全文获取类型
收费全文 | 1172篇 |
免费 | 13篇 |
专业分类
电工技术 | 14篇 |
化学工业 | 101篇 |
金属工艺 | 18篇 |
机械仪表 | 13篇 |
建筑科学 | 38篇 |
矿业工程 | 3篇 |
能源动力 | 24篇 |
轻工业 | 140篇 |
水利工程 | 6篇 |
石油天然气 | 4篇 |
无线电 | 111篇 |
一般工业技术 | 156篇 |
冶金工业 | 456篇 |
原子能技术 | 14篇 |
自动化技术 | 87篇 |
出版年
2022年 | 10篇 |
2021年 | 22篇 |
2018年 | 9篇 |
2016年 | 8篇 |
2015年 | 11篇 |
2014年 | 13篇 |
2013年 | 31篇 |
2012年 | 24篇 |
2011年 | 22篇 |
2010年 | 17篇 |
2009年 | 20篇 |
2008年 | 30篇 |
2007年 | 31篇 |
2006年 | 32篇 |
2005年 | 34篇 |
2004年 | 21篇 |
2003年 | 29篇 |
2002年 | 28篇 |
2001年 | 21篇 |
2000年 | 22篇 |
1999年 | 34篇 |
1998年 | 133篇 |
1997年 | 99篇 |
1996年 | 57篇 |
1995年 | 26篇 |
1994年 | 32篇 |
1993年 | 30篇 |
1992年 | 15篇 |
1991年 | 10篇 |
1990年 | 20篇 |
1989年 | 10篇 |
1988年 | 17篇 |
1987年 | 15篇 |
1986年 | 18篇 |
1985年 | 17篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 8篇 |
1981年 | 11篇 |
1980年 | 12篇 |
1979年 | 7篇 |
1978年 | 8篇 |
1977年 | 13篇 |
1976年 | 29篇 |
1975年 | 13篇 |
1974年 | 10篇 |
1973年 | 9篇 |
1972年 | 10篇 |
1970年 | 8篇 |
1926年 | 6篇 |
排序方式: 共有1185条查询结果,搜索用时 15 毫秒
11.
PA Conrad K Sverlow M Anderson J Rowe R BonDurant G Tuter R Breitmeyer C Palmer M Thurmond A Ardans 《Canadian Metallurgical Quarterly》1993,5(4):572-578
Parasite-specific antibody responses were detected using an indirect fluorescent antibody (IFA) test in cattle that were naturally or experimentally infected with Neospora parasites. The test was developed using Neospora tachyzoites isolated from an aborted bovine fetus and grown in bovine cell cultures (isolate BPA1). In all cases, infections were confirmed by the identification of Neospora tachyzoites and/or bradyzoite cysts in fetal or calf tissues using an immunoperoxidase test procedure. Fifty-five naturally infected cows that aborted Neospora-infected fetuses had titers of 320-5,120 at the time of abortion. The titer of 6 cows that were serologically monitored over a prolonged period decreased to 160-640 within 150 days after they aborted infected fetuses. Two of the cows showed an increase in their Neospora titers during their subsequent pregnancy, and they gave birth to congenitally infected calves that had precolostral titers of 10,240-20,480. Postcolostral titers of these calves and of 4 other calves with congenital Neospora infections were all > or = 5,120, whereas calves with no detectable parasites had titers < or = 160. Two pregnant heifers that were experimentally infected with the BPA1 isolate at approximately 120 days gestation seroconverted to Neospora antigens within 9 days and developed peak titers of 5,120 and 20,480 within 32 days of infection. The fetus taken by caesarean section 32 days postinfection from 1 heifer and the full-term calf born to the other had Neospora titers of 640 and 10,240, respectively.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
12.
Li S. Zhang H. Lu P. Zhu W. Edelman H. Rea C. Tabat N. Mao S. Brown D. Montemorra M. Palmer D. 《IEEE transactions on magnetics》2006,42(12):3874-3879
In perpendicular recording, substantial erasure of the stored data patterns can occur during the writing process. Among all those erasure processes, side-track erasure (STE) is one of the critical issues in drive head/media integration. Unlike the adjacent track erasure (ATE) process, the locations of the STE affected areas are often many tens of tracks away from the central writing track location. In this work, we report on an experimental investigation and quantification of the general attributes and the origins of the STE processes in various situations. Particularly, we thoroughly characterize some distinctive signatures and behaviors of STE processes by employing both the amplitude- and bit-error-rate-based STE measurement methods in combination with a novel magnetic force microscope characterization technique 相似文献
13.
