全文获取类型
收费全文 | 4547篇 |
免费 | 160篇 |
国内免费 | 23篇 |
专业分类
电工技术 | 286篇 |
综合类 | 15篇 |
化学工业 | 1426篇 |
金属工艺 | 135篇 |
机械仪表 | 138篇 |
建筑科学 | 122篇 |
矿业工程 | 5篇 |
能源动力 | 209篇 |
轻工业 | 406篇 |
水利工程 | 18篇 |
石油天然气 | 6篇 |
无线电 | 309篇 |
一般工业技术 | 991篇 |
冶金工业 | 136篇 |
原子能技术 | 129篇 |
自动化技术 | 399篇 |
出版年
2023年 | 33篇 |
2022年 | 50篇 |
2021年 | 128篇 |
2020年 | 60篇 |
2019年 | 74篇 |
2018年 | 85篇 |
2017年 | 66篇 |
2016年 | 114篇 |
2015年 | 88篇 |
2014年 | 128篇 |
2013年 | 255篇 |
2012年 | 254篇 |
2011年 | 292篇 |
2010年 | 244篇 |
2009年 | 266篇 |
2008年 | 291篇 |
2007年 | 227篇 |
2006年 | 216篇 |
2005年 | 142篇 |
2004年 | 152篇 |
2003年 | 172篇 |
2002年 | 149篇 |
2001年 | 80篇 |
2000年 | 85篇 |
1999年 | 68篇 |
1998年 | 90篇 |
1997年 | 73篇 |
1996年 | 66篇 |
1995年 | 60篇 |
1994年 | 54篇 |
1993年 | 61篇 |
1992年 | 55篇 |
1991年 | 56篇 |
1990年 | 38篇 |
1989年 | 55篇 |
1988年 | 20篇 |
1987年 | 44篇 |
1986年 | 33篇 |
1985年 | 42篇 |
1984年 | 27篇 |
1983年 | 33篇 |
1982年 | 32篇 |
1981年 | 29篇 |
1980年 | 19篇 |
1979年 | 26篇 |
1978年 | 24篇 |
1977年 | 18篇 |
1976年 | 12篇 |
1975年 | 11篇 |
1973年 | 9篇 |
排序方式: 共有4730条查询结果,搜索用时 0 毫秒
951.
Shinobu Yoshimura Genki Yagawa Chang-Ryul Pyo Koichi Kashima Takashi Shimakawa Shigeru Takamatsu 《International Journal of Pressure Vessels and Piping》1995,63(3):293-302
This paper describes some simplified stable crack growth analyses of two kinds of inhomogeneous CT specimens. The one is machined from a submerged are welded plate of a nuclear pressure vessel A533B Class 1 steel, while the other is machined from an electron-beam welded plate of the A533B Class 1 steel and a high strength HT80 steel. In both specimens, initial cracks are placed to be normal to the fusion line. The ratio of yield stresses of the weld metal and the base metal of the A533B Class 1 steel is about 1·15, while that of the HT80 and the A533B Class 1 steels is about 1·4.
The generation phase crack growth analyses using the GE/EPRI and the reference stress methods are performed, calculating an applied load (P) and the J-value, while the application phase analyses of analyses using the R6 method are performed to calculate the maximum value of the applied load (Pmax). Finally, some modification procedures of the three simplified estimation schemes are discussed in order to apply them to inhomogeneous material regimes. 相似文献
952.
Because of their unique structures and properties, π-conjugated polymers have attracted the attention of scientists and engineers. The authors have studied the synthesis of two kinds of π-conjugated poly(aromatic acetylene)s, i.e. poly(arylacetylene)s and poly(aryleneethynylene)s with the aim of obtaining new polymers having novel functions or higher performances. This review mainly concerns the authors' results, as follows: first, we describe the synthesis and properties of achiral poly(arylacetylene)s, containing trimethylsilyl groups, oligodimethylsiloxanyl groups, dendritic groups, and glavinoxyl groups, for application as oxygen permselective membrane materials. Their self-membrane-forming abilities and high oxygen permeabilities are presented. Second, the synthesis by asymmetric-induced polymerization of chiral poly(arylacetylene)s having both a main-chain chirality and chiral pendant groups and their application as optical resolution membranes are described. Third, two new synthetic methods for preparing chiral helical poly(phenylacetylene)s without the coexistence of any other chiral moieties are presented. One is helix-sense-selective addition polymerization and the other is in situ removal of chiral pendant groups from membranes of poly(arylacetylene)s that also contain a main-chain chirality. The chiral helical poly(arylacetylene)s were tested as optical resolution membranes. The chiral and achiral poly(arylacetylene)s were synthesized by addition polymerization using metathesis catalysts or rhodium complexes. Finally, the synthesis of regiospecific poly(aryleneethynylene)s bearing stable radicals by the polycondensation of bromoethynylanthracene derivatives using a Pd(0) complex is described. The magnetization and the static magnetic susceptibility of the polyradicals are explained. 相似文献
953.
