首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   68篇
  免费   0篇
丛书文集   2篇
教育与普及   1篇
现状及发展   19篇
研究方法   10篇
综合类   35篇
自然研究   1篇
  2021年   1篇
  2018年   1篇
  2016年   2篇
  2014年   2篇
  2012年   1篇
  2011年   3篇
  2009年   2篇
  2008年   5篇
  2007年   7篇
  2006年   7篇
  2005年   3篇
  2004年   3篇
  2003年   2篇
  2002年   1篇
  2001年   2篇
  2000年   5篇
  1999年   1篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1977年   3篇
  1974年   1篇
  1973年   3篇
  1970年   1篇
  1968年   3篇
  1967年   3篇
  1965年   1篇
  1960年   1篇
  1958年   1篇
排序方式: 共有68条查询结果,搜索用时 78 毫秒
1.
催化动力学测定痕量钴研究综述   总被引:1,自引:0,他引:1  
综述了近年来催化动力学光度法测定痕量钴的进展情况。对催化显色动力学光度法、催化褪色动力学光度法、催化荧光光度法、阻抑动力学光度法、催化化学发光光度法等几个类别,从反应介质、灵敏度、线性范围等方面介绍了对不同反应体系的研究情况,并对催化动力学光度法测定痕量钴的发展趋势做出预测。  相似文献   
2.
介绍了路基施工高边坡开挖安全措施,包括健全安全管理组织机构、施工安全措施、高空作业安全措施、机械作业安全措施等。  相似文献   
3.
Two-pore channel proteins (TPC) encode intracellular ion channels in both animals and plants. In mammalian cells, the two isoforms (TPC1 and TPC2) localize to the endo-lysosomal compartment, whereas the plant TPC1 protein is targeted to the membrane surrounding the large lytic vacuole. Although it is well established that plant TPC1 channels activate in a voltage- and calcium-dependent manner in vitro, there is still debate on their activation under physiological conditions. Likewise, the mode of animal TPC activation is heavily disputed between two camps favoring as activator either nicotinic acid adenine dinucleotide phosphate (NAADP) or the phosphoinositide PI(3,5)P2. Here, we investigated TPC current responses to either of these second messengers by whole-vacuole patch-clamp experiments on isolated vacuoles of Arabidopsis thaliana. After expression in mesophyll protoplasts from Arabidopsis tpc1 knock-out plants, we detected the Arabidopsis TPC1-EGFP and human TPC2-EGFP fusion proteins at the membrane of the large central vacuole. Bath (cytosolic) application of either NAADP or PI(3,5)P2 did not affect the voltage- and calcium-dependent characteristics of AtTPC1-EGFP. By contrast, PI(3,5)P2 elicited large sodium currents in hTPC2-EGFP-containing vacuoles, while NAADP had no such effect. Analogous results were obtained when PI(3,5)P2 was applied to hTPC2 expressed in baker’s yeast giant vacuoles. Our results underscore the fundamental differences in the mode of current activation and ion selectivity between animal and plant TPC proteins and corroborate the PI(3,5)P2-mediated activation and Na+ selectivity of mammalian TPC2.  相似文献   
4.
We have used a novel quantitative trait locus model to study the genetics of survival of F2 progeny of susceptible BALB/cByJ and resistant C57BL/6ByJ mice that have been infected with Listeria monocytogenes. This allowed us to map modifiers of L. monocytogenes susceptibility to chromosomes 5 and 13.  相似文献   
5.
6.
7.
The paper presents an identification procedure for a dynamic model of am hydrologic process. The process involves solute transport in streams subject to aquifer interaction and unsteady flows and the intended use of the model is prediction. Detailed assumptions and results are provided to illustrate the level of comprehensive analysis required to assess model adequacy. The assessment procedure easily generalizes to any dynamic model which is linear-in-the-parameters. As a fundamental tool, instrumental variable algorithms can be adopted which have a number of attractive features. These algorithms make both model-order identification and specification among alternatives a straightforward task. They are known to be consistent estimators in the presence of a wide class of errors. It is seen that they can be made stable and robust in the presence of data outliers. Instrumental variable algorithms can also be used which are asymptotically efficient and provide a covariance matrix of parameter estimates. The paper shows how they aid the quantification of predictive uncertainty and investigates the validity of the underlying assumptions. Further, it illustrates that, when instrumental variable algorithms are used in recursive mode, they can be used not only as an additional tool to access model inadequacy but also as an aid to model improvements.  相似文献   
8.
Zusammenfassung Bei Ratten und Kaninchen, jedoch nicht bei Hunden und Katzen, konnten durch wiederholte Injektion von Angiotensin-II-Amid-Carbodiimid-Proteinkomplex in Freund'schem Adjuvans zirkulierende Antikörper gegen Angiotensin erzeugt werden. Durch diese Immunisierung wurde die pressorische Wirkung von exogenem Angiotensin aufgehoben bzw. abgeschwächt, während die von Noradrenalin oder Vasopressin unbeeinflusst blieb. Der Reningehalt der Nieren von Ratten und Kaninchen wurde durch die Immunisierung nicht verändert.  相似文献   
9.
10.
It is a firm prediction of the concordance cold-dark-matter cosmological model that galaxy clusters occur at the intersection of large-scale structure filaments. The thread-like structure of this 'cosmic web' has been traced by galaxy redshift surveys for decades. More recently, the warm–hot intergalactic medium (a sparse plasma with temperatures of 10(5) kelvin to 10(7) kelvin) residing in low-redshift filaments has been observed in emission and absorption. However, a reliable direct detection of the underlying dark-matter skeleton, which should contain more than half of all matter, has remained elusive, because earlier candidates for such detections were either falsified or suffered from low signal-to-noise ratios and unphysical misalignments of dark and luminous matter. Here we report the detection of a dark-matter filament connecting the two main components of the Abell 222/223 supercluster system from its weak gravitational lensing signal, both in a non-parametric mass reconstruction and in parametric model fits. This filament is coincident with an overdensity of galaxies and diffuse, soft-X-ray emission, and contributes a mass comparable to that of an additional galaxy cluster to the total mass of the supercluster. By combining this result with X-ray observations, we can place an upper limit of 0.09 on the hot gas fraction (the mass of X-ray-emitting gas divided by the total mass) in the filament.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号