全文获取类型
收费全文 | 2118篇 |
免费 | 75篇 |
国内免费 | 76篇 |
专业分类
安全科学 | 126篇 |
废物处理 | 4篇 |
环保管理 | 64篇 |
综合类 | 1775篇 |
基础理论 | 201篇 |
污染及防治 | 13篇 |
评价与监测 | 18篇 |
社会与环境 | 28篇 |
灾害及防治 | 40篇 |
出版年
2024年 | 1篇 |
2023年 | 12篇 |
2022年 | 20篇 |
2021年 | 34篇 |
2020年 | 24篇 |
2019年 | 17篇 |
2018年 | 12篇 |
2017年 | 12篇 |
2016年 | 21篇 |
2015年 | 25篇 |
2014年 | 26篇 |
2013年 | 36篇 |
2012年 | 44篇 |
2011年 | 108篇 |
2010年 | 91篇 |
2009年 | 78篇 |
2008年 | 88篇 |
2007年 | 114篇 |
2006年 | 132篇 |
2005年 | 113篇 |
2004年 | 119篇 |
2003年 | 104篇 |
2002年 | 118篇 |
2001年 | 92篇 |
2000年 | 36篇 |
1999年 | 13篇 |
1998年 | 9篇 |
1997年 | 11篇 |
1996年 | 6篇 |
1995年 | 90篇 |
1994年 | 80篇 |
1993年 | 73篇 |
1992年 | 62篇 |
1991年 | 59篇 |
1990年 | 55篇 |
1989年 | 63篇 |
1988年 | 47篇 |
1987年 | 50篇 |
1986年 | 30篇 |
1985年 | 42篇 |
1984年 | 44篇 |
1983年 | 21篇 |
1982年 | 21篇 |
1981年 | 16篇 |
排序方式: 共有2269条查询结果,搜索用时 15 毫秒
211.
Paolo Prontera Barbara Buldrini Vincenzo Aiello Rita Gruppioni Alessandra Bonfatti Giovanna Venti Alessandra Ferlini Alberto Sensi Elisa Calzolari Emilio Donti 《黑龙江环境通报》2006,26(6):571-576
We describe a 4-year-old female child with severe global mental retardation, myoclonic epilepsy, proximal hypotonia and dysmorphisms, whose prenatal diagnosis following amniocentesis revealed a constitutional female karyotype carrying a t(1;15)(q10;p11) familial reciprocal translocation. Post-natal high-resolution karyotype, Fluorescence in situ hybridization (FISH) screening for subtelomeric rearrangements, VNTR search for UPD15 in the blood and fibroblast, and WCP1 and 15 in the mother, failed to provide an explanation for the complex clinical phenotype of the proband. Since the pachytene configuration of the translocated chromosomes defines a high probability of 3:1 segregation, an extensive workup was undertaken to look for a possibly cryptic mosaicism. Four percent of the cells with trisomy 15 was found in the peripheral blood lymphocytes examined by classical cytogenetic technique and interphase FISH analysis. The clinical features associated with cryptic trisomy 15 mosaicism and the problems concerning prenatal diagnosis and genetic counselling for carriers of translocations at high risk of 3:1 segregation are discussed. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
212.
213.
M. Brasseur-Daudruy C. Garel V. Brossard F. Broux B. Heckettsweiler D. Eurin 《黑龙江环境通报》2006,26(13):1254-1255
We suggest the term ‘hyper-echogenic colon’ to describe a hyperechoic foetal colonic content with no other intestinal abnormality. This is a rare pattern, which to our knowledge, has never been correlated with a specific pathology. The accidental observation of a cystine kidney stone in an infant who presented with this sign during the prenatal period made it possible to diagnose this disease retrospectively in two other children. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
214.
215.
Rapid interphase analysis for prenatal diagnosis of translocation carriers using subtelomeric probes
Mark J. Pettenati Chris Von Kap-Herr Bethy Jackle Peggy Bobby Philip Mowrey Stuart Schwartz P. Nagesh Rao Jon Rosnes 《黑龙江环境通报》2002,22(3):193-197
Interphase fluorescence in situ hybridization (FISH) has become an accepted laboratory technique for the rapid and preliminary prenatal assessment of chromosome aneuploidy. The introduction of subtelomeric FISH probes now allows for the molecular–cytogenetic analysis of terminal chromosome rearrangements. In a prospective study, we examined the prenatal use of subtelomeric probes on interphase cells to rapidly detect the carrier status of a fetus when a parent carried a known reciprocal or Robertsonian chromosome translocation. Three of the cases were identified as being abnormal. All cases were confirmed by routine cytogenetic analysis. These findings clearly demonstrated the utility of this technique and these probes to rapidly and correctly identify balanced and unbalanced chromosome anomalies of a fetus that could result from parental translocations. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
216.
217.
遗传算法是近年来迅速发展起来的一种全新的随机搜索与优化算法,但由于其自身固有的缺陷,通常优化过程的收敛速度较慢,局部搜索能力不足,而且算法稳定性较差。而蚁群算法广泛应用在旅行商问题计算中,目前是较好的求解最短路由问题的算法之一。就其自身来说有很多优点,如正反馈性、鲁棒性和智能性,但是在寻优过程中容易陷入局部最佳的缺点。针对上述情况,将遗产算法与蚁群算法相结合,用于实际交通系统寻找最优路径的问题中,并定义了目标函数,以路径可靠性和路径长度为优化目标,寻找最合适的救灾路线。最后通过实际计算结果的对比验证,说明了该方法的有效性。 相似文献
218.
FRANCISCO PALOMARES JOSÉ ANTONIO GODOY JOSÉ VICENTE LÓPEZ‐BAO ALEJANDRO RODRÍGUEZ SEVERINE ROQUES MIREIA CASAS‐MARCE ELOY REVILLA MIGUEL DELIBES 《Conservation biology》2012,26(4):689-697
Abstract: Theory suggests that demographic and genetic traits deteriorate (i.e., fitness and genetic diversity decrease) when populations become small, and that such deterioration could precipitate positive feedback loops called extinction vortices. We examined whether demographic attributes and genetic traits have changed over time in one of the 2 remaining small populations of the highly endangered Iberian lynx (Lynx pardinus) in Doñana, Spain. From 1983 to 2008, we recorded nontraumatic mortality rates, litter size, offspring survival, age at territory acquisition, and sex ratio. We combined these demographic attributes with measures of inbreeding and genetic diversity at neutral loci (microsatellites) and genes subjected to selection (major histocompatibility complex). Data on demographic traits were obtained through capture and radio tracking, checking dens during breeding, track surveys, and camera trapping. For genetic analyses, we obtained blood or tissue samples from captured or necropsied individuals or from museum specimens. Over time a female‐biased sex ratio developed, age of territory acquisition decreased, mean litter size decreased, and rates of nontraumatic mortality increased, but there were no significant changes in overall mortality rates, standardized individual heterozygosity declined steadily, and allelic diversity of exon 2 of class II major histocompatibility complex DRB genes remained constant (2 allelic variants present in all individuals analyzed). Changes in sex ratio and age of territory acquisition may have resulted from demographic stochasticity, whereas changes in litter size and nontraumatic mortality may be related to observed increases in inbreeding. Concomitant deterioration of both demographic attributes and genetic traits is consistent with an extinction vortex. The co‐occurrence, with or without interaction, of demographic and genetic deterioration may explain the lack of success of conservation efforts with the Doñana population of Iberian lynx. 相似文献
219.
220.