全文获取类型
收费全文 | 142973篇 |
免费 | 7345篇 |
国内免费 | 83篇 |
专业分类
林业 | 6482篇 |
农学 | 4239篇 |
基础科学 | 890篇 |
15996篇 | |
综合类 | 28471篇 |
农作物 | 5700篇 |
水产渔业 | 6408篇 |
畜牧兽医 | 72127篇 |
园艺 | 1645篇 |
植物保护 | 8443篇 |
出版年
2018年 | 1722篇 |
2017年 | 1886篇 |
2016年 | 1761篇 |
2015年 | 1551篇 |
2014年 | 1845篇 |
2013年 | 5200篇 |
2012年 | 3620篇 |
2011年 | 4386篇 |
2010年 | 2866篇 |
2009年 | 2907篇 |
2008年 | 4352篇 |
2007年 | 4120篇 |
2006年 | 3922篇 |
2005年 | 3701篇 |
2004年 | 3746篇 |
2003年 | 3695篇 |
2002年 | 3565篇 |
2001年 | 4333篇 |
2000年 | 4304篇 |
1999年 | 3302篇 |
1998年 | 1404篇 |
1997年 | 1422篇 |
1995年 | 1609篇 |
1994年 | 1501篇 |
1993年 | 1464篇 |
1992年 | 2987篇 |
1991年 | 3157篇 |
1990年 | 3058篇 |
1989年 | 3122篇 |
1988年 | 2852篇 |
1987年 | 2977篇 |
1986年 | 3099篇 |
1985年 | 3022篇 |
1984年 | 2435篇 |
1983年 | 2239篇 |
1982年 | 1483篇 |
1981年 | 1399篇 |
1979年 | 2219篇 |
1978年 | 1822篇 |
1977年 | 1504篇 |
1976年 | 1471篇 |
1975年 | 1549篇 |
1974年 | 2026篇 |
1973年 | 2040篇 |
1972年 | 2051篇 |
1971年 | 1992篇 |
1970年 | 1821篇 |
1969年 | 1713篇 |
1968年 | 1358篇 |
1967年 | 1486篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
A 3‐year‐old Burmese cat was presented with a history of nonresolving crusted and papular lesions of the face and prior treatment with prednisolone. Skin biopsies revealed typical pox lesions with hyperplasia and ulceration of the epidermis and eosinophilic cytoplasmic inclusion bodies in the epidermal cells. In the upper dermis there was prominent diffuse mast cell infiltration and mild neutrophilic and eosinophilic inflammation. Rare cytoplasmic inclusion bodies were also present in swollen endothelial cells of dermal venules, which showed no other degenerative changes. Histological diagnosis was confirmed by electron microscopic evidence of pox virus particles in inclusion bodies of epidermal cells. The lesions resolved within 6 weeks with systemic antibiotic therapy and supportive care. A 2‐year‐old domestic short‐haired cat was presented with multiple disseminated papular and ulcerative pox lesions with central eschar over the entire body. Histologically, large epidermal inclusion bodies (up to 6 μm in diameter) were present. Widespread haemorrhage and vascular wall necrosis was visible in the dermis and subcutis. Some subcutaneous vessels showed neutrophilic vasculitis. In addition to diffuse dermal neutrophilic and eosinophilic inflammation, a lymphohistiocytic panniculitis was also present. The cat died as a result of massive haemorrhage and lymphedema, despite supportive care. Funding: Self‐funded. 相似文献
72.
73.
74.
As anaerobic sampling and culture techniques improved, the documented prevalence of anaerobic bacteria in periodontal disease has increased. The anaerobic bacteria have become more well-known in humans and consequently in dogs, since this species is a major model in periodontal studies. A review of the literature related to anaerobic flora is described. 相似文献
75.
RNA was extracted from single or small groups of ovine ovarian follicles after treatment of ewes with FSH and/or LH. The content of mRNA for the alpha-inhibin and beta A-inhibin subunits was analyzed by hybridization with specific cDNA probes. All ewes were treated with progestin vaginal pessaries to suppress spontaneous preovulatory follicle maturation and ewes were given three intramuscular injections of gonadotropins at 8-hr intervals starting 24 hr prior to collection of ovaries. In experiment I, both Schering-FSH and NIDDK-oFSH-17 (oFSH) significantly increased alpha- and beta A-inhibin mRNA per ewe in 2-5 mm follicles and tended to increase alpha- and beta A-inhibin mRNA in large (greater than 5 mm) follicles. In experiment II, oFSH and NIDDK-oLH-25 (oLH) were administered in a 2X2 factorial arrangement. Separate administration of oFSH or oLH increased (P less than .05) the alpha-inhibin mRNA concentration in large follicles. alpha-inhibin mRNA concentration in 4-5 mm follicles was also increased by oFSH but was decreased by oLH. Concomitant treatment with oFSH and oLH did not change alpha-inhibin mRNA concentrations from those measured in oFSH treated ewes. In experiment II, beta A mRNA concentrations followed a pattern similar to that of alpha A mRNA, but the differences were not statistically significant. We conclude that, in the ewe, exogenous FSH increases the concentration of inhibin mRNA in the whole follicle. The ability of exogenous oLH to alter expression of the inhibin subunit genes may depend upon the stage of follicle maturation. 相似文献
76.
Cellular alterations in level of expression of mRNA encoding for prostaglandin endoperoxide synthase were quantified within ovarian tissues of sheep obtained before, during and after induction of the preovulatory surge of LH and ovulation with LHRH. This was accomplished by isotopic in situ hybridization using a selective cRNA probe to ovine prostaglandin endoperoxide synthase mRNA. A significant elevation in mRNA was detected within the theca interna of the preovulatory follicle at 8, 16 and 24 hr following administration of LHRH. Very close to the time of ovulation (ie., at 24 hr post-LHRH) a marked rise in mRNA was observed in association with epithelial cells covering the apical surface of the follicle. Ovarian cyclooxygenase metabolites of arachidonic acid produced during the ovulatory process in the ewe originate within the thecal layer and germinal epithelium of the follicle destined to ovulate. 相似文献
77.
78.
R. Iori O. Leoni L. Lazzeri G. Mosca S. Palmieri 《Journal of Agronomy and Crop Science》1991,167(2):91-95
Samples of rapeseed from three Italian growing environments (Bologna, Perugia and Palermo) were analysed for glucose content and dry weight of 1000 seeds every three or four days starting from the end of flowering until complete ripening. In addition, the content of oil, soluble and total proteins, glucosinolates and myrosinase activity was determined in samples of mature seeds. The cultivars used were jet Neuf and Lingot (type 0) and Tandem, Jade and Santana (type 00). From the results it emerged that the point of intersection of the two branches of the linear regression plots for different glucose-consumption kinetics found during seed filling, in addition to being strongly affected by the climate of the test environment, is correlated with quantitative and qualitative production, independently of the genotype. 相似文献
79.
80.