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   113篇
  免费   5篇
电工技术   2篇
化学工业   11篇
建筑科学   3篇
能源动力   6篇
轻工业   6篇
水利工程   1篇
无线电   39篇
一般工业技术   11篇
冶金工业   31篇
自动化技术   8篇
  2020年   4篇
  2019年   2篇
  2018年   4篇
  2017年   4篇
  2016年   2篇
  2015年   1篇
  2014年   1篇
  2013年   2篇
  2011年   2篇
  2010年   2篇
  2009年   3篇
  2008年   2篇
  2007年   4篇
  2006年   4篇
  2005年   3篇
  2004年   8篇
  2003年   3篇
  2002年   9篇
  2001年   5篇
  1999年   2篇
  1998年   6篇
  1997年   3篇
  1996年   5篇
  1995年   7篇
  1994年   11篇
  1993年   7篇
  1992年   1篇
  1986年   4篇
  1984年   1篇
  1983年   1篇
  1981年   1篇
  1977年   1篇
  1976年   3篇
排序方式: 共有118条查询结果,搜索用时 15 毫秒
1.
Health care spending in the United States outpaces all other nations or 14% of the gross domestic product. Although the escalating increases in health care costs which have characterized the industry over the past quarter century have begun to slow down, if changes in the current health care policy are not implemented, spending is expected to increase at a rate of 11.5% during each of the next 5 years. Health care spending will reach $1.1 trillion or 15% of the gross domestic product in the near future. Both hospitals and universities are facing mounting pressures to reduce their costs and improve their services. In this environment, it becomes increasingly important for directors of nurse anesthesia programs to financially justify their existence. This discussion begins with a brief overview of nurse anesthesia education in the United States. The value of and need for nurse anesthetists in the US health care system is addressed. Advantages and disadvantages of hospital versus university-based programs are highlighted and funding sources identified. Future needs and challenges in nurse anesthesia education conclude this discussion.  相似文献   
2.
The small subunit (SSU) and the internal transcribed spacer (ITS) of nuclear ribosomal DNA genes from 27 specimens of the fungal genera Gremmeniella and Ascocalyx were amplified by PCR. Length polymorphisms were observed in the SSU and allowed the differentiation of four groups among the isolates tested: (i) Ascocalyx abietis; (ii) Gremmeniella isolates from Picea spp.; (iii) Gremmeniella isolates from Abies balsamea; and (iv) Gremmeniella isolates from Abies sacchalinensis, Larix spp., and Pinus spp. The amplified ITS was the same length for all Gremmeniella specimens and was 60 bp longer in A. abietis. Phylogenetic analysis of length polymorphisms and of 24 restriction sites in the SSU and ITS showed that Gremmeniella isolates were more related to each other than to the Ascocalyx isolate. Furthermore, seven groups were evident within the genus Gremmeniella. Our results confirm that Gremmeniella and Ascocalyx should be kept as different taxa and suggest that the taxonomy of the former could be revised to consider isolates from Abies balsamea and from Picea spp. to be two different varieties while incorporating Gremmeniella laricina into G. abietina, as a new variety.  相似文献   
3.
BACKGROUND: Exogenous antigenic peptides are presented to T cells by class II major histocompatibility complex (Ia) molecules on the surface of antigen-presenting cells. Class II-associated invariant chain (Ii) is also required for effective antigen presentation. Because messenger RNAs (mRNAs) for Ii chain and for class II I-A beta chain appear in the mouse intestinal epithelium after weaning, experiments were conducted to test the effect of age of weaning and diet on the appearance of Ia and Ii mRNA. METHODS: Four litters were split at day 17; one half was weaned and the other remained with the mother until day 24. On day 23, 25, 27, and 29, enterocytes were isolated from full-length small intestine by vascular perfusion with 30 mmol/L ethylenediaminetetraacetic acid, and the RNA was extracted. RESULTS: Appearance of Ii and I-A beta was significantly delayed by late weaning, as judged by RNA hybridization blots (Ii chain) and complementary DNA amplification (I-A beta chain). In mice on elemental diets, the appearance of Ii and I-A beta chain was delayed compared with littermates reared on standard chow. Ii mRNA failed to appear in mice maintained on the elemental diet by day 40, despite normal growth. CONCLUSIONS: Appearance of mRNA for both Ia and Ii depends on the introduction of a complex diet and not the "stress" of weaning or elimination of breast milk. Introduction of foreign dietary antigens or development of an altered intestinal flora may contribute to this process.  相似文献   
4.
