全文获取类型
收费全文 | 3038篇 |
免费 | 179篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 25篇 |
综合类 | 3篇 |
化学工业 | 560篇 |
金属工艺 | 38篇 |
机械仪表 | 72篇 |
建筑科学 | 132篇 |
矿业工程 | 5篇 |
能源动力 | 78篇 |
轻工业 | 223篇 |
水利工程 | 32篇 |
石油天然气 | 6篇 |
武器工业 | 1篇 |
无线电 | 252篇 |
一般工业技术 | 657篇 |
冶金工业 | 505篇 |
原子能技术 | 12篇 |
自动化技术 | 618篇 |
出版年
2024年 | 5篇 |
2023年 | 26篇 |
2022年 | 54篇 |
2021年 | 75篇 |
2020年 | 58篇 |
2019年 | 66篇 |
2018年 | 94篇 |
2017年 | 88篇 |
2016年 | 84篇 |
2015年 | 81篇 |
2014年 | 130篇 |
2013年 | 214篇 |
2012年 | 209篇 |
2011年 | 283篇 |
2010年 | 202篇 |
2009年 | 219篇 |
2008年 | 188篇 |
2007年 | 196篇 |
2006年 | 153篇 |
2005年 | 142篇 |
2004年 | 99篇 |
2003年 | 85篇 |
2002年 | 75篇 |
2001年 | 44篇 |
2000年 | 39篇 |
1999年 | 42篇 |
1998年 | 38篇 |
1997年 | 37篇 |
1996年 | 20篇 |
1995年 | 20篇 |
1994年 | 11篇 |
1993年 | 16篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1974年 | 8篇 |
1973年 | 4篇 |
排序方式: 共有3219条查询结果,搜索用时 0 毫秒
101.
The discretized quadratic sub‐optimal tracker for nonlinear continuous two‐dimensional (2‐D) systems is newly proposed in this paper. The proposed method provides a novel methodology for indirect digital redesign for nonlinear continuous 2‐D systems with a continuous performance index. This includes the following features: (1) the 2‐D optimal‐linearization approach of the nonlinear 2‐D Roesser's model (RM), (2) the dynamic programming‐based discretized quadratic optimal tracker for linear continuous 2‐D systems, (3) the steady‐state discretized quadratic sub‐optimal tracker for linear continuous 2‐D systems, and (4) the discretized quadratic sub‐optimal tracker for nonlinear continuous 2‐D systems. Illustrative examples are presented to demonstrate the effectiveness of the proposed procedure. 相似文献
102.
Robert A. Carlton 《Scanning》1997,19(2):85-91
The objective of this investigation was to evaluate the practical effects of electron beam broadening in the environmental scanning electron microscope (ESEM) on particle x-ray microanalysis and to determine some of the optimum operating conditions for this type of analysis. Four sets of experiments were conducted using a Faraday cage and particles of copper, glass, cassiterite, andrutile. The accelerating voltage and chamber pressure varied from 20 to 10 kV and from 665–66 Pa (5.0 to 0.5 torr), respectively. The standard gaseous secondary electron detectors (GSED) and the long environmental secondary dectectors (ESD) for the ESEM were evaluated at different working distances. The effect of these parameters on the presence of artifact peaks was evaluated. The particles were mounted on carbon tape on an aluminum specimen mount and were analyzed individually and as a mixture. Substrate peaks were present in almost all of the spectra. The presence of neighboring particle peaks and the number of counts in these depended upon the operating conditions. In general, few of these peaks were observed with the long ESD detector at 19 mm working distance and at low chamber pressures. More peaks and counts were observed with a deviation from these conditions. The most neighboring peaks and counts were obtained with the GSED detector at 21.5 mm working distance, 10 kV accelerating voltage, and 665 Pa (5.0 torr) chamber pressure. The results of these experiments support the idea that the optimum instrumental operating conditions for EDS analysis in the ESEM occur by minimizing the gas path length and the chamber water vapor pressure, and by maximizing the accelerating voltage. The results suggest that the analyst can expect x-ray counts from the mounting materials. These tests strongly support the recommendation of the manufacturer to use the long ESD detector and a 19 mm working distance for EDS analysis. The results of these experiments indicate that neighboring particles millimeters from the target may contribute x-ray counts to the spectrum. 相似文献
103.
Diefendorff James M.; Erickson Rebecca J.; Grandey Alicia A.; Dahling Jason J. 《Canadian Metallurgical Quarterly》2011,16(2):170
Emotional labor theory has conceptualized emotional display rules as shared norms governing the expression of emotions at work. Using a sample of registered nurses working in different units of a hospital system, we provided the first empirical evidence that display rules can be represented as shared, unit-level beliefs. Additionally, controlling for the influence of dispositional affectivity, individual-level display rule perceptions, and emotion regulation, we found that unit-level display rules are associated with individual-level job satisfaction. We also showed that unit-level display rules relate to burnout indirectly through individual-level display rule perceptions and emotion regulation strategies. Finally, unit-level display rules also interacted with individual-level dispositional affectivity to predict employee use of emotion regulation strategies. We discuss how future research on emotional labor and display rules, particularly in the health care setting, can build on these findings. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
104.
