全文获取类型
收费全文 | 29866篇 |
免费 | 195篇 |
国内免费 | 158篇 |
专业分类
安全科学 | 496篇 |
废物处理 | 1612篇 |
环保管理 | 3383篇 |
综合类 | 4187篇 |
基础理论 | 8267篇 |
环境理论 | 7篇 |
污染及防治 | 6961篇 |
评价与监测 | 2410篇 |
社会与环境 | 2779篇 |
灾害及防治 | 117篇 |
出版年
2022年 | 183篇 |
2021年 | 177篇 |
2020年 | 136篇 |
2019年 | 153篇 |
2018年 | 1686篇 |
2017年 | 1633篇 |
2016年 | 1577篇 |
2015年 | 464篇 |
2014年 | 642篇 |
2013年 | 1646篇 |
2012年 | 1104篇 |
2011年 | 2154篇 |
2010年 | 1432篇 |
2009年 | 1341篇 |
2008年 | 1735篇 |
2007年 | 2129篇 |
2006年 | 818篇 |
2005年 | 750篇 |
2004年 | 756篇 |
2003年 | 763篇 |
2002年 | 756篇 |
2001年 | 851篇 |
2000年 | 638篇 |
1999年 | 333篇 |
1998年 | 233篇 |
1997年 | 266篇 |
1996年 | 253篇 |
1995年 | 303篇 |
1994年 | 288篇 |
1993年 | 223篇 |
1992年 | 243篇 |
1991年 | 225篇 |
1990年 | 263篇 |
1989年 | 231篇 |
1988年 | 183篇 |
1987年 | 193篇 |
1986年 | 189篇 |
1985年 | 192篇 |
1984年 | 200篇 |
1983年 | 178篇 |
1982年 | 169篇 |
1981年 | 151篇 |
1980年 | 151篇 |
1979年 | 163篇 |
1978年 | 124篇 |
1977年 | 137篇 |
1975年 | 114篇 |
1974年 | 113篇 |
1973年 | 122篇 |
1972年 | 115篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
J. H. A. M. Tuerlings MD A. S. P. M. Breed R. Vosters G. J. P. A. Anders 《黑龙江环境通报》1993,13(4):301-306
A 70,XXX, +18 karyotype was found by chorionic villus sampling, while the fetal fibroblast culture of the affected fetus revealed a 47,XX,+ 18 karyotype. From several possible mechanisms, we assume that a second gamete fusion occurred after the first cell division of the zygote. According to this interpretation, the mosaicism arose in very early pregnancy (at the two-cell stage). This discrepancy can therefore be explained by selection pressure, due to the differentiation processes in the embryonic tissues. 相似文献
992.
Lee P. Shulman MD Patricia L. Gordon Donald S. Emerson R. Sidney Wilroy Sherman Elias 《黑龙江环境通报》1993,13(5):403-409
We describe the prenatal diagnosis of isolated bilateral fetal microphthalmia in a woman at increased risk of having a fetus with microphthalmia. Ultrasound examinations at 161 and 19-5 weeks' gestation demonstrated bilateral fetal microphthalmia with no other associated structural defects. The patient elected to terminate her pregnancy at 19.5 weeks. Pathological evaluation of the products of conception obtained by dilation and evacuation confirmed the prenatal diagnosis of isolated bilateral fetal microphthalmia. 相似文献
993.