Ryu Komatsu Ryo Nakazato Takeru Sasaki Akio Suzuki Naoyuki Senda Takuya Kawata Yasuhiro Jimbo Tomoya Aoyama Naoto Ohno Susumu Kawashima Hisao Ikeda Shingo Eguchi Yoshiharu Hirakata Shunpei Yamazaki Takashi Shiraishi Seiji Yasumoto Masataka Nakada Masataka Sato Chris Bower Darryl Cotton Andrew Matthews Piers Andrew Catalin Gheorghiu Johan Bergquist 《Journal of the Society for Information Display》2015,23(2):41-49
In this study, a 5.9‐inch foldable active‐matrix organic light emitting diode (AMOLED) display was developed. A folding test was performed repeatedly. The display survived the folding test (100,000 folds) with a curvature radius of 2 mm. To protect an organic light emitting diode (OLED) against moisture, inorganic passivation layers are provided on the upper and lower sides of the flexible display. Using our transfer technology, high density passivation layers can be obtained. The measured water vapor transmission rate of the layer is 7 × 10?6 g/m2?day or less, which improves OLED reliability. With these techniques, we have developed a book‐type display, which is repeatedly foldable like a book, and a tri‐fold display including a display area, which is foldable in three. 相似文献
954.
Hikojiro Saitoh Takashi Takata Hiromasa Nikai Hideaki Shintani Suong-Hyu Hyon Yoshito Ikada 《Journal of materials science. Materials in medicine》1994,5(4):194-199
This study was undertaken to examine the osseous tissue compatibility of polylactic acid (PLA) with properties of bioabsorbability and plasticity. Two kinds of granular PLA with different molecular weight (PLA-H: 28 000 MW, PLA-L: 10 600 MW) were implanted into rat tibiae and light microscopic sections were prepared at 1, 2, 4, 8, 16, and 24 weeks following surgery. The tissue compatibility of the PLAs was compared with that of hydroxyapatite (HAP) which is a non-absorbable biocompatible material. After implantation, both PLAs were gradually absorbed and replaced by marrow tissue at 24 weeks. PLA-H degraded slower than PLA-L. New bone formation was observed around each PLA by 4 weeks, and a vast amount of bone deposited on PLA-H at 16 weeks. Phagocytic reactions to the PLAs were noted, however, severe inflammation was not seen. HAP was not absorbed and bone surrounded it throughout the experiment. These results indicate good tissue compatibility of PLA as a bioabsorbable material at the skeletal site. 相似文献
955.
Yoshitsugu Kojima Takashi Ohta Mitsumasa Matsushita Minoru Takahara Toshio Kurauchi 《Polymer Engineering and Science》1992,32(10):686-689
Flat packages (FPs) were formed from epoxy molding compounds with various physical properties using a transfer molding machine. The compounds were prepared by changing kinds and amounts of additives and addition methods. The thermal shock test was carried out by the following procedures. The plastic package was soaked alternately in liquid nitrogen (?196°) and in liquid solder (200°) in the cycle of 140s. The median life to crack initiation was defined to be the cycles when half of the specimens exhibited crack initiation. According to linear fracture mechanics, the following expression was obtained relating the median life N, thermal stress σt, and strength σb; N = C/σ·(σb/σt)m. We found the linear relation between logarithm of Nσ and logarithm of σb/σt for various packages, and estimated the values of C and m as 5 × 104 MPa2 and 5.5, respectively. The value of m was the same as that obtained for a dual-in-line package. 相似文献
956.
This paper describes external reference management and distributed unification in a distributed implementation of a concurrent logic programming language KL1. This implementation is based on the KLIC system. KLIC has a feature calledgeneric objects that enable easy modification and extension of the system without changes in the core implementation. This distributed implementation is built upon the same core and external references are represented using generic objects. Unification operations are defined as methods of generic objects. Since creation of interprocessor reference loops cannot be avoided, we studied a new unification scheme that can cope with interprocessor reference loops. We built several experimental distributed systems that all demonstrate reasonable efficiency. 相似文献
957.
