全文获取类型
收费全文 | 6746篇 |
免费 | 96篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 53篇 |
综合类 | 14篇 |
化学工业 | 892篇 |
金属工艺 | 73篇 |
机械仪表 | 78篇 |
建筑科学 | 233篇 |
矿业工程 | 18篇 |
能源动力 | 76篇 |
轻工业 | 556篇 |
水利工程 | 20篇 |
石油天然气 | 5篇 |
无线电 | 345篇 |
一般工业技术 | 677篇 |
冶金工业 | 3435篇 |
原子能技术 | 50篇 |
自动化技术 | 322篇 |
出版年
2021年 | 36篇 |
2020年 | 31篇 |
2019年 | 42篇 |
2018年 | 38篇 |
2017年 | 44篇 |
2016年 | 71篇 |
2015年 | 77篇 |
2014年 | 84篇 |
2013年 | 125篇 |
2012年 | 165篇 |
2011年 | 146篇 |
2010年 | 113篇 |
2009年 | 130篇 |
2008年 | 123篇 |
2007年 | 133篇 |
2006年 | 143篇 |
2005年 | 118篇 |
2004年 | 101篇 |
2003年 | 87篇 |
2002年 | 90篇 |
2001年 | 68篇 |
2000年 | 54篇 |
1999年 | 153篇 |
1998年 | 1006篇 |
1997年 | 593篇 |
1996年 | 382篇 |
1995年 | 238篇 |
1994年 | 213篇 |
1993年 | 222篇 |
1992年 | 88篇 |
1991年 | 85篇 |
1990年 | 82篇 |
1989年 | 95篇 |
1988年 | 104篇 |
1987年 | 115篇 |
1986年 | 88篇 |
1985年 | 79篇 |
1984年 | 57篇 |
1983年 | 62篇 |
1982年 | 58篇 |
1981年 | 72篇 |
1980年 | 81篇 |
1979年 | 48篇 |
1978年 | 57篇 |
1977年 | 139篇 |
1976年 | 271篇 |
1975年 | 36篇 |
1974年 | 29篇 |
1973年 | 34篇 |
1971年 | 32篇 |
排序方式: 共有6847条查询结果,搜索用时 15 毫秒
101.
A group of 344 cervices, produced by conisation within a period of 5 1/2 years, were examined for specific effects of contraceptives. In half of all women, who used oral contraceptives, specific lesions such as "siebartige polypoide Hyperplasie" (cribriform polypoid hyperplasia) were found. The findings and their etiology and importance are discussed. 相似文献
102.
Jatinder N. D. Gupta Frank Werner Gunnar Wulkenhaar 《International Transactions in Operational Research》2003,10(3):267-294
This paper considers two-machine open shop problems with secondary criteria where the primary criterion is the minimization of makespan and the secondary criterion is the minimization of the total flow time, total weighted flow time, or total weighted tardiness time. In view of the strongly NP-hard nature of these problems, two polynomially solvable special cases are given and constructive heuristic algorithms based on insertion techniques are developed. A strongly connected neighborhood structure is derived and used to develop effective iterative heuristic algorithms by incorporating iterative improvement, simulated annealing and multi-start procedures. The proposed insertion and iterative heuristic algorithms are empirically evaluated by solving problem instances with up to 80 jobs. 相似文献
103.
Simulation of thermally induced package effects with regard to piezoresistive pressure sensors 总被引:1,自引:0,他引:1
Frank Schilling Werner Langheinrich Kurt Weiblen Dieter Arand 《Sensors and actuators. A, Physical》1997,60(1-3):37-39
Microsystems are on their way out of laboratories into production. One of these microsystems, a piezoresistive pressure sensor developed by Robert Bosch GmbH, is examined within this paper. Obviously, one can detect undesirable temperature effects resulting from the sensor package, which influence the electrical characteristics of the sensor. By means of finite-element modelling (FEM), a simulation of the temperature effects can be managed. It is also possible to search for alternative designs of the sensor package. 相似文献
104.
Robert A. Werner 《Computers & Geosciences》1997,23(10):212
Recurrent relationships for the definitions of fully normalized spherical harmonic coefficients C?n,m and S?n,m are derived and integrated analytically to yield the gravitational potential of a constant-density polyhedron. The algorithm is expressed in a C language computer program. 相似文献
105.
Software Quality Journal - There is a widely accepted paradigm of successful software development, called process oriented software quality management (PSQM). The proponents of PSQM claim that it... 相似文献
106.
Jií Bittner Michael Wimmer Harald Piringer Werner Purgathofer 《Computer Graphics Forum》2004,23(3):615-624
107.
108.
109.
NS Bora PS Bora MT Tandhasetti TP Cirrito HJ Kaplan 《Canadian Metallurgical Quarterly》1996,37(9):1877-1883
PURPOSE: Patients with active pars planitis have increased levels of a 36 kDa protein (p-36) in their circulation. The current studies were undertaken to determine the primary structure of this protein. METHODS: A degenerate oligonucleotide probe based on the amino terminal sequence of p-36 was used to identify a clone from a human spleen cDNA library. The cDNA insert was subcloned into the EcoR1 site of pUC-19, and both strands were sequenced. Southern blot analysis was used to study the genomic hybridization pattern. p-36 cDNA was subcloned in a pSG5 expression vector, and the construct was used to transfect COS-7 cells. RESULTS: The cDNA sequence contained an open reading frame of 966 base pairs encoding a protein of 322 amino acids, an untranslated region of 322 base pairs, and 2693 base pairs at the 5' and 3' ends, respectively. The deduced amino acid sequence showed 96.8% identity with the carboxy-terminal region of a yeast nucleopore complex protein, nup 100. Southern blot analysis of human genomic DNA revealed a simple hybridization pattern. Transfection of p-36 cDNA in COS-7 cells resulted in the presence of p-36 mRNA and expression of protein. CONCLUSIONS: The 36 kDa protein (p-36) detected at increased levels in the blood of patients with active pars planitis was cloned from a human spleen cDNA library. Its deduced amino acid sequence is homologous with the carboxy-terminal region of a nucleopore complex protein. Thus, we refer to this protein as nup36. 相似文献
110.
László Neumann Kreimir Matkovi Attila Neumann & Werner Purgathofer 《Computer Graphics Forum》1998,17(4):235-247
Every rendering process consists of two steps. The first is the computing of luminance values by methods like ray tracing or radiosity, and the second step is the mapping of the computed values to values appropriate for displaying. In the last years, as alternative to simple linear scaling which maps the average value to the medium luminance, some new ways of mapping were introduced. These new methods are based on photography analogies and on human vision models. All existing methods follow, implicitly or explicitly, the reflected light metering principle. The method introduced in this paper is the first that follows the incident light metering used in professional photography and in the movie industry. Actually the irradiances are measured using a set of diffusors, which are placed automatically in the scene, and a linear scale factor based on these measurements is used to map the computed radiances to the display device. The diffusors act as half space integrators, they collect the light energy from all half space directions. The light comes from the primary light sources, or it is the result of various interreflections. The newly introduced method reproduces original colors faithfully even for scenes with very low or very high average reflectivity. 相似文献