全文获取类型
收费全文 | 2859篇 |
免费 | 53篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 82篇 |
综合类 | 3篇 |
化学工业 | 496篇 |
金属工艺 | 86篇 |
机械仪表 | 49篇 |
建筑科学 | 57篇 |
能源动力 | 77篇 |
轻工业 | 196篇 |
水利工程 | 7篇 |
石油天然气 | 4篇 |
无线电 | 372篇 |
一般工业技术 | 403篇 |
冶金工业 | 860篇 |
原子能技术 | 66篇 |
自动化技术 | 159篇 |
出版年
2022年 | 9篇 |
2021年 | 40篇 |
2020年 | 23篇 |
2019年 | 18篇 |
2018年 | 33篇 |
2017年 | 18篇 |
2016年 | 29篇 |
2015年 | 27篇 |
2014年 | 52篇 |
2013年 | 132篇 |
2012年 | 79篇 |
2011年 | 88篇 |
2010年 | 80篇 |
2009年 | 69篇 |
2008年 | 104篇 |
2007年 | 80篇 |
2006年 | 73篇 |
2005年 | 77篇 |
2004年 | 83篇 |
2003年 | 66篇 |
2002年 | 66篇 |
2001年 | 60篇 |
2000年 | 62篇 |
1999年 | 73篇 |
1998年 | 301篇 |
1997年 | 221篇 |
1996年 | 138篇 |
1995年 | 92篇 |
1994年 | 83篇 |
1993年 | 86篇 |
1992年 | 45篇 |
1991年 | 39篇 |
1990年 | 45篇 |
1989年 | 31篇 |
1988年 | 28篇 |
1987年 | 33篇 |
1986年 | 21篇 |
1985年 | 31篇 |
1984年 | 37篇 |
1983年 | 24篇 |
1982年 | 28篇 |
1981年 | 33篇 |
1980年 | 28篇 |
1979年 | 23篇 |
1978年 | 17篇 |
1977年 | 15篇 |
1976年 | 31篇 |
1975年 | 8篇 |
1974年 | 6篇 |
1972年 | 7篇 |
排序方式: 共有2917条查询结果,搜索用时 15 毫秒
51.
T Yamamura H Matsuzaki K Seo M Kimura T Shinagawa 《Canadian Metallurgical Quarterly》1998,28(11):1175-1178
We report herein the case of a 59-year-old woman who developed a local recurrence of rectal cancer which showed extremely rapid growth. The patient had undergone a curative low anterior resection with total mesoexcision, and was discharged on postoperative day 25 after an uneventful recovery. However, 2 months after the operation, she developed bleeding from the rectum during defecation, the quantity of which gradually increased. A colonoscopy performed during the fifth postoperative month revealed a circular tumor at the suture line. The tumor was unresectable because it had firmly invaded not only the sacrum, but also the right ureter. Despite the administration of 5-fluorouracil and leucovorin, the patient died of cancer 18 months after her initial surgery. Considering that local recurrence of rectal cancer does not usually occur within 1 year after surgery, this case is unusual because the local recurrence developed very early and showed extremely rapid growth, occupying the entire lumen of the rectum by the time it was detected by colonoscopy during the fifth postoperative month. 相似文献
52.
Experimental demonstration of soliton data transmission over unlimited distances with soliton control in time and frequency domains 总被引:1,自引:0,他引:1
Nkazawa M. Suzuki K. Yamada E. Kubota H. Kimura Y. Takaya M. 《Electronics letters》1993,29(9):729-730
A 2/sup 9/-1 pseudorandom-binary-sequence soliton signal has been transmitted experimentally over one million km for the first time with no degradation in the bit error rates. The synchronous modulator was driven by a timing clock signal extracted from the transmitting data signal. These results mean that it is possible to send soliton data signals over unlimited distances through the use of soliton control in the time and frequency domains.<> 相似文献
53.
Rod-shaped BaTiO3 powder particles have been prepared from rod-shaped TiO2 ·nH2O and BaCO3 in molten chloride. The morphology of BaTiO3 particles was studied referring to the effects of the chemical species of the starting titanium compound, amount of chloride, particle size of the titanium compound and reaction conditions, and the preparation condition of rod-shaped BaTiO3 has been determined: i.e., large TiO2 ·nH2O particles were heated at 700°C in molten salt with an equal amount of BaTiO3. This condition was effective in suppressing the formation of BaTiO3 by a solution-precipitation process as well as the deformation of either TiO2 ·nH2O or BaTiO3, which are responsible for the formation of equiaxed BaTiO3 particles. The obtained rod-shaped BaTiO3 particles had a cubic symmetry. Electron diffraction analysis showed that the following topotactic relation is retained; 0 1 0potassium tetratitanate 0 1 0hydrated titania 1 0 0anatase 1 0 0barium titanate 相似文献
54.
