全文获取类型
收费全文 | 106603篇 |
免费 | 1799篇 |
国内免费 | 3956篇 |
专业分类
安全科学 | 4336篇 |
废物处理 | 4121篇 |
环保管理 | 15539篇 |
综合类 | 25976篇 |
基础理论 | 28849篇 |
环境理论 | 78篇 |
污染及防治 | 21376篇 |
评价与监测 | 6343篇 |
社会与环境 | 4756篇 |
灾害及防治 | 984篇 |
出版年
2022年 | 1183篇 |
2021年 | 1262篇 |
2020年 | 1051篇 |
2019年 | 1190篇 |
2018年 | 1646篇 |
2017年 | 1770篇 |
2016年 | 2692篇 |
2015年 | 2309篇 |
2014年 | 3241篇 |
2013年 | 10096篇 |
2012年 | 3256篇 |
2011年 | 3839篇 |
2010年 | 3969篇 |
2009年 | 4056篇 |
2008年 | 3312篇 |
2007年 | 3211篇 |
2006年 | 3299篇 |
2005年 | 2999篇 |
2004年 | 3236篇 |
2003年 | 3123篇 |
2002年 | 2652篇 |
2001年 | 3157篇 |
2000年 | 2460篇 |
1999年 | 1812篇 |
1998年 | 1567篇 |
1997年 | 1545篇 |
1996年 | 1667篇 |
1995年 | 1729篇 |
1994年 | 1636篇 |
1993年 | 1447篇 |
1992年 | 1432篇 |
1991年 | 1387篇 |
1990年 | 1316篇 |
1989年 | 1288篇 |
1988年 | 1127篇 |
1987年 | 1035篇 |
1986年 | 1020篇 |
1985年 | 1094篇 |
1984年 | 1195篇 |
1983年 | 1200篇 |
1982年 | 1198篇 |
1981年 | 1118篇 |
1980年 | 961篇 |
1979年 | 958篇 |
1978年 | 840篇 |
1977年 | 739篇 |
1976年 | 662篇 |
1974年 | 654篇 |
1973年 | 675篇 |
1972年 | 683篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
建立了便携式顶空/气相色谱-质谱法测定硬质聚氨酯泡沫和组合聚醚中一氟三氯甲烷(CFC-11)、二氟二氯甲烷(CFC-12)、二氟一氯甲烷(HCFC-22)及一氟二氯乙烷(HCFC-141b)的定性分析方法,系统考察了色谱柱、顶空体系、顶空温度和顶空时间对测定结果的影响。结果表明,DB-WAX色谱柱对目标物质的分离效果最好,顶空温度为50℃、顶空时间为10 min条件下,目标物质的检测灵敏度最高。在优化条件下,硬质聚氨酯泡沫取样体积为1 cm3时,4种目标物的方法检出限为0.6~0.8 μg;组合聚醚取样量为10 mg时,4种目标物的方法检出限为0.5~0.6 μg。该方法具有较高的灵敏度,定性准确,适用于实际样品的现场快速定性分析。 相似文献
52.
Russian Journal of Ecology - Analysis of hunting samples of the Kamchatka sable population for 2001–2013 has revealed changes in the reproductive parameters of females over the period from... 相似文献
53.
Russian Journal of Ecology - Abstract—Long-term observations (1968–2019) on the dynamics of infection by the cestode Eubothrium rugosum in the burbot (Lota lota) have been performed in... 相似文献
54.
55.
Melike E. Bildirici 《Natural resources forum》2020,44(4):289-310
In this paper, the life span of hydro and nuclear energy generations and the relationship between hydro and nuclear energy generations, environmental pollution, and economic growth were investigated for Japan covering the period of 1960–2018 by employing the Bathtub-Weibull curve and Markov switching-vector error correcting (MSVEC) method, respectively. According to the Bathtub-Weibull curve analysis, a rising failure rate for nuclear energy was found, indicating that the life of nuclear energy has expired, but a decreasing failure rate for hydroelectric energy has been detected. Then two different MSVEC models were used. The MSVEC method, unlike traditional approaches, determines the relationship between variables under different regimes. The results of MSVEC methods indicate three important points. First, regime-dependent asymmetry and regime changes are crucial for policy recommendations. Second, the shocks to hydropower and nuclear energy generations cause temporary deviations from the long-run growth path in both regimes. Lastly, the increase in hydropower generation leads to a decrease in environmental pollution and an increase in GDP, and an increase in nuclear power generation increases pollution and growth in both regimes. 相似文献
56.
