全文获取类型
收费全文 | 1923篇 |
免费 | 31篇 |
专业分类
电工技术 | 17篇 |
综合类 | 3篇 |
化学工业 | 151篇 |
金属工艺 | 15篇 |
机械仪表 | 57篇 |
建筑科学 | 42篇 |
能源动力 | 46篇 |
轻工业 | 64篇 |
水利工程 | 10篇 |
无线电 | 152篇 |
一般工业技术 | 222篇 |
冶金工业 | 986篇 |
原子能技术 | 4篇 |
自动化技术 | 185篇 |
出版年
2023年 | 4篇 |
2022年 | 9篇 |
2021年 | 19篇 |
2020年 | 24篇 |
2019年 | 19篇 |
2018年 | 18篇 |
2017年 | 30篇 |
2016年 | 29篇 |
2015年 | 17篇 |
2014年 | 20篇 |
2013年 | 70篇 |
2012年 | 41篇 |
2011年 | 67篇 |
2010年 | 44篇 |
2009年 | 36篇 |
2008年 | 48篇 |
2007年 | 47篇 |
2006年 | 47篇 |
2005年 | 46篇 |
2004年 | 39篇 |
2003年 | 41篇 |
2002年 | 30篇 |
2001年 | 18篇 |
2000年 | 17篇 |
1999年 | 58篇 |
1998年 | 309篇 |
1997年 | 178篇 |
1996年 | 117篇 |
1995年 | 69篇 |
1994年 | 57篇 |
1993年 | 68篇 |
1992年 | 16篇 |
1991年 | 28篇 |
1990年 | 13篇 |
1989年 | 26篇 |
1988年 | 22篇 |
1987年 | 35篇 |
1986年 | 23篇 |
1985年 | 28篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 3篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1978年 | 5篇 |
1977年 | 27篇 |
1976年 | 44篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1973年 | 2篇 |
排序方式: 共有1954条查询结果,搜索用时 31 毫秒
1.
Husain Syed Sameed Ong Eng-Jon Bober Miroslaw 《International Journal of Computer Vision》2021,129(5):1432-1450
International Journal of Computer Vision - We propose a novel CNN architecture called ACTNET for robust instance image retrieval from large-scale datasets. Our key innovation is a learnable... 相似文献
2.
OBJECTIVE: To examine the relationship between pregnancy incidence and the level of serum E2 during danazol therapy. DESIGN: Danazol was given by 200 mg four times daily for 3 months. Serum E2 level was checked after completing the therapy, but before stopping medication. Patients then were advised to conceive at the appropriate time over a 6-month period. SETTING: Reproductive and Endocrine Laboratory of the Department of Obstetrics and Gynecology, Keelung Chang Gung Memorial Hospital, Keelung, Taiwan. PATIENTS: Infertile women with invasive endometriosis receiving conservative surgery and danazol treatment. INTERVENTIONS: Serum E2 is checked before medication and at the end of danazol therapy, but before stopping medication. MAIN OUTCOME MEASURES: Whether pregnancy is related to the change of serum E2 caused by danazol therapy. RESULTS: There were 24 pregnancies in 38 patients with invasive endometriosis after treatment. Pregnant patients had significantly lower serum E2 levels as compared with the nonpregnant patients. CONCLUSIONS: After conservative surgery for invasive endometriosis associated with infertility, the therapeutic period of danazol treatment could be shortened to 3 months. Because there is significant correlation of fecundability and serum E2 after danazol medication, serum E2 could be a guideline for predicting pregnancy or for prolonging or changing of treatment after danazol therapy. 相似文献
3.
DC Reynolds CE Leak KK Bajaj CE Stutz RL Jones KR Evans PW Yu WM Theis 《Canadian Metallurgical Quarterly》1989,40(9):6210-6217
4.
Liang Y.C. Wenjiang Zeng Pick Hong Ong Zhaoxia Gao Jun Cai Balasubramanian N. 《Electron Device Letters, IEEE》2002,23(12):700-703
In this letter, a concise process technology is proposed for the first time to enable the fabrication of good quality three-dimensional (3-D) suspended radio frequency (RF) micro-inductors on bulk silicon, without utilizing the lithography process on sidewall and trench-bottom patterning. Samples were fabricated to demonstrate the applicability of the proposed process technology. 相似文献
5.
