全文获取类型
收费全文 | 25627篇 |
免费 | 159篇 |
国内免费 | 128篇 |
专业分类
安全科学 | 366篇 |
废物处理 | 1397篇 |
环保管理 | 3137篇 |
综合类 | 4601篇 |
基础理论 | 6716篇 |
环境理论 | 7篇 |
污染及防治 | 5727篇 |
评价与监测 | 2007篇 |
社会与环境 | 1895篇 |
灾害及防治 | 61篇 |
出版年
2022年 | 117篇 |
2021年 | 143篇 |
2019年 | 126篇 |
2018年 | 1645篇 |
2017年 | 1540篇 |
2016年 | 1473篇 |
2015年 | 371篇 |
2014年 | 387篇 |
2013年 | 1134篇 |
2012年 | 872篇 |
2011年 | 1910篇 |
2010年 | 1157篇 |
2009年 | 1117篇 |
2008年 | 1501篇 |
2007年 | 1859篇 |
2006年 | 630篇 |
2005年 | 543篇 |
2004年 | 576篇 |
2003年 | 592篇 |
2002年 | 602篇 |
2001年 | 645篇 |
2000年 | 407篇 |
1999年 | 302篇 |
1998年 | 196篇 |
1997年 | 207篇 |
1996年 | 224篇 |
1995年 | 235篇 |
1994年 | 234篇 |
1993年 | 220篇 |
1992年 | 197篇 |
1991年 | 208篇 |
1990年 | 197篇 |
1989年 | 170篇 |
1988年 | 169篇 |
1987年 | 159篇 |
1986年 | 155篇 |
1985年 | 151篇 |
1984年 | 182篇 |
1983年 | 179篇 |
1982年 | 177篇 |
1981年 | 149篇 |
1980年 | 133篇 |
1979年 | 125篇 |
1978年 | 134篇 |
1977年 | 116篇 |
1976年 | 104篇 |
1975年 | 108篇 |
1974年 | 119篇 |
1971年 | 98篇 |
1967年 | 101篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
921.
922.
Galerucella placida Baly (Coleoptera: Chrysomelidae) is a potential biocontrol agent of the rice-field weed Polygonum orientale L. (Polygonaceae). The volatile organic compound (VOC) profiles from undamaged and mechanically damaged plants, and from plants 12- and 36-h following continuous feeding of female G. placida adults and 2nd instar larvae were identified and quantified by GC–MS and GC-FID analyses. Twenty-four and 21 compounds were identified in volatiles of undamaged and insect feeding plants, respectively; whereas 22 compounds were detected in volatiles of mechanically damaged plants. Decanal and 1-dodecanol were unique to undamaged plants, and linalool was detected in volatiles of undamaged and mechanically damaged plants, but not in volatiles of insect damaged plants. However, the beetles are not attracted by none of these volatile components, when tested individually in Y-shaped glass tube olfactometer bioassays. In all plants, methyl jasmonate was predominant. 1-Undecanol was the least amount in undamaged plants, and plants 12-h after feeding by G. placida adults and larvae; whereas 1-tridecanol was the least abundant in plants 36-h after feeding by G. placida adults and larvae, and mechanically damaged plants. The beetles showed significant preference to the whole volatile blends from plants 12-h after feeding by larvae and plants 36-h after feeding by either larvae or adults compared to those of undamaged plants. Further, G. placida responded to individual synthetic compounds, 3-hexanol, 1-octen-3-ol, nonanal, and geraniol at 7, 1.38, 3.75 and 4.5 µg/25 µL CH2Cl2, respectively, and provide a basis for attraction of the potential biocontrol agent in the field. 相似文献
923.
Ashraf M. El-Sayed John Revell Alfredo Jiménez-Perez Aimee Harper David M. Suckling 《Chemoecology》2016,26(5):187-193
The currant clearwing Synanthedon tipuliformis (Clerck) (Sesiidae) is a worldwide pest of black currants, Ribes nigrum. This moth has been observed to feed on nectar of inflorescences of Canada thistles, Cirsium arvense (L.) Scop. This work was undertaken to identify floral compound(s) produced by Canada thistles inflorescences that mediate the response of the currant clearwing. Floral volatiles were collected during the day and analysed by coupled gas chromatography/electroantennographic detection (GC/EAD) and gas chromatography/mass spectrometry (GC/MS). Three compounds consistently elicited EAD response from moth antennae and were identified by GC/MS as phenylacetaldehyde, methyl salicylate and dimethyl salicylate. When the compounds were tested individually or in various combinations in field trapping experiments, a 3-component blend attracted the largest number of female and male currant clearwings. Subsequent field trapping experiments were conducted to determine the optimal attraction dose for the ternary blend using three loadings of 1, 10 and 100 mg loaded into a polyethylene sachet. The highest catches were in traps baited with the 100 mg loading. In all trials, males and mated females were caught in significant numbers, while very low numbers of virgin females were found in the traps. In recent years the efficacy of mating disruption against currant clearwing has been reported as declining. The new kairomone blend identified in this study can be used with the sex pheromone to provide an effective control option for this important pest. 相似文献
924.
In mammals, the chemical profiles of individuals are complex and variable mixtures, and animals perceive information based on variation in the overall quality of these mixtures. A variety of compounds potentially involved in chemical communication have been characterized in the urine of different felid species, but little is known about the information content of felid scent marks. In this study, we investigated whether chemical composition of Eurasian lynx Lynx lynx urine was related to sex, reproductive state, and individual identity. We further analysed if elemental sulphur in lynx urine could serve as a dietary cue or as an indicator for the freshness of a scent mark. We collected urine from captive and wild Eurasian lynx, and analysed volatile constituents of urine by means of solid phase microextraction and gas chromatography-mass spectrometry. Our results show that lynx scent profiles contain sex-specific information on reproductive state, as well as individual identity cues. Urine marks are, therefore, well-suited to fulfil a role in reproductive behaviour and social organisation of wild lynx populations. Relative sulphur content was unrelated to time since last feeding, but decreased with age of the urine sample. The influence of diet and body condition on scent profiles should be further investigated by means of experimental studies, and may shed more light on the messages encoded in carnivore scent-marks. 相似文献
925.
926.
927.
928.
929.
930.
Azin Shamaii Manouchehr Omidvari Farhad Hosseinzadeh Lotfi 《Environmental monitoring and assessment》2017,189(1):42
Performance assessment is a critical objective of management systems. As a result of the non-deterministic and qualitative nature of performance indicators, assessments are likely to be influenced by evaluators’ personal judgments. Furthermore, in developing countries, performance assessments by the Health, Safety and Environment (HSE) department are based solely on the number of accidents. A questionnaire is used to conduct the study in one of the largest steel production companies in Iran. With respect to health, safety, and environment, the results revealed that control of disease, fire hazards, and air pollution are of paramount importance, with coefficients of 0.057, 0.062, and 0.054, respectively. Furthermore, health and environment indicators were found to be the most common causes of poor performance. Finally, it was shown that HSE management systems can affect the majority of performance safety indicators in the short run, whereas health and environment indicators require longer periods of time. The objective of this study is to present an HSE-MS unit performance assessment model in steel industries. Moreover, we seek to answer the following question: what are the factors that affect HSE unit system in the steel industry? Also, for each factor, the extent of impact on the performance of the HSE management system in the organization is determined. 相似文献