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751.
752.
Merja Otronen 《Behavioral ecology and sociobiology》1998,42(3):185-191
The significance of male asymmetry in postcopulatory sexual selection was studied in the fly Dryomyza anilis by examining whether male asymmetry is related to fertilization success. The traits measured were wing length, tibia length
and the length of small and large claspers. The male claspers are situated at the tip of the abdomen, functional pair of claspers
consists of a large and a small clasper on the same side of the body. These claspers are used to tap the female abdomen after
sperm transfer, which has been shown to increase fertilization success for the mating male. Fertilization success was negatively
related to the fluctuating asymmetry of wing length, suggesting either female preference for more symmetrical males or a relationship
between male asymmetry and intrasexual selection which was reflected in mating performance. Fertilization success was also
related to the length of small claspers, decreasing with increasing length of the claspers. In addition, males with asymmetrical
small claspers enjoyed higher fertilization success than symmetrical ones. This study shows that fluctuating asymmetry in
wing length is an important fitness trait in postcopulatory sexual selection. Since male tapping affects sperm distribution
in the female's sperm storage organs, the higher fertilization success of males with asymmetrical small claspers could have
a functional relationship with the asymmetrical position of female sperm storage organs.
Received: 6 March 1997 / Accepted after revision: 8 November 1997 相似文献
753.
Sex-specific nest defense in house sparrows (Passer domesticus) varies with badge size of males 总被引:2,自引:0,他引:2
Heinz-Ulrich Reyer Wiltrud Fischer Pascale Steck Thomas Nabulon Philip Kessler 《Behavioral ecology and sociobiology》1998,42(2):93-99
According to indicator models of sexual selection, females can benefit from choosing males with above average epigamic traits,
but empirical evidence for such benefits is scarce. Here, we report results from an experiment with 29 pairs of house sparrows
(Passer domesticus) where the intensity of nest defense against a mounted mustelid predator was related to the size of the black throat and
breast patch (“badge”) in males. Using principal components analysis (PCA), original response variables of both sexes were
reduced to two factors: “Approach” to the predator and “Distant warning”. “Approach”, the more risky behavior, increased from
small- through medium- to large-badged males and decreased in their females. Since large-badged males have a higher certainty
of paternity (i.e. greater benefits from defense) and may be older and more experienced (i.e. incur lower costs), the most
likely explanation for male defense intensity increasing with badge size is an improving benefit/cost ratio. The resulting
optimal response of their females and evolutionarily stable participation in joint parental care is illustrated by a graphical
model. It shows that females would, indeed, benefit directly from choosing large-badged males. This, however, is no proof
of a direct evolutionary tie between badge size and paternal behavior, as assumed by indicator models of sexual selection.
It may simply represent a spurious relationship, originating from the correlation of badge size and defense with confidence
of paternity.
Received: 22 September 1997 / Accepted after revision: 3 November 1997 相似文献
754.
W. Andy Snedden Michael D. Greenfield Yikweon Jang 《Behavioral ecology and sociobiology》1998,43(1):59-66
In many rhythmically signaling species of acoustic insects and anurans, males form choruses at typical population densities.
Recent findings that females may prefer leading calls indicate that the timing of a male's signals relative to those of neighboring
choruses is an important component of mate attraction. Within a chorus, however, males cannot time their calls such that they
lead all neighbors. Hence, they are expected to show selective attention toward only a subset of the group. We used field
playback experiments to determine the incidence of and mechanism(s) responsible for selective attention in choruses of the
territorial grasshoppers Ligurotettix coquilletti and L. planum. Our data revealed significant selective attention in both species and are inconsistent with either fixed-threshold or fixed-number
mechanisms. Rather, regulation of selective attention by a sliding-threshold mechanism is supported. We discuss these results
in the context of the evolution of chorus structure.
Received: 24 September 1997 / Accepted after revision: 28 February 1998 相似文献
755.
The effect of male coloration on female mate choice in closely related Lake Victoria cichlids (Haplochromis nyererei complex) 总被引:12,自引:3,他引:9
We studied the effect of male coloration on interspecific female mate choice in two closely related species of haplochromine
cichlids from Lake Victoria. The species differ primarily in male coloration. Males of one species are red, those of the other
are blue. We recorded the behavioral responses of females to males of both species in paired male trials under white light
and under monochromatic light, under which the interspecific differences in coloration were masked. Females of both species
exhibited species-assortative mate choice when colour differences were visible, but chose non-assortatively when colour differences
were masked by light conditions. Neither male behaviour nor overall female response frequencies differed between light treatments.
