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   1916篇
  免费   94篇
  国内免费   2篇
电工技术   53篇
化学工业   559篇
金属工艺   16篇
机械仪表   47篇
建筑科学   51篇
矿业工程   3篇
能源动力   85篇
轻工业   245篇
水利工程   2篇
石油天然气   10篇
无线电   175篇
一般工业技术   353篇
冶金工业   88篇
原子能技术   11篇
自动化技术   314篇
  2024年   2篇
  2023年   20篇
  2022年   104篇
  2021年   116篇
  2020年   52篇
  2019年   51篇
  2018年   56篇
  2017年   36篇
  2016年   66篇
  2015年   70篇
  2014年   75篇
  2013年   152篇
  2012年   129篇
  2011年   132篇
  2010年   117篇
  2009年   87篇
  2008年   83篇
  2007年   86篇
  2006年   76篇
  2005年   56篇
  2004年   58篇
  2003年   48篇
  2002年   47篇
  2001年   21篇
  2000年   24篇
  1999年   24篇
  1998年   40篇
  1997年   31篇
  1996年   25篇
  1995年   22篇
  1994年   18篇
  1993年   14篇
  1992年   10篇
  1991年   10篇
  1990年   5篇
  1989年   5篇
  1988年   4篇
  1987年   4篇
  1986年   4篇
  1985年   6篇
  1983年   2篇
  1982年   4篇
  1981年   2篇
  1980年   2篇
  1979年   3篇
  1975年   2篇
  1973年   1篇
  1972年   4篇
  1971年   2篇
  1965年   1篇
排序方式: 共有2012条查询结果,搜索用时 19 毫秒
1.
Here we report some recent biophysical issues on the preparation of solute-filled lipid vesicles and their relevance to the construction of “synthetic cells.” First, we introduce the “semi-synthetic minimal cells” as the liposome-based cell-like systems, which contain a minimal number of biomolecules required to display simple and complex biological functions. Next, we focus on recent aspects related to the construction of synthetic cells. Emphasis is given to the interplay between the methods of synthetic cell preparation and the physics of solute encapsulation. We briefly introduce the notion of structural and compositional “diversity” in synthetic cell populations.  相似文献   
2.
E-democracy, the design and development of new techniques for improving communication between public administration and citizens, is a major application field for natural language processing and language engineering. Helping citizens access information in a friendly, intuitive way is the primary objective of a global e-democracy framework. The E-democracy European Network project (EDEN) aimed at discovering whether a particular NLP (natural language processing) approach could further e-democracy by increasing citizens' participation in the decision-making process. The goal was twofold: to test whether e-democracy requirements could be meet using advanced linguistic technology and to test whether augmented phrase structure grammars (APSGs) were robust and well-assessed enough to use in a real-world environment. Also, the aim is to develop two toolsets to improve communication between PAs and citizens in the context of urban planning: a set of NLP-based tools to simplify access to information and knowledge and a set of forum and polling devices  相似文献   
3.
A number of retinal proteins are phosphorylated by a variety of kinases, resulting in well-known regulatory effects. The identity and role of corresponding phosphatases is less clear. We simultaneously measured the activity of serine/ threonine protein phosphatases type 1, 2A and 2C in bovine retinae. The enzymes were classified according to substrate specificity, divalent cation requirement and the effect of phosphatase subtype-specific inhibitors. The total- and specific activity of phosphatase type 2A was prevalent. Type 2C was 10-fold less abundant. 80% of type 1 and 50% of type 2A and type 2C, respectively, were soluble. An economic purification scheme was developed. We demonstrated the presence of phosphatase isozymes 2Calpha and 2Cbeta in bovine rod outer segments by enzymatic analysis as well as immunological techniques. The results suggest a yet unknown role of phosphatase type 2C in phototransduction. On the other hand, the immense amount of protein phosphatases found to be soluble - therefore not associated with rod outer segment membranes - points towards participation of these enzymes in the process of visual transduction not considered thus far.  相似文献   
4.
5.
The last decade has seen the development of a number of approaches for estimating those variables which are difficult to measure on-line in industrial process situations. Whilst a range of techniques is available, a common element is the use of process knowledge in the form of a system model. In the case of bioprocess systems, although a large range of models has been presented in the literature, their use in estimation schemes on an industrial scale has been limited. A number of reasons can be identified for their low level of utilisation. Of particular significance is the uncertainty which exists in quantifying system performance and the process-model mismatch which inevitably results. The level of ‘pre-defined model’ uncertainty, together with the knowledge gained during the course of the fermentation, serves to dictate estimator structure. The paper considers a range of estimation strategies and contrasts, through industrial applications, their performance characteristics and utility.  相似文献   
6.
In healthcare facilities most of the daily activities require strict coordination between clinicians, who often operate under heavy workloads and minimal workforce conditions in environments filled with increasingly complex technology. Ubiquitous Computing applications constitute a suitable solution for both reducing medical costs and improving patient safety by better supporting clinical processes. In this study we introduce an intelligent infrastructure for smart hospitals which implements basic services to optimize medical staff/patient interactions and grants ubiquitous and transparent access to clinical data stored in standard clinical databases. This infrastructure relies on the integration of Radio Frequency IDentification (RFID) and photosensor technologies to identify, locate and track clinicians and patients equipped with mobile devices and wearable RFID tags.  相似文献   
7.
Interleukin (IL)-33 is a member of the interleukin (IL)-1 family of cytokines linked to the development of inflammatory conditions and cancer in the gastrointestinal tract. This study is designed to investigate whether IL-33 has a direct effect on human gastric epithelial cells (GES-1), the human gastric adenocarcinoma cell line (AGS), and the gastric carcinoma cell line (NCI-N87) by assessing its role in the regulation of cell proliferation, migration, cell cycle, and apoptosis. Cell cycle regulation was also determined in ex vivo gastric cancer samples obtained during endoscopy and surgical procedures. Cell lines and tissue samples underwent stimulation with rhIL-33. Proliferation was assessed by XTT and CFSE assays, migration by wound healing assay, and apoptosis by caspase 3/7 activity assay and annexin V assay. Cell cycle was analyzed by means of propidium iodine assay, and gene expression regulation was assessed by RT-PCR profiling. We found that IL-33 has an antiproliferative and proapoptotic effect on cancer cell lines, and it can stimulate proliferation and reduce apoptosis in normal epithelial cell lines. These effects were also confirmed by the analysis of cell cycle gene expression, which showed a reduced expression of pro-proliferative genes in cancer cells, particularly in genes involved in G0/G1 and G2/M checkpoints. These results were confirmed by gene expression analysis on bioptic and surgical specimens. The aforementioned results indicate that IL-33 may be involved in cell proliferation in an environment- and cell-type-dependent manner.  相似文献   
8.
9.
We propose a stochastic disease model where vaccination is included and such that the immunity is permanent. The existence, uniqueness, and positivity of the solution and the stability of the disease-free equilibrium are studied.  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