全文获取类型
收费全文 | 113169篇 |
免费 | 6260篇 |
国内免费 | 64篇 |
专业分类
林业 | 4617篇 |
农学 | 3776篇 |
基础科学 | 669篇 |
13552篇 | |
综合类 | 18789篇 |
农作物 | 4039篇 |
水产渔业 | 5775篇 |
畜牧兽医 | 59592篇 |
园艺 | 1344篇 |
植物保护 | 7340篇 |
出版年
2018年 | 1564篇 |
2017年 | 1728篇 |
2016年 | 1595篇 |
2015年 | 1333篇 |
2014年 | 1636篇 |
2013年 | 4182篇 |
2012年 | 3011篇 |
2011年 | 3614篇 |
2010年 | 2490篇 |
2009年 | 2467篇 |
2008年 | 3645篇 |
2007年 | 3478篇 |
2006年 | 3237篇 |
2005年 | 3056篇 |
2004年 | 2976篇 |
2003年 | 3098篇 |
2002年 | 2760篇 |
2001年 | 3782篇 |
2000年 | 3824篇 |
1999年 | 2964篇 |
1998年 | 1178篇 |
1997年 | 1174篇 |
1996年 | 1063篇 |
1995年 | 1350篇 |
1994年 | 1154篇 |
1993年 | 1110篇 |
1992年 | 2404篇 |
1991年 | 2590篇 |
1990年 | 2573篇 |
1989年 | 2490篇 |
1988年 | 2310篇 |
1987年 | 2347篇 |
1986年 | 2342篇 |
1985年 | 2201篇 |
1984年 | 1906篇 |
1983年 | 1626篇 |
1982年 | 1088篇 |
1979年 | 1694篇 |
1978年 | 1306篇 |
1977年 | 1204篇 |
1976年 | 1123篇 |
1975年 | 1218篇 |
1974年 | 1462篇 |
1973年 | 1486篇 |
1972年 | 1454篇 |
1971年 | 1325篇 |
1970年 | 1281篇 |
1969年 | 1282篇 |
1968年 | 1043篇 |
1967年 | 1153篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
山羊脑灰质软化症 (POLIOEN CEPHALOMALACIA)和李氏杆菌病 (LIS TERIOSIS)是症状相似治疗方法截然不同的两种疾病。山羊饲养者和兽医工作者必须从两种疾病的细微差别中进行鉴别 ,以便正确治疗和处理病羊。多数情况下 ,这两种疾病出现在饲养条件比较好、但饲养方法不当的地方。特别是在快速育肥时。精饲料喂量过多 ,而含粗纤维的饲料喂量过少是诱发两种疾病的重要因素。突然更换饲料常常导致此病突然发作。脑灰质软化症 (通常又称为大脑皮层坏死症 )是缺乏硫胺 (即维生素B1)而造成的一种代谢性疾病。瘤胃环… 相似文献
73.
74.
75.
76.
Russell T. Greene Gregory C. Troy 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1995,9(2):86-91
Coccidioidomycosis was diagnosed in 48 cats. Forty-one cases were identified within a period of 3 years. Coccidioides immitis was revealed by cytological or histopathological examinations, or culture in 70% of cats. The remaining 30% of cases were diagnosed by appropriate clinical signs, radiographic lesions, and serological test results. The average age of affected cats was 6.2 years with a median age of 5.0 years. Fifty-four percent (n = 26) were female and 46% (n = 22) were male. Domestic shorthaired and longhaired breeds comprised 89% (n = 41) of affected cats. Sixty-seven percent of cases were diagnosed during the 6-month period of December through May. Cats infected with C immitis were presented for evaluation of dermatologic (56%), respiratory (25%), musculoskeletal (19%), and neurological or ophthalmologic signs (19%). Fever, inappetence, and weight loss were present in 44% of the cats. Duration of clinical signs before diagnosis was less than 4 weeks in 85% (n = 42) of cats, with an average of 3.8 weeks and a median of 2 weeks. Agar gel immunodiffusion tests were positive in all 39 cats tested at sometime during the course of their disease. Hyperproteinemia (greater than 7.9 g/dL) was present in 52% (10/23) of cases. The majority of cats (n = 39) were negative for feline leukemia virus. Antibodies to feline immunodeficiency virus were absent in the 19 cats tested. Ketoconazole was the most common antifungal agent used to treat cats with Coccidioidomycosis. Duration of treatment ranged from less than 1 week to 43 months. Thirty-two cats are currently asymptomatic, with or without treatment. Eleven cats died or were euthanized. Five cats were lost to follow-up. Ketoconazole likely is more suppressive than curative because relapses were common after discontinuing therapy. 相似文献
77.
