全文获取类型
收费全文 | 12958篇 |
免费 | 93篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 44篇 |
综合类 | 1篇 |
化学工业 | 703篇 |
金属工艺 | 58篇 |
机械仪表 | 60篇 |
建筑科学 | 53篇 |
矿业工程 | 2篇 |
能源动力 | 91篇 |
轻工业 | 171篇 |
水利工程 | 12篇 |
石油天然气 | 7篇 |
无线电 | 303篇 |
一般工业技术 | 532篇 |
冶金工业 | 10687篇 |
原子能技术 | 28篇 |
自动化技术 | 308篇 |
出版年
2023年 | 26篇 |
2022年 | 36篇 |
2021年 | 74篇 |
2020年 | 70篇 |
2019年 | 66篇 |
2018年 | 85篇 |
2017年 | 61篇 |
2016年 | 63篇 |
2015年 | 57篇 |
2014年 | 78篇 |
2013年 | 177篇 |
2012年 | 107篇 |
2011年 | 109篇 |
2010年 | 77篇 |
2009年 | 88篇 |
2008年 | 86篇 |
2007年 | 76篇 |
2006年 | 89篇 |
2005年 | 62篇 |
2004年 | 47篇 |
2003年 | 58篇 |
2002年 | 46篇 |
2001年 | 22篇 |
2000年 | 43篇 |
1999年 | 351篇 |
1998年 | 3491篇 |
1997年 | 2056篇 |
1996年 | 1266篇 |
1995年 | 719篇 |
1994年 | 588篇 |
1993年 | 681篇 |
1992年 | 100篇 |
1991年 | 157篇 |
1990年 | 127篇 |
1989年 | 161篇 |
1988年 | 162篇 |
1987年 | 128篇 |
1986年 | 111篇 |
1985年 | 78篇 |
1984年 | 23篇 |
1983年 | 29篇 |
1982年 | 77篇 |
1981年 | 77篇 |
1980年 | 93篇 |
1979年 | 22篇 |
1978年 | 38篇 |
1977年 | 216篇 |
1976年 | 494篇 |
1975年 | 23篇 |
1973年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Polymer Bulletin - Depletion of the petroleum resources and poor flame-retardant properties of the epoxy resins drive researchers to develop an epoxy resin with good heat stability from... 相似文献
3.
Patel Sapna Kumar Dushyant Chaurasiya Nitesh Kumar Tripathi Shweta 《Semiconductors》2019,53(13):1797-1803
Semiconductors - In the present paper, analytical modeling of surface potential and drain current for hetero-dielectric double gate tunnel FET (HDG-TFET) has been done. The two dimensional (2D)... 相似文献
4.
Journal of Mechanical Science and Technology - An experimental study is performed to explore the effect of swirl and number of swirler vanes on combustion characteristics of methane inverse... 相似文献
5.
Parsania P. H. Sankhavara Dharmesh B. Chopda Jalpa Patel Jignesh P. 《Polymer Bulletin》2020,77(6):3111-3128
Polymer Bulletin - Jute and glass composites of epoxy resin of (2E, 6E)-bis(4-hydroxybenzylidene)cyclohexanone (EBHBC) were prepared by compressing molding technique using three different hardeners... 相似文献
6.
Anshuman Das Saroj Kumar Patel Bibhuti Bhusan Biswal 《Machining Science and Technology》2020,24(2):291-320
AbstractThe current research comprises of various machinability aspects of 4340 hardened alloy steel which are scrutinized with in context of improvements in main cutting force, tool flank wear, crater wear, surface roughness, micro-hardness, machined surface morphology, chip morphology, chip reduction coefficient and apparent coefficient of friction under three different cutting fluid applications i.e. compressed air, water soluble coolant and nanofluid (using eco-friendly radiator coolant as the base fluid and Al2O3 as the nanoparticle) using uncoated cermet cutting inserts and a comparative assessment was performed to select which fluid performed better in terms of various machining attributes among three cutting fluids. The minimum quantity lubrication technique (MQL) was used in which a smaller volume of coolant sprinkled at high pressure. This method is found as the most effective alternative to minimize health risks and machining costs, which is quite high in other setups. The test specimen was machined at three different cutting speeds i.e. 100, 120 and 140?m/min along with two machining parameters i.e. feed and depth of cut were kept constant respectively at 0.2?mm/rev and 0.4?mm. Outcomes made a conclusion that Al2O3 enriched ecofriendly nanocoolant outperformed both compressed air and water soluble coolant in terms of every machinability aspects. 相似文献
7.
