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511.
Prenatal echographical findings of a partial sirenomelic fetus are described. An attempt was made to terminate pregnancy by administration of prostaglandin F2a, but uterine rupture occurred. The teratogenic role of vitamin A ingested by the mother in the penconceptional period is discussed.  相似文献   
512.
Work autonomy is one important component of job design theory which in recent decades has been elaborated upon by a number of researchers who have argued that it may be disaggregated into separate work method, work schedule and work criterion autonomy facets. Breaugh (1985) developed the Work Autonomy Scales as measures of each of these. This article reports the results of two studies carried out in Egypt that explored the validity of Breaugh's scales in relation to job design theory. In Study 1, in which Breaugh's scales were administered to 534 employees in two large Egyptian organizations, the Work Autonomy Scales' three‐factor structure was verified using exploratory and confirmatory factor analyses. In Study 2, using a sample of 120 managers from four organizations, the associations between the three facets of work autonomy and other variables with which they would be expected to correlate, along with their relationships with a number of outcome variables, were explored. Statistically significant correlations were observed between certain of the work autonomy scales and task interdependence, Hackman and Oldham's autonomy scale and job complexity. In terms of outcomes, work schedule autonomy was associated with job commitment, while work criterion autonomy was associated with job satisfaction. The results are discussed in the light of previous findings and some suggestions for future research are offered. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
513.
A simple and totally organic-free (green) method, viz. headspace water-based liquid-phase microextraction combined with high-performance liquid chromatography-ultraviolet detection has been successfully developed for analysis of formic acid and acetic acid in environmental water samples. A microdrop of an aqueous solution of sodium hydroxide was suspended from the tip of a microsyringe needle over the headspace of the stirred sample solution containing the analytes at pH 1.0 for a given time. The microdrop was then retracted into the microsyringe, diluted with HPLC mobile phase, and injected to HPLC. Optimum efficiency has been achieved for: 3.0 µL NaOH microdrop (0.1 mol L?1) exposed for 15 min over the headspace of an aqueous sample of 6.5 mL at 55 °C, containing 15% w/v of Na2SO4, adjusted to pH = 1.0 and stirred at 750 rpm. Under these conditions, enrichment factors of 162 and 187, limits of detection of 0.3 and 0.1 µg L?1 (S/N = 3) with dynamic linear ranges of 1–500 and 0.5–500 µg L?1 were obtained for formic acid and acetic acid, respectively. A reasonable repeatability (5.8% ≤ RSD ≤ 8.8%, n = 6) and satisfactory linearity (r2 ≥ 0.997) illustrated the performance of the method.  相似文献   
514.
This study aimed to investigate the genotoxic potential of chemicals present along the course of the river Nile using frequencies of micronuclei (MN) and nuclear lesions (NL) in erythrocytes of Nile tilapia Oreochromis niloticus niloticus and African catfish Clarias gariepinus, as biomarkers. Results showed that most of the physicochemical parameters detected and heavy metal concentrations were significantly higher in the water collected from the estuaries of the river Nile compared to other sites of the upper Nile. The frequencies of MN and NL in peripheral blood erythrocytes of Nile tilapia and African catfish were significantly higher in estuary sites in Damietta and Rosetta compared to upper sites. The lowest level of genotoxicity was observed at two sites (Aswan and Kena), considered to be less contaminated. Our results suggested that higher frequencies of MN and NL determined at Damietta and Rosetta sites may be indicative of damage produced by pollutants in these areas. The most remarkable result was that MN and NL frequencies appear to be strongly related to water quality at different sites examined, indicating that MN frequencies may serve as a reliable biomarker for testing genotoxicity in situ. The positive correlation between MN and NL induction suggested that NL may be a useful complementary assay for genotoxicity analyses when fish are used as experimental animals. It was also found that seasonal variations in MN and NL frequencies might contribute to a better understanding of genotoxic responses in the field. The use of fish as indicator organisms for monitoring the presence of genotoxic-inducing contaminants in the environment seemed justified because the effects of exposure to a “complex mixture” such as river water were obtained. Nile tilapia appears to be a more suitable bioindicator species than African catfish in studying genotoxic chemical pollution in the river Nile attributed to a higher sensitivity.  相似文献   
