全文获取类型
收费全文 | 13480篇 |
免费 | 651篇 |
国内免费 | 1531篇 |
专业分类
林业 | 1504篇 |
农学 | 2189篇 |
基础科学 | 1447篇 |
2396篇 | |
综合类 | 3750篇 |
农作物 | 709篇 |
水产渔业 | 444篇 |
畜牧兽医 | 1852篇 |
园艺 | 403篇 |
植物保护 | 968篇 |
出版年
2024年 | 12篇 |
2023年 | 127篇 |
2022年 | 367篇 |
2021年 | 590篇 |
2020年 | 557篇 |
2019年 | 502篇 |
2018年 | 362篇 |
2017年 | 454篇 |
2016年 | 523篇 |
2015年 | 615篇 |
2014年 | 587篇 |
2013年 | 670篇 |
2012年 | 853篇 |
2011年 | 964篇 |
2010年 | 902篇 |
2009年 | 807篇 |
2008年 | 747篇 |
2007年 | 768篇 |
2006年 | 719篇 |
2005年 | 629篇 |
2004年 | 329篇 |
2003年 | 261篇 |
2002年 | 218篇 |
2001年 | 226篇 |
2000年 | 270篇 |
1999年 | 388篇 |
1998年 | 306篇 |
1997年 | 294篇 |
1996年 | 257篇 |
1995年 | 242篇 |
1994年 | 222篇 |
1993年 | 194篇 |
1992年 | 166篇 |
1991年 | 111篇 |
1990年 | 104篇 |
1989年 | 96篇 |
1988年 | 69篇 |
1987年 | 40篇 |
1986年 | 25篇 |
1985年 | 9篇 |
1984年 | 17篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1965年 | 5篇 |
1964年 | 3篇 |
1941年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
马耘秀 《山西农业大学学报(自然科学版)》2014,(1):34-38
对高速公路用地进行集约用地评价,可以为未来区域土地利用提供决策依据。从高速公路的用地结构、用地功能和与外部因素的协调性出发,对山西高速公路建设用地的集约利用程度作出评价。结果表明:2001~2010年,山西省高速公路用地数量有所增长,其结构不断调整,功能不断增强,与人口、社会经济的协调性也不断加强,集约度不断提高。未来10年,山西省高速公路将迅速发展,必须加大集约利用力度,以尽可能少的用地满足人类社会发展对公路交通运输的需求。 相似文献
102.
蕨菜不同生育期对环境条件要求的确定 总被引:1,自引:0,他引:1
蕨菜(Pteridunl aquilinum kuhn)为蕨科蕨属,宿根性草本蕨类植物.生长于山缘、林下和灌木丛中,适应性很强,分布于全国各地,常采集未展叶的叶柄为主要食用器官(即拳卷叶期的蕨菜). 相似文献
103.
为实现对玉米黄花叶病毒(maize yellow mosaic virus,MaYMV)的血清学检测,丰富该病毒的检测方法,将编码MaYMV运动蛋白(movement protein,MP)的基因连接到原核表达载体pDBHis-MBP上,将构建成功的原核表达质粒转化到大肠杆菌Escherichia coli中诱导表达融合蛋白,将纯化后的融合蛋白对新西兰大白兔Oryctolagus cuniculus进行免疫并制备MaYMV MP多克隆抗血清,并采用Western blot对抗血清的效价、灵敏度和特异性进行检测。结果显示,利用成功构建的原核表达载体经诱导表达获得分子量大小约为62 kD的融合蛋白,纯化后对新西兰大白兔进行免疫获得MaYMV MP抗血清,该抗血清的效价为1∶128 000,灵敏度为1∶32,且该抗血清能够特异性地检测到本氏烟Nicotiana benthamiana中瞬时表达的MaYMV MP,而不与马铃薯卷叶病毒属Polerovirus及黄症病毒属Luteovirus的其他病毒发生血清学交叉反应,证明该抗血清具有良好的特异性。表明本研究制备的MaYMV MP抗血清能特异性... 相似文献
104.
The potential drivers in forming avian biodiversity hotspots in the East Himalaya Mountains of Southwest China 总被引:1,自引:0,他引:1 下载免费PDF全文
Little has been published to describe or interpret Asian biodiversity hotspots, including those in the East Himalayan Mountains of Southwest China (HMSC), thus making necessary a review of the current knowledge. The Pliocene and Pleistocene geological and glacial histories of the Asian continent differ from those of Europe and North America, suggesting different mechanisms of speciation and extinction, and, thus, different responses to climate changes during the Quaternary glaciations. This short review summarizes potential drivers in shaping and maintaining high species richness and endemism of birds in the HMSC. The geographical location at the junction of different biogeographical realms, the wide range of habitats and climates along the extensive elevational range, the complex topography and the distinct geological history of this region have probably contributed to the evolution of an exceptionally species‐rich and endemic‐rich, specialized montane avian fauna. The Mountain systems in the HMSC may have provided refugia where species survived during the glacial periods and barriers for preventing species dispersal after the glacial periods. More studies are required to further test this refugia hypothesis by comparing more cold‐tolerent and warm‐tolerent species. 相似文献
105.
