全文获取类型
收费全文 | 3038篇 |
免费 | 90篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 75篇 |
综合类 | 12篇 |
化学工业 | 672篇 |
金属工艺 | 99篇 |
机械仪表 | 68篇 |
建筑科学 | 127篇 |
矿业工程 | 11篇 |
能源动力 | 47篇 |
轻工业 | 335篇 |
水利工程 | 17篇 |
石油天然气 | 4篇 |
无线电 | 190篇 |
一般工业技术 | 547篇 |
冶金工业 | 620篇 |
原子能技术 | 38篇 |
自动化技术 | 271篇 |
出版年
2022年 | 33篇 |
2021年 | 49篇 |
2020年 | 19篇 |
2019年 | 30篇 |
2018年 | 40篇 |
2017年 | 40篇 |
2016年 | 38篇 |
2015年 | 43篇 |
2014年 | 50篇 |
2013年 | 130篇 |
2012年 | 88篇 |
2011年 | 123篇 |
2010年 | 67篇 |
2009年 | 79篇 |
2008年 | 119篇 |
2007年 | 95篇 |
2006年 | 80篇 |
2005年 | 61篇 |
2004年 | 49篇 |
2003年 | 64篇 |
2002年 | 72篇 |
2001年 | 81篇 |
2000年 | 64篇 |
1999年 | 58篇 |
1998年 | 179篇 |
1997年 | 119篇 |
1996年 | 91篇 |
1995年 | 76篇 |
1994年 | 70篇 |
1993年 | 49篇 |
1992年 | 47篇 |
1991年 | 50篇 |
1990年 | 27篇 |
1989年 | 36篇 |
1988年 | 45篇 |
1987年 | 33篇 |
1986年 | 32篇 |
1985年 | 32篇 |
1984年 | 40篇 |
1983年 | 28篇 |
1982年 | 31篇 |
1981年 | 29篇 |
1980年 | 30篇 |
1979年 | 29篇 |
1978年 | 30篇 |
1977年 | 53篇 |
1976年 | 66篇 |
1974年 | 28篇 |
1973年 | 23篇 |
1972年 | 23篇 |
排序方式: 共有3133条查询结果,搜索用时 31 毫秒
1.
2.
In advancement of Pyrosil®‐technology a new kind of precursor delivery was developed, build and tested on real substrates. A Lab‐demonstrator was build to demonstrate the resources of the technology. 相似文献
3.
The aim of this work was to determine the principal mechanical parameters of a thin film on a substrate, i.e. Young's modulus, Poisson's ratio, intrinsic stress, and coefficient of linear thermal expansion. First, standard experiments possibly suitable for this purpose were investigated theoretically. The margin of error of the mechanical parameters determined was estimated as dependent on the geometrical conditions, substrate properties, and error in the respective measurements. In addition, the homogeneity and stability of the parameters were taken into account, for instance inhomogeneity of the film thickness and possible modification of substrate parameters during film growth. To obtain meaningful results, the accuracy of the measurements as well as the homogeneity and stability of several geometrical and physical parameters in general must be extremely high. However, the experimental conditions were found to fulfill these requirements. 相似文献
4.
5.
J.-P. Han S.M. Koo E.M. Vogel E.P. Gusev C. DEmic C.A. Richter J.S. Suehle 《Microelectronics Reliability》2005,45(5-6):783
Anomalous threshold voltage roll-up behavior, commonly referred as reverse short channel effect (RSCE), has been observed in high-k (HfO2 on SiON buffer, Al2O3 on SiON buffer) gated submicron nMOSFETs, while the SiO2 or SiON control samples show normal short channel effect (SCE) behavior. The possible causes such as inhomogeneous channel doping profile and gate oxide thickness variation near S/D ends have been ruled out. The results indicate that interface trap density that dependents on channel length is the main cause of the RSCE observed here. In addition, oxide charge also plays a role. 相似文献
6.