K.V.S. Badarinath Shailesh Kumar Kharol Anu Rani Sharma V. Ramaswamy D.G. Kaskaoutis H.D. Kambezidis 《Atmospheric environment (Oxford, England : 1994)》2009,43(24):3708-3716
Tropical cyclones are prominent weather systems characterized by high atmospheric pressure gradients and wind speeds. Intense tropical cyclones occur in India during the pre-monsoon (spring), early monsoon (early summer), or post-monsoon (fall) periods. Originating in both the Bay of Bengal (BoB) and the Arabian Sea (AS), these tropical cyclones often attain velocities of more than 100 km h?1 and are notorious for causing intense rain and storm surge as they cross the Indian coast. In this study, we examine the changes in the aerosol properties associated with an intense tropical cyclone “SIDR”, that occurred during 11–16 November 2007 over BoB. This cyclone, accompanied with very strong surface winds reaching 223 km h?1, caused extensive damage over Bangladesh. Ground-based measurements of Aerosol Optical Depth (AOD) in the neighboring urban environment of Hyderabad, India, showed significant variations due to changes in wind velocity and direction associated with the cyclone passage. The Terra-MODIS and AVHRR satellite images showed prevalence of dust particles mixed with emissions from anthropogenic sources and biomass-burning AS, while the aerosol loading over BoB was significantly lower. The positive values of Aerosol index (AI) obtained from the Ozone Monitoring Instrument (OMI) suggested the presence of an elevated aerosol layer over the West coast of India, AS and Thar Desert during and after the cyclone episode. Meteorological parameters from the MM5 mesoscale model were used to study the variations in winds associated with the cyclonic activity. Particulate matter loading over the region during the cyclone period increased by ~45% with an accompanying decrease in columnar aerosol optical depth. The variations in Angstrom parameters suggested coarse-mode particle loading due to dust aerosols as observed in satellite data. 相似文献
994.
The types of treatment most commonly used by pulp mills are biological treatments in combination with sedimentation or coagulation/flocculation as pretreatment. The main issues faced by these types of treatment are low efficiency in the removal of organic matter and the loss of aggregate value for the recovered fiber. Therefore, this study aims to evaluate the use of microfiltration (MF) combined with a membrane bioreactor (MBR) for the treatment of bleach pulp mill effluents. The results showed that the use of the MF-MBR system was an excellent alternative for the treatment of bleach pulp mill effluents with an average COD removal of 95%. The microfiltration allowed the recovery of fibers, which can be returned to the production process without losing economic value, and produced a better quality effluent for further treatment in the MBR. The MBR presented high efficiency removal of organic matter. 相似文献
995.
996.
997.
998.
The most common mutation in alpha-1-antitrypsin deficiency, conversion of a G to an A at base 9989 (PI-Z), was detected with the chemical cleavage of mismatch method, demonstrating the power of the method for prenatal diagnosis. Exon V of the gene was amplified using the polymerase chain reaction and heteroduplexes were formed to test for the presence of the mutation. The predicted C mismatch was readily detectable with hydroxylamine, and by making the probe from the chorionic villus sample it was possible to determine that the fetus was heterozygous, not homozygous, for the mutation. 相似文献
999.
1000.
Sirot V Tard A Venisseau A Brosseaud A Marchand P Le Bizec B Leblanc JC 《Chemosphere》2012,88(4):492-500
Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) bioaccumulate through the food chain and are therefore of public health concern. Exposure to these compounds was assessed in the second French Total Diet Study (TDS). Food samples (n=583) were collected to be representative of the whole diet of the population, prepared as consumed, and analyzed. Contamination data were combined with national individual food consumption data. Mean exposure (95th percentile) to PCDD/F+DL-PCBs was assessed to be 0.57 (1.29) pg TEQ(WHO-98) (kg bw)(-1) d(-1) in the adult population and 0.89 (2.02) pg TEQ(WHO-98) (kg bw)(-1) d(-1) in the child and teenager population. Less than 4% of the population exceeded the health-based guidance value for PCDD/F+DL-PCBs. Mean exposure (95th percentile) to the six indicator PCBs (PCB 28, 52, 101, 138, 153, 180) was estimated at 2.71 (7.90) ng (kg bw)(-1) d(-1) in the adult population and 3.77 (11.7) ng (kg bw)(-1) d(-1) in the child and teenager population. Only 2.6% of the adults [CI(95%): 1.9; 3.3] and 6.5% of the children and teenagers [5.2; 7.8] exceeded the health-based guidance value for total PCBs. These results show that the contamination levels in food and therefore the exposure of the general French population to PCDD/Fs and PCBs have declined (by a factor of 3.2 for PCDD/F+DL-PCBs and about three for total PCBs) since the last evaluation, which was conducted using another methodology in 2005 and 2007, and show the efficiency of the European risk management measures which came into force after these evaluations. 相似文献