全文获取类型
收费全文 | 3977篇 |
免费 | 70篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 53篇 |
综合类 | 1篇 |
化学工业 | 538篇 |
金属工艺 | 41篇 |
机械仪表 | 78篇 |
建筑科学 | 163篇 |
矿业工程 | 23篇 |
能源动力 | 86篇 |
轻工业 | 307篇 |
水利工程 | 28篇 |
石油天然气 | 11篇 |
武器工业 | 1篇 |
无线电 | 349篇 |
一般工业技术 | 502篇 |
冶金工业 | 1195篇 |
原子能技术 | 45篇 |
自动化技术 | 632篇 |
出版年
2022年 | 45篇 |
2021年 | 88篇 |
2020年 | 28篇 |
2019年 | 48篇 |
2018年 | 65篇 |
2017年 | 49篇 |
2016年 | 58篇 |
2015年 | 36篇 |
2014年 | 91篇 |
2013年 | 189篇 |
2012年 | 124篇 |
2011年 | 197篇 |
2010年 | 140篇 |
2009年 | 149篇 |
2008年 | 157篇 |
2007年 | 151篇 |
2006年 | 113篇 |
2005年 | 129篇 |
2004年 | 108篇 |
2003年 | 106篇 |
2002年 | 94篇 |
2001年 | 83篇 |
2000年 | 62篇 |
1999年 | 74篇 |
1998年 | 350篇 |
1997年 | 223篇 |
1996年 | 126篇 |
1995年 | 91篇 |
1994年 | 89篇 |
1993年 | 93篇 |
1992年 | 49篇 |
1991年 | 29篇 |
1990年 | 37篇 |
1989年 | 41篇 |
1988年 | 37篇 |
1987年 | 30篇 |
1986年 | 38篇 |
1985年 | 47篇 |
1984年 | 46篇 |
1983年 | 27篇 |
1982年 | 35篇 |
1981年 | 31篇 |
1980年 | 23篇 |
1979年 | 25篇 |
1978年 | 17篇 |
1977年 | 30篇 |
1976年 | 21篇 |
1974年 | 15篇 |
1973年 | 15篇 |
1972年 | 16篇 |
排序方式: 共有4053条查询结果,搜索用时 31 毫秒
1.
Stefanie Vanbecelaere Katrien Van den Berghe Frederik Cornillie Delphine Sasanguie Bert Reynvoet Fien Depaepe 《Journal of Computer Assisted Learning》2020,36(4):502-513
For the training of academic skills, digital educational games with integrated adaptivity are promising. Adaptive games are considered superior to non-adaptive games, because they constantly assess children's performance, and accordingly adapt the difficulty of the tasks corresponding to the children's individual level. However, empirical evidence with regard to the effectivity of adaptive compared to non-adaptive games is limited. A study was conducted with 191 children from the third year of Kinder garten who were enrolled in one of three conditions, that is, playing an adaptive version of the reading game (RG), a non-adaptive version of the RG or training with pen-and-paper exercises. In all three conditions, children trained emergent reading (phonological awareness and letter knowledge) once a week for 30 min over a period of 5 weeks. Children's performance on cognitive (phonological awareness, letter knowledge, reading fluency) and non-cognitive (motivation, self-concept) factors was assessed. Results revealed a significant improvement in phonological awareness and letter knowledge in all conditions. However, no differences between the conditions were observed with respect to children's improvement on phonological awareness and letter knowledge or on their post-test scores for reading fluency. With regard to motivation and self-concept, again, no differences in these non-cognitive factors were observed across conditions. 相似文献
2.
Bengü Ergüden 《Yeast (Chichester, England)》2019,36(2):99-105
The correct separation of chromosomes during mitosis is necessary to prevent genetic instability and aneuploidy, which are responsible for cancer and other diseases, and it depends on proper centrosome duplication. In a recent study, we found that Smy2 can suppress the essential role of Mps2 in the insertion of yeast centrosome into the nuclear membrane by interacting with Eap1, Scp160, and Asc1 and designated this network as SESA (S my2, E ap1, S cp160, A sc1). Detailed analysis showed that the SESA network is part of a mechanism which regulates translation of POM34 mRNA. Thus, SESA is a system that suppresses spindle pole body duplication defects by repressing the translation of POM34 mRNA. In this study, we performed a genome-wide screening in order to identify new members of the SESA network and confirmed Dhh1 as a putative member. Dhh1 is a cytoplasmic DEAD-box helicase known to regulate translation. Therefore, we hypothesized that Dhh1 is responsible for the highly selective inhibition of POM34 mRNA by SESA. 相似文献
3.