Past behavior guides future responses through 2 processes. Well-practiced behaviors in constant contexts recur because the processing that initiates and controls their performance becomes automatic. Frequency of past behavior then reflects habit strength and has a direct effect on future performance. Alternately, when behaviors are not well learned or when they are performed in unstable or difficult contexts, conscious decision making is likely to be necessary to initiate and carry out the behavior. Under these conditions, past behavior (along with attitudes and subjective norms) may contribute to intentions, and behavior is guided by intentions. These relations between past behavior and future behavior are substantiated in a meta-analytic synthesis of prior research on behavior prediction and in a primary research investigation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
5.
Despite advances in anesthetic technique and technology, intraoperative awareness continues to occur with alarming regularity. The psychological effects on patients and the medicolegal consequences to providers have created the need for a reliable monitor of the hypnotic component of anesthesia. A new technology known as bispectral analysis (BIS) has the potential to put an end to the devastating occurrence of intraoperative awareness, as well as improve the overall effectiveness of anesthetic delivery and the surgical experience. Applicable to almost any situation requiring sedation or general anesthesia, BIS's reliability is a real-time measure of hypnosis levels.  相似文献   
6.
We describe in this paper a new TCP ACK pacing scheme that dynamically tunes its behavior to account for variations or changes in the network load. The scheme does not require the knowledge of when TCP is in the slow‐start or congestion avoidance phase to determine the proper ACK pacing rate. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
7.
This paper describes an overload control scheme for web servers which integrates admission control and load balancing. The admission control mechanism adaptively determines the client request acceptance rate to meet the web servers' performance requirements while the load balancing or client request distribution mechanism determines the fraction of requests to be assigned to each web server. The scheme requires no prior knowledge of the relative speeds of the web servers, nor the work required to process each incoming request. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
8.
Leishmania resistant to arsenicals and antimonials extrude arsenite. Previous results of arsenite uptake into plasma membrane-enriched vesicles suggested that the transported species is a thiol adduct of arsenite. In this paper, we demonstrate that promastigotes of arsenite-resistant Leishmania tarentolae have increased levels of intracellular thiols. High-pressure liquid chromatography of the total thiols showed that a single peak of material was elevated almost 40-fold. The major species in this peak was identified by matrix-assisted laser desorption/ionization mass spectrometry as N1,N8-bis-(glutathionyl)spermidine (trypanothione). The trypanothione adduct of arsenite was effectively transported by the As-thiol pump. No difference in pump activity was observed in wild type and mutants. A model for drug resistance is proposed in which Sb(V)/As(V)-containing compounds, including the antileishmanial drug Pentostam, are reduced intracellularly to Sb(III)/As(III), conjugated to trypanothione, and extruded by the As-thiol pump. The rate-limiting step in resistance is proposed to be formation of the metalloid-thiol pump substrates, so that increased synthesis of trypanothione produces resistance. Increased synthesis of the substrate rather than an increase in the number of pump molecules is a novel mechanism for drug resistance.  相似文献   
9.
Relative service differentiation refers to service models that provide assurances for the relative quality ordering between classes, rather than for the absolute service level in each class. An example is the proportional differentiation model which provides a way to control the quality spacing between classes locally at each hop. In this model, certain forwarding metrics are ratioed proportional to the class differentiation parameters that the network operator chooses. In this paper, we propose a new proportional loss rate differentiation mechanism that integrates relative loss rate differentiation directly into active queue management using random early detection. Copyright © 2004 John Wiley &Sons, Ltd.  相似文献   
10.
In this paper, a high-speed image sensor with very high sensitivity is developed. The high sensitivity is achieved by introduction of backside illumination and charge-carrier multiplication (CCM). The high frame rate is guaranteed by installing the in situ storage image sensor (ISIS) structure on the front side. A test sensor of the BSI-ISIS has been developed and evaluated. It is shown that an image with a very low signal level embedded under the noise floor is recognizable by activating the CCM.  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