全文获取类型
收费全文 | 327篇 |
免费 | 15篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 8篇 |
废物处理 | 18篇 |
环保管理 | 53篇 |
综合类 | 58篇 |
基础理论 | 102篇 |
污染及防治 | 57篇 |
评价与监测 | 18篇 |
社会与环境 | 28篇 |
灾害及防治 | 5篇 |
出版年
2023年 | 6篇 |
2022年 | 5篇 |
2021年 | 10篇 |
2020年 | 14篇 |
2019年 | 6篇 |
2018年 | 29篇 |
2017年 | 18篇 |
2016年 | 27篇 |
2015年 | 13篇 |
2014年 | 18篇 |
2013年 | 24篇 |
2012年 | 21篇 |
2011年 | 28篇 |
2010年 | 12篇 |
2009年 | 14篇 |
2008年 | 19篇 |
2007年 | 7篇 |
2006年 | 12篇 |
2005年 | 6篇 |
2004年 | 8篇 |
2003年 | 10篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1985年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有347条查询结果,搜索用时 15 毫秒
141.
Tauhata L Vianna ME de Oliveira AE Ferreira AC Bragança MJ Clain AF de Faria RQ 《Journal of environmental radioactivity》2006,86(3):384-390
The Instituto de Radioprote??o e Dosimetria has been coordinating the National Intercomparison Program (PNI) for 15 years, from 1991 to 2005. The objective is to evaluate the analytical performance of the laboratories in low-level activity concentration radionuclide assays in environmental samples. This work presents an evaluation of PNI data from 42 intercomparison runs, which distributed to 22 Brazilian laboratories 2511 samples evaluating 5768 radionuclide assays involving 32 radionuclides in the period from 1991 to 2004. The laboratory performance was evaluated using the Normalized Standard Deviation used by the U.S. EPA. For comparison aims, the Normalized Deviation, used by BIPM was also applied. Laboratory performance were grouped and evaluated in three periods of 5 years each. The first period shows, an average value of good performance of 71.2%, the second shows an average of 78.6% and the last an average of 82.3%. Performance for each kind of radionuclide is also presented. 相似文献
142.
Molecular characterisation of a prenatally diagnosed 5q15q21.3 deletion and review of the literature
143.
144.
Fetal growth restriction (FGR) is a common complication of pregnancy, associated with higher risk of perinatal mortality and adverse health and developmental outcomes for surviving infants. True FGR relates to a pathological restriction of fetal growth resulting from complex interactions between maternal, placental, fetal, and environmental factors. Early-onset FGR (onset <32 weeks' gestation) is often first suspected at routine mid-trimester sonographic assessment of fetal morphology, or identified as part of the placental syndrome, commonly maternal pre-eclampsia. Prenatal investigations may identify the cause of FGR. Timing of delivery is guided by serial sonographic surveillance of fetal growth and well-being and maternal condition, balancing the risk of stillbirth with the benefits of advancing gestation. This is particularly pertinent to severe early-onset FGR, a leading iatrogenic cause of very preterm birth. Prognosis is largely determined by the severity of FGR and its causes, gestation at birth, and birthweight. Pregnancy termination may be considered. Antenatal care and delivery in a tertiary center, provided by a multi-disciplinary team with expertise in managing high-risk pregnancies, are imperative to optimizing outcomes. 相似文献
145.
Nicole Corsten-Janssen Katelijne Bouman Janouk C. D. Diphoorn Arjen J. Scheper Rianne Kinds Julia el Mecky Hanna Breet Joke B. G. M. Verheij Ron Suijkerbuijk Leonie K. Duin Gwendolyn T. R. Manten Irene M. van Langen Rolf H. Sijmons Birgit Sikkema-Raddatz Helga Westers Cleo C. van Diemen 《黑龙江环境通报》2020,40(10):1300-1309
Objective
Conventional genetic tests (quantitative fluorescent-PCR [QF-PCR] and single nucleotide polymorphism-array) only diagnose ~40% of fetuses showing ultrasound abnormalities. Rapid exome sequencing (rES) may improve this diagnostic yield, but includes challenges such as uncertainties in fetal phenotyping, variant interpretation, incidental unsolicited findings, and rapid turnaround times. In this study, we implemented rES in prenatal care to increase diagnostic yield.Methods
We prospectively studied 55 fetuses. Inclusion criteria were: (a) two or more independent major fetal anomalies, (b) hydrops fetalis or bilateral renal cysts alone, or (c) one major fetal anomaly and a first-degree relative with the same anomaly. In addition to conventional genetic tests, we performed trio rES analysis using a custom virtual gene panel of ~3850 Online Mendelian Inheritance in Man (OMIM) genes.Results
We established a genetic rES-based diagnosis in 8 out of 23 fetuses (35%) without QF-PCR or array abnormalities. Diagnoses included MIRAGE (SAMD9), Zellweger (PEX1), Walker-Warburg (POMGNT1), Noonan (PTNP11), Kabuki (KMT2D), and CHARGE (CHD7) syndrome and two cases of Osteogenesis Imperfecta type 2 (COL1A1). In six cases, rES diagnosis aided perinatal management. The median turnaround time was 14 (range 8-20) days.Conclusion
Implementing rES as a routine test in the prenatal setting is challenging but technically feasible, with a promising diagnostic yield and significant clinical relevance. 相似文献146.
