全文获取类型
收费全文 | 1330篇 |
免费 | 21篇 |
专业分类
电工技术 | 68篇 |
综合类 | 1篇 |
化学工业 | 312篇 |
金属工艺 | 19篇 |
机械仪表 | 30篇 |
建筑科学 | 19篇 |
矿业工程 | 7篇 |
能源动力 | 21篇 |
轻工业 | 117篇 |
水利工程 | 4篇 |
石油天然气 | 3篇 |
无线电 | 78篇 |
一般工业技术 | 210篇 |
冶金工业 | 356篇 |
原子能技术 | 19篇 |
自动化技术 | 87篇 |
出版年
2023年 | 6篇 |
2022年 | 21篇 |
2021年 | 12篇 |
2020年 | 9篇 |
2019年 | 5篇 |
2018年 | 11篇 |
2017年 | 15篇 |
2016年 | 14篇 |
2015年 | 10篇 |
2014年 | 19篇 |
2013年 | 59篇 |
2012年 | 37篇 |
2011年 | 47篇 |
2010年 | 41篇 |
2009年 | 61篇 |
2008年 | 45篇 |
2007年 | 43篇 |
2006年 | 40篇 |
2005年 | 34篇 |
2004年 | 29篇 |
2003年 | 37篇 |
2002年 | 30篇 |
2001年 | 27篇 |
2000年 | 28篇 |
1999年 | 39篇 |
1998年 | 139篇 |
1997年 | 98篇 |
1996年 | 57篇 |
1995年 | 32篇 |
1994年 | 35篇 |
1993年 | 35篇 |
1992年 | 18篇 |
1991年 | 13篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 9篇 |
1987年 | 17篇 |
1986年 | 11篇 |
1985年 | 16篇 |
1984年 | 13篇 |
1983年 | 9篇 |
1982年 | 19篇 |
1981年 | 12篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1977年 | 11篇 |
1976年 | 22篇 |
1975年 | 5篇 |
1974年 | 5篇 |
排序方式: 共有1351条查询结果,搜索用时 0 毫秒
41.
O Nureki DG Vassylyev M Tateno A Shimada T Nakama S Fukai M Konno TL Hendrickson P Schimmel S Yokoyama 《Canadian Metallurgical Quarterly》1998,280(5363):578-582
High-fidelity transfers of genetic information in the central dogma can be achieved by a reaction called editing. The crystal structure of an enzyme with editing activity in translation is presented here at 2.5 angstroms resolution. The enzyme, isoleucyl-transfer RNA synthetase, activates not only the cognate substrate L-isoleucine but also the minimally distinct L-valine in the first, aminoacylation step. Then, in a second, "editing" step, the synthetase itself rapidly hydrolyzes only the valylated products. For this two-step substrate selection, a "double-sieve" mechanism has already been proposed. The present crystal structures of the synthetase in complexes with L-isoleucine and L-valine demonstrate that the first sieve is on the aminoacylation domain containing the Rossmann fold, whereas the second, editing sieve exists on a globular beta-barrel domain that protrudes from the aminoacylation domain. 相似文献
42.
Y Shimada K Sato E Abe H Kagaya K Ebata M Oba M Sato 《Canadian Metallurgical Quarterly》1996,34(10):615-619
In the Riordan (bridle) transfer, the posterior tibialis muscle as motor is routed through the interosseous membrane and anastomosed into a "bridle" formed by the distal tibialis anterior and peroneus longus muscles. In theory, the bridle provides inversion/eversion balance even if the transfer effects only tenodesis. However, the procedure has been criticized because its insertion is not into bone. This review analyzes the use of bridle transfer in flaccid paresis involving musculature innervated by the peroneal nerve. Surgery was performed 1 to 3 years after injury for patients with traumatic etiology. Ten patients are reviewed at 61 months' mean follow-up. Eight patients had traumatic peroneal nerve loss. Two had neuromuscular etiology. Evaluation included review of records, telephone interviews, and physical examinations. Data on functional status included walking barefoot running, need for bracing, return to duty, and patient satisfaction. Physical examination recorded ankle position and motions, gait findings, and results of static electromyograms. All patients were able to walk barefoot, but 6 of 10 had a mild to moderate limp. Five patients returned to running initially; only two were able to keep running. Nine patients were brace-free initially (polio sequela required bracing initially), and four others returned to bracing. Of these, two experienced an acute "tearing" and dorsiflexion loss, one sustained a prolonged gradual loss of dorsiflexion, and one sustained a contralateral cerebrovascular accident. Only three of seven patients returned to active duty, and one is on jump status. All patients were satisfied with their initial result. Only two patients had no detectable swing phase problems (both returned to active duty). Five patients had peroneal nerve exploration with repair or neurolysis; two of them sustained complete transections. Postoperative electromyograms showed insignificant, if any, nerve return. The Riordan transfer works well for neuromuscular flaccid paresis and in patients with peroneal nerve injuries with low demands. It may stretch out over time to the point of acute failure in patients with high demands. Concurrent peroneal nerve exploration and repair did not seem to be beneficial in this small study. 相似文献
43.
44.
45.
