全文获取类型
收费全文 | 1954篇 |
免费 | 48篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 166篇 |
综合类 | 3篇 |
化学工业 | 391篇 |
金属工艺 | 105篇 |
机械仪表 | 35篇 |
建筑科学 | 17篇 |
矿业工程 | 2篇 |
能源动力 | 45篇 |
轻工业 | 133篇 |
水利工程 | 3篇 |
石油天然气 | 9篇 |
无线电 | 192篇 |
一般工业技术 | 350篇 |
冶金工业 | 395篇 |
原子能技术 | 37篇 |
自动化技术 | 122篇 |
出版年
2023年 | 6篇 |
2022年 | 14篇 |
2021年 | 25篇 |
2020年 | 16篇 |
2019年 | 19篇 |
2018年 | 16篇 |
2017年 | 20篇 |
2016年 | 35篇 |
2015年 | 29篇 |
2014年 | 37篇 |
2013年 | 95篇 |
2012年 | 75篇 |
2011年 | 82篇 |
2010年 | 86篇 |
2009年 | 83篇 |
2008年 | 79篇 |
2007年 | 86篇 |
2006年 | 58篇 |
2005年 | 55篇 |
2004年 | 42篇 |
2003年 | 48篇 |
2002年 | 53篇 |
2001年 | 41篇 |
2000年 | 41篇 |
1999年 | 43篇 |
1998年 | 159篇 |
1997年 | 112篇 |
1996年 | 82篇 |
1995年 | 60篇 |
1994年 | 62篇 |
1993年 | 59篇 |
1992年 | 24篇 |
1991年 | 15篇 |
1990年 | 15篇 |
1989年 | 26篇 |
1988年 | 15篇 |
1987年 | 13篇 |
1986年 | 15篇 |
1985年 | 18篇 |
1984年 | 16篇 |
1983年 | 14篇 |
1982年 | 17篇 |
1981年 | 10篇 |
1980年 | 18篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1976年 | 14篇 |
1975年 | 5篇 |
1974年 | 7篇 |
1973年 | 7篇 |
排序方式: 共有2005条查询结果,搜索用时 31 毫秒
91.
Kurita H. Shimizu T. Yokoyama H. 《IEEE journal of selected topics in quantum electronics》1996,2(3):508-513
We investigated the detailed characteristics of synchronization of mode-locked laser diodes (MLLD's) by subharmonic optical pulse injection. It was shown that optical harmonic injection mode-locking was not very sensitive to injection pulse shapes. In the time domain, subharmonic injection pulses were multiplexed inside the MLLD and these multiplexed pulses effectively modulated the absorbance of the saturable absorber at the MLLD's repetition frequency. It was also found in the spectral domain that injection pulse trains should have optical spectrum components broader than the MLLD's intermode spacing, and injection spectral components should couple to at least two modes of the MLLD 相似文献
92.
93.
H Sentsui R Takami T Nishimori K Murakami T Yokoyama Y Yokomizo 《Canadian Metallurgical Quarterly》1998,60(12):1329-1333
PURPOSE: Lamotrigine (LTG) is recognised as effective add-on therapy for focal epilepsies, but this is the first double-blind, placebo-controlled, crossover study in treatment-resistant generalised epilepsy. METHODS: The study consisted of 2 x 8-week treatment periods followed by a 4-week washout period. Patients received doses of either 75 or 150 mg daily, depending on their concomitant antiepileptic drugs (AEDs). Long-term continuation was offered at the end of the study with open-label LTG. RESULTS: Five centres in Australia recruited 26 patients who were having absence, myoclonic, or generalized tonic-clonic seizures or a combination of these. Twenty-two patients completed the study. There was a significant reduction in frequency of both tonic-clonic and absence seizure types with LTG. A 350% decrease in seizures was observed for tonic-clonic seizures in 50% of cases and for absence seizures in 33% of evaluable cases. Rash was the only adverse effect causing discontinuation. Twenty-three of 26 opted for open-label LTG, with 20 still receiving LTG for a mean of 26 months. In these 20, 80% had > or =50% seizure reduction and five (25%) were seizure free. CONCLUSIONS: This study shows that LTG is effective add-on therapy in patients with refractory generalised epilepsies. Statistically significant reduction in seizures in both absence and tonic-clonic seizure types was seen even with low doses of LTG. 相似文献
94.
