全文获取类型
收费全文 | 771篇 |
免费 | 85篇 |
国内免费 | 195篇 |
专业分类
安全科学 | 152篇 |
废物处理 | 19篇 |
环保管理 | 65篇 |
综合类 | 502篇 |
基础理论 | 138篇 |
污染及防治 | 53篇 |
评价与监测 | 34篇 |
社会与环境 | 55篇 |
灾害及防治 | 33篇 |
出版年
2024年 | 5篇 |
2023年 | 18篇 |
2022年 | 43篇 |
2021年 | 46篇 |
2020年 | 55篇 |
2019年 | 43篇 |
2018年 | 32篇 |
2017年 | 36篇 |
2016年 | 37篇 |
2015年 | 40篇 |
2014年 | 42篇 |
2013年 | 59篇 |
2012年 | 69篇 |
2011年 | 77篇 |
2010年 | 61篇 |
2009年 | 54篇 |
2008年 | 62篇 |
2007年 | 59篇 |
2006年 | 55篇 |
2005年 | 28篇 |
2004年 | 28篇 |
2003年 | 19篇 |
2002年 | 16篇 |
2001年 | 12篇 |
2000年 | 10篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1997年 | 3篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1982年 | 2篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1966年 | 1篇 |
1965年 | 2篇 |
1964年 | 2篇 |
1963年 | 1篇 |
1961年 | 1篇 |
1960年 | 1篇 |
1959年 | 1篇 |
1958年 | 2篇 |
排序方式: 共有1051条查询结果,搜索用时 754 毫秒
831.
Microgrowth patterns and the oxygen isotope composition of juvenile, shallow-marine bivalve mollusk shells of Phacosoma japonicum (Reeve) in Japan were analyzed and cross-calibrated with environmental parameters. Mark-and-recovery experiments indicate that a pair of two microgrowth lines and two microgrowth increments is produced every lunar day. This finding makes it possible to assign exact calendar dates to each portion of the shell. Average daily growth rates decrease by 61% from age two to three and 55% from age three to four. The length of the growing season and the growth rate are mainly controlled by temperature: shell growth ceases below 14.2°C (age two) and 16.8°C (age four) and is most rapid between 24.6°C and 27.2°C. Based on local temperature cycles, the growing season is longest in Seto Inland Sea, central Honshu (from May to November) and shortest at Hakodate Bay, North Japan (from June to October). The annual oxygen isotope profiles of the shells reflect the temperature cycle and the varying amounts of freshwater added to the seawater by precipitation. The most negative '18O values of -3.15 occur during the rainy season, i.e. during the monsoon and typhoon seasons. Growth rates are only slightly affected by salinity changes. Strongly reduced growth rates during the second half of the year at Seto Inland Sea and to a lesser extent at Tokyo Bay are explained by nutrient deprivation. Our study provides the basis for the use of P. japonicum in high-resolution ecological studies and environmental reconstructions. 相似文献
832.
833.
Karyotypes of the brackish-water polychaeteNeanthes japonica (Izuka) collected from five rivers in Japan from 1984 to 1988 were examined with air-drying and flame-drying methods using materials consisting of regenerating tails, clumps of spermatogonia and youngN. japonica specimens (embryos, larvae or juveniles). A diploid number of 28 was determined in well-spread metaphase chromosomes of mitotic cells. The presence of an XX-XY (male heterogametic) sex chromosome system was established for the first time in polychaetes. The Y chromosome was larger than the X chromosome. Slight differences in karyotype were found between two forms (the small- and large-egg forms), which are very similar in adult morphology but can be distinguished by reproductive and developmental characteristics. 相似文献
834.
易泽凤 《湖南环境生物职业技术学院学报》2002,8(2):143-145
在某种意义上说,人文素质比专业知识和专业技能更能反映高职院校人才培养的质量.因此,高职院校应通过加强领导、重视人文知识师资队伍的建设、推行人文课程学分制、提倡教师课后指导、开展人文素质教育活动、建立人文课程学习的评价机制等途径来加强人文素质教育. 相似文献
835.
