全文获取类型
收费全文 | 6435篇 |
免费 | 50篇 |
国内免费 | 31篇 |
专业分类
安全科学 | 109篇 |
废物处理 | 391篇 |
环保管理 | 518篇 |
综合类 | 881篇 |
基础理论 | 1307篇 |
环境理论 | 6篇 |
污染及防治 | 2253篇 |
评价与监测 | 604篇 |
社会与环境 | 431篇 |
灾害及防治 | 16篇 |
出版年
2023年 | 66篇 |
2022年 | 184篇 |
2021年 | 180篇 |
2020年 | 76篇 |
2019年 | 90篇 |
2018年 | 201篇 |
2017年 | 178篇 |
2016年 | 299篇 |
2015年 | 186篇 |
2014年 | 332篇 |
2013年 | 565篇 |
2012年 | 397篇 |
2011年 | 441篇 |
2010年 | 301篇 |
2009年 | 263篇 |
2008年 | 374篇 |
2007年 | 373篇 |
2006年 | 326篇 |
2005年 | 243篇 |
2004年 | 210篇 |
2003年 | 173篇 |
2002年 | 183篇 |
2001年 | 125篇 |
2000年 | 77篇 |
1999年 | 55篇 |
1998年 | 33篇 |
1997年 | 27篇 |
1996年 | 22篇 |
1995年 | 48篇 |
1994年 | 40篇 |
1993年 | 19篇 |
1992年 | 22篇 |
1991年 | 16篇 |
1990年 | 15篇 |
1989年 | 14篇 |
1988年 | 10篇 |
1983年 | 10篇 |
1967年 | 8篇 |
1966年 | 14篇 |
1965年 | 18篇 |
1964年 | 31篇 |
1963年 | 12篇 |
1962年 | 18篇 |
1961年 | 13篇 |
1960年 | 10篇 |
1959年 | 26篇 |
1958年 | 30篇 |
1957年 | 19篇 |
1956年 | 14篇 |
1955年 | 19篇 |
排序方式: 共有6516条查询结果,搜索用时 968 毫秒
721.
The present study focuses on the use of solid waste generated by the steel works in Brazil for manufacturing clay-based structural products. The waste sample was characterized regarding chemical composition, X-ray diffraction, particle size, morphology, specific surface and plastic properties. The waste was added in gradual proportions to a kaolinitic clay from zero up to 3 wt.%. Ceramic bodies were formed by vacuum extrusion and fired at 950 degrees C. The physical-mechanical properties (linear shrinkage, water absorption, apparent density and flexural strength) of the resulting clay/solid waste mixtures were determined. In addition, leaching tests were performed according Brazilian Standards as well as a preliminary analysis of gases evolved during the thermal process. It was found that the solid waste is formed by irregular particles, ranging in size from 1 to 500 microm. The test results indicate that solid wastes generated by steel works can be used as filler in construction materials, thereby increasing reuse in an environmentally safe manner. 相似文献
722.
A rare complication of twin-to-twin transfusion syndrome (TTTS) is described: myocardial infarction of the recipient fetus. Myocardial infarction and hydrops are considered to be consequences of hypertension in the recipient. No other organs were affected. Pathological signs of intrauterine hypertension were estimated by the thickness of vessel walls and signs of hypertrophied myocardial cells. In the heart of the recipient fetus there was a chronic myocardial infarction near the apex cordis on the anterior wall with an aneurysm 4×5 mm in diameter. Diagnosis was based on light microscopic examination. The poor myocardial systolic function resulted in hydrops. Since the mother was administered β sympathomimetics in therapeutic doses the contribution of the drug to the myocardial infarction is uncertain, but we would like to suggest this as a possible adverse effect in TTTS. The present case is the first reported myocardial infarction in connection with the syndrome. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
723.
Tamás Marton Júlia Hajdú Csaba Papp Péter Patkós Ervin Hruby Zoltán Papp 《黑龙江环境通报》2001,21(6):452-456
The present study describes an association between adverse outcome in the twin-to-twin transfusion syndrome (TTTS) and pulmonary stenosis or reactive right ventricular hypertrophy. Six discordant monozygotic twin pregnancies with TTTS are described. Ventricular hypertrophy and atrioventricular valvular regurgitation occurred in all the recipient twins with pulmonary valvular stenosis in three cases and infundibular stenosis in one case. The recipient twin in one pair and both twins in another pregnancy died as a consequence of immaturity but the remaining twins all survived. Surgical intervention was required in one baby for valvular pulmonary stenosis. Our observations suggest that elevated blood pressure in the transfusion recipient may play an important role in pathogenesis. We hypothesise that both pulmonary stenosis and right chamber hypertrophy are secondary to hemodynamic changes. Although we have found valvular pulmonary stenosis in three recipients and infundibular stenosis in only one, this (obstruction to outflow) could be due to right chamber hypertrophy. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
724.
