全文获取类型
收费全文 | 5070篇 |
免费 | 67篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 20篇 |
综合类 | 3篇 |
化学工业 | 274篇 |
金属工艺 | 42篇 |
机械仪表 | 48篇 |
建筑科学 | 78篇 |
能源动力 | 38篇 |
轻工业 | 87篇 |
水利工程 | 15篇 |
石油天然气 | 3篇 |
无线电 | 431篇 |
一般工业技术 | 361篇 |
冶金工业 | 3450篇 |
原子能技术 | 6篇 |
自动化技术 | 289篇 |
出版年
2023年 | 8篇 |
2022年 | 6篇 |
2021年 | 28篇 |
2020年 | 20篇 |
2019年 | 23篇 |
2018年 | 28篇 |
2017年 | 40篇 |
2016年 | 34篇 |
2015年 | 29篇 |
2014年 | 44篇 |
2013年 | 92篇 |
2012年 | 63篇 |
2011年 | 98篇 |
2010年 | 57篇 |
2009年 | 81篇 |
2008年 | 97篇 |
2007年 | 98篇 |
2006年 | 85篇 |
2005年 | 77篇 |
2004年 | 65篇 |
2003年 | 57篇 |
2002年 | 77篇 |
2001年 | 53篇 |
2000年 | 45篇 |
1999年 | 164篇 |
1998年 | 1156篇 |
1997年 | 675篇 |
1996年 | 429篇 |
1995年 | 220篇 |
1994年 | 214篇 |
1993年 | 216篇 |
1992年 | 62篇 |
1991年 | 44篇 |
1990年 | 38篇 |
1989年 | 46篇 |
1988年 | 38篇 |
1987年 | 31篇 |
1986年 | 26篇 |
1985年 | 27篇 |
1984年 | 10篇 |
1983年 | 21篇 |
1982年 | 39篇 |
1981年 | 28篇 |
1980年 | 37篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1977年 | 94篇 |
1976年 | 178篇 |
1975年 | 8篇 |
1972年 | 6篇 |
排序方式: 共有5145条查询结果,搜索用时 828 毫秒
1.
Cerebral microbleeds and cognitive decline in a hemodialysis patient: Case report and review of literature 下载免费PDF全文
Lin Li Mark Fisher Wei‐Ling Lau Hamid Moradi Alexander Cheung Gaby Thai Jason Handwerker Kamyar Kalantar‐Zadeh 《Hemodialysis international. International Symposium on Home Hemodialysis》2015,19(3):E1-E7
Cerebral microbleeds (CMBs) are small hemosiderin deposits indicative of prior cerebral microscopic hemorrhage and previously thought to be clinically silent. Recent population‐based cross‐sectional studies and prospective longitudinal cohort studies have revealed association between CMB and cognitive dysfunction. In the general population, CMBs are associated with age, hypertension, and cerebral amyloid angiopathy. In the chronic kidney disease (CKD) population, diminished estimated glomerular filtration rate has been found to be an independent risk factor for CMB, raising the possibility that a uremic milieu may predispose to microbleeds. In the end‐stage renal disease (ESRD) population on hemodialysis, the incidence of microbleeds is significantly higher compared with a control group without history of CKD or stroke. We present an ESRD patient on chronic hemodialysis with a history of gradual cognitive decline and progressive CMBs. Through this case and literature review, we illustrate the need to develop detection and prediction models to treat this frequent development in ESRD patients. 相似文献
2.
