全文获取类型
收费全文 | 4983篇 |
免费 | 40篇 |
国内免费 | 29篇 |
专业分类
安全科学 | 93篇 |
废物处理 | 302篇 |
环保管理 | 390篇 |
综合类 | 597篇 |
基础理论 | 1083篇 |
环境理论 | 6篇 |
污染及防治 | 1789篇 |
评价与监测 | 443篇 |
社会与环境 | 337篇 |
灾害及防治 | 12篇 |
出版年
2023年 | 54篇 |
2022年 | 147篇 |
2021年 | 187篇 |
2020年 | 78篇 |
2019年 | 80篇 |
2018年 | 220篇 |
2017年 | 208篇 |
2016年 | 290篇 |
2015年 | 144篇 |
2014年 | 284篇 |
2013年 | 425篇 |
2012年 | 323篇 |
2011年 | 370篇 |
2010年 | 256篇 |
2009年 | 197篇 |
2008年 | 297篇 |
2007年 | 312篇 |
2006年 | 233篇 |
2005年 | 186篇 |
2004年 | 153篇 |
2003年 | 108篇 |
2002年 | 104篇 |
2001年 | 68篇 |
2000年 | 47篇 |
1999年 | 37篇 |
1998年 | 17篇 |
1997年 | 14篇 |
1996年 | 15篇 |
1995年 | 21篇 |
1994年 | 14篇 |
1993年 | 15篇 |
1992年 | 9篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 8篇 |
1985年 | 7篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1967年 | 5篇 |
1966年 | 6篇 |
1965年 | 4篇 |
1964年 | 10篇 |
1962年 | 4篇 |
1961年 | 3篇 |
1960年 | 3篇 |
1959年 | 7篇 |
1958年 | 16篇 |
1957年 | 6篇 |
1955年 | 3篇 |
排序方式: 共有5052条查询结果,搜索用时 31 毫秒
981.
982.
Montaño-González Ricardo Iván Gutiérrez-Salmeán Gabriela Mojica-Villegas María Angélica Cristóbal-Luna José Melesio Briseño-Bugarín Jorge Chamorro-Cevallos Germán 《Environmental science and pollution research international》2022,29(12):17441-17455
Environmental Science and Pollution Research - Cadmium (Cd) is known for its many toxic effects on male population such as hypogonadism and fertility difficulties, which are oftenly associated with... 相似文献
983.
Hellebaut Anaïs Boisson Sylvain Mahy Grégory 《Environmental science and pollution research international》2022,29(54):81210-81221
Environmental Science and Pollution Research - It is often claimed that green walls (GW) and living wall systems (LWS) have a positive effect on urban air pollution problems if their plants... 相似文献
984.
Masting mediated by summer drought reduces acorn predation in Mediterranean oak forests 总被引:1,自引:0,他引:1
Temporally variable production of seed crops by perennial plants (masting) has been hypothesized to be a valuable mechanism in the reduction of seed predation by satiating and starving seed consumers. To achieve these benefits, coexisting species subjected to the same predator would benefit from a similar pattern of seeding fluctuation over time that could lead to a reduction in predation at the within-species level. We tested for the existence of an environmental factor enforcing synchrony in acorn production in two sympatric Mediterranean oaks (Quercus ilex and Q. humilis) and the consequences on within-species and between-species acorn predation, by monitoring 15 mixed forests (450 trees) over seven years. Acorn production in Q. ilex and Q. humilis was highly variable among years, with high population variability (CVp) values. The two species exhibited a very different pattern across years in their initial acorn crop size (sum of aborted, depredated, and sound acorns). Nevertheless, interannual differences in summer water stress modified the likelihood of abortion during acorn ripening and enforced within- and, particularly, between-species synchrony and population variability in acorn production. The increase in CVp from initial to mature acorn crop (after summer) accounted for 33% in Q. ilex, 59% in Q. humilis, and 60% in the two species together. Mean yearly acorn pre-dispersal predation by invertebrates was considerably higher in Q. humilis than in Q. ilex. Satiation and starvation of predators was recorded for the two oaks, and this effect was increased by the year-to-year variability in the size of the acorn crop of the two species combined. Moreover, at a longer time scale (over seven years), we observed a significant reduction in the mean proportion of acorns depredated for each oak and the variability in both species' acorn production combined. Therefore, our results demonstrate that similar patterns of seeding fluctuation over time in coexisting species mediated by an environmental cue (summer drought) may contribute to the reduction of the impact of seed predation at a within-species level. Future research should be aimed at addressing whether this process could be a factor assisting in the coexistence of Q. ilex and Q. humilis. 相似文献
985.
