全文获取类型
收费全文 | 4033篇 |
免费 | 44篇 |
国内免费 | 115篇 |
专业分类
安全科学 | 198篇 |
废物处理 | 273篇 |
环保管理 | 625篇 |
综合类 | 667篇 |
基础理论 | 750篇 |
环境理论 | 1篇 |
污染及防治 | 1186篇 |
评价与监测 | 310篇 |
社会与环境 | 156篇 |
灾害及防治 | 26篇 |
出版年
2023年 | 18篇 |
2022年 | 42篇 |
2021年 | 47篇 |
2020年 | 34篇 |
2019年 | 64篇 |
2018年 | 94篇 |
2017年 | 97篇 |
2016年 | 110篇 |
2015年 | 80篇 |
2014年 | 101篇 |
2013年 | 323篇 |
2012年 | 181篇 |
2011年 | 231篇 |
2010年 | 155篇 |
2009年 | 209篇 |
2008年 | 224篇 |
2007年 | 231篇 |
2006年 | 209篇 |
2005年 | 172篇 |
2004年 | 164篇 |
2003年 | 150篇 |
2002年 | 147篇 |
2001年 | 103篇 |
2000年 | 69篇 |
1999年 | 60篇 |
1998年 | 39篇 |
1997年 | 37篇 |
1996年 | 40篇 |
1995年 | 83篇 |
1994年 | 70篇 |
1993年 | 75篇 |
1992年 | 66篇 |
1991年 | 56篇 |
1990年 | 38篇 |
1989年 | 34篇 |
1988年 | 19篇 |
1987年 | 18篇 |
1986年 | 17篇 |
1985年 | 20篇 |
1984年 | 26篇 |
1983年 | 27篇 |
1982年 | 27篇 |
1981年 | 34篇 |
1980年 | 21篇 |
1979年 | 14篇 |
1978年 | 17篇 |
1976年 | 13篇 |
1974年 | 15篇 |
1973年 | 12篇 |
1972年 | 11篇 |
排序方式: 共有4192条查询结果,搜索用时 62 毫秒
971.
Concentrations of V,Cr, Mn,Fe, Ni,Co, Cu,Zn, As and Cd in mesopelagic crustaceans from the North East Atlantic Ocean 总被引:2,自引:0,他引:2
Specimens of oceanic decapods, mysids and euphausiids, collected from the North East Atlantic Ocean during July 1985, were analysed for V, Cr, Mn, Fe, Ni, Co, Cu, Zn, As and Cd. Measurement of the metals was carried out using two techniques: inductively-coupled plasma-source mass spectrometry (ICP-MS) and atomic absorption (AAS). With the exception of the iron data, good agreement was observed between the data from the two techniques. Baseline-metal data are presented for the species measured, along with any effects of animal size on metal concentration. The data presented for oceanic animals from different trophic levels are important in studies of metal fluxes and for the assessment of markers within the food web in the oceans. 相似文献
972.
Data were tabulated and compared for cases involving prenatal diagnostic procedures performed in the 8 years between January 1985 and December 1992. Of a total of 2781 pregnancies, 2546 cases (91·5 per cent) were diagnosed by amniocentesis, and 235 (8·5 per cent) by chorionic villus sampling (CVS). These findings reflect the fact that amniocentesis has taken deep root as the prenatal diagnostic procedure widely acknowledged by society, whereas even the existence of CVS has yet to be generally recognized. Analysis of our clinical and laboratory results and complication rates, however, suggests that CVS is a safe and accurate alternative to amniocentesis which should and can be positively presented to all patients who are candidates for prenatal diagnosis. 相似文献
973.
974.
We report a female infant noted prenatally to have an umbilical cord mass. At birth, a labial strawberry haemangioma was noted. She subsequently developed an abdominal mass which was discovered to be a proliferating haemangioma, continuous with both the labial and the umbilical stump lesions. 相似文献
975.
