全文获取类型
收费全文 | 21967篇 |
免费 | 175篇 |
国内免费 | 131篇 |
专业分类
安全科学 | 511篇 |
废物处理 | 882篇 |
环保管理 | 2235篇 |
综合类 | 6077篇 |
基础理论 | 4723篇 |
环境理论 | 7篇 |
污染及防治 | 5633篇 |
评价与监测 | 1251篇 |
社会与环境 | 877篇 |
灾害及防治 | 77篇 |
出版年
2022年 | 237篇 |
2021年 | 226篇 |
2019年 | 171篇 |
2018年 | 364篇 |
2017年 | 373篇 |
2016年 | 515篇 |
2015年 | 381篇 |
2014年 | 562篇 |
2013年 | 1524篇 |
2012年 | 641篇 |
2011年 | 836篇 |
2010年 | 706篇 |
2009年 | 724篇 |
2008年 | 862篇 |
2007年 | 859篇 |
2006年 | 744篇 |
2005年 | 639篇 |
2004年 | 655篇 |
2003年 | 590篇 |
2002年 | 543篇 |
2001年 | 692篇 |
2000年 | 446篇 |
1999年 | 327篇 |
1998年 | 225篇 |
1997年 | 214篇 |
1996年 | 214篇 |
1995年 | 257篇 |
1994年 | 269篇 |
1993年 | 216篇 |
1992年 | 241篇 |
1991年 | 249篇 |
1990年 | 271篇 |
1989年 | 243篇 |
1988年 | 196篇 |
1987年 | 188篇 |
1986年 | 198篇 |
1985年 | 191篇 |
1984年 | 207篇 |
1983年 | 199篇 |
1982年 | 211篇 |
1981年 | 215篇 |
1980年 | 177篇 |
1979年 | 187篇 |
1978年 | 155篇 |
1973年 | 150篇 |
1968年 | 157篇 |
1967年 | 186篇 |
1966年 | 166篇 |
1965年 | 158篇 |
1964年 | 155篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
621.
An amniocentesis was performed at 13.3 weeks' gestation for advanced maternal age. A mosaic sex chromosome pattern was found: of 50 cells examined, 34 had a 45,X karyotype. In 14 cells with a modal number of 46, a recognizable Y was substituted by a small non-fluorescent marker. C-banding identified the marker as an isodicentric in 12 cells. In two cells, the non-fluorescent marker appeared to be monocentric and looked like a non-fluorescent del (Yq), but could have been an isodicentric Y with inactivation of one of the centromeres. Two cells with a modal number of 47 showed two copies of the monocentric marker. Fluorescent in situ hybridization with an alpha satellite Y-specific centromeric probe confirmed the Y-chromosome origin of the markers and allowed for more accurate prenatal diagnostic information. 相似文献
622.
Prenatal diagnosis in a pregnancy at risk for a juvenile B1 variant of GM2-gangliosidosis was carried out. The biochemical study of the cultured amniocytes and the affected fetal brain is reported. The results obtained show that the sulphated artificial substrate can be used in the diagnosis of B1 variant, but not the neutral one. The accumulation of GM2-ganglioside in the fetal brain of the B1 juvenile form and an infantile form of GM2-gangliosidosis (0 variant) was compared. 相似文献
623.
624.
625.
626.
P. A. Hurley Mr R. H. T. Ward B. Teisner R. K. Iles M. Lucas J. G. Grudzinskas 《黑龙江环境通报》1993,13(10):903-908
Serum PAPP-A measurements taken from 254 women in the first trimester are reported. Eleven chromosomal abnormalities were detected. The mean serum PAPP-A levels in cases of Down syndrome were 0.44 MOM at 9 weeks gestation, 0.15 MOM at 10 weeks, and 0.29 MOM at 11 weeks. The PAPP-A level at 10 weeks was below those of pregnancies which aborted spontaneously. At 11 weeks, the pregnancies with Down syndrome recorded the lowest PAPP-A levels at that gestation. On this small sample, offering chorionic villus sampling to women with singleton pregnancies and a PAPP-A level below 0.3 MOM (approximately 6.5 per cent of this at-risk group) would have detected all the Down syndrome fetuses at 10 weeks and 50 per cent at 11 weeks without selecting those cases destined to abort. This suggests that serum PAPP-A should continue to be investigated as a potential first-trimester screening test for Down syndrome. 相似文献
627.
