全文获取类型
收费全文 | 34758篇 |
免费 | 328篇 |
国内免费 | 331篇 |
专业分类
安全科学 | 976篇 |
废物处理 | 1597篇 |
环保管理 | 4382篇 |
综合类 | 5031篇 |
基础理论 | 9228篇 |
环境理论 | 13篇 |
污染及防治 | 9194篇 |
评价与监测 | 2564篇 |
社会与环境 | 2212篇 |
灾害及防治 | 220篇 |
出版年
2022年 | 330篇 |
2021年 | 320篇 |
2020年 | 235篇 |
2019年 | 290篇 |
2018年 | 525篇 |
2017年 | 554篇 |
2016年 | 834篇 |
2015年 | 617篇 |
2014年 | 965篇 |
2013年 | 2888篇 |
2012年 | 1159篇 |
2011年 | 1550篇 |
2010年 | 1362篇 |
2009年 | 1320篇 |
2008年 | 1499篇 |
2007年 | 1649篇 |
2006年 | 1446篇 |
2005年 | 1186篇 |
2004年 | 1168篇 |
2003年 | 1141篇 |
2002年 | 1109篇 |
2001年 | 1447篇 |
2000年 | 1016篇 |
1999年 | 612篇 |
1998年 | 440篇 |
1997年 | 438篇 |
1996年 | 483篇 |
1995年 | 496篇 |
1994年 | 471篇 |
1993年 | 408篇 |
1992年 | 429篇 |
1991年 | 376篇 |
1990年 | 398篇 |
1989年 | 387篇 |
1988年 | 328篇 |
1987年 | 312篇 |
1986年 | 278篇 |
1985年 | 286篇 |
1984年 | 311篇 |
1983年 | 300篇 |
1982年 | 322篇 |
1981年 | 261篇 |
1980年 | 226篇 |
1979年 | 275篇 |
1978年 | 202篇 |
1977年 | 210篇 |
1976年 | 175篇 |
1975年 | 167篇 |
1974年 | 164篇 |
1973年 | 167篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
741.
Thermal and mechanical properties of poly(lactic Acid) and poly(ethylene/butylene Succinate) blends 总被引:2,自引:0,他引:2
In this study, blends of poly (lactic acid) (PLA) with poly(ethylene/butylene succinate) (Bionolle) have been investigated
for their thermal and mechanical properties as a function of the concentration of Bionolle. Differential scanning calorimetry
(DSC), dynamic mechanical analysis (DMA), and tensile tests were used to characterize the blends. From the results of the
DMA and DSC, it was found that this blend system was not miscible within the compositions studied. DSC results showed that
adding Bionolle aids in crystallization of PLA. It was observed that increasing the Bionolle concentration led to a slight
increase in the strain-at-break of the blends but a decrease in the Young’s modulus and ultimate tensile strength. Biaxially
oriented films showed an increase in tensile strength, modulus, and strain-at-break. 相似文献
742.
Activated carbon, developed from fertilizer waste, has been used for the removal of Hg2+, Cr6+, Pb2+, and Cu2+. Mass transfer kinetic approach has been successfully applied for the determination of various parameters necessary for designing a fixed-bed absorber. Parameters selected are the length of the (PAZ) primary adsorption zone (δ), total time involved for the establishment of primary adsorption zone (tx), mass rate of flow to the absorber (Fm), time for primary adsorption zone to move down its length (tδ), amount of adsorbate adsorbed in PAZ from breakpoint to exhaustion (Ms), fractional capacity (f), time of initial formation of PAZ (tf) and per cent saturation of column at break point. Chemical regeneration has been achieved with 1 M HNO3. 相似文献
743.
744.
Cardiovascular disease has severe consequences for both individual betterment and organizational health. Yet, organization‐based cardiovascular research remains quite limited. This commentary addresses this void by integrating research dating from the famous Hawthorne experiments with current medical science. It then suggests future organizational research on cardiovascular health and recommends use of specific composite cardiovascular measures to advance our understanding of the organizational implications of cardiovascular disease. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
745.
This study meta‐analyzed the relationships between locus of control (LOC) and a wide range of work outcomes. We categorized these outcomes according to three theoretical perspectives: LOC and well‐being, LOC and motivation, and LOC and behavioral orientation. Hypotheses reflecting these three perspectives were proposed and tested. It was found that internal locus was positively associated with favorable work outcomes, such as positive task and social experiences, and greater job motivation. Our findings are discussed in relation to research on core self‐evaluation and the Big Five personality traits. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
746.
747.
Jiří Pšeja Josef Hrnčiřík Jan Kupec Hana Charvátová Petr Hruzík Michael Tupý 《Journal of Polymers and the Environment》2006,14(3):231-237
Biodegradability testing was performed in an aqueous environment under anaerobic conditions after inoculation with digested sludge from municipal wastewater treatment plant. In cross-linking with 1,2:3,4-diepoxybutane in limits 0.8–9.1% weight, biodegradability degree decreased from 76.8 to 62.2%; when 1,2:7,8 diepoxyoctane in quantities 1.1–13.2% weight was used, biodegradability degree dropped more prominently – from 72.3 to 22.8%. There is obviously a direct connection between growing cross-link degree (assessed by so-called fixation index) and decreasing readiness to biodegradation, apparently owing to build-up of a network forming an obstacle to access of micro-organisms and enzymes. 相似文献
748.
749.
Java(Java也是美国加里福尼亚州Sun Microsystems公司的注册商标)正快速成为一种用于加工制造业和系统集成的计算机编程语言。相对于标准C和C^ 计算机语言而言,Java的多功能性和支持众多计算机操作系统和平台的显著特点,使它能在装备有不同计算机平台和控制系统的机械设备上使用提供了最大的方便性。从而提高了木材产品加工过程的安全性。本文就Java软件系统在木材加工和家具加工过程中的应用以及潜在问题进行探讨。 相似文献
750.
T. D. Blackall M. R. Theobald C. Milford K. J. Hargreaves E. Nemitz L. J. Wilson J. Bull P. J. Bacon K. C. Hamer S. Wanless M. A. Sutton 《Water, Air, & Soil Pollution: Focus》2004,4(6):279-285
Ammonia emissions from two contrasting seabird colonies in Scotland were measured, based on the determination of atmospheric concentrations downwind of the colonies. Atmospheric concentrations of ammonia (NH3) across the downwind plume were compared with the inverse application of a Gaussian dispersion model (ID) to calculate the modelled NH3 emission that would generate the measured cross-wind-integrated plume concentration. In parallel, a tracer gas (sulphur hexafluoride, SF6) was released from the colonies with air samples taken to allow determination of SF6 concentrations. On the basis of the known emission rate of SF6, the magnitude of ammonia emissions was estimated by the cross-wind-integrated tracer ratio (TR) of NH3/SF6 concentrations. Coupled with data on annual bird attendance, the measurements indicate annual emissions from the Isle of May and the Bass Rock of 18 and 132 tonnes NH3-N year–1, respectively. The measured NH3 emissions were compared with estimates of seabird nitrogen excretion to estimate the proportion of excreted N that is volatilised as NH3 (FNr). The emission estimates of the two methods compared favourably, giving 4 and 6 kg NH3-N h–1 (FNr = 15%) for the Isle of May for the ID and TR methods, respectively, and 21 and 25 kg NH3-N h–1 (FNr = 50%) for the Bass Rock for the ID and TR methods, respectively. The results provide the first measurement-based estimates to allow regional up scaling of ammonia emissions from seabirds. 相似文献