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71.
Molting and breeding entail major energetic costs for female crustaceans. However, females of some hermit crabs perform a
molt immediately prior to copulation (prenuptial molt). The evolutionary significance of the prenuptial molt was examined
in Pagurus hermit crabs, and two hypotheses were tested: (1) prenuptial molt might enhance the success of the present clutch by cleaning
the pleopods of females and thereby preventing eggs from being dislodged from the pleopods, and (2) prenuptial molt might
function for growth and increase future fecundity at the cost of energetic expenditure on the present brood. Although these
hypotheses are not mutually exclusive, our results rejected the former hypothesis and supported the latter hypothesis. All
four Pagurus species examined showed significant negative relationships between prenuptial molting and continuity of breeding; i.e., they
showed high molting frequency after they had a long rest period from breeding. Females of P. minutus increased their size through the prenuptial molt, and showed a decreased clutch size due to the molt. The number of dislodged
eggs increased if females molted in P. minutus. These results suggest that hermit crabs undergoing a prenuptial molt might not gain any clear immediate advantage of enhanced
survival of eggs in the present clutch, and that the prenuptial molt would mainly contribute to growth. 相似文献
72.
We studied the laxative effect of sweetening agents, hydrogenated glucose syrup (HGS) containing 88–92% maltitol, and sorbitol contained in various foods. The subjects were 89 volunteers (64 males and 25 females). Foods used in the study were tablets, bevarages, chewing gum, jelly, adzuki-bean jelly, chocolate and candies which contained one of the two sweetening agents.The doses of the sweetening agents were 0.4 g/kg for sweets in tablet form and 20 g for the other foods. Approximately 10% of the subjects exhibited diarrhea after taking tablets as a control; approximately 20% did so after taking HGS except for adzuki-bean jelly; and approximately 30% did so after taking sorbitol. There was no significant difference between HGS and the control substance. The incidence of diarrhea tended to be higher with the two sweetening agents only when contained in adzuki-bean jelly. The length of time between the ingestion of test substances and the first onset of diarrheal stool varied widely from less than one hour to 23 hours among individuals. However, adzuki-bean jelly diarrhea was induced within 5 hours in all subjects. Soft stool accounted for 60 – 90% of the macroscopic findings of diarrheal stool. Chief complaints of abdominal symptoms were gurgling, flatus and lower abdominal pain. 相似文献
73.
Daniela Bueno Sudatti Mutue Toyota Fujii Silvana Vianna Rodrigues Alexander Turra Renato Crespo Pereira 《Marine Biology》2011,158(7):1439-1446
Laurencia dendroidea shows high inter- and intrapopulation variability in the amount of the sesquiterpene elatol, caused by genetic variation
as well as environmental factors. To test the independent effect of physical and nutritional conditions, the growth and the
levels of elatol in L. dendroidea clones were evaluated under different conditions of temperature, salinity, irradiance, and culture medium in the laboratory.
Growth of L. dendroidea was clearly affected by all these factors, but elatol levels were influenced only by temperature and salinity. Better conditions
for growth did not produce a similar effect on elatol production in L. dendroidea, contradicting the carbon/nutrient balance and growth/differentiation balance models. On the contrary, severe conditions
of temperature and salinity promoted a decrease in elatol levels, as predicted by the environmental stress model. Our results
using clones indicated that abiotic factors clearly take part in fostering chemical variations observed in natural populations,
in addition to genetic factors, and can promote differential susceptibility of plant specimens to natural enemies. 相似文献
74.
This study measures productive inefficiency within the context of multi-environmental pollution (eco-efficiency) in the Chinese industrial sector. The weighted Russell directional distance model is applied to measure eco-efficiency using production technology. The objective is to clarify how external factors affect eco-efficiency. The major findings are that both foreign direct investment and investment for pollution abatement improve eco-efficiency as measured by air pollutant substances. A levy system for wastewater discharge improves eco-efficiency as measured by wastewater pollutant substances. However, an air pollutant levy does not significantly affect eco-efficiency as measured by air pollutants. 相似文献
75.
Kazuya Mimura Masayuki Endo Yoko Kawanishi Takeshi Kanagawa Kouji Nagata Keita Terui Makoto Fujii Masayuki Shiraishi Masaya Yamoto Miharu Ito Atsuo Itakura Hiroomi Okuyama Noriaki Usui the Japanese Congenital Diaphragmatic Hernia Study Group 《黑龙江环境通报》2023,43(8):993-1001
This systematic review and meta-analysis aimed to review the optimal timing of delivery at term for neonates with prenatally diagnosed congenital diaphragmatic hernia (CDH). We reviewed the literature up to December 19, 2022 using MEDLINE and the Cochrane Library databases. The inclusion criteria were original articles, comparative studies of CDH neonates delivered at an early term (37–38 weeks of gestation) and at full term (39 weeks of gestation or later), and comparative studies investigating outcomes of CDH neonates. Six studies met the inclusion criteria, including 985 neonates delivered at an early term and 629 delivered at full term. The cumulative rate of survival to discharge showed no significant difference between CDH neonates delivered at an early term (395/515; 76.7%) or at full term (345/467; 73.9%) (risk ratio [RR] 1.01; 95% confidence interval [CI], 0.89–1.16; p = 0.85). Furthermore, the number of neonates requiring oxygen therapy at discharge was not significantly different between CDH neonates delivered at an early term (32/370; 8.6%) and at full term (14/154; 9.1%) (RR, 0.99; 95% CI, 0.36–2.70; p = 0.99). Therefore, the optimal timing of delivery at term for neonates with CDH remains unclear. 相似文献
76.
