全文获取类型
收费全文 | 1392篇 |
免费 | 81篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 7篇 |
综合类 | 2篇 |
化学工业 | 323篇 |
金属工艺 | 58篇 |
机械仪表 | 68篇 |
建筑科学 | 17篇 |
能源动力 | 68篇 |
轻工业 | 149篇 |
水利工程 | 3篇 |
石油天然气 | 2篇 |
无线电 | 197篇 |
一般工业技术 | 331篇 |
冶金工业 | 74篇 |
原子能技术 | 5篇 |
自动化技术 | 171篇 |
出版年
2024年 | 3篇 |
2023年 | 18篇 |
2022年 | 26篇 |
2021年 | 46篇 |
2020年 | 34篇 |
2019年 | 29篇 |
2018年 | 37篇 |
2017年 | 46篇 |
2016年 | 41篇 |
2015年 | 39篇 |
2014年 | 68篇 |
2013年 | 80篇 |
2012年 | 79篇 |
2011年 | 124篇 |
2010年 | 93篇 |
2009年 | 87篇 |
2008年 | 82篇 |
2007年 | 69篇 |
2006年 | 52篇 |
2005年 | 53篇 |
2004年 | 48篇 |
2003年 | 56篇 |
2002年 | 37篇 |
2001年 | 38篇 |
2000年 | 20篇 |
1999年 | 25篇 |
1998年 | 28篇 |
1997年 | 21篇 |
1996年 | 15篇 |
1995年 | 19篇 |
1994年 | 12篇 |
1993年 | 12篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有1475条查询结果,搜索用时 15 毫秒
71.
The main purpose of this study is to find out the best solution of the vehicle routing problem simultaneously considering heterogeneous vehicles, double trips, and multiple depots by using a hybrid genetic algorithm. This study suggested a mathematical programming model with a new numerical formula which presents the amount of delivery and sub-tour elimination. This model gives an optimal solution by using OPL-STUDIO(ILOG CPLEX). This study also suggests a hybrid genetic algorithm (HGA) which considers the improvement of generation for an initial solution, three different heuristic processes, and a float mutation rate for escaping from the local solution in order to find the best solution. The suggested HGA is also compared with the results of a general genetic algorithm and existing problems suggested by Eilon and Fisher. We found better solutions rather than the existing genetic algorithms. 相似文献
72.
We present a continuous feedback stabilizer for nonlinear systems in the strict-feedback form, whose chained integrator part has the power of positive odd rational numbers. Since the power is not restricted to be larger than or equal to one, the linearization of the system at the origin may fail. Nevertheless, we show that the closed loop system is globally asymptotically stable (GAS) with the proposed continuous (but, possibly not differentiable) feedback. We formulate a condition that enables our design by characterizing the powers of the given system. The condition also shows that our result is an extension of Qian and Lin [Non-lipschitz continuous stabilizers for nonlinear systems with uncontrollable unstable linearization, Systems Control Lett. 42 (2001) 185–200] where the power of odd positive integers has been considered. New result on the global finite time stabilization problem is also presented. 相似文献
73.
H. Shim C.-M. Kyung 《Electronics letters》2007,43(7):382-383
A data reuse algorithm for multiple reference frame motion estimation is described. The proposed algorithm reduces memory access by modifying the reference frame search order and search centre such that the likelihood of data reuse is increased. Experimental results show that the algorithm reduces memory access by 15-30% compared to the conventional fast reference frame selection algorithm, while maintaining similar bit rate and PSNR 相似文献
74.
This work presents a low‐voltage static random access memory (SRAM) technique based on a dual‐boosted cell array. For each read/write cycle, the wordline and cell power node of selected SRAM cells are boosted into two different voltage levels. This technique enhances the read static noise margin to a sufficient level without an increase in cell size. It also improves the SRAM circuit speed due to an increase in the cell read‐out current. A 0.18 µm CMOS 256‐kbit SRAM macro is fabricated with the proposed technique, which demonstrates 0.8 V operation with 50 MHz while consuming 65 µW/MHz. It also demonstrates an 87% bit error rate reduction while operating with a 43% higher clock frequency compared with that of conventional SRAM. 相似文献
75.
This study examines the radio frequency identification (RFID) adoption decision process and proposes a model predicting the likelihood of adopting RFID within organizations in the healthcare industry. A considerable number of studies have been conducted regarding organizational information technology (IT) adoption, but the nature of the organizational IT adoption process is still not well understood. Especially, although there are a number of variables and categories that have been found empirically to be related to adoption behavior, there is little in the way of evidence to suggest the origin or motivation behind the adoption. Thus, this study investigates the underlying motivations and driving forces behind the adoption of RFID using the theory of technology-push and need-pull. In this study, an organizational RFID adoption model is proposed and empirically tested by a survey using a sample of 126 senior executives in U.S. hospitals. The model posits that three categories of factors, technology push, need pull, and presence of champions, determine the likelihood of adopting RFID within organizations. This study also found that the relationships between those three categories and the likelihood of adopting RFID are strengthened or weakened by organizational readiness. 相似文献
76.
