全文获取类型
收费全文 | 207篇 |
免费 | 31篇 |
国内免费 | 14篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 31篇 |
地球物理 | 81篇 |
地质学 | 94篇 |
海洋学 | 10篇 |
天文学 | 13篇 |
综合类 | 1篇 |
自然地理 | 21篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 11篇 |
2021年 | 13篇 |
2020年 | 9篇 |
2019年 | 5篇 |
2018年 | 18篇 |
2017年 | 11篇 |
2016年 | 10篇 |
2015年 | 12篇 |
2014年 | 13篇 |
2013年 | 18篇 |
2012年 | 12篇 |
2011年 | 19篇 |
2010年 | 19篇 |
2009年 | 15篇 |
2008年 | 9篇 |
2007年 | 6篇 |
2006年 | 7篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1993年 | 4篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1979年 | 3篇 |
1975年 | 1篇 |
排序方式: 共有252条查询结果,搜索用时 46 毫秒
101.
为揭示青藏高原湿地浮游植物功能群时空分布特征与环境因子的关系,本文于2019年7月(丰水期)和2019年10月(枯水期)在麦地卡湿地调查浮游植物功能群组成和生物量,并运用Spearman相关性分析、冗余分析(RDA)和典范对应分析(CCA)等方法,对麦地卡湿地浮游植物功能群时空分布特征及其与环境因子的关系进行分析.结果表明:1)根据功能群分类方法,麦地卡湿地浮游植物可划分为27个功能群,分别为A、B、C、D、E、F、G、H1、J、K、LM、LO、M、MP、N、P、S1、S2、T、TB、TC、W1、W2、X1、X2、X3和Z;在时间维度上,丰水期有26个功能群,枯水期有23个功能群;在空间维度上,河流湿地有24个功能群,湖泊湿地有23个功能群,沼泽湿地有12个功能群.2)丰水期,以功能群A、D、LM、LO、MP、N、P、T、TB和X3为主,枯水期以功能群A、D、J、LM、LO、MP、N、P、T和TB为主,其中A和T功能群为2个水情期的共有绝对优势功能群,功能群J仅为枯水期的绝对优势功能群.3)生态状态指数(Q)范围为1.80~4.86,平均值为3.80,表明麦地卡湿地水质状态为“好”.4)相关性分析表明,浊度、CODCr、总磷和硝态氮与部分优势功能群生物量具有显著相关性;RDA分析表明,盐度和总氮是影响丰水期优势功能群生物量的主要环境因子.CCA分析表明,总氮和硝态氮是影响枯水期优势功能群生物量的主要环境因子. 相似文献
102.
Michal Baťka 《Studia Geophysica et Geodaetica》1991,35(2):109-124
Summary The CHMI LAOFM is used in the daily routine of the Central Forecasting Office of the Czech Hydrometeorological Institute and some special results are transmitted to the regional offices. The model works in the region of Europe and the North Atlantic, uses conservative finite difference schemes and two types of semi-implicit schemes that allow effective model structurization in terms of programming language. The basic philosophy of the model is described.
¶rt; a zau mumuu unm zumzu umumm () ¶rt; z uz nza. m mam ¶rt;a zu nzam am amuu. z amam amu n u amu mamuz aa, un am , a a aa au. ama aum mu auau z n- , ma cam m nm a auuam mmauau nza. mam nuaa u u auauu.相似文献
103.
In the standard method of electron density determination for soft X-ray (SXR) flare kernels, it is necessary to assume what
the extent is of a kernel along the line of sight. This is a source of significant uncertainty of the obtained densities. 相似文献
104.
Asymptotic solution for the two-body problem with constant tangential thrust acceleration 总被引:1,自引:0,他引:1
Claudio Bombardelli Giulio Baù Jesus Peláez 《Celestial Mechanics and Dynamical Astronomy》2011,110(3):239-256
An analytical solution of the two body problem perturbed by a constant tangential acceleration is derived with the aid of
perturbation theory. The solution, which is valid for circular and elliptic orbits with generic eccentricity, describes the
instantaneous time variation of all orbital elements. A comparison with high-accuracy numerical results shows that the analytical
method can be effectively applied to multiple-revolution low-thrust orbit transfer around planets and in interplanetary space
with negligible error. 相似文献
105.
Demonstrated is an influence of synoptic processes on the seasonal dynamics of the Vietnamese Current in the South China Sea varying its direction under the influence of the monsoon. The spring season of 1999 is used as an example of the transition from the winter to summer. In winter, under the influence of the northeastern monsoon, the current is directed from north to south and in the summer, at the southwestern monsoon, in the opposite direction. In the spring, two zones of different water modification are formed: an impact is observed of both the leaving winter monsoon and the coming summer monsoon. Considered is an atmospheric process of low-gradient field type, when the pressure field is characterized by the low pressure gradient over the whole South China Sea. It is revealed that the Vietnamese Current moves in the summer regime (from south to north) in the northern and southern parts and keeps the winter regime (from north to south) in the central part. 相似文献
106.
107.
108.
The use of kaolinite‐based clay minerals as a low‐cost natural adsorbent for the removal of Cu(II) from electroplating waste leachate was studied. Batch experiments were conducted to determine the effects of varying adsorbent loading, initial pH, adsorbent dosage, and contact time. Box–Behnken design with three variables like initial pH, adsorbent dosage, and contact time at three different levels was studied to identify a significant correlation between the effects of these variables to the amount of Cu(II) adsorbed. The methodology identifies the principal experimental variables, which have the greatest effect on the adsorption process. After optimizing the input variables by using Simplex algorithm, the adsorption of Cu(II) was maximal (99.9% with a maximum (positive) standard deviation of 9.4) at pH 6.24, adsorbent dosage of 0.83 g L?1, and contact time of 97 min, respectively. Furthermore, the experimental values are in good agreement with predicted values, the correlation coefficient and adjusted correlation coefficients were found to be 0.96 and 0.87, respectively. 相似文献
109.
F. Ekmekçi A. Elmaslı M. Yılmaz T. Kılıçoğlu T. Tanrıverdi Ö. Baştürk H.V. Şenavcı Ş. Çalışkan B. Albayrak S.O. Selam 《New Astronomy》2012,17(7):603-609
With the aim of providing new and up-to-date absolute parameters of some close binary systems, new BVR CCD photometry was carried out at the Ankara University Observatory (AUG) for five eclipsing binaries, ET Boo, V1123 Tau, V1191 Cyg, V1073 Cyg and V357 Peg between April, 2007 and October, 2008. In this paper, we present the orbital solutions for these systems obtained by simultaneous light and radial velocity curve analyses. Extensive orbital solution and absolute parameters for ET Boo system were given for the first time through this study. According to the analyses, ET Boo is a detached binary while the parameters of four remaining systems are consistent with the nature of contact binaries. The evolutionary status of the components of these systems are also discussed by referring to their absolute parameters found in this study. 相似文献
110.
Natural Resources Research - We thank Zhang et al. (Nat Resour Res, 2019. https://doi.org/10.1007/s11053-019-09512-6) for investigating the accuracy of artificial intelligence techniques in the... 相似文献