We report three cases of Turner's syndrome with cystic hygromata, which were diagnosed by routine ultrasound scanning before amniocentesis in the second trimester of pregnancy. Maternal and amniotic level of alpha-fetoprotein were normal. Karyotyping carried out afterwards showed a 45,X karyotype. Our data indicate, that cystic hygromata in Turner's syndrome may coexist with a normal amniotic fluid AFP, thus questioning the theory of leakage from the hygroma. It remains to be investigated if all cases of Turner's syndrome present a cystic hygroma in utero. 相似文献
976.
977.
Carbon Monitoring Costs and their Effect on Incentives to Sequester Carbon through Forestry 总被引:2,自引:1,他引:2
Oscar J. Cacho Russell M. Wise Kenneth G. MacDicken 《Mitigation and Adaptation Strategies for Global Change》2004,9(3):273-293
Technically, forestry projects have thepotential to contribute significantly tothe mitigation of global warming, but manysuch projects may not be economicallyattractive at current estimates of carbon(C) prices. Forest C is, in a sense, a newcommodity that must be measured toacceptable standards for the commodity toexist. This will require that credible Cmeasuring and monitoring procedures be inplace. The amount of sequestered C that canbe claimed by a project is normallyestimated based on sampling a number ofsmall plots, and the precision of thisestimate depends on the number of plotssampled and on the spatial variability ofthe site. Measuring C can be expensive andhence it is important to select anefficient C-monitoring strategy to makeprojects competitive in the C market. Thispaper presents a method to determinewhether a forestry project will benefitfrom C trading, and to find the optimalmanagement strategy in terms of forestcycle length and C-monitoring strategyA model of an Acacia mangiumplantation in southern Sumatra, Indonesiais used to show that forestry projects canbe economically attractive under a range ofconditions, provided that the project islarge enough to absorb fixed costs.Modeling results indicate that between 15and 38 Mg of Certified Emission Reductions(CERs) per hectare can be captured by thesimulated plantation under optimalmanagement, with optimality defined asmaximizing the present value of profitsobtained from timber and C. The optimalcycle length ranged from 12 to 16 years andthe optimal number of sample plots rangedfrom 0 to 30. Costs of C monitoring (inpresent-value terms) were estimated to bebetween 0.45 (Mg C)-1 to 2.11 (MgC)-1 depending on the spatialvariability of biomass, the variable costsof C monitoring and the discount rate. 相似文献
978.
Alessandro Ghidini MD Shari Fallet Jane Robinowitz Charles J. Lockwood Renate Dische Judith Willner 《黑龙江环境通报》1993,13(3):163-169
We report a case of chromosomal mosaicism for monosomy 21 revealed in amniotic fluid cell culture. Ultrasound examination at 19 weeks' gestation showed in utero growth retardation and a complex cardiac malformation. A repeated amniocentesis confirmed the presence of monosomy 21 mosaicism. In view of the sonographically detected fetal abnormalities, termination of pregnancy was elected. 相似文献
979.
Ronald L. Thomas MD 《黑龙江环境通报》1992,12(11):919-923
Cystic hygromas have historically been associated with a grim prognosis when discovered during prenatal sonographic study of the fetus. This same grim prognosis is not observed by the paediatric surgeon who evaluates the neonate or paediatric patient. We present a fetal patient with a massive anterior cystic hygroma discovered in the third trimester prior to 30 weeks. This case and a review of the literature suggest tailoring the prognosis by category when counselling patients: (1) first trimester, normal karyotype-good; (2) first trimester, abnormal karyotype-poor; (3) second trimester and early third-poor to guarded; and (4) mid to late third trimester-good. 相似文献
980.
F. J. Los MD PhD L. Pijpers M. G. J. Jahoda E. S. Sachs A. Reuss A. M. Hagenaars J. W. Wladimiroff 《黑龙江环境通报》1989,9(7):521-526
Volumes of feto-maternal transfusions (FMTs) in transabdominal chorionic villus sampling (TACVS) in the second trimester of pregnancy were calculated from the difference between maternal alpha-fetoprotein (AFP) concentrations before and 1 h after TACVS. In 50 pregnancies, there existed no correlation between FMT volume and the amount of villi collected or the number of TACVS attempts. The expected risk of fetal exsanguination due to very voluminous FMT could not be substantiated. In one case, immunization could have been the cause of hydrops fetalis, although only a volume of 0.15 ml could be calculated. 相似文献