Corrosion monitoring in district heating systems has traditionally been performed by using off-line methods, such as weight loss. The disadvantage is that the method is very slow, especially in low-corrosive environments, and that it only provides information about the past corrosion (accumulated over period of time). The purpose of the work is to test on-line monitoring methods in geothermal hot water in the district heating system in Reykjavik, Iceland. Geothermal water poses certain problems with regards to corrosion monitoring due to low conductivity, high pH and the presence of sulphide. These conditions make the geothermal environment low corrosive. However, a quality control is needed, especially since the sulphide causes the steel pipes to be more vulnerable towards localized corrosion. The methods used in this study were: linear polarization resistance (LPR), harmonic analysis (HA), electrochemical noise (EN) and zero resistance ammetry (ZRA). The Pitting Factor was measured with EN and showed promising results for measuring-localized corrosion on-line. A crevice corrosion cell also gave good results but had a low lifetime. However, the results of a galvanic corrosion cell (Fe/Cu) proved more difficult to interpret since they were dependent both on the dissolved oxygen and the sulphide level. 相似文献
7.
Hydroelectric generators of less than 20 kilowatts can be in remote areas served only by a single-phase line. For high efficiency and low cost, a three-phase induction generator should be used. This three-phase generator can operate with balanced voltages and currents when the ``phase-splitting' circuit uses two capacitors connetted to two different single-phase voltage sources. 相似文献
8.
For pt.I. see ibid., vol.8, no.3, p.36-43 (1991). Contactless tools for testing inside dynamic RAMs, including hot-spot detection, emission microscopy, scanning laser microscopy, and submicron electron beam testing, are described. Basic principles and experimental setups are described. The utility of the techniques is assessed 相似文献
9.
JM Bach H Otto GT Nepom G Jung H Cohen J Timsit C Boitard PM van Endert 《Canadian Metallurgical Quarterly》1997,10(4):375-386
Tissue composition and the distribution of body mass are described for four genera of East African Bovidae (Madoqua, Gazella, Damaliscus, Hippotragus) with supporting data from four others (Neotragus, Oryx, Tragelaphus, Connochaetes). These species are high in muscle mass, an adaptation convergent with other high-speed terrestrial cursors, bounders, and saltators. The segments below the elbow/cubitus and knee/stifle/genu joints in small bovids are both lighter in percent of total body mass (8.6% TBM) and less heavily muscled (10-15% of total limb musculature) than those segments in macaques (13.6% TBM, 20-25% of the limb musculature). Bovid species differ from one another in the regional distribution of muscle mass. Madoqua kirkii (4-5 kg) concentrates muscle in the lumbar extensors and hindlimbs; large species such as Damaliscus doreas (50-60 kg) and Hippotragus niger (160-220 kg) distribute it more evenly between the lumbar and cervical regions and between the hindlimbs and forelimbs. Gazella dorcas (10-20 kg) is quantitatively intermediate in those characteristics. The redistribution of muscle mass with increasing size correlates with the loss of axial bending of the vertebral column: in small, hindlimb dominant, 'dorsomobile' species such as Madoqua sagittal mobility increases stride length through 'extended' suspension; in large 'dorsostable' species such as Damaliscus and Hippotragus the vertebral column resists bending, consequently abbreviating or omitting this non-contact phase of the gait cycle. Locomotor adaptation as it is reflected in size, shape, and musculoskeletal structure is the key to habitat choice, dietary specialization, social structure, and male agonistic behavior and, therefore, central to the fabric of behavioral ecology. 相似文献
10.
S Schumacher H Volkmer F Buck A Otto A Tarnók S Roth FG Rathjen 《Canadian Metallurgical Quarterly》1997,136(4):895-906
Chicken acidic leucine-rich EGF-like domain containing brain protein (CALEB) was identified by combining binding assays with immunological screens in the chicken nervous system as a novel member of the EGF family of differentiation factors. cDNA cloning indicates that CALEB is a multidomain protein that consists of an NH2-terminal glycosylation region, a leucine-proline-rich segment, an acidic box, a single EGF-like domain, a transmembrane, and a short cytoplasmic stretch. In the developing nervous system, CALEB is associated with glial and neuronal surfaces. CALEB is composed of a 140/130-kD doublet, an 80-kD band, and a chondroitinsulfate-containing 200-kD component. The latter two components are expressed in the embryonic nervous system and are downregulated in the adult nervous system. CALEB binds to the extracellular matrix glycoproteins tenascin-C and -R. In vitro antibody perturbation experiments reveal a participation of CALEB in neurite formation in a permissive environment. 相似文献