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排序方式: 共有259条查询结果,搜索用时 15 毫秒
201.
J. W. Wladimiroff MD Professor of Obstetrics & Gynaecology R. Heydanus P. A. Stewart T. E. Cohen-Overbeek Ch. Brezinka 《黑龙江环境通报》1993,13(7):545-549
Colour Doppler flow mapping of the renal arteries and subsequent pulsed Doppler measurement of impedance to flow in these vessels were attempted in 33 fetuses with postnatally confirmed renal pathology. The majority presented with unilateral or bilateral hydronephro-sis (n = 21) and bilateral renal agenesis (n = 8). Renal artery blood flow could be visualized in all, except for the eight cases of bilateral renal agenesis. Bilateral flow velocity recordings were collected in six out of 12 cases of bilateral hydronephrosis and in five out of nine cases of unilateral hydronephrosis. The pulsatility index (PI), as a measure of downstream impedance, was in the normal range in 16 out of 18 kidneys (88 per cent) in bilateral hydronephrosis and in 12 out of 14 kidneys (85 per cent) in unilateral hydronephrosis. The PI was significantly higher in severe hydronephrosis compared with mild hydronephrosis. In four cases of unilateral multicystic kidney, the PI was always higher on the affected side. Colour Doppler flow mapping and pulsed Doppler evaluation may be helpful in our understanding of renal vascularization in renal pathology and in confirming the diagnosis of renal agenesis. 相似文献
202.
Two consecutive pregnancies in a woman with initially undiagnosed type I distal arthrogryposis (DA) are reported. A prenatal diagnosis of the condition was made by ultrasound in the 17th week of gestation in one of the pregnancies, whereas in the subsequent pregnancy the disorder was excluded as early as 13 weeks' gestation. The diagnoses were verified at birth. The feasibility of prenatal diagnosis of DA type I in the second trimester is thus confirmed and its possibility in the late first trimester is suggested. 相似文献
203.
Summary. Male locust borers, Megacyllene robiniae
(Förster), responded to females only after contacting them
with their antennae, indicating that mate recognition was
mediated by a contact sex pheromone. GC-MS analyses of
whole-body extracts of males and females determined that the
profiles of compounds in the extracts were qualitatively similar,
but differed considerably in the ratios of compounds
between sexes. Biological activities of reconstructed blends
of the most abundant straight-chain (nC23, nC24, nC25, nC26),
methyl-branched (3me-C23, 3me-C25), and unsaturated
(Z9:C23, Z9:C25, Z9:C27 compounds in extracts from females
were assessed in arena bioassays, assessing four distinct steps
in the mating behavior sequence of males (orientation, arrestment,
body alignment, mounting and attempting to couple the
genitalia). Males were unresponsive to freeze-killed, solventwashed
females treated with blends of straight-chain and
methyl-branched alkanes, but responded strongly to females
treated with the blend of alkenes. Further trials determined
that the complete sequence of mating behaviors, up to and
including coupling the genitalia, was elicited by Z9:C25 alone.
Z9:C25 comprised 16.4 ± 1.3% of the total hydrocarbons in
whole-body hexane extracts of females and was co-dominant
with two other hydrocarbons that were not active. In contrast,
in solid phase microextraction (SPME) wipe samples from
several areas of the cuticle, Z9:C25 appeared as the single
dominant peak, comprising 34.6 – 37.8% of the sampled
hydrocarbons. Our data indicate that Z9:C25 is a contact sex
pheromone of M. robiniae, being the most abundant hydrocarbon
on the surface of the cuticular wax layer of females
where it is readily accessible to the antennae of males. 相似文献
204.
Roshila Moodley Neil A. Koorbanally MD. Shahidul Islam 《Journal of environmental science and health. Part. B》2013,48(12):938-944
Antioxidant activity in edible fruits is an important characteristic in the choice of fruits for human consumption, and has profound influence on nutrition and health. Two pharmacologically active triterpenoids, β-sitosterol and lupeol, and the powerful flavan-3-ol antioxidant, (+)-catechin, were isolated from the edible fruits of Harpephyllum caffrum while a mixture of cardanols, an alkyl p-coumaric acid ester, and (+)-catechin were isolated from the stem bark. This is the first report of these compounds being isolated from this plant. The antioxidant capacity of (+)-catechin was higher than the other isolated compounds as well as the known antioxidant, ascorbic acid. 相似文献
205.
