全文获取类型
收费全文 | 3239篇 |
免费 | 111篇 |
国内免费 | 609篇 |
专业分类
安全科学 | 177篇 |
废物处理 | 197篇 |
环保管理 | 279篇 |
综合类 | 1287篇 |
基础理论 | 640篇 |
环境理论 | 1篇 |
污染及防治 | 932篇 |
评价与监测 | 195篇 |
社会与环境 | 182篇 |
灾害及防治 | 69篇 |
出版年
2023年 | 60篇 |
2022年 | 175篇 |
2021年 | 110篇 |
2020年 | 81篇 |
2019年 | 93篇 |
2018年 | 130篇 |
2017年 | 107篇 |
2016年 | 131篇 |
2015年 | 152篇 |
2014年 | 156篇 |
2013年 | 297篇 |
2012年 | 181篇 |
2011年 | 214篇 |
2010年 | 174篇 |
2009年 | 174篇 |
2008年 | 172篇 |
2007年 | 171篇 |
2006年 | 119篇 |
2005年 | 99篇 |
2004年 | 113篇 |
2003年 | 121篇 |
2002年 | 105篇 |
2001年 | 145篇 |
2000年 | 91篇 |
1999年 | 69篇 |
1998年 | 55篇 |
1997年 | 49篇 |
1996年 | 49篇 |
1995年 | 45篇 |
1994年 | 19篇 |
1993年 | 34篇 |
1992年 | 29篇 |
1991年 | 19篇 |
1990年 | 21篇 |
1989年 | 13篇 |
1988年 | 16篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 13篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1975年 | 8篇 |
1974年 | 10篇 |
1973年 | 7篇 |
1972年 | 12篇 |
1959年 | 5篇 |
1957年 | 5篇 |
排序方式: 共有3959条查询结果,搜索用时 828 毫秒
791.
地震台站如何做好防震减灾宣传科普工作 总被引:1,自引:0,他引:1
近年来,地震宣传科普工作越来越受到政府和地震部门的重视,作为地震监测系统的基本单位一地震台站如何在地震宣传科普工作发挥自己应有的作用,是一个很值得探讨的问题。本文根据地震台站自身特点和优势,从地震台站进行科普宣传工作的意义、内容、现状及建议等几个方面进行了一些探讨。 相似文献
792.
介绍了应用过滤 混凝气浮工艺治理特种有色纸废水的工程实例。主要污染物SS去除率达 84%~ 93 5% ;CODCr、BOD5 去除率均大于 88% ;色度得到相应削减 ,废水回用率达到 80 %。 相似文献
793.
黑岱沟露天煤矿排土场果园景观生态建设研究 总被引:2,自引:0,他引:2
本文通过对黑岱沟露天煤矿开发所形成新的人工环境条件下的气候和土壤等因子分析,应用景观生态学原理,规划建设了以观赏为主的果园观生态建设。通过对所载植果树和其它乔灌木的观测研究,筛选出了适宜于排土场生长的杏树、苹果梨、123苹果、山桃等果树品种,以及油松、旱柳、榆树、沙棘、玫瑰和先辈乔灌木品种,完成了排土场的景观生态建设工作,为矿区大面积土地复垦提供了依据。 相似文献
794.
795.
796.
文中叙述了1988 ̄1990年间,我国4个港湾-大连湾、天津港、深圳湾及珠江河段各疏浚区疏浚物中油类污染调查及分布状况。文中介绍了站位布设原则,样品采集、样品处理、分析测试方法。进行了沾污疏浚物油类出溶出实验,认为油类溶出实验是估价疏浚物油类污染的程度的重要手段。讨论了4港湾疏浚物油类污染水平。大连湾海域疏浚物石油污染明显,珠江河段,深圳湾及天津港疏浚物稍受影响,基本上是清洁的。 相似文献
797.
Genotoxicityofsubstitutednitrobenzenesandthequantitativestructure-activityrelationship¥HuangQingguo;LiuYongbin;WangLiansheng;... 相似文献
798.
The effect of intensity and quality of illumination on the photosynthesis of some tropical marine phytoplankton 总被引:2,自引:0,他引:2
Using solar energy as a source of illumination, photosynthesis in 11 species of marine plankton algae was studied as a function of light intensity. From the photosynthesis-light curve for each organism, the saturation points (I
k
) in different organisms were determined. Among the diatoms and flagellates, the highest I
k
(saturation point) values were found in Rhizosolenia styliformis and Dinophysis miles respectively. When the organisms were exposed to a portion of the visible spectrum starting from 700 m, the photosynthesis was found to be related to the radiant energy. The missing portions of the spectrum produced no significant change in the rate of photosynthesis. The photosynthetic response shown by the different organisms was strikingly similar, which signifies that, despite the qualitative dissimilarities which the organisms may possess in their pigment composition, they are capable of much chromatic adaptation. 相似文献
799.
A survey was done in 15 typical villages, 150 soil and 86 vegetable plant samples were taken in Jiaxin prefecture of the Taihu Lake region, northern Zhejian province. Results indicate that after 15-20 years land use changed from the paddy rice-wheat (or oilseed rape) double cropping system, to a continuous vegetable land has caused soil quality dramatic change. (1) Acidification: average soil pH was 5.4; about 61% of total samples were pH < 5.5. It was 0.9 units lower than 10 years ago with same upland vegetable cultivation and was 1.2 units lower than soil pH of paddy rice-wheat (or oilseed rape) rotation. (2) Fertilizer salt accumulation: the average salt content was 0.28%, among these about 36.2% of the total samples contained more than 0.3%. (3) Nitrate N and available phosphorus (P) over accumulation: on average it was 279 mg NO3-N/kg, and 45-115 mg P/kg. Nitrate N four times higher and available P 4-10 times more than it is in present paddy rice-wheat rotation soils respectively. This has caused wide concern because of possible groundwater and well drinking water pollution by leached nitrate N and the P losses to water by runoff from vegetable lands induce surface water eutrophication. 相似文献
800.
The spatial distribution of chlorophyll in three coral species carrying invertebrate symbionts was determined using spectral imaging techniques. From each pixel of the image, full fluorescence spectral data was obtained as well as comparative ratios of fluorescence. The multipixel fluorescence map and the relative-intensity fluorescence ratios demonstrated a high concentration of chlorophyll a next to the pits of Cryptochirus coralliodytes in Favites halicora. Spectral similarity maps of Goniastrea retiformis infested with Lithophaga lessepsiana and of Millepora dichotoma infested with Savignium milleporum revealed relatively higher chlorophyll concentrations in these two corals next to the symbionts. We hypothesize that the invertebrate symbionts fertilize their immediate surroundings with their excreta, enhancing algal growth. The spectral analysis system used in this study made it possible to distinguish such changes by spatial quantitation of the fluorescence emitted from small surface areas. 相似文献