全文获取类型
收费全文 | 14896篇 |
免费 | 512篇 |
国内免费 | 50篇 |
专业分类
电工技术 | 165篇 |
综合类 | 23篇 |
化学工业 | 2685篇 |
金属工艺 | 285篇 |
机械仪表 | 260篇 |
建筑科学 | 902篇 |
矿业工程 | 56篇 |
能源动力 | 363篇 |
轻工业 | 1094篇 |
水利工程 | 171篇 |
石油天然气 | 119篇 |
武器工业 | 1篇 |
无线电 | 999篇 |
一般工业技术 | 2769篇 |
冶金工业 | 3093篇 |
原子能技术 | 94篇 |
自动化技术 | 2379篇 |
出版年
2023年 | 77篇 |
2022年 | 148篇 |
2021年 | 252篇 |
2020年 | 189篇 |
2019年 | 210篇 |
2018年 | 296篇 |
2017年 | 240篇 |
2016年 | 358篇 |
2015年 | 266篇 |
2014年 | 426篇 |
2013年 | 894篇 |
2012年 | 702篇 |
2011年 | 946篇 |
2010年 | 734篇 |
2009年 | 671篇 |
2008年 | 796篇 |
2007年 | 786篇 |
2006年 | 674篇 |
2005年 | 617篇 |
2004年 | 529篇 |
2003年 | 427篇 |
2002年 | 497篇 |
2001年 | 308篇 |
2000年 | 291篇 |
1999年 | 271篇 |
1998年 | 357篇 |
1997年 | 296篇 |
1996年 | 230篇 |
1995年 | 266篇 |
1994年 | 223篇 |
1993年 | 239篇 |
1992年 | 187篇 |
1991年 | 96篇 |
1990年 | 158篇 |
1989年 | 143篇 |
1988年 | 128篇 |
1987年 | 150篇 |
1986年 | 108篇 |
1985年 | 160篇 |
1984年 | 146篇 |
1983年 | 103篇 |
1982年 | 88篇 |
1981年 | 75篇 |
1980年 | 63篇 |
1979年 | 64篇 |
1978年 | 61篇 |
1977年 | 66篇 |
1976年 | 82篇 |
1974年 | 41篇 |
1973年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Abstract— Two measurement methods to characterize uniformity and the absolute cell gap of LCoS images will be reviewed. These are simple to use in a production environment and have allowed major improvements in manufacture to be achieved. For the purpose of this paper, the liquid‐crystal mode used is the 45° normally black mode. 相似文献
62.
Puttegowda Kiran Lehn David I. Park Jae H. Athanas Peter Jones Mark 《The Journal of supercomputing》2003,26(3):239-257
A distinguishing feature of reconfigurable computing over rapid prototyping is its ability to configure the computational fabric on-line while an application is running. Conventional reconfigurable computing platforms utilize commodity FPGAs, which typically have relatively long configuration times. Shrinking the configuration time down to the nanosecond region opens possibilities for rapid context switching and virtualizing the computational resources. An experimental context-switching FPGA, called the CSRC, has been created by BAE Systems, and gives researchers the opportunity to explore context-switching applications. This paper presents results obtained from constructing both control-driven and data-driven context switching applications on the CSRC device, along with unique properties of the run-time and compile-time environment. 相似文献
63.
Robyn Schinke Mark Greengrass Alexander M. Robertson Peter Willett 《Language Resources and Evaluation》1997,31(5):409-432
This paper reports a detailed evaluation of the effectiveness of a system that has been developed for the identification and
retrieval of morphological variants in searches of Latin text databases. A user of the retrieval system enters the principal
parts of the search term (two parts for a noun or adjective, three parts for a deponent verb, and four parts for other verbs),
this enabling the identification of the type of word that is to be processed and of the rules that are to be followed in determining
the morphological variants that should be retrieved. Two different search algorithms are described. The algorithms are applied
to the Latin portion of the Hartlib Papers Collection and to a range of classical, vulgar and medieval Latin texts drawn from
the Patrologia Latina and from the PHI Disk 5.3 datasets. The effectiveness of these searches demonstrates the effectiveness
of our procedures in providing access to the full range of classical and post-classical Latin text databases.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
64.
Prior theory and research suggests a positive relation between perceived victimization and overt anger. The authors proposed and tested a theoretical extension of this link by investigating possible moderating effects of individual and contextual variables. A sample of 158 employees of a municipality was used to test hypotheses that the relationship between perceived victimization and overt anger is moderated by hostile attributional style and perceptions of organizational norms. The results showed that the relation between perceptions of direct victimization and overt anger was stronger when the employee had a more rather than less hostile attributional style and when the employee perceived the organizational norms as more rather than less oppositional. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
65.
The piled raft is a geotechnical composite construction, consisting of the three elements piles, raft, and soil, which is applied for the foundation of tall buildings in an increasing number. In a parametric study, 259 different piled raft configurations have been analyzed by means of three-dimensional elastoplastic finite element analyses. In the study, the pile positions, the pile number, the pile length, and the raft-soil stiffness ratio as well as the load distribution on the raft has been varied. In the scope of this paper, the results of the parametric study are presented and design strategies for an optimized design of piled rafts subjected to nonuniform vertical loading are discussed. 相似文献
66.
67.
