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101.
马尾松木荷混交林林分结构和土壤肥力研究 总被引:10,自引:0,他引:10
对马尾松木荷混交林与马尾松纯林林分生长、径阶分布及土壤理化性质研究表明 :马尾松与木荷以 2∶1比例行状混交 ,马尾松生长快 ,林分各径阶呈正态分布 ,林分生产力高、结构稳定。马尾松木荷混交林不仅提高土壤通透性和蓄水性 ,促进土壤良好结构形成 ,而且增加土壤养分含量 ,改善土壤肥力状况 相似文献
102.
103.
黄山松抚育间伐强度效应试验 总被引:1,自引:4,他引:1
在19年生黄山松林中进行间伐强度效应试验,结果表明:强度间伐对胸径和单株材积生长效应最佳;不同间伐强度对树高生长和林分总收获量无显著影响。 相似文献
104.
105.
不同强度人为干扰15a后,经解析木分析表明,轻度干扰林分中马尾松的胸径、树高、材积均保持良好的生长趋势,总生长量比中度干扰和重度干扰林分高,连年生长量和平均生长量在幼龄期也高于后二者,重度干扰林分的各要素生长量均增长缓慢。这些结果表明超过一定限度的人为干扰阻碍了林木的生长发育。 相似文献
106.
Harrington Timothy B. Minogue Patrick J. Lauer Dwight K. Ezell Andrew W. 《New Forests》1998,15(1):89-106
Eight herbicide combinations containing imazapyr alone or in mixture with glyphosate, triclopyr, or picloram+2,4-D were applied July–August 1991 at each of three upland sites in the southeastern U.S., with or without a subsequent broadcast burn in September. Seedlings of loblolly (Pinus taeda L.) or slash (P. elliottii Engelm. var. elliottii) pine were planted that winter. Second-year (August 1993) vegetation responses indicate that broadcast burning, in combination with herbicides, was associated with increased abundances of grasses, forbs, and shrubs and decreased abundances of vines and hardwood trees. In the presence of burning, imazapyr-in-mixture treatments were associated with a high abundance of grass (53% cover) and a mean size of pines less than that of seedlings growing in imazapyr-alone treatments. In the absence of burning, imazapyr-alone treatments were associated with a high abundance of blackberry (21% cover), an average height of hardwoods (131 cm) exceeding that of pines (71 cm), and a mean size of pines less than that of trees growing in imazapyr-in-mixture treatments. Hardwood height in the absence of burning was less when imazapyr was combined with glyphosate (75 cm) than with triclopyr (102 cm). Regardless of the presence or absence of burning, size of pines and abundance of shrubs and hardwoods did not differ between imazapyr rates of 0.56 and 0.84 kg acid equivalent/ha or among herbicides applied in mixture with imazapyr. 相似文献
107.
108.
美国黄松与秦岭主要松属种叶燃烧性比较 总被引:4,自引:0,他引:4
测定了美国黄松及秦岭松属4种2龄针叶的6个燃烧性因子,并用层次分析的两两比较法分析认为,美国黄松针叶燃烧性差,油松、黑松、白皮松叶燃烧性较强。 相似文献
109.
1998年4月至1999年3月对广州市白云山马尾松林和常绿阔叶林、广州市龙眼洞马尾松林两试验点进行了酸雨的监测,并测定和分析了林内穿透雨物理量及化学量,旨在探讨酸雨对不同森林冠层养分淋溶规律的影响。结果表明:(1)广州市酸雨占次数的79.7%或占降雨量的95.1%。(2)酸雨通过林冠层后,pH值明显增加。(3)在马尾松林和常绿阔叶林中,某些单次降雨出现SO4^2-、NO3^-、NH4^+Al^3+、Na^+的负淋溶现象,说明森林对这些离子(特别是NO3^-、Aa^3+)具有吸收作用;阔叶林全年的NO3^-和Al^3+净淋溶为负值,说明阔叶林比马尾松林对这两种离子具有更强的吸收能力。(4)雨水酸度增加(即pH值减小),明显提高阳离子Ca^2+、Mg^2+、K^+和Na^+冠层淋溶面分率。(5)NH4^+、SO4^ 相似文献
110.
The biomass and the spatial distribution of fine and small roots were studied in two Japanese black pine (Pinus thunbergii Parl.) stands growing on a sandy soil. More biomass of fine and small roots was found in the 17-year-old than in the 40-year-old
stand. There were 62 g m−2 of fine roots and 56 g m−2 of small roots in the older stand, which represented mean values of 608 g for fine and 552 g for small roots per tree, respectively.
In the younger stand, a total of 85 g m−2 of fine roots and 66 g m−2 of small roots were determined, representing a mean of 238 g for fine and 186 g for small roots per tree, respectively. Fine
and small root biomasses decreased linearly with a soil depth of 0–50 cm in the older stand. In the younger stand, the fine
and small roots developed only up to a depth of 30 cm. Horizontal distributions (with regard to distance from a tree) of both
root groups were homogeneous. A positive correlation in the amount of biomass of fine and small roots per m2 relative to tree size was found. Fine and small root biomasses increased consistently from April to July in both stands.
The results also indicated earlier growth activity of the fine roots than small roots at the beginning of the growing season.
The seasonal increases in fine and small root biomasses were slightly higher in the younger stand than the older stand. 相似文献