全文获取类型
收费全文 | 206篇 |
免费 | 3篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 4篇 |
大气科学 | 28篇 |
地球物理 | 45篇 |
地质学 | 83篇 |
海洋学 | 1篇 |
天文学 | 41篇 |
综合类 | 5篇 |
自然地理 | 6篇 |
出版年
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 3篇 |
2013年 | 5篇 |
2012年 | 8篇 |
2011年 | 6篇 |
2010年 | 5篇 |
2009年 | 6篇 |
2008年 | 15篇 |
2007年 | 8篇 |
2006年 | 7篇 |
2005年 | 3篇 |
2004年 | 6篇 |
2002年 | 2篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1974年 | 1篇 |
1973年 | 5篇 |
1972年 | 3篇 |
1971年 | 4篇 |
1970年 | 3篇 |
1969年 | 1篇 |
排序方式: 共有213条查询结果,搜索用时 46 毫秒
21.
Anharmonic oscillations of rotating stars have been studied by various authors in literature to explain the observed features of certain variable stars. However, there is no study available in literature that has discussed the combined effect of rotation and tidal distortions on the anharmonic oscillations of stars. In this paper, we have created a model to determine the effect of rotation and tidal distortions on the anharmonic radial oscillations associated with various polytropic models of pulsating variable stars. For this study we have used the theory of Rosseland to obtain the anharmonic pulsation equation for rotationally and tidally distorted polytropic models of pulsating variable stars. The main objective of this study is to investigate the effect of rotation and tidal distortions on the shapes of the radial velocity curves for rotationally and tidally distorted polytropic models of pulsating variable stars. The results of the present study show that the rotational effects cause more deviations in the shapes of radial velocity curves of pulsating variable stars as compared to tidal effects. 相似文献
22.
A total of 81 samples (244 specimens) from Upper Cretaceous Indus Molasse and Middle to Upper Cretaceous Dras Flyschoids of the Indus-Tsangpo suture zone in Ladakh (northwest Himalaya) has been studied by thermal demagnetization methods.Both formations showed a characteristic magnetization component indicative for equatorial to low northern palaeolatitudes of acquisition. Similar palaeolatitudes have been obtained before from secondary magnetization components of Early Tertiary age in the Ladakh Intrusives and in the Tibetan Sedimentary Series of central Nepal. The present characteristic components are interpreted likewise as secondary magnetizations which stabilized between 50 and 60 m.y. ago, during Greater India's collision with Asia's southern margin.The Dras Flyschoids show another magnetic component which, in case of primary origin, indicates acquisition at a low southern palaeolatitude. If correct, this interpretation supports recent suggestions for Late Cretaceous obduction of an island arc on Greater India's northern margin. 相似文献
23.
24.
25.
Devendra Lal 《Meteoritics & planetary science》2008,43(11):1909-1909
26.
Priyanka Lal Vishnu Agarwal Parul Pruthi Swaranjit Singh Cameotra Vikas Pruthi 《洁净——土壤、空气、水》2008,36(12):963-968
The microbiological assessment of biofilm formation from paper mill effluent discharged through a pipeline revealed a maximum microbial count for Pseudomonas (5·106 cfu/mL) followed by Staphylococcus (4·106 cfu/mL), Bacillus (8.2·105 cfu/mL), Burkholderia (7.2·105 cfu/mL), Enterobacter (5.3·104 cfu/mL), Acinetobacter (4.1·103 cfu/mL), Alcaligenes (1.2·102 cfu/mL) and Klebsiella (0.8·102 cfu/mL) species. Among these species, the maximum biofilm formation was observed after 24 h of incubation by Pseudomonas sp. using a crystal violet (CV) assay. This isolate was later identified by 16S rRNA amplification to be Pseudomonas aeruginosa PME1. Extracellular polymeric substances (EPS) of P. aeruginosa PME1 in the biofilm showed a reduction in total carbohydrate content (42%) with increased protein (9.0%), hexosamine (3.0%) and uronic acid (1.7%) content as compared to its planktonic form. Antimicrobial susceptibility testing revealed that P. aeruginosa PME1 biofilms were 17, 24, 27, 30, and 32 times more resistant to cefotaxime, imipenem, ceftazidime, tazobactam and piperacillin, respectively, than their free flowing counterparts. 相似文献
27.
Prof. Dr. M. Raith Dr. P. Raase Dr. D. Ackermand Dr. R. K. Lal 《International Journal of Earth Sciences》1982,71(1):280-290
The Archaean craton of southern India is characterized by a highly complicated and not yet fully understood geological history comprizing several cycles of sedimentation and volcanism, deformation and metamorphism in the span between about 3400 and 2500 m. y. The large scale regional variation in metamorphic grade observed today is essentially related to a metamorphic event at about 2600 m. y. ago which affected an older migmatite, gneiss-greenstone terrain (2900–3400 m. y.).The southern area is characterized by granulite facies (700–750° C/8–10 kb). An extensive charnockite-khondalite belt has been generated by atectonic transformation of the migmatite-gneiss terrain through the influx of a CO2-rich fluid. Towards the north of the terrain the metamorphic grade decreases to amphibolite facies (600° C/6–8 kb) and to greenschist facies (400° C) which is restricted to the Dharwar greenstone belts. Metamorphism related to younger shear zones in the southern part of the craton led to retrogression of the charnockite-khondalite series under conditions of amphibolite to greenschist facies.The P-T conditions of metamorphism have been evaluated applying mineral stability data and methods of geothermometry and geobarometry in an area between Shimoga-Chitradurga (North) and Coimbatore-Karur (South).
