全文获取类型
| 收费全文 | 147篇 |
| 免费 | 35篇 |
| 国内免费 | 24篇 |
专业分类
| 测绘学 | 31篇 |
| 大气科学 | 21篇 |
| 地球物理 | 17篇 |
| 地质学 | 58篇 |
| 海洋学 | 47篇 |
| 天文学 | 9篇 |
| 综合类 | 15篇 |
| 自然地理 | 8篇 |
出版年
| 2023年 | 3篇 |
| 2022年 | 5篇 |
| 2021年 | 5篇 |
| 2020年 | 4篇 |
| 2019年 | 11篇 |
| 2018年 | 9篇 |
| 2017年 | 5篇 |
| 2016年 | 6篇 |
| 2015年 | 8篇 |
| 2014年 | 11篇 |
| 2013年 | 22篇 |
| 2012年 | 13篇 |
| 2011年 | 12篇 |
| 2010年 | 11篇 |
| 2009年 | 10篇 |
| 2008年 | 5篇 |
| 2007年 | 9篇 |
| 2006年 | 9篇 |
| 2005年 | 8篇 |
| 2004年 | 3篇 |
| 2003年 | 2篇 |
| 2002年 | 4篇 |
| 2001年 | 5篇 |
| 2000年 | 3篇 |
| 1999年 | 6篇 |
| 1998年 | 3篇 |
| 1997年 | 2篇 |
| 1996年 | 1篇 |
| 1994年 | 5篇 |
| 1993年 | 1篇 |
| 1992年 | 1篇 |
| 1991年 | 1篇 |
| 1990年 | 2篇 |
| 1989年 | 1篇 |
排序方式： 共有206条查询结果，搜索用时 156 毫秒
11.
12.
13.
TS50全站仪配合徕卡多测回测角软件能够自动瞄准、自动观测,具有高智能、高精度的特点,从而在地铁基坑监测领域得到广泛的应用。文章结合济南市轨道交通R1线前大彦站基坑监测项目实践,对测量方法、数据处理、监测效果等方面进行论述。实际应用表明:基于TS50全站仪的多测回测角软件能提供及时可靠的监测数据,科学指导基坑施工,保证了基坑安全,取得良好的效果。 相似文献
14.
Zn2+对日本沼虾(Macrobrachium nipponensis)的急性致毒效应 总被引：1，自引：0，他引：1
在水温(27.4±1.3)℃条件下,以体长(33.23±1.66)mm、体质量(0.7893±0.1518)g的日本沼虾为实验动物,采用静水停食法开展了Zn2+对日本沼虾的急性毒性实验,并以此为基础,测定了Zn2+不同质量浓度水平下日本沼虾的耗氧率与窒息点.结果表明:(1)Zn2+对日本沼虾的急性致死效应与其呼吸生理代谢受阻密切相关;(2) Zn2+对日本沼虾24h、48h、72h、96h的半致死质量浓度依次为1.493、0.844、0.643和0.464mg/L; (3) Zn2+对日本沼虾昼均、夜均和日均耗氧率均无显著影响的阈值为0.046mg/L,该值为Zn2+对日本沼虾急性毒性的安全质量浓度;(4) Zn2+对日本沼虾产生轻度胁迫和中度胁迫的质量浓度范围分别为0.046-0.064mg/L和0.064-0.082mg/L. 相似文献
15.
16.
Acute toxicities of potassium permanganate, formalin, and Lugol’s iodine solution to a commonly occurred marine ciliate Pleuronema coronatum (Ciliophora, Scuticociliatida) were measured. Linear regression analysis of the results highlighted the close relationships
between doses of the medicines and mortalities of the organisms, thus providing a capability to predict toxicity effects from
the dose. Toxic effects of the medicines on the ciliates were described in the present paper, and the median lethal concentrations
(LC50 values) were given. Results of measurements indicated that 2 h-LC50 and 12 h-LC50 values of formalin on P. coronatum were 59.00×10−6 and 43.57×10−6, while those of Lugol’s solutions were 90.13 and 67.84×10−6 respectively. The tolerance of P. coronatum to formalin is apparently lower than that to Lugol’s iodine solution and potassium permanganate is a suitable medicine to
kill ciliates in short time. 相似文献
17.
18.
19.
20.
《Astroparticle Physics》2009,32(2):112-119
SS433, located at the center of the supernova remnant W50, is a close proximity binary system consisting of a compact star and a normal star. Jets of material are directed outwards from the vicinity of the compact star symmetrically to the east and west. Non-thermal hard X-ray emission is detected from lobes lying on both sides. Shock accelerated electrons are expected to generate VHE gamma rays through the inverse-Compton process in the lobes. Observations of the western X-ray lobe region of SS433/W50 system have been performed to detect VHE gamma rays using the 10 m CANGAROO-II telescope in August and September, 2001, and July and September, 2002. The total observation times are 85.2 h for ON source, and 80.8 h for OFF source data. No significant excess of VHE gamma rays has been found at three regions of the western X-ray lobe of SS433/W50 system. We have derived 99% confidence level upper limits to the fluxes of gamma rays and have set constraints on the strengths of the magnetic fields assuming the synchrotron/inverse-Compton model for the wide energy range of photon spectrum from radio to TeV. The derived lower limits are G for the center of the brightest X-ray emission region and G for the far end from SS433 in the western X-ray lobe. In addition, we suggest that the spot-like X-ray emission may provide a major contribution to the hardest X-ray spectrum in the lobe. 相似文献