Microfluidic Synthesis of pH‐Sensitive Multicompartmental Microparticles for Multimodulated Drug Release 下载免费PDF全文
Hyeon Ung Kim Dae Gun Choi Yoon Ho Roh Min Suk Shim Ki Wan Bong 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(25):3463-3470
Stimuli‐responsive carriers releasing multiple drugs have been researched for synergistic combinatorial cancer treatment with reduced side‐effects. However, previously used drug carriers have limitations in encapsulating multiple drug components in a single carrier and releasing each drug independently. In this work, pH‐sensitive, multimodulated, anisotropic drug carrier particles are synthesized using an acid‐cleavable polymer and stop‐flow lithography. The particles exhibit a faster drug release rate at the acidic pH of tumors than at physiological pH, demonstrating their potential for tumor‐selective drug release. The drug release rate of the particles can be adjusted by controlling the monomer composition. To accomplish multimodulated drug release, multicompartmental particles are synthesized. The drug release profile of each compartment is programmed by tailoring the monomer composition. These pH‐sensitive, multicompartmental particles are promising drug carriers enabling tumor‐selective and multimodulated release of multiple drugs for synergistic combination cancer therapy. 相似文献
77.
Short communication: lack of stage-specific embryonic antigen-1 expression by bovine embryos and primordial germ cells 总被引:1,自引:0,他引:1
The objective of this study was to determine whether stage-specific embryonic antigen-1, a cellular marker commonly used to identify murine undifferentiated embryonic cells, is also a useful marker for bovine pluripotent cells. Expression of stage-specific embryonic antigen-1 was examined by indirect immunohistochemistry on bovine preimplantation embryos and on primordial germ cells contained in the genital ridge. Expression of stage-specific embryonic antigen-1 was not observed in any of the cleavage-stage bovine embryos examined, including one-cell, two-cell, four-cell, eight-cell, morula, and blastocyst stages, nor in tissue sections of bovine genital ridges collected from embryos on d 34, 37, and 40 of gestation. As expected, expression of stage-specific embryonic antigen-1 was detected on murine preimplantation embryos and on murine teratocarcinoma cells. Results of this study indicate that, unlike in the mouse, stage-specific embryonic antigen-1 is not a useful cellular marker for pluripotent bovine embryonic cells or bovine primordial germ cells. 相似文献
78.
Summary A series of polyblends of poly(1,4-phenylene vinylene), PPV, and poly(2,5-dimethoxy-1,4-phenylene vinylene), PDMPV, were prepared in film form from precursor polyblends of the respective sulfonium salt polymers, which were separately prepared from the respectivebis(sulfonium salt) monomers. The blend films were doped with I2 at room temperature to obtain a wide range of electrical conductivities (10–2 to 102Scm–1) depending on the blend composition. The higher the content of PDMPV in the blends the higher was the conductivity. 相似文献
79.
Polypropylene (PP)/montmorillonite (MMT) nanocomposites were prepared by compounding maleic anhydride‐g‐polypropylene (MAPP) with MMT modified with α,ω‐diaminododecane. Structural characterization confirmed the formation of characteristic amide linkages and the intercalation of MAPP between the silicate layers. In particular, X‐ray diffraction patterns of the modified clay and MAPP/MMT composites showed 001 basal spacing enlargement as much as 1.49 nm. Thermogravimetric analysis revealed that the thermal decomposition of the composite took place at a slightly higher temperature than that of MAPP. The heat of fusion of the MAPP phase decreased, indicating that the crystallization of MAPP was suppressed by the clay layers. PP/MAPP/MMT composites showed a 20–35% higher tensile modulus and tensile strength compared to those corresponding to PP/MAPP. However, the elongation at break decreased drastically, even when the content of MMT was as low as 1.25–5 wt %. The relatively short chain length and loop structure of MAPP bound to the clay layers made the penetration of MAPP molecules into the PP homopolymer phase implausible and is thought to be responsible for the decreased elongation at break. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 307–311, 2005 相似文献
80.
Individual digit-tip forces and moments during torque production on a mechanically fixed circular object were studied. During the experiments, subjects positioned each digit on a 6-dimensional force/moment sensor attached to a circular handle and produced a maximum voluntary torque on the handle. The torque direction and the orientation of the torque axis were varied. From this study, it is concluded that: (1) the maximum torque in the closing (clockwise) direction was larger than in the opening (counter clockwise) direction; (2) the thumb and little finger had the largest and the smallest share of both total normal force and total moment, respectively; (3) the sharing of total moment between individual digits was not affected by the orientation of the torque axis or by the torque direction, while the sharing of total normal force between the individual digit varied with torque direction; (4) the normal force safety margins were largest and smallest in the thumb and little finger, respectively. 相似文献