全文获取类型
| 收费全文 | 1100篇 |
| 免费 | 218篇 |
| 国内免费 | 97篇 |
专业分类
| 测绘学 | 15篇 |
| 地球物理 | 424篇 |
| 地质学 | 860篇 |
| 海洋学 | 22篇 |
| 天文学 | 7篇 |
| 综合类 | 25篇 |
| 自然地理 | 62篇 |
出版年
| 2023年 | 4篇 |
| 2022年 | 23篇 |
| 2021年 | 17篇 |
| 2020年 | 34篇 |
| 2019年 | 41篇 |
| 2018年 | 30篇 |
| 2017年 | 43篇 |
| 2016年 | 33篇 |
| 2015年 | 33篇 |
| 2014年 | 72篇 |
| 2013年 | 30篇 |
| 2012年 | 47篇 |
| 2011年 | 82篇 |
| 2010年 | 43篇 |
| 2009年 | 90篇 |
| 2008年 | 86篇 |
| 2007年 | 72篇 |
| 2006年 | 71篇 |
| 2005年 | 41篇 |
| 2004年 | 48篇 |
| 2003年 | 39篇 |
| 2002年 | 38篇 |
| 2001年 | 29篇 |
| 2000年 | 28篇 |
| 1999年 | 34篇 |
| 1998年 | 35篇 |
| 1997年 | 31篇 |
| 1996年 | 36篇 |
| 1995年 | 26篇 |
| 1994年 | 26篇 |
| 1993年 | 25篇 |
| 1992年 | 18篇 |
| 1991年 | 12篇 |
| 1990年 | 19篇 |
| 1989年 | 10篇 |
| 1988年 | 16篇 |
| 1987年 | 8篇 |
| 1986年 | 8篇 |
| 1985年 | 7篇 |
| 1984年 | 8篇 |
| 1983年 | 3篇 |
| 1982年 | 5篇 |
| 1981年 | 1篇 |
| 1980年 | 1篇 |
| 1979年 | 1篇 |
| 1978年 | 5篇 |
| 1977年 | 1篇 |
| 1976年 | 1篇 |
| 1975年 | 1篇 |
| 1954年 | 3篇 |
排序方式： 共有1415条查询结果，搜索用时 15 毫秒
81.
82.
云南绿春咪霞金矿成矿地质条件 总被引：1，自引：0，他引：1
咪霞金矿赋存在多元素高背景值下志留统薄层状蚀变板岩中,受北西向F6-1断裂及正长岩、煌斑岩控制,与多元素异常、黄铁矿化等多种围岩蚀变对应,具较好的成矿地质条件。 相似文献
83.
84.
通过对郑州市城区深部基岩层热储的岩性、构造、热源及盖层条件分析研究,总结了该区热储特征,并首次提出了断裂循环型带状热储构造网络体系的构思,这对该区今后深部基岩层热储的研究具有一定的参考意义。 相似文献
85.
The energy balance of a solid subject to fracture has been explored using heat and mass transfer equations with regard to the volumetric and superficial components. In the suggested model, brittle fracture of a cracked solid considered as a heterogeneous two-phase medium is described by an equation analogous to the Griffith’s criterion for propagation of a single crack. The derived equation is used, together with estimates of relative change in specific interface area, to study the respective change of free strain energy and pressure in rocks associated with failure. 相似文献
86.
This paper presents an application of rock engineering system (RES) in an attempt to reveal and assess the inherent instability
potential of 388 sites where equivalent landslides have been manifested and recorded in the region of Karditsa County, Greece.
The main objective has been defining the principal causative and triggering factors responsible for the manifestation of landslide
phenomena, quantify their interactions, obtain their weighted coefficients, and calculate the instability index, which refers
to the inherent potential instability of each natural slope of the examined region. From the statistical interpretation of
the data reported in a well-documented database and concerning the examined failure sites, a clear correlation between the
instability index and the area affected by a single landslide event has been revealed. Almost the entire failure sites, 98%
of the examined slope sites, exhibit an instability index value over 55, a value which is thought to be a critical threshold
for landslide manifestation concerning natural slopes in Karditsa County. It is argued that the presented RES methodology,
engaging the selected set of parameters, could be considered as an effective expert's tool for ranking, in an objectively
optimal and simple way, the instability potential of natural slopes in Karditsa County, and thus providing a tool for sound
zoning landslide hazard. 相似文献
87.
Sealing layers are often represented by sedimentary sequences characterized by alternating strong and weak lithologies. When involved in faulting processes, these mechanically heterogeneous multilayers develop complex fault geometries. Here we investigate fault initiation and evolution within a mechanical multilayer by integrating field observations and rock deformation experiments. Faults initiate with a staircase trajectory that partially reflects the mechanical properties of the involved lithologies, as suggested by our deformation experiments. However, some faults initiating at low angles in calcite-rich layers (θi = 5°–20°) and at high angles in clay-rich layers (θi = 45°–86°) indicate the important role of structural inheritance at the onset of faulting. With increasing displacement, faults develop well-organized fault cores characterized by a marly, foliated matrix embedding fragments of limestone. The angles of fault reactivation, which concentrate between 30° and 60°, are consistent with the low friction coefficient measured during our experiments on marls (μs = 0.39), indicating that clay minerals exert a main control on fault mechanics. Moreover, our integrated analysis suggests that fracturing and faulting are the main mechanisms allowing fluid circulation within the low-permeability multilayer, and that its sealing integrity can be compromised only by the activity of larger faults cutting across its entire thickness. 相似文献
88.
Triaxial shear tests are performed to assess the effects of displacement velocity and confining pressure on shear strengths and dilations of tension-induced fractures and smooth saw-cut surfaces prepared in granite, sandstone and marl specimens. A polyaxial load frame is used to apply confining pressures between 1 and 18 MPa with displacement velocities ranging from 1.15 × 10−5 to 1.15 × 10−2 mm/s. The results indicate that the shearing resistances of smooth saw-cut surfaces tend to be independent of the displacement velocity and confining pressure. Under each confinement the peak and residual shear strengths and dilation rates of rough fractures increase with displacement velocities. The sheared-off areas increase when the confining pressure increases, and the displacement rate decreases. The velocity-dependent shear strengths tend to act more under high confining pressures for the rough fractures in strong rock (granite) than for the smoother fractures in weaker rocks (sandstone and marl). An empirical criterion that explicitly incorporates the effects of shear velocity is proposed to describe the peak and residual shear strengths. The criterion fits well to the test results for the three tested rocks. 相似文献
89.
This paper aims at developing a method for modeling rock mass with preexisting multiple discontinuities within the framework of the smoothed finite element method (SFEM). The discontinuity is simulated by an interface element with zero thickness, the stiffness matrix of which are derived explicitly based on the SFEM. An elastic damage constitutive relation with residual strength is introduced in order to describe the nonlinear mechanical behavior of the discontinuities. The computation codes of the present method were developed. The present method has been verified to be a sound approach for modeling discontinuous rock mass, inheriting the advantages of the SFEM. 相似文献
90.