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481.
紫外分光光度法测定水中丁基黄原酸 总被引:5,自引:0,他引:5
根据丁基黄原酸具有在301 nm紫外波长段有最大吸收峰,pH<2时1 min内能够完全被分解,同时该吸收峰消失的特性,采用紫外分光光度(UV)法测定待测水样中丁基黄原酸浓度,并用待测水样作为背景校正,可有效地消除干扰.该方法的检出限为0.006 mg/L、测定上限为12.00 mg/L,实际水样测定的相对标准偏差小于5.76%.利用不同方法对样品进行分析测试,无明显差异.该方法具有线性相关性好、线性范围宽、操作简单准确等特点. 相似文献
482.
纳米TiO2-Ag改性VACF处理氨气研究 总被引:1,自引:0,他引:1
利用浸渍法将纳米TiO2·Ag负载于粘胶基活性炭纤维上进行改性来处理低浓度氨气,扫描电镜观测和能量色散谱分析表明纳米TiO2和Ag均较成功地负载于VACF表面上,改性VACF对氨气脱除性能良好,最大脱除率为93.3%;当Ag*掺杂量为TiO2含量的0.5wt%时氨气脱除率达到最大值;存在最佳相对湿度为55%;在氨气浓度为13~65 mg/m3范围内,浓度越低,脱除效果越好;处理较高浓度氨气可通过增加改性VACF用量;随着反应连续进行,改性VACF稳定性受到影响,但仍具有脱除氨气能力. 相似文献
483.
484.
浸没式膜-生物反应器污泥组分对膜污染的影响 总被引:1,自引:1,他引:0
研究基于中试规模的浸没式膜生物反应器长期运行的基础上,通过改变操作条件和工艺参数系统考察污泥组分对膜污染的影响。试验结果表明,泥龄10 d时,混合液悬浮固体、胶体物质和溶解性物质对膜污染阻力的贡献分别为24.1%、36.1%和39.8%;泥龄20 d时, 混合液悬浮固体、胶体物质和溶解性物质对膜污染阻力的贡献分别为43.9%、32%和24.1%;泥龄40 d时, 混合液悬浮固体、胶体物质和溶解性物质对膜污染阻力的贡献分别为50.6%、27.3%和22.1%。随着泥龄的增加,胶体物质和溶解性物质所形成的阻力之和在总阻力中所占的比例逐渐下降,但仍为膜污染的重要因素。 相似文献
485.
Zhang Z Zhan X Yan L Li M Hu J Wei F 《Environmental science and pollution research international》2009,16(1):79-84
Background, aim, and scope Foraging patches can be described as a nested hierarchy of aggregated resources, implying that study of foraging by wild animals
should be directed across different spatial scales. However, almost all previous research on habitat selection by the giant
panda has concentrated upon one scale. In this research, we carried out a field study to understand foraging patch selection
by giant pandas in winter at both microhabitat and feeding site scales and, for the first time, attempted to understand how
long it would stay at the feeding sites before moving on.
Materials and methods The field survey was conducted from November 2002 to March 2003 at Fengtongzhai Nature Reserve (102°48′–103°00′ E, 30°19′–30°47′
N), Baoxing County of Sichuan Province, China, to collect data in both microhabitat and control plots. The microhabitat plots
were located by fresh feces or foraging traces left by giant pandas, and the control plots were established to reflect the
environment. Within each microhabitat plot, one 1 × 1 m2 plot was centralized at the center of each feeding site, in which numbers of old bamboos and old shoots, including eaten
and uneaten, were counted, respectively.
Results The results showed that winter microhabitats selected by this species were characteristic of gentle slopes and high old-shoot
proportions and that the latter was even higher at feeding sites. Two selection processes, namely, from the environment to
microhabitats and from the latter to feeding sites, were found during this species’ foraging patch utilization. Giant pandas
preferred to eat old shoots to old bamboo at feeding sites in winter and did not leave unless old-shoot density fell to lower
than the average in the environment.
Discussion Both microhabitats and feeding sites selected by giant pandas were characteristic of high old-shoot density, indicating that
the preferred food item had a significant influence upon its foraging patch selection. The preference for gentle slopes by
giant pandas was presumed to save energy in movement or reflect the need to sit and free its fore-limbs to grasp bamboo culms
when feeding but also seemed to be correlated with an easier access to old shoots. The utilization of old shoots at feeding
sites was assumed to help maximize energy or nutrient intake during their foraging.
Conclusions The difference between microhabitat plots and control plots and between microhabitats and feeding sites uncovered a continuous
selection process from the environment via microhabitats to feeding sites. The utilization of old shoots at feeding sites
was parallel to the marginal value theorem. The selection and abandonment of foraging patches by giant pandas was an optimal
behavioral strategy adapted to their peculiar food with high cellulose and low protein.
Recommendations and perspectives Our results uncovered the importance of multiple scales in habitat selection research. To further understand the process of
habitat selection, future research should pay more attention to resolve the question of how to locate foraging patches under
dense bamboo forests by the giant panda, which was traditionally considered to have poor eyesight, although our research has
answered what type of habitats the giant panda prefers and when to leave. 相似文献
486.
负载型混晶相TiO2光催化剂的低温制备及其光催化活性 总被引:1,自引:0,他引:1
以蒙皂石为载体,钛酸四丁酯为前驱物,在较低温度下由溶胶凝胶法制备得到负载型TiO2光催化剂。研究了理论负载量、固定化温度、干燥、焙烧温度对TiO2/蒙皂石复合光催化剂光催化性能的影响。采用XRD分析技术对复合材料进行了表征。结果表明,负载的TiO2以锐钛矿-金红石的混晶相存在。当TiO2理论负载量为15 mmol/g、溶胶反应温度为25℃、干燥温度为70℃时,TiO2/蒙皂石复合光催化剂对偶氮染料光催化反应1 h降解率达93.40%。该制备技术的特点是在省去高温焙烧的条件下,制备出光催化活性高的负载型光催化剂。 相似文献
487.
488.
489.
Though polychlorinated biphenyls (PCBs) have distributed as threats in the environment to human beings for several decades, monitoring of trace level PCBs in-field is still a challenge. As a potential method for monitoring PCBs at trace levels, Raman spectroscopy has been used to detect several PCBs in the laboratory. To facilitate the development of rapid detection of PCBs by Raman spectroscopy, it is essential to investigate the Raman spectra of all PCB congeners. Herein, the stable configurations and vibrational spectra of all the PCB congeners were calculated by Gaussian 03 program package. Based on molecular symmetry, PCBs are classified into seven groups. The structural features and the normal vibration modes for each group are discussed. Taking the C(2)-2 group as an example, the wavenumber ranges of the various normal vibration modes in the Raman spectra of PCBs were analyzed. The accuracy of calculated results was verified by experimental Raman spectra of PCB77 standard. This study can elucidate further information to promote the development of Raman spectroscopy in environmental monitoring. 相似文献
490.