全文获取类型
收费全文 | 37467篇 |
免费 | 379篇 |
国内免费 | 266篇 |
专业分类
安全科学 | 970篇 |
废物处理 | 1457篇 |
环保管理 | 4644篇 |
综合类 | 5880篇 |
基础理论 | 10117篇 |
环境理论 | 27篇 |
污染及防治 | 9892篇 |
评价与监测 | 2418篇 |
社会与环境 | 2488篇 |
灾害及防治 | 219篇 |
出版年
2022年 | 343篇 |
2021年 | 353篇 |
2020年 | 229篇 |
2019年 | 300篇 |
2018年 | 612篇 |
2017年 | 591篇 |
2016年 | 849篇 |
2015年 | 640篇 |
2014年 | 1023篇 |
2013年 | 2829篇 |
2012年 | 1238篇 |
2011年 | 1657篇 |
2010年 | 1335篇 |
2009年 | 1336篇 |
2008年 | 1652篇 |
2007年 | 1764篇 |
2006年 | 1529篇 |
2005年 | 1297篇 |
2004年 | 1276篇 |
2003年 | 1194篇 |
2002年 | 1147篇 |
2001年 | 1453篇 |
2000年 | 1036篇 |
1999年 | 632篇 |
1998年 | 478篇 |
1997年 | 490篇 |
1996年 | 490篇 |
1995年 | 551篇 |
1994年 | 491篇 |
1993年 | 448篇 |
1992年 | 456篇 |
1991年 | 418篇 |
1990年 | 432篇 |
1989年 | 451篇 |
1988年 | 375篇 |
1987年 | 334篇 |
1986年 | 317篇 |
1985年 | 342篇 |
1984年 | 328篇 |
1983年 | 346篇 |
1982年 | 363篇 |
1981年 | 304篇 |
1980年 | 280篇 |
1979年 | 309篇 |
1978年 | 250篇 |
1977年 | 221篇 |
1976年 | 221篇 |
1975年 | 215篇 |
1973年 | 199篇 |
1972年 | 230篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Among social insects such as ants, scouts that modulate their recruiting behaviour, following simple rules based on local information, generate collective patterns of foraging. Here we demonstrate that features of the abiotic environment, specifically the foraging substrate, may also be influential in the emergence of group-level decisions such as the choice of one foraging path. Experimental data and theoretical analyses show that the collective patterns can arise independently of behavioural changes of individual scouts and can result, through self-organising processes, from the physico-chemical properties of the environment that alter the dynamics of information transfer by chemical trails. 相似文献
43.
44.
J. Heinze H. Remmert F. L. Boschke D. Reinen L. Jaenicke 《Die Naturwissenschaften》1983,70(11):575-576
45.
Pheromones — semiochemicals used by insects for intraspecific chemical communication — can be isolated and with special analytical techniques their chemical structure elucidated. With stereoselective synthesis methods, presented by the preparation of sex attractants and aggregating pheromones of moths and beetles, respectively, a synthetic access to compounds is given which can be used for behavior manipulation of insects. Aside the importance of these compounds for investigations of the sensoric process the possibility of their application in an integrated and biological pest control is discussed. 相似文献
46.
Plasticity of honeybee castes 总被引:1,自引:0,他引:1
47.
Cynthia J. Sims MD Don T. Fujito Dennis R. Burholt Josef Dadok Harlan R. Giles D. Allan Wilkinson 《黑龙江环境通报》1993,13(6):473-480
We have investigated the ability of high-resolution proton NMR spectroscopy to provide a biochemical constituent screening of human amniotic fluid (AF). Proton NMR spectra were obtained at 300 MHz on AF from patients undergoing amniocentesis in the mid-trimester. Only AF from normal pregnancies (normal fetal karyotype, normal a-fetoprotein levels, normal birth outcome) was used in this study. The AF supernatant was lyophilized and resuspended in deuterated water containing 0.1 mm phosphate buffer and 6.02 mm disodium maleate. Identification of low molecular weight compounds was confirmed by two-dimensional NMR spectra (primarily correlated spectroscopy, or COSY) and standard addition techniques. A broad profile of compounds were ‘NMR visible’ in a single proton spectrum, including creatinine, glucose, organic acids (acetate, citrate, and lactate) and several amino acids (alanine, histidine, leucine, phenylalanine, tyrosine and valine). The proton spectrum was unaffected by prior freezing/thawing of AF samples. We were able to quantify compounds by comparison with an added concentration standard (maleate) at concentrations as low as 30 μm. Good agreement with literature values based on other analytical techniques was obtained. 相似文献
48.
49.
50.