易诚 《湖南环境生物职业技术学院学报》2007,13(4):64-66
为培养学生创新能力,结合《园艺产品贮藏加工》教学,通过改革传统的教学模式,构建理论为实践服务的实践教学主体教学体系;理论教学融入创新教育,培养学生的创新意识;实验实训,提高学生熟练的操作能力;设计综合实验、培养学生创新能力;结合科学研究、培养学生创新能力.结果表明,能较好地提高学生的综合开发及创新能力. 相似文献
836.
837.
838.
Naoko Seino Hidetaka Sasaki Junji Sato Masaru Chiba 《Atmospheric environment (Oxford, England : 1994)》2004,38(40):7073
After severe eruptions of the volcano at Miyake Island in August 2000, a large amount of volcanic gas was released into the atmosphere. To simulate flows and dispersion of sulfur dioxide (SO2) over Miyake Island, a set of numerical models was developed. The multi-nesting method was adopted to reflect a realistic meteorological field and to sufficiently resolve the flow over the island with a diameter of 8 km. The outermost model was the Regional Spectral Model (RSM) of the Japan Meteorological Agency (JMA) with a horizontal grid size of 10 km. Finer atmospheric structure was simulated with the nonhydrostatic model jointly developed by the Meteorological Research Institute and the Numerical Prediction Division of JMA (MRI/NPD-NHM) with grid intervals of 2 km, 400 m and 100 m. Realistic topography of the island was represented in the innermost model. The Lagrangian particle method was applied to the dispersion model, which is driven by the meteorological field of the 100 m grid MRI/NPD-NHM. The random walk procedure was used to represent the turbulent diffusion. The model was verified in four cases. Simulated SO2 concentrations agreed well with observed concentrations at a monitoring station including temporal variation. Under a large synoptic change, however, accurate prediction became difficult. Further numerical experiments have been done to investigate characteristics of the flow and the distribution of SO2. Steady inflows, classified according to the surface wind speed and direction, were assumed. Simulated SO2 distribution on the ground apparently depends on the surface wind. Under relatively weak inflow, there is a large diurnal change in SO2 distribution, affected by the thermally induced flow. SO2 gas is widely spread downstream in the nighttime but hardly reaches the coastal area in the daytime. On the other hand, SO2 gas steadily reached the downstream coast with little diurnal variation under the stronger inflow. Ground temperature, as well as the static stability of the inflow, also influences downstream wind, turbulent diffusivity and SO2 distribution. 相似文献
839.
Sato E Shibata K Wu YX Uezato T Kobayashi K Miura N 《Journal of environmental biology / Academy of Environmental Biology, India》2003,24(1):39-43
Skin darkened tadpoles sometimes appear spontaneously. Darkened was artificially induced in Xenopus larvae by yohimbine or chlorpromazine. These phenomena look like that are seen at pinealectomized or hypothalamus separated Xenopus larva. In this experiment, such a morphological color changed Xenopus larva is suggested by cause of inhibition of alpha2-adrenargic receptor or dopamine receptor from gastrula stages. 相似文献
840.
The acute effects of combined exposure to temperature increase and chlorination on a neritic marine copepod, Acartia omorii Bradford (collected offshore of Onjuku, Japan in 1982), were investigated in the laboratory. Continuous flow exposure and batch exposure modes were compared. Based on the results of continuous flow experiments, the 24-h median lethal concentration (24-h LC50, in mg l-1) of total residual chlorine was estimated using the multiple regression equation below, with a multiple correlation coefficient of 0.955: 24-h LC50=2.988-0.034 dT-1.611 log10
t where dT is temperature rise (°C) and t is exposure duration (min). In batch experiments, the predictive power of the multiple regression equation was reduced, probably due to variations in chlorine concentration during exposure duration. 相似文献