Survival rates of juvenile reptiles are critical population parameters but are difficult to obtain through mark-recapture programs because these small, secretive animals are rarely caught. This scarcity has encouraged speculation that survival rates of juveniles are very low, and we test this prediction by estimating juvenile survival rates indirectly. A simple mathematical model calculates the annual juvenile survival rate needed to maintain a stable population size, using published data on adult survival rates, reproductive output, and ages at maturity in 109 reptile populations encompassing 57 species. Counter to prediction, estimated juvenile survival rates were relatively high (on average, only about 13% less than those of conspecific adults) and highly correlated with adult survival rates. Overall, survival rates during both juvenile and adult life were higher in turtles than in snakes, and higher in snakes than in lizards. As predicted from life history theory, rates of juvenile survival were higher in species that produce large offspring, and higher in viviparous squamates than in oviparous species. Our analyses challenge the widely held belief that juvenile reptiles have low rates of annual survival and suggest instead that sampling problems and the elusive biology of juvenile reptiles have misled researchers in this respect. 相似文献
986.
Invisible floral larcenies: microbial communities degrade floral nectar of bumble bee-pollinated plants 总被引:2,自引:0,他引:2
The ecology of nectarivorous microbial communities remains virtually unknown, which precludes elucidating whether these organisms play some role in plant-pollinator mutualisms beyond minor commensalism. We simultaneously assessed microbial abundance and nectar composition at the individual nectary level in flowers of three southern Spanish bumble bee-pollinated plants (Helleborus foetidus, Aquilegia vulgaris, and Aquilegia pyrenaica cazorlensis). Yeasts were frequent and abundant in nectar of all species, and variation in yeast density was correlated with drastic changes in nectar sugar concentration and composition. Yeast communities built up in nectar from early to late floral stages, at which time all nectaries contained yeasts, often at densities between 10(4) and 10(5) cells/mm3. Total sugar concentration and percentage sucrose declined, and percentage fructose increased, with increasing density of yeast cells in nectar. Among-nectary variation in microbial density accounted for 65% (H. foetidus and A. vulgaris) and 35% (A. p. cazorlensis) of intraspecific variance in nectar sugar composition, and 60% (H. foetidus) and 38% (A. vulgaris) of variance in nectar concentration. Our results provide compelling evidence that nectar microbial communities can have detrimental effects on plants and/or pollinators via extensive nectar degradation and also call for a more careful interpretation of nectar traits in the future, if uncontrolled for yeasts. 相似文献
987.
Among pelagic fish, the Southwestern Atlantic menhaden genus Brevoortia (Clupeidae, Alosinae) constitutes an important species model to investigate the patterns of genetic differentiation. It is
abundant in the Río de la Plata estuary and in the Atlantic coastal lagoons system from Uruguay and Southern Brazil. To access
in the taxa discrimination and population structure in Brevoortia we perform a phylogeographic approach based on mitochondrial cytochrome b (cyt-b) sequences including 240 individuals from 16 collecting sites. Among the 720 bp cyt-b sequenced, 199 correspond to variables and 88 to phylogenetically informative sites. High values of haplotype diversity (h = 1.000) and nucleotide diversity (π = 0.061), as well as an average of 0.084 polymorphic segregating sites and 46 different haplotypes were found. Maximum likelihood
analysis based on the GTR + I + G model and Bayesian inference strongly support the idea that B. aurea is the only species of the genus inhabiting the Southwestern Atlantic region. Our analyses revealed a complex population
pattern characterized by the existence of long-term highly structured genetic assemblages of mixed stocks. Each monophyletic
entity included individuals from different collecting sites, different age groups and collected in different years. Our data
also suggest that the recruitment of unrelated mtDNA haplotypes carried out by individuals within schools could be occurring
in the same nursery areas revealing the existence of many different maternal lineages. A scenario where different simultaneously
and successively mixed mtDNA lineages remain historically connected through basal haplotypes among different clades could
explains more accurately the complex and ordered metapopulation dynamic found in this pelagic fish. 相似文献
988.