Appearance of the tribosphenic molar in the Late Jurassic (160 Ma) is a crucial innovation for food processing in mammalian evolution. This molar type is characterized by a protocone, a talonid basin and a two-phased chewing cycle, all of which are apomorphic. In this functional study on the teeth of Late Jurassic Dryolestes leiriensis and the living marsupial Monodelphis domestica, we demonstrate that pretribosphenic and tribosphenic molars show fundamental differences of food reduction strategies, representing a shift in dental function during the transition of tribosphenic mammals. By using the Occlusal Fingerprint Analyser (OFA), we simulated the chewing motions of the pretribosphenic Dryolestes that represents an evolutionary precursor condition to such tribosphenic mammals as Monodelphis. Animation of chewing path and detection of collisional contacts between virtual models of teeth suggests that Dryolestes differs from the classical two-phased chewing movement of tribosphenidans, due to the narrowing of the interdental space in cervical (crown–root transition) direction, the inclination angle of the hypoflexid groove, and the unicuspid talonid. The pretribosphenic chewing cycle is equivalent to phase I of the tribosphenic chewing cycle, but the former lacks phase II of the tribosphenic chewing. The new approach can analyze the chewing cycle of the jaw by using polygonal 3D models of tooth surfaces, in a way that is complementary to the electromyography and strain gauge studies of muscle function of living animals. The technique allows alignment and scaling of isolated fossil teeth and utilizes the wear facet orientation and striation of the teeth to reconstruct the chewing path of extinct mammals. 相似文献
147.
New highly fluorinated monodentate and bidentate phosphine oxide compounds of the type {CF(3)(CF(2))(n)CH(2)CH(2)}(3)PO (n = 5, 9) and [{CF(3)(CF(2))(5)CH(2)CH(2)}(2)P(O)CH(2)CH(2)P(O){CH(2)CH(2)(CF(2))(5)CF(3)}] have been prepared. Their ability to extract a number of metals and radionuclides from aqueous solutions into perfluorinated solvents has been established and the extractable species investigated. All extractants extract the metals As(V), Cd(II), Co(II), Cr(VI), Hg(II), Pb(II), and Sn(II) with >75% removal. In addition, the radioisotopes (90)Sr(II), (133)Ba(II), and U(VI) have been investigated, whilst (59)Fe(III) has been used to model the extraction of plutonium. (133)Ba(II) shows a high distribution ratio for monodentate phosphine oxides, whilst for UO(2)(2+) and (59)Fe(III) bidentate phosphine oxides are superior. 相似文献
148.
Julia Elena Serpa 《生态毒理学报》2000,22(3)
咖啡种植、加工和流通既有积极的环境影响也有消极的环境影响.寿命周期分析是可以用来找到缓解这些消极影响的途径的手段之一.一个简单模式的系统化应当有社会经济性质的附加分析加以补充.当提请人们注意与咖啡生产链有关的问题时,即使旨在找到和提出与当地需要相适应的替代办法,也不应当忘记咖啡业给咖啡种植地区以及加工(洗涤、选择、炒制、研磨和掺合)地区带来很多效益. 相似文献
149.
Julia Geppert Chris Stinton Samantha Johnson Aileen Clarke Dimitris Grammatopoulos Sian Taylor-Phillips 《黑龙江环境通报》2020,40(4):454-462
Objective
To evaluate the test accuracy of non-invasive prenatal testing (NIPT) for fetal trisomy 21, 18, and 13 using cell-free (cf) DNA analysis in maternal plasma with microarray quantitation.Method
Systematic review and meta-analysis. Searches in MEDLINE, Pre-MEDLINE, EMBASE, Web of Science, and the Cochrane Library to 09.07.2018.Results
Five studies analyzing 3074 samples, including 187 trisomy 21, 43 trisomy 18, and 19 trisomy 13 cases, were identified. Risk of bias was high in all studies, introduced particularly by exclusions from analysis and by the role of the sponsor. Sensitivity of microarray-based cfDNA testing was 99.5% (95%CI 96.3%-99.9%) for trisomy 21, 97.7% (95%CI 87.9%-99.6%) for trisomy 18, and 100% (95%CI 83.2%-100%) for trisomy 13. Specificity was 100% (95% CI 99.87%-100%) for trisomy 21, 99.97% (95%CI 99.81%-99.99%) for trisomy 18, and 99.97% (95%CI 99.81%-99.99%) for trisomy 13. Pooled test failure rate was 1.1%. A direct comparison of microarray- and sequencing-based cfDNA found equivalent test accuracy.Conclusion
Included studies suggest that NIPT using microarray-based cfDNA testing has high sensitivity and specificity for detecting fetal trisomy 21, 18, and 13. However, the evidence base is small and at high risk of bias. 相似文献150.