全文获取类型
收费全文 | 35812篇 |
免费 | 300篇 |
国内免费 | 297篇 |
专业分类
安全科学 | 875篇 |
废物处理 | 1505篇 |
环保管理 | 4200篇 |
综合类 | 7607篇 |
基础理论 | 8953篇 |
环境理论 | 6篇 |
污染及防治 | 8761篇 |
评价与监测 | 2371篇 |
社会与环境 | 1955篇 |
灾害及防治 | 176篇 |
出版年
2022年 | 302篇 |
2021年 | 280篇 |
2019年 | 259篇 |
2018年 | 513篇 |
2017年 | 508篇 |
2016年 | 805篇 |
2015年 | 539篇 |
2014年 | 816篇 |
2013年 | 2675篇 |
2012年 | 1067篇 |
2011年 | 1318篇 |
2010年 | 1191篇 |
2009年 | 1225篇 |
2008年 | 1337篇 |
2007年 | 1452篇 |
2006年 | 1300篇 |
2005年 | 1328篇 |
2004年 | 1461篇 |
2003年 | 1332篇 |
2002年 | 1009篇 |
2001年 | 1361篇 |
2000年 | 938篇 |
1999年 | 606篇 |
1998年 | 432篇 |
1997年 | 408篇 |
1996年 | 448篇 |
1995年 | 460篇 |
1994年 | 451篇 |
1993年 | 403篇 |
1992年 | 417篇 |
1991年 | 399篇 |
1990年 | 435篇 |
1989年 | 412篇 |
1988年 | 343篇 |
1987年 | 319篇 |
1986年 | 287篇 |
1985年 | 304篇 |
1984年 | 339篇 |
1983年 | 320篇 |
1982年 | 351篇 |
1981年 | 315篇 |
1980年 | 270篇 |
1979年 | 296篇 |
1978年 | 248篇 |
1977年 | 227篇 |
1976年 | 219篇 |
1974年 | 208篇 |
1973年 | 208篇 |
1968年 | 199篇 |
1967年 | 223篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
621.
Y. Nassiri P. S. Rainbow C. Amiard-Triquet F. Rainglet B. D. Smith 《Marine Biology》2000,136(3):477-484
The talitrid amphipod crustacean Orchestia gammarellus (Pallas) was collected from metal-contaminated (Dulas Bay, Gironde) and control (Millport) sites in the UK and France. Irrespective
of site of origin, the amphipods showed the same physiological mechanism of trace-metal detoxification, involving the ventral
caeca. Copper was always present in lysosomal residual bodies in the ventral caeca. Following laboratory exposure to zinc
and cadmium, the lysosomes usually contained both copper and zinc but cadmium was not detectable. The lysosomal copper concentration
is positively correlated to that of sulphur, while the concentration of lysosomal zinc is related to that of phosphorus. Results
are interpreted in terms of the differential rates of turnover of metallothioneins chelating copper, zinc or cadmium.
Received: 9 February 1999 / Accepted: 2 December 1999 相似文献
622.
Biodiversity and Disease Risk: the Case of Lyme Disease 总被引:14,自引:0,他引:14
623.
624.
Genetic structure of fissiparous populations of Holothuria (Halodeima) atra on the Great Barrier Reef 总被引:1,自引:0,他引:1
Allozyme variation at five polymorphic loci was surveyed in a total of 311 individuals of the sea cucumber Holothuria (Halodeima) atra (Jäger, 1833) collected from two nearshore and two midshelf populations in the Great Barrier Reef in November 1996. Strong deviations in genotype frequencies from those expected under Hardy–Weinberg equilibrium, particularly a large number of heterozygote excesses, confirmed the occurrence of asexual reproduction. Females and males differed significantly in genotype frequencies as a result of differences in either the amount of fission in each sex or in the mortality of asexually produced recruits. The estimated maximum sexual input (number of sexually produced individuals: sample size = N*:Ni) to the two nearshore reefs (38 to 67%) was low relative to that to the two midshelf reefs (74 to 87%). The three ratios and G o :G e , N go :N i , N*:N i , (where G o = observed genotypic diversity, G e = expected genotypic diversity, N go = number of genotypes) considered to be indicators of the extent of asexual reproduction, showed a consistent trend in the degree of asexual reproduction similar to that derived from the number of regenerating individuals observed in the populations for which data were available. F-statistic analyses of clonal gene frequencies demonstrated that all populations received sexual recruits from the same gene pool. There was evidence of restricted sexual recruitment to the Fantome population, suggesting that asexual reproduction was dominant only in areas where sexual recruitment was limited by other factors. 相似文献
625.
