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141.
Adsorption by nanoporous media is critically involved in many fundamental geological and geochemical processes including chemical weathering,element migration and enrichment,environmental pollution,etc.Yet,the adsorption behavior of metal ions on nanoporous materials has not been systematically investigated.In this study,MCM-41 material with a monodisperse pore size(4.4 nm)and a large BET specific surface area(839 m^2/g)was hydrothermally prepared and used as a model silica adsorbent to study the adsorption characteristics of Cu^2+as a representative metal ion.The Cu^2+adsorption capacity was found to increase with increasing suspension pH in the range from 3 to 5 and to decrease in the presence of NaNO3.At 25℃,pH=5,and a solid-to-liquid ratio of 5 g/L,the adsorption capacity was determined to be 0.29 mg/g,which can be converted to a dimensionless partition coefficient of 45,indicating a strong enriching effect of nanoporous silica.The adsorption isotherm and kinetic data were fitted to several commonly used thermodynamic,kinetic,and diffusion models.The adsorption mechanism was also studied by Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy and synchrotron-based X-ray absorption spectroscopy.The results suggest that Cu2+ion adsorption is an entropy-driven endothermal process,possibly involving both outer-sphere and inner-sphere complexes.  相似文献   
142.
C10TAB,C14TAB,C18TAB柱撑蒙脱石层间域有机柱排布研究   总被引:7,自引:2,他引:5  
用十烷基三甲基溴化铵(C10TAB)、十四烷基三甲基溴化铵(C14TAB)和十八烷基三甲基溴化铵(C18TAB)制备有机柱撑蒙脱石,并对产物进行X射线衍射表征。研究结果表明:柱化剂的浓度和烷基季铵离子的性质能影响烷基季铵离子在蒙脱石层间的排布模式。在柱化剂浓度较低时易形成平卧排列,柱化剂达到一定浓度时石蜡型结构方能形成,且直链烷基越长,烷基季铵离子在蒙脱石层问越易形成石蜡型倾斜排列。在平卧结构向石蜡型结构转化过程中可出现多种排列共存。  相似文献   
143.
4A沸石吸附模拟核素Sr,Cs后的组分变化和结构表征   总被引:6,自引:2,他引:4  
通过4A沸石吸附模拟核素Sr,Cs前后的化学成分分析、X衍射分析和红外光谱分析等手段方法,分析探讨了模拟核紊Sr,Cs在4A沸石的赋存状态,结果表明:4A沸石与模拟核素Sr,Cs之间主要以离子交换的方式发生作用,Sr^2 ,Cs^ 取代4A沸石中的可交换离子Na^ ,占据4A沸石a笼中的6元环和8元环。导致4A沸石的晶胞参数增大,晶格发生畸变。  相似文献   
144.
大气气溶胶中若干有机物的含量和季节变化   总被引:4,自引:2,他引:2  
研究、探讨青岛近岸大气气溶胶中多芳烃类化合物的浓度水平、变化特征及影响因素。用高效液相色谱荧光检测法分析了青岛近岸大气气溶胶中的多环芳烃(PAHs)的含量水平,共检出13种多环芳烃化合物。结果表明该类化合物总量(∑PAHs)具有明显的季节特征,呈现春季<秋季<冬季的特征,人类活动可能是其主要来源。  相似文献   
145.
介绍了采用测边三角网和GPS静态测量实施三峡工程加密控制网的应用情况,阐述了随着光电测距精度的不断提高及水电施工环境的影响,采用测边网加测距三角高程网实施控制网加密是当前行之有效的一种好方法;此外,GPS测量以其限定条件少、操作简单、高自动化的内业处理等优点为施工控制测量开辟了一条新途径。  相似文献   
146.
Five new biotite reference materials were calibrated at the SwissSIMS laboratory (University of Lausanne) for oxygen isotope determination by secondary ion mass spectrometry (SIMS) and are available to the scientific community. The oxygen isotope composition of the biotites, UNIL_B1 to B5, was determined by laser‐heating fluorination to be 11.4 ± 0.11‰, 8.6 ± 0.15‰, 6.1 ± 0.04‰, 7.1 ± 0.05‰ and 7.6 ± 0.04‰, respectively. SIMS analyses on spots smaller than 20 μm gave a measurement repeatability of 0.3‰ (2 standard deviation, 2s). The matrix effect due to solid solution in natural biotite could be expressed as a linear function of XMg and XF for biotite. No effect was found for different crystallographic orientations. SIMS analysis allows the oxygen isotope composition of biotite to be measured with a measurement uncertainty of 0.3–0.4‰ (2s) for biotites with similar major element compositions. A measurement uncertainty of 0.5‰ (2s) is realistic when F poor biotites (lower than 0.2% m/m oxides) within the compositional range of XMg of 0.3–0.9 were compared from different sessions. The linear correlation with F content offers a reasonable working curve for F‐rich biotites, but additional reference materials are needed to confirm the model.  相似文献   
147.