515.
516.
Chlorpyrifos insecticide uptake by plantain from polluted water and soil   总被引:1,自引:0,他引:1  
Chlorpyrifos is a common organophosphorus insecticide used for crop protection. Chlorpyrifos use has induced heath issues and water pollution. Such issues may be solved by phytoremediation, which is the use of plants for the cleanup of pollutants. Here, we tested Plantago major L. to clean water and soils under laboratory conditions. Results show that the concentration of chlorpyrifos residues after 5 days exposure reached 36.86 μg/g in roots and 13.93 μg/g in upper plant tissues. Gas chromatography–mass spectrometry (GC–MS) analysis of chlorpyrifos metabolites suggests the formation of 3, 5, 6-trichloro-2-pyridinol (TCP) and diethyl 3,5,6-trichloropyridin-2-yl phosphate (chlorpyrifos-oxon). Chlorpyrifos-oxon was detected in the roots and the leaves after 2 h of testing. After 24 h of testing, the degradation product chlorpyrifos-oxon increased in the roots and the leaves then decreased gradually until the end of testing. TCP levels increased gradually to 192 h then decreased until the end of testing.  相似文献   
517.
Kuwait Bay is an imperative characteristic of the State of Kuwait. It has a number of major activities existing around it, including, business, industrial and recreational ones. The phase of construction and development of projects, and their resulting pollution have led to major change in the features of the area. The purpose of this research is to serve as a managing tool for decision-making through the environmental assessment of Kuwait Bay. Due to the multiplicities and diversities of the man-made activities and the natural environmental setting of the bay, the impacts are out looked on a holistic approach rather than on a single approach. The methodology of assessment including, sampling and analysis of water and sediment, statistical analysis, as well as application of the Rapid Impact Assessment Matrix (RAIM) in order to analysis the impacts in an integrated approach. The southern areas of the bay are the main sources of pollution that distributed northward to cover the central region of the bay. Sulaibikhat Bay (South-West sector of the bay) is the most vulnerable area due to its exposure to anthropogenic activities such as reclamations, sewage inflow and other activities. The area near Shuwaikh Port is suffering due to reclamation processes. The northern and north-west sectors suffer from coastal erosion as well as from pollutants arriving via Shatt Al Arab.  相似文献   
518.
This study was conducted to understand the mechanisms governing P-sorption and desorption by calcareous soils (up to 48% CaCO 3). Batch experiments with KCl as background were carried out by adding varying amount of P up to 100 mgP.L?1. The desorption percentage (%DES) results show that little P was released from the adsorbed phase. Principal component analysis was applied to evaluate the combined influence of soil components on P sorption. The complex P sorption process can be related to specific soil components by the following equation: P? sorption=?2.20 (CaCO 3% )?0.04 (Fe? oxide)+0.04 (pHe)+11.02 (sand % )+3.35 (silt)?10.73 (clay)?1.24 (EC)?0.22 (OM)?0.81 (CEC)?1.93 (P? Olsen) (R2=0.9941, SSE=380). Sand% and clay% are the most significant variables for modelling P sorption data. The derived equation could be applied to predict P sorption in other soils that have similar compositions to those investigated herein. The degree of P saturation (DPS) threshold level for all soils was less than 3% except in the soil with the lowest iron oxide. All of the studied soils have exceeded the environmentally unacceptable P concentration except the soil with the lowest iron oxide content.  相似文献   
519.

Problem

Limited literature suggests that gasoline prices have substantial effects on reducing fatal crashes. However, the literature focuses only on fatal crashes and does not examine the effects on all traffic crashes.

Methods

Mississippi traffic crash data from April 2004–December 2008 from the Mississippi Highway Patrol and regular-grade unleaded gasoline price data from the Energy Information Administration of the U.S. Department of Energy were used to investigate the effects of gasoline prices on traffic safety by age, gender, and race.

Results

Gasoline prices have both short-term and intermediate-term effects on reducing total traffic crashes and crashes of females, whites, and blacks. The intermediate-term effects are generally stronger than the short-term effects. Gasoline prices also have short-term effects on reducing crashes of younger drivers and intermediate-term effects on older drivers and male drivers.

Impact on Industry

Higher gasoline taxes reduce traffic crashes and may result in additional societal benefits.  相似文献   
520.
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