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941.
考察沸石粉投加对活性污泥增殖及脱氨氮动力学的影响,并根据相关结论探讨了不同泥龄(SRT)条件下沸石粉的生物再生情况。结果表明,曝气池中投加沸石粉可明显提高活性污泥的产率系数和衰减系数。与传统活性污泥法相比,投加沸石粉的试验组稳定运行后,污泥产率系数和衰减系数分别提高12.5%和16.7%;当泥龄≤10 d时,出水氨氮去除率提高10%~37%,继续增加泥龄,氨氮去除率提高不明显。通过对比试验结果的关联性分析,认为在低浓度条件下,沸石中铵离子的解吸速率是沸石生物再生的限制步骤,而且再生速率与泥龄呈正相关对应关系。 相似文献
942.
Rai A Tripathi P Dwivedi S Dubey S Shri M Kumar S Tripathi PK Dave R Kumar A Singh R Adhikari B Bag M Tripathi RD Trivedi PK Chakrabarty D Tuli R 《Chemosphere》2011,82(7):986-995
World wide arsenic (As) contamination of rice has raised much concern as it is the staple crop for millions. Four most commonly cultivated rice cultivars, Triguna, IR-36, PNR-519 and IET-4786, of the West Bengal region were taken for a hydroponic study to examine the effect of arsenate (AsV) and arsenite (AsIII) on growth response, expression of genes and antioxidants vis-à-vis As accumulation. The rice genotypes responded differentially under AsV and AsIII stress in terms of gene expression and antioxidant defences. Some of the transporters were up-regulated in all rice cultivars at lower doses of As species, except IET-4786. Phytochelatin synthase, GST and γ-ECS showed considerable variation in their expression pattern in all genotypes, however in IET-4786 they were generally down-regulated in higher AsIII stress. Similarly, most of antioxidants such as superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), catalase (CAT), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) increased significantly in Triguna, IR-36 and PNR-519 and decreased in IET-4786. Our study suggests that Triguna, IR-36 and PNR-519 are tolerant rice cultivars accumulating higher arsenic; however IET-4786 is susceptible to As-stress and accumulates less arsenic than other cultivars. 相似文献
943.
It has been speculated that maternal phthalate exposure may affect reproductive development in human newborns. However, the mechanism awaits further investigation. The aim is to evaluate the association between maternal phthalate exposure and cord sex steroid hormones in pregnant women and their newborns from the general population. A total of 155 maternal and infant pair were recruited and analyzed. Levels of urinary phthalate metabolites and sex steroid hormones were determined using liquid chromatography/electrospray tandem mass spectrometry (LC-ESI-MS/MS) and radioimmunoassay (RIA), respectively. No significant correlation was found between each steroid hormones and phthalate metabolites for male newborns, except MMP was marginally significantly correlated with E2. After adjusting for maternal age, estradiol (E2) levels in cord serum from male newborns were not correlated with maternal urinary phthalate metabolites. In female newborns, the maternal urinary levels of mono-(2-ethylhexyl) phthalate (MEHP) and mono-(2-ethyl-5-hydroxyhexyl) phthalate (5OH-MEHP) were negatively correlated with the free testosterone (fT) and fT/E2 levels in cord serum with Pearson correlation coefficients ranging between −0.24 and −0.29 (p < 0.05). Additionally, after gestational age was adjusted, the maternal urinary level of DEHP was negatively correlated with the free testosterone (fT) and fT/E2 levels in cord serum. We suggest that maternal exposure to phthalates may affect sex steroid hormones status in fetal and newborn stage. 相似文献
944.
Laurence Roosens Lieven Bervoets Karen Van Campenhout Rosette Van Den Heuvel Adrian Covaci 《Environmental pollution (Barking, Essex : 1987)》2010,158(8):2546-2552
We assessed the exposure of the Flemish population to brominated flame retardants (BFRs) and perfluorinated compounds (PFCs) by analysis of pooled cord blood, adolescent and adult serum, and human milk. Levels of polybrominated diphenyl ethers (PBDEs) in blood (range 1.6-6.5 ng/g lipid weight, lw) and milk (range 2.0-6.4 ng/g lw) agreed with European data. Hexabromocyclododecane ranged between <2.1-5.7 ng/g lw in milk. Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) dominated in blood and ranged between 1 and 171 ng/mL and <0.9-9.5 ng/mL, respectively. Total PFC levels in milk ranged between <0.5-29 ng/mL. A significant increase in PBDE concentrations was detected from newborns (median 2.1) to the adolescents and adults (medians 3.8 and 4.6 ng/g lw, respectively). An identical trend was observed for PFOS, but not for PFOA. We estimated that newborn exposure to BFRs and PFCs occurs predominantly post-natally, whereas placental transfer has a minor impact on the body burden. 相似文献
945.