Shaun C. Lee Karina K. C. Leung Audrey C. Y. Chung Elysia S. Y. Wong Katie L. Meehan Jason Y. K. Chan 《International journal of molecular sciences》2022,23(22)
Biomarkers are crucial in oncology, from detection and monitoring to guiding management and predicting treatment outcomes. Histological assessment of tissue biopsies is currently the gold standard for oropharyngeal cancers, but is technically demanding, invasive, and expensive. This systematic review aims to review current markers that are detectable in biofluids, which offer promising non-invasive alternatives in oropharyngeal carcinomas (OPCs). A total of 174 clinical trials from the PubMed search engine in the last 5 years were identified and screened by 4 independent reviewers. From these, 38 eligible clinical trials were found and subsequently reviewed. The biomarkers involved, categorized by human papillomavirus (HPV)-status, were further divided according to molecular and cellular levels. Recent trials investigating biomarkers for both HPV-positive and HPV-negative OPCs have approaches from various levels and different biofluids including plasma, oropharyngeal swabs, and oral rinse. Promising candidates have been found to aid in detection, staging, and predicting prognosis, in addition to well-established factors including HPV-status, drinking and smoking status. These studies also emphasize the possibility of enhancing prediction results and increasing statistical significance by multivariate analyses. Liquid biopsies offer promising assistance in enhancing personalized medicine for cancer treatment, from lowering barriers towards early screening, to facilitating de-escalation of treatment. However, further research is needed, and the combination of liquid biopsies with pre-existing methods, including in vivo imaging and invasive techniques such as neck dissections, could also be explored in future trials. 相似文献
105.
M M Shabot P D Carlton S Sadoff L Nolan-Avila 《Computer methods and programs in biomedicine》1986,22(1):111-116
The use of computers for critical care data management may markedly increase the volume of digital numbers presented to the nurse and clinician. Such digital displays and reports may not be optimum for estimating the graded levels of intervention required for specific physiologic problems. We have devised software subsystems which allow for rapid configuration of medically oriented graphical reports and video images, using an English language syntax rather than specific computer code. These subsystems produce graphical reports which resemble previous hand-written charts, and video displays which are useful for hemodynamic patient management. 相似文献
106.
Neelam Soundarajan Jason O. Hallstrom Guoqiang Shu Adem Delibas 《Innovations in Systems and Software Engineering》2008,4(1):71-85
Design patterns are used extensively in the design of software systems. Patterns codify effective solutions for recurring design problems and allow software engineers to reuse these solutions, tailoring them appropriately to their particular applications, rather than reinventing them from scratch. In this paper, we consider the following question: How can system designers and implementers test whether their systems, as implemented, are faithful to the requirements of the patterns used in their design? A key consideration underlying our work is that the testing approach should enable us, in testing whether a particular pattern P has been correctly implemented in different systems designed using P, to reuse the common parts of this effort rather than having to do it from scratch for each system. Thus in the approach we present, corresponding to each pattern P, there is a set of pattern test case templates (PTCTs). A PTCT codifies a reusable test case structure designed to identify defects associated with applications of P in all systems designed using P. Next we present a process using which, given a system designed using P, the system tester can generate a test suite from the PTCTs for P that can be used to test the particular system for bugs in the implementation of P in that system. This allows the tester to tailor the PTCTs for P to the needs of the particular system by specifying a set of specialization rules that are designed to reflect the scenarios in which the defects codified in this set of PTCTs are likely to manifest themselves in the particular system. We illustrate the approach using the Observer pattern. 相似文献
107.
Detection of aircraft below the horizon for vision‐based detect and avoid in unmanned aircraft systems
下载免费PDF全文
![点击此处可从《野外机器人技术杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Vision‐based aircraft detection technology may provide a credible sensing option for automated detect and avoid in small‐to‐medium size fixed‐wing unmanned aircraft systems (UAS). Reliable vision‐based aircraft detection has previously been demonstrated in sky‐region sensing environments. This paper describes a novel vision‐based system for detecting aircraft below the horizon in the presence of ground clutter. We examine the performance of our system on a data set of 63 near collision encounters we collected between a camera‐equipped manned aircraft and a below‐horizon target. In these 63 encounters, our system successfully detects all aircraft, at an average detection range of 1890 m (with a standard error of 43 m and no false alarms in 1.1 h). Furthermore, our system does not require access to inertial sensor data (which significantly reduces system cost) and operates at over 12 frames per second. 相似文献
108.
The influence of plant lipids on the equilibrium sorption of three aromatic solutes from water was studied. The plant-water sorption isotherms of benzene, 1,2-dichlorobenzene, and phenanthrene were measured over a large range of solute concentrations using sealed vessels containing water, dried plant material, and solute. The plant materials studied include the shoots of annual rye, tall fescue, red fescue, and spinach as well as the roots of annual rye. Seven out of eight sorption isotherms were linear with no evidence of competitive effects between the solutes. For a given plant type, the sorption coefficient increased with decreasing solute water solubility. For a given solute, sorption increased with increasing plant lipid content. The estimated lipid-water partition coefficients of individual solutes were found to be significantly greater than the corresponding octanol-water partition coefficients. This indicates that plant lipids are a more effective partition solvent than octanol for the studied aromatic compounds. As expected, the solute lipid-water partition coefficients were log-linearly related to the respective water solubilities. For the compounds studied, partitioning into the lipids is believed to be the primary sorption mechanism. 相似文献
109.
110.
东京是一个捉摸不透的城市。从将要降落在成田机场的航班上看它,纵横阡陌的道路,排列整齐的房屋,黑白灰的色彩搭配,简单中富有层次,让我恍然想起了布莱克的石版画。那是以各种颜料,甚至各种肌理的布、纸拼贴的画面,没有过多的颜色重叠.沉静的中间色和原色恰如其分地协调其中,超凡脱俗。 相似文献