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991.
The availability of public recreational facilities is being threatened by growing demands, limited supplies, and declining
government funding. In response to these pressures, the economic potential of agroforestry for supplementing operating budgets
of public recreational parks is examined in a case study park consisting of 324 hectares. Agroforestry enterprises native
to the area were selected for development on 70 hectares of the site. Linear programming was used to determine the optimum
combinations of 23 agroforestry regimes composed of the following activities: 1) conventional forestry planting, tree density
of 1682 trees/hectare, 2) the selected agroforestry planting with hay, tree density of 1495 trees/hectare, 3) the selected
agroforestry planting with grazing, 4) hay production, and 5) rental of pasture for grazing. The objective function of the
study was to maximize the net present value of the study site subject to land, labor, capital, and minimum annual income constraints.
The preferred optimal regime generated $1782 per hectare from an agroforestry planting configuration of 1495 trees/hectare
with 75 percent hay, 25 percent grazing, and no annual income requirements. Minimum annual income requirements of $2400 and
$4800 were feasible but suboptimal from a net present value criteria. The study found that agroforestry could be used to privatize
selective activities of public recreational parks and thus enable public agencies to provide these facilities more effectively. 相似文献
992.
对印度引进的木豆晚熟品种ICP70 35 ,在怒江六库进行了不同整地方法的造林试验。试验结果表明 :木豆的单株产量以全垦整地方法为最高达 0 0 6 4kg/株 ,打塘整地方法最低为 0 0 38kg/株。通过投入与产出的经济效益分析 ,得出木豆单位面积的经济效益以全垦整地最高为 3773 2 0元 /hm2 ,种植沟整地次之为 2 932 6 0元 /hm2 ,打塘整地最低为 1971 90元 /hm2 。因此 ,在坡度较平缓、土层深厚的地块 ,宜采用全垦整地方法种植木豆 ;在坡度较大的地带 ,为最大程度地减少水土流失 ,宜采用打塘整地方法种植木豆。 相似文献
993.
The dusuns of Central Maluku which improve fallows by planting spice trees such as clove (Syzygium aromaticum syn. Eugenia aromatica), nutmeg (Myristica fragrans), or coconut (Cocos nucifera) and tending spontaneous regeneration, are an example of a species-rich forest garden system in the eastern hemisphere of
the Indonesian archipelago. In this paper we report the influence of site conditions, as slope inclination, soil type, and
soil depth, on species composition, tree species diversity, and stand structure in old dusuns in four villages on Saparua, a small island south of Seram. In addition, we compared the floristic composition and stand
structure of old dusuns with those of primary forest and advanced fallow vegetation (∼15-yr old). Soil conditions, particularly the depth of the
mineral soil layer, and the relief have a major influence on species selection in dusuns. The most common species in old dusuns were absent both in primary forest and forest fallow. Floristic similarity between old dusuns and the unmanaged stands was low. However, in two study villages species richness of old dusuns was similar to that of the primary forest. Old dusuns showed an open structure with an average reduction of basal area by about half compared to the primary forest. Less than
half of all individuals found above 10 cm DBH in old dusuns were planted. Only very few species were exclusively planted. Most species were both planted and emerged from spontaneous
regeneration. The results indicate the important role of spontaneous regeneration in this forest garden system.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
994.
用少量的土实行集约经营,建立高标准人工林,获得大量的用材,而让公益林得以休养生息和发展,是世界许多国家成功的经验。湖南省实施世行贷款林业项目3期,取得了明显成效,但项目实施过程中出现一些不容忽视的问题,文中提出了解决问题的对策和建议。 相似文献
995.
本文通过对理想点法进行分析,认为该法取不同的p值代表决策者对不同目标的偏爱程度;但p值过大模型求解比较困难,故实际应用时p值取较大的值并不现实.为进一步突出决策人对不同目标的偏爱程度,作者对理想点法进行改进,引进了各目标的权重,提出了加权理想点法.与前者比较,它进一步突出了不同目标对决策结果的影响,使决策结果更符合决策者的愿望,便于在生产中实施.通过用该法对山西省千秋沟林场某经营类型进行收获调整,表明用该法进行森林收获调整,到调整期末龄级结构基本达到完全调整林状态,且可将决策者对不同目标的要求落实到合理水平上. 相似文献
996.
本文描述了在林缘草地施用森林重泡沫灭火剂技术,同时介绍了森林重泡沫灭火剂的质量问题,该剂的特点是稳定性好,抗风力强,并一具有良好的附着力,渗透性和抗烧性。 相似文献
997.
998.
杉木间伐小径材材性试验研究 总被引:7,自引:0,他引:7
杉木间伐小径材材性试验结果与成材杉木比较:密度小,晚材率较低,生长较快,吸水性较强;材质为未成熟幼林材种,物理性质较差,力学强度有所降低,作为建筑结构用材时,在设计与施工中必须注意到其强度的降低,采取必要的措施。杉木间伐小径材纤维长度与成材相似,纤维宽度略宽、纤维长宽比值略小,但尚为良好的纤维原料。 相似文献
999.
The success of many intercropping systems in North America is attributable to the generation of a short term return from an agricultural crop during the early, unprofitable years of a longer term crop that is fruit, nuts or wood. This highly-efficient use of land and related profitability are important not only in the development of intercropping systems per se, but also in other applications which have tremendous potential independent of profitability. For example, intercropping can be effectively used during the establishment phases of hardwood plantations where it is essential to have a high level of weed control, the costs of which are often recovered with the agricultural production. Intercropping can also be used to grow trees rapidly and with a form that can be easily integrated into recreational or park situations, or urban fringe areas. In an urban context, intercropping can be used to grow trees in agricultural areas that are likely to be developed where traditional forestry options are not appropriate and the value of younger, thrifty trees may enhance property values far in excess of the cash value of the wood. 相似文献
1000.
金沙江干热河谷上段退耕还林区适宜造林树种筛选结果:甜酸角、山毛豆、苏门答腊金合欢、新银合欢、久树、印度黄檀等适宜在海拔1400m以下地带造林,构树、木豆、坡柳、余甘子、川楝等适宜在海拔1600m以下地带造林,山合欢、黑荆树、墨西哥柏、干香柏等适宜在海拔1400~1600m地带造林。木豆、坡柳、山毛豆等可进行直播造林,山合欢、黑荆树、川楝、苏门答腊金合欢、新银合欢、久树等采用百日容器苗造林,甜酸角、墨西哥柏、干香柏、印度黄檀等采用1年生容器大苗造林效果更好。块状整地(规格40cm×40cm×40cm),施有机肥加一定量的N、P肥作基肥,塘底施放高丙体粉防治白蚁危害,于雨季初期择时取苗造林,造林后应防止种植塘积水。造林苗木选用充分木质化的粗大壮苗;造林后和雨季中、后期及时清除种植塘周围杂草。 相似文献