77.
利用不同地方的垃圾焚烧飞灰来制备高温炉内的脱硫剂,并利用热天平来研究飞灰脱硫剂(FA-脱硫剂)的固硫性能.实验结果表明,FA-脱硫剂的孔隙分布在2000nm左右,并且比生石灰具有更好的固硫能力.添加石膏后的FA-脱硫剂,其机械强度大大提高,但孔径结构变小,脱硫率也有所下降.添加10%(质量分数)水玻璃的FA-脱硫剂的机械强度相当于生石灰,脱硫效果更明显,比没有添加水玻璃时效果更好,孔径结构基本不变.这是由于水玻璃中的钠跟二氧化硫反应生成钠硫酸盐. 相似文献
78.
Sunamura E Hoshizaki S Sakamoto H Fujii T Nishisue K Suzuki S Terayama M Ishikawa Y Tatsuki S 《Die Naturwissenschaften》2011,98(5):361-368
Some invasive ants form large networks of mutually non-aggressive nests, i.e., supercolonies. The Argentine ant Linepithema humile forms much larger supercolonies in introduced ranges than in its native range. In both cases, it has been shown that little gene flow occurs between supercolonies of this species, though the mechanism of gene flow restriction is unknown. In this species, queens do not undertake nuptial flight, and males have to travel to foreign nests and cope with workers before gaining access to alien queens. In this study, we hypothesized that male Argentine ants receive interference from workers of alien supercolonies. To test this hypothesis, we conducted behavioral and chemical experiments using ants from two supercolonies in Japan. Workers attacked males from alien supercolonies but not those from their own supercolonies. The level of aggression against alien males was similar to that against alien workers. The frequency of severe aggression against alien males increased as the number of recipient workers increased. Cuticular hydrocarbon profiles, which serve as cues for nestmate recognition, of workers and males from the same supercolony were very similar. Workers are likely to distinguish alien males from males of their own supercolony using the profiles. It is predicted that males are subject to considerable aggression from workers when they intrude into the nests of alien supercolonies. This may be a mechanism underlying the restricted gene flow between supercolonies of Argentine ants. The Argentine ant may possess a distinctive reproductive system, where workers participate in selecting mates for their queens. We argue that the aggression of workers against alien males is a novel form of reproductive interference. 相似文献
79.
Teruhiko Takahara Yukihiro Kohmatsu Atsushi Maruyama Ryohei Yamaoka 《Behavioral ecology and sociobiology》2008,63(2):235-240
When predator chemical cues are present, low activity of prey is a commonly seen defensive behavior. However, few studies
have explored the functional implications of the defensive behaviors and, thus, elucidated the possible linkages between behavioral
responses and its consequences. In this study, we experimentally investigated how behavioral responses of Hyla japonica tadpoles to predator chemical cues affect vulnerability to a dragonfly nymph Anax parthenope julius. The frequency of tadpoles attacked by dragonfly nymphs was lower with chemical cues of predator was present than without
chemical cues, and most of attacks occurred when tadpoles were mobile. When tadpoles were exposed to chemical cues, on the
other hand, their swimming speed was quicker and swimming distance was longer, respectively, and the rates of being approached
of the swimming tadpoles by dragonfly nymph was lower than those not exposed to chemical cues. We found that the tadpoles
are induced by predator chemical cues not only to generally lower activity but also to swim in bursts as additional behavior
and that the suite of their behavioral responses reduce the vulnerability against dragonfly nymph. Tadpoles can receive information
about the predation risks by chemical cues and adjust their defensive behavior accordingly. 相似文献
80.
Tomoyuki Shikata Atsushi Nukata Souta Yoshikawa Tadashi Matsubara Yasuhiro Yamasaki Yohei Shimasaki Yuji Oshima Tsuneo Honjo 《Marine Biology》2009,156(5):875-889
We investigated the effects of light quality on resting stage cell germination and vegetative cell growth of meroplanktonic
diatoms in a small port in Hakata Bay, Japan and in the laboratory. During the investigation over the year of 2006, the meroplanktonic
diatom bloom first occurred in the end of May and then repeated wane and wax until October in the small port. From late April
to middle May, light penetrating the water column was often strong and attenuations of all spectral lights were low. During
this period, Skeletonema costatum, Thalassiosira minima, and Chaetoceros sp. appeared frequently, followed by the blooms of S. costatum and Chaetoceros sp. in late May. Thereafter, S. costatum and Chaetoceros sp. bloomed in late June but not in middle June, when pigmented flagellates bloom appeared. The attenuation of short-wavelength
light such as violet and blue lights was markedly high during these diatom and flagellate blooms; all blooms disappeared within
several days. Vegetative cell strains of the three diatoms under light emitting diodes (LEDs) with six different spectra (violet,
blue, green, orange, red, and near-infrared) grew at a higher rate under short-wavelength light, violet and blue. On the other
hand, when suspensions of bottom sediments from Hakata Bay were cultured under the same LEDs and in the dark, vegetative cells
of S. costatum appeared under all LEDs except for orange and near-infrared, vegetative cells of T. minima appeared under all LEDs but not in the dark, and vegetative cells of Chaetoceros sp. appeared under violet and blue LEDs. However, vegetative cell densities of the three diatoms increased much more under
violet light than under other LEDs within a short period (6 days). Our study indicates that underwater penetration by short-wavelength
light, such as violet and blue, may be an important factor in the initiation and development of meroplanktonic diatom blooms. 相似文献