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991.
992.
H. Yu W. Huang Y. H. Duan J. C. L. Chan P. Y. Chen R. L. Yu 《Meteorology and Atmospheric Physics》2007,97(1-4):189-206
Summary A new typhoon model named as GRAPES_TCM is applied to study the pre-landfall erratic track of Typhoon Haitang (2005), which
hit China twice in mid-July by making landfall in Taiwan and Fujian provinces consecutively. The model is based on the Chinese
Global/Regional Assimilation and PrEdiction System (GRAPES) and put into real-time operational test since 2004. It predicts
almost correctly the pre-landfall loop and sharp turn of Haitang and its asymmetric rainfall distribution.
Haitang’s erratic track is well explained by the potential vorticity (PV) theory on tropical cyclone motion, with the typhoon
center moving toward the area of maximum wave-number 1 (WN1) PV tendency most of the time. Among the terms contributing to
the WN1 PV tendency, the horizontal advection of PV is dominant with the diabatic heating and residual terms also being not
negligible.
A sensitivity experiment is carried out with removal of the Taiwan terrain to determine its importance in the erratic track
of Haitang and it is found that the basic erratic feature of Haitang’s track remians unchanged although it tends to have a
larger loop and a weaker northward turn, which suggests that Taiwan terrain may not be a key factor here.
The sudden change of Haitang’s moving direction is always accompanied by a newly-generated or re-intensified WN1 PV center
in the southern semicircle, which circles around the TC center cyclonically afterwards and weakens in the north or northwestern
part. A phase-lock WN1 PV forcing related to diabatic heating is proposed to be the major contributor, the importance of which
is magnified as it is in phase with the WN1 horizontal advection of PV. The intrusion of mid-level warm and dry air, as well
as the existence of a low-level southwesterly jet, is considered to be the main reasons for such a phase-lock of the diabatic
heating forcing on the PV tendency field that finally results in the erratic track of Haitang. 相似文献
993.
低纬高原地区MM5v3不同参数化方案降水模拟试验 总被引:1,自引:2,他引:1
为了进一步了解MM5模式在低纬高原降水预报性能,利用MM5模式中的3个物理过程组合了7个不同的参数化试验方案,对低纬高原地区2005年主汛期进行了降水数值试验。结果表明:第三重嵌套网格中的Grell积云参数化、Goddard显式水汽和Cloud(或RRTM)辐射过程组合的试验方案对降水预报效果较好,特别是对大雨和暴雨预报有明显的改善;在将试验结果插值到测站点时,不同扫描半径对插值结果有一定影响,相对而言,20~30km扫描半径插值结果较为理想。 相似文献
994.
为了研究全球大气位势高度场的气候变率, 利用NCEP/NCAR再分析资料, 按照距平高度场平均强度指数 (Ia) 分析发现, 半球距平高度场强度呈年单周振荡, 冬大夏小, 冬季随高度单调增大, 夏季有弱高、低值中心出现, 而北、南半球的差异明显表现在季节变化上; 进一步根据半球大气位势高度距平场球函数谱低维、低阶的基本特征, 将半球环流异常分为半球均匀异常 ( H ′00)、纬向均匀异常 ( H ′0)、超长波尺度异常 ( H ′ul) 和长波尺度异常 ( H ′l) 4种类型, 用波数域0≤m, k≤6上的球函数系数资料求得它们的方差贡献, 给出了4类异常的方差贡献随高度、季节变化的规律以及它们的半球际差异。由此得到异常环流球函数谱结构的总体特征为:对流、平流层之间存在明显变化。从对流层进入平流层, 一般由超长波异常为主转为纬向均匀异常为主 (冬半球) 或半球均匀为主 (夏半球); 半球均匀异常在对流层中不重要, 长波尺度异常在平流层中不重要, 它们拟合异常方差一般均小于10%; 北、南半球最大差异表现在冬季平流层R′00和冬、夏季对流层R′0南半球大于北半球, 冬、夏季对流层R′l北半球大于南半球。 相似文献
995.
