全文获取类型
收费全文 | 939319篇 |
免费 | 65663篇 |
国内免费 | 45459篇 |
专业分类
电工技术 | 54595篇 |
综合类 | 58738篇 |
化学工业 | 124756篇 |
金属工艺 | 53912篇 |
机械仪表 | 49748篇 |
建筑科学 | 49778篇 |
矿业工程 | 25512篇 |
能源动力 | 24182篇 |
轻工业 | 93438篇 |
水利工程 | 22567篇 |
石油天然气 | 26272篇 |
武器工业 | 8788篇 |
无线电 | 103100篇 |
一般工业技术 | 124535篇 |
冶金工业 | 99313篇 |
原子能技术 | 19059篇 |
自动化技术 | 112148篇 |
出版年
2023年 | 9143篇 |
2022年 | 22372篇 |
2021年 | 29125篇 |
2020年 | 21239篇 |
2019年 | 16004篇 |
2018年 | 19045篇 |
2017年 | 21673篇 |
2016年 | 20159篇 |
2015年 | 26997篇 |
2014年 | 35922篇 |
2013年 | 52552篇 |
2012年 | 54264篇 |
2011年 | 60214篇 |
2010年 | 55231篇 |
2009年 | 54974篇 |
2008年 | 56794篇 |
2007年 | 55944篇 |
2006年 | 47503篇 |
2005年 | 40125篇 |
2004年 | 31781篇 |
2003年 | 23874篇 |
2002年 | 22688篇 |
2001年 | 21685篇 |
2000年 | 18603篇 |
1999年 | 13150篇 |
1998年 | 25349篇 |
1997年 | 18074篇 |
1996年 | 13970篇 |
1995年 | 10746篇 |
1994年 | 9246篇 |
1993年 | 9285篇 |
1992年 | 6819篇 |
1991年 | 6461篇 |
1990年 | 6256篇 |
1989年 | 6310篇 |
1988年 | 5866篇 |
1987年 | 5226篇 |
1986年 | 5187篇 |
1985年 | 5788篇 |
1984年 | 5346篇 |
1983年 | 4964篇 |
1982年 | 4619篇 |
1981年 | 4761篇 |
1980年 | 4730篇 |
1979年 | 4464篇 |
1978年 | 4353篇 |
1977年 | 4906篇 |
1976年 | 6434篇 |
1975年 | 3721篇 |
1973年 | 3748篇 |
排序方式: 共有10000条查询结果,搜索用时 2 毫秒
11.
At some point in their careers, clinicians who work or consult in forensic and correctional settings will almost certainly encounter individuals who exhibit psychopathic personality features. Because of the widespread use of this disorder to inform legal and clinical decision making, psychologists should be exceedingly familiar with the relevant research literature on this topic before venturing into these settings. This article reviews the empirical bases of several clinically relevant claims and assertions regarding psychopathy and concludes that many areas of research are decidedly more equivocal in their findings than is commonly perceived. Although there is much to be gained by assessing psychopathy in various contexts, clinicians need to be cautious about drawing overzealous and empirically questionable conclusions about an important disorder that also has great potential for abuse. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
12.
The application of barrier discharges at atmospheric pressure in air expands on the market of plasma technology, because it is an ecological and cost‐effective alternative to other processes of surface treatment. These plasmas usually consist of a multitude of spatially and temporally localized filaments, whose distribution should be as even as possible for homogeneous treatment. This holds especially for the plasma treatment of sensitive goods such as wool or other textiles. In equipment for continuous pass of material the barrier arrangements often consist of a system cylinder – cylinder or cylinder – plane, whereby the gap width changes locally. Space distribution and intensity of filaments has been investigated by means of short‐time photography and spatially resolved measurement of current distribution and energy distribution derived from it. The local dependency found can be explained by means of a capacitive equivalent circuit. 相似文献
13.
14.
