全文获取类型
收费全文 | 1139篇 |
免费 | 18篇 |
国内免费 | 7篇 |
专业分类
安全科学 | 39篇 |
废物处理 | 47篇 |
环保管理 | 142篇 |
综合类 | 243篇 |
基础理论 | 237篇 |
环境理论 | 3篇 |
污染及防治 | 326篇 |
评价与监测 | 71篇 |
社会与环境 | 53篇 |
灾害及防治 | 3篇 |
出版年
2023年 | 11篇 |
2022年 | 14篇 |
2021年 | 24篇 |
2020年 | 16篇 |
2019年 | 15篇 |
2018年 | 39篇 |
2017年 | 40篇 |
2016年 | 44篇 |
2015年 | 37篇 |
2014年 | 43篇 |
2013年 | 63篇 |
2012年 | 50篇 |
2011年 | 79篇 |
2010年 | 62篇 |
2009年 | 62篇 |
2008年 | 72篇 |
2007年 | 72篇 |
2006年 | 39篇 |
2005年 | 56篇 |
2004年 | 30篇 |
2003年 | 38篇 |
2002年 | 35篇 |
2001年 | 20篇 |
2000年 | 15篇 |
1999年 | 10篇 |
1998年 | 16篇 |
1997年 | 5篇 |
1996年 | 11篇 |
1995年 | 20篇 |
1994年 | 12篇 |
1993年 | 8篇 |
1992年 | 12篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1980年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1974年 | 3篇 |
1963年 | 2篇 |
1961年 | 2篇 |
1959年 | 3篇 |
1958年 | 3篇 |
1957年 | 2篇 |
排序方式: 共有1164条查询结果,搜索用时 93 毫秒
531.
Fetal cardiac function is increasingly recognized as a marker of disease severity and prognosis in selected fetal conditions. Magnetic resonance imaging (MRI) has been used in experimental (animal) fetal cardiology but the lack of a noninvasive fetal electrocardiogram (ECG) to trigger image acquisition remains a major limiting factor precluding its application in humans. Fetal medicine specialists are therefore limited to ultrasound to evaluate human fetal cardiac function. In this review, we aim to provide a complete overview of the different ultrasound techniques that can be used for fetal cardiac function assessment and we discuss their (theoretical) strengths and shortcomings. Conventional methods include M-mode assessment of ventricular contractility and Doppler assessment of the precordial veins and cardiac output (CO). More recent techniques such as the measurement of the myocardial performance index (MPI), myocardial motion analysis with tissue Doppler, speckle tracking and three-dimensional (3D) ultrasound techniques are also discussed. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
532.
533.
Jan J. de Vlieger 《The Environmentalist》2008,28(1):45-48
In the FAIR project “Pheromaize”, CT96-1302, the main objective is to provide European growers with a reliable, cost effective
and environmentally friendly technology based on pest mating disruption. The project is mainly focused on Mediterranean Corn
Borer (MCB), Sesamia nonagroides, the key pest of maize grown under Mediterranean conditions. TNO has developed a sprayable formulation consisting of a biodegradable
matrix in which␣the pheromone is dissolved, together with a UV––stabilizer, an antioxidant, a surfactant and a sticker material.
During outdoor exposure experiments release of pheromone was found to be high enough for more than 30 days. This formulation
has been tested in large scale field experiments by helicopter spraying on 5 ha maize by field partners in Spain, Greece and
France. 相似文献
534.
The purpose of this study was to improve risk management and to investigate build-up of the costs of fire in waste-fuel stores,
to make the authorities and the population in general aware of the substantial monetary and non-material benefits connected
with preventive measures being taken. To summarize, the results from the case studies show that the fires occurred by self-ignition
of organic materials, the storage facilities were badly and/or not properly designed, and the waste fuels were not handled
properly. On the basis of two case studies the main finding was that there must be one person only in charge during the fire
to lead the action, and the fire brigade must not leave the area too early. Nowadays, the real cost for the fire is not calculated
properly, or at all, by the waste-management company. It is concluded that waste-management companies, society, and insurance
companies could save money by implementation of precautionary measures. Such relevant measures are reviewed. It is recommended:
not to store waste fuels too high, in volumes which are too large or too close to town districts; to promote better cooperation
between waste companies and the fire brigades and the local EPA; and to make insurance companies demand implementation of
more security measures before signing the insurance contracts. 相似文献
535.
536.
537.
