全文获取类型
收费全文 | 47235篇 |
免费 | 2413篇 |
国内免费 | 4859篇 |
专业分类
林业 | 3858篇 |
农学 | 4730篇 |
基础科学 | 690篇 |
5189篇 | |
综合类 | 22399篇 |
农作物 | 2968篇 |
水产渔业 | 3066篇 |
畜牧兽医 | 6621篇 |
园艺 | 2593篇 |
植物保护 | 2393篇 |
出版年
2024年 | 195篇 |
2023年 | 573篇 |
2022年 | 1104篇 |
2021年 | 1286篇 |
2020年 | 1348篇 |
2019年 | 1620篇 |
2018年 | 1079篇 |
2017年 | 1838篇 |
2016年 | 2334篇 |
2015年 | 2002篇 |
2014年 | 1767篇 |
2013年 | 2408篇 |
2012年 | 3657篇 |
2011年 | 3579篇 |
2010年 | 2802篇 |
2009年 | 2678篇 |
2008年 | 2889篇 |
2007年 | 3383篇 |
2006年 | 3035篇 |
2005年 | 2347篇 |
2004年 | 1956篇 |
2003年 | 1402篇 |
2002年 | 1113篇 |
2001年 | 1017篇 |
2000年 | 962篇 |
1999年 | 807篇 |
1998年 | 661篇 |
1997年 | 577篇 |
1996年 | 575篇 |
1995年 | 566篇 |
1994年 | 476篇 |
1993年 | 478篇 |
1992年 | 441篇 |
1991年 | 377篇 |
1990年 | 334篇 |
1989年 | 244篇 |
1988年 | 197篇 |
1987年 | 115篇 |
1986年 | 118篇 |
1985年 | 54篇 |
1984年 | 26篇 |
1983年 | 14篇 |
1982年 | 6篇 |
1981年 | 11篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1963年 | 5篇 |
1955年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
杉木林地套种绿肥筛选初报 总被引:4,自引:1,他引:3
收集了三十种绿肥,在杉木当年造林地上进行套种试验,根据其生长状况、生物量、覆盖度及对杉木生长的影响,把供试绿肥分成三类,初步筛选出羽扁豆、决明豆、日木草为适宜杉木林地种植的林用绿肥。同时对今后林用绿肥的选择提出了有益的建议。 相似文献
52.
水飞蓟对动物机体免疫功能的影响研究 总被引:2,自引:0,他引:2
将小鼠分为四组,分别饲喂10%水飞蓟、20%水飞蓟、环磷酰胺(0.01g/kg)和空白对照(常规饲料),研究对小鼠免疫功能的影响。实验结果证明,水飞蓟各剂量组能增高小鼠外周血白细胞数目(P<0.01、0.001);提高小鼠腹腔巨噬细胞的吞噬率(P<0.001,0.001)及吞噬指数(P<0.05、0.001)并随剂量加大有增强的趋势;能促进小鼠淋巴细胞转化,提高淋巴细胞转化百分率(P<0.01、0 相似文献
53.
54.
本文报道了江西三种危害食用菌的绿色霉菌的生物学特性。它们是:绿色木霉(Trichoderma Viride pers exFn)。产黄青霉(Penicillium Chrysoenum Thom)和构巢曲霉(Aspergillus nidulcms(Eidzm)Winter)。 相似文献
55.
1959年,将初选出的35个优良家系作进一步的区域性试验,经过4a观测研究后认为.①61号等8个家系,表现突出,在我市推广,增产明显,②选出的17株优树,同初级良种相比,第4年增产138.2%,成熟期可望增产37.7%,③杉木4a生时,进行选择是较为可靠的. 相似文献
56.
The plants of field bean var. Nadwiślaνski were detopped after about 1 month since the beginning of flowering and after that all flower buds were removed from some plants. The effect of a change in the trophic balance on the setting and subsequent growth of root nodules was studied.
The removal of pods had the greater effect on the increase in the weight of the remaining organs than the detopping of plants. Detopping retarded the ageing of the plants and delayed the phase of the greatest reduction of the number of pods. The detopping of plants revealed their considerable compensative possibilities in terms of production of the pod weight and the potential of leaves for biomass production. The data obtained indicate that plant detopping may disturb the root–bacteria exchange of signals, necessary to initiate the nodule development, while the further growth of nodules depends, above all, on the amount of available photosynthates.
A very high correlation between the dry weight of the whole plant to the dry weight of leaves ratio and the weight of nodules was observed. It proves the importance of the trophic balance of the plant for the root nodule weight production. 相似文献
The removal of pods had the greater effect on the increase in the weight of the remaining organs than the detopping of plants. Detopping retarded the ageing of the plants and delayed the phase of the greatest reduction of the number of pods. The detopping of plants revealed their considerable compensative possibilities in terms of production of the pod weight and the potential of leaves for biomass production. The data obtained indicate that plant detopping may disturb the root–bacteria exchange of signals, necessary to initiate the nodule development, while the further growth of nodules depends, above all, on the amount of available photosynthates.
A very high correlation between the dry weight of the whole plant to the dry weight of leaves ratio and the weight of nodules was observed. It proves the importance of the trophic balance of the plant for the root nodule weight production. 相似文献
57.
58.
59.
Matthew A.O. Atilola DVM PhD Joanne R. Cockshutt DVM MS Ron Mclaughlin DVM DVSc Susan M. Cochrane DVM DVSc Paul W. Pennock DVM MS 《Veterinary radiology & ultrasound》1993,34(5):321-324
Five clinically normal five year old dogs were used in this study. From a randomised table inter ver tebral discs were each injected with either collagenase or calcium chloride diluent. The surgically exposed cervical discs were injected with 50 units whereas thoracic and lumbar discs were injected under fluoroscopic guidance with 100 units of the enzyme. Postinjection radiographs revealed significant (p ≤ .05) disc space narrowing in enzyme injected discs. The cervical discs had the highest frequency of radiographic narrowing (87%) followed by the thoracic (70%) and lumbar (53%) discs. Spondylosis deformans developed at the sites of cervical enzyme injections. None of the dogs had neurologic abnormalities one year postinjection. 相似文献
60.