全文获取类型
收费全文 | 8912篇 |
免费 | 477篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 143篇 |
综合类 | 19篇 |
化学工业 | 1987篇 |
金属工艺 | 205篇 |
机械仪表 | 176篇 |
建筑科学 | 361篇 |
矿业工程 | 28篇 |
能源动力 | 241篇 |
轻工业 | 803篇 |
水利工程 | 117篇 |
石油天然气 | 22篇 |
无线电 | 524篇 |
一般工业技术 | 1781篇 |
冶金工业 | 1646篇 |
原子能技术 | 40篇 |
自动化技术 | 1308篇 |
出版年
2023年 | 66篇 |
2022年 | 141篇 |
2021年 | 222篇 |
2020年 | 169篇 |
2019年 | 216篇 |
2018年 | 242篇 |
2017年 | 217篇 |
2016年 | 252篇 |
2015年 | 195篇 |
2014年 | 335篇 |
2013年 | 622篇 |
2012年 | 501篇 |
2011年 | 703篇 |
2010年 | 492篇 |
2009年 | 447篇 |
2008年 | 511篇 |
2007年 | 465篇 |
2006年 | 387篇 |
2005年 | 354篇 |
2004年 | 278篇 |
2003年 | 277篇 |
2002年 | 244篇 |
2001年 | 126篇 |
2000年 | 119篇 |
1999年 | 135篇 |
1998年 | 210篇 |
1997年 | 154篇 |
1996年 | 116篇 |
1995年 | 111篇 |
1994年 | 108篇 |
1993年 | 84篇 |
1992年 | 78篇 |
1991年 | 37篇 |
1990年 | 43篇 |
1989年 | 55篇 |
1988年 | 51篇 |
1987年 | 54篇 |
1986年 | 41篇 |
1985年 | 69篇 |
1984年 | 54篇 |
1983年 | 52篇 |
1982年 | 47篇 |
1981年 | 32篇 |
1980年 | 34篇 |
1979年 | 25篇 |
1978年 | 30篇 |
1977年 | 32篇 |
1976年 | 36篇 |
1975年 | 20篇 |
1973年 | 19篇 |
排序方式: 共有9401条查询结果,搜索用时 8 毫秒
91.
Sheng Ying Zohar Yoni Ringeissen Christophe Lange Jane Fontaine Pascal Barrett Clark 《Journal of Automated Reasoning》2022,66(3):331-355
Journal of Automated Reasoning - Algebraic datatypes, and among them lists and trees, have attracted a lot of interest in automated reasoning and Satisfiability Modulo Theories (SMT). Since its... 相似文献
92.
Hagedorn Christopher Huegle Johannes Schlosser Rainer 《Journal of Intelligent Manufacturing》2022,33(7):2027-2043
Journal of Intelligent Manufacturing - In discrete manufacturing, the knowledge about causal relationships makes it possible to avoid unforeseen production downtimes by identifying their root... 相似文献
93.
Joan C. Lo Gerald J. Beck George A. Kaysen Christopher T. Chan Alan S. Kliger Michael V. Rocco Glenn M. Chertow for the FHN Study 《Hemodialysis international. International Symposium on Home Hemodialysis》2017,21(2):190-196
Introduction: End‐stage renal disease is associated with elevations in circulating prolactin concentrations, but the association of prolactin concentrations with intermediate health outcomes and the effects of hemodialysis frequency on changes in serum prolactin have not been examined. Methods: The FHN Daily and Nocturnal Dialysis Trials compared the effects of conventional thrice weekly hemodialysis with in‐center daily hemodialysis (6 days/week) and nocturnal home hemodialysis (6 nights/week) over 12 months and obtained measures of health‐related quality of life, self‐reported physical function, mental health and cognition. Serum prolactin concentrations were measured at baseline and 12‐month follow‐up in 70% of the FHN Trial cohort to examine the associations among serum prolactin concentrations and physical, mental and cognitive function and the effects of hemodialysis frequency on serum prolactin. Findings: Among 177 Daily Trial and 60 Nocturnal Trial participants with baseline serum prolactin measurements, the median serum prolactin concentration was 65 ng/mL (25th–75th percentile 48–195 ng/mL) and 81% had serum prolactin concentrations >30 ng/mL. While serum prolactin was associated with sex (higher in women), we observed no association between baseline serum prolactin and age, dialysis vintage, and baseline measures of physical, mental and cognitive function. Furthermore, there was no significant effect of hemodialysis frequency on serum prolactin in either of the two trials. Discussion: Serum prolactin concentrations were elevated in the large majority of patients with ESRD, but were not associated with several measures of health status. Circulating prolactin levels also do not appear to decrease in response to more frequent hemodialysis over a one‐year period. 相似文献
94.
95.
96.
Christopher Garcia 《工程优选》2016,48(9):1515-1528
This work studies a scheduling problem where each job must be either accepted and scheduled to complete within its specified due window, or rejected altogether. Each job has a certain processing time and contributes a certain profit if accepted or penalty cost if rejected. There is a set of renewable resources, and no resource limit can be exceeded at any time. Each job requires a certain amount of each resource when processed, and the objective is to maximize total profit. A mixed-integer programming formulation and three approximation algorithms are presented: a priority rule heuristic, an algorithm based on the metaheuristic for randomized priority search and an evolutionary algorithm. Computational experiments comparing these four solution methods were performed on a set of generated benchmark problems covering a wide range of problem characteristics. The evolutionary algorithm outperformed the other methods in most cases, often significantly, and never significantly underperformed any method. 相似文献
97.
98.
Gian Luigi Angrisani Piriya Taptimthong Susanne Elisabeth Thürer Christian Klose Hans Jürgen Maier Marc Christopher Wurz Kai Möhwald 《Advanced Engineering Materials》2018,20(9)
99.
Tao Jin Christopher D. Easton Hong Yin Malisja de Vries 《Science and Technology of Advanced Materials》2018,19(1):381-395
Nitrogen-doped graphene oxide monoliths (GOMs) were readily constructed by crosslinking graphene oxide (GO) using triethylenetetramine (TETA) and hydroxyethyl cellulose (HEC). The addition of HEC was beneficial to the formation of a network structure compared to that in the absence of HEC. The generated monoliths have shown various morphologies with different d spacing, layer thickness, and micropore size. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses provided evidences for the formation of covalent C–N bonds and some nitrogen-containing heterocyclic composition inside the graphene oxide sheet, indicating that the interaction of GO with the amine crosslinker involved the crosslinking reaction between GO epoxides and amine groups. HEC was also involved in the N-doping reaction via the partial reduction of oxygen in HEC molecules. Analysis of X-ray diffraction (XRD) results indicated that the lattice distance between GO sheets increased after TETA/HEC crosslinking. Thermogravimetric analysis (TGA) confirmed the successful incorporation of crosslinker moieties on the surface of GO sheets. The fabricated GOMs could be used to efficiently adsorb metal ions and arsenate by the introduced polar functional groups on GO sheets and porous structures based on hydrogen bonds, whose morphologies and compositions were confirmed via XRD, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). 相似文献
100.
Barrett CP Blair P Buller GS Neilson DT Robertson B Smith EC Taghizadeh MR Walker AC 《Applied optics》1996,35(35):6934-6944
We describe an optical system developed to form the basis of a 64 × 64 free-space optical matrix-matrix crossbar switch. The design and performance of each of the main optical components is discussed: lenses, diffractive optical elements, and polarizing beamsplitters, together with the optomechanical hardware design. For these components, throughput levels of -6.9 dB have been achieved, which is compatible with full system operation at 10(-12) bit error rates at ≥270 Mbits s(-1). 相似文献