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71.
数学形态学在木材表面缺陷图像分割后处理中的应用 总被引:1,自引:0,他引:1
介绍了数学形态学的基本思想和运算。针对木材表面缺陷图像分割效果不完善的问题,提出基于数学形态学的图像后处理方法,包括应用数学形态学的填充操作、形态滤波以及形态梯度边缘检测等。经实验验证,应用数学形态学进行图像后处理,增强了木材缺陷图像分割结果的可视性和准确性。 相似文献
72.
胡家笃 《中南林业科技大学学报(自然科学版)》1991,(1)
本文提出了一种轮系分析的系统化方法。这种方法以轮系组成机构符号为基础,直接构造出轮系分析的数学模型,利用现有的计算机程序进行处理。它不仅能处理各种不同轮系的分析问题,还能将同一轮系不同分析问题(如运动学问题,动力学问题和功率问题)的求解一体化、程序化,可作为轮系CAD的基础。 相似文献
73.
对设在湖南、湖北、四川3省共20个县的现有马尾松水土保持林455块样地及30个径流场进行了调查分析.建立了马尾松水土保持林地年径流量和侵蚀模数的预测模型;应用主成分分析方法和判别分析方法,建立了包括乔木生物色、灌木草本生物量、枯落物生物量、剖面总孔隙度和地表总孔隙度的马尾松水土保持林综合功能等级的评价模型;运用结构决定功能原理,结合林分生长、林分生物量、土壤孔隙度、植被截雨量、年径流量和侵蚀模数的预测模型、编制了马尾松水土保持林优良林分的功能计量表. 相似文献
74.
75.
Sun Hong-gang Zhang Jian-guo Duan Ai-guo He Cai-yun 《中国林学(英文版)》2007,9(1):85-94
Growth and yield modeling has a long history in forestry. The methods of measuring the growth of stand basal area have evolved from those developed in the U.S.A. and Germany during the last century. Stand basal area modeling has progressed rapidly since the first widely used model was published by the U.S. Forest Service. Over the years, a variety of models have been developed for predicting the growth and yield of uneven/even-aged stands using stand-level approaches. The modeling methodology has not only moved from an empirical approach to a more ecological process-based approach but also accommodated a variety of techniques such as: 1) simultaneous equation methods, 2) difference models, 3) artificial neural network techniques, 4) linear/nonlinear regres-sion models, and 5) matrix models. Empirical models using statistical methods were developed to reproduce accurately and precisely field observations. In contrast, process models have a shorter history, developed originally as research and education tools with the aim of increasing the understanding of cause and effect relationships. Empirical and process models can be married into hybrid mod-els in which the shortcomings of both component approaches can, to some extent, be overcome. Algebraic difference forms of stand basal area models which consist of stand age, stand density and site quality can fully describe stand growth dynamics. This paper reviews the current literature regarding stand basal area models, discusses the basic types of models and their merits and outlines recent progress in modeling growth and dynamics of stand basal area. Future trends involving algebraic difference forms, good fitting variables and model types into stand basal area modeling strategies are discussed. 相似文献
76.
森林资源连续清查进界木与漏测木确定标准的研究 总被引:1,自引:0,他引:1
对森林资源连续清查中进界木和漏测木传统确定方法进行分析,指出其存在的随意性和缺乏科学性、明确性;提出应用数理统计方法,通过对已往取得数据的分析,制定出科学、合理、明确的标准。并以云南省2002年森林资源连续清查中楚雄州云南松检尺数据对这一方法进行了具体分析。 相似文献
77.
78.
Walter Seidling 《European Journal of Forest Research》2007,126(4):529-544
Crown transparency estimates of Scots pine, Norway spruce, common beech, pedunculate and sessile oak, annually surveyed between
1990 and 2004 within a grid over Germany, provide a suitable response variable to study drought effects on forest trees. Major
climatic factors, available on a monthly basis as plot-specifically interpolated values and parameters of site and stand conditions,
biotic and other relevant factors were used as predictors in different cross- and length-sectional, and longitudinal models.
Stand age is a considerable and most constant driver of crown transparency in all species. Pine, spruce and beech responded—mainly
with a delay of 1 year—with some foliar loss in areas where there was a surplus of temperature after the generally hot and
dry summer of 2003. Parallel time-series analyses delivered species-specific geographic large-scale patterns with delayed
or recent precipitation deficits or temperature surpluses. Even if beech is partly responding in current years with leaf loss
towards precipitation surpluses, defoliation is especially high 1 year after hot summers, partly a result of high seed sets
after such summers. Crown condition of oak responds in dry and warm areas according to the drought stress hypothesis, however,
in cool and wet mountainous ranges oak responds after wet summers with higher defoliation. Longitudinal approaches revealed
for all 4-tree species significant relationships between crown condition and deviations from the long-term means of temperature,
precipitation but also global radiation and wind speed. Results do not always match the drought stress hypothesis, however,
this is not to expect considering the heterogeneous site, stand and climatic conditions across Germany. Complex interactions
of climatic and biotic factors also impede simple relationships. Soil-related clusters reveal higher sensitivity of spruce
and beech towards climatic drought factors on more acid soils with thin humus layers. Also clusters constructed from plot-specific
courses of defoliation reveal groups with rather closer relationships like a group of pine plots in the Oberpfalz, which seems
to be especially sensitive to summer drought. 相似文献
79.
如何以最少的投入扑灭火灾,把火灾损失降至最低限,是非常关键的。对每次火灾后的扑火费用计算和评估有利于指导和优化今后的扑火工作。本文利用parks数学优化模型对相关参数进行了计算并在设定条件下对计算结果作了比较。 相似文献
80.