The tensile elastic modulus (E), yield stress (σY) and microhardness (MH) of neat and binary and ternary blends of glassy semicrystalline ethylene–vinyl alcohol copolymer (EVOH), a glassy amorphous polyamide and a semicrystalline nylon‐containing ionomer covering a broad range of properties were examined. The tests were carried out on dry and water‐equilibrated samples to produce stiffer and softer materials, respectively. From the results, more accurate linear correlations were found to describe adequately the microhardness, modulus and yield stress of these strongly self‐associated polymers through hydrogen bonding. Copyright © 2003 Society of Chemical Industry 相似文献
8.
全流程低功耗设计技术的应用 总被引:1,自引:0,他引:1
SameerPatel 《电子设计应用》2004,(1):91-92
随着便携式电子设备的日益使用,要求集成电路IC及SoC的功耗越来越低。在今后日益复杂的设计中,实现一个可靠的电源网络以减小功耗变成了主要的挑战。对于使用者来说,期待每一代新产品都具有新型功能,同时也希望产品的体积小并具有较长的工作时间。解决这个难题的方法之一就是采用新型的IC设计技术,以提供小而且高效的晶体管。在整个设计流程中,为了使器件的性能和可靠性最优,电源方面的限制非常关键。例如在逻辑门应用中,由于开关从一种状态转换到另一种状态从而引起动态功耗。在开关的转换过程中,和晶体管门极相连的所有内部电容将会被… 相似文献
9.
MB Heyman JM LaBerge KA Somberg P Rosenthal C Mudge EJ Ring JD Snyder 《Canadian Metallurgical Quarterly》1997,131(6):914-919
The transjugular intrahepatic portosystemic shunt procedure is an accepted treatment for adults with complications of portal hypertension. We performed a retrospective review of all pediatric TIPS placements performed at the University of California, San Francisco between 1990 and 1996. Twelve procedures were attempted in nine children, with a mean age (+/- SD) of 9.4 +/- 3.9 years (range, 5 to 15 years) and a mean weight of 31 +/- 18 kg (range, 16 to 70 kg). The indications for TIPS placement were portal hypertension complicated by chronic variceal hemorrhage not controlled with sclerotherapy (n = 7) and hypersplenism with thrombocytopenia (n = 2). TIPS placement was successfully completed initially in seven of nine (78%) patients. Unfavorable vascular anatomy was the cause of failure in two cases. The seven patients who underwent successful TIPS placement were followed up for an average of 136 days (range, 1 to 800 days); two still have patent shunts, three underwent liver transplantation, one had a splenorenal shunt after stenosis, and one died of underlying liver disease. Variceal bleeding was controlled in four of five patients who successfully underwent TIPS placement. Shunt occlusion occurred in four patients; patency was restored by transjugular shunt revision in three, and a splenorenal shunt was performed in one. 相似文献
10.
IC Wilson TJ Gardner JM DiNatale AM Gillinov WE Curtis DE Cameron 《Canadian Metallurgical Quarterly》1993,106(5):805-810
Leukocyte depletion improves early postischemic ventricular performance in neonatal models of global myocardial ischemia. However, the rate of leukocyte reaccumulation after cardiopulmonary bypass and its subsequent impact on myocardial function is not known. This laboratory study examined the effect of leukocyte depletion on myocardial performance during the initial 6-hour period after bypass in an in situ, in vivo porcine model of neonatal cardiac surgery. Fifteen 3- to 5-day-old piglets (eight control and seven leukocyte depleted animals) were instrumented by placement of left ventricular short-axis sonomicrometry crystals and an intraventricular micromanometer catheter. Mechanical leukocyte depletion was achieved with Pall RC100 filters (Pall Biomedical, Inc., Fajardo, Puerto Rico) in the cardiopulmonary bypass circuit. Neonatal hearts were subjected to 90 minutes of hypothermic ischemia after a single dose of cold crystalloid cardioplegia. Two control animals died after the operation and were excluded from data analysis. Leukocyte filtration reduced the granulocyte count during initial myocardial reperfusion to 0.8% of control values. However, circulating granulocyte counts increased in leukocyte depleted animals throughout the postoperative period, reaching 68% of control values by 6 hours. Despite this rapid return of circulating granulocytes, animals subjected to leukocyte depletion had significantly better preservation of left ventricular performance (measured by preload recruitable stroke work, p < or = 0.02), left ventricular systolic function (measured by end-systolic pressure-volume relationship, p < or = 0.05), and ventricular compliance (p < or = 0.04) during the experiment. These changes in ventricular function were associated with a significant increase in left ventricular water content (p < or = 0.02) and tissue myeloperoxidase activity (p < or = 0.005) in control animals compared with leukocyte depleted animals. This study demonstrates that leukocyte depletion during initial reperfusion results in sustained improvement in postischemic left ventricular function despite the rapid return of granulocytes to the circulation. 相似文献