Ciofi C. Crupi F. Pace C. Scandurra G. 《IEEE transactions on instrumentation and measurement》2003,52(5):1533-1536
Low-frequency noise measurements represent an interesting investigation technique for the characterization of the quality and reliability of microelectronic materials and devices. Performing meaningful noise measurements at low and very low (f<1 Hz) frequencies, however, may be quite challenging, particularly because of the many sources of interference that superimpose on the noise signal. For this reason, packaged samples are preferred because they allow accurate shielding from the external environment, and because keeping the sample in close proximity to the low-noise biasing system and amplifier reduces microphonic and electromagnetic disturbances. Notwithstanding this, the possibility of performing low-frequency noise measurements at wafer level would be quite interesting, both because of the ease of obtaining wafer-level samples from industries with respect to packaged samples, and because this would avoid possible packaging-process induced device degradation. The purpose of this work is to demonstrate that it is, in fact, possible to design and build a dedicated probe system for performing high-sensitivity, low-frequency noise measurements on metal-oxide-semiconductor devices at wafer level. 相似文献
15.
B. Pantchev P. Danesh K. Antonova B. Schmidt D. Grambole J. Baran 《Journal of Materials Science: Materials in Electronics》2003,14(10-12):751-752
The hydrogen content, its depth distribution, and its bonding configuration have been studied in hydrogenated amorphous silicon prepared by plasma-enhanced chemical vapor deposition with hydrogen-diluted silane. Nuclear reaction analysis and infrared spectroscopy were used to determine the total amount of hydrogen and its bonded component, respectively. It has been established that the total concentration of hydrogen does not depend on the film thickness, and has a uniform depth profile. The concentration of bonded hydrogen changes with the film thickness within the measurement accuracy. The data obtained suggest the presence of molecular (non-bonded) hydrogen, uniformly distributed in concentration across the film thickness. 相似文献
16.
V. N. Tsygankov V. V. Safonov A. I. Kozlov V. P. Gavrilov 《Inorganic Materials》2003,39(10):1076-1078
The GeO2–NiO system is studied in the stability range of Ni2GeO4 by temperature-dependent resistivity measurements, in combination with x-ray diffraction, differential thermal analysis, and thermogravimetry. The resistivity of the starting mixtures and heat-treated samples is measured in the composition range 55–90 mol % NiO. The effect of air humidity on the resistivity of the samples is examined. 相似文献
17.
A cell vertex finite volume method for the solution of steady compressible turbulent flow problems on unstructured hybrid
meshes of tetrahedra, prisms, pyramids and hexahedra is described. These hybrid meshes are constructed by firstly discretising
the computational domain using tetrahedral elements and then by merging certain tetrahedra. A one equation turbulence model
is employed and the solution of the steady flow equations is obtained by explicit relaxation. The solution process is accelerated
by the addition of a multigrid method, in which the coarse meshes are generated by agglomeration, and by parallelisation.
The approach is shown to be effective for the simulation of a number of 3D flows of current practical interest.
Sponsored by The Research Council of Norway, project number 125676/410
Dedicated to the memory of Prof. Mike Crisfield, a respected colleague 相似文献
18.
Two types of photo heterojunction bipolar transistor (HBT) to directly down-convert optical signals to electronic signals have been reported in the literature: a conventional photo-HBT in which light penetrates through the area of the base-collector junction and an HBT where light shines through the base-collector edge for higher conversion efficiency. Although the performance in relation to bias conditions has been published, the detailed analyses for identifying the parameters and bias conditions that provide optimum direct down-conversion have not been examined. This paper provides a full explanation of the operation of the down-conversion for both HBT configurations based on low-frequency analyses. Such information is useful for both understanding the nonlinear mechanisms involved and designing for maximum efficiency. In addition, a new circuit has been developed from the basic HBT down-conversion circuit that provides improved performance. 相似文献
19.
Thomy V. Dubois L. Vanoverschelde C. Sozanski J.P. Pribetich J. 《IEEE sensors journal》2004,4(6):772-778
This paper describes a novel planar antenna sensor created for the purpose of noninvasive temperature measurements using microwave radiometry. In order to improve radiometric measurements in industrial applications, a new generation of sensors is introduced, composed of a metallic sheet. Simulations based upon the method of moments is used both to design and to determine their electromagnetic performances. This paper also describes a radiometric device using these sensors to measure and control the temperature of food products during deep freezing processes. The results and discussions are presented. 相似文献
20.