全文获取类型
收费全文 | 51819篇 |
免费 | 2807篇 |
国内免费 | 65篇 |
专业分类
林业 | 2687篇 |
农学 | 1602篇 |
基础科学 | 237篇 |
5896篇 | |
综合类 | 10330篇 |
农作物 | 2016篇 |
水产渔业 | 2446篇 |
畜牧兽医 | 25660篇 |
园艺 | 603篇 |
植物保护 | 3214篇 |
出版年
2019年 | 485篇 |
2018年 | 778篇 |
2017年 | 821篇 |
2016年 | 721篇 |
2015年 | 673篇 |
2014年 | 804篇 |
2013年 | 1813篇 |
2012年 | 1545篇 |
2011年 | 1739篇 |
2010年 | 1109篇 |
2009年 | 1203篇 |
2008年 | 1701篇 |
2007年 | 1687篇 |
2006年 | 1569篇 |
2005年 | 1492篇 |
2004年 | 1409篇 |
2003年 | 1381篇 |
2002年 | 1326篇 |
2001年 | 1560篇 |
2000年 | 1503篇 |
1999年 | 1227篇 |
1998年 | 461篇 |
1997年 | 478篇 |
1996年 | 474篇 |
1995年 | 525篇 |
1994年 | 472篇 |
1993年 | 483篇 |
1992年 | 930篇 |
1991年 | 918篇 |
1990年 | 910篇 |
1989年 | 920篇 |
1988年 | 867篇 |
1987年 | 900篇 |
1986年 | 891篇 |
1985年 | 897篇 |
1984年 | 723篇 |
1983年 | 653篇 |
1979年 | 647篇 |
1978年 | 541篇 |
1977年 | 459篇 |
1976年 | 463篇 |
1975年 | 503篇 |
1974年 | 692篇 |
1973年 | 606篇 |
1972年 | 677篇 |
1971年 | 671篇 |
1970年 | 599篇 |
1969年 | 590篇 |
1968年 | 451篇 |
1967年 | 512篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
G Plassiart J F Guelfi J P Ganiere B Wang G Andre-Fontaine M Wyers 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1992,39(6):443-453
Twenty rabbits were inoculated with a suspension of Viral Hemorrhagic Disease virus. Hemostatic functions were assessed every sixth hour from 6 to 60 hours post-inoculation. Tissue samples obtained at the same intervals allowed the study of the development of lesions throughout the experiment. Biological signs of Disseminated Intravascular Coagulation (DIC) were detected on and after 30 h post-inoculation and consisted of prolonged One Stage Prothrombin Time and Activated Partial Thrombin Time, the decrease of factors V, VII, and X and high levels of soluble fibrin monomer complexes and D-dimers. A reduction of thrombocyte numbers, heterophils and lymphocytes was associated. The close association of DIC and necrotizing hepatitis lesions suggested the hepatic lesions to be the most important DIC triggering factor. Other mechanisms are discussed. 相似文献
22.
A rapid and low cost procedure, the carbon immunoassay (CIA) test, was evaluated for the diagnosis of Toxoplasma gondii infections. Using a closely related parasite (Besnoitia jellisoni) as antigen, and homologous or heterologous immune sera, it was demonstrated by light and electron microscopy that CIA is a very reliable and specific test. As it is neither expensive nor time-consuming, it can be recommended for general and routine laboratory use. 相似文献
23.
In mid-September, 1 month before the insertion of intravaginal pessaries to induce sexual activity, blood samples were collected every 4 days from 16 ewe lambs aged 7 months, in order to determine the incidence of ovulations by measurement of plasma progesterone concentrations. It has been studied whether the response to a progestagen treatment of ewe lambs apparently close to puberty could be modified by the onset of the ovarian events preceding puberty. The effect of the presence or absence of ovulations prior to progestagen treatment on the potential reproductive performance (fertility, litter size and fecundity), embryo development [embryo quality and interferon-tau (IFNτ) secretion], luteal function (progesterone secretion in vitro ) and endometrial progesterone content was studied in seven ovulating (Ov+) and nine nonovulating ewe lambs (Ov−) on day 14 after mating. The best potential reproductive results were obtained with Ov+ animals, although these differences could not be initially attributed to either different progesterone secretion in vitro or concentration of endometrial progesterone. Irrespective of the experimental groups, secretion of progesterone by luteal tissue from ewe lambs with normal embryos was significantly greater (p<0.05) than that of animals with abnormal embryos or with no embryos. Normal embryos secreted a higher amount of IFN-τ than those embryos classified as abnormal (p<0.07). In conclusion, ewe lambs which exhibit luteal activity before puberty have the highest levels of reproductive performances after a progestagen treatment. Corpora lutea from ewe lambs with normal embryos had higher rates of progesterone secretion in vitro and their embryos had a higher IFN-τ production by the embryos, indicating greater capacity for subsequent development. 相似文献
24.
Meat regulations also involve game inspection. This publication deals with the regulations concerning furred game intended for slaughter and furred game hunted for food. 相似文献
25.
Duration of maternal immunity to peste des petits ruminants 总被引:1,自引:0,他引:1
26.
27.
28.
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
29.
30.