利用离子色谱法对水中常见的7种阴离子进行定性和定量的分析,在既定的条件下,分别建立校正曲线法(外标法)及单点校正法模板,并对温泉水样校正分析。结果显示,外标法测得离子数据较为平稳,相对偏差均小于5%,适用于观测温泉水中其含量的变化。  相似文献   
148.
Crude oil hydrocarbon composition characteristics and oil viscosity prediction are important bases in petroleum exploration.A total of 54 oil/heavy-oil samples and 17 oil sands were analyzed and quantified using both comprehensive 2D gas chromatography(GC×GC)and comprehensive 2D gas chromatography/time-of-flight mass spectrometry(GC×GC/TOFMS).The results show that crude oil in the West slope is mainly heavy oil and its hydrocarbon composition is characterized overall by paraffinsmono-aromaticsnaphthenesnon-hydrocarbonsdi-aromaticstri-aromaticstetra-aromatics.Aromatics are most abundant and non-hydrocarbons are least abundant,whilst content differences among paraffins,naphthenes,aromatics,and non-hydrocarbons are less than 15%.There are two types of heavy oil,secondary type and mixing type.Biodegradation is the main formation mechanism of heavy oil.Biodegradation levels cover light biodegradation,moderate biodegradation,and severe biodegradation.With increasing biodegradation,paraffin content decreases while contents of aromatics and nonhydrocarbons increase.In contrast,naphthene content increases first and then decreases with increasing biodegradation.In severe biodegradation stage,naphthenes decrease more quickly than aromatics and non-hydrocarbons.This provides a new method for studying oil/heavy-oil biodegradation mechanism and biodegradation resistance of different hydrocarbons at different biodegradation stages.In the Longhupao-Daan terrace and Qijia-Gulong depression,most crude oil is conventional oil.Its composition is dominated by paraffins with the lowest content of aromatics.In some casual oil wells from the Longhupao-Daan terrace,crude oil from Saertu oil reservoirs is moderately biodegraded whereas crude oil from Putaohua oil reservoir is lightly biodegraded.Chemical parameters using saturate hydrocarbons and aromatics are usually not suitable for determining organic type and thermal maturity of biodegraded oil,especially of moderately or severely biodegraded oil,whilst Ts/(Ts+Tm)ratio can be used to determine thermal maturity of both conventional crude oil and heavy oil.  相似文献   
149.
In this study, soil samples collected from the sides of two streams with high debris flow potential at Shenmu and Fengchiou village in Nantou County, Taiwan, were used for seepage tank tests in the laboratory. While the tests were being conducted, observations were made to investigate the relationships among displacement of the slope, quality of the seepage water and occurrence of mass movement. The results showed that according to the change rate, displacement could be divided into two stages, namely, the initial failure displacement stage and primary failure displacement stage. While the displacement of the slope was in primary failure displacement stages, the probability of slope failure became much higher. Before general slope failure, electrical conductivity (EC) and sulfate ion (SO4 2−) concentration of the seepage water increased significantly. The time when EC of the seepage water started to increase rapidly was much earlier than that when displacement of the slope started to increase significantly. Therefore, from the hazard mitigation view, there will be a longer time for response if EC of the seepage water was monitored.  相似文献   
150.
塔里木河中游输水堤防的修建对地下水化学特征的影响   总被引:5,自引:1,他引:4  
通过对塔里木河中游输水堤防修建后,沙子河口、乌斯满和阿其河口三个断面地下水化学特征自2001—2003年的时空变化的监测与分析,初步揭示了在输水堤防影响下地下水化学特征变化的初步规律,结果表明:在空间上,沙子河口断面地下水化学变化规律完全被颠倒过来,乌斯满断面,地下水化学变化规律受输水堤防的影响不十分明显,但地表积盐严重,阿其河口断面,则呈现复杂的变化;在时间上,丰枯期地下水化学特征的正常变化规律在沙子河口被彻底改变,在乌斯满和阿其河口呈现出复杂变化。由于地下水循环具有潜在性和迟滞性,要彻底揭示在输水堤防影响下地下水化学特征时空变化的规律,需要进一步跟踪监测研究。  相似文献   
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