全文获取类型
收费全文 | 19670篇 |
免费 | 1556篇 |
国内免费 | 492篇 |
专业分类
电工技术 | 620篇 |
综合类 | 1050篇 |
化学工业 | 9258篇 |
金属工艺 | 243篇 |
机械仪表 | 331篇 |
建筑科学 | 1346篇 |
矿业工程 | 149篇 |
能源动力 | 2651篇 |
轻工业 | 1664篇 |
水利工程 | 161篇 |
石油天然气 | 488篇 |
武器工业 | 19篇 |
无线电 | 332篇 |
一般工业技术 | 2648篇 |
冶金工业 | 314篇 |
原子能技术 | 123篇 |
自动化技术 | 321篇 |
出版年
2024年 | 76篇 |
2023年 | 356篇 |
2022年 | 681篇 |
2021年 | 824篇 |
2020年 | 737篇 |
2019年 | 655篇 |
2018年 | 447篇 |
2017年 | 585篇 |
2016年 | 516篇 |
2015年 | 525篇 |
2014年 | 1022篇 |
2013年 | 1013篇 |
2012年 | 1516篇 |
2011年 | 1478篇 |
2010年 | 1214篇 |
2009年 | 1113篇 |
2008年 | 962篇 |
2007年 | 1259篇 |
2006年 | 1031篇 |
2005年 | 950篇 |
2004年 | 813篇 |
2003年 | 740篇 |
2002年 | 537篇 |
2001年 | 455篇 |
2000年 | 426篇 |
1999年 | 374篇 |
1998年 | 300篇 |
1997年 | 236篇 |
1996年 | 186篇 |
1995年 | 128篇 |
1994年 | 140篇 |
1993年 | 122篇 |
1992年 | 90篇 |
1991年 | 62篇 |
1990年 | 37篇 |
1989年 | 16篇 |
1988年 | 22篇 |
1987年 | 12篇 |
1986年 | 13篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1951年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Addition of Tween 80 to the growth medium of baker's yeast (Saccharomyces cerevisiae) under anaerobic conditions resulted in an increased content of 9-cis-octadecenoic acid (oleic acid) in a membrane preparation consisting mainly of plasma membrane. There was no significant effect on the pyruvate decarboxylation capacity of disintegrated cells, but that of intact cells was significantly enhanced, presumably because of an oleate-induced increase in the permeability of the plasma membrane to pyruvate. 相似文献
103.
KEITH A. SCHIMMEL ALIEU WURIE SHAMSUDDIN ILIAS JAN E. PEGRAM 《Journal of food science》1996,61(3):577-580
We tested the feasibility of using polymer membranes for a self-hydrating packaging system to reconstitute freeze-dried foods using nonpurified water. Several commercial membranes were screened according to (1) hydration rate, (2) water permeability, (3) passage of microorganisms, (4) salt rejection, and (5) strength. The most promising membranes were used for developing and testing prototype packaging systems. A feasible self-contained rehydration system was a nylon-6 polyamide membrane that rehydrated the freeze-dried food within 30 min while passage of microorganisms was prevented. The temperature was 37°C, and the food contained 0.5g/5g of a low molecular weight solute (salt). Such self-contained membrane rehydration systems must be designed to accommodate expected environmental conditions such as temperature, relative humidity, and nature of the product. 相似文献
104.
Porous Materials: Submicrometer‐Sized ZIF‐71 Filled Organophilic Membranes for Improved Bioethanol Recovery: Mechanistic Insights by Monte Carlo Simulation and FTIR Spectroscopy (Adv. Funct. Mater. 4/2015) 下载免费PDF全文
105.
