全文获取类型
收费全文 | 4680篇 |
免费 | 217篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 134篇 |
综合类 | 15篇 |
化学工业 | 1088篇 |
金属工艺 | 85篇 |
机械仪表 | 82篇 |
建筑科学 | 245篇 |
矿业工程 | 7篇 |
能源动力 | 113篇 |
轻工业 | 581篇 |
水利工程 | 37篇 |
石油天然气 | 27篇 |
无线电 | 333篇 |
一般工业技术 | 762篇 |
冶金工业 | 627篇 |
原子能技术 | 29篇 |
自动化技术 | 733篇 |
出版年
2023年 | 62篇 |
2022年 | 93篇 |
2021年 | 132篇 |
2020年 | 82篇 |
2019年 | 73篇 |
2018年 | 94篇 |
2017年 | 103篇 |
2016年 | 145篇 |
2015年 | 128篇 |
2014年 | 152篇 |
2013年 | 239篇 |
2012年 | 204篇 |
2011年 | 294篇 |
2010年 | 232篇 |
2009年 | 190篇 |
2008年 | 213篇 |
2007年 | 189篇 |
2006年 | 175篇 |
2005年 | 151篇 |
2004年 | 117篇 |
2003年 | 102篇 |
2002年 | 104篇 |
2001年 | 84篇 |
2000年 | 73篇 |
1999年 | 84篇 |
1998年 | 156篇 |
1997年 | 98篇 |
1996年 | 87篇 |
1995年 | 73篇 |
1994年 | 50篇 |
1993年 | 53篇 |
1992年 | 41篇 |
1991年 | 27篇 |
1990年 | 34篇 |
1989年 | 40篇 |
1988年 | 35篇 |
1987年 | 36篇 |
1986年 | 21篇 |
1985年 | 40篇 |
1984年 | 26篇 |
1983年 | 30篇 |
1982年 | 23篇 |
1981年 | 19篇 |
1979年 | 22篇 |
1976年 | 39篇 |
1974年 | 26篇 |
1973年 | 21篇 |
1971年 | 20篇 |
1970年 | 19篇 |
1966年 | 23篇 |
排序方式: 共有4898条查询结果,搜索用时 15 毫秒
1.
Nano-particulate copper and indium metal layers of 1-2 μm have been deposited by non-vacuum techniques such as doctor blade, screen printing and electrospray using alcoholic suspension pastes. Electrospray showed a high efficiency of material usage and yielded the most uniform morphology. The metal precursor layers were subjected to a thermal treatment (500-600 °C) in selenium vapor to convert the porous metal layers into CuInSe2 compound layers. The chemical conversion, investigated by X-ray diffraction, showed the presence of the In2O3 impurity phase in the precursor as well as in the selenized layers. 相似文献
2.
Wilhelm Heinrichs 《Journal of scientific computing》1991,6(1):1-19
We introduce a stabilized treatment of spectral methods. The condition number of the spectral systems is highly improved. Elliptic and biharmonic problems are considered. Suitable interpolants in the case of inhomogeneous Dirichlet boundary conditions are presented. For a direct solver the improvements with respect to rounding error propagation are numerically demonstrated. 相似文献
3.
4.
J Lorenz K Wilhelm M Kessler C Peschel U Schwulera R Lissner WG Struff E Huland C Huber WE Aulitzky 《Canadian Metallurgical Quarterly》1996,2(7):1115-1122
Safety, local and systemic immunomodulation, and tumor response to treatment with aerosolized natural interleukin 2 (nIL-2) applied five times a day were studied in a Phase I trial in 16 patients with pulmonary malignancies refractory to conventional therapy. The toxicity of inhaled nIL-2 was different from that observed after systemic administration. Reversible airway irritation causing a nonproductive cough represented the dose-limiting toxicity. Mild to moderate reduction of the vital capacity and forced expiratory volume (FEV1) with minor effects on relative FEV1, peak expiratory flow, airway resistance, and PaO2 was experienced by individual patients. In 14 patients suffering from pulmonary metastases due to renal cell cancer, one durable complete response, one partial response, and one mixed response were observed. Inhalation of nIL-2 aerosol resulted in a dose-dependent expansion of pulmonary immunocompetent cells in bronchoalveolar lavage fluid. Posttreatment bronchoalveolar lavage showed an activated lymphocyte phenotype with increased HLA-DR expression. The only systemic biological effect detectable in peripheral blood was a marked increase of soluble interleukin 2 receptor serum levels. We conclude that treatment with aerosolized nIL-2 is an effective means for site-specific immunomodulation and deserves further investigation for the treatment of malignant and inflammatory lung disease. 相似文献
5.