A Distributed Virtual Environment (DVE) system offers a computer-generated virtual world in which individuals located at different
places in the physical world can interact with one another. In order to achieve real-time response for a large user base,
DVE systems need to have a scalable architecture. In this paper, we present the design of a grid-enabled service oriented
framework for facilitating the construction of scalable DVE systems on computing grids. A service component called “gamelet”
is proposed, whose distinctive mark is its high mobility for supporting dynamic load sharing. We propose a gamelet migration
protocol which can ensure the transparency and efficiency of gamelet migration, and an adaptive gamelet load-balancing (AGLB)
algorithm for making gamelet redistribution decisions at runtime. The algorithm considers both the synchronization costs of
the DVE system and network latencies inherent in the grid nodes. The activities of the users and the heterogeneity of grid
resources are also considered in order to carry out load sharing more effectively. We evaluate the performance of the proposed
mechanisms through a multiplayer online game prototype implemented using the Globus toolkit. The results show that our approach
can achieve faster response times and higher throughputs than some existing approaches.
This research is supported in part by the China National Grid project (863 program) and the HKU Foundation Seed Grant 28506002. 相似文献
3.
The current Internet and wireless networks are harsh environments for transporting high-bandwidth multimedia data. We examine the technical issues involved, and describe an end-to-end solution to support a Web-based learn-on-demand system that operates in a wireless campus environment. 相似文献
4.
Math1 is essential for genesis of cerebellar granule neurons 总被引:1,自引:0,他引:1
N Ben-Arie HJ Bellen DL Armstrong AE McCall PR Gordadze Q Guo MM Matzuk HY Zoghbi 《Canadian Metallurgical Quarterly》1997,390(6656):169-172
5.
6.
MM Koerner G Tenderich K Minami M Morshuis N Mirow L Arusoglu H Gromzik S Wlost R Koerfer 《Canadian Metallurgical Quarterly》1997,63(9):1358-1360
BACKGROUND: An increasing demand for cardiac allografts for the treatment of end-stage cardiac failure has led to a shift in the traditional views about donor criteria. The use of allografts exposed to high concentrations of carbon monoxide is still under discussion. The current literature on this topic is contradictory. We describe our experience with orthotopic cardiac transplantation, using cardiac allografts after carbon monoxide poisoning. METHODS: Between March 13, 1989 and August 1, 1996, 770 orthotopic heart transplantations were performed in our center. Within this period, we accepted five cardiac allografts from brain-dead, carbon monoxide-poisoned donors. Donor history showed carbon monoxide intoxication in all cases. At the time of organ explantation, donor hemodynamic parameters were feeble in all patients. RESULTS: The postoperative course was uneventful in three of the five recipients. The overall 3-year survival rate in this small group is 40%. Induction therapy or rescue therapy with mono/polyclonal antibodies was not necessary. Myocardial right-ventricular biopsies did not show any specific signs of carbon monoxide poisoning. CONCLUSIONS: In our opinion, cardiac allografts from donors exposed to carbon monoxide can be transplanted successfully in infants and adults, if there are no signs of severe hemodynamic dysfunction in the presence of a normal central venous pressure and low-dose support with catecholamines and there are no electrocardiographic changes in combination with elevated transaminase. With extended donor criteria, the hearts of carbon monoxide-poisoned victims could increase the number of suitable organs and lower the death rate of patients on the United Network for Organ Sharing and Eurotransplant International Foundation waiting lists. 相似文献
7.
8.
The purpose of this study was to identify the optimal knot construction for interrupted dermal sutures. A synthetic braided absorbable suture, sizes 3-0 and 5-0, was selected for this evaluation. With reproducible mechanical performance tests, we determined that the construction of secure knots without ears required one additional throw as compared with secure knots with 3-mm ears. The direction of applied tension did not alter knot security, with the exception of granny knots, which required an extra throw when tension was applied parallel to the suture loop. Because interrupted dermal knot construction is accomplished without knot ears and with an applied tension parallel to the wound, one additional throw must be added to the knot to ensure knot security. 相似文献
9.
10.
Degenerate oligonucleotide primers were used in a polymerase chain reaction (PCR) to amplify a region of the recA sequence of Streptococcus gordonii Challis. The resulting PCR fragment was cloned into the suicide vector pAM6199 and introduced into strain Challis, giving rise to recombination-deficient strains in which the recA gene was specifically inactivated. 相似文献