全文获取类型
收费全文 | 23049篇 |
免费 | 625篇 |
国内免费 | 4835篇 |
专业分类
安全科学 | 975篇 |
废物处理 | 1560篇 |
环保管理 | 2216篇 |
综合类 | 8709篇 |
基础理论 | 5229篇 |
环境理论 | 6篇 |
污染及防治 | 6222篇 |
评价与监测 | 1537篇 |
社会与环境 | 1417篇 |
灾害及防治 | 638篇 |
出版年
2024年 | 10篇 |
2023年 | 244篇 |
2022年 | 664篇 |
2021年 | 579篇 |
2020年 | 433篇 |
2019年 | 422篇 |
2018年 | 1935篇 |
2017年 | 1917篇 |
2016年 | 1720篇 |
2015年 | 882篇 |
2014年 | 1084篇 |
2013年 | 1389篇 |
2012年 | 1578篇 |
2011年 | 2603篇 |
2010年 | 1604篇 |
2009年 | 1517篇 |
2008年 | 1819篇 |
2007年 | 1984篇 |
2006年 | 736篇 |
2005年 | 554篇 |
2004年 | 438篇 |
2003年 | 554篇 |
2002年 | 574篇 |
2001年 | 384篇 |
2000年 | 399篇 |
1999年 | 425篇 |
1998年 | 353篇 |
1997年 | 318篇 |
1996年 | 301篇 |
1995年 | 264篇 |
1994年 | 179篇 |
1993年 | 159篇 |
1992年 | 119篇 |
1991年 | 97篇 |
1990年 | 65篇 |
1989年 | 54篇 |
1988年 | 46篇 |
1987年 | 19篇 |
1986年 | 22篇 |
1985年 | 11篇 |
1984年 | 22篇 |
1983年 | 18篇 |
1982年 | 10篇 |
1981年 | 2篇 |
1935年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 437 毫秒
151.
Volatiles from leaves or bark of nonhost birch (Betula pendula) and Norway spruce (Picea abies) dramatically reduced the attraction of the bark beetle, Pityogenes bidentatus (Coleoptera: Scolytidae), to their aggregation pheromone components (cis-verbenol and grandisol) in the field. In addition, odors from both the needles and bark of the host Scots pine (Pinus sylvestris) similarly inhibited attraction. Monoterpenes of pine and spruce (α-pinene, β-pinene, terpinolene, and 3-carene) as well
as ethanol, chalcogran and some nonhost green leaf alcohols [(Z)-3-hexen-1-ol, (E)-2-hexen-1-ol, and 1-hexanol], also reduced catches. Collections of volatiles from the field-tested plant tissues indicated
they released monoterpenes in amounts similar to the synthetics that inhibited responses. The various plant and insect sources
of these inhibitory compounds indicate that P. bidentatus bark beetles have evolved several strategies to increase their fitness by avoiding nonhost and unsuitable host trees in a
complex olfactory landscape.
Received: 6 June 2000 / Accepted in revised form: 25 September 2000 相似文献
152.
153.
支景波 《安全.健康和环境》2006,6(9):7-7,9
HSE管理体系进行领导层的内部审核时,审核员多有畏难情绪,不知采取哪种方式,具体审核哪些内容.笔者结合实际的审核经验,谈以下几点体会. 相似文献
154.
Liu Zhenyu Yang Fenglin Quan Xie Zhang Xiaohong 《Frontiers of Environmental Science & Engineering in China》2007,1(2):166-171
A QWASI model dependent on temperature is parameterized to describe the long-term fate of persistent organic pollutants (POPs)
in the Liao River. The model parameters, namely fugacity capacity, degradation rate, and transfer coefficient, are profoundly
affected by temperature. This model is used to simulate the fate of γ-hexachlorocyclohexane (γ-HCH) in the lower reaches of the Liao River from 1998 to 2008. Modeling results show that γ-HCH fugacity capacities in air, water, and sediment increase as temperature decreases, and the transfer and transformation
rate coefficients increase as temperature increases. The variations of transfer and transformation parameter D values depend on fugacity capacities, and transfer and transformation coefficients simultaneously. The performance of the
model is evaluated by comparing the predicted and observed concentrations in the water and sediment of the Liao River. The
predicted values agree well with the observed value in the order of magnitude, in most cases within the factor of 3. It is
believed that the model is appropriate for simulating the long term fate of POPs in the Liao River.
Translated from Environmental Science, 2006, 27(1): 121–125 [译自: 环境科学] 相似文献
155.
In angiosperms, archesporial cells in the anther primordium undergo meiosis to form haploid pollen, the sole occupants of anther sacs. Anther sacs are held together by a matrix of parenchyma cells, the connective tissue. Cells of the connective tissue are not known to differentiate. We report the differentiation of parenchyma cells in the connective tissue of two Gordonia species into pollen-like structures (described as pseudopollen), which migrate into the anther sacs before dehiscence. Pollen and pseudopollen were distinguishable by morphology and staining. Pollen were tricolpate to spherical while pseudopollen were less rigid and transparent with a ribbed surface. Both types were different in size, shape, staining and surface architecture. The ratio of the number of pseudopollen to pollen was 1:3. During ontogeny in the connective tissue, neither cell division nor tetrad formation was observed and hence pseudopollen were presumed to be diploid. Only normal pollen germinated on a germination medium. Fixed preparations in time seemed to indicate that pseudopollen migrate from the connective tissue into the anther sac. 相似文献
156.
157.
Atmospheric particulate pollution of Lanzhou using magnetic measurements 总被引:13,自引:0,他引:13
1 IntroductionAtmosphericparticulateisoneofthemainatmosphericpollutantsinChina.Itmaybeharmfulitselfandcanactasacarrieroftoxicmatterswhichmayhaveremarkableimpactsonhumanhealthandatmosphericenvironmentquality.Combustionofcoal,whichstillservesasprimarye… 相似文献
158.
159.
160.
沉淀物和生物中U,Th和226Ra的联合测定 总被引:1,自引:0,他引:1
用放射化学法对U,Th,~(226)Ra等核素进行联合测定,国外已有不少报道,只是所用的分离方法和所测的介质不同而已。我国学者也做过一些这方面的工作。本工作建立了用三正辛胺-二甲苯萃取分离法对沉积物和生物样中U,Th和~(226)Ra的联合测定方法。 二、主要仪器与试剂 相似文献