全文获取类型
收费全文 | 202篇 |
免费 | 3篇 |
国内免费 | 1篇 |
专业分类
林业 | 9篇 |
农学 | 15篇 |
19篇 | |
综合类 | 37篇 |
农作物 | 6篇 |
水产渔业 | 4篇 |
畜牧兽医 | 106篇 |
园艺 | 4篇 |
植物保护 | 6篇 |
出版年
2023年 | 5篇 |
2022年 | 8篇 |
2021年 | 10篇 |
2020年 | 7篇 |
2019年 | 7篇 |
2018年 | 8篇 |
2017年 | 5篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 10篇 |
2013年 | 10篇 |
2012年 | 6篇 |
2011年 | 15篇 |
2010年 | 8篇 |
2009年 | 7篇 |
2008年 | 3篇 |
2007年 | 4篇 |
2006年 | 6篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 6篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有206条查询结果,搜索用时 15 毫秒
61.
62.
Verminous encephalomyelitis due to Angiostrongylus cantonensis larvae was diagnosed in 2 foals at necropsy. The principal clinical feature was tetraparesis, although history and neurological examination revealed progressive and multifocal neurological disease. At presentation, a tentative diagnosis of parasitic larval migration involving the central nervous system (CNS), presumably due to Strongylus vulgaris, was proposed. Dissection of the spinal cord in one case resulted in recovery of intact larvae of both sexes of A. cantonensis. In both foals, histopathology of the brain and spinal cord revealed nematode sections which were consistent with A. cantonensis larvae. 相似文献
63.
Estimating the mass of asteroid 253 mathilde from tracking data during the NEAR flyby 总被引:1,自引:0,他引:1
DK Yeomans J Barriot DW Dunham RW Farquhar JD Giorgini CE Helfrich AS Konopliv JV McAdams JK Miller WM Owen DJ Scheeres SP Synnott BG Williams 《Science (New York, N.Y.)》1997,278(5346):2106-2109
The terminal navigation of the Near Earth Asteroid Rendezvous (NEAR) spacecraft during its close flyby of asteroid 253 Mathilde involved coordinated efforts to determine the heliocentric orbits of the spacecraft and Mathilde and then to determine the relative trajectory of the spacecraft with respect to Mathilde. The gravitational perturbation of Mathilde on the passing spacecraft was apparent in the spacecraft tracking data. As a result of the accurate targeting achieved, these data could be used to determine Mathilde's mass as 1.033 (+/- 0.044) x 10(20) grams. Coupled with a volume estimate provided by the NEAR imaging team, this mass suggests a low bulk density for Mathilde of 1.3 grams per cubic centimeter. 相似文献
64.
Neodymium (Nd) isotopic data show consistent patterns in the sources of sedimentary rocks in North America at a continental scale. Between 600 and 450 million years ago (Ma), ancient continental shield sources dominated. Around 450 Ma, detritus from the Caledonian-Appalachian mountains overwhelmed sediment from all older sources, and is documented over large areas of the southern, western, and northern margins of North America. This material continued to dominate the sediment supply until about 150 Ma, probably due to cannibalistic recycling of sedimentary rocks formed earlier. Around 150 Ma, the rising western Cordillera delivered new and different detritus to the sedimentary system. 相似文献
65.
High levels of intracellular bombesin characterize human small-cell lung carcinoma 总被引:25,自引:0,他引:25
T W Moody C B Pert A F Gazdar D N Carney J D Minna 《Science (New York, N.Y.)》1981,214(4526):1246-1248
"Small cells" or "oat cells" characterize a virulent form of lung cancer and share many biochemical properties with peptide-secreting neurones. The neuropeptide bombesin is present in all small-cell lines examined, but not in other lung cancer cell lines, suggesting that bombesinergic precursor cells in lung may give rise to this disease. 相似文献
66.
67.
首先,将含有强抗镉czcA基因的重组质粒pGM-T载体进行PCR扩增和鉴定,其次,将带有双酶切位点的czcA基因与pGEX-4T-2载体构建,转化于E.coli BL21 DE3中,最后,经PCR鉴定和测序检测均表明试验成功,为下一步czcA基因片段进行诱导融合蛋白的表达提供了前提。 相似文献
68.
JK Harmon SJ Ostro LAM Benner KD Rosema RF Jurgens R Winkler DK Yeomans D Choate R Cormier JD Giorgini DL Mitchell PW Chodas R Rose D Kelley MA Slade ML Thomas 《Science (New York, N.Y.)》1997,278(5345):1921-1924
Radar observations of comet Hyakutake (C/1996 B2) made at the Goldstone Deep Space Communications Complex in California have detected echoes from the nucleus and from large grains in the inner coma. The nucleus of this bright comet was estimated to be only 2 to 3 kilometers in diameter. Models of the coma echo indicate backscatter from porous, centimeter-size grains ejected anisotropically at velocities of tens of meters per second. The radar observations suggest that a comet's activity may be a poor indicator of its size and provide evidence that large grains constitute an important component of the mass loss from a typical active comet. 相似文献
69.
黑木耳菌糠与牛粪不同配比对堆肥养分性状及发芽指数的影响 总被引:1,自引:0,他引:1
根据黑木耳菌糠与牛粪不同配比下堆肥养分性状及发芽指数(GI)的变化,筛选两种农业废弃物腐解的最佳配比.采取室内培养法,将风干、粉碎的黑木耳菌糠与牛粪按照10︰0、9︰1、7︰3、5︰5、3︰7、1︰9和0︰10共7个比例混合,用(NH4)2SO4溶液调节适宜的含水率(60%)和碳氮比(25︰1),随后接种微生物腐熟剂进行为期90 d的好氧腐解试验,通过堆肥pH、总有机碳(TOC)、总养分(N+P205+K20)、C/N及GI的动态分析,筛选黑木耳菌糠与牛粪堆肥的最佳比例.结果表明:各处理下堆肥的pH、TOC含量及C/N比经90 d腐解后均有不同程度下降,而全氮、全磷、总养分含量及GI值有不同程度的增加.黑木耳菌糠与牛粪按照7︰3混合堆肥后,pH由6.94降至5.83,TOC含量及C/N比分别降低41.0%和71.9%,T值获得最小值(0.28),全氮、全磷、全钾、总养分含量及GI值分别增加109.9%、163.0%、39.7%、124.3%和89.0%.经上述腐熟指标的评价,该比例堆肥的优势明显高于其他处理. 相似文献
70.
Milla Solismaa Sauli Laaksonen Minna Nylund Elisa Pitk?nen Riitta Airakorpi Antti Oksanen 《Acta veterinaria Scandinavica》2008,50(1):20