958.
Crystallization Behavior of Molecular Compound in Binary Mixture System of 1,3‐Dioleoyl‐2‐Palmitoyl‐sn‐Glycerol and 1,3‐Dipalmitoyl‐2‐Oleoyl‐sn‐Glycerol 下载免费PDF全文
Kengoh Nakanishi Yumi Mikiya Takashi Ishiguro Satoru Ueno 《Journal of the American Oil Chemists' Society》2018,95(1):51-59
Previous studies showed that the stable β‐form of molecular compound (MC) crystals having a double‐chain‐length structure is formed in a binary mixture system of 1,3‐dioleoyl‐2‐palmitoyl‐sn‐glycerol (OPO) and 1,3‐dipalmitoyl‐2‐oleoyl‐sn‐glycerol (POP) with a 1:1 concentration ratio of OPO and POP. The use of MC crystals made of POP and OPO for edible applications, such as margarine, is advantageous due to no‐trans, low‐saturated, and high‐oleic fats. Industrial manufacturing technology involves rapid cooling processes, and the kinetic properties of crystallization of MC of OPO and POP are required. In this study, we clarified the crystallization of MC of OPO and POP under rapid cooling at rates of 1–150 °C min?1, using synchrotron radiation time‐resolved X‐ray diffraction and differential scanning calorimetry methods. The main results are as follows: (1) POP and OPO crystallized in separate manners without the formation of MC crystals under rapid cooling (>40 °C min?1), while MC crystals started to form with decreasing rates of cooling in addition to the POP and OPO crystals (<30 °C min?1); (2) metastable and stable forms sub‐α, α, β′, and β of POP and OPO were formed, whereas the MC crystals of β were formed during the cooling processes; and (3) the heating processes after crystallization by rapid cooling caused separate melting of the metastable and stable forms of POP and OPO crystals and the formation of MC crystals of β made of POP and OPO, as well as melting of the MC crystals alone. 相似文献
959.
Ryo Hashikawa Yasuhiro Fujii Atsushi Kinomura Takeshi Saito Arifumi Okada Takashi Wakasugi Kohei Kadono 《Journal of the American Ceramic Society》2019,102(4):1642-1651
Radiophotoluminescence phenomena have been widely investigated on various types of materials for dosimetry applications. We report that an aluminoborosilicate glass containing 0.005 mol% copper exhibits intense photoluminescence in the visible region induced by X-ray and γ-ray irradiation. The luminescence is assigned to the 3d94s1 → 3d10 transition of Cu+. The proportionality of the intensity of the induced photoluminescence to the irradiation dose was confirmed up to 0.5 kGy using 60Co γ-ray irradiation. Based on the spectroscopic results, a potential mechanism was proposed for the enhancement of the photoluminescence. The exposure to the ionizing radiation generates electron-hole pairs in the glass, and the electrons are subsequently captured by the Cu2+ ions, which are converted to Cu+ and emit the luminescence. For the glass containing 0.01 mol% copper, the pronounced enhancement of the photoluminescence was not observed because the reverse reaction, ie, the capture of the holes by the Cu+ ions, becomes prominent. The photoluminescence induced by the irradiation was stably observed for the glasses kept at room temperature and even for the glasses heat-treated at 150°C. However, the induced photoluminescence could be eliminated by the heat treatment at a temperature at 500°C, and the glass returned to the initial pre-irradiation state. The Cu-doped aluminoborosilicate glass is a potential candidate for use in dosimetry applications. 相似文献
960.
Rong Tu Jiaojiao Li Mingpu Jia Qizhong Li Meijun Yang Song Zhang Takashi Goto 《International Journal of Applied Ceramic Technology》2023,20(3):1919-1927
B4C–CrB2 composites were prepared by arc-melting using B4C and CrB2 powders as raw materials. The eutectic composition of B4C–CrB2 system was 30B4C–70CrB2 (mol%) with a labyrinth-like irregularly layered eutectic microstructure, composed of B4C phase about 1–2 μm in thickness dispersing in CrB2 matrix, much smaller than raw powders. The interface of the eutectic composite was well bonded, and there were edge dislocations at the interface to alleviate the interface mismatch. The eutectic temperature of B4C–CrB2 composites was approximately 2200 K. At the eutectic composition, the B4C–CrB2 composites showed the maximum Vickers hardness (24.6 GPa) and fracture toughness (4.3 MPa m1/2) at room temperature. 相似文献