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951.
基于灰色理论和气象灾害普查资料对黑龙江省暴雨洪涝灾害时空分布特征进行了分析并进行了灾变预测。黑龙江省暴雨洪涝灾害主要发生在5-9月,其中7月损失最大;1990年以来暴雨次数虽然有所减少,但暴雨洪涝造成的损失却明显增加;黑龙江省暴雨洪涝灾害可划分为严重洪涝区、重洪涝区、中洪涝区和轻洪涝区,严重洪涝区位于松花江及其支流沿岸的大庆市、伊春市、齐齐哈尔市、佳木斯市和哈尔滨市。根据灰色灾变预测理论预测2013年出现严重暴雨洪涝灾害(全省农作物受灾面积≥500 000 hm2、可比经济损失≥50 000万元)的可能性最大,其次是2016年。 相似文献
952.
从污水处理厂二沉池分离获得一株硫酸盐还原菌厌氧菌株,依据生理生化分析和16S rDNA基因序列测定该菌株被鉴定为脱硫脱硫弧菌(Desulfovibrio desulfuricans)。在气体吸收的双膜理论和液相中微生物转化的米门方程基础上,建立了搅拌式生物吸收反应器中脱硫脱硫弧菌净化二氧化硫气体的动力学模型,并求解出相应的动力学参数基质转化最大速度Vmax和米氏常数Km,实验结果所得到的线性方程相关性较好,线性相关系数可以达到0.998,而且脱硫脱硫弧菌吸收液具有较高转化二氧化硫的能力。 相似文献
953.
为了进一步推广和发展光伏发电项目,将新兴学科的可拓理论引入光伏发电项目质量评价之中,在物元理论和可拓分析的基础上,构建了光伏发电项目可拓评价指标体系和模型,通过计算各项指标相对于各评价等级的关联度,对待评价项目进行了优劣排序。以3个陕西省2012年光伏发电项目为例,论证了该模型合理可靠,实证结果很好的反映了光伏发电项目的质量,为项目决策提供科学的依据。 相似文献
954.
Bacteria transport and adhesion experiments under water-saturated and partially saturated conditions were examined over a
wide range of ionic strength, from 1 to 100 mM KCl, CaCl2, and MgCl2, and at water contents of 0.15 and 0.22 in sand columns packed with three different sands, baked, sterilized, and raw sands
in order to investigate the effects of ionic strength, water content, and porous media type on the microbial adhesion in soil
aquifer treatment (SAT). Well-characterized Escherichia coli JM109 were used as model bacterial cells in this study. Column study results showed that bacterial deposition rates increased
with increasing ionic strength and decreasing water content, and were higher in raw sand columns than those in other sand
columns. The Derjaguin–Landau–Verwey–Overbeek (DLVO) theory was applied to experimental results in order to consider the interaction
energies between the bacterial cells and collector grains; results revealed that a considerable amount of bacterial cells
was weakly deposited onto the solid surfaces in secondary minimum. 相似文献
955.
渗流场对地铁隧道沉降与受力影响的流固耦合分析 总被引:4,自引:0,他引:4
地下水问题是富水地层地下结构设计与施工中普遍存在的问题。为探讨地下水流动对软岩地铁隧道的稳定性及衬砌支护受力的影响,根据流固耦合理论,采用三维快速拉格朗日有限差分方法,在不同地下水位及排水边界条件下,对开挖后洞室周边场地位移、应力场、孔隙水压力的分布情况进行了综合分析。结果显示,由渗流引起的渗透力一定程度上会增加隧道周边场地变形及衬砌应力。从围岩-支护结构共同作用的原理出发,验证了隧道开挖与支护结构设计时需要考虑渗流效应,反映了地下水确实对隧道稳定性有着重要影响。 相似文献
956.
人因失误与人不安全行为相关原理的分析与探讨 总被引:8,自引:5,他引:3
从人因失误的机理、分类和特点等方面,对人因失误与人不安全行为间的相关原理进行系统的对比分析与探讨,笔者认为,应从安全教育、技术培训、人机系统设计等方面预防人因失误,从建立和维持操作者对安全工作的兴趣、作业标准化、安全管理等方面来控制人的不安全行为。以煤矿斜井提升事故为例,说明人因失误与人不安全行为的判定原则和方法,从而为预防、控制人因事故提供理论依据。 相似文献
957.
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959.
Juan-Camilo Cardenas 《Environment, Development and Sustainability》2000,2(3-4):305-322
The use of experimental settings to observe human behaviour in a controlled environment of incentives, rules and institutions, has been widely used by the behavioural sciences for sometime now, particularly by psychology and economics. In most cases the subjects are college students recruited for one to two hour decision making exercises in which, depending on their choices, they earn cash averaging US$ 20. In such exercises players face a set of feasible actions, rules and incentives (payoffs) involving different forms of social exchange with other people, and that in most cases involve some kind of externalities with incomplete contracts, such as in the case of common-pool resources situations. Depending on the ecological and institutional settings, the resource users face a set of feasible levels of extraction, a set of rules regarding the control or monitoring of individual use, and sometimes ways of imposing material or non-material costs or rewards to those breaking or following the rules. We brought the experimental lab to the field and invited about two hundred users of natural resources in three Colombian rural villages to participate in such decision making exercises and through these and other research instruments we learned about the ways they solve - or fail to - tragedies of the commons with different social institutions. Further, bringing the lab to the field allowed us to explore some of the limitations of existing models about human behaviour and its consequences for designing policies for conserving ecosystems and improving social welfare. 相似文献
960.
Wind selectivity of migratory flight departures in birds 总被引:5,自引:0,他引:5
Optimal migration theory predicts that birds minimizing the overall time of migration should adjust stopover duration with
respect to the rate of fuel accumulation. Recent theoretical developments also take into account the wind situation and predict
that there is a time window (a set of days) during which birds should depart when assisted by winds but will not do so if
there are head winds. There is also a final day when birds will depart irrespective of wind conditions. Hence, the wind model
of optimal migration theory predicts that birds should be sensitive to winds and that there should be a correlation between
departures and winds blowing towards the intended migration direction. We tested this assumption by tracking the departures
of radio-tagged passerines during autumn migration in southern Sweden. Our birds were moderately to very fat when released
and therefore energetically ready for departure. There was a significant correlation between direction of departure and wind
direction. We also found that during days when birds departed there was a significantly larger tail wind component than during
days when birds were present but did not depart. Our results show that passerines do take the current wind situation into
account when departing on migratory flights. We also briefly discuss possible clues that birds use when estimating wind direction
and strength. The inclusion of wind is an important amendment to optimal migration theory of birds and should be explored
further.
Received: 1 March 1999 / Received in revised form: 4 October 1999 / Accepted: 16 October 1999 相似文献