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41.
We have grown thin carbon films by pulsed laser deposition and have investigated the extent to which the properties of such
films, as well as the processes responsible for these properties, are laser wavelength dependent. Films were grown by ablating
material from a graphite target onto room temperature Si(100) substrates with 1064 and 248 nm laser radiation. The films were
analyzed byin situ electron energy loss spectroscopy and byex situ Raman spectroscopy. The results indicated that films grown with 1064 nm ablation were graphitic, while those grown with 248
nm radiation were diamond-like. We have also examined the mass and kinetic energy distributions of the particles ejected from
graphite by the two laser wavelengths. The results indicated that irradiation of graphite with 1064 nm laser radiation results
in the ejection of a series of carbon cluster ions C
n
+
(1 ≤ n ≤ 30) with mean kinetic energies less than 5 eV. Ablation of graphite with 248 nm radiation results in the ejection
of primarily C
2
+
and C
3
+
with mean kinetic energies of 60 and 18 eV, respectively. These results suggest that large, low energy clusters produce graphitic
films, while small, high energy clusters produce films of diamond-like carbon. 相似文献
42.
A bright electroless Ni-P deposition on AM50 magnesium alloy in a sulfate plating bath was proposed by using direct plating process with non-chromate pretreatment. The electroless Ni-P plating on AM50 magnesium alloy has an admirable appearance and good adhesion. The results indicate that the electroless Ni-P deposition with non-chromate pretreatment has better adhesion than that of zinc immersion coating. Anodic polarization curves indicate that the electroless Ni-P deposition obtained from the sulfate bath has similar corrosion-resistance to that obtained from basic nickel carbonate bath. The deposition process generates less pollutant by a non-chromate plating bath and is suitable for the magnesium alloys manufacture because of its low cost. The hardness of the electroless Ni-P plated AM50 is about HV 720.6 and HV 969.7 after heat treatments at 180℃ for 2 h. The wear resistance of Ni-P plated magnesium alloy specimens is about 5 to 9 times as high as that of bare magnesium alloys. 相似文献
43.
简要介绍了国内少有的干气催化部分氧化转化制氢工艺,重点讨论了转化水碳比的控制条件,对降低水碳比操作进行了有益地探讨。 相似文献
44.
Rui Morimoto Chisato Yokomori Akiko Kikkawa Akira Izumi Hideki Matsumura 《Thin solid films》2003,430(1-2):230-235
In this paper, bulk-Si metal–oxide–semiconductor field effect transistors (MOSFETs) are fabricated using the catalytic chemical vapor deposition (Cat-CVD) method as an alternative technology to the conventional high-temperature thermal chemical vapor deposition. Particularly, formation of low-resistivity phosphorus (P)-doped poly-Si films is attempted by using Cat-CVD-deposited amorphous silicon (a-Si) films and successive rapid thermal annealing (RTA) of them. Even after RTA processes, neither peeling nor bubbling are observed, since hydrogen contents in Cat-CVD a-Si films can be as low as 1.1%. Both the crystallization and low resistivity of 0.004 Ω·cm are realized by RTA at 1000 °C for only 5 s. It is also revealed that Cat-CVD SiNx films prepared at 250 °C show excellent oxidation resistance, when the thickness of films is larger than approximately 10 nm for wet O2 oxidation at 1100 °C. It is found that the thickness required to stop oxygen penetration is equivalent to that for thermal CVD SiNx prepared at 750 °C. Finally, complementary MOSFETs (CMOSs) of single-crystalline Si were fabricated by using Cat-CVD poly-Si for gate electrodes and SiNx films for masks of local oxidation of silicon (LOCOS). At 3.3 V operation, less than 1.0 pA μm−1 of OFF leakage current and ON/OFF ratio of 107–108 are realized, i.e. the devices can operate similarly to conventional thermal CVD process. 相似文献
45.
E. V. Chernyshev E. N. Veprov V. A. Petrov S. L. Bogdanov T. Yu. Levina T. I. Petrova V. I. Kashinskii A. A. Zonov A. E. Verkhovskii 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2006,40(1):34-37
Results of a study of tube specimens cut from hot-water boilers show that film-forming octadecyl amine (ODA) used in the process
of preservation removes deposition from the surface of the metal. An ODA film is preserved on the surface after repeated washing
of the latter with hot water. The concentration of chlorides at the surface of the metal after treatment with ODA is lower
than before the treatment.
__________
Translated from élektricheskie Stantsii, No. 11, November 2005, pp. 15–18. 相似文献
46.
本文着重对微波等离子体化学气相沉积法高速沉积的 a-Si∶H 膜的物理性能进行评价研究.测量了沉积膜的光电性能、暗电导激活能、光禁带宽度、光吸收特性、沉积膜中悬键态密度以及氢含量等,并讨论沉积条件对膜性能的影响.结果表明,在沉积速率高达30~90(?)/s 情况下,膜的光电导(光照强度10~5Lux)与暗电导比值可达10~3~10~5,暗电导率从10~(-3)到10~(-11)((?)cm)~(-1),其激活能在0.23~0.88eV 之间(0~200℃温度范围内),光禁带宽度为1.40~2.20eV,氢含量约为2~20%. 相似文献
47.
The fracture stress of chemical vapour deposited diamond 总被引:2,自引:0,他引:2
C. S. J. Pickles 《Diamond and Related Materials》2002,11(12):492-1922
The factors which control the fracture stress of chemical vapour deposited diamond have been studied using the 3-point bend geometry. Fracture stress values of 300–800 MPa for the growth side and 600–1200 MPa for the nucleation side were recorded for samples of thickness 0.4–2.4 mm. A Weibull modulus of 23 was calculated for the growth surface data, showing that the fracture stress variability was low for a brittle material. A theory based on these results demonstrates that the material behaviour is remarkably simple, depending only on the grain size and the sample thickness, regardless of wide variations in other parameters such as optical transmission and stress state. The paper also contains a possible explanation for this well-defined behaviour based on microstress variations resulting from differences in defect density in different growth sectors within a grain. 相似文献
48.
The growth time, growth mode and the method of preparing the supported catalysts play an important role in the growth of single-walled nanotubes (SWNTs). Their effects on the chemical vapor deposition (CVD) growth of SWNTs with MgO-supported catalysts were investigated in this study. It is shown that the growth rate of SWNTs was large during the initial few minutes of growth, however the quality of the tubes was low owing to the formation of many defects. Long term growth may favor the formation of tubes with high quality and high yield, but the introduction of other forms of carbon (impurities) is also unavoidable. There was a balance between the increase in yield and quality and sacrifice of the purity during growth of SWNTs. MgO-supported catalysts prepared by the co-precipitation method were found to be more effective for the synthesis of SWNTs than those prepared by the widely used impregnation method. The size and dispersion state of the catalyst were found to be crucial in enhancing the growth of SWNTs. In addition, growth on the surface of SWNTs over nanosized catalyst films was shown to be more favorable for the synthesis of tube products with higher quality, yield and purity. 相似文献
49.
50.
查健江 《光纤与电缆及其应用技术》2004,1(4):14-19
人们对光纤生产过程中外汽相沉积(OVD)工艺的沉积机理的研究已经有好多年,但实际生产过程中,很多因素都会影响沉积速率和效率。为此我们通过试验,研究了决定沉积速率和沉积效率的主要因素,如预制棒表面温度、SiCl4流量和SiO2颗粒的温度等。 相似文献