Sahng Hyuck Woo Nak Jun Lee Seung Ho Yook Hee Soo Kim Jieun Choi Jae-Hun Kim So Young Lee Jong Hyun Jang Sung Jong Yoo Young-Gi Yoon Jonghee Han Hyoung-Juhn Kim 《Advanced functional materials》2023,33(46):2305231
Although extensive research has been conducted, understanding the exact phenomena occurring during the operation of polymer electrolyte fuel cells (PEFCs) remains difficult. This research attempted to identify new reasons for the reduced performance of PEFC using an imaging technique. To begin with, H+ and OH− indicator sensors, which display red, blue, and green values (RGB) using digital microscopes, are developed and attached to each electrode of a membrane electrode assembly to enable quantitative analysis of ion generation. The proposed reaction in the fuel cell can be confirmed, and various reactions occurring in the electrode can be examined using this approach. In particular, H+ is generated at the anode and cathode of the anion exchange membrane fuel cell, which is found to be a major cause of performance deterioration. 相似文献
106.
The electrochemical characteristics of the plasma membranes of single cells and organelles were investigated. Silicon fabrication technology was used to produce a metal ultra-microelectrode (UME). Furthermore, the UME was characterized in a cell medium using electrochemical impedance spectroscopy (EIS). A single rat fibroblast cell, or chloroplast purified from Peperomia metallica leaves, was immobilized by a micropipette after which the UME was inserted into its cytosolic space through cell membrane using a piezo actuator. An in vivo EIS measurement between the UME and the counter electrode outside of a single cell was taken. The measurements were analyzed using equivalent circuits in order to estimate the membrane impedance of a single cell. 相似文献
107.
Hun Soo Jang Seonggwang Yoo Seong Hyeon Kang Jongjun Park Gi‐Gwan Kim Heung Cho Ko 《Advanced functional materials》2020,30(5)
This work demonstrates a means of automatic transformation from planar electronic devices to desirable 3D forms. The method uses a spatially designed thermoplastic framework created via extrusion shear printing of acrylonitrile–butadiene–styrene (ABS) on a stress‐free ABS film, which can be laminated to a membrane‐type electronic device layer. Thermal annealing above the glass transition temperature allows stress relaxation in the printed polymer chains, resulting in an overall shape transformation of the framework. In addition, the significant reduction in the Young's modulus and the ability of the polymer chains to reflow in the rubbery state release the stress concentration in the electronic device layer, which can be positioned outside the neutral mechanical plane. Electrical analyses and mechanical simulations of a membrane‐type Au electrode and indium gallium zinc oxide transistor arrays before and after transformation confirm the versatility of this method for developing 3D electronic devices based on planar forms. 相似文献
108.
针对目前高质量的滤色膜制造工艺复杂,成本较高的问题,提出了一种利用LED做背光源结合一种时间混色的液晶显示技术,实现颜色显示无滤膜化,使液晶显示系统具有结构简单、色彩输出能力强、性能价格比高的优点。 相似文献
109.
为提高社区检测算法的速度和质量,提出一种基于膜计算的检测算法.利用膜计算的分布性、并行性,来提高检测的速度和质量,膜对象进化时使用标签传播、遗传规则,实现社区检测的并行计算,并进行仿真实验.结果表明:该算法快速、准确,具有可行性,为网络的社区检测提供了一种新思路. 相似文献
110.
Known Good Die 总被引:1,自引:0,他引:1
Larry Gilg 《Journal of Electronic Testing》1997,10(1-2):15-25
Advances in reducing size and increasing functionality of electronics have been due primarily to the shrinking geometries and increasing performance of integrated circuit technologies. Recently, development efforts aimed at reducing size and increasingfunctionality have focused on the first level of the electronicpackage. The result has been the development of multichip packaging,technologies in which bare IC chips are mounted on a single high density substrate that serves to package thechips, as well as interconnect them. A number of benefits accruebecause of multichip packaging, namely, increased chip density,space savings, higher performance, and less weight. Therefore, thesetechnologies are attractive for today's light weight, portable, highperformance electronic equipment and devices.In spite of these benefits, multichip packaging has not shown the kind of explosive growth and expansion that was predicted[1]. A major inhibitor for these technologies has been theavailability of fully tested and conditioned bare die, orknown good die. This paper reviews the issues and technologies associated with test and burn-in of bareor minimally packaged IC products. 相似文献