全文获取类型
收费全文 | 3329篇 |
免费 | 96篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 54篇 |
综合类 | 2篇 |
化学工业 | 626篇 |
金属工艺 | 73篇 |
机械仪表 | 49篇 |
建筑科学 | 118篇 |
矿业工程 | 21篇 |
能源动力 | 76篇 |
轻工业 | 299篇 |
水利工程 | 23篇 |
石油天然气 | 2篇 |
无线电 | 389篇 |
一般工业技术 | 510篇 |
冶金工业 | 851篇 |
原子能技术 | 57篇 |
自动化技术 | 277篇 |
出版年
2023年 | 23篇 |
2022年 | 28篇 |
2021年 | 46篇 |
2020年 | 32篇 |
2019年 | 42篇 |
2018年 | 42篇 |
2017年 | 44篇 |
2016年 | 56篇 |
2015年 | 60篇 |
2014年 | 60篇 |
2013年 | 124篇 |
2012年 | 94篇 |
2011年 | 143篇 |
2010年 | 85篇 |
2009年 | 112篇 |
2008年 | 131篇 |
2007年 | 82篇 |
2006年 | 87篇 |
2005年 | 67篇 |
2004年 | 66篇 |
2003年 | 75篇 |
2002年 | 84篇 |
2001年 | 69篇 |
2000年 | 64篇 |
1999年 | 76篇 |
1998年 | 266篇 |
1997年 | 183篇 |
1996年 | 120篇 |
1995年 | 95篇 |
1994年 | 90篇 |
1993年 | 86篇 |
1992年 | 52篇 |
1991年 | 73篇 |
1990年 | 47篇 |
1989年 | 46篇 |
1988年 | 45篇 |
1987年 | 37篇 |
1986年 | 27篇 |
1985年 | 46篇 |
1984年 | 40篇 |
1983年 | 34篇 |
1982年 | 20篇 |
1981年 | 23篇 |
1980年 | 24篇 |
1979年 | 19篇 |
1977年 | 28篇 |
1976年 | 57篇 |
1975年 | 19篇 |
1972年 | 18篇 |
1971年 | 17篇 |
排序方式: 共有3427条查询结果,搜索用时 15 毫秒
1.
2.
The multipurpose mask set described, which consists of three stepper reticles, contains 95% of all test structures required for CMOS process development and random defect detection, thereby dramatically reducing the stepper reticle inventory and the frequency of reticle changes. Realizing the mask set by two dozen standard unit processes minimizes the feedback loop for defect density data, parametric data and unit process data 相似文献
3.
C Wilken W Baltes I Mehlitz R Tiebach R Weber 《Zeitschrift für Lebensmittel-Untersuchung und -Forschung》1985,180(6):496-497
A rapid procedure for the isolation and clean-up on a silica gel column is described for the determination of Ochratoxin A from pork kidneys. The detection limit is 0.3 microgram/kg. 相似文献
4.
Carbon based multilayer systems for highly loaded forming tools Amorphous hydrogenated carbon (metal‐free a‐C:H and metal‐containing a‐C:H:Me) films respond very sensitively to local overloads. For example during forming tool operations, hard abrasive particles and locally high stresses on the coating surface can cause crack initiation and early coating failure. Compared to the high hardness, wear resistance and excellent friction properties, in many cases the adhesion of a‐C:H films is relatively insufficient. Adhesion and overload resistance of a‐C:H and a‐C:H:Me, prepared by reactive sputtering, can be influenced in a wide range by different interlayer systems. In the present report the wear mechanism of amorphous carbon coatings and the influence of different metallic, metal nitride and metal carbide interlayers on the growth structure, the adhesion and the load resistance will be reported. Two well adapted multi‐coating systems, successfully tested for highly loaded tools and components, will be presented. 相似文献
5.
Dorn R. Baumgartner A. Goth A. Gutu-Nelle A. Koppenborg J. Rehm W. Schneider R. Schneider S. von Wirth J. Weber D. 《Lightwave Technology, Journal of》1991,9(6):709-714
Mechanically shaped preforms (MSP) have been demonstrated to combine economic non-CVD (chemical vapor deposition) processing and low loss, with a published value of 0.63 dB/km and a size of 30 fkm/preform. Improved processing is proposed which results in a minimum loss of 0.27 dB/km at 1550 nm. Preforms capable of yielding 150 fkm have been produced. Reboiling during preform stretching and fiber pulling is identified as the last remaining problem of the process 相似文献
6.
