and sensory characteristics of treated samples. 2. A solution that contained 1% acetic acid and 3% salt with pH adjusted to 4 was developed as a standard marinade. The LPS consisting of 1 microg/ml lactoperoxidase (LP), 5.9 mM potassium thiocyanate (KSCN) and 2.5 mM hydrogen peroxide (H2O2) was added to the marinade for the LPS treatments. 3. In the thermal treatment, samples were heated with the marinade solution at 58 degrees C for 2 min and then marinated at 4 degrees C for 18 h, while the non-thermal treatments were marinated at 4 degrees C for 18 h. 4. For sensory evaluation, flavouring agents including 0.3% black pepper and 0.15% garlic powder were added to the marinade. For physical evaluation, no flavouring agents were added. 5. The results showed that combined LPS and thermal treatment did not impair the physical or sensory qualities of the samples. 6. In conclusion, marinated broiler drumsticks treated with LPS and thermal treatment had acceptable physical and sensory qualities. 相似文献
997.
Takagi M Takagaki K Kamimura S Zizhohara K Miyoshi A Yasuda Y Kawasaki Y Endo Y Ohishi A Yasumura E Deguchi E 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2006,53(6):296-299
An 8-month-old Japanese Black heifer with severe erythropoietic symptoms was subjected to clinical, histological and cytological examinations. During the 1 month clinical observation period, severe increases in RBC count, packed cell volume and haemoglobin concentration were observed. The plasma erythropoietin (Epo) concentration of the heifer (20.7 mIU/ml) was similar to that observed in normal control heifers. Blood gas examinations of the arterial and venous blood revealed low levels of partial pressure O(2) (PaO(2)), partial pressure CO(2) (PaCO(2)) and O(2) saturation (SaO(2)), while the blood pH was within the normal range. Gross lesions could not be detected. However, microscopic observation revealed severe proliferation of erythroblasts in the bone marrow and in the spleen without evidence of neoplastic changes. Based on these clinical and pathological examinations, we diagnosed the heifer as being the first case of primary erythrocytosis in Japanese Black cattle. 相似文献
998.
Immunohistochemical identification and pathologic findings in natural cases of equine abortion caused by leptospiral infection 总被引:1,自引:0,他引:1
The aim of this study was to examine the utility of immunohistochemistry (IHC) in the diagnosis of leptospiral equine abortion and to compare IHC to silver staining and serology of the aborted mares. Ninety-six fetuses from 57 farms were examined using all 3 diagnostic techniques, revealing evidence of leptospiral infection in 3 fetuses (3.1%) from 3 (5.3%) different farms. A new finding in 1 of these confirmed cases of leptospiral abortion was the presence of macroscopic pinpoint grayish-white nodules that had a histologic correlate of hepatic necrosis; other histologic findings were consistent with those previously reported. IHC performed using 2 different leptospiral antisera (multivalent whole-cell rabbit antiserum and rabbit antiserum against the major outer membrane protein LipL32) yielded similar results. IHC was more sensitive (19/21 [90.5%] tissue samples) than silver staining (8/21 [38.1%] tissue samples), and more specific than serology performed using the microscopic agglutination test. The primary advantage of IHC over silver staining was the ability of IHC to identify leptospiral antigen not only as morphologically intact spiral forms. 相似文献
999.
Monge A Elvira L Gonzalez JV Astiz S Wellenberg GJ 《Research in veterinary science》2006,80(1):120-125
In more than 10 Spanish dairy cows, a bovine herpesvirus 4 (BHV4) associated postpartum metritis was confirmed by virus isolation, BHV4-glycoprotein B (gB) PCR and/or serology. In this study, 12 cows with, and, at the time of sampling, 3 cows without clinical signs of acute postpartum metritis from one large dairy herd in Spain were examined for bacterial and viral infections. Blood, placenta/caruncles and uterine contents were collected between day 1 and day 20 post-calving, and examined for the presence of bacteria and for viruses by virus isolation, BHV4 DNA by BHV4-gB PCR and/or BHV4 antibody titres. Bovine herpesvirus 4 was detected in 83% of the cases with clinical signs of acute postpartum metritis by virus isolation and/or BHV4-gB PCR. An increase of BHV4 antibodies was detected in all examined postpartum metritis cows and in the 3 cows without clinical metritis. Two of these 3 cows developed severe metritis a few dayss after collecting the first blood sample. A concurrent infections of BHV4 and bacteria, mainly Arcanobacterium pyogenes and Streptococcus sp., were detected in 73% of the examined uterine contents collected from postpartum metritis affected cows. This case-report study showed a clear association between BHV4 infections and acute postpartum metritis in dairy cows. In addition, the BHV4-associated postpartum metritis appeared to be an emerging syndrome in this Spanish herd. 相似文献
1000.
In humans and animals, ossifying fibroma is a benign neoplasm that most frequently affects the mandible, often resulting in cosmetic deformities and malocclusion. It is considered rare in animals and most frequently affects young horses. A surgical biopsy of a solitary mass located beneath the gingiva in the right maxillary region, which had overgrown teeth and expanded the adjacent hard palate from a 6-year-old miniature Rex rabbit was submitted for light microscopic examination. The submitted incisional biopsy specimen was pale pink, firm, and nodular. Histopathologically, the neoplasm was composed of fibroblastic cells separated by abundant collagen. The neoplastic cells were interwoven with osteoblasts surrounding islands of mineralized, bony matrix containing few, widely spaced, often empty, lacunae. Minimal inflammation was present. Based on the histopathologic features, the tumor was diagnosed as an ossifying fibroma. To our knowledge, this is the first report of an ossifying fibroma in a rabbit. 相似文献