Junichi Takahashi Masahiko Shimada Kouta Iwasaki Hisanori Yaname 《Journal of Electroceramics》2006,17(1):95-98
Single crystals of Bi and Cu-doped Ca3Co2O6were synthesized in a molten K2CO3flux. Using an obtained single crystal of (Ca0.985(5)Bi0.015(5))3(Co0.990(3)Cu0.010(3))2O6elongated to the c-axis direction of the crystal structure, the electric resistivity (ρ) and Seebeck coefficient (S) were measured from room temperature to over 1000 K in air. The single crystal showed p-type semiconducting behavior with ρ values of 1.8 Ω cm at 303 K and 0.017 Ω cm at 1000 K. The S values were +254 μ VK− 1 at 325 K, +360 μ VK− 1 at 420 K, and +214 μ VK− 1 at 1000 K. The power factor (S
2
ρ
− 1) increased with an increase of temperature and attained 2.70 × 10− 4 Wm− 1K− 2 at 1000 K. 相似文献
46.
Uemukai M. Kunoh Y. Shimada N. Suhara T. 《IEEE journal of selected topics in quantum electronics》2003,9(5):1191-1195
An angled-grating distributed Bragg reflector (DBR) laser integrated with a grating outcoupler (GO) is proposed and demonstrated. It consists of an angled broad-area gain stripe surrounded by angled DBR (/spl alpha/-DBR) gratings parallel to the gain stripe and two DBR gratings for feedback at the stripe ends, and a GO for emitting a collimated output beam. Due to distributed Bragg reflection in the /spl alpha/-DBR gratings, filamentation can be suppressed. Single-mode lasing up to 69 mW peak power was obtained under pulse condition. A collimated output beam with divergence angles, close to the diffraction limit, was obtained. These results confirm the effectiveness of the /spl alpha/-DBR gratings. 相似文献
47.
Multidimensional Cube Packing 总被引:1,自引:0,他引:1
Yoshiharu Kohayakawa Flavio Keidi Miyazawa Prabhakar Raghavan Yoshiko Wakabayashi 《Algorithmica》2004,40(3):173-187
We consider the d-dimensional cube packing problem (d-CPP): given a list L of d-dimensional
cubes and (an unlimited quantity of) d-dimensional unit-capacity cubes, called bins, find a packing of L into
the minimum number of bins. We present two approximation algorithms for d-CPP, for fixed d. The first
algorithm has an asymptotic performance bound that can be made arbitrarily close to 2 – (1/2)d . The second
algorithm is an improvement of the first and has an asymptotic performance bound that can be made arbitrarily
close to 2 – (2/3)d . To our knowledge, these results improve the bounds known so far for d = 2 and d = 3, and
are the first results with bounds that are not exponential in the dimension. 相似文献
48.
Makoto Kobayashi Masashi Shimada Yuji Hatano Takuji Oda Brad Merrill Yasuhisa Oya Kenji Okuno 《Fusion Engineering and Design》2013,88(9-10):1749-1752
The deuterium trapping behaviors in tungsten damaged by light ions with lower energy (10 keV C+ and 3 keV He+) or a heavy ion with higher energy (2.8 MeV Fe2+) were compared by means of TDS to understand the effects of cascade collisions on deuterium retention in tungsten. By light ion irradiation, most of deuterium was trapped by vacancies, whose retention was almost saturated at the damage level of 0.2 dpa. For the heavy ion irradiation, the deuterium trapping by voids was found, indicating that cascade collisions by the heavy ion irradiation would create the voids in tungsten. Most of deuterium trapped by the voids was desorbed in higher temperature region compared to that trapped by vacancies. It was also found that deuterium could accumulate in the voids, resulting in the formation of blisters in tungsten. 相似文献
49.
We report on preparation and properties of anatase Nb-doped TiO2 transparent conducting oxide films on glass and polyimide substrates. Amorphous Ti0.96Nb0.04O2 films were deposited at room temperature by using sputtering, and were then crystallized through annealing under reducing atmosphere. Use of a seed layer substantially improved the crystallinity and resistivity (ρ) of the films. We attained ρ = 9.2 × 10− 4 Ω cm and transmittance of ~ 70% in the visible region on glass by annealing at 300 °C in vacuum. The minimum ρ of 7.0 × 10− 4 Ω cm was obtained by 400 °C annealing in pure H2. 相似文献
50.
Atsushi Kawase Momoko Hatanaka Naoya Matsuda Hiroaki Shimada Masahiro Iwaki 《International journal of molecular sciences》2022,23(15)
SLC25A39/40, involved in mitochondrial GSH (mGSH) import from the cytoplasm, is essential for protection against oxidative stress and mitochondrial dysfunction. We examined the effects of cholestasis, through bile duct ligation (BDL) and lipopolysaccharide (LPS)-induced inflammation in mice, on Slc25a39/40 expression. Additionally, we used human clear cell renal carcinoma (KMRC-1) cells to elucidate the mechanism of regulation of SLC25A39/40 expression in the kidneys after LPS treatment. BDL resulted in a decrease in Slc25a39 mRNA in the liver and a decrease in Slc25a39/40 mRNA and protein in the kidneys. Consequently, there was a significant decrease in mGSH levels in the kidneys of BDL mice compared with those in sham mice. LPS treatment resulted in increased Slc25a40 expression in the kidneys. In KMRC-1 cells, the combination treatment of LPS-RS or FPS-ZM1 with LPS suppressed the LPS-induced increase in SLC25A40, suggesting that SLC25A40 expression could be regulated by the signaling pathway via toll-like receptor 4 and the receptor for advanced glycation end products, respectively. Our findings contribute to understanding the role of mGSH in the maintenance of the mitochondrial redox state. To the best of our knowledge, this is the first study that demonstrates the changes in Slc25a39/40 expression in mice with cholestasis-associated renal injury and LPS-induced inflammation. 相似文献