The present study is part of a joint project of Benaras Hindu University at Varanasi and University of Kiel. Financial Support by the Deustche Forschungsgemeinschaft is gratefully acknowledged.
We especially thank M. N. Viswanatha, Geological Survey of India, for his cooperation during the field work. 相似文献
Zusammenfassung Der archaische Kraton Südindiens ist durch eine komplexe, noch nicht vollständig aufgeklärte geologische Entwicklungsgeschichte gekennzeichnet. Sie umfaßt mehrere Zyklen von Sedimentation und Vulkanismus, Deformation und Metamorphose in der Zeitspanne von etwa 3400 bis 2500 Ma. Die großregionale metamorphe Zonierung wird im wesentlichen als das Ergebnis eines Metamorphose-Ereignisses vor ca. 2600 Ma angesehen, das den gesamten archaischen Komplex aus granitoiden Gneisen, Migmatiten und Greenstone-Serien erfaßte.Das südliche Gebiet ist durch Bedingungen der Granulitfazies (700–750° C/8–10 kb) charakterisiert. Hier entstand eine ausgedehnte Charnockit-Khondalit-Zone durch post-tektonische Umwandlung der Migmatit-Gneisserien infolge Zufuhr einer CO2-reichen fluiden Phase. Nach Norden zu nimmt der Metamorphosegrad bis zur niedrigtemperierten Amphibolitfazies (600° C/6–8 kb) und in den Dharwar-Greenstone Belts sogar bis zur Grünschieferfazies (400° C) ab.Eine jüngere Metamorphose von Amphibolit-bis Grünschieferfazies ist auf proterozoische Scherzonen beschränkt. Im südlichen Gebiet führte sie zu einer örtlich unterschiedlich intensiven retrograden Überprägung der Charnockit-Khondalit-Serie.Die P-, T-Bedingungen der Regionalmetamorphose wurden anhand von Mineralstabilitätsdaten und mit Methoden der Geothermometrie und Geobarometrie für das Gebiet zwischen Shimoga-Chitradurga (Norden) und Coimbatore-Karur (Süden) abgeleitet.
Résumé Le craton archéen de l'Inde méridionale est caractérisé par une évolution géologique complexe et mal connue. Elle comprend plusieurs cycles de sédimentation et de volcanisme, de déformation et métamorphisme d'une durée d'environ 3400 jusqu'à 2500 Ma.La variation du degré de métamorphisme observée aujourd'hui est considérée comme le résultat d'un épisode de métamorphisme datant d'environ 2600 Ma, qui a affecté l'ensemble du domaine archéen composé de granitoïdes et de ceintures de roches vertes.La région méridionale de craton est caractérisée par le faciès granulite (700–750 °C/ 8–10 kb). Une zone étendue de charnockites et khondalites est le produit d'une transformation postdéformative résultant de l'apport d'une phase fluide riche en CO2. Vers le nord le degré de métamorphisme décroit jusqu'au faciès amphibolites (600 °C/6–8 kb) et même jusqu'au faciès schistes verts (400 °C) dans les ceintures dharwariennes de roches vertes.Un épisode tardif de métamorphisme de faciès amphibolites et schistes verts est limité aux zones à décollement intense d'âge protérozoïque. Dans la région méridionale il s'est produit un rétromorphisme des roches granulitiques dans la zone des charnockites et khondalites.Les conditions de pression et température ont été déduites de l'application de données sur la stabilité des minéraux et de méthodes de géothermométrie et de géobarométrie pour la région entre Shimoga-Chitradurga (nord) et Coimbatore-Karur (sud).
, . , , 3400 2500 . , , 2600 , , , . (700–750 °, 8–10 ). / - , 2. (600 °, 6–8 ) Dharwar (400 °). . / , . , Shimoga-Chitradurga () Coimbatore-Karur ().
The present study is part of a joint project of Benaras Hindu University at Varanasi and University of Kiel. Financial Support by the Deustche Forschungsgemeinschaft is gratefully acknowledged.
We especially thank M. N. Viswanatha, Geological Survey of India, for his cooperation during the field work. 相似文献
28.
Summary A study of the wavelength exponent of aerosol scattering in the Ångström relation for extinction by aerosol has been made from the ground-based measurments of direct solar radiation using Ångström pyrheliometer with and without Schott filters. It has been observed that in India, mainly for the middle part of the year this exponent is zero or even negative which means that the aerosol scattering is nearly neutral which is in marked contrast with the condition prevailing in middle latitudes. It is evident from the -values that the aerosol size distribution in India is far different from that prevailing in middle latitudes. At four representative stations in India, the values of the wavelength exponent and the atmospheric turbidity coefficient have been determined using the method introduced byÅngström [1,2]) and are discussed here. 相似文献
29.
Sandeep A. Joshi P. Kumari S. Lal Vandana Parveen Kumar Kamal 《Journal of the Geological Society of India》2017,89(6):719-722
High frequency ground motion simulation techniques are powerful tools for designing earthquake resistant structures in seismically active regimes. Simulation techniques also provide the synthetic strong ground motion in the regions where actual records are not available (Kumar et al. 2015).These techniques require several parameters of earthquake and other seismic information proceeding to the simulation. Practically estimation of parameters is a tough task, particularly in a region with limited information. This demands a simulation technique based on the easily estimated parameters for a new site. The purposes of this paper are to briefly review existing simulation techniques and to discuss in detail the new, simple and effective semi-empirical technique (Midorikawa 1993) of strong motion simulation. 相似文献
30.
The annealing characteristics of fission tracks in allanite have been studied. All the tracks in the mineral fade at 720° C for one hour heating. The activation energy of allanite ranges from 1.4 to 3.4 eV. 相似文献