Pharmacology of topical prostaglandin F2α analogs and their place in the treatment of glaucoma in small animals 下载免费PDF全文
T. Maślanka 《Journal of veterinary pharmacology and therapeutics》2015,38(2):105-112
A distinguishing feature of the most common types of glaucoma is an increased intra‐ocular pressure (IOP), which has a damaging effect on optic nerve axons, leading to the progressive loss of retinal ganglion cells. Therefore, IOP‐lowering medications are the mainstay of glaucoma therapy. Topical prostaglandin F2α analogs (PGAs) are a relatively new class of ocular hypotensive drugs, which have made a huge impact on the treatment of glaucoma in dogs. This study summarizes the current state of knowledge on the mechanism of action of these agents and their effect on IOP in dogs and cats. It also discusses potential harmful side effects of PGAs and presents contemporary opinions about their role and place in the medical management of glaucoma in small animals. 相似文献
106.
Pharmacokinetics of cefquinome in tilapia (Oreochromis niloticus) after a single intramuscular or intraperitoneal administration 下载免费PDF全文
Q. Shan X. Zhu S. Liu Y. Bai L. Ma Y. Yin G. Zheng 《Journal of veterinary pharmacology and therapeutics》2015,38(6):601-605
The pharmacokinetics of cefquinome was studied in plasma after a single dose (10 mg/kg) of intramuscular (i.m.) or intraperitoneal (i.p.) administration to tilapia (Oreochromis niloticus) in freshwater at 30 °C. Ten fish per sampling point were examined after treatment. The data were fitted to two‐compartment open models following both routes of administration. The estimates of total body clearance (CL/F), volume of distribution (Vd/F), and absorption half‐life (T1/2ka) were 0.049 and 0.037 L/h/kg, 0.41 and 0.33 L/kg, and 0.028 and 0.035 h following i.m. and i.p. administration, respectively. After i.m. injection, the elimination half‐life (T1?2β) was calculated to be 5.81 h, the maximum plasma concentration (Cmax) to be 49.40 μg/mL, the time to peak plasma cefquinome concentration (Tmax) to be 0.14 h, and the area under the plasma concentration–time curve (AUC) to be 204.6 μg h/mL. Following i.p. administration, the corresponding estimates were 6.05 h, 44.39 μg/mL, 0.17 h and 267.8 μg h/mL. The minimum inhibitory concentrations of cefquinome, determined for 30 strains of Streptococcus agalactiae isolated from diseased tilapia, ranged from 0.015 to 0.12 μg/mL. Results from these studies support that 10 mg cefquinome/kg body weight daily could be expected to control tilapia bacterial pathogens inhibited in vitro by a minimal inhibitory concentration value of ≤2 μg/mL. 相似文献
107.
2021年,沂南县推进动物疫病强制免疫“先打后补”工作,依托“鲁牧云”信息平台,通过强化组织领导,加强政策宣贯,强化人员培训,放开强免疫苗经营渠道,提供抗体检测无偿服务等措施,提升了养殖场户“先打后补”的积极性、自主性、灵活性,强化了养殖场户动物防疫主体责任,满足了养殖场户疫苗多样化需求。但由于 “先打后补”补助金额少、社会化服务不规范、基层动物防疫体系弱化、缺少配套工作经费等原因,部分养殖场户实施“先打后补”的积极性不高。建议通过规范社会化服务组织,强化培训水平,提高补助标准,强化三级(县乡村)基础设施建设,升级“鲁牧云”等措施,确保“先打后补”政策惠及更多养殖场户。 相似文献
108.
109.
110.
Tetsuji Ota Tsuyoshi Kajisa Nobuya Mizoue Shigejiro Yoshida Gen Takao Yasumasa Hirata Naoyuki Furuya Takio Sano Raul Ponce-Hernandez Oumer S. Ahmed Heng Sokh Vuthy Ma Eriko Ito Jumpei Toriyama Yukako Monda Hideki Saito Yoshiyuki Kiyono Sophal Chann Nang Ket 《Journal of Forest Research》2015,20(6):484-492