全文获取类型
收费全文 | 971篇 |
免费 | 39篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 52篇 |
综合类 | 2篇 |
化学工业 | 262篇 |
金属工艺 | 39篇 |
机械仪表 | 27篇 |
建筑科学 | 16篇 |
能源动力 | 55篇 |
轻工业 | 51篇 |
水利工程 | 2篇 |
石油天然气 | 3篇 |
无线电 | 60篇 |
一般工业技术 | 205篇 |
冶金工业 | 100篇 |
原子能技术 | 35篇 |
自动化技术 | 104篇 |
出版年
2023年 | 12篇 |
2022年 | 14篇 |
2021年 | 30篇 |
2020年 | 10篇 |
2019年 | 17篇 |
2018年 | 13篇 |
2017年 | 20篇 |
2016年 | 25篇 |
2015年 | 17篇 |
2014年 | 36篇 |
2013年 | 52篇 |
2012年 | 39篇 |
2011年 | 72篇 |
2010年 | 61篇 |
2009年 | 42篇 |
2008年 | 59篇 |
2007年 | 49篇 |
2006年 | 47篇 |
2005年 | 33篇 |
2004年 | 27篇 |
2003年 | 39篇 |
2002年 | 22篇 |
2001年 | 13篇 |
2000年 | 15篇 |
1999年 | 10篇 |
1998年 | 49篇 |
1997年 | 26篇 |
1996年 | 20篇 |
1995年 | 20篇 |
1994年 | 16篇 |
1993年 | 10篇 |
1992年 | 13篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 10篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 10篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 4篇 |
1976年 | 7篇 |
1975年 | 2篇 |
1974年 | 4篇 |
排序方式: 共有1013条查询结果,搜索用时 31 毫秒
101.
Satoshi Hiraoka Takeshi Fujii Hideyuki Takakura Yoshihiro Hamakawa 《Solar Energy Materials & Solar Cells》2003,75(3-4):781-786
One-year field experience of an 80 kW PV system on a rooftop of the ROHM Memorial VLSI Research Center at the Ritsumeikan University is reported. All kinds of live technology available materials, c-Si, poly Si and a-Si solar cells are installed on the three tilt angles of 26.5° south, horizontal and north 26.5°. Systematic PV performances have been measured from the beginning of June 2000 to the end of May 2001. Measurements were made mainly on DC output power from four kinds of PV arrays; c-Si south side, a-Si of horizontal and poly Si, a-Si north side. It has been shown from analyses of monthly data on each material that almost 70% of with that in the south side in the annual average. In summer a-Si module yields the maximum output power normalized to 1 kWp. On the contrary c-Si module shows larger output in winter. Some other unique results are demonstrated and discussed. 相似文献
102.
Heat transfer during oscillatory flow in a circular straight tube with a solid‐core tube inserted in its center was numerically simulated. The purpose of the solid‐core tube is to enhance axial heat transfer by increasing the lateral heat transfer effect for high frequency of the oscillatory flow. Simulation results showed that (a) axial heat transfer increases with the increasing diameter of the solid‐core tube, (b) the material of the solid‐core tube does not significantly affect axial heat transfer, and (c) efficiency based on the ratio of heat transfer to the work done is higher than that in a bundle of circular capillary tubes. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(1): 61–74, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20094 相似文献
103.
Ryota Masumoto Ken-ichi Ueno Hirofumi Matsuda Ryuji Nomura Yuichi Okuda 《Journal of Low Temperature Physics》2011,162(5-6):399-406
Crystallization of 4He in aerogels of 90 and 96% porosities shows a dynamical phase transition at around 600 mK due to the competition between thermal fluctuation and disorder: crystals grow via creep at high temperatures and via avalanche at low temperatures. In a very high porosity 99.5% aerogel, however, the transition had not been observed in our previous publication (Nomura et al. in Phys. Rev. Lett. 101:175703, 2008). We improved the spatial resolution of the video image and found that the 99.5% aerogel did have the transition at around 200 mK, which is much lower than those of the lower porosities. The avalanche size is significantly smaller in the 99.5% aerogel. The reduction in the transition temperature and avalanche size may be the consequence of weaker disorder for the crystallization in the very high porosity aerogel. 相似文献
104.
Effects of photoirradiation in UV and VUV regions during plasma exposure to polymers 总被引:1,自引:0,他引:1
Ken Cho Yuichi Setsuhara Kosuke Takenaka Masaharu Shiratani Makoto Sekine Masaru Hori 《Thin solid films》2011,519(20):6810-6814
Interactions between photons irradiated from Ar-O2 mixture plasmas and polymer surfaces were investigated on the basis of depth analyses of chemical bonding states in the nano-surface layer of polyethylene terephthalate (PET) films via hard X-ray photoelectron spectroscopy (HXPES) and conventional X-ray photoelectron spectroscopy (XPS). The PET films were exposed to photons from the Ar-O2 mixture plasmas by covering the PET samples with MgF2 and quartz windows as optical filters for evaluation of photoirradiation effects in ultraviolet (UV) and vacuum ultraviolet (VUV) regions. The HXPES results indicated that the degradation of the chemical bonding states due to photoirradiation in regions was insignificant in deeper regions up to about 50 nm from the surface. Whereas, conventional XPS analysis showed that CO bond, OCO bond and CO bond increased after photoirradiation in UV and VUV regions. These results suggest that the increase in oxygen functionalities (CO bond, OCO bond and CO bond) may be attributed to chemical reactions and/or terminations of scissed bonds via photodecompositions of the polymer with oxygen and/or OH species (oxygen molecules and radicals during plasma exposure and/or oxygen molecules and moisture after taking the PET samples out of the plasma reactor to the ambient air) in the vicinity of the sample surface. 相似文献
105.
