全文获取类型
收费全文 | 15160篇 |
免费 | 793篇 |
国内免费 | 19篇 |
专业分类
林业 | 886篇 |
农学 | 489篇 |
基础科学 | 96篇 |
2644篇 | |
综合类 | 2343篇 |
农作物 | 974篇 |
水产渔业 | 1265篇 |
畜牧兽医 | 5767篇 |
园艺 | 359篇 |
植物保护 | 1149篇 |
出版年
2023年 | 90篇 |
2022年 | 178篇 |
2021年 | 277篇 |
2020年 | 324篇 |
2019年 | 323篇 |
2018年 | 355篇 |
2017年 | 388篇 |
2016年 | 399篇 |
2015年 | 355篇 |
2014年 | 457篇 |
2013年 | 756篇 |
2012年 | 914篇 |
2011年 | 1134篇 |
2010年 | 601篇 |
2009年 | 584篇 |
2008年 | 963篇 |
2007年 | 938篇 |
2006年 | 861篇 |
2005年 | 838篇 |
2004年 | 856篇 |
2003年 | 777篇 |
2002年 | 712篇 |
2001年 | 264篇 |
2000年 | 239篇 |
1999年 | 184篇 |
1998年 | 122篇 |
1997年 | 97篇 |
1996年 | 90篇 |
1995年 | 88篇 |
1994年 | 78篇 |
1993年 | 76篇 |
1992年 | 98篇 |
1991年 | 92篇 |
1990年 | 103篇 |
1989年 | 110篇 |
1988年 | 86篇 |
1987年 | 103篇 |
1986年 | 74篇 |
1985年 | 75篇 |
1984年 | 72篇 |
1983年 | 77篇 |
1982年 | 41篇 |
1981年 | 51篇 |
1980年 | 54篇 |
1979年 | 49篇 |
1978年 | 57篇 |
1976年 | 50篇 |
1975年 | 43篇 |
1974年 | 46篇 |
1973年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
21.
David Lipsitz DVM Robin E. Levitski DVM Wayne L. Berry BVSc MMedVet 《Veterinary radiology & ultrasound》2001,42(1):14-19
Three dogs with multilobular osteochondrosarcoma of the skull were evaluated using magnetic resonance (MR) imaging. Spin echo T1, T2, proton weighted and post contrast T1W images were obtained with a 1.5 Tesla magnet. The MR imaging findings were similar in all three dogs with mixed signal intensities in the T1W, T2W and proton weighted images and fairly large areas of contrast enhancement in the post contrast T1W images. The extent of brain and soft tissue involvement were well delineated and provided useful information concerning surgical planning. MR imaging provided a useful method of evaluating dogs with skull tumors. 相似文献
22.
H K Pradhan G C Mohanty W Y Lee B Patnaik 《Veterinary immunology and immunopathology》1991,29(3-4):229-238
Antibody directed against Marek's disease-associated tumor surface antigen (MATSA) was eluted from tumor cells of lymphomas and peripheral blood lymphocytes that were isolated from Marek's disease virus-infected chickens. Feather follicular Marek's disease virus (MDV) antigen could not be demonstrated with this antibody by indirect immunofluorescent (IF) staining. Monoclonal antibody directed against MATSA could completely block the activity of eluted antibody and vice versa. By indirect IF staining using eluted antibody and fluorescein isothiocyanate (FITC) labelled antichicken globulin conjugate. MATSA-bearing cells were detected in MDV infected and herpes virus of turkey (HVT) vaccinated birds. Blocking of immunoglobulin molecules present on B-cells by anti-chicken globulin is critical in this test. 相似文献
23.
David A. Detweiler David S. Biller DVM James J. Hoskinson DVM Kenneth R. Harkin DVM 《Veterinary radiology & ultrasound》2001,42(2):108-112
Canine dysautonomia is an idiopathic condition resulting in loss of autonomic nervous system function. Recently, the prevalence of dogs diagnosed with dysautonomia in the mid-western United States has increased. In this study the medical records and radiographic findings in 24 dogs with dysautonomia were reviewed. A diagnosis of dysautonomia was made in 17 (71%) of the dogs in this study by postmortem examination, the remaining 7 (29%) dogs were diagnosed pharmacologically. The radiographic findings supportive of dysautonomia include aspiration pneumonia, megaesophagus, or a distended stomach, small bowel, or urinary bladder. In some instances, the disease radiographically mimicked other disorders of the gastrointestinal tract, including mechanical obstruction. 相似文献
24.
Marie Engel David W. Hird Tim E. Carpenter Martin Wierup 《Preventive veterinary medicine》1995,24(4):245-252
A cohort of 53 swine seronegative to Aujeszky's disease virus (ADV) was monitored in a 1 year study of a chronically infected commercial Swedish weaner pig producing herd. Serum samples were acquired from all 134 adult swine and analyzed by enzyme-linked immmunosorbent assay (ELISA). Animals testing negative, along with introduced replacement gilts, were followed serologically every second month. Movements of animals were recorded for 319 days and exposure to seropositive animals was calculated for each seronegative pig in the cohort. The accumulated daily pig contact between the 53 ADV-non-infected swine and 43 infected swine was 35 660 days and the median number of days in contact for the non-infected swine with infected was 222. Despite the frequent contact with seropositive pigs, no seronegative animals seroconverted during the first 11 months of observation. Forty-six of 53 pigs seroconverted after a clinical outbreak during the twelfth month of observation. 相似文献
25.
Susan J. Holcombe VMD MS Alicia L. Bertone DVM PhD David S. Biller DVM Valerie Haider DVM 《Veterinary radiology & ultrasound》1995,36(2):119-125
The purpose of this study was to define normal gross anatomic structures in the equine stifle with magnetic resonance images. Magnetic resonance (MR) images were made in sagittal, 15° supinated, transverse, and dorsal planes of two equine stifles. The MR images were scrutinized by comparing MR images to dissection specimens and frozen cross sections of stifle joints. Sagittal and 15° supinated images were the most valuable in assessing articular cartilage, subchondral bone, and soft tissue structures within the joint. Cranial and caudal cruciate ligaments, medial and lateral menisci, meniscotibial and meniscofemoral ligaments, long digital extensor tendon, and patellar ligaments were easily evaluated. MR images provided substantially more gross anatomical information than the currently available imaging modalities. 相似文献
26.
27.
28.
29.
30.