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91.
92.
Endeis laevis (Grube) is the more littoral of the two British members of the Endeidae (Pycnogonida). The process of vitellogenesis is examined. It closely resembles that of annelids and Limulus polyphemus, in which the majority of the yolk is synthesised within the oocyte with only a small contribution from outside the oocyte. This contrasts with the method in insects in which most of the yolk comes from outside the oocyte. The vitellogenic process is slow, the eggs accumulating yolk over the winter. Although E. laevis has two reproductive cycles each year, only one brood is produced, juveniles occurring over a restricted period (July and early August).  相似文献   
93.
Summary. During peak calling activity by male oil palm bunch moths, Tirathaba mundella Walker (Lepidoptera: Pyralidae), their hairpencils, wings or entire body were extracted in hexane. Gas chromatographic-electroantennographic detection (GC-EAD) analyses of hair pencil extracts revealed four compounds that consistently elicited responses from female antennae. The NMR spectrum of isolated compound 1, and mass spectra and retention indices of compounds 1–4 suggested that they were (3S,6S)-2,2,6-trimethyl-6-vinyl-tetrahydro-pyran-3-ol (1), 4-hydroxy-3-methoxy-benzaldehyde (2, vanillin), 6,10,14-trimethyl-2-pentadecanone (3), and 6,10,14-trimethyl-2-pentadecanol (4). Comparative GC and GC-MS analyses of hair pencils extract and synthetic standards confirmed these structural assignments. Moreover, comparative chromatography of synthetic and hairpencil-isolated 1 on a Cyclodex-B column (which separated the four stereoisomers with baseline resolution) revealed that male T. mundella produce the SS-stereoisomer (SS-1). In field cage bioassay experiments in Palembang, Indonesia, synthetic SS-1 and vanillin in combination, but not singly, attracted female T. mundella. SS-1 plus vanillin were as effective as male T. mundella in attracting females. Compounds 3 and 4 did not enhance the blend's attractiveness. Received October 11 2002; accepted March 14, 2003. R1D=" Correspondence to: Gerhard Gries, email: gries@sfu.ca  相似文献   
94.
Observations from a one-person submersible (Wasp) in fall, 1982, revealed a persistent aggregation of non-migrating, Stage V copepodites of Calanus pacificus californicus Brodsky in a band 20±3 m thick at a depth of 450 m, about 100 m above the bottom of the Santa Barbara Basin, California. Copepod abundances, calculated from nearest-neighbor distances measured directly from the submersible, yielded maximum densities of 26×106 copepodites m-3. Quiescent behavior, low laminarinase activity, low protein content, high lipid content and evidence of low excretion rate all suggest that these copepodites were in a state of diapause. Diapausing C. pacificus californicus at other locations along the eastern Pacific coast were also captured in discrete depth plankton tows. Both the submersible observations and the net collections suggest that the dense aggregation of diapausing copepods we observed in the Santa Barbara Basin was a phenomenon associated with seasonal upwelling cycles, and that such aggregations occur during non-upwelling periods when food is scarce in surface waters. Numerous predators, especially the deep sea smelt Leuroglossus stilbius, were observed feeding upon the aggregated copepods; thus, in contrast to the conventional picture of surface-dominated food distribution, deep-water aggregations of C. pacificus californicus may support the mesopelagic community during periods of low food availability in surface waters.  相似文献   
95.
海洋微藻活体及乙醇固定状态下基因组DNA的微量提取方法   总被引:1,自引:0,他引:1  
探讨了海洋微藻活体及固定状态下基因组DNA的提取方法,即作者改进的CTAB法.结果表明,CTAB改进法提取的基因组DNA蛋白质、酚、盐和小分子的污染较少,多糖成份也得到了有效去除.用5%乙醇固定样本提取DNA的效果最好,对原生动物抑制效果也较明显;10%以上的乙醇可杀死原生动物,但对DNA的降解率较大;30%以上的乙醇对细菌抑制较明显,但DNA都有较大程度的降解.本法提取的DNA可用于正常的酶切和PCR.用甲醛、甲醇/冰醋酸等其它固定液固定样品,DNA的得率低或者质量和纯度低.图7表1参27  相似文献   
96.
本文对1996-2000年全区城市环境综合整治定量考核工作进行了全面的分析,介绍了目前“城考”工作的状况,总结了经验,对今后的“城考”工作提出了建议。  相似文献   
97.
植树造林已普遍作为减缓全球变暖的主要对策之一,其主导思想是利用森林的光合作用吸收大气中的CO_2。目前很少人注意到缓解全球变暖的另一种途径,即从森林生物量中获取替代矿物燃料的生物能源。  相似文献   
98.
Background: Road traffic injuries (RTIs) are a serious epidemic that claims more than a million lives across the globe each year. The burden of RTIs is particularly pronounced in Africa and other low- and middle-income countries. The unfavorable disparity of the burden of road trauma in the world is largely attributable to unsafe vehicles, lack of appropriate road infrastructure, and the predominance of vulnerable road users (VRUs) in developing countries. However, little research exists in northern Ghana to highlight the scale and risk of death among road users.