Dallen L. Andrew Hai‐Chao Han Juan Ocampo Adel Alaeddini Mark Thomsen 《Fatigue & Fracture of Engineering Materials & Structures》2021,44(1):101-114
Residual stress fields from cold expansion have been widely used to extend the fatigue life of aircraft structures. However, the spatial statistical character of these residual stress fields has not been established and has not been incorporated in current analysis methods. The objective of this study was to establish a spatial statistical method to quantify the residual stress field around a cold expanded hole. A framework called the Spatial Analysis of Residual Stress (SpARS) was developed utilizing spatial correlation, response surface modelling techniques and statistical resampling methods to characterize the residual stress field. Our results showed that tolerance bounds on residual stress can be quantified using this method. We also demonstrated the SpARS method using recently published round robin case studies. The newly developed model will be useful for aircraft structural fatigue crack growth analyses to incorporate residual stress fields for extending inspection intervals for fatigue and fracture critical structures. 相似文献
68.
Ajay Matta Muhammad Zia Karim Hoda Gerami Bettina Zoe Benigno Ivan Cheng Arne Mehrkens William Mark Erwin 《International journal of molecular sciences》2022,23(10)
Background: Tissue sources of pain emanating from degenerative discs remains incompletely understood. Canine intervertebral discs (IVDs) were needle puncture injured, 4-weeks later injected with either phosphate-buffered saline (PBS) or NTG-101, harvested after an additional fourteen weeks and then histologically evaluated for the expression of NGFr, BDNF, TrkB and CALCRL proteins. Quantification was performed using the HALO automated cell-counting scoring platform. Immunohistochemical analysis was also performed on human IVD tissue samples obtained from spinal surgery. Immunohistochemical analysis and quantification of neurotrophins and neuropeptides was performed using an in vivo canine model of degenerative disc disease and human degenerative disc tissue sections. Discs injected with NTG-101 showed significantly lower levels of Nerve Growth Factor receptor (NGFr/TrkA, p = 0.0001), BDNF (p = 0.009), TrkB (p = 0.002) and CALCRL (p = 0.008) relative to PBS injections. Human IVD tissue obtained from spinal surgery due to painful DDD show robust expression of NGFr, BDNF, TrkB and CALCRL proteins. A single intradiscal injection of NTG-101 significantly inhibits the expression of NGFr, BDNF, TrkB and CALCRL proteins in degenerative canine IVDs. These results strongly suggest that NTG-101 inhibits the development of neurotrophins that are strongly associated with painful degenerative disc disease and may have profound effects upon the management of patients living with discogenic pain. 相似文献
69.
Iwona Mazur-Michaek Katarzyna Kowalska Daniel Zielonka Marta Leniczak-Staszak Paulina Pietras Witold Szaflarski Mark Isalan Michal Mielcarek 《International journal of molecular sciences》2022,23(10)
Huntington’s disease (HD) is a fatal neurodegenerative disorder caused by a polyglutamine expansion in the huntingtin protein. HD-related pathological remodelling has been reported in HD mouse models and HD carriers. In this study, we studied structural abnormalities in the optic nerve by employing Spectral Domain Optical Coherence Tomography (SD-OCT) in pre-symptomatic HD carriers of Caucasian origin. Transmission Electron Microscopy (TEM) was used to investigate ultrastructural changes in the optic nerve of the well-established R6/2 mouse model at the symptomatic stage of the disease. We found that pre-symptomatic HD carriers displayed a significant reduction in the retinal nerve fibre layer (RNFL) thickness, including specific quadrants: superior, inferior and temporal, but not nasal. There were no other significant irregularities in the GCC layer, at the macula level and in the optic disc morphology. The ultrastructural analysis of the optic nerve in R6/2 mice revealed a significant thinning of the myelin sheaths, with a lamellar separation of the myelin, and a presence of myelonoid bodies. We also found a significant reduction in the thickness of myelin sheaths in peripheral nerves within the choroids area. Those ultrastructural abnormalities were also observed in HD photoreceptor cells that contained severely damaged membrane disks, with evident vacuolisation and swelling. Moreover, the outer segment of retinal layers showed a progressive disintegration. Our study explored structural changes of the optic nerve in pre- and clinical settings and opens new avenues for the potential development of biomarkers that would be of great interest in HD gene therapies. 相似文献
70.
Han F Wang Y Sims CE Bachman M Chang R Li GP Allbritton NL 《Analytical chemistry》2003,75(15):3688-3696
In the past decade, capillary electrophoresis has demonstrated increasing utility for the quantitative analysis of single cells. New applications for the analysis of dynamic cellular properties demand sampling methods with sufficient temporal resolution to accurately measure these processes. In particular, intracellular signaling pathways involving many enzymes can be modulated on subsecond time scales. We have developed a technique to rapidly lyse an adherent mammalian cell using a single electrical pulse followed by efficient loading of the cellular contents into a capillary. Microfabricated electrodes were designed to create a maximum voltage drop across the flattened cell's plasma membrane at a minimum interelectrode voltage. The influence of the interelectrode distance, pulse duration, and pulse strength on the rate of cell lysis was determined. The ability to rapidly lyse a cell and collect and separate the cellular contents was demonstrated by loading cells with Oregon Green and two isomers of carboxyfluorescein. All three fluorophores were detected with a separation efficiency comparable to that of standards. Parallel comparison of electrical lysis to that produced by a laser-based lysis system revealed that the sampling efficiencies of the two techniques were comparable. Rapid cell lysis by an electrical pulse may increase the application of capillary electrophoresis to the study of cellular dynamics requiring fast sampling times. 相似文献