For this study, field measurements of current profiles, buoy trajectories and the lag of two tidal stations were performed to explore the flow characteristics of Taichung Harbour. in order to distinguish the effects of wind drift current on circulation inside Taichung Harbour, field surveys during both summer and monsoon (winter) season were completed separately. the speed of the drift current was about 3.5% that of the, wind speed, based on the field data. the horizontal dispersion coefficients were close to Bowden's (1965) formula for the tidal current. the water temperature showed a two-layer profile, with the mixing thickness about 4 to 6 metres for the upper layer. the corresponding Richardson number was about 70. the tidal lag between the two tidal stations was 9.68 minutes. All the results agree well with the theoretical results. 相似文献
626.
Effects of specimen handling and otolith preparation on concentration of elements in fish otoliths 总被引:2,自引:0,他引:2
The use of otolith chemistry as a tool for analysing the biology of fishes assumes that the procedures used to collect and
prepare otoliths for analysis do not alter their composition. With otoliths of Nemadactylus macropterus, Hoplostethus atlanticus, and Rhombosolea tapirina, we show that this assumption is not valid for the elements that can be detected using electron-probe microanalysers (those
present at concentrations greater than ≃100 parts per million): all six elements routinely measured using these techniques
were affected by at least one post-mortem procedure tested. Measured concentrations of calcium and strontium were relatively
insensitive to most procedures tested, whereas concentrations of sodium, potassium, sulphur and chlorine were affected substantially
by many commonly used procedures. The ease with which otolith composition could be modified post-mortem suggests that apparent
geographic, habitat-specific or ontogenetic differences in otolith composition should be interpreted with extreme caution
because of easily induced artefacts and the problem of pseudo-replication associated with the ways otoliths are sampled and
prepared for analysis.
Received: 23 September 1996 / Accepted: 11 April 1998 相似文献
627.
Use of otoliths and eye lenses for measuring trace-metal incorporation in fishes: a biogeographic study 总被引:1,自引:0,他引:1
The otoliths and lenses of the temperate damselfish Parma microlepis (Günther) (Pomacentridae) showed similar differences in trace-metal profile for selected locations along the coast of New
South Wales, Australia. Otoliths and lenses displayed a differential ability to accumulate metals. Metal concentrations were
ranked differently in the two structures (e.g. Sr > Ba > Pb > Rb > Hg in otoliths, and Hg > Sr ≃ Rb > Pb > Ba in lenses),
and where similar metals were accumulated, they were accumulated at vastly different concentrations (e.g. Ba concentrations
in otoliths are a thousand-fold greater than in lenses). Analyses of the otoliths and lenses of P. microlepis from locations close to Sydney and up to 100 km from the city were able to distinguish amongst these locations with respect
to a number of metals, namely Ba, Mn and Hg. Multivariate analyses of otolith and lens data gave similar results among locations
(agreement was obtained for 11 out of 15 pair-wise comparisons), and differences were attributable to the differential ability
of the two structures to accumulate metals such as Mn and Hg. Trace-metal differences between locations were found to coincide
with the proximity of sewage (including industrial waste) and petroleum storage facilities to the different locations.
Received: 23 June 1997 / Accepted: 4 August 1997 相似文献
628.
629.
630.