Objective: The objective of this research was to establish the relative risk of death among road users in northern Ghana.

Methods: Crash data from police reports between 2007 and 2011 were analyzed for the Upper Regions of Ghana. Conditional probabilities and multivariable logistic regression techniques were used to report proportions and adjusted odds ratios (AORs), respectively.

Results: Generally, crashes in northern Ghana were extremely severe; that is, 35% of all injury related collisions were fatal. The proportion of fatal casualties ranged between 21% among victims of sideswipe collisions and 41% among pedestrians and victims of rear-end collisions. Though males were 6 times more likely to die than females overall, females were more likely to die as pedestrians (90% of all female casualty deaths) and males were more likely to die as riders/drivers (78% of all male casualty deaths). Pedestrians were 3 times more likely to die (odds ratio [OR] = 3.1; 95% confidence interval [CI], 2.4 to 4.1) compared with drivers/riders. Compared with drivers, the odds of death among cyclists was about 4 times higher (AOR = 3.6; 95% CI, 2.3 to 5.6) and about 2 times higher among motorcyclists (AOR = 1.6; 95% CI, 1.2 to 2.2). Compared with casualties aged between 30 and 59 years, children under 10 years and those aged 60 years and above were independently 2 times more likely to die in traffic collisions.

Conclusion: Provision of requisite road infrastructure is vital for the safety of VRUs in northern Ghana. Cycle paths and lanes (for cyclists) as well as sidewalks (for pedestrians) in particular will separate VRUs from motorists and improve their safety. Enforcement of traffic laws particularly regarding helmet use, speeding, and alcohol use will be beneficial. Introduction of the demerit points system in the enforcement of traffic regulations may have significant deterrent effects on road users who have the penchant for violating traffic regulations. Road safety education is also required to create responsible road users.  相似文献   

99.
以亚氨基二琥珀酸(ISA)为洗脱剂,考察ISA投加量、洗脱液pH值、反应时间和土液比对Cd、Pb和Zn去除率影响,通过Box-Behnken多因素设计法优化最佳洗脱条件,并采用涵盖土壤重金属残留量、浸出浓度和毒性的综合环境风险法评估修复效果.结果表明,ISA对Cd、Pb和Zn去除率随其浓度增加而增加;ISA浓度为50mmol/L时,对矿山污染土壤中Cd、Pb和Zn去除率达到11.83%、34.26%和20.96%;对污染农田土壤中Cd、Pb和Zn去除率达到48.89%、57.08%和81.80%.增加反应时间和洗脱液酸性有助于提高ISA对Cd、Pb和Zn去除率.随土液比减低,Cd、Pb和Zn去除率呈上升趋势.ISA去除Cd、Pb和Zn最佳条件为:ISA浓度70mmol/L、洗脱液pH4.0和反应时间120min,预测矿山土壤和污染农田土壤中Cd、Pb和Zn总去除率最大分别为32.58%和93.16%.ISA大幅度降低水溶态、可交换态和碳酸盐结合态Cd、Pb和Zn残留量,从而削减矿山土壤和污染农田土壤中Cd、Pb和Zn总环境风险达50.81%和87.13%.亚氨基二琥珀酸可有效去除污染土壤中重金属并降低残留重金属的环境风险,是一种潜在材料可用于土壤重金属污染修复.  相似文献   
100.
Historically in developed countries, reported hepatitis E cases were typically travellers returning from countries where hepatitis E virus (HEV) is endemic, but now there are increasing numbers of non-travel-related (“autochthonous”) cases being reported. Data for HEV in New Zealand remain limited and the transmission routes unproven. We critically reviewed the scientific evidence supporting HEV transmission routes in other developed countries to inform how people in New Zealand may be exposed to this virus. A substantial body of indirect evidence shows domesticated pigs are a source of zoonotic human HEV infection, but there is an information bias towards this established reservoir. The increasing range of animals in which HEV has been detected makes it important to consider other possible animal reservoirs of HEV genotypes that can or could infect humans. Foodborne transmission of HEV from swine and deer products has been proven, and a large body of indirect evidence (e.g. food surveys, epidemiological studies and phylogenetic analyses) support pig products as vehicles of HEV infection. Scarce data from other foods suggest we are neglecting other potential sources of foodborne HEV infection. Moreover, other transmission routes are scarcely investigated in developed countries; the role of infected food handlers, person-to-person transmission via the faecal–oral route, and waterborne transmission from recreational contact or drinking untreated or inadequately treated water. People have become symptomatic after receiving transfusions of HEV-contaminated blood, but it is unclear how important this is in the overall hepatitis E disease burden. There is need for broader research efforts to support establishing risk-based controls.  相似文献   
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