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   299篇
  免费   8篇
  国内免费   1篇
  2022年   6篇
  2021年   2篇
  2020年   3篇
  2019年   2篇
  2018年   6篇
  2017年   6篇
  2016年   9篇
  2015年   20篇
  2014年   13篇
  2013年   21篇
  2012年   11篇
  2011年   24篇
  2010年   6篇
  2009年   8篇
  2008年   21篇
  2007年   15篇
  2006年   18篇
  2005年   17篇
  2004年   18篇
  2003年   14篇
  2002年   21篇
  2001年   4篇
  2000年   2篇
  1999年   5篇
  1998年   1篇
  1997年   1篇
  1994年   5篇
  1993年   1篇
  1992年   2篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1987年   3篇
  1985年   2篇
  1984年   1篇
  1981年   3篇
  1979年   2篇
  1977年   2篇
  1976年   3篇
  1975年   1篇
  1967年   1篇
  1964年   1篇
  1963年   2篇
  1959年   1篇
  1958年   1篇
排序方式: 共有308条查询结果,搜索用时 15 毫秒
1.
The nucleotide sequences of rbcL genes encoding the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) were determined from six species of Prymnesiophyta to clarify their phylogenetic relationships. Molecular phylogenetic trees were constructed using PAUP (Phylogenetic Analysis Using Parsimony). These analyses suggest that the Prymnesiophyta, except for the Pavlovales, area relatively stable monophyletic group. Pleurochrysis carterae, included in the Isochrysidales, is a sister species of a monophyletic group consisting of other members of the Isochrysidales, Gephyrocapsa oceanica and Emiliania huxleyi, members of the Coccosphaerales, Calyptrosphaera sphaeroidea and Umbilicosphaera sibogae var. foliosa, and a member of the Prymnesiales, Chrysochromulina hirta. The nucleotide sequence of rbcL from G. oceanica was identical to that from E. huxleyi within the region examined. Our trees show that G. oceanica and E. huxleyi are more closely related to C. hirta than to U. sibogae, C. sphaeroidea, and P. carterae. These results suggest that orders in the Prymnesiophyceae, including the above-mentioned genera, should be redefined.  相似文献   
2.
3.
We describe a new technique for immunohistochemical and enzyme-histochemi-cal double staining using confocal laser scanning microscopy in the reflection mode. As an example, we investigated the immunoreactivity for Spot 35-calbindin-D28K, a vitamin D-dependent calcium binding protein, and the enzyme activity for ma+-ATPase in the rat kidney. The lead precipitation method for Ca2+-ATPase was initially used to process kidney slices. Each specimen was then dehydrated and embedded in a water soluble resin. Thin sections were cut from the resin block, and an indirect immunocolloidal gold method with silver enhancement for Spot 35-calbindin-D28K antigen was carried out on the glass slides. Results were then observed by confocal laser scanning microscopy in the reflection mode. The three-dimensional distribution of the reaction products was detected by serial optic slice images. Lead phosphate particles, which represented the location of Ca2+-ATPase, were distributed deep in the section. The most intense signals from the silver partkles were detected from the surface slice of the section. A stereoscopic image generated from the serial optic slices clearly showed the differences in their distribution.  相似文献   
4.
The hypothesis that chronic competitive antagonism of nicotinic acetylcholine receptors (nAChR), even in the absence of immobilization or paralysis, induces proliferation of the receptor and tolerance to the competitive antagonist was tested. Chronic antagonism of the nAChR was achieved in rats by an infusion of d-tubocurarine (dTC) via subcutaneously placed osmotic pumps. After 2 wk of dTC or saline, the neuromuscular pharmacodynamics and nAChR number were examined. No differences in weight gain or mobility were observed between groups. Chronic dTC infusion at 2 wk resulted in a baseline concentration of 0.41 +/- 0.07 (SE) micrograms/ml, which, if achieved acutely, would cause a depression of the twitch tension to 60% of control twitch height. Moreover the experimental group was able to develop a baseline twitch tension of 50 g, similar to that of controls. Despite the baseline dTC concentration in the experimental group, the effective doses of dTC for twitch depression were similar to those of controls. The plasma dTC concentration required for steady-state twitch inhibition was significantly (P less than 0.05) higher in the experimental group (0.83 +/- 0.04 vs. 0.50 +/- 0.15 micrograms/ml) as were the extrajunctional nAChR (19.76 +/- 1.77 vs. 13.37 +/- 1.82 fmol/mg protein). The diaphragmatic nAChR were unaltered. This study confirms that chronic doses of dTC cause tolerance to its effects and proliferation of nAChR even in the absence of immobilization. The absence of nAChR changes in the diaphragm may be due to the higher margin of safety of the diaphragm for muscle relaxants than for peripheral muscles. Intensive Care Unit patients receiving chronic infusions of dTC to facilitate mechanical ventilation will require increased doses with time.  相似文献   
5.
We have developed and characterized 21 microsatellite markers in the aphidophagous gall midge Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae). All 21 loci tested were polymorphic: the number of alleles ranged from 2 to 17. Allelic richness and observed heterozygosities were higher in females than in males. Several loci had no heterozygosity in males, suggesting that the loci were located on sex chromosomes or E-chromosomes, common to cecidomyiids. The high polymorphism detected in this study suggests the markers will be of value in analyzing genetic structure of field populations.  相似文献   
6.
7.
Sleep and Biological Rhythms - This study aimed to assess the success of the Japanese government’s “Early to bed, early to rise, and don’t forget your breakfast” (EB, ER,...  相似文献   
8.
In this paper we present SNUAGE, a platform-as-a-service security framework for building secure and scalable multi-layered services based on the cloud computing model. SNUAGE ensures the authenticity, integrity, and confidentiality of data communication over the network links by creating a set of security associations between the data-bound components on the presentation layer and their respective data sources on the data persistence layer. SNUAGE encapsulates the security procedures, policies, and mechanisms in these security associations at the service development stage to form a collection of isolated and protected security domains. The secure communication among the entities in one security domain is governed and controlled by a standalone security processor and policy attached to this domain. This results into: (1) a safer data delivery mechanism that prevents security vulnerabilities in one domain from spreading to the other domains and controls the inter-domain information flow to protect the privacy of network data, (2) a reusable security framework that can be employed in existing platform-as-a-service environments and across diverse cloud computing service models, and (3) an increase in productivity and delivery of reliable and secure cloud computing services supported by a transparent programming model that relieves application developers from the intricate details of security programming. Last but not least, SNUAGE contributes to a major enhancement in the energy consumption and performance of supported cloud services by providing a suitable execution container in its protected security domains for a wide suite of energy- and performance-efficient cryptographic constructs such as those adopted by policy-driven and content-based security protocols. An energy analysis of the system shows, via real energy measurements, major savings in energy consumption on the consumer devices as well as on the cloud servers. Moreover, a sample implementation of the presented security framework is developed using Java and deployed and tested in a real cloud computing infrastructure using the Google App Engine service platform. Performance benchmarks show that the proposed framework provides a significant throughput enhancement compared to traditional network security protocols such as the Secure Sockets Layer and the Transport Layer Security protocols.  相似文献   
9.
Kano  Rui  Kimura  Utako  Kakurai  Maki  Hiruma  Junichiro  Kamata  Hiroshi  Suga  Yasushi  Harada  Kazutoshi 《Mycopathologia》2020,185(6):947-958
Mycopathologia - In this report, we describe the first isolation of two highly terbinafine (TRF)-resistant Trichophyton interdigitale-like strains from a Nepali patient and an Indian patient with...  相似文献   
10.
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