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991.
飞机积冰是影响飞行安全的重要危险天气,准确的积冰诊断对民航运行与安全具有重大意义,特别是对国产大飞机适航取证具有重要作用。本文参考改进的CIP(Current Icing Potential)指数,使用垂直速度和云中液态水含量对积冰潜势诊断指数进行优化得到SCIP(Simplified Current Icing Potential)指数,该指数直接基于大气层结资料给出较为准确地飞机积冰潜势,具有命中率高、实用性强的特点。用2021年2月28日至12月31日民航航空器报告对原CIP指数和SCIP指数进行对比验证评估,发现相比于原CIP指数,SCIP指数具有更优异的ROC曲线(Receiver Operating Characteristic Curve)和TSS评分(True Skill Score)。但是对于不同程度的积冰,原CIP指数和SCIP指数均表现出较一致诊断效果,表明SCIP指数对诊断飞机积冰潜势具有重要作用,但无法判断积冰强度。根据2020年3月16日陕西区域飞机结冰个例验证表明增加垂直速度和云中液态水含量的影响对飞机积冰的描述更加细致,对提升积冰潜势诊断效果具有重要意义... 相似文献
992.
Formation and early development of tetraspores of Polysiphonia urceolata (Rhodomelaceae, Rhodophyta)
Polysiphonia urceolata is one type of potential commercial red seaweeds used for breeding and cultivation, because of its significant biochemical
and biomedical application. However, the information of breeding and seedling incubation for cultivation is limited, especially
the early development. In this study, tetrasporohyte and gametophyte of P. urceolata were taken as the study materials in Huiquan Bay, Qingdao, China. The cleaned and sterilized tetrasporophytes and gametophytes
were pre-cultured in sterilized seawater, then nurtured at 18°C, 25 μmol photons m−2 s−1 in 12:12 h (light:dark) photoperiod. Continuous observation under microscope showed that the early development consists of
bipolar division stage and seedling stage. In the division stage, tetraspores germinate into bipolar sporelings that further
differentiate into a colorless rhizoidal portion and a lightly pigmented upright shoot. The lightly pigmented rhizoidal cell
develops to a rhizoid and the larger pigmented cell transforms to an erect axis. In the seedling stage, several quasi-protuberances
appear on the erect axis and form juvenile seedlings. The results demonstrate the culture of P. urceolata from tetraspores under laboratory conditions.
Supported by National Key Technology Support Program, Development Program of China (No.2006AA09Z21), National Natural Science
Foundation of China (No. 40618001 and N_CUHK438/06) and Shandong Agricultural Seed Stock Breeding Project 相似文献
993.
994.
V. G. Bondur Yu. V. Grebenyuk K. D. Sabynin 《Izvestiya Atmospheric and Oceanic Physics》2009,45(5):598-607
Based on the results of analyzing the characteristics of currents and temperature measured in the water space of the Mamala
Bay (the Island of Oahu, Hawaii), we investigate the main properties of the field of short-period internal waves, which is
very complex. We focus on analyzing the spectral characteristics and orbit parameters for waves with a period of 20 minutes.
The results of investigations reveal two types of short-period internal waves for this area: intense and fast waves propagating
predominantly toward the ocean and weaker and slower waves propagating mainly toward the coast. Suppositions are made on how
these waves form: the strong and fast waves are likely to be caused by the decay of locally generated internal tides near
the shelf edge, while the weak and slow and very short waves seem to result from the specific interaction between the pycnocline
and strong tidal currents over a steep slope. 相似文献
995.
An integral description of the propagation of steady-state perturbations of the heavy liquid surface
The system of equations of motion describing the gravity wave propagation in a perfect heavy liquid layer is transformed into
a new integral equation for the free surface elevations. In the limit cases, this integral equation describes the linear and
nonlinear periodic waves as well as the known types of solitary waves. In this case a dispersion equation arises because perturbations
of the second and higher orders of smallness are neglected. The integral equation allows for the propagation of invariable
surface perturbations of arbitrary forms if their spatial spectrum is concentrated near small wave numbers (compared to the
inverse wave amplitude). Several examples of solutions are presented. 相似文献
996.
Yu. A. Fedorov I. V. Dotsenko A. N. Kuznetsov A. A. Belov E. A. Loginov 《Oceanology》2009,49(2):211-217
The principal regularities were ascertained for the spatiotemporal distribution of organic carbon in the water and bottom sediments of the Russian part of the Sea of Azov. The relationships between allo- and autochthonous organic matter in water and bottom sediments from different parts of the sea aquatic area were found. The behavior of organic carbon in the water-bottom sediments system was characterized as the effect of the variability of hydrochemical, biological, and hydrological factors ad processes. 相似文献
997.
Nannochloropsis oculata CS179, a unicellular marine microalga, is rich in long-chain polyunsaturated fatty acids (LCPUFAs). Elongase and desaturase
play a key role in the biosynthesis of PUFAs. A new elongase gene, which encodes 322 amino acids, was identified via RT-PCR and 5′ and 3′ RACE. The sequence of the elongase gene was blast-searched in the NCBI GenBank and showed a similarity
to those of the cryptosporidium. But the NJ-tree revealed that the N. oculata CS179 elongase clustered with those of the microalgae Phaeodactylum tricornutum, Ostreococcus tauri and Thalassiosira pseudonana. 相似文献
998.
999.
Seiche oscillations of the Azov Sea level are studied on the basis of the developed two-dimensional numerical hydrodynamic
model grounded on the shallow water theory and recent data on the morphometric characteristics of the Sea of Azov. Frequency
and spatial characteristics of the first five modes corresponding to seiche oscillations of the Azov Sea level are computed.
It is shown that the frequency and spatial characteristics of the first five modes obtained for the Sea of Azov level changes
correspond to seiche oscillations. The calculated parameters are compared with the field observations, which show their realistic
character. 相似文献
1000.
In this work, the history of the development of the Turali area (the Dagestan coast of the Caspian Sea) in the Late Holocene
is under consideration. The analysis of the geological structure of the bay bar that separates the Bolshoy Turali lagoon from
the sea, the granulometric analysis of the coastal deposits, and the data of geo-radar profiles make it possible to assert
that the large eolian relief forms were formed during the New Caspian (Novokaspiyskoe) transgression of the Caspian Sea. 相似文献