W. L. Siew F. C. H. Oh A. S. H. Ong 《Journal of the American Oil Chemists' Society》1985,62(6):1036-1039
Some of the factors affecting cloud point determination of palm oleins are described. These are the type of container used, method of stirring, rate of stirring and bath temperature. The repeatability and reproducibility standard deviations of the method are determined from collaborative trials. Recommendations for the test are made to reduce the large variations among laboratories. 相似文献
6.
The perception and discrimination of rapidly changing texture stimuli by pigeons was examined in a target localization task. Five experienced pigeons were rewarded for finding and pecking at a randomly placed odd target block of small repeated elements embedded in a larger rectangular array of contrasting distractor elements. On dynamic color test trials, the color of the target, distractor, or both of these regions changed at rates of 100, 250, 500, or 1000 ms per frame. The number of colors appearing within such trials also varied. Pigeons performed well above chance in all test conditions, with target-associated changes producing the best discrimination. The results suggest: (a) global relational information can exclusively guide target localization behavior, (b) pigeons can perceptually group and segregate colored textured differences quite rapidly (< or = 100 ms), and (c) pigeons may possess automatic search control processes that can be captured by stimulus-driven changes in the display. 相似文献
7.
The authors examine effects on the torque that simple variations of the standard rotor pole face profile could have, basically from an elementary viewpoint of how the modified profiles affect the distribution and magnitude of the radial and tangential components of the flux density. It is observed that the average torque is mostly affected by changes that alter the dominant radial component, such as changes in the effective air gap length. The other observation that an increase in the average torque can also be obtained by a favorable shift in the torque versus angle characteristics by relatively simple changes of the rotor pole profile is not so well known. Such a shift that reduces the slope of the torque angle characteristic, skewing the curve towards the unaligned position, has two advantages: one is that the phase inductance is at its maximum positive slop and, hence, the maximum torque, when the phase is energized; second, the flatter inductance profile near the aligned position when the phase current is to be commutated would allow a faster drop off of the commutated current and, thus, a smaller negative torque 相似文献
8.
9.
V Douzdjian SS Bhaskar PK Baliga KK Gugliuzza PR Rajagopalan 《Canadian Metallurgical Quarterly》1997,20(8):1310-1314
OBJECTIVE: The racial impact on graft outcome is not well defined in diabetic recipients. The purpose of this study is to analyze our experience with kidney-alone (A) and kidney-pancreas (KP) transplantation in type 1 diabetic recipients and evaluate the impact of racial disparity on outcome. RESEARCH DESIGN AND METHODS: The records of 217 kidney transplants (118 KA, 99 KP) performed on type 1 diabetic patients between 1985 and 1995 at the Medical University of South Carolina and the University of Texas Medical Branch were reviewed. RESULTS: A total of 53 (31%) white patients and 15 (33%) black patients experienced at least one episode of biopsy-proven acute rejection of the renal graft (NS). Patient survival at 1, 2, and 5 years was similar in white (92, 87, 69%) and black (91, 91, 69%) patients (NS). Kidney graft survival at 1, 2, and 5 years in the KA group was 72, 62, and 42% in blacks, compared with 79, 76, and 53% in whites (NS). Kidney graft survival at 1, 2, and 5 years in the KP group was 92, 92, and 74% in blacks, compared with 83, 77, and 58% in whites (NS). Pancreas graft survival at 1, 2, and 5 years was 81, 81, and 81% in blacks, compared with 81, 75, and 62% in whites (NS). Cox regression analysis revealed that donor age > or = 40 years increased the risk of renal graft failure 6.2-fold (P = 0.0001), whereas the addition of a pancreas transplant to a kidney and a living-related transplant decreased the risk of failure of the kidney graft 0.2 (P = 0.005) and 0.1 times (P = 0.005). CONCLUSIONS: Our results suggest that when compared with whites, there may be a trend toward an improved kidney and pancreas graft outcome in blacks undergoing KP transplants. These findings suggest that diabetes may override the risk factors that account for the pronounced disparity in outcome observed between nondiabetic white and black recipients. 相似文献
10.
A deterministic digital simulation model with finite sum of properly weighted sinusoids is used to simulate a frequency nonselective mobile channel with LOS component. Measurement data are used to optimise the parameters. Which are then used in the deterministic simulation model. The probability distribution and level cross rate (LCR) obtained from the measured data agree well with the analytical and simulation results 相似文献