在体外消化酶模拟条件下,对小麦籽实中Cd,Pb蛋白质结合体的稳定性进行了研究.结果表明:小麦籽实中存在的表观分子量为54.5×103和5.5×103的蛋白质-Cd,Pb结合体,在体外胃蛋白酶和胰蛋白酶消化后,蛋白质结构发生变化.特别是分子量为54.5×103的Cd,Pb-蛋白质结合体不稳定,容易被胰蛋白酶分解,变成分子量为5.5×103的稳定的Cd,Pb-蛋白质结合体或更小的多肽. 相似文献
946.
947.
非致死剂量的四溴双酚A胁迫下蚯蚓的生长和抗氧化防御反应 总被引:1,自引:0,他引:1
以自然土壤为介质,考察赤子爱胜蚓(Eisenia fetida)的生长抑制率、蛋白质含量、超氧化物歧化酶(SOD)活性、谷胱甘肽转移酶(GST)活性等指标,进行了急性(14 d)、亚急性(28 d)暴露下四溴双酚A(tetrabromobisphenol A,TBBPA)非致死剂量胁迫对蚯蚓的生长和抗氧化防御效应研究。结果表明:在急性试验中TBBPA对蚯蚓的生长抑制均存在显著的剂量效应关系,而在亚急性暴露期,400 mg·kg~(-1)时显著抑制蚯蚓的生长(P<0.05);TBBPA对蚯蚓体内蛋白含量影响,在急性试验中各处理间差异不显著(P=0.712),进入亚急性期蛋白质含量在400 mg·kg~(-1)时被显著诱导(P=0.039,P<0.05);TBBPA对蚯蚓SOD酶活性的影响,在急性试验中50 mg·kg~(-1)时被显著诱导(P<0.01),在亚急性试验中400 mg·kg~(-1)时SOD酶活性显著升高(P<0.05);TBBPA对蚯蚓GST酶活性影响,在急性试验中400 mg·kg~(-1)时呈现显著诱导效应(P<0.05),在亚急性期各处理间差异不显著(P=0.428)。蚯蚓生长抑制率、蛋白质含量、体内各生化酶系对TBBPA暴露的时间效应和剂量效应的敏感性存在不同程度差异,应依据污染暴露指标的有效性和敏感性选择多时间段检测和多指标进行土壤安全评价诊断。 相似文献
948.
949.
Potassium bromate (KBrO3) is a widely used food additive, a water disinfection by-product and a known nephrotoxic agent. The effect of KBrO3 on rat blood, especially on the anti-oxidant defense system, was studied in this work. Animals were given a single oral dose of KBrO3 (100 mg/kg body weight) and sacrificed 12, 24, 48, 96 and 168 h after this treatment. Blood was collected from the animals and separated into plasma and erythrocytes. KBrO3 administration resulted in increased lipid peroxidation, protein oxidation, hydrogen peroxide levels and decreased the reduced glutathione content indicating the induction of oxidative stress in blood. Methemoglobin levels and methemoglobin reductase activity were significantly increased while the total anti-oxidant power was greatly reduced upon KBrO3 treatment. Nitric oxide levels were enhanced while vitamin C concentration decreased in KBrO3 treated animals. The activities of major anti-oxidant enzymes were also altered upon KBrO3 treatment. The maximum changes in all these parameters were 48 h after the administration of KBrO3 and then recovery took place. These results show for the first time that KBrO3 induces oxidative stress in blood and impairs the anti-oxidant defense system. Thus impairment in the anti-oxidant power and alterations in the activities of major anti-oxidant enzymes may play an important role in mediating the toxic effects of KBrO3 in the rat blood. The study of such biochemical events in blood will help elucidate the molecular mechanism of action of KBrO3 and also for devising methods to overcome its toxic effects. 相似文献
950.
Agnieszka Hernik Katarzyna GóralczykPaweł Struciński Katarzyna CzajaWojciech Korcz Maria MinorczykJan Krzysztof Ludwicki 《Chemosphere》2013
The purpose of this study was to assess human exposure in the prenatal period to selected PBDEs (BDE-47, BDE-99, BDE-153) and PCBs (CB-77, CB-101, CB-118, CB-126, CB-138, CB-153, CB-170, CB-180) basing on the analysis of these compounds in cord blood. The experimental material consisted of 89 cord blood samples taken from women resident in Warsaw and its vicinity. In over 90% of all tested samples the presence of congeners CB-153, CB-138, CB-180 and BDE-47 was identified. The least frequently found were CB-126 and BDE-153, which were present at relatively low concentration levels. Among all analysed PCBs, the highest average concentrations were found in the case of congeners CB-138 (11.8 ng/g of fat) and CB-153 (43.4 ng/g of fat), whereas the lowest was in the case of CB-170 (0.4 ng/g of fat) and CB-126 (0.1 ng/g of fat). In the case of PBDEs the greatest share in the total concentration was that of the congeners BDE-47 and BDE-99, whereas the smallest share was that of the higher brominated congener BDE-153. These results suggest that human exposure to the examined compounds begins already in the period of intrauterine life. The comparison of our own results with the findings of other authors indicates that the PCBs and PBDEs levels in cord blood of women living in Poland do not differ from the respective concentrations in cord blood of other female inhabitants of Europe. 相似文献