Jan A. Deprest Alan W. Flake Eduard Gratacos Yves Ville Kurt Hecher Kypros Nicolaides Mark P. Johnson François I. Luks N. Scott Adzick Michael R. Harrison 《黑龙江环境通报》2010,30(7):653-667
Fetal diagnosis prompts the question for fetal therapy in highly selected cases. Some conditions are suitable for in utero surgical intervention. This paper reviews historically important steps in the development of fetal surgery. The first invasive fetal intervention in 1963 was an intra-uterine blood transfusion. It took another 20 years to understand the pathophysiology of other candidate fetal conditions and to develop safe anaesthetic and surgical techniques before the team at the University of California at San Francisco performed its first urinary diversion through hysterotomy. This procedure would be abandoned as renal and pulmonary function could be just as effectively salvaged by ultrasound-guided insertion of a bladder shunt. Fetoscopy is another method for direct access to the feto-placental unit. It was historically used for fetal visualisation to guide biopsies or for vascular access but was also abandoned following the introduction of high-resolution ultrasound. Miniaturisation revived fetoscopy in the 1990s, since when it has been successfully used to operate on the placenta and umbilical cord. Today, it is also used in fetuses with congenital diaphragmatic hernia (CDH), in whom lung growth is triggered by percutaneous tracheal occlusion. It can also be used to diagnose and treat urinary obstruction. Many fetal interventions remain investigational but for a number of conditions randomised trials have established the role of in utero surgery, making fetal surgery a clinical reality in a number of fetal therapy programmes. The safety of fetal surgery is such that even non-lethal conditions, such as myelomeningocoele repair, are at this moment considered a potential indication. This, as well as fetal intervention for CDH, is currently being investigated in randomised trials. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
538.
Spontaneous vegetation succession at different central European mining sites: a comparison across seres 总被引:2,自引:0,他引:2
Karel Prach Kamila Lencová Klára Řehounková Helena Dvořáková Alena Jírová Petra Konvalinková Ondřej Mudrák Jan Novák Romana Trnková 《Environmental science and pollution research international》2013,20(11):7680-7685
We performed detrended correspondence analysis (DCA) ordination to compare seven successional seres running in stone quarries, coal mining spoil heaps, sand and gravel pits, and extracted peatlands in the Czech Republic in central Europe. In total, we obtained 1,187 vegetation samples containing 705 species. These represent various successional stages aged from 1 to 100 years. The successional seres studied were more similar in their species composition in the initial stages, in which synathropic species prevailed, than in later successional stages. This vegetation differentiation was determined especially by local moisture conditions. In most cases, succession led to a woodland, which usually established after approximately 20 years. In very dry or wet places, by contrast, where woody species were limited, often highly valuable, open vegetation developed. Except in the peatlands, the total number of species and the number of target species increased during succession. Participation of invasive aliens was mostly unimportant. Spontaneous vegetation succession generally appears to be an ecologically suitable and cheap way of ecosystem restoration of heavily disturbed sites. It should, therefore, be preferred over technical reclamation. 相似文献
539.
Slavka Flesarova Norbert Lukac Jan Danko Peter Massanyi 《Journal of environmental science and health. Part. B》2013,48(3):329-334
In this study histological structure of rabbit thymus after bendiocarbamate (2,3–isopropyledene–dioxyphenyl methylcarbamate) administration was studied. Bendiocarbamate was perorally administered for 90 days. At Day 3, 10, 20, 30, 60, 90 morphometric analysis was realized. Quantitative evaluation showed that in the control group thymus cortex forms 57.94 ± 7.10% and medulla 35.94± 7.38%. In almost all experimental groups significantly higher relative volume of cortex and lower relative volume of medulla was detected. Detail morphometric analysis found that the number of thymocytes per constant area and the diameter of tymocytes was decresed after bendiocarbamate administration. The number and diameter of reticular cells was not affected. Results of this study suggest negative effect of bendiocarbamate on the formation of thymus structures. 相似文献
540.
De Wit Helene A. Mulder Jan Nygaard Per H. Aamlid Dan Huse Magne Kortnes Egil Wollebæk Gro Brean Roald 《Water, Air, & Soil Pollution: Focus》2001,1(1-2):103-118
Aluminium (Al) is a key element in critical loadcalculations for forest. Here, we argue for re-evaluating theimportance of Al. Effects of two levels of enhanced Alconcentrations and lowered Ca:Al ratios in the soil solutionin a field manipulation experiment in a mature spruce stand(1996–1999) on tree vitality parameters were tested. Inaddition, Al solubility controls were tested. Various loads ofAl were added to forest plots by means of an irrigationsystem. Potentially toxic Al concentrations and criticalratios of Ca to inorganic Al were established. The ratio of Cato total Al was not a suitable indicator for unfavourableconditions for plant growth. No significant effects on crowncondition, tree growth and fine root production were observedafter three years of treatment. In 1999, foliar Mg content inthe highest Al addition treatment had declined significantly.This agreed with the known response to Al stress of seedlingsin nutrient solution experiments. No support was found forusing the chemical criterion Ca:Al ratio in soil solution,foliar and root tissue as an indicator for forest damage dueto acidification. Al solubility was considerably lower thanimplied by the assumption of equilibrium with gibbsite,particularly in the root zone. The gibbsite equilibrium iscommonly used in critical load models. Substitution of thegibbsite equilibrium with an Al-organic matter complexationmodel to describe Al solubility in soil water may have largeconsequences for calculation of critical loads. The resultsindicate that critical load maps for forests should bereconsidered. 相似文献