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901.
C.A.Greated 《中国海洋工程》1997,(4)
-Force measurements of oscillatory flow acting on a single circular cylinder have been carriedout.The experiments were done by oscillating a circular cylinder in still water.Instantaneous forces and ve-locity fields around the cylinder were measured by Particle Image Velocimetry(PIV).The Keulegan-Car-penter number(KC)varied in the range from 5 to 20 and the viscous parameter β=Re/KC was set at500(Re is Reynolds number).It was found that the strength and frequency of the lift force increased withKC number,the main frequency of the lift force being three times the frequency of the oscillatory flow atKC=20.The movement and strength of the vortices around the cylinder are discussed for differentKC numbers. 相似文献
902.
Glass(1967)在深海岩心中发现的微玻陨石,根据其地层位置和地理产状,已经被用于将玻陨石和微玻陨石建立起一个成因上的联系,这一点已被其化学性质进一步证实.澳大利亚微玻陨石分布区与布容/松山地磁倒转范围明显有关,由于澳大利亚撞击事件只是瞬时过程,表示的是瞬间的地质记录,所以微玻陨石用于沉积物再生的标志。 相似文献
903.
水淹和盐度,在海岸地带是两个同等重要的问题。目前还没有一种精确的遥感技术可以用来对受这两个因素影响的地带制图。为了研究采用微波辐射计进行这种制图的可行性,我们通过能够反映水淹区和盐渍区特性的层化模型,进行了亮度温度的数值计算。亮度温度的特性可以显示出水淹区和盐渍区的特征值。本文所提供的结果表明了微波辐射计在对水淹区和盐渍区制图方面的应用价值。 相似文献
904.
Matthiessen P Allen Y Bamber S Craft J Hurst M Hutchinson T Feist S Katsiadaki I Kirby M Robinson C Scott S Thain J Thomas K 《Marine environmental research》2002,54(3-5):645-649
This paper summarises results of the EDMAR programme which is investigating oestrogenic and androgenic endocrine disruption in UK coastal waters. Most of the data concern fish. Four species (flounder, viviparous blenny and two sand gobies) are experiencing feminisation in industrialised estuaries. In males this includes vitellogenin (VTG) synthesis, ovotestis induction and/or feminised sexual characteristics. Although reproductive success may be impaired in some cases, implications for fish populations are still unclear. Suspected causative contaminants include natural oestrogenic substances and synthetic oestrogen mimics. The majority of the oestrogenic activity is adsorbed to sediments, and routes of exposure may include benthic food chain transfer. Some natural androgenic substances are also being discharged to estuaries, but their activity appears low. 相似文献
905.
906.
由来自9个国家的科学家组成的研究队为研究哥斯达黎加外的活动大陆边缘在圣地亚哥登上了“JOIDES决心”号大洋钻探船.这些科学家将确定该处岩石和沉积物的年龄、物理化学性质,并将利用新开发的被称作‘随钻测井”(LWD)的测井工具.LWD技术可在钻井施工的同时在钻孔中适当的位置测量物理化学性质,并给出不受钻孔中钻具垂直运动影响的原始结果.该研究队由EliSlyer博士(加里福尼亚大学大地构造研究所所长)和GakuKimura博士(日本大皈大学地球科学系主任)领导,其他科学家分别来自美国、日本、法国、德国、大不列颠、加拿大、意… 相似文献
907.
海平面相对变化和气候变化之间的关系——以美国西部宾夕法尼亚—二叠纪碳酸盐—硅质碎屑岩混合岩层为例EugeneC.Rankey为了使海平面相对变化和气候变化模式广泛采用,下面几个条件必须满足:第一,海平面升降变化必须与气候变化同步;第二,地形或沉积对气... 相似文献
908.
Mitrovic SM Hamilton B McKenzie L Furey A James KJ 《Marine environmental research》2005,60(3):397-401
The change in concentration of the disulfated polyether yessotoxin (YTX) produced by a culture of the marine dinoflagellate Protoceratium reticulatum was measured in laboratory experiments under light and dark conditions. Experimental cultures were inoculated and grew at a growth rate of 0.14 d(-1) until stationary phase was reached, after approximately 21 days. Cultures were maintained in the stationary phase until 31 days after inoculation. Cells of P. reticulatum contained a concentration of approximately 10-15 pg YTX cell(-1) during stationary phase but this was considerably lower (<5 pg cell-1) during the growth phase. Low amounts of 45-hydroxy-YTX were also detected. At day 32, P. reticulatum was killed by cooling to 1 degrees C (confirmed microscopically) and YTX concentrations were measured periodically under light and dark conditions. YTX concentrations decreased rapidly to approximately 10% of the initial concentration within the first 3 days and depleted to near zero within a week in the light treatment. In the dark environment, YTX persisted longer with approximately 10% of the initial YTX concentration still remaining after 18 days. 相似文献
909.
英国气象局的业务波浪预报模式是在网格点上给出浪场。这个浪场通常定义在地球表面的极地侧射投影上。该模式可以把任意的网格长度、任意形状或尺寸的海洋区域初始化,但必须受到机器内存的限制。这一模式有总体的联结能力,即允许任何模式从其它模式中获得流入边界条件。实际操作中分两个模式运行。一个覆盖了北半球大部分区域,在60°N处其网格长度为300公里。它为欧州西北大陆架53公里网格长度的模式提供了边界条件。该模式的详细描述由Golding(1983)给出。此模式以离散谱给出每个网格点上的浪场,谱的分辨率是可变的,目前包括12个方位(以30°为间隔)和11个频率段(0.05、0.06、0.072、0.086、0.104、0.124、0.148,0.178、0.214、0.256、0.308Hz)所组成的波。另外,模式还包括了浅水效应,其计算水深间隔为2米,并包括可变群速、折射和底部摩擦影响。这些因素对北海和英吉利海峡的计算结果有显著的影响。 相似文献
910.
Camus L Jones MB Børseth JF Grøsvik BE Regoli F Depledge MH 《Marine environmental research》2002,54(3-5):425-430
Industrial activities, notably oil and gas industries, are expanding in the Arctic. Most of the biomarkers were developed using temperate organisms living at temperatures above 10 degrees C. Little is known about the biomarker responses of organisms living between -1.88 and 5 degrees C. Therefore, assessment of the toxicity of chemicals to cold-water adapted species is required. In this study, the Arctic scallop, Chlamys islandicus, was selected as a key species for bio-monitoring because of wide distribution in Arctic waters and its commercial value. Test animals, stored in seawater at 2 degrees C, were injected with benzo(a)pyrene (diluted in cod liver oil 5 mg ml(-1)) in the adductor muscle every 24 h for four days giving a final dose of 0, 74 and 90.6 mg kg(-1) wet weight for control, low and high dose, respectively. The biomarkers used were total oxyradical scavenging capacity (TOSC) in the digestive gland and cell membrane stability of haemocytes. TOSC values were significantly reduced (ca. 30%) in exposed groups (P < 0.05), indicating a depletion in oxyradical molecular scavengers. The antioxidant defences appeared to be overwhelmed by the reactive oxygen species as the plasma membranes of haemocytes were destabilised (P < 0.05) probably due to lipid peroxidation. These data indicate that reactive oxygen species (ROS) were produced by Arctic scallops via the metabolisation of benzo(a)pyrene at 2 degrees C. 相似文献