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241.
Rolf Sander 《Surveys in Geophysics》1999,20(1):1-31
For detailed modeling of atmospheric chemistry it is necessary to consider aqueous-phase reactions in cloud droplets and deliquesced aerosol particles. Often, the gas-phase concentration is in equilibrium with the aqueous phase. Then Henrys law can be used to describe the distribution between the phases provided that the Henrys law coefficient is known. In some cases, thermodynamic equilibrium will not be reached and it is necessary to use kinetic expressions of the rates involved. These rates depend on diffusion constants, accommodation coefficients, Henrys law coefficients, particle size distributions, and several other parameters. This review describes how these processes can be treated in computer modeling and how the necessary data can be obtained. Even though it is written primarily for use in modeling atmospheric chemistry, some parts will also be useful for waste water and pesticide control and in other areas where the distribution of chemicals between the aqueous and the gas phase is important. 相似文献
242.
气溶胶与全球热辐射平衡、水循环、人类健康密不可分,其观测精度直接影响天气预测、气候建模以及对人类健康影响评估的精度,激光雷达能监测气溶胶的垂直分布,对污染气溶胶的扩散趋势、污染源反演、气候预测等均有重要意义。本文基于激光在大气中的辐射传输过程,根据米散射激光雷达的工作原理,使用雷达的多个系统参数计算雷达常数,建立激光雷达气溶胶质量浓度反演模型,从地面向上在晴空条件下进行了珠三角地区典型区域的秋冬季节气溶胶垂直观测的实验,计算气溶胶质量浓度的垂直廓线,反演气溶胶的垂直分布情况。验证与分析结果表明:(1)激光雷达反演结果显示,白天的反演结果中噪声大大减少,表明反演算法能够有效减弱太阳光的影响。(2)相比于传统方法,使用雷达常数而非边界值的反演结果波动较小,更符合实际,能够有效避免高空噪声的影响。(3)高层大气在晴朗静稳天气状况下较为干净,气溶胶基本分布在低空区域,质量浓度随高度基本呈负指数分布。 相似文献
243.
244.
PRELIMINARY STUDY OF VARIATION OF SO_2 AND AEROSOL PARTICLE BACKGROUND CONCENTRATIONS IN THE EASTERN CHINA
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The average concentrations of sulphur dioxide,sulfate aerosol and TSP were about 8—10 ppb,15.08 μg m~(-3),and241.40 μg m~(-3) respectively,which were measured at the Lin'an regional background station during August—November,1991.The higher concentrations of SO_2 and SO_4~(2-) maybe acidify the rainfall.It has a great influence uponthe human health and ecosystem.The simulated results indicate that the distributions of SO_2 and SO_4~(2-) were deter-mined by local emission sources.Average aerosol particle number density was 2.0×10~4 cm~(-3).It shows that social devel-opment and human activities strongly affect the atmospheric background level. 相似文献
245.
A. Hallberg K. J. Noone J. A. Ogren I. B. Svenningsson A. Flossmann A. Wiedensohler H. -C. Hansson J. Heintzenberg T. L. Anderson B. G. Arends R. Maser 《Journal of Atmospheric Chemistry》1994,19(1-2):107-127
The partitioning of aerosol particles between cloud droplets and interstitial air by number and volume was determined both in terms of an integral value and as a function of size for clouds on Mt. Kleiner Feldberg (825 m asl), in the Taunus Mountains north-west of Frankfurt am Main, Germany. Differences in the integral values and the size dependent partitioning between two periods during the campaign were observed. Higher number and volume concentrations of aerosol particles in the accumulation mode were observed during Period II compared to Period I. In Period I on average 87±11% (±one standard deviation) and 73±7% of the accumulation mode volume and number were incorporated into cloud droplets. For Period II the corresponding fractions were 42±6% and 12±2% in one cloud event and 64±4% and 18±2% in another cloud event. The size dependent partitioning as a function of time was studied in Period II and found to have little variation. The major processes influencing the partitioning were found to be nucleation scavenging and entrainment. 相似文献
246.
247.
S. Ghosh 《Journal of Earth System Science》1993,102(1):265-270
Uptake of trace gases by (stratospheric aerosol can be significant particularly after large injections of volcanic sulphur.
A theoretical scheme is presented to quantify the rate at which trace gases diffuse into these aerosol droplets. Rate constants
for 19 trace gases are calculated and it is found that the rates vary from a value of 2.85 × 10-7s-1 for CC14 to 8.08 × 10-7s-1 for NO. The calculations are characterised by their ease of application and can be incorporated into stratospheric chemical
models. 相似文献
248.
Josef Podzimek 《Pure and Applied Geophysics》1983,121(4):611-632
In the light of new measurements of small aerosol particles in the lower stratosphere, some of the old investigations—which
were only published in part in scientific journals—are reviewed and compared. The discussion focuses on whether the Aitken
nuclei (AN) size distribution up to 20 km can be described by Junge’s or log-normal density functions and under what circumstances
one can find a bimodal distribution of these particles. The ion flow in correlated to the stratospheric pollution (intercept
with the jet aircraft, volcanic activity) and is, in mean, directly proportional to the aircraft altitude in the undisturbed
lower stratosphere.
Note: The GCCPR, Univ. Missouri at Rolla, reports quoted in the article can be obtained from the author. 相似文献
249.
T. A. Mather A. G. Allen C. Oppenheimer D. M. Pyle A. J. S. McGonigle 《Journal of Atmospheric Chemistry》2003,46(3):207-237
We present the first application of a multi-stage impactor to study volcanic particle emissions to the troposphere from Masaya volcano, Nicaragua. Concentrations of soluble SO4
2–,Cl–, F–, NO3
–, K+, Na+,NH4
+, Ca2+ and Mg2+ were determined in 11 size bins from 0.07 m to >25.5 m. The near-source size distributions showed major modes at 0.5m (SO4
2–, H+,NH4
+); 0.2 m and 5.0 m (Cl–) and 2.0–5.0 m(F–). K+ and Na+ mirrored the SO4
2– size-resolvedconcentrations closely, suggesting that these were transported primarily asK2SO4 and Na2SO4 in acidic solution, while Mg2+ andCa2+ presented modes in both <1 m and >1 m particles. Changes in relative humidity were studied by comparing daytime (transparent plume) and night-time (condensed plume) results. Enhanced particle growth rates were observed in the night-time plume as well as preferential scavenging of soluble gases, such as HCl, by condensed water. Neutralisation of the acidic aerosol by background ammonia was observed at the crater rim and to a greater extent approximately 15 km downwind of the active crater. We report measurements of re-suspended near-source volcanic dust, which may form a component of the plume downwind. Elevated levels ofSO4
2–, Cl–, F–,H+, Na+, K+ and Mg2+ were observed around the 10 m particle diameter in this dust. The volcanic SO4
2– flux leaving the craterwas 0.07 kg s–1. 相似文献
250.
XLS-Ⅱ型系留气艇探测系统 总被引:6,自引:0,他引:6
简单描述了系留气艇运动的基本力学原理,较详细地介绍了国产XLS-Ⅱ型系留气艇探测系统的基本组成、结构和主要技术指标。系统的绞车重36kg,电机功率600W,拉线最大拉力为175kg。与系统配套的有气象要素、大气臭氧和大气气溶胶等探测单元。给出了主要气象和某些环境要素的探测精度和应用实例并简单讨论了系留气艇探测系统在实际应用的某些问题。 相似文献