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921.
Y. M. Zhao C. L. Duan L. L. Wu H. J. Zhang J. F. He Y. Q. He 《International Journal of Environmental Science and Technology》2012,9(4):719-728
Research on recycling waste printed circuit boards is at the forefront of preventing environmental pollution and finding ways to recycle resources. A wet process for reclaiming metals from printed circuit boards applying a tapered diameter separation bed is described, and the separation mechanism of the device is proposed. The motion of a particle in the tapered diameter fluid flow field and particle separation within this field were studied. As the material passes through the fluid field, along with the water, differences in particle density, granularity, and shape cause particles to follow at different trajectories. A tapered diameter separation bed was used to process 1?C0.074?mm-sized crushed material from discarded printed circuit boards. The separation efficiency of 91.77?% and the recovery rate of 95.79?% for recovered metal were achieved with a discharge water flow rate of 4.5m3/h, a material feed rate of 300?g/min, and an obliquity of 30°. For ?0.074?mm printed circuit boards, the metal recovery is 93.42?% and the separation efficiency is 77.63?% when the water discharge is 2?m3/h, the obliquity is 35o, and the material feed rate is 450?g/min. The superfine products in a size range of ?0.074?mm can be recovered effectively under suitable operating condition using the tapered diameter separation bed. It indicates that the lower separation limit of the tapered diameter separation bed can be close to zero. The technique will prevent environmental pollution from waste printed circuit boards and allow efficient recovery. 相似文献
922.
兰州市大气飘尘的有机地球化学研究--Ⅱ.酮和醇脂类化合物的组成和分布特征 总被引:6,自引:0,他引:6
首次对兰州市大气飘尘中酮和醇脂类化合物进行了分析和研究。结果表明,兰州市大气飘尘中正烷基2酮和直链烷基醇的浓度分别为20~270ngm-3和520~910ngm-3,并表现为3月份高于7月和8月份,这与兰州市特殊的地形和气候条件有关;其分布特征指示了它们来自人为活动、微生物和现代高等植物,而且它们在这3种来源中所占的比例分别为2.8%~19.7%、15.4%~34.6%和50.3%~81.8%。甾醇化合物的浓度很低,它们由现代生物所提供。丰富的C18类异戊二烯酮化合物的存在,反映了大气飘尘中有机质在大气氧化过程中已经被改造。 相似文献
923.
在我国“三北”地区,浅层地下水中高氟苏打水分布广泛。本文利用和简化了Helgeson风化模型,以吉林省乾安地区为例,对含氟初始风化水化学组成作了研究和计算:探讨了二氧化碳滴定作用对风化过程的影响,从而定量确定了高氟水的成因模型。 相似文献
924.
925.
论德尔尼黄铁矿型铜钴矿床的成矿规律 总被引:10,自引:2,他引:10
区域深断裂带(即昆南深断裂)控制着华力西期超基性岩和印支期花岗岩的分布。由于花岗岩的成矿作用,并在构造及岩性圈闭条件下,形成了德尔尼黄铁矿型铜钴矿床。上石炭统的下部片岩组含矿性较好,是区内矿源层之一,但矿质主要来自花岗岩岩浆热液。该矿区属浅成热液矿床 相似文献
926.
1 地质概况及矿体特征金川铜镍硫化物矿床产于金川岩体中。金川岩体为一超基性岩体,侵入于下元古界白家嘴子组,直接与片麻岩、蛇纹大理岩、条带均质混合岩接触,呈不规则岩墙状产出,长约6500m,宽约20~527m,垂直延深达1100m,出露面积为1-34km2。与成矿关系密切的岩石主要有二辉橄榄岩、橄榄二辉岩、含辉橄榄岩、纯橄岩等,一般基性程度越高,含矿性越好。该岩体被北东东向断裂分割为四段,每一段都有矿体产出,与围岩之间有接触交代作用。本文所研究的富铜矿体产在金川龙首矿区东采区,位于1160~14… 相似文献
927.
928.
土壤对重金属离子的吸附容量明显受阴离子配位体的影响。本文通过试验探讨了Cl~(-),SOi_4~(2-)HCO_3~(-)阴离子在不同的pH值条件下,分别对土壤吸附铜的干扰规律。运用反求吸附参数法评价了不同阴离子对铜吸附量的干扰程度,论证了土壤与地下水之间元素迁移的规律。 相似文献
929.
The concentrations, fluxes, enrichments and chronologies of potential harmful elements in sediment cores from Bohai Bay, North China 总被引:2,自引:0,他引:2
To reflect the historical changes, the vertical profiles of concentrations, enrichment factors and burial fluxes of potential
harmful elements (PHEs: Ga, Ge, Mo, In, Sn, Sb, Te, Tl, Bi, W and V) were determined in two sediment cores collected from
Bohai Bay. Sediment accumulation rates and chronologies were obtained from 210Pb activity-depth profiles. Two sediment accumulation rates in core 2 were observed: a higher rate of 4.78 mm/year before
the 1960s and 2.93 mm/year since then. The sediment accumulation rate in core 6 was 2.82 mm/year. The PHE concentrations and
burial fluxes exhibited an obvious variation with the depth due to the natural and anthropogenic inputs. Especially, the higher
concentrations and burial fluxes of PHEs occurred in the 1960s and 1980s, matching the large runoff and industrial development.
Enrichment factors (EFs) of PHEs were computed in order to evaluate their potential sources. Results showed that the EFs of
Sb, Te and Bi were higher than 1.5, revealing the anthropogenic inputs; however, the EFs of other PHEs were lower than 1.0,
indicating the natural inputs. Moreover, the high EFs of Sb, Te and Bi appeared in the surface or subsurface layers, indicating
that the extent of anthropogenic contamination enhanced in recent years. Sequential extraction technique was used to study
the ecological risks of PHEs. Results revealed that the ecological risks of Mo, Te and Bi in both cores and Sb and W in core
2 were medium due to their high availability in the exchangeable and carbonate-bound fractions. 相似文献
930.