Gilad Heinisch Aldo Corriero Antonio Medina Francisco J. Abascal Jose-Miguel de la Serna Robert Vassallo-Agius Antonio Belmonte Ríos Antonio García Fernando de la Gándara Christian Fauvel Christopher R. Bridges Constantinos C. Mylonas Saadet F. Karakulak Isik Oray Gregorio De Metrio Hanna Rosenfeld Hillel Gordin 《Marine Biology》2008,154(4):623-630
Atlantic bluefin tuna (BFT; Thunnus thynnus) is a migrating species straddling the North Atlantic Ocean and Mediterranean Sea. It is assumed that this species is divided
into a western and an eastern stock, which spawn in the Gulf of Mexico and the Mediterranean Sea, respectively. To learn more
about the reproductive behavior of the eastern BFT stock, we tracked gonadal development in adult fish that were sampled between
April and July during three consecutive years (2003–2005). Sampling campaigns were carried out using common fishing methods
at selected locations within the Mediterranean Sea, namely Levantine Sea, Malta, and Balearic Islands. An additional sampling
point, Barbate, was situated northwest of the Straits of Gibraltar along the Atlantic coast. Morphometric parameters such
as the total body mass (M
B) and the weights of the gonads (M
G) were recorded, and the respective gonadosomatic index (GSI) values were calculated. The data collected revealed two important
trends: (1) GSI values are higher in fish caught in the eastern rather than the western locations across the Mediterranean
Sea, and (2) the GSI reaches maximum values between late May and early June in Levantine Sea (eastern Mediterranean Sea),
and only 2 and 4 weeks later in the central (Malta) and western (Balearic Islands) locations, respectively. The advanced gonadal
development in BFT correlates well with higher sea surface temperatures. Our findings also distinguish the northern Levantine
Sea BFT population (mean M
B 78.41 ± 4.13 kg), and the Barbate BFT population with the greatest M
B (all fish sampled > 100 kg). These data reflect a situation in which the eastern Mediterranean basin may function as a habitat
for young BFT, until they gain a larger M
B and are able to move to the Atlantic Ocean. However, the existence of genetically discrete BFT populations in the Mediterranean
Sea cannot be ruled out. 相似文献
989.
Pedro Daleo Tomás Luppi Agustina Mendez Casariego Mauricio Escapa Pablo Ribeiro Paola Silva Oscar Iribarne 《Marine Biology》2009,156(3):269-275
Size advantage in male–male competition over mates, combined with male preference over large females, is a common feature
that can drive to size assortative mating and, eventually, sexual selection. In crabs, appendage autotomy can affect assortative
mating and opportunity for sexual selection by affecting size advantage in mating contests. In this work, we evaluate the
effect of size and appendage autotomy in generating assortative mating in the mud crab Cyrtograpsus angulatus. Field observations of guarding pairs in two different populations show a positive correlation between carapace width of
males and females in both the populations. In one of the populations, incidence of appendage autotomy was low and the variability
in the size of reproductive males was lower than the variability in the size of randomly collected males (i.e. only larger
males were successful in getting a female), whereas there was no differences in the other population (i.e. most male sizes
were successful) where the incidence of appendage autotomy was very high, indicating that the importance of size is higher
when the incidence of autotomy is low. In this context, experiments (in both populations) show that, in contests for a female,
larger males outcompete smaller ones only when they had intact appendages. When males had missing chelipeds, winning or loosing
against smaller males was random. This may lead to a decrease in the importance of male size in populations with high incidence
of cheliped autotomy, affecting assortative mating and opportunity for selection and, thus, affecting selective pressures. 相似文献
990.
(Z)-Dodec-3-en-1-ol has been identified as the major component of the trail-following pheromone of nine species of Kalotermitidae
belonging to six different genera, suggesting that this compound represents a common signal in this family of termites. The
homogeneous nature of trail-following pheromones of Kalotermitidae well agrees with the monophyly of this family. It also
supports the postulated position of this family as a sister group of the Rhinotermitidae and Termitidae, which also secrete
C12-alcohols as trail-following pheromones. The significance of a trail pheromone in termites of the ‘one-piece’ life type,
which spend their whole life within the same piece of wood, is discussed. 相似文献