6.
SecA is a dynamic protein that undergoes ATP-dependent membrane cycling to drive protein translocation across the Escherichia coli inner membrane. To understand more about this process, azide-resistant (azi) and signal sequence suppressor (prlD) alleles of secA were studied. We found that azide resistance is cold sensitive because of a direct effect on protein export, suggesting that SecA-membrane interaction is regulated by an endothermic step that is azide inhibitable. secG function is required for expression of azide-resistant and signal sequence suppressor activities of azi and prlD alleles, and in turn, these alleles suppress cold-sensitive and export-defective phenotypes of a secG null mutant. These remarkable genetic observations support biochemical data indicating that SecG promotes SecA membrane cycling and that this process is dependent on an endothermic change in SecA conformation. 相似文献
7.
Sustaining Rural Landscapes: the role of integrated tourism 总被引:2,自引:0,他引:2
The aim of a European Union-funded research project entitled 'Supporting and Promoting Integrated Tourism in Europe's Lagging Rural Regions' (SPRITE) is to analyse and develop the potential for better-integrated tourism in the rural landscapes of Europe. Integrated tourism can be defined as that which is explicitly linked to the localities in which it takes place and, in practical terms, has clear connections with local resources, activities, products, production and service industries, and a participatory local community. Enhancing the sustainable economic potential of rural landscapes requires partnerships among rural people and the sustainable yet productive use of rural resources. A 'culture economy' approach to integrated tourism is proposed, which emphasizes the importance of local identity, the strategic commodification of resources and of place, and the importance of extra-local forces in enabling local activities. It is suggested that this approach may represent a shift beyond more traditional approaches to rural development. 相似文献
8.
Pharmacological interactions are important when nuclear medical procedures are applied to patients under drug therapy, or drug provocation. This study compares in baboon models (regional) cerebral blood flow [(r)CBF] results from 99mTc-HMPAO and 123I-iodoamphetamine [123I(IMP)] each with and without acetazolamide, the latter a suggested drug for testing cerebrovascular reserve. Expected differences in cerebral uptake were observed between the two radio-tracers without acetazolamide. The increase in tracer uptake resulting from acetazolamide is significantly enhanced for 123I(IMP), which could have diagnostic implications. 相似文献
9.
Hamid R. Parsaei Mickey R. Wilhelm Sai S. Kolli 《Computers & Industrial Engineering》1993,25(1-4):357-360
Traditional economic evaluation methods concentrate on maximizing or minimizing a single objective such as net present value and pay back period. In the last decade, there has been an increased awareness of the need to consider multiple attributes in the evaluation of advanced manufacturing systems. Various methods have recently been developed for the evaluation of CIM systems. This paper discusses multiattribute methods for justification of CIM systems and outranking methods including ELECTRE, ORESTE, and PROMETHEE. 相似文献
10.
The bulk modification of SBS rubber with maleic anhydride in a mixing chamber of a Haake rheomixer was studied. The effect of temperature, maleic anhydride, and benzoyl peroxide concentrations on the grafting efficiency was evaluated. High grafting efficiency was achieved when the ratio of peroxide and maleic anhydride concentration was high. On the other hand, on this condition high insoluble fraction was generated. The addition of a diamine, 4,4′‐diaminediphenylmethane to the reaction mixture minimizes the amount of insoluble polymer. However, the grafted MAH content also decreases. The graft copolymer was characterized by infrared spectroscopy and the grafting extension was determined by titration. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2953–2960, 2002; DOI 10.1002/app.10355 相似文献