A theoretical analysis of the surface ocean current mapping performance of land-based bistatic and monostatic Δk -radars is presented. Contour maps of the calculated surface current resolution achievable with both configurations are presented and compared. For the assumed surface conditions, both configurations are seen to be capable of resolving 5 cm/s currents with 100 m spatial resolution out to ranges of several kilometers using reasonable dwell times 相似文献
14.
One hundred and seven consecutive patients presenting with significant peptic ulcer haemorrhage were randomised to endoscopic injection with 3-10 ml of 1:100,000 adrenaline (55 patients, group 1) or to a combination of adrenaline and 5% ethanolamine (52 patients, group 2). All had major stigmata of haemorrhage and endoscopic injection was undertaken by a single endoscopist. The groups were well matched with regard to risk factors. Rebleeding occurred in eight of the group 1 patients and seven in the group 2 patients; surgical operation rates, median blood transfusion requirements, and hospital stay were similar in both groups. The efficacy of either form of injection was similar whether patients presented with active bleeding or a non-bleeding visible vessel. No complications occurred. In patients presenting with significant peptic ulcer bleeding, the addition of a sclerosant confers no advantage over injection with adrenaline alone. 相似文献
15.
16.
Collision Detection for Animation using Sphere-Trees 总被引:13,自引:0,他引:13
The detection of collisions between moving polyhedral objects is one of the most computationally intensive tasks in the computer animation process. The use of object-oriented techniques to encapsulate data within the objects' structures compounds this problem through the requirement for inter-object message passing in order to obtain geometric information for collision detection. The REALISM system decreases the time for collision detection by using a three stage process. The first stage identifies objects in the same locality using a global bounding volume table. The second stage locates regions of possible collision using a sphere-tree data structure (a hierarchical tree of spheres based on octree-type spatial subdivision). The final stage finds intersections between polygonal faces of the objects that are contained within the intersecting pairs of leaf nodes. Hence the algorithm uses a spherical geometry approximation rapidly to locate regions of potential collisions and then uses a local intersection test with actual object geometry information. The system is therefore fast and accurate. Tests for various geometric objects support this and show performance improvements of jive times over traditional polyhedral intersection tests. 相似文献
17.
Investigated the similarity of reference effects for different delay conditions by testing the independence of reference and delay effects in 4 experiments, using 5 young adult observers. The critical independence property was whether the spatial variables (displacement separation from the visual reference) combined independently of the temporal variable (delay). This kind of independence did not hold for displacement discrimination at delays of 50 msec and 2,000 msec. When a test for the independence property was conducted at delays of 500 msec and 4,000 msec, observers reported no perceived movement. For these longer delays, the property was satisfied. These results are discussed using the general concept of a psychophysical mechanism. Such a mechanism combines the effects of several stimulus variables into a single mediating representation. By this analysis, at least 2 mechanisms must mediate the reference effect on displacement discrimination, one for delays of 200 msec and less and another for delays of 500 msec and more. (49 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
18.
The photolithography step in the semiconductor manufacturing process becomes increasingly critical as linewidths decrease for the next generation of integrated electronics. It therefore becomes necessary to reduce variations in photoresist parameters such as resist film thickness and photoactive compound concentration during manufacture. In this paper, we present a simple feedback scheme for accurately regulating these parameters. Our approach involves obtaining a simple, static process model the coefficients of which are recursively adjusted based on previous wafer measurements. We use this adaptive model to determine appropriate input setpoints for the next wafer. The effectiveness of this scheme in reducing process drift is exhibited by experimental data. Our results supports the widespread contention that modern feedback control offers the promise of improving the semiconductor manufacturing processes, often with relative ease and minimal capital cost 相似文献
19.
Jarvis Tyler Clough Jordan Cox Jane Petersen Konnor Sailsbery Mitchell Robertson Connor Moncur Tyler Palmer Katie Lund Darren 《Water Resources Management》2021,35(2):745-756
Water Resources Management - A traditional cost-benefit analysis of potential water interventions in a given locality is a laborious and time-intensive process. To help decision makers identify... 相似文献
20.
D. D. Palmer D. K. Rehbein J. F. Smith O. Buck 《Journal of Nondestructive Evaluation》1988,7(3-4):167-174
It has been shown that the acoustic response of imperfect interfaces may be described by a quasi-static spring model. In the present paper, experimental data on the geometry of the contacts between two diffusion-bonded blocks have been used to determine the spring stiffness of such interfaces which have been correlated with experimentally determined ultrasonic reflection coefficients. The correlation between the theoretical reflection coefficient and the spring stiffness was found to be in excellent agreement with experimentally-observed values, if the disbonds are of infinitesimally small thickness. For disbonds of finite thickness, the agreement is less satisfactory. Reasons for the discrepancy in the latter case are unknown at the present time. 相似文献