1118 Friesian cows and 101 Friesian heifers were investigated in internal pelvic measurements and their relationships to external measurements. The mean of the pelvic vertical and the medium diagonally diameter of the pelvis are 19.8 cm and 18.3 cm. 363.9 square centimetres and 76.3 centimetres were found for the pelvic surface and pelvic circumference. The difference between the biggest and smallest pelvis was 295.0 square centimetres. Medium to high coefficiences of correlation were detected between the internal pelvic measurements but relationships between internal and external pelvic measurements were low. From determined external pelvic measurements only the hip breadth provides usefull informations of the pelvic shape. 相似文献
78.
M Washizu K Kobayashi K Misaka T Hayashi G Kinoshita M Kondo S Aoki H Orima T Washizu 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1992,54(5):1051-1053
A 2-year-old female Japanese domestic cat weighing 3.6 kg was presented due to marked abdominal distention and was diagnosed as hepatic cyst. The bile acid concentration of the hepatic cyst was as low as the serum bile acid concentration. The membrane of the cysts was excised from the edge of the compressed hepatic tissue and no other surgical manipulation was performed. This surgical procedure is simple and quick compared to hepatic lobectomy, however, it is necessary to evaluate the fluid of the cyst before performing this procedure. 相似文献
79.
L G Rickard G L Zimmerman E P Hoberg P W Lockwood D W Weber R Miller 《Veterinary parasitology》1989,33(2):125-133
The effectiveness of the morantel sustained release trilaminate (MSRT) in controlling gastrointestinal nematodes through a grazing season was evaluated using 60 yearling beef stocker calves randomly divided into 2 groups of 30 animals each. In April 1985, the calves comprising the treatment group each received an MSRT designed to release morantel tartrate continuously for 90 days while those of the control group remained unmedicated. All animals were weighed and samples of rectal feces were taken at 14-day intervals, beginning on Day 0, until trial termination (Day 168). At trial termination, 10 control and 10 treated calves were necropsied for recovery of gastrointestinal nematodes. Three sets of parasite-na?ve tracer calves were utilized to evaluate the initial, interim and final levels of pasture contamination by nematode larvae. Overall, the use of the MSRT resulted in a 75.5% reduction (P less than 0.001) in output of nematode eggs from the principals, an 81.8% reduction (P less than 0.001) in numbers of gastrointestinal nematodes in principals (at trial termination), and a 96.9% reduction (P less than 0.05) of pasture larval nematode contamination (as indirectly indicated by parasite burdens in tracer calves). The mean weight advantage of treated calves was 16.6 kg per head (P less than 0.001). 相似文献
80.
The administration of 20 mg/kg of acetylsalicylic acid in 18 clinically healthy dogs resulted in a thrombocytopathy with lengthened capillary bleeding time and irreversible aggregation inhibition. Through the set up of individual dilution series, one could conclude the proportional percentage of aggregation functional transfused thrombocytes. The capillary bleeding time was shortened after the intravenous injection of prednisolone (5 mg/kg) without measurable influence on the thrombocytes. Compared to the singular use of cortisone or blood transfusion alone, the effect on capillary bleeding time became magnified when one combined transfusion and corticosteroids. The fresh blood conserves (12 hours) were, with respect to the haemostyptical properties, superior to blood stored for 5 days. The component of aggregation-functional thrombocytes was, due to the prophylactic cortisone application prior to transfusion, not increased. 相似文献