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921.
基于位移设计的钢筋混凝土桥墩抗震性能试验研究(Ⅱ):振动台试验 总被引:1,自引:1,他引:0
通过模型振动台试验研究了基于位移设计的钢筋混凝土桥墩的抗震性能。以完成的拟静力试验中的桥墩试件为参考原型,利用基于位移抗震设计方法和现行桥梁抗震规范方法设计了4根1:2的钢筋混凝土桥墩试件并进行了模型振动台试验。对小震、中震和大震作用下桥墩试件的破坏形态、加速度和位移反应、位移延性系数和地震总输入能(耗能)等方面进行了比较分析。综合拟静力试验和振动台试验结果,可以认为基于位移设计的钢筋混凝土桥墩能够达到预期的延性抗震要求。 相似文献
922.
Granitic gneisses have been widely found in crystalline rocks in the Dinggye area of the Higher Himalaya (HHM) and the LhagoiKangri area of the North Himalaya (NHM), Tibet. In the HHM, the gneisses intruded in the granulite-amphibolite facies metamorphosed sedimentary rocks, known as Nyalam group. In the NHM, the gneisses intruded in the amphibolite facies metamorphosed ones, known as LhagoiKangri group. These granitic gneisses are peraluminous monzonitic granites in terms of their mineral assemblage, and are considered as being derived from metamorphosed sedimentary rocks by anatexis based on the transitional relationship of the gneisses with their migmatitized wall rocks. Zircons are similar in crystal shape and interior structure from both gneisses. Most of them are euhedral or subhedral elongated prism-shaped transparent crystals, with fine oscillatory zoning, showing the magmatic genesis. Some of them are short prism-shaped and with relict core inherited from magma source and oscillatory zoning mantle crystallized from magma. SHRIMP U-Pb dating of zicons shows that both the granitic gneisses in the HHM and NHM are Paleoproterozoic (1811.6±2.9 Ma and 1811.7±7.2 Ma, respectively). These ages are similar to those (1815 to 2120 Ma) from granitic gneiss which is widely distributed in the Lesser Himalaya (LHM). The ages of inherited zircons (>2493.9±7.0 Ma, 2095.8± 8.8 Ma, 1874±29 Ma) exhibit the possible presence of several thermal events in Paleoproterozoic. All of the ages suggest the same India basement beneath the different units in Himalaya area, and do not support the idea that the HHM and NHM are accretionary terranes in Pan-Africa orogenic event. The fact that the basement in HHM is as old as or even younger than LHM is inconsistent with the presently prevalent orogenic models such as either extrusion of low-viscosity mid-crust or orogenic channel. 相似文献
923.
924.
海水中铜离子对氨基酸—粘土体系液—固界面作用的影响 总被引:2,自引:0,他引:2
用E(%)-pH曲线法实验研究了海水中三元表面络合物的形成和构型。通过海水中金属铜离子对氨基酸—粘土界面作用的E(%)-pH曲线影响的研究,发现曲线具有“单向上移”的规律,表明甘氨酸、天冬氨酸—铜离子—高岭土三元体系在实验条件下主要形成(Ⅰ)型三元表面络合物即≡S—O—M—L。该系列论文另一部分已研究氨基酸对金属离子—粘土体系的影响,证明可形成(Ⅱ)型三元表面络合物即≡S—O—L—M。据此可以推测(Ⅰ)型和(Ⅱ)型在某一条件下可以转变构型,其中间构型可能即是Leckie等提出的环形三元表面络合物。 相似文献
925.
