全文获取类型
收费全文 | 32235篇 |
免费 | 300篇 |
国内免费 | 306篇 |
专业分类
安全科学 | 842篇 |
废物处理 | 1459篇 |
环保管理 | 3850篇 |
综合类 | 4740篇 |
基础理论 | 8656篇 |
环境理论 | 8篇 |
污染及防治 | 8565篇 |
评价与监测 | 2398篇 |
社会与环境 | 2119篇 |
灾害及防治 | 204篇 |
出版年
2022年 | 304篇 |
2021年 | 295篇 |
2020年 | 218篇 |
2019年 | 263篇 |
2018年 | 471篇 |
2017年 | 495篇 |
2016年 | 759篇 |
2015年 | 571篇 |
2014年 | 895篇 |
2013年 | 2659篇 |
2012年 | 1044篇 |
2011年 | 1389篇 |
2010年 | 1264篇 |
2009年 | 1220篇 |
2008年 | 1364篇 |
2007年 | 1503篇 |
2006年 | 1325篇 |
2005年 | 1096篇 |
2004年 | 1079篇 |
2003年 | 1046篇 |
2002年 | 1034篇 |
2001年 | 1391篇 |
2000年 | 977篇 |
1999年 | 573篇 |
1998年 | 408篇 |
1997年 | 403篇 |
1996年 | 445篇 |
1995年 | 462篇 |
1994年 | 435篇 |
1993年 | 382篇 |
1992年 | 395篇 |
1991年 | 354篇 |
1990年 | 375篇 |
1989年 | 370篇 |
1988年 | 319篇 |
1987年 | 296篇 |
1986年 | 257篇 |
1985年 | 271篇 |
1984年 | 293篇 |
1983年 | 276篇 |
1982年 | 294篇 |
1981年 | 238篇 |
1980年 | 210篇 |
1979年 | 260篇 |
1978年 | 198篇 |
1977年 | 204篇 |
1976年 | 167篇 |
1975年 | 159篇 |
1974年 | 156篇 |
1973年 | 165篇 |
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
81.
82.
Environmental factors have long been shown to influence species distributions, with range limits often resulting from environmental
stressors exceeding organism tolerances. However, these abiotic factors may differentially affect species with multiple life-history
stages. Between September 2004 and January 2006, the roles of temperature and nutrient availability in explaining the southern
distributions of two understory kelps, Pterygophora californica and Eisenia arborea (Phaeophyceae, Laminariales), were investigated along the coast of California, USA and the Baja California Peninsula, Mexico,
by limiting either: (a) tissue nitrogen uptake and storage by adult sporophytes during periods of elevated temperature, and/or
(b) production of embryonic sporophytes by microscopic gametophytes. Results suggest that while adult sporophytes of both
species are tolerant of high temperatures and low nutrients, reproduction by their microscopic stages is not. Specifically,
while E. arborea produced embryonic sporophytes at both 12 and 18°C, temperatures commonly observed throughout the southern portion of its
range, P. californica produced sporophytes at 12 but not at 18°C. As a result, it appears that the southern distribution of P. californica, which ends in northern Baja California, Mexico, may be limited by temperature acting on its microscopic stages. In contrast,
the ability of E. arborea’s microscopic and adult stages to tolerate elevated temperatures allows it to persist in the warmer southern waters of Baja
California, as well as to the north along the California coast where both species co-occur. 相似文献
83.
84.
85.
86.
87.
88.
89.
90.
Community evacuation following a chlorine release, Mississippi 总被引:1,自引:0,他引:1
On 7th September 1986, four miles north of Collins, Mississippi, a train transporting chlorine derailed. Two cars ruptured and gas escaped. As a result, 100 families were evacuated. To study the evacuation process, we conducted person-to-person interviews with sixty-two families staying in the evacuation center. Only 52.5% of the families received their first directive to evacuate directly from police or other officials. Delays in evacuating tended to be shorter when people were warned by the police and were told the reason for evacuating. Lack of personal transportation and preexisting health problems resulted in delays in evacuation. Concerns about evacuation included fear of looting, lack of a place to go, lack of transportation, difficulty in moving with children and elderly persons, and the need to take care of pets. One third of the interviewees reported feeling panic. Community evacuation procedures would be improved if: (1) officials contact all households directly; (2) the warning message addresses people's concerns; and (3) transportation is provided. 相似文献