Wu Jin Wang Anpu Huang Yanchu Ma ciguang Y. Ii S. Daishim K. Furuy T. Kikuchi H. Matsushit K. Tanabe 《环境科学学报(英文版)》1990,2(1):27-39
A study has been made on elements organic constituents, TSP, SO2,NO2 of atmospheric pollutants in Beijing. 17 elements, and some PAHs, e. g. B(a)P, B(b, j, k)P, and B(g, h, i)P, in airborne particles by X-ray fluorescence spectroscopy and HPLC, GC/MS, have been determined respectively. It has been shown that the elements Pb, Zn, S and Cu were more enriched in fine particles and different valence states of sulfur at various sites. It was found that the concentrations of S6+ and S2-were more than 85% and less than 15% of the total sulfur respectively. Concentrations of major PAHs and sulfur-containing compounds increased in winter and in urban area. High values for Pb and Zn in city, Fe and Mn at industrial area and Cu, Al rural sites were obtained respectively. This implies the functions of different elemental sources of various sites. Thus, elements can be from distingushed anthropogenic and natural sources.The main contribution of SO2 was found of to have same seasonal variation as the anthropogenic el 相似文献
628.
Non-aqueous electrolyte solutions are nowadays intensively studied owing to their unique properties for their application in various electrochemical devices and procedures. Important advances have already been made in high-energy primary batteries, wet capacitors, electroplating, phase-transfer catalysis and electro-organic synthesis; advances are expected in further fields such as high-energy secondary batteries, non-emissive displays, solar cells, thin-film procedures and coating. A survey is given both for successful recent applications and expectations. 相似文献
629.
Catherine Potvin Petra Tschakert Frédéric Lebel Kate Kirby Hector Barrios Judith Bocariza Jaime Caisamo Leonel Caisamo Charianito Cansari Juan Casamá Maribel Casamá Laura Chamorra Nesar Dumasa Shira Goldenberg Villalaz Guainora Patrick Hayes Tim Moore Johana Ruíz 《Mitigation and Adaptation Strategies for Global Change》2007,12(8):1341-1362
This paper is part of a two-year study to investigate the feasibility of initiating a Clean Development Mechanism (CDM) project
in an indigenous community of Eastern Panamá, Ipetí-Emberá. We use participatory mapping and matrices as well as household
surveys to develop a land-use/land-cover baseline scenario and examine the role of local participation in assessing land-use
change. In Ipetí, land-use change has not occurred in a linear way over the last decades, and our data unveils socio-economic
factors as potential key drivers of change. The concordance that we observed between geographic information and individual
and collective perceptions of land-use change substantiates the possibility of using local knowledge in the establishment
of baseline data for CDM projects. Our calculations suggest that the total carbon (C) stocks in the Tierra Colectiva (TC) of Ipetí-Emberá in 2004 represents a 47% reduction from the estimated C stock at the onset of settlement in the early
1970’s. Results from the participatory assessments predict that, in 2024 and in absence of a CDM project, the C stocks will
decline from 301,859 t C in 2004 to 155,730 t C, which constitutes a reduction of 52%. The scenario with CDM estimates C stocks
of 305,853 t C for 2024, a value slightly superior to the 2004 value. In the TC there is ground to believe that cattle ranching
is likely to become an ever more important activity as the population is young and growing and cannot easily move elsewhere.
Forests tend to be cleared for cultivation while pastures are established on short fallows. Our baseline scenario underlines
the potential for a CDM project to make a significant difference in the future C stocks of this landscape. 相似文献
630.