W Hiraoka N Vazquez W Nieves-Neira SJ Chanock Y Pommier 《Canadian Metallurgical Quarterly》1998,102(11):1961-1968
We have used a human leukemia cell line that, after homologous recombination knockout of the gp91-phox subunit of the phagocyte respiratory-burst oxidase cytochrome b-558, mimics chronic granulomatous disease (X-CGD) to study the role of oxygen radicals in apoptosis. Camptothecin (CPT), a topoisomerase I inhibitor, induced significantly more apoptosis in PLB-985 cells than in X-CGD cells. Sensitivity to CPT was enhanced after neutrophilic differentiation, but was lost after monocytic differentiation. No difference between the two cell lines was observed after treatment with other apoptosis inducers, including etoposide, ultraviolet radiation, ionizing radiation, hydrogen peroxide, or 7-hydroxystaurosporine. After granulocytic differentiation of both cell lines, CPT still induced apoptosis, suggesting independence from replication in fully differentiated and growth-arrested cells. Pyrrolidine dithiocarbamate (an antioxidant inhibitor of NF-kappaB) and catalase partially inhibited CPT-induced DNA fragmentation in granulocytic-differentiated PLB-985 cells, but had no effect in X-CGD cells. Flow cytometry analysis revealed that reactive oxygen intermediates were generated in CPT-treated PLB-985 cells. These data indicate that oxygen radicals generated by NADPH oxidase may contribute directly or indirectly to CPT-induced apoptosis in human leukemia and in neutrophilic-differentiated cells. 相似文献
106.
Yuichi Miura Kazuo Mori Takayoshi Mamiya Tetsumasa Nakayasu 《Journal of Low Temperature Physics》1998,113(5-6):757-762
We have measured the dissipation of dislocation motion in bcc solid
3
He using the high-Q torsional oscillator technique at 1079 Hz. We observed a broad maximum in the temperature dependence of the dissipation. The maximum of the dissipation can be explained by the theory of Granato and Lucke in which the dislocation mobility depends upon the interactions of dislocations with point defects.
4
He impurities tend to bind to the dislocation lines at low temperatures and pin this dislocation motion. The maximum of the dissipation corresponds to the depinning of the dislocation motion. From the amplitude dependence of the depinning temperature we first obtained the activation energy of 1.03 K of the impurity
4
He atom trapped on the dislocations in bcc solid
3
He at a molar volume of 24.30 cm
3
/mol. The activation energy of the impurity atom in bcc
3
He was found to be larger than the value of 0.7 Kin hcp
4
He. 相似文献
107.
Morphometric and functional brain research is now an integral part of the most concentrated effort in a century to understand some of the most distressing illnesses to which man can fall victim. It will undoubtedly expand. The only ones with anything to fear from this work are those who, for ideological reasons, cannot accept its basic premises. The ethical issues it raises are not in general insurmountable, though the questions posed by the concept of informed consent remain. 相似文献
108.
A Hiraoka A Sugimura T Seki T Nagasawa N Ohta M Shimonishi M Hagiya S Shimizu 《Canadian Metallurgical Quarterly》1997,94(14):7577-7582
Multiple growth factors synergistically stimulate proliferation of primitive hematopoietic progenitor cells. A human myeloid cell line, KPB-M15, constitutively produces a novel hematopoietic cytokine, termed stem cell growth factor (SCGF), possessing species-specific proliferative activities. Here we report the molecular cloning, expression, and characterization of a cDNA encoding human SCGF using a newly developed lambdaSHDM vector that is more efficient for differential and expression cloning. cDNA for SCGF encodes a 29-kDa polypeptide without N-linked glycosylation. SCGF transiently produced by COS-1 cells supports growth of hematopoietic progenitor cells through a short-term liquid culture of bone marrow cells and exhibits promoting activities on erythroid and granulocyte/macrophage progenitor cells in primary semisolid culture with erythropoietin and granulocyte/macrophage colony-stimulating factor, respectively. Expression of SCGF mRNA is restricted to myeloid cells and fibroblasts, suggesting that SCGF is a growth factor functioning within the hematopoietic microenvironment. SCGF could disclose some human-specific mechanisms as yet unidentified from studies on the murine hematopoietic system. 相似文献
109.
Yuichi Maekawa Akio Yamaguchi Makoto Hara Yasuo Sekii 《Electrical Engineering in Japan》1994,114(8):1-12
This paper describes the development of dc XLPE cable. Through a series of material investigations, an XLPE compound containing highly purified special filler was developed. To check the dc insulation performance of the cable insulated with this new material, a prototype cable with 9 mm insulation thickness was manufactured. It was confirmed that the performance of the prototype cable was excellent. Based on the study of the prototype cable, a 250-kV dc cable with 20 mm insulation thickness was designed and manufactured. Through a series of voltage tests, excellent dc insulation performance of the developed cable was verified. 相似文献
110.
Matsumoto S. Hiraoka Y. Ishiyama T. Sakai T. Yachi T. Yamada I. Ito A. Arimoto Y. 《Electron Devices, IEEE Transactions on》1998,45(9):1940-1945
The device characteristics of a quasi-SOI power MOSFET were investigated to obtain its optimum device structure. The oxide at the original bottom surface of the bulk power MOSFET of the quasi-SOI power MOSFET formed by reversed silicon wafer direct bonding acts as the buried oxide of the conventional SOI power MOSFET. The short channel effect of the quasi-SOI power MOSFET was larger than that in the conventional SOI power MOSFET. It was suppressed by increasing the width of the oxide in the body region, and the parasitic bipolar effect was suppressed by decreasing it. We also propose a new device structure which can suppress the short channel effect and parasitic bipolar effect of a quasi-SOI power MOSFET based on the results of these experiments 相似文献