全文获取类型
收费全文 | 6140篇 |
免费 | 100篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 306篇 |
综合类 | 3篇 |
化学工业 | 1033篇 |
金属工艺 | 180篇 |
机械仪表 | 138篇 |
建筑科学 | 86篇 |
能源动力 | 153篇 |
轻工业 | 412篇 |
水利工程 | 29篇 |
石油天然气 | 6篇 |
无线电 | 602篇 |
一般工业技术 | 1057篇 |
冶金工业 | 1774篇 |
原子能技术 | 123篇 |
自动化技术 | 349篇 |
出版年
2023年 | 18篇 |
2022年 | 36篇 |
2021年 | 88篇 |
2020年 | 41篇 |
2019年 | 39篇 |
2018年 | 58篇 |
2017年 | 58篇 |
2016年 | 57篇 |
2015年 | 64篇 |
2014年 | 77篇 |
2013年 | 185篇 |
2012年 | 170篇 |
2011年 | 230篇 |
2010年 | 155篇 |
2009年 | 183篇 |
2008年 | 189篇 |
2007年 | 204篇 |
2006年 | 197篇 |
2005年 | 176篇 |
2004年 | 166篇 |
2003年 | 158篇 |
2002年 | 165篇 |
2001年 | 153篇 |
2000年 | 129篇 |
1999年 | 158篇 |
1998年 | 661篇 |
1997年 | 412篇 |
1996年 | 298篇 |
1995年 | 209篇 |
1994年 | 206篇 |
1993年 | 167篇 |
1992年 | 90篇 |
1991年 | 93篇 |
1990年 | 90篇 |
1989年 | 77篇 |
1988年 | 73篇 |
1987年 | 57篇 |
1986年 | 69篇 |
1985年 | 82篇 |
1984年 | 52篇 |
1983年 | 58篇 |
1982年 | 43篇 |
1981年 | 52篇 |
1980年 | 52篇 |
1979年 | 30篇 |
1978年 | 24篇 |
1977年 | 54篇 |
1976年 | 56篇 |
1975年 | 31篇 |
1973年 | 23篇 |
排序方式: 共有6251条查询结果,搜索用时 31 毫秒
991.
The thermo-optic constants of AgGaSe(2) have been measured at 2.052, 3.3913, 5.2955, and 10.5910 mum. These results combined with values reported in the literature were used to construct the thermo-optic dispersion formula that correctly reproduces the temperature-dependent phase-matching conditions for second-harmonic generation and sum-frequency generation of a CO(2) laser as well as the thermally induced lensing effects for the 2.05-mum pumped parametric oscillators. 相似文献
992.
AA Sakrana Y Tanaka K Udoh K Hisatsune M Atsuta K Yasuda 《Canadian Metallurgical Quarterly》1997,16(2):144-155
Hephaestus (or Hephaistos) is an Olympian Greek god, the divine smith, famed for inventions, who taught men glorious crafts. The fixed epithet for Hephaestus, used from the eighth century B.C. by Homer, Hesiod, and other ancient authors until the fifth century A.D., is "Amphiguéeis," i.e., with both feet crooked. He is also called "Kullopodíou," i.e., clubfooted. His body and his gait were described by Homer: "He spake, and from the anvil rose, a huge, panting bulk, halting the while, but beneath him his slender legs moved nimbly ... and with a sponge wiped his face and his two hands withal, and his mighty neck and shaggy breast, ... and grasped a stout staff, and went forth halting; but there moved swiftly to support their lord handmaidens wrought of gold in the semblance of living maids." His anomaly was congenital, as we learn from Hephaestus himself ("I was born misshapen") and from his mother Hera ("But my son Hephaestus whom I bare was weakly among all the blessed gods and shrivelled of foot."). Vase paintings of the sixth century B.C. depict Hephaestus' lameness, but his lameness is not emphasized in the fifth century and thereafter. It is most likely that bilateral congenital clubfeet made Hephaestus lame. Two sons of Hephaestus, Palaemonius and Periphetes, were also reported as having deformed feet. 相似文献
993.
P-element-induced recombination in Drosophila melanogaster occurs premeiotically. Recombinants are therefore expected to accumulate in the stem cells of the germline of P-element-carrying males. We show that both the recombination frequency and the incidence of "clustering" increase with the age of males carrying various P-element derivatives. The combination of end-deleted elements can lead to average recombination frequencies >50% with individual instances of 100% recombination. These elements also lowered the fertility of the carriers. We investigated these features by constructing an analytical and a computer simulation model of the course of events in the germline, incorporating the recently proposed hybrid element insertion (HEI) model of P-element activity. The model is able to predict extreme recombination levels, segregation ratio biases and lowered fertility through cell death in a single analysis. 相似文献
994.
