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81.
Stuart A. Smith Brock Gause David Plumley Masao J. Drexel 《Journal of Materials Engineering and Performance》2012,21(12):2638-2642
Medical device fractures during gamma and electron beam (eBeam) sterilization have been reported. Two common factors in these device fractures were a constraining force and the presence of fluorinated ethylene propylene (FEP). This study investigated the effects of eBeam sterilization on constrained light-oxide nitinol wires in FEP. The goal was to recreate these fractures and determine their root cause. Superelastic nitinol wires were placed inside FEP tubes and constrained with nominal outer fiber strains of 10, 15, and 20%. These samples were then subjected to a range of eBeam sterilization doses up to 400 kGy and compared with unconstrained wires also subjected to sterilization. Fractures were observed at doses of >100 kGy. Analysis of the fracture surfaces indicated that the samples failed due to irradiation-assisted stress-corrosion cracking (IASCC). This same effect was also observed to occur with PTFE at 400 kGy. These results suggest that nitinol is susceptible to IASCC when in the presence of a constraining stress, fluorinated polymers, and irradiation. 相似文献
82.
Toru Nagaoka Yoshiaki Morisada Masao Fukusumi Tadashi Takemoto 《Metallurgical and Materials Transactions B》2010,41(4):864-871
To obtain sound butt-joints of 5056 aluminum alloy rods, ultrasonic-assisted soldering was conducted using Zn-18Sn and Zn-60Sn
alloys. Each solder foil was inserted between rods of 5056 aluminum alloy. Ultrasonic vibration was propagated to faying surfaces
at soldering temperatures below the liquidus temperature of the solder alloys, and then the samples were air cooled to room
temperature. The optimum vibration time at the soldering temperature must be more than 2 seconds to have complete wetting
and less than 4 seconds to avoid excessive dissolution of the 5056 alloy. The 5056 alloy joints soldered using quasi-melting.
Zn-Sn alloys showed greater strength than the joints soldered at the temperatures over its respective liquidus temperature.
As the soldering temperature was increased, the increased formation of the intermetallic compound Mg2Sn or phases containing Mg generated by dissolution of 5056 into the solder layer decreased the joint strength. Ultrasonic-assisted
soldering at an optimum temperature between solidus and liquidus of the Zn-Sn alloys is an important consideration for producing
sound joints with sufficient strength. 相似文献
83.
Takuya Noguchi Toshihiro Shimada Takashi Chiba Masao Terada Tetsuya Hasegawa 《Diamond and Related Materials》2010,19(2-3):107-109
We have carried out very high temperature heat treatment at 1400–2700 °C of about 10 nm-thick amorphous carbon thin films deposited on refractory substrates MgO, Al2O3, and yttria-stabilized zirconia (YSZ) using pulsed laser deposition techniques. After the annealing, a few nanometer scale sp2 crystallization of the films and a large corrugation with a height of more than 1 μm were observed by Raman spectroscopy analysis and optical/atomic force microscopes, respectively. The corrugation is probably caused by the formation of gases at the film/substrate interface during the heat treatment. 相似文献
84.
Tshering Cigay Dorji El-sayed Atlam Susumu Yata Masao Fuketa Kazuhiro Morita Jun-ichi Aoe 《Knowledge and Information Systems》2011,27(1):141-161
Field Association (FA) Terms—words or phrases that serve to identify document fields are effective in document classification,
similar file retrieval and passage retrieval. But the problem lies in the lack of an effective method to extract and select
relevant FA Terms to build a comprehensive dictionary of FA Terms. This paper presents a new method to extract, select and
rank FA Terms from domain-specific corpora using part-of-speech (POS) pattern rules, corpora comparison and modified tf-idf weighting. Experimental evaluation on 21 fields using 306 MB of domain-specific corpora obtained from English Wikipedia dumps
selected up to 2,517 FA Terms (single and compound) per field at precision and recall of 74–97 and 65–98. This is better than
the traditional methods. The FA Terms dictionary constructed using this method achieved an average accuracy of 97.6% in identifying
the fields of 10,077 test documents collected from Wikipedia, Reuters RCV1 corpus and 20 Newsgroup data set. 相似文献
85.