Wang K. Bryant C. Carlson M. Elmer T. Harris A. Garcia M. Hui C.S. Leong C.K. Reynolds B. Tang R. Weber L. Wenzel J. Wilson G. Becker M. 《Micro, IEEE》1995,15(2):44-49
The MPC105 peripheral component interconnection bridge/memory controller provides a platform-specification-compliant bridge between Power PC microprocessors and the PCI bus. With it, designers can create systems using peripherals already designed for a variety of standard PC interfaces. This bridge chip also integrates a secondary cache controller and high-performance memory controller that supports DRAM or synchronous DRAM and ROM or flash ROM 相似文献
7.
Estimating the virial coefficients of small polar molecules 总被引:2,自引:0,他引:2
We adapt existing models for estimating the second and third virial coefficients of small molecules to the halogenated methanes and ethanes. We compare the results with the abundant new, high-qualityPVT data resulting from the search for alternative refrigerants. The present model provides an accurate method for calculating densities, and therefore it should provide reliable thermodynamic properties and fugacity coefficients. We give equations and parameters useful for estimating the properties of pure refrigerants and their mixtures when noPVT data are available.Nomenclature
B
Second virial coeficient
-
B
12
Mixture cross second virial
-
B
h
Second virial of a hard sphere fluid
-
i
(T)
Temperature function, second virial, Eq. (7)
-
C
Third virial coefficient
-
C
112,C
122
Mixture cross third virials
-
C
h
Third virial of a hard sphere fluid
-
N
Avogadro's number
Virial Coefficients
P
c
Critical pressure
-
P
c12
Characteristic critical pressure of a binary mixture
-
T
c
Critical temperature
-
T
c12
Characteristic critical temperature of a binary mixture
-
T
r
Reduced temperature,T/T
c
-
Parameter measuring polar contribution toB, Eq. (3)
-
b
Volume of a hard sphere molecule
-
f
(f)
Polynomials determining temperature dependence of the nonpolar part ofB
-
k
12
Binary interaction parameter for mixtures, Eq. (9a)
-
c
Critical volume
-
e
Molecular polarizability
-
Dipole moment
-
R
Reduced dipole moment, Eq. (4)
-
R12
Mixture reduced dipole moment, second virial
-
R112,
R122
Mixture reduced dipole moment, third virial
-
Pitzer acentric factor
-
12
Mixture acentric factor
-
(r)
Intermolecular potential
-
c
Critical density (1/c) 相似文献
8.
Universal Access in the Information Society - Helping blind people to build cognitive maps of an environment is one of the aims of several assistive systems. In order to evaluate such assistive... 相似文献
9.
Barycentric coordinates are very popular for interpolating data values on polyhedral domains. It has been recently shown that expressing them as complex functions has various advantages when interpolating two‐dimensional data in the plane, and in particular for holomorphic maps. We extend and generalize these results by investigating the complex representation of real‐valued barycentric coordinates, when applied to planar domains. We show how the construction for generating real‐valued barycentric coordinates from a given weight function can be applied to generating complex‐valued coordinates, thus deriving complex expressions for the classical barycentric coordinates: Wachspress, mean value, and discrete harmonic. Furthermore, we show that a complex barycentric map admits the intuitive interpretation as a complex‐weighted combination of edge‐to‐edge similarity transformations, allowing the design of “home‐made” barycentric maps with desirable properties. Thus, using the tools of complex analysis, we provide a methodology for analyzing existing barycentric mappings, as well as designing new ones. 相似文献
10.
US brokerage firms have shown strong interest in a new alternative for trading of equity options since the 26 May 2000 launch of the International Securities Exchange (ISE), an all-electronic trading platform. Although the collective impact of these adoption decisions led to a successful launch and a formidable competitor to the four established options markets in the US, major brokerage firms differ widely in their usage and adoption rates. 相似文献