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51.
In a study of fetal cells from a series of 12 pregnancies in ten families at risk for the ultraviolet light-sensitive, DNA repair-deficient diseases xeroderma pigmentosum (XP) and Cockayne syndrome (CS), we detected one XP and two CS homozygote fetuses. The diagnoses were confirmed by analysis of fetal skin fibroblasts or second amniotic samples after termination of the pregnancies. The measurement of ultraviolet light sensitivity and DNA repair depended on properties common to the seven excision repair-deficient XP complementation groups (A-G) and the two CS complementation groups (A, B). No XP variant families were included in the study, because the variant requires different testing techniques. Reliable and rapid diagnosis proved possible in all but one of the 12 pregnancies, supporting the use of these methods until the spectrum of mutations in the various XP and CS genes of the U. S. population is fully characterized and a DNA sequence-based diagnostic procedure becomes available. 相似文献
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紫外线杀菌效能的研究 总被引:8,自引:0,他引:8
自来水的消毒目前普遍采用氯及含氯化合物药剂,消毒过程中产生三卤甲烷等致癌或致突变物质,从而造成水体的二次污染,许多国家已经禁止在消毒中使用含氯药剂。因此,具有安全可靠高效杀菌作用的紫外线消毒技术逐渐发展起来,并越来越受到人们的关注。但是紫外线的使用也有一定的限制,通过紫外线照射时间及进水浊度的变化,研究了具有一定照射强度的紫外灯的杀菌效能变化,并得出了紫外线具有最佳杀菌效果的进水极限浊度和照射时间。同时还研究了紫外线对具有不同抗性的细菌的系灭效率,为饮用水和污水的消毒处理提供了实验基础。 相似文献
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Troy G. Murphy 《Behavioral ecology and sociobiology》2007,61(6):911-918
Both males and females of many avian species maintain elaborate plumage traits, and elaborate monomorphic plumage may convey
adaptive benefits to one or both sexes as inter- or intraspecific signals. Both sexes of the turquoise-browed motmot (Eumomota superciliosa) are elaborately plumed with long racket-tipped tail. I investigated whether the racketed tail functions as a sexually selected
signal in one or both sexes by testing the predictions that males and/or females with the largest tails have: (1) greater
pairing success, (2) greater reproductive performance (clutch-initiation date, clutch size, and hatching success), and (3)
greater reproductive success. Yearling males with longer denuded rachises (wires) on the central tail feathers had greater
pairing success. In addition, adult males with longer wires paired with females who laid larger clutches, had greater hatching
success independent of clutch size, and fledged more young. There was no relationship between female tail plumage and pairing
success, reproductive performance, or fledgling success. These results are consistent with the hypothesis that male tail plumage
functions as a mate choice or status signal, but that the tail of the female does not function in a sexually selected context.
I discuss alternative hypotheses for the evolutionary maintenance of the elaborate female tail plumage. 相似文献
56.
地表水中石油类红外法与紫外法测定结果的比对 总被引:3,自引:1,他引:3
温晓丹 《环境监测管理与技术》2001,13(5):31-33
进行了红外光度法与紫外分光光度法测定混合油样、闽江干流水样和内河水样中石油类的比对试验 ,试验表明 ,两法所测结果相差较大 ,以红外法所得结果较符合水体实际情况 ,提出了红外光度法测定时的注意事项 相似文献
57.
Scytonemin, located in the extracellular polysaccharide sheath of some cyanobacterial species is considered an efficient natural photoprotectant against lethal doses of ultraviolet (UV) radiations. In the present study, scytonemin from the cyanobacterium Rivularia sp. HKAR-4 was partially characterized and investigated for its induction by UV radiation as well as its role in photoprotection. High-performance liquid chromatography (HPLC) with photodiode-array detection studies revealed the presence of an UV-absorbing compound with absorption maximum at 386 nm. Based on its absorption spectrum and ion trap liquid chromatography/mass spectrometry (LC/MS) analysis, the compound was confirmed as scytonemin. In comparison to photosynthetically active radiation, a significant induction in the synthesis of scytonemin was found under UV-stress. Scytonemin also exhibited efficient photoprotective ability by detoxifying the in vivo reactive oxygen species (ROS) generated by UV radiation and by reducing the formation of thymine dimers. To the best of our knowledge this is the first report on the UV-screening effects of scytonemin on in vivo ROS generation and thymine dimer formation in any cyanobacterial strain. Based on these findings, we conclude that scytonemin may play a vital role in the survival and sustainability of cyanobacterial life in adverse environmental conditions such as under high solar irradiances. 相似文献
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Dimer formation was observed during ultraviolet (UV) photolysis of the anti-inflammatory drug diclofenac, and confirmed with mass spectrometry, NMR and fluorescence analysis. The dimers were combinations of the two parent molecules or of the parent and the product of photolysis, and had visible color. Radical formation during UV exposure and dissolved oxygen photosensitized reactions played a role in dimer formation. Singlet oxygen formed via photosensitization by photolysis products of diclofenac. It reacted with diclofenac to form an epoxide which is an intermediate in some dimer formation pathways. Quantum yield of photolysis for diclofenac was 0.21 ± 0.02 and 0.19 ± 0.02 for UV irradiation from medium pressure and low pressure mercury vapor lamps, respectively. Band pass filter experiments revealed that the quantum yield is constant at wavelengths >200 nm. The same dimers formed in laboratory grade water when either of the two UV sources was used. Dimers did not form in wastewater effluent matrix, and diclofenac epoxide molecules may have formed bonds with organic matter rather than each other Implications for the importance of dimer formation in NOM are discussed. 相似文献
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