The solvent-dependent polymorphism of the active pharmaceutical ingredient (API) carbamazepine is interpreted from calculations of the solid-state and API-solvent intermolecular interactions. These simulations suggested that apolar solute-solute interactions could be disrupted by apolar solvents. In contrast, the polar solute-solute interactions were found to be easily disrupted by polar and protic solvents. This is consistent with experimental observations that the crystallization of the metastable form II is more dominant in apolar solvents. The Mercury program remains the gold standard in terms of usability; however, further expansion into more complex simulation techniques could make this package of even greater use in pharmaceutical manufacturing workflows. 相似文献
4.
We demonstrate that alkali-halide salts, particularly potassium bromide, can reduce the photothermal emission (PTE) from single walled carbon nanotubes (SWNT). PTE is a prominent spectral feature in Raman spectroscopy when a near infrared laser is used to analyze a dark colored sample. We subsequently show that trapping salts inside SWNT and coating SWNT with the salt has a more pronounced impact on not only reducing PTE, but also enhancing the intensity of the Raman spectral features. The effect, which we have called nanotube enhanced Raman spectroscopy (NERS), has differences and similarities to the widely studied surface enhanced Raman spectroscopy (SERS). 相似文献
5.
6.
Poly(vinyl alcohol) is crosslinked in dilute solution (c=0.1 wt%) with glutaraldehyde. The reaction product is characterized by viscometry and gel permeation chromatography (g.p.c.). The intrinsic viscosity decreases with increasing degree of crosslinking and does not depend on temperature. G.p.c. reveals that the reaction product is not homogeneous, but consists of a mixture of particles with different sizes, possibly both intra- and intermolecularly crosslinked molecules. The intramolecularly crosslinked molecules are smaller in size than the initial polymer molecules and their size depends on the degree of crosslinking. They possess a narrow particle size distribution even if the initial polymer sample had a broad molecular weight distribution. 相似文献
7.
In response to an interpretation made by Moore and Akgerman of data taken from a recent publication, previously unexplainable phenomena are accounted for, based on new experimental results. These relate to a thermodynamic equilibrium reaction involving saturation of aromatic hydrocarbons in synthetic crude middle distillates. 相似文献
8.
An extended model and calculus, called RasterCalc, is presented for operations on discrete graphics rasters, including their colour functions. The operations are separated into two main categories: operations on domains, and operations on colour functions. The operations are further classified as local and remote, depending on the correspondence between destination and source pixels. The new raster element or pixel can be a function of a single element from one or more rasters, a function of a small area from other rasters, or a function of entire rasters. Local operations have their main applications in computer graphics, while remote operations are more oriented towards image processing. A mathematically oriented notation is used to define and represent the operations included. RasterCalc has been implemented as a procedure package in Pascal, to be used on a powerful, yet expensive display. Recently a C version has been completed for a personal colour computer with a special chip for raster operations. The work reported in this paper is partially supplied by the Dutch Technical Sciences Foundation, under project number LWI 14.0130: “Facilities for raster graphics in programming languages” 相似文献
9.
Ronald R. Delyser Sheila S. Thompson Jerry Edelstein Corinne Lengsfeld Albert J. Rosa Paul J. Rullkoetter Robert Whitman Margaret Whitt 《工程教育杂志》2003,92(3):269-273
A team of faculty members at the University of Denver changed the learning environment in key courses in the Department of Engineering from predominately teacher centered to student centered. Through this funded project new grading methods were implemented, classrooms were renovated and wired with studio layouts to facilitate learning, the Engineering Circuits Laboratory was rewired and instrumented for automated data acquisition and reporting, and two new pedagogical approaches were developed. At the onset of the project, six goals were established related to student learning. The introduction of industry standard hardware and software provided students with unprecedented hands‐on experience and project related activities stimulated faculty innovations in other current and future courses. Assessment results indicate that the new grading system improved the clarity of expectations for students before assignments were given resulting in increased reported motivation for learning in many courses. Even though course GPAs did not always reflect higher achievement on graded work, faculty members firmly believe that deeper understanding was achieved because more complex material was assimilated. 相似文献
10.
A short-pulse 1.444-μm laser based on Nd:YAG technology has been demonstrated. The 1.444-μm is eye-safe. With the cavity-dump technique, a pulse of 50 m× and 14 ns was obtained. The beam quality was excellent with an M2 of 1.6 by the use of a telescopic resonator. Silicon-window polarizers were used to suppress the 1.06-μm radiation but showed 1.444-μm absorption as well 相似文献