全文获取类型
收费全文 | 30354篇 |
免费 | 344篇 |
国内免费 | 457篇 |
专业分类
安全科学 | 951篇 |
废物处理 | 1440篇 |
环保管理 | 3676篇 |
综合类 | 5067篇 |
基础理论 | 7954篇 |
环境理论 | 18篇 |
污染及防治 | 8028篇 |
评价与监测 | 2070篇 |
社会与环境 | 1773篇 |
灾害及防治 | 178篇 |
出版年
2023年 | 140篇 |
2022年 | 322篇 |
2021年 | 316篇 |
2020年 | 240篇 |
2019年 | 284篇 |
2018年 | 480篇 |
2017年 | 477篇 |
2016年 | 743篇 |
2015年 | 568篇 |
2014年 | 885篇 |
2013年 | 2416篇 |
2012年 | 1060篇 |
2011年 | 1434篇 |
2010年 | 1169篇 |
2009年 | 1196篇 |
2008年 | 1437篇 |
2007年 | 1485篇 |
2006年 | 1263篇 |
2005年 | 1093篇 |
2004年 | 982篇 |
2003年 | 1075篇 |
2002年 | 950篇 |
2001年 | 1238篇 |
2000年 | 863篇 |
1999年 | 517篇 |
1998年 | 347篇 |
1997年 | 358篇 |
1996年 | 356篇 |
1995年 | 423篇 |
1994年 | 446篇 |
1993年 | 352篇 |
1992年 | 374篇 |
1991年 | 352篇 |
1990年 | 386篇 |
1989年 | 341篇 |
1988年 | 296篇 |
1987年 | 278篇 |
1986年 | 223篇 |
1985年 | 248篇 |
1984年 | 265篇 |
1983年 | 256篇 |
1982年 | 241篇 |
1981年 | 222篇 |
1980年 | 175篇 |
1979年 | 194篇 |
1978年 | 176篇 |
1975年 | 140篇 |
1974年 | 117篇 |
1972年 | 130篇 |
1971年 | 131篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
M. Marcelli M. Caburazzi A. Perilli V. Piermattei E. Fresi 《Chemistry and Ecology》2005,21(5):351-367
The towed undulating vehicle (TUV), named SARAGO, was used for two fine-scale surveys between the Italian and the Sardinian coasts during the Astraea 2 cruise (6-7 and 26-27 September 1995), studying the deep chlorophyll maximum distribution. SARAGO sections identify a sub-surface doming with higher chlorophyll a and primary production concentrations in the upwelling area of a cyclonic gyre region, detected by sea-surface temperature images. In the first section, the cyclone presents a double doming, in density and salinity, with shallower and concentrated patches of chlorophyll a for about 2 miles. Twenty days later, the second section shows that the gyre changes shape and extension, showing a single doming with higher primary production and chlorophyll a concentrations, distributed over a large area of about 40 nautical miles. SARAGO allows analysis of this high-variability phenomenon (cyclonic gyre) and allows concentrated patches (2 nm) to be identified, thus proving the importance of TUVs in the study of mesoscale processes. 相似文献
73.
74.
Spilt notochord syndrome is an extremely rare form of spinal dysraphism characterized by a complete cleft of the spine and a persistent communication between endoderm and ectoderm. A variant of split notochord syndrome was diagnosed in a 25-week-old fetus showing a prolapsed congenital colostomy and a spinal cystic lesion. The final diagnosis included protruding colon segment, imperforate anus with a rectourethral fistula and lipomyelomeningocele. The ultrasound features of the condition and the post-natal management are discussed. The neonate was successfully treated with a posterior sagittal anorectoplasty, while the lipomyelomeningocele was resected at a later stage. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
75.
76.
Relationships Between Developmental Stability and Fitness: Application for Conservation Biology 总被引:4,自引:0,他引:4
Geoffrey M. Clarke 《Conservation biology》1995,9(1):18-24
One of the most difficult tasks in conservation biology is identifying populations subject to stress before such stress has a detrimental impact on the population, thus allowing conservation and remedial action to be undertaken. Measuring fitness (fecundity, survival, etc.) changes directly is often difficult, expensive, or impractical. The ability of an organism to buffer its development against disturbances (developmental stability) is often considered an integral component of an individual's fitness. Data are presented from a number of studies that establish a clear relationship between developmental stability and fitness in response to both genetic and environmental stress. Consequently, I suggest that developmental stability may be used as a surrogate for more direct fitness estimation for use in conservation biology and biomonitoring programs and that is has widespread application as an early warning system for monitoring the effect of genetic and environmental stresses on natural populations. 相似文献
77.
78.
Coping with riverbank erosion hazard and displacement in bangladesh: survival strategies and adjustments 总被引:2,自引:0,他引:2
As a deltaic plain, Bangladesh annually experiences riverbank erosion hazard due to sudden and rapid channel shifting, particularly in the major floodplain areas of the country. Consequently, valuable cultivable land is lost; also village settlements, markets and towns are destroyed, displacing tens of thousands of people. This paper examines the magnitude of river channel migration and encroachment on land, and the nature of human adjustment systems in the Brahmaputra–Jamuna floodplain, by investigating aspects of the social and cultural dynamics of resettlement of the displaced people. Some policy measures are recommended to improve the ability of the people in the floodplain to cope with these hazards. 相似文献
79.
Earthquake hazard assessment after Mexico (1985) 总被引:1,自引:0,他引:1
Degg MR 《Disasters》1989,13(3):237-246
The 1985 Mexican earthquake ranks foremost amongst the major earthquake disasters of the twentieth century. One of the few positive aspects of the disaster is that it provided massive quantities of data that would otherwise have been unobtainable. Every opportunity should be taken to incorporate the findings from these data in earthquake hazard assessments. The purpose of this paper is to provide a succinct summary of some of the more important lessons from Mexico. It stems from detailed field investigations, and subsequent analyses, conducted by the author on the behalf of reinsurance companies. 相似文献
80.
In the past 20 years a variety of indices have been suggested for measuring the severity of trauma, however none of them meets the requirement of being a simple and objective instrument that can be utilized efficiently by lay persons and providers of health services without previous experience in triaging. A new system has been proposed which meets this requirement and which has been validated with 197 injured persons at the emergency ward of the Valle University Hospital in Call, Colombia. The instrument showed a high level of concordance with the conventional triaging method and classifies victims into four categories: critical with recovery unlikely, critical but recoverable, moderately serious, and ambulatory. There is discussion on the reliability of this instrument and it is recommended that it be validated with victims from larger disasters. Regardless, it has the advantage of being specific and free of the subjectivity that characterizes other indices. 相似文献