Several major inverse methods (Stommel-Schott method, Wunsch method, and Bernoulli method) have been successfully developed
to quantitatively estimate the geostrophic velocity at the reference level from hydrographic data. No matter the different
appeance, they are based on the same dynamical sophistication: geostrophy, hydrostatic, and potential density (ϱ) conservation
(Davis, 1978). The current inverse methods are all based on two conservation principles: potential density and potential vorticity
(q=f∂ϱ/∂z) and require β-turning. Thus, two necessary conditions can be incorporated into any inverse methods: (1) non-coincidence
of potential density and potential vorticity surfaces and (2) existence of vertical turning of the velocity (β-turning). This
can be done using the P-Vector, a unit vector in the direction of ▽ϱ×▽q (Chu, 1994, 1995). The first necessary condition becomes the existence of the P-vector, and the second necessary condition
leads to the existence of the P-vector turning in the water column. Along this line, we developed the P-vector inverse emthod
with a pre-requirement check-up. The method was verified in this study using the Modular Ocean Model (MOM) from Pacanowskiet al. (1991) version of Bryan-Cox-Semtner ocean general circulation model (OGCM), which is based on the work of Bryan (1969). The
statistically steady solutions of temperature and salinity from MOM are used as a “no-error data” set for computing absolute
geostrophic velocities by the P-vector inverse method. Circulations are similar between the MOM statistically steady solutions
and the P-vector solutions. Furthermore, the quantitative analysis shows that this inverse method has capability of picking
up the major signal of the velocity field. 相似文献
926.
对内蒙古测震台网2008年以来速报的346次地震(包括天然地震与爆破、塌陷)进行统计,以典型震例,分区域、分类别总结震相特征。在此基础上,讨论利用典型震例与波形互相关性在未来地震定位与震相精确识别方面应用的可能性,及利用非常规震相(sPn震相)准确测定震源深度的应用前景。通过以上分析,以期进一步提高内蒙古地震速报和编目工作质量。 相似文献
927.
A new species of Psychropotidae holothuroid, Benthodytes palauta sp. nov., was collected from the Kyushu-Palau Ridge at a depth of 2666 m. This new species is characterized by a leathery body wall, red-violet skin, five pairs of dorsal papillae, nineteen pairs of tube feet, and a narrow brim. The internal organs include one Polian vesicle, two tufts of gonads, and no respiratory trees. Ventral ossicles are large and spinous, with crosses of four arms with central bipartite apophyses. Papillae ossicles are crosses with four arms with bipartite apophyses. The dorsal ossicles were few and large, and cross-shaped with four arms and central bipartite apophyses. Tentacle ossicles were large and rod-shaped or slender rods. Gonad ossicles were primary crosses of four arms and brim ossicles were cross-shaped with spines. The phylogenetic analyses of this species support that B. palauta sp. nov. belongs to Benthodytes. Furthermore, the paraphyletic relationships were confirmed; however, a revision of the genus Benthodytes is needed to resolve its phylogenetic relationship. 相似文献
928.
929.
Uncontrolled discharges of municipal sewage, agricultural wastes and industrial effluents in the past decades have upset the ecosystems, caused frequent occurrences of red tides, and resulted in a loss of inland and coastal amenity values of the land-locked embayment of Tolo Harbour and the related river systems. This paper provides a review of the established relevant legislations and sewage management facilities for environmental conservation, and the current status of water environment in the Tolo Harbour Water Control Zone. 相似文献
930.
目前时程分析选波常采用目标谱法,即选择反应谱与目标谱有较好匹配的地震波。目前为止,关于在谱匹配中采用不同的坐标体系会给地震波缩放以及时程分析结果造成的差异性影响,还鲜有相关研究结果。本文旨在对比分析谱匹配中反应谱与目标谱采用算术值(算术坐标下ASM方法)和对数值(对数坐标下LSM方法)所得结构非线性时程分析结果的差异。以美国SAC Steel Project提出的3层、9层和20层钢框架结构为实例,以该计划提出的代表3种超越概率(即50年超越概率50%、10%和2%)的各组地震波平均反应谱作为目标谱,以这3组地震波(每组20条波)时程分析所得最大层间位移角的算术均值和几何均值作为目标反应,以简单地震信息初选的小型地震波数据库(共40条波)作为备选波,将ASM和LSM方法优选出的7条地震波所得时程分析结果进行了差异性分析。研究表明, LSM方法所得地震波的缩放系数明显大于ASM方法,并且地震波的排序即选择结果也存在一定差异。ASM和LSM方法对结构反应均值(算术均值和对数均值)估计的准确度均控制在±20%以内,但LSM方法所得结构反应更大。LSM方法在降低结构反应离散性方面较ASM方法更有优势,且对于较长周期结构(如20层结构)及结构非线性程度较高(如50年超越概率10%、2%)时,这种优势会更为凸显。 相似文献