That female preferences could be altered by manipulating the perceived colour pattern implies that the colour itself is used
in interspecific mate choice, rather than other characters. Hence, male coloration in haplochromine cichlids does underlie
sexual selection by direct mate choice, involving the capacity for individual assessment of potential mates by the female.
Females of both species responded more frequently to blue males under monochromatic light. Blue males were larger and displayed
more than red males. This implies a hierarchy of choice criteria. Females may use male display rates, size, or both when colour
is unavailable. Where available, colour has gained dominance over other criteria. This may explain rapid speciation by sexual
selection on male coloration, as proposed in a recent mathematical model.
Received: 11 April 1997 / Accepted after revision: 27 July 1997 相似文献
756.
Sexual selection in the zebra finch Taeniopygia guttata : condition, sex traits and immune capacity 总被引:5,自引:2,他引:3
The aim of this study was to test two hypotheses: (1) that condition-dependent secondary sexual traits reflect an individual's
immune capacity and (2) that immune capacity and secondary sexual traits covary with primary sex traits, specifically ejaculate
quality. We used the zebra finch Taeniopygia guttata as a study species, since the traits that females find attractive in males of this species, song rate and beak colour, are
well established. A paired experimental design comprising 31 pairs of brothers was used; for each pair, one male was assigned
to a control group provided with ad libitum food and no additional exercise, and the other male was assigned to an experimental
group which experienced additional exercise and a reduced rate of food intake. After 11 weeks, the experimental group differed
significantly from the control group in a range of variables, including body mass, haematocrit, granulocyte:lymphocyte (G:L)
ratio and several primary sex traits, indicating that condition in this group was reduced. Birds in the experimental group
showed a differential response to the treatment. We used the rank order in which birds could be captured by an experimenter
as an index of condition. Birds easily caught were assumed to be in poorer condition than those which were more difficult
to capture. Rank capture order was repeatable and was significantly correlated with the G:L ratio in the experimental group,
but not in the control group. In the experimental group, rank capture order was correlated significantly with both secondary
sex traits: birds in better condition had redder beaks and a higher song rate. However, beak colour and song rate did not
covary significantly, suggesting that these two traits provide different types of information. Secondary sex traits did not
covary with primary sex traits or any sperm features. Thus, there was no evidence for Trivers' sexual-competence hypothesis
or the phenotype-linked fertility hypothesis. We used four assays of immune capacity, two general (G:L ratio and spleen mass)
and two specific [antibody titres to sheep red blood cells (SRBCs) and Brucella abortus (BA)]. The G:L ratio was significantly higher in the experimental group, spleen mass (absolute and relative) did not differ
between the groups, anti-SRBC antibody titres were significantly higher in the control group (contrary to expectation), and
anti-BA antibody titres were close to being significantly lower in the experimental group. Within the experimental group,
there was no evidence that antibody titres covaried with secondary sex traits. Although we demonstrated that beak colour and
song rate were condition dependent, our experiment provided no evidence that either of these traits covaried with immune capacity
or sperm features.
Received: 9 February 1998 / Accepted after revision: 5 September 1998 相似文献
757.
We develop a reserve design strategy to maximize the probability of species persistence predicted by a stochastic, individual-based,
metapopulation model. Because the population model does not fit exact optimization procedures, our strategy involves deriving
promising solutions from theory, obtaining promising solutions from a simulation optimization heuristic, and determining the
best of the promising solutions using a multiple-comparison statistical test. We use the strategy to address a problem of
allocating limited resources to new and existing reserves. The best reserve design depends on emigration, dispersal mortality,
and probabilities of movement between reserves. When movement probabilities are symmetric, the best design is to expand a
subset of reserves to equal size to exhaust the habitat budget. When movement probabilities are not symmetric, the best design
does not expand reserves to equal size and is strongly affected by movement probabilities and emigration rates. We use commercial
simulation software to obtain our results. 相似文献
758.
759.
760.
物元分析法是处理不相容问题的一种有效方法。以竺山湾2010年7月水质监测数据为例,利用物元分析法分析太湖竺山湾水质监测点位分布情况,并将分析结果与系统聚类法的分析结果相比较,发现物元分析法的分析结果是准确、可信的。综合使用物元分析法和系统聚类法,最终确定水质监测点位可由14个优化至11个。 相似文献