全文获取类型
收费全文 | 8891篇 |
免费 | 434篇 |
国内免费 | 73篇 |
专业分类
林业 | 1340篇 |
农学 | 241篇 |
基础科学 | 60篇 |
1487篇 | |
综合类 | 793篇 |
农作物 | 296篇 |
水产渔业 | 466篇 |
畜牧兽医 | 3941篇 |
园艺 | 246篇 |
植物保护 | 528篇 |
出版年
2023年 | 59篇 |
2022年 | 83篇 |
2021年 | 111篇 |
2020年 | 160篇 |
2019年 | 100篇 |
2018年 | 257篇 |
2017年 | 204篇 |
2016年 | 271篇 |
2015年 | 207篇 |
2014年 | 207篇 |
2013年 | 472篇 |
2012年 | 455篇 |
2011年 | 442篇 |
2010年 | 276篇 |
2009年 | 195篇 |
2008年 | 358篇 |
2007年 | 421篇 |
2006年 | 372篇 |
2005年 | 302篇 |
2004年 | 284篇 |
2003年 | 260篇 |
2002年 | 249篇 |
2001年 | 166篇 |
2000年 | 155篇 |
1999年 | 130篇 |
1995年 | 52篇 |
1992年 | 97篇 |
1991年 | 112篇 |
1990年 | 133篇 |
1989年 | 142篇 |
1988年 | 123篇 |
1987年 | 102篇 |
1986年 | 107篇 |
1985年 | 98篇 |
1984年 | 96篇 |
1983年 | 77篇 |
1982年 | 51篇 |
1979年 | 104篇 |
1978年 | 73篇 |
1977年 | 63篇 |
1975年 | 66篇 |
1974年 | 85篇 |
1973年 | 97篇 |
1972年 | 70篇 |
1971年 | 84篇 |
1970年 | 78篇 |
1969年 | 86篇 |
1968年 | 66篇 |
1967年 | 64篇 |
1965年 | 57篇 |
排序方式: 共有9398条查询结果,搜索用时 0 毫秒
1.
Nephrogenic diabetes insipidus is characterized by polyuria, hyposthenuria and compensatory polydipsia. With conventional clinical and laboratory examinations the diagnosis can be established and the differential diagnostic diseases excluded. In order to verify the diagnosis, differentiate the condition from central and nephrogenic diabetes insipidus and rule out psychogenic polydipsia, additional laboratory studies are required: of these, the concentration test, modified Carter-Robbins test and AVP stimulation test are described. 相似文献
2.
A tumor of the third eyelid gland was diagnosed in a 13 year old female Chihuahua. Histopathology of the excised tissue revealed an apocrine adnexoma with squamous metaplasia. The literature regarding prolapse and tumors of the third eyelid gland was reviewed. No case with similar morphology to this tumor was described to our knowledge. 相似文献
3.
H Müller 《Tier?rztliche Praxis》1991,19(6):591-595
Bluetongue virus (BTV), an arthropod-borne virus, is transmitted primarily by biting midges of the genus Culicoides. Some insect species, which might serve as a potential vector, are prevalent in Central Europe. In sheep, bluetongue is acute and mortality is high, whereas in cattle, goats and most wild ruminants the infection is usually clinically inapparent. Viremia is of short duration in sheep, but cattle experience a prolonged viremia and provide a reservoir for the dissemination of BTV. At least 24 different BTV serotypes have been identified. Antigenic variations occur in the polypeptides of the outer viral capsid and the segmented nature of the viral genome provides the potential for evolution of the virus by a mechanism of reassortment. This renders the use of polyvalent vaccines inefficient and emphasizes the significance of import/export restrictions on ruminants from BTV endemic areas. 相似文献
4.
5.
With the help of a new synthetic material follicles and corpora lutea from the ovaries of 80 cows in different stages of the sexual cycle were examined for modifications of their blood vessel architecture. In the theca externa the main artery which runs towards the follicle, separates into arterioles of which capillaries derive in the theca interna, building a basket-like network around the zona granulosa. After ovulation the follicle wall forms characteristic fields. Capillaries grow into the zona granulosa and thus the folds form the lobular structure of the corpus luteum. Capillaries which rise from the ruptured part of the follicle, spread centripetally and together with lutein cells they build up the not lobulated cupola of the corpus luteum. The regression of the corpus luteum starts around the 16th day of the cycle, beginning at the capillary network of the cupola. A contraction of the vessels and a quick decrease of the volume follow. 相似文献
6.
7.
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
8.
There is only limited information on sheep interferon available. Recent publications have reported on: 1. an interferon (IFN) alpha subtype, which is secreted by the fetal trophectoderm into the lumen of the uterus between the 10th and 21st day of gestation. It was therefore named ovine trophoblast protein (oTP-1), and is responsible for signalling pregnancy to the ewe via high affinity receptors in the endometrium. It is thought that oTP-1 acts by directly influencing prostaglandin metabolism. 2. the role of lentivirus-induced interferon (LV-IFN) in the pathogenesis of Maedi/Visna. The results indicate that LV-IFN limits viral replication and therefore contributes to virus persistence and is also responsible for a chronic inflammatory process. 3. the mitogen- or antigen-dependent induction of ovine interferon gamma (IFN gamma) and its characterization. 相似文献
9.
Dr. Paul Münchberg 《Journal of pest science》1949,22(8):116-119
Ohne Zusammenfassung 相似文献
10.
Dr. F. Hüter 《Journal of pest science》1950,23(4):49-51
Ohne Zusammenfassung 相似文献