全文获取类型
收费全文 | 125500篇 |
免费 | 6445篇 |
国内免费 | 12662篇 |
专业分类
林业 | 12574篇 |
农学 | 14253篇 |
基础科学 | 8867篇 |
17084篇 | |
综合类 | 48386篇 |
农作物 | 7425篇 |
水产渔业 | 4767篇 |
畜牧兽医 | 17812篇 |
园艺 | 6351篇 |
植物保护 | 7088篇 |
出版年
2024年 | 599篇 |
2023年 | 1788篇 |
2022年 | 4174篇 |
2021年 | 5096篇 |
2020年 | 4581篇 |
2019年 | 4612篇 |
2018年 | 3275篇 |
2017年 | 4881篇 |
2016年 | 4047篇 |
2015年 | 5839篇 |
2014年 | 5952篇 |
2013年 | 6903篇 |
2012年 | 9135篇 |
2011年 | 9455篇 |
2010年 | 9190篇 |
2009年 | 8454篇 |
2008年 | 8078篇 |
2007年 | 7874篇 |
2006年 | 7130篇 |
2005年 | 6056篇 |
2004年 | 3222篇 |
2003年 | 2659篇 |
2002年 | 2449篇 |
2001年 | 2428篇 |
2000年 | 2385篇 |
1999年 | 2191篇 |
1998年 | 1747篇 |
1997年 | 1562篇 |
1996年 | 1417篇 |
1995年 | 1277篇 |
1994年 | 1089篇 |
1993年 | 1129篇 |
1992年 | 887篇 |
1991年 | 746篇 |
1990年 | 627篇 |
1989年 | 502篇 |
1988年 | 385篇 |
1987年 | 236篇 |
1986年 | 136篇 |
1985年 | 69篇 |
1984年 | 45篇 |
1983年 | 40篇 |
1982年 | 50篇 |
1981年 | 49篇 |
1980年 | 32篇 |
1979年 | 14篇 |
1965年 | 15篇 |
1964年 | 11篇 |
1963年 | 12篇 |
1956年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
Pharmacokinetics of xylazine after 2-, 4-, and 6-hr durations of continuous rate infusions in horses
Klaus Hopster Lawrence R. Soma Xiaoqing Li Charlotte Hopster-Iversen Raymond C. Boston Bernd Driessen 《Journal of veterinary pharmacology and therapeutics》2020,43(6):557-564
Intravenous (i.v.) bolus administration of xylazine (XYL) (0.5 mg/kg) immediately followed by a continuous rate infusion (CRI) of 1 mg kg−1 hr−1 for 2, 4, and 6 hr produced immediate sedation, which lasted throughout the duration of the CRI. Heart rate decreased and blood pressure increased significantly (p > .05) in all horses during the first 15 min of infusion, both returned to and then remained at baseline during the duration of the infusion. Compartmental models were used to investigate the pharmacokinetics of XYL administration. Plasma concentration–time curves following bolus and CRI were best described by a one-compartment model. No differences were found between pharmacokinetic estimates of the CRIs for the fractional elimination rate constant (Ke), half-life (t1/2e), volume of distribution (Vd), and clearance (Cl). Median and range were 0.42 (0.15–0.97)/hr, 1.68 (0.87–4.52) hr, 5.85 (2.10–19.34) L/kg, and 28.7 (19.6–39.5) ml min−1 kg−1, respectively. Significant differences were seen for area under the curve ( ) (p < .0002) and maximum concentration (Cmax) (p < .04). This indicates that with increasing duration of infusion, XYL may not accumulate in a clinically relevant way and hence no adjustments are required in a longer XYL CRI to maintain a constant level of sedation and a rapid recovery. 相似文献
994.
995.
996.
AIM: In podocytes, autophagy occurs at a high basal level and dysregulated autophagy is associa-ted with a variety of podocytopathies. This paper is to investigate the role of autophagy in sublytic C5b-9-induced podocyte injury. METHODS: Sublytic complement C5b-9 stimulation was used as an in vitro model. Autophagosomes were confirmed using monodansylcadaverine (MDC) staining. Immunoblotting was used to measure the change of autophagy-related markers. Cellular morphological changes were observed by Wright-Giemsa staining. Immunofluorescence staining and confocal microscopy were used to detect the expression and distribution of nephrin. The cell viability was assessed by methylthiazol tetrazolium (MTT) assay. The cell apoptosis was assessed by Annexin V-fluorescein isothiocyanate/PI staining. RESULTS: For ensuring sublytic complement injury, the maximal amounts of anti-podocyte antiserum and 160×-diluted normal human serum were used without inducing cell lysis (defined as >5% LDH release). Sublytic C5b-9 promoted autophagy of podocytes in vitro. The proautophagic effect of sublytic C5b-9 manifested in the form of accumulated MDC-labeled vesicles and enhanced the expression of LC3-Ⅱ. Autophagy inhibitor 3-methyladenosine (3-MA) promoted sublytic C5b-9-induced podocyte morphological abnormalities. Compared with the sublytic C5b-9-injured podocytes, 3-MA exposure further decreased the expression of nephrin. 3-MA enhanced sublytic C5b-9-induced podocyte apoptosis. CONCLUSION: Sublytic C5b-9 attack induces autophagy, which may play a protective role against complement-mediated podocyte injury. 相似文献
997.
对桂林市南溪山公园植物的科属、生活型、观赏特性、时序景观表现等多方面进行了调查,同时分析了该公园园林树木的生长环境和养护管理情况,针对桂林市南溪山公园植物存在的问题,提出了搞好园林树木种植、配置、养护的建议与对策,为桂林地区公园植物资源的开发利用提供参考。 相似文献
998.
指出了住宅建筑的暖通空调能耗占建筑能耗的比重大,较燃煤取暖而言,热泵技术的节能效果显著。从原理特点、适用性、限制条件、土建和设备建设难度和周期、后期管理维护等方面分析了空气、地表(下)水、土壤、太阳能和污水等热泵热源,探讨了住宅建筑热泵热源选择的总的原则。 相似文献
999.
结合工作实际探讨藏书倒架的前期准备工作及倒架时的路线设计、人员组织安排和倒架后的环节完善。以期减轻图书馆人员在倒架工作中的劳动强度和工作量,提高工作效率。 相似文献
1000.