Transformation of nitrogen dioxide into ozone and prediction of ozone concentrations using multiple linear regression techniques 总被引:1,自引:0,他引:1
Nurul Adyani Ghazali Nor Azam Ramli Ahmad Shukri Yahaya Noor Faizah Fitri MD Yusof Nurulilyana Sansuddin Wesam Ahmed Al Madhoun 《Environmental monitoring and assessment》2010,165(1-4):475-489
Analysis and forecasting of air quality parameters are important topics of atmospheric and environmental research today due to the health impact caused by air pollution. This study examines transformation of nitrogen dioxide (NO2) into ozone (O3) at urban environment using time series plot. Data on the concentration of environmental pollutants and meteorological variables were employed to predict the concentration of O3 in the atmosphere. Possibility of employing multiple linear regression models as a tool for prediction of O3 concentration was tested. Results indicated that the presence of NO2 and sunshine influence the concentration of O3 in Malaysia. The influence of the previous hour ozone on the next hour concentrations was also demonstrated. 相似文献
206.
Ming Su MD. Suruzzaman Yiping Zhu Jinping Lu Jianwei Yu Yu Zhang Min Yang 《环境科学学报(英文版)》2021,33(12):119-128
Odor problems in source water caused by 2-methylisoborneol (MIB) have been a common issue in China recently, posing a high risk to drinking water safety. The earthy-musty odorant MIB has an extremely low odor threshold (4–16 ng/L) and is hard to remove via conventional processes in drinking water plants (DWP), and therefore could easily provoke complaints from consumers. This compound is produced by a group of filamentous cyanobacteria, mainly belonging to Oscillatoriales. Different from the well-studied surface-blooming Microcystis, filamentous cyanobacteria have specific niche characteristics that allow them to stay at a subsurface or deep layer in the water column. The underwater bloom of these MIB producers is therefore passively determined by the underwater light availability, which is governed by the cell density of surface scum. This suggests that drinking water reservoirs with relatively low nutrient contents are not able to support surface blooms, but are a fairly good fit to the specialized ecological niche of filamentous cyanobacteria; this could explain the widespread odor problems in source water. At present, MIB is mainly treated in DWP using advanced treatment processes and/or activated carbon, but these post-treatment methods have high cost, and not able to deal with water containing high MIB concentrations. Thus, in situ control of MIB producers in source water is an effective complement and is desirable. Lowering the underwater light availability is a possible measure to control MIB producers according to their niche characteristics, which can be obtained by either changing the water level or other measures. 相似文献
207.
Ahmed T Pathak R Mustafa MD Kar R Tripathi AK Ahmed RS Banerjee BD 《Environmental monitoring and assessment》2011,179(1-4):293-299
Endosulfan, malathion, and phosphamidon are widely used pesticides. Subchronic exposure to these contaminants commonly affects the central nervous system, immune, gastrointestinal, renal, and reproductive system. There effects have been attributed to increased oxidative stress. This study was conducted to examine the role of oxidative stress in genotoxicity following pesticide exposure using peripheral blood mononuclear cells (PBMC) in vitro. Further possible attenuation of genotoxicity was studied using N-acetylcysteine (NAC) and curcumin as known modulators of oxidative stress. Cultured mononuclear cells was isolated from peripheral blood of healthy volunteers, and exposed to varying concentrations of different pesticides: endosulfan, malathion, and phosphamidon for 6, 12, and 24 h. Lipid peroxidation was assessed by cellular malondialdehyde (MDA) level and DNA damage was quantified by measuring 8-hydroxy-2'-deoxyguanosine (8-OH-dG) using ELISA. Both MDA and 8-OH-dG were significantly increased in a dose-dependent manner following treatment with these pesticides. There was a significant decrease in MDA and 8-OH-dG levels in PBMC when co-treated with NAC or/and curcumin as compared to pesticide alone. These results indicate that pesticide-induced oxidative stress is probably responsible for the DNA damage, and NAC or curcumin attenuate this effect by counteracting the oxidative stress. 相似文献
208.
Eight patients were referred for prenatal diagnosis for suspected fetal cytomegalovirus infection (CMV): six for documented first-trimester infection and two for abnormal ultrasound evaluation suggestive of fetal infection. Three methods of diagnosis were employed: (1) amniotic fluid viral cultures and CMV-specific IgM in fetal serum; (2) amniotic fluid cultures and detection by polymerase chain reaction amplification of CMV-specific DNA in chorionic villi; and (3) detection of CMV-specific DNA in villus samples only. Amniotic fluid cultures detected all cases of infection, but CMV-specific IgM was not a reliable indicator of infection in any case. DNA analysis correlated well with both culture results and clinical outcome. 相似文献
209.
210.
This study evaluates the long-term pulmonary complications of 25 children from a prospective, matched-control, pilot study evaluating short-term complications of early (11–14 weeks' gestation) versus traditional (15 weeks' gestation and later) genetic amniocentesis. Five children in the early amniocentesis group were found to have various respiratory difficulties, a morbidity rate comparable to that of paediatric patients in the general population. These data identify the need for larger, multicentre trials. 相似文献