全文获取类型
收费全文 | 234篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 15篇 |
废物处理 | 2篇 |
环保管理 | 68篇 |
综合类 | 58篇 |
基础理论 | 46篇 |
污染及防治 | 50篇 |
评价与监测 | 5篇 |
社会与环境 | 4篇 |
灾害及防治 | 6篇 |
出版年
2023年 | 2篇 |
2021年 | 3篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2017年 | 9篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 4篇 |
2013年 | 16篇 |
2012年 | 9篇 |
2011年 | 9篇 |
2010年 | 10篇 |
2009年 | 11篇 |
2008年 | 10篇 |
2007年 | 10篇 |
2006年 | 10篇 |
2005年 | 5篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1996年 | 6篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 3篇 |
1972年 | 2篇 |
1963年 | 2篇 |
1961年 | 2篇 |
1960年 | 2篇 |
1946年 | 2篇 |
1937年 | 1篇 |
1936年 | 1篇 |
1932年 | 1篇 |
1926年 | 1篇 |
1922年 | 1篇 |
1919年 | 2篇 |
1913年 | 4篇 |
排序方式: 共有254条查询结果,搜索用时 31 毫秒
181.
Carlson PR Yarbro LA Madley K Arnold H Merello M Vanderbloemen L McRae G Durako MJ 《Environmental monitoring and assessment》2003,81(1-3):393-408
We examined the response of demographic, morphological, and chemical parameters of turtle grass (Thalassia testudinum), to much-higher-than-normal rainfall associated with an El Niño event in the winter of 1997–1998. Up to 20 inches of added rain fell between December 1997 and March 1998, triggering widespread and persistent phytoplankton blooms along the west coast of Florida. Water-column chlorophyll concentrations estimated from serial SeaWiFS imagery were much higher during the El Niño event than in the previous or following years, although the timing and magnitude of phytoplankton blooms varied among sites. Seagrass samples collected in 1997, 1998, and 1999 provided an excellent opportunity to test the responsiveness of Thalassia to decline and subsequent improvement of water quality and clarity in four estuaries. Using a scoring technique based on temporal responsiveness, spatial consistency, and statistical strength of indicators, we found that several morphological parameters (Thalassia shoot density, blade width, blade number, and shoot-specific leaf area) were responsive and consistent measures of light stress. Some morphological parameters, such as rhizome apex density, responded to declines and subsequent improvement in water clarity, but lacked the statistical discriminating power necessary to be useful indicators. However, rhizome sugar, starch, and the total carbohydrate concentrations also exhibited spatially and temporally consistent variation as well as statistical strength. Because changes in shoot density, as well as water clarity, affect rhizome carbohydrate levels, a composite metric based on Thalassia shoot density and rhizome carbohydrate levels together is probably more useful than either parameter alone as an indicator of seagrass health. 相似文献
182.
Analysis of paired-haul mid-water trawling experiments conducted in the five months November to March during the years 1985 and 1988 revealed the seasonal pattern of migration of plaice (Pleuronectes platessa L.) moving through the Dover Strait between the Southern Bight of the North Sea and the English Channel. Mid-water catches of maturing fish were highest on south-going tidesprior to peak spawning (late January), while catches of spent fish, were highest on north-going tidesafter peak spawning. Detailed analysis of the catch data provided evidence that males complete their pre-spawning migration earlier, and their post-spawning migration later, than female fish and consequently spend more time on the spawning ground. Catches of immature female fish indicated a migration south following that of the mature fish. This dummy run may be a method by which immature plaice use the presence of high densities of mature and spawning fish to learn the location of the spawning ground. The analysis also indicated that differences in catch rates between day and night are unlikely to be the result of gear avoidance by day. The results confirm that selective tidal-stream transport is a key migratory mechanism for plaice in areas of fast tidal streams on the European continental shelf. 相似文献
183.
John P. Newnham M.R.C.O.G. John V. Crues III Arnold L. Vinstein Arnold L. Medearis 《黑龙江环境通报》1984,4(6):467-471
A case of prenatal sonographic detection of a posterior mediastinal cyst in an otherwise normal fetus is presented. Following surgical excision 5 days after birth, histological examination confirmed the cyst to be gastroenteric. The differential diagnosis and clinical value of prenatal detection are discussed. 相似文献
184.
185.
This paper reports on successful prenatal diagnosis of X-linked anhidrotic ectodermal dysplasia (AED) by means of light and electron microscopy on fetal skin biopsies obtained under fetoscopy. In the present family two brothers of the proband were severely affected with the full symptomatology of AED, the pregnant female and her mother revealed minor symptoms with patches of skin lacking vellus hair. Control of lesional skin of the affected family members by electron microscopy revealed no ultrastructural abnormalities. However, all biopsies lacked skin appendages including hair follicles, sebaceous glands, and sweat glands. The lack of pilosebaceous follicles can be used as a diagnostic criterion since these structures are fully developed in normal fetuses of 20 weeks whereas the development of sweat glands does not start before week 20 to 24 of fetal life. Skin biopsies were taken from various regions of the fetus at risk via fetoscopy in week 20 and processed for light and electron microscopy. All samples revealed complete absence of all skin appendages in contrast to a total of 61 non-AED fetuses. Thus positive prenatal diagnosis of AED was made and the pregnancy was terminated. Control investigations after abortion confirmed the diagnosis. 相似文献
186.
187.
188.
189.
190.
Dr. Hans Arnold 《Die Naturwissenschaften》1913,1(36):862-865