Koebele Elizabeth A. Crow Deserai A. Albright Elizabeth A. 《Environmental management》2020,65(1):1-18
The 17 Sustainable Development Goals (SDGs) underpinned by 169 targets presents national governments with huge challenges for implementation. We developed a proposal for a National Blueprint Framework (NBF) with 24 water-related indicators, centered on SDG 6 (clean water and sanitation for all), each with a specific target. We applied the NBF to 28 EU Member States (EU-28) and conclude that: 相似文献
57.
58.
59.
Drawing from signaling theory, we propose a work passion transfer model where leaders' passion is transmitted to employees through the former's leadership style and is contingent on employees' perceived importance of performance to self-esteem (IPSE). Data from 201 supervisor–employee dyads from the health-care industry show that leaders' harmonious passion led to employees' harmonious passion through charismatic leadership, whereas contingent reward leadership accounted for the transfer of obsessive passion; IPSE did not play a moderating role for either form of passion. Results from a supplementary study further reveal that the link between leadership and employee passion operated through employees' perception of leader passion and that employees' IPSE accentuated for the relationship between perceived leader obsessive passion and employees' obsessive passion. This study advances research in work passion, leadership, and signaling theory and provides important implications for managerial practice. 相似文献
60.
Julie A. Mansfield Yadetsie N. Zaragoza-Rivera John H. Bolte IV 《Traffic injury prevention》2018,19(8):S8-S13
AbstractObjectives: The objective of this study was to determine whether the amount of tension required for proper child restraint system (CRS) installation varies with lower anchor spacing and to determine whether nonexperts can produce adequate tension on wider-than-standard lower anchor configurations.Methods: CRSs were installed by certified child passenger safety technicians (CPSTs; n?=?6 subjects, n?=?72 installations) and nonexperts (n?=?30 subjects, n?=?120 installations) on a mock-up vehicle seat fixture with lower anchors set at 11 (standard), 15, 19, and 23 in. apart from one another. Each CPST installed a rear-facing (RF) infant base, RF convertible, and forward-facing (FF) convertible into each of the 4 spacing configurations in random order. The CPSTs were instructed to tighten the lower connector strap until the tension was exactly at the threshold between passing and failing the 1-in. test. Each nonexpert installed one CRS model into all 4 spacing conditions in random order. Nonexperts were instructed to install the CRS to the best of their ability. The tension produced on the lower connector strap was recorded via load cell in the lower anchor assembly of the vehicle seat. Resultant tension magnitudes were compared across spacing conditions using matched pair t-tests. The CPSTs’ mean 1-in. test threshold values were compared to tensions produced by nonexperts. Installations were visually evaluated for errors and qualitative usability feedback was collected via survey.Results: CPSTs installed the infant base with higher tensions in the 15-, 19-, and 23-in. configurations compared to the standard 11-in. configuration (P = .034, .032, and .003, respectively). The nonexperts installed the infant base with higher tension in the 15- and 23-in. configurations compared to the 11-in. configuration (P = .004 and .026, respectively). The RF convertible and FF convertible installations showed no significant differences in tension among any of the spacing configurations for either group. Only 19% of the nonexperts’ installations were tight enough to pass CPST thresholds, and the pass rate did not vary with respect to lower anchor spacing. In feedback surveys, the nonexpert group did not show a consistent preference for either standard or wider-than-standard lower anchor configurations.Conclusions: The amount of tension required to pass the 1-in. rule did not vary with lower anchor spacing configurations for the RF and FF convertible CRS, but the infant base required more tension in wider anchor configurations. Nonexperts tended to produce less than ideal tension in all configurations, although their tension magnitudes increased for the infant base in wider configurations. 相似文献