Laminaria gametophyte was greatly influenced by light in its growth and development. Using light-emitting diodes (LED) as blue and
red light sources, we analyzed the light effect on gametophytes development ofLaminaria japonica Aresch. The gametophytes were obtained from zoospores collected in April, May, July, 2003 and September, 2004. We found that
the growth of gametophytes was stimulated by increasing intensity of blue light (BL) and red light (RL) illumination, of which
BL was obviously stronger than that of RL. The fertilization of gametophytes depended largely on BL, and only sufficient BL
illumination could take the reproductive effect. In addition, we noticed that there was a significant difference in light
responses for gametophytes developed from zoospore collected in different times. For zoospores released in April, under BL1 (73.90 μmol photons/m·s), the unicellular female gametophytes and multi-cellular male gametophytes produced eggs and sperms
respectively, and further developed towards sporophytes. However, for gametophytes developed in May, July or September, they
became multi-cellular and never formed oogonia or antheridia. It is believed that theLaminaria sporangium maturation stage could affect the gametophytes reaction to BL under laboratory culture conditions. Therefore,
cryptochrome- or phototropin-like BL photoreceptors is probably involved in BL-induced development ofLaminaria gametophytes.
This research was supported by the NSFC (No.40376049) and Japan Society for the Promotion of Science (The Invitation Fellowship
for Research in Japan 2002). 相似文献
996.
Observation of female gamete (Carpogonia) germination of Porphyra yezoensis and P. oligospermatangia
Several papers have reported that part or whole leafy thallus seemingly consisting of zygotospores can give rise to both blades
and conchocelis in the same culture ofPorphyra. Study on samples of wild and cultivatedPorphyra yezoensis andP. oligospermatangia were conducted to clarify the origination of the young blades in the culture. It is confirmed that single cells on the blade
of both species, which normally intermixed with zygotospores, germinated into young blades. TEM and SEM observation has shown
that the single cells ofPorphyra yezoensis had typical features of female gamete (carpogonia) but archeospore. Therefore, the female gametes are responsible in developing
leafy thalli.
This project was sponsored by the NSFC (No. C-0205-05-39770593) 相似文献
997.
998.
利用适合性检验方法,对云南省125个测站1961年一2000年40a逐月降水资料是否符合正态分布进行了检验,并对云南降水正态分布做了区划。研究结果表明,云南在雨季(5—10月)通过显著性检验的测站数明显少于干季(11一次年4月)通过显著性检验的测站数,其中8月份仅4站次通过显著性检验,而12月份高达97站次,占全省总站次的77.6%;即云南雨季降水多符合正态分布,而在于季多符合非正态分布,8月份几乎全省符合正态分布,而12月份大部份测站都不符合正态分布。云南降水量的正态统计分布一方面具有一定的区域性特征,另一方面又具有较强的局地性,不同的月份同一测站降水量的正态性不同。因此,在做有关降水量的分析预报时,很有必要考虑其正态性的统计分布特征。 相似文献
999.
Dinghua Huang Yichun Duan Bin Li Lingqing Yao Heng Zhang Fan Zhang Junhui Wang Hao Guo Hongfu Yin 《中国科学D辑(英文版)》2002,45(8):730-740
On the centimeter scale of lithologic change, we conduct poly-statistic analysis on the sedimentary behavior and dynamic features
of the stratigraphic sequence from upper Dalong formation to lower Daye formation, which across the Permian-Triassic boundary
in East Hubei. From the perspective of stochastically dynamic system, the depositional process of upper Dalong formation can
be regarded as a stable Markovian process with weakly stratigraphie correlation and randomly lithologic alteration. Compared
to it, the depositional process of lower Daye formation was unstable Markovian process with much closer stratigraphic correlation
and ordered lithologic change. As for the replacement style of the sedimental cycle, the former was chaotic, while the latter
was periodical. Otherwise, although the overall depositional process of the two formations was continuous, their dynamic characteristics
were obviously different. So this P-T sedimental boundary can also be regarded as a dynamic limit. It was a kind of depositional
reaction in response to a catastrophic alteration when the geological environment was in continuous change but came over a
certain threshold state. 相似文献
1000.
1 Geologic setting and layout of the DSS observation network In the studied area there are three major tectonic units, which are referred to as Tianshan fold system, Tarim basin and West Kunlun fold system (Bureau of Geology and Mineral Resources of Xinjiang Uygur Autonomous Region, 1993). The Tianshan fold system is a polycyclic geosyncline on the north edge of Tarim basin, and an orogenic zone resulting from collision and convergence between Tarim block and the Junggar-North Tianshan… 相似文献