K Kimura M Yasaka K Minematsu K Wada M Uchino K Yonemura J Ogata T Yamaguchi 《Canadian Metallurgical Quarterly》1998,24(8):1121-1124
BACKGROUND: Gunshot wounds to the kidney have been managed traditionally by surgical exploration. Concerns over increased nephrectomy rates and unnecessary explorations have placed this method under scrutiny. Selective renal exploration based on solid clinical and radiographic criteria may be a safer alternative and deserves evaluation. METHODS: The medical records of 52 consecutive patients with renal gunshot wounds, who were managed between September 1994 and August 1995 by a protocol of selective exploration, were reviewed. Renal injuries were explored only if they involved the hilum or were accompanied by signs of continued bleeding. Main outcome measures were the numbers of kidneys lost, as well as the morbidity and mortality related to the management of the renal injury. RESULTS: Three patients died from associated injuries shortly after admission. Fifteen patients suffered complications but only two had complications directly associated with the renal injury. Thirty-two patients underwent renal exploration and 17 of them required nephrectomy for major renovascular or parenchymal trauma (grade IV and V). Renal exploration was successfully avoided in the remaining 20 patients. No kidneys were lost unnecessarily as a result of this policy. CONCLUSION: Mandatory exploration of all gunshot wounds to the kidney is not necessary. Injuries that produce stable peripheral haematomas do not require exploration. 相似文献
86.
Soluble polyimides (PIs) were prepared as random or multiblock types with 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (s‐BPDA) as acid dianhydride components and 4,4′‐bis(m‐aminophenoxy) diphenyl sulfone (m‐BAPS) as a diamine component by a one‐pot process and used to improve the brittleness of the cyanate ester resin. Random‐type PIs were more effective as modifiers than multiblock‐type PIs. The morphologies of the modified resins depended on PI structure, molecular weight, and concentration. The most effective modification of the cyanate ester resin was attained because of a heterogeneous phase structure composed of a flat matrix phase and phase‐inverted structures of the modified resin; a 15 wt % inclusion of a random PI (weight‐average molecular weight = 63,400) composed of 6FDA, s‐BPDA, and m‐BAPS (0.5/0.5/1.0 molar ratio) led to a 65% increase in the fracture toughness for the modified resin with a slight loss of flexural strength and a retention of flexural modulus and glass‐transition temperature, compared with the values for the unmodified resin. Water absorptivity of the modified resin was comparable to that of the unmodified resin up to 400 h, and then, water absorption of the modified resins increased considerably. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1–11, 2003 相似文献
87.
Gao-Chao Lai Masao Takahashi Kohji Nobugai Fumikazu Kanamaru 《Journal of the American Ceramic Society》1989,72(12):2310-2313
Solid-solution thin films, Mo1−x Nbx N, with B1 (NaCl) structure have been deposited on substrates at 450°C by reactive sputtering of composite targets with Mo and Nb metals in an equimolar Ar and N2 gas mixture. The lattice parameter of the solid solution increased linearly with an increase of Nb content, x . The superconducting transition temperature, T c , of the Mo-rich films ( x ≦ 0.12) was around 6 K, which was lower than that expected from theoretical prediction. The residual resistivity ratio, r =ρ(300 K)/ρ(20 K), of the films varied with x , and a minimum value of r was observed in the vicinity of x = 0.5. 相似文献
88.
Nawalage F. Cooray Katsumi Kushiya Atsushi Fujimaki Ichiro Sugiyama Tadayuki Miura Daisuke Okumura Masao Sato Mineo Ooshita Osamu Yamase 《Solar Energy Materials & Solar Cells》1997,49(1-4)
In this study, two deposition methods (i.e. MOCVD and sputtering methods) to prepare n-type ZnO window layers for CIGS-based thin-film solar cells are discussed. In order to make ZnO : Al transparent conductive oxide (TCO) films prepared by DC magnetron sputtering comparable to ZnO : B TCO prepared by MOCVD, a new ZnO sputtering process is proposed by introducing a multilayer structure. Using these films, CIGS thin-film solar cells with efficiencies of greater than 14% have been fabricated with an active area of 3.2 cm2. This structure was adapted to fabricate CIGS thin-film mini-modules with efficiencies around 11% having aperture area of 50 cm2. 相似文献
89.
Five sterylglycosides (acylmono-, mono-, di tri- and tetraglycosylsterol) and a saponin were isolated from Adzuki beans and
characterized. In the glycosylsterols, the principal component sterols were sitosterol and stigmasterol; the major sugar component
was glucose. The glucose units were shown to be linked by β1,6-bonds. The three oligoglycosylsterols were shown to be gentiobiosylsterol,
gentiotriosylsterol and gentiotetraosylsterol; the latter two are novel sterylglycosides. The saponin was identified as glucopyranosyl-(β1→2)-glucopyranurosyl-(β1→3′)-soyasapogenol
B (Azukisaponin I) which had previously been found in Adzuki beans. 相似文献
90.