全文获取类型
收费全文 | 22350篇 |
免费 | 213篇 |
国内免费 | 179篇 |
专业分类
安全科学 | 617篇 |
废物处理 | 951篇 |
环保管理 | 2808篇 |
综合类 | 3149篇 |
基础理论 | 5854篇 |
环境理论 | 9篇 |
污染及防治 | 6635篇 |
评价与监测 | 1507篇 |
社会与环境 | 1072篇 |
灾害及防治 | 140篇 |
出版年
2023年 | 125篇 |
2022年 | 238篇 |
2021年 | 277篇 |
2020年 | 162篇 |
2019年 | 212篇 |
2018年 | 396篇 |
2017年 | 418篇 |
2016年 | 613篇 |
2015年 | 506篇 |
2014年 | 723篇 |
2013年 | 1873篇 |
2012年 | 845篇 |
2011年 | 1063篇 |
2010年 | 792篇 |
2009年 | 863篇 |
2008年 | 1087篇 |
2007年 | 1117篇 |
2006年 | 953篇 |
2005年 | 791篇 |
2004年 | 798篇 |
2003年 | 727篇 |
2002年 | 712篇 |
2001年 | 810篇 |
2000年 | 587篇 |
1999年 | 346篇 |
1998年 | 258篇 |
1997年 | 237篇 |
1996年 | 284篇 |
1995年 | 293篇 |
1994年 | 278篇 |
1993年 | 233篇 |
1992年 | 220篇 |
1991年 | 202篇 |
1990年 | 221篇 |
1989年 | 200篇 |
1988年 | 192篇 |
1987年 | 181篇 |
1986年 | 168篇 |
1985年 | 156篇 |
1984年 | 185篇 |
1983年 | 186篇 |
1982年 | 178篇 |
1981年 | 177篇 |
1980年 | 147篇 |
1979年 | 167篇 |
1978年 | 115篇 |
1977年 | 106篇 |
1975年 | 101篇 |
1973年 | 95篇 |
1972年 | 105篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
851.
Lino J. Alvarez-Vázquez Gerardo Casal Aurea Martínez Miguel E. Vázquez-Méndez 《Environmental Modeling and Assessment》2017,22(4):279-289
In this work, we propose a technique to automatically optimize the monitoring of any distributed indicator (concentration of a substance along a river, blood pressure of a patient over time, etc.) for which a reliable estimate is previously available. From a mathematical point of view, the problem is based on obtaining a reliable estimate of the chosen indicator (e.g., by numerical simulation), and then solving a multi-objective optimization problem (with mixed real and integer variables) whose solution must provide an efficient and satisfactory monitoring strategy. As an illustrative case, we show the steps to follow in order to implement that strategy when designing a system for monitoring water quality in a river. Finally, we present and analyze the results when applying the proposed technique to study a real case in the Neuse River (North Carolina, USA). 相似文献
852.
853.
This paper investigates the current treatment of environmental issues by two companies within the large made-to-order sector. Fifty questionnaires were issued to the design team of each company to assess current practice in the integration of environmental issues with design activities, awareness of environmental issues, awareness of existing environmental design tools and the preferred format for a potential clean design tool. 相似文献
854.
Ants have a well developed olfactory sense, which they need both for the perception of environmental chemicals, and for a
highly sophisticated intraspecific communication system based on pheromones. The question arises therefore as to how different
odors are coded in the antennal lobe, the first central neuropil to process olfactory information. We measured odor-evoked
activity patterns using in vivo neuropil calcium recording in the antennal lobe of the ant Camponotus rufipes. We found that (a) odors elicit focal activity spots (diameter ca. 20 μm) which most probably represent the olfactory glomeruli;
(b) different odors are coded in odor specific patterns of such activated spots, and a particular spot can participate in
the pattern for different odors; (c) calcium increased in the activated spots within the 2-s stimulation period and slowly
declined thereafter.
Received: 10 March 1999 / Accepted in revised form: 5 July 1999 相似文献
855.
