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   2062篇
  免费   120篇
  国内免费   1篇
电工技术   13篇
化学工业   402篇
金属工艺   17篇
机械仪表   31篇
建筑科学   94篇
矿业工程   7篇
能源动力   31篇
轻工业   295篇
水利工程   14篇
石油天然气   4篇
无线电   96篇
一般工业技术   250篇
冶金工业   590篇
原子能技术   5篇
自动化技术   334篇
  2024年   7篇
  2023年   21篇
  2022年   55篇
  2021年   90篇
  2020年   42篇
  2019年   47篇
  2018年   68篇
  2017年   72篇
  2016年   70篇
  2015年   48篇
  2014年   71篇
  2013年   109篇
  2012年   122篇
  2011年   93篇
  2010年   91篇
  2009年   89篇
  2008年   105篇
  2007年   72篇
  2006年   48篇
  2005年   44篇
  2004年   46篇
  2003年   42篇
  2002年   49篇
  2001年   28篇
  2000年   18篇
  1999年   25篇
  1998年   151篇
  1997年   93篇
  1996年   54篇
  1995年   40篇
  1994年   33篇
  1993年   29篇
  1992年   19篇
  1991年   9篇
  1990年   13篇
  1989年   11篇
  1988年   12篇
  1987年   14篇
  1986年   10篇
  1985年   10篇
  1984年   14篇
  1983年   12篇
  1982年   6篇
  1981年   8篇
  1979年   6篇
  1978年   7篇
  1977年   9篇
  1976年   11篇
  1975年   7篇
  1974年   6篇
排序方式: 共有2183条查询结果,搜索用时 31 毫秒
111.
112.
Seeko'o旅馆位于法国波尔多市北部的夏特隆区(Chartrons),美丽的加伦河(Garonne)左岸,Quai de Bacalan街与Cours EdouardVaillant街的交叉口.  相似文献   
113.
This article proposes an analytical model for evaluating the number of simultaneous communications that can be sustained by an ad-hoc network in which the nodes are equipped with fully adaptive smart antennas. The presented mathematical framework adopts realistic models for the antenna radiation pattern and the channel behavior, and is able to take into account the network topology and the characteristics of the medium access control (MAC) protocol in the spatial domain. The model is employed to investigate the impact of the spatial channel model and of the angular spread on network performance. Additionally, this article examines the influence of the transmission policy of the control and data packets of the MAC layer on the number of simultaneous communications.  相似文献   
114.
The population dynamics of micro-organisms during grape-must fermentation has been thoroughly studied. However, the main approach has relied on microbiological methods based on plating. This approach may overlook micro-organisms that (i) grow slowly or do not grow well on artificial media or (ii) whose population size is small enough to be detected by regular sampling. Culture-independent methods have been used and compared with the traditional plating method during wine fermentations performed at two different temperatures (13 °C and 25 °C). These methods include a qualitative technique, the DGGE; a semi-quantitative technique, the direct cloning of amplified DNA; and a quantitative technique, the QPCR. The biodiversity observed in the must and at the beginning of fermentation was much higher when DGGE or direct cloning were used. Quantification of the most frequent non-Saccharomyces yeast, Hanseniaspora uvarum and Candida zemplinina, showed that they survived throughout the fermentation process and, specifically, it revealed the quantitatively relevant presence of C. zemplinina until the end of fermentation.  相似文献   
115.
The familiar question, "Who is the client?" has become a distraction from more important ethical questions. By requiring a singular answer, the question obscures the fact that psychologists have ethical obligations toward every party in a case, no matter how many or how named. Making the question plural is not a sufficient solution, because identifying the client(s) should not be treated as an end in itself; it is simply a means of clarifying the nature of the relationship(s) and understanding the accompanying ethical obligations. After exploring the underlying implications for informed consent, confidentiality, and other ethical duties, the author suggests that psychologists adopt an alternative ethical question: "What are my ethical responsibilities to each of the parties in this case?" Finally, a case example illustrates the fact that the old question has several different meanings (and therefore different answers), depending upon whether it is asked as an ethical, clinical, legal, or reimbursement question. The proposed new question avoids such confusion because it is easily identifiable as an ethical question and its meaning is clear. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
116.
117.
118.
欧洲化学品管理局(ECHA)现已将重铬酸盐列入了高关注物质(SVHC)的名单.用含有重铬酸钾和重铬酸钠等的媒介染料染制羊毛的工厂正面临着越来越大的压力.这意味着采用这种技术的染厂未来可能要得到特别授权才能使用这种化学品.  相似文献   
119.
This article reviews the current bibliographic knowledge on early neurobehavioral development and milestones in Fragile X syndrome (FraX), with emphasis on males affected by the condition. Three broad areas of early development were examined: (1) gross and fine motor, (2) speech and language, and (3) social. The result of the current review indicates very limited information on the developmental milestones in all three areas. The scarce literature on motor development shows that in FraX there is an early developmental delay. Research on speech and language demonstrates pervasive deficits in conversational skills and severe developmental delay, with increasing discrepancy between language level and chronological age in young males with FraX. Finally, deficits in social development in FraX include abnormal gaze, approach and avoidance conflict, and high incidence of autistic spectrum disorders.  相似文献   
120.
Thermally induced protein unfolding/folding processes have been studied on alpha-lactalbumin and alpha-apolactalbumin. Experiments monitored by fluorescence and circular dichroism spectroscopic techniques on alpha-apolactalbumin showed the formation of an intermediate species, whereas in the case of alpha-lactalbumin, this intermediate species was not detected. The presence and resolution of this intermediate species, its spectrum, and the evolution of all conformations during protein unfolding/folding processes were estimated using the multivariate curve resolution-alternating least-squares method. Elucidation of the nature and contribution of the different secondary structure motifs in each of the resolved protein conformations, including the intermediate, was also carried out. Multivariate resolution has shown to be an excellent tool for the complete characterization of all protein conformations involved in folding processes, including intermediate species that cannot be isolated by physical or chemical means. Indeed, it is in the determination and modeling of these intermediates that this chemometric approach outperforms in power and reliability previous methodologies based on simpler measurements and data treatments and fills the void linked to the elucidation and interpretation of complex mechanisms in protein folding processes.  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