Agnès Guichet Stéphane Triau Catherine Lépinard Chantal Esculapavit Florence Biquard Philippe Descamps Férechté Encha-Razavi Dominique Bonneau 《黑龙江环境通报》2004,24(10):828-832
We report an interstitial deletion of chromosome 3q26-q28 in a fetus in which anophthalmia had been detected prenatally. FISH analysis, using BAC clones encompassing the SOX2 locus, showed that SOX2 gene was involved in the chromosomal breakpoint of the deletion. This case confirms that haploinsufficiency for SOX2 plays a crucial role in human eye development and emphasizes the necessity of careful chromosomal analysis, including FISH analysis of the 3q region, in case of prenatal discovery of anophthalmia. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
725.
726.
Dr Isabel Lorda-Sánchez Dan Diego-Alvarez Carmen Ayuso Marta Rodríguez de Alba Maria Jose Trujillo Carmen Ramos 《黑龙江环境通报》2005,25(10):934-938
Balanced reciprocal translocation is one of the known causes of recurrent spontaneous abortions. Cytogenetic studies of unbalanced miscarriages are difficult due to the growth failure of early loss and usually macerated abortions. We present a molecular study of an abortion in which the father carries a balanced reciprocal translocation t(2;17)(q32.1;q24.3) using QF-PCR and CGH techniques. DNA analysis showed the presence of a trisomy 2 due to a 3:1 interchange segregation. Recombinant events could also be investigated by comparing DNA samples from the family. We propose QF-PCR in addition to CGH as an efficient diagnostic method to improve our knowledge of unbalanced offspring in balanced translocation carriers. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
727.
728.
729.
Karen Hardy Stephen Buckley Matthew J. Collins Almudena Estalrrich Don Brothwell Les Copeland Antonio García-Tabernero Samuel García-Vargas Marco de la Rasilla Carles Lalueza-Fox Rosa Huguet Markus Bastir David Santamaría Marco Madella Julie Wilson ángel Fernández Cortés Antonio Rosas 《Die Naturwissenschaften》2012,99(8):617-626
Neanderthals disappeared sometime between 30,000 and 24,000?years ago. Until recently, Neanderthals were understood to have been predominantly meat-eaters; however, a growing body of evidence suggests their diet also included plants. We present the results of a study, in which sequential thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) were combined with morphological analysis of plant microfossils, to identify material entrapped in dental calculus from five Neanderthal individuals from the north Spanish site of El Sidrón. Our results provide the first molecular evidence for inhalation of wood-fire smoke and bitumen or oil shale and ingestion of a range of cooked plant foods. We also offer the first evidence for the use of medicinal plants by a Neanderthal individual. The varied use of plants that we have identified suggests that the Neanderthal occupants of El Sidrón had a sophisticated knowledge of their natural surroundings which included the ability to select and use certain plants. 相似文献
730.
Despite a rapidly improving fossil record, the reproductive biology of Mesozoic birds remains poorly known: only a handful of undisputed, isolated Cretaceous eggs (some containing embryonic remains) are known. We report here the first fossil evidence for a breeding colony of Mesozoic birds, preserved at the Late Cretaceous (Maastrichtian) Oarda de Jos (Od) site in the Sebe? area of Transylvania, Romania. A lens of calcareous mudstone with minimum dimensions of 80?cm length, 50?cm width and 20?cm depth contains thousands of tightly packed, morphologically homogenous eggshell fragments, seven near-complete eggs and neonatal and adult avialan skeletal elements. Eggshell forms 70–80?% of the matrix, and other fossils are entirely absent. The bones exhibit clear characters of the Cretaceous avialan clade Enantiornithes, and the eggshell morphology is also consistent with this identification. Both taphonomy and lithology show that the components of this lens were deposited in a single flood event, and we conclude that it represents the drowned remains of a larger enantiornithine breeding colony, swamped by rising water, washed a short distance and deposited in a shallow, low-energy pond. The same fate often befalls modern bird colonies. Such a large concentration of breeding birds suggests aquatic feeding in this species, augments our understanding of enantiornithine biology and shows that colonial nesting was not unique to crown birds. 相似文献