M Sakuraba J Tanaka S Ikeda I Kigawa S Fukuda Y Wanibuchi 《Canadian Metallurgical Quarterly》1997,45(11):1893-1897
A 70-year-old woman underwent radical mastectomy for carcinoma of the left breast in 1982. Postoperative radiation therapy was given in a total dose of 50 Gy for parasternal and left subclavian nodes. Symptoms of heart failure such as exertional dyspnea, facial edema, and hepatomegaly manifested in 1992. Cardiac catheterization revealed marked elevation of mean right atrial pressure and right ventricular end-diastolic pressure. The pressure wave form of the right ventricle showed the so called "dip and plateau" feature. Pericardiectomy without using extracorporeal circulation was performed in 1994. Operative findings and pathological study results were compatible with radiation-induced constrictive pericarditis. She rapidly recovered from heart failure after this operation, and has done very well to date. 相似文献
995.
M Tanaka O Schmidlin SL Yi AW Bollen RC Morris 《Canadian Metallurgical Quarterly》1997,94(26):14748-14752
The stroke-prone spontaneously hypertensive rat (SHRSP) is a genetically determined model of "salt-sensitive" stroke and hypertension whose full phenotypic expression is said to require a diet high in Na+ and low in K+. We tested the hypothesis that dietary Cl- determines the phenotypic expression of the SHRSP. In the SHRSP fed a normal NaCl diet, supplementing dietary K+ with KCl exacerbated hypertension, whereas supplementing either KHCO3 or potassium citrate (KB/C) attenuated hypertension, when blood pressure (BP) was measured radiotelemetrically, directly and continually. Supplemental KCl, but not KB/C, induced strokes, which occurred in all and only those rats in the highest quartiles of both BP and plasma renin activity (PRA). PRA was higher with KCl than with KB/C. These observations demonstrate that with respect to both severity of hypertension and frequency of stroke the phenotypic expression of the SHRSP is (i) either increased or decreased, depending on whether the anionic component of the potassium salt supplemented is, or is not, Cl-; (ii) increased by supplementing Cl- without supplementing Na+, and despite supplementing K+; and hence (iii) both selectively Cl--sensitive and Cl--determined. The observations suggest that in the SHRSP selectively supplemented with Cl- the likelihood of stroke depends on the extent to which both BP and PRA increase. 相似文献
996.
997.
Modeling 3D origami pieces using conventional software is laborious due to the geometric constraints imposed by the complicated layered structure. Targeting origami models used in visual content such as CG illustrations and movies, we propose an interactive system that dramatically simplifies the modeling of 3D origami pieces with plausible outer shapes, while omitting accurate inner structures. By focusing on flat origami models with a front‐and‐back symmetry commonly found in traditional artworks, our system realizes easy and quick modeling via single‐view interface; given a reference image of the target origami piece, the user draws polygons of planar faces onto the image, and assigns annotations indicating the types of folding operations. Our system automatically rectifies the manually‐specified polygons, infers the folded structures that should yield the user‐specified polygons with reference to the depth order of layered polygons, and generates a plausible 3D model while accounting for gaps between layers. Our system is versatile enough for modeling pseudo‐origami models that are not realizable by folding a single sheet of paper. Our user study demonstrates that even novice users without the specialized knowledge and experience on origami and 3D modeling can create plausible origami models quickly. 相似文献
998.
Liu Cong Froemel Joerg Chen Jianlin Tsukamoto Takashiro Tanaka Shuji 《Microsystem Technologies》2019,25(2):487-497
Microsystem Technologies - This paper reports a laterally vibrating MEMS resonant vacuum sensor which senses ambient pressure based on the squeeze-film damping effect. The single-anchored... 相似文献
999.
Ono Taishi Kubo Hiroyuki Tanaka Kenichiro Funatomi Takuya Mukaigawa Yasuhiro 《计算可视媒体(英文)》2019,5(4):325-336
Computational Visual Media - In this paper, we present a practical method for reconstructing the bidirectional reflectance distribution function (BRDF) from multiple images of a real object... 相似文献
1000.
Kimiyoshi Naito Keiichi Shirasu Yoshihisa Tanaka 《Fatigue & Fracture of Engineering Materials & Structures》2020,43(7):1461-1472
It is crucial to understand the characteristic fatigue crack initiation and its growth mechanisms, as well as the relationship between the mechanical properties and the fatigue damage evolution in fibre metal laminates (FMLs). Two types of FML were studied in this work: a polyacrylonitrile‐based carbon fibre epoxy matrix composite sandwiched by Ti‐6Al‐4V (Ti‐alloy) sheets (IMS60‐Ti) and a pitch‐based carbon fibre epoxy matrix composite sandwiched by Ti‐alloy sheets (K13D‐Ti). The static and fatigue mechanical properties of IMS60‐Ti and K13D‐Ti were investigated. The increased failure strain of the FML was greater than that of carbon fibre‐reinforced polymer (CFRP) matrix composites. The fatigue life of IMS60‐Ti was much longer than that of K13D‐Ti. The fatigue damage process in IMS60‐Ti was related to the fatigue creep behaviour of the Ti‐alloy face sheet and mode II cracking at the CFRP/Ti‐alloy interface, and the damage in K13D‐Ti was related to the K13D CFRP laminate. 相似文献