Modified quadratic discriminant functions and the application to chinese character recognition 总被引:8,自引:0,他引:8
Kimura F Takashina K Tsuruoka S Miyake Y 《IEEE transactions on pattern analysis and machine intelligence》1987,(1):149-153
Issues in the quadratic discriminant functions (QDF) are discussed and two types of modified quadratic disriminant functions (MQDF1, MQDF2) which are less sensitive to the estimation error of the covariance matrices are proposed. The MQDF1 is a function which employs a kind of a (pseudo) Bayesian estimate of the covariance matrix instead of the maximum likelihood estimate ordinarily used in the QDF. The MQDF2 is a variation of the MQDF1 to save the required computation time and storage. Two discriminant functions were applied to Chinese character recognition to evaluate their effectiveness, and remarkable improvement was observed in their performance. 相似文献
55.
Knowledge based approach is effective for renovating design and manufacturing processes. The objective of this paper is to investigate roles and usages of expert engineering knowledge in high-quality manufacturing, and to study a practical knowledge capturing method for realizing engineering support tools. An engineer oriented interface for a capturing method is proposed, and a flexible representation framework is studied for various types of expert knowledge. An integrated knowledge-based system has been developed for mold design support. The results have been evaluated by design and manufacturing of molds for cellular phones, and have shown substantial reduction of lead time for mold production. 相似文献
56.
Yttria (Y2O3) films were prepared at high deposition rates of up to 83 nm/s (300 μm/h) by laser chemical vapor deposition (LCVD) using an Y(dpm)3 precursor. The effects of deposition conditions, mainly total gas pressure and laser power, on morphology, deposition rate and preferred orientation were studied. Plasma was produced around the substrate over a critical laser power resulting in significant increases in deposition temperature and deposition rate. The high deposition rate (300 μm/h) by LCVD was about 100 to 1000 times as high as those by conventional CVD. The morphology of Y2O3 films changed from faceted and columnar structures with high (400) orientation to a columnar structure with high (440) orientation, and finally to a cone-like structure with moderate (440) orientation with increasing total gas pressure (Ptot). 相似文献
57.
Copoly(amide-ethers) containing two types of tertiary amine units were made as antistatic modifiers for poly(ethylene terephthalate) (PET) fibers. The filaments of the copolymers were melt-spun and reacted with three alkylating agents in order to quaternize the tertiary amine into a sulfo-betaine, a carbobetaine, and an ammonium ion. The apparent electric resistivity of the filaments was greatly reduced by this reaction, being in the range of 106 to 108 Ω/cm. However, because these quaternized copolymers incurred decomposition during blend spinning with PET, a blend PET fiber containing one type of copoly(amide-ether) was melt-spun and subjected to quaternization of the amino groups as well as to surface crosslinking with various alkylating and epoxy agents. The quaternized blend fibers obtained showed improved antistatic properties compared with the original blend fiber. Particularly, the fibers crosslinked with epoxy compounds were found to have the best antistatic properties that had ever been attained with this type of modification. The antistatic properties were retained even after dyeing, because both hydrophilic and ionic groups had been effectively immobilized on the surface. Since this quaternization and crosslinking could be conducted on-line with spinning and drawing within a short reaction time, this modification technique is called “spin-finishing method”, which should be superior to the conventional methods in terms of cost performance and productivity. 相似文献
58.
Toshio Kimura Toru Takahashi Toshihiko Tani Yasuyoshi Saito 《Journal of the American Ceramic Society》2004,87(8):1424-1429
Bi0.5 Na0.5 TiO3 (BNT) and 0.94Bi0.5 Na0.5 TiO3 ·0.06BaTiO3 (BNT–BT) bulk ceramics with extensive 〈100〉 texture were prepared by the reactive-templated grain growth method, using platelike Bi4 Ti3 O12 (BIT) particles as templates for BNT. Calcined compacts were composed of matrix grains with random orientation and 〈100〉-oriented grains transformed from aligned BIT particles, and the texture developed by the growth of oriented grains during sintering. Ceramics with extensive texture were obtained by using the starting mixture containing the maximum concentration of platelike BIT to form the maximum volume fraction of oriented grains. 相似文献
59.
The effect of particle agglomeration on sintering has been studied by slipcasting suspensions with pH values ranging from 2 to 11. The rate of densification has been found to depend on the degree of agglomeration. Complete dispersion of alumina primary particles has not been attained through adjustment of pH of suspensions, and agglomerates also remained in the best-dispersed suspension. Elimination of the agglomerates by sedimentation lowered the densification temperature of slip-cast compacts. The grain size-density curve is a function of temperature. High-density and small-grained sintered bodies were obtained by low-temperature long-time firing. 相似文献
60.
Jared Bon Christan Grant Josh Imbriani Erik Holbrook 《International Journal of Software and Informatics》2016,10(3)
In this paper, we describe our progress in creating the framework for an
interactive application that allows humans to actively participate in a t-SNE clustering
process. t-SNE (t-Distributed Stochastic Neighbor Embedding) is a dimensionality
reduction technique that maps high dimensional data sets to lower dimensions that can
then be visualized for human interpretation. By prompting users to monitor outlying
points during the t-SNE clustering process, we hypothesize that users may be able to make
clustering faster and more accurate than purely algorithmic methods. Further research
would test these hypotheses directly. We would also attempt to decrease the lag time
between the various components of our application and develop an intuitive approach for
humans to aid in clustering unlabeled data. Research into human assisted clustering can
combine the strengths of both humans and computer programs to improve the results of
data analysis. 相似文献