T Okamura S Yokoyama E Kou N Inoue T Kuriyama A Matsumuro H Fujita T Tanaka K Miyao 《Canadian Metallurgical Quarterly》1998,51(10):845-848
A 57-year-old man was admitted to our hospital because of restenosis of the left main coronary trunk (LMT) after patch angioplasty for the LMT lesion. PTCA was repeated four times during three years after patch angioplasty, but recent coronary angiogram still demonstrated 75% restenosis of the LMT lesion. Double-CABG was performed to LAD and LCX using the left internal thoracic artery and saphenous vein graft. Postoperative coronary angiogram revealed an excellent result. A careful consideration must be given to the indication of the patch angioplasty of the LMT lesion. 相似文献
95.
96.
Z Shen M Mohiuddin H Yokoyama GR Reiss VJ DiSesa 《Canadian Metallurgical Quarterly》1996,112(5):1315-1318
Indefinite donor-specific tolerance to a cardiac allograft can be induced through pretransplantation intrathymic injection of donor spleen cells and a single intraperitoneal injection of antilymphocyte serum. This study was designed to determine whether this phenomenon was reproducible with grafts differing in either class I major histocompatibility complex only or class II MHC only. Donors of cells and hearts in all experiments were RP rats. Class I MHC disparate grafts were performed by placing an RP heart into a Lewis recipient, and class II disparate grafts were performed with RP donors and Wistar Furth recipients. Lewis (n = 10) and Wistar Furth (n = 10) recipients underwent intraperitoneal injection of 1 ml antilympocyte serum and intrathymic injection of 5 x 10(7) RP spleen cells. Three weeks later, heterotopic cardiac transplantation was done with a heart from an RP rat. Control rats had no pretreatment or received antilympocyte serum alone. Without pretreatment, RP hearts survived 7 to 9 days (mean 8 days) in Lewis recipients (n = 5) and 9 to 14 days (mean 12 days) in Wistar Furth recipients (n = 5). Antilymphocyte serum alone produced slight prolongation of graft survival. Lewis rats pretreated with class I disparate RP splenocytes and antilympocyte serum had graft survivals of 8 to 27 days (mean 14 days), not significantly different from the results with antilympocyte serum alone. Class II disparate RP grafts placed in pretreated Wistar Furth rats had significant prolongation of graft survival, with four of five grafts surviving longer than 60 days (p < 0.01 vs antilympocyte serum alone). These results suggest that a disparity at the class II locus of the major histocompatibility complex is critical for the induction of cardiac allograft tolerance after intrathymic inoculation of allogeneic cells. 相似文献
97.
Troxel D. Schreiber W. Bishop R. Buckley R. Bunza G. Eguchi T. Goldwasser S. Jakubson J. Jung-Shu Kung Ng D. Takemoto S. Yokoyama E. 《Communications, IEEE Transactions on》1981,29(12):1841-1848
The two-channel system previously reported has been implemented in hardware using system parameters appropriate to consumer television. The basic system divides the spectrum into lowand high-frequency spatial components. The lows are coarsely sampled and finely quantized and the highs finely sampled and coarsely quantized using a companded, randomized quantizer. The purpose of this experiment was to demonstrate the potential of the system for low-cost practical application, to study the effect of the character of the randomizing noise, and to ascertain that there were no deleterious effects due to interlace, motion, or input noise. Theoretical noise calculations were qualitatively confirmed. 相似文献
98.
Kino K Murakami-Nitta T Oishi M Ishiguro S Kirimura K 《Journal of Bioscience and Bioengineering》2004,97(1):82-84
With the objective of developing an odorless biodegradation process for dimethyl sulfoxide (DMSO), Hyphomicrobium sp. WU-OM3 was isolated. During the cultivation of strain WU-OM3 cells with 20 mM dimethyl sulfone (DMSO2) as the sole carbon source, DMSO2 was completely consumed within 48 h and sulfate ion accumulated in the culture broth. Methanesulfonate was also detected as an intermediate of DMSO2 degradation. By combining the DMSO-oxidizing microorganism and strain WU-OM3 cells, 0.64 mM (50 mg/l) DMSO was degraded to sulfate ion with 80% molar conversion ratio. 相似文献
99.
The purpose of this research was to investigate the ice growth of a single crystal in three dimensions. Three-dimensional pattern of ice crystal growth in supercooled water was observed using Mach–Zehnder spectro-interferometer. Temperature was varied from −0.3 to −1.6 °C. It was found that the ice crystal began to grow as a single crystal at the tip of the capillary tube and propagated freely in supercooled water. Time variation of the shape of dendrite on a–c plane was obtained. It was found that half parabola fits the shape very closely, and the coefficient of squared term, a, of a quadratic function was calculated. The coefficient, a varied in time but at quasi steady state it was found to be depending mostly upon the degree of supercooling. Furthermore, the growth velocity in c-axis at the flat surface was calculated from the thickness measured. It was found that the velocity in c-axis is independent of the degree of supercooling but depends upon time, in other words, the thickness in c-axis. 相似文献
100.