R. G. Tiessen A. M. W. van Elsacker-Niele Chr. Vermeij-Keers D. Oepkes J. van Roosmalen M. C. B. Gorsira 《黑龙江环境通报》1994,14(3):173-176
A fetus with multiple structural defects was seen at prenatal ultrasound examination. After termination of the pregnancy a bilateral cleft lip, alveolus, and palate; micrognathia; and webbed joints were seen. Fetal tissues showed indications of infection, intranuclear inclusion bodies, chronic stress, haemolysis, arterial wall damage, and profuse haemorrhage. Parvovirus B19 DNA was detected in fetal tissues by dot hybridization after polymerase chain reaction. The possibility of parvovirus B19 infection leading to congenital malformations is discussed. 相似文献
856.
Foci of calcification were observed at autopsy in the liver of a fetus with complete trisomy 9 on which two cordocenteses had been performed. It is suggested that liver calcifications are a possible complication of the procedure. As several other cases of calcifications in the liver and other organs of fetuses with autosomal trisomies have been described without a history of cordocentesis, further studies should be carried out to determine whether fetuses with chromosomal anomalies are more prone to thrombus formation and embolization. 相似文献
857.
J. M. Martinez A. Fortuny C. Comas B. Puerto A. Borrell M. Palacio O. Coll 《黑龙江环境通报》1994,14(8):669-672
A case of body stalk anomaly diagnosed prenatally by ultrasound during the 24th week of pregnancy in a cocaine abusing mother is presented. Accurate visualization of the fetal organs was difficult due to the severe oligohydramnios caused by premature rupture of membranes, probably related to the cocaine use. The sonographic findings were an omphalocoele, fetal attachment to the placenta, kyphoscoliosis, and absence of a floating umbilical cord. The prenatal diagnosis of the syndrome and the possible relationship with cocaine abuse are discussed. 相似文献
858.
B. N. Chodirker M.D. A. E. Chudley K. M. Macdonald C. R. Harman J. A. Evans 《黑龙江环境通报》1994,14(11):1086-1089
This study was undertaken to evaluate the relationship between maternal serum alpha-fetoprotein (MSAFP) levels and oesophageal atresia (OA). OA occurred in 16 fetuses of mothers who had an MSAFP test in the study interval. The multiple of the median (MOM) value for MSAFP averaged 1·54 ± 0·65 (range 0·5–2·9 MOM), which was significantly higher than the value seen in controls. The median MOM was 1·35. Using a cut-off of 2·5 MOM, the sensitivity of MSAFP for detecting OA was 19 per cent. Although OA should be considered in the differential diagnosis of an elevated MSAFP level, MSAFP cannot be considered an appropriate screening test for OA given the low sensitivity. 相似文献
859.
860.
Allison C. Sylvetsky Viviana Bauman Jenny E. Blau H. Martin Garraffo Peter J. Walter 《毒物与环境化学》2017,99(3):535-542
We aimed to measure concentrations of the commonly used artificial sweetener sucralose, following ingestion of doses reflecting a range of consumption and to compare concentrations in children and adults. Eleven adults consumed 355 mL water containing 0 mg (control), 68, 170, or 250 mg sucralose (equivalent to 1–4 diet sodas). A second group of adults (n = 11) consumed 355 mL Diet Rite Cola? (68 mg sucralose and 41 mg acesulfame-potassium (ace-K)) or 68 mg sucralose and 41 mg ace-K in seltzer. Beverages were provided at separate visits in randomized order, prior to an oral glucose tolerance test. Eleven children consumed 0 or 68 mg sucralose in 240 mL water, in an identical study design. Blood was collected before beverage ingestion and serially for 120 min. Sucralose doses (corrected for weight) resulted in similar plasma concentrations in children and adults. Concentrations were comparable whether sucralose was administered in water, combined with ace-K, or in diet soda. Due to their lower body weight and blood volume, children have markedly higher plasma sucralose concentrations after the consumption of a typical diet soda, emphasizing the need to determine the clinical implications of sucralose use in children. 相似文献