全文获取类型
收费全文 | 112篇 |
免费 | 19篇 |
国内免费 | 25篇 |
学科分类
地球科学 | 156篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 10篇 |
2021年 | 5篇 |
2020年 | 8篇 |
2019年 | 5篇 |
2018年 | 12篇 |
2017年 | 8篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 6篇 |
2013年 | 11篇 |
2012年 | 10篇 |
2011年 | 14篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 8篇 |
2007年 | 1篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有156条查询结果,搜索用时 0 毫秒
41.
42.
43.
Studies on culture condition and extracellular hydrolase of psychrophilic bacteria from Arctic sea ice 下载免费PDF全文
Arctic sea ice in the polar region provides a cold habitat for microbial community.Arctic sea ice microorganisms are revealed to be of considerable impor- tance in basic research and potential in biotechnological application.This paper in- vestigated the culture condition and extracellular hydrolase of 14 strains of different Arctic sea ice bacteria.The results showed that optimal growth temperature of strains is 15℃or 20℃.The optimal pH is about 8.0.They hardly grow at acid condition. 3% NaCl is necessary for better growth.These strains have different abilities in pro- ducing amylase,protcase,cellulase and lipase.Pseudoalteronomas sp.Bsi429 and Pseudoalteronomas sp.Bsi539 produced both cellulose,protease and lipase.These results provide a basis for further developing and exploiting the cold adapted marine enzyme resources. 相似文献
44.
自记记录脏乱的原因及对策张琳(陇县气象局陇县·721200)在整理地面气象观测资料自记纸时发现,自记纸上自记墨水污迹较多;自记迹线粗细不均匀;观测自记读数的数值更改的较多;记录零乱。这些不良现象的存在严重影响了自记记录的美观整洁和自记记录读数的准确性... 相似文献
45.
本文介绍了对北京、天津、文安、霸县地区1980~1988年的重力复测成果所进行的地形变地下水的校正。分析认为:近几年天津点的重力值增大主要是因地面沉降造成的;经综合校正后,天津点的重力异常可基本排除,而任丘-保唐-沧州-带仍存在+80~100×10~(-8)m/s~2左右的趋势性异常。 相似文献
46.
Detection of 36 antibiotics in coastal waters using high performance liquid chromatography-tandem mass spectrometry 总被引:2,自引:0,他引:2
Among pharmaceuticals and personal care products released into the aquatic environment, antibiotics are of particular concern, because of their ubiquity and health effects. Although scientists have recently paid more attention to the threat of antibiotics to coastal ecosystems, researchers have often focused on relatively few antibiotics, because of the absence of suitable analytical methods. We have therefore developed a method for the rapid detection of 36 antibiotic residues in coastal waters, including tetracyclines (TCs), sulfanilamides (SAs), and quinolones (QLs). The method consists of solid-phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, using electrospray ionization (ESI) in positive mode. The SPE was performed with Oasis HLB and Oasis MCX cartridges. Chromatographic separation on a C18 column was achieved using a binary eluent containing methanol and water with 0.1% formic acid. Typical recoveries of the analytes ranged from 67.4% to 109.3% at a fortification level of 100 ng/L. The precision of the method, calculated as relative standard deviation (RSD), was below 14.6% for all the compounds. The limits of detection (LODs) varied from 0.45 pg to 7.97 pg. The method was applied to determine the target analytes in coastal waters of the Yellow Sea in Liaoning, China. Among the tested antibiotics, 31 were found in coastal waters, with their concentrations between the LOD and 212.5 ng/L. These data indicate that this method is valid for analysis of antibiotics in coastal waters. The study first reports such a large number of antibiotics along the Yellow Sea coast of Liaoning, and should facilitate future comprehensive evaluation of antibiotics in coastal ecosystems. 相似文献
47.
48.
从北大西洋中高纬度进入北极的极端气旋会引起北极异常增暖,与中高纬度极端天气事件关系密切,危害极大。利用ERA-Interim再分析资料和中国地面气象站观测资料,探讨了2015年1—2月两个极端气旋(C1,C2)影响中国天气的物理过程和机制。结果表明:当极端气旋生成并北移,附近大气低层和高层均出现异常增暖,中高纬度大气环流表现为乌拉尔阻塞形势形成,极涡断裂,低压槽加深南压,我国发生寒潮天气;且极端气旋伴随的异常增暖加强Rossby波能量频散,使中高纬度的槽和脊发展。对比发现,C1和C2的生成地和路径均存在差异,相比于C2,C1生成纬度较高且路径偏东,对应低温寒潮天气范围更大,但强度比C2略弱。这些结果均表明,极端气旋的生成和移动是中国寒潮天气发生的重要原因之一。 相似文献
49.
中冶京诚工程技术有限公司亦庄第二办公区的建筑设计着意于实现建筑对员工的服务功能,体现以人为本的企业精神,强调建筑与周边景观的有机融合。在空间布局、建筑体型、节约能耗等方面突出项目的社会性、经济性以及建绿色环境的特点。 相似文献
50.
Axenic microalgal strains are highly valued in diverse microalgal studies and applications. Antibiotics, alone or in combination, are often used to avoid bacterial contamination during microalgal isolation and culture. In our preliminary trials, we found that many microalgae ceased growing in antibiotics at extremely high concentrations but could resume growth quickly when returned to an antibiotics-free liquid medium and formed colonies when spread on a solid medium. We developed a simple and highly efficient method of obtaining axenic microalgal cultures based on this observation. First, microalgal strains of different species or strains were treated with a mixture of ampicillin, gentamycin sulfate, kanamycin, neomycin and streptomycin (each at a concentration of 600 mg/L) for 3 days; they were then transferred to antibiotics-free medium for 5 days; and finally they were spread on solid f/2 media to allow algal colonies to form. With this method, five strains of Nannochloropsis sp. (Eustigmatophyceae), two strains of Cylindrotheca sp. (Bacillariophyceae), two strains of Tetraselmis sp. (Chlorodendrophyceae) and one strain of Amphikrikos sp. (Trebouxiophyceae) were purified successfully. The method shows promise for batch-purifying microalgal cultures. 相似文献