全文获取类型
收费全文 | 591755篇 |
免费 | 7687篇 |
国内免费 | 1029篇 |
专业分类
电工技术 | 10694篇 |
综合类 | 479篇 |
化学工业 | 95293篇 |
金属工艺 | 23760篇 |
机械仪表 | 19017篇 |
建筑科学 | 13265篇 |
矿业工程 | 4368篇 |
能源动力 | 14905篇 |
轻工业 | 49876篇 |
水利工程 | 7146篇 |
石油天然气 | 15040篇 |
武器工业 | 44篇 |
无线电 | 61320篇 |
一般工业技术 | 120270篇 |
冶金工业 | 101008篇 |
原子能技术 | 14748篇 |
自动化技术 | 49238篇 |
出版年
2021年 | 6116篇 |
2020年 | 4571篇 |
2019年 | 5885篇 |
2018年 | 10300篇 |
2017年 | 10432篇 |
2016年 | 10950篇 |
2015年 | 6907篇 |
2014年 | 11225篇 |
2013年 | 28142篇 |
2012年 | 17255篇 |
2011年 | 22442篇 |
2010年 | 18064篇 |
2009年 | 19801篇 |
2008年 | 20017篇 |
2007年 | 19625篇 |
2006年 | 16870篇 |
2005年 | 15270篇 |
2004年 | 14495篇 |
2003年 | 14127篇 |
2002年 | 13651篇 |
2001年 | 13121篇 |
2000年 | 12587篇 |
1999年 | 12290篇 |
1998年 | 29185篇 |
1997年 | 21072篇 |
1996年 | 16298篇 |
1995年 | 12427篇 |
1994年 | 11190篇 |
1993年 | 11010篇 |
1992年 | 8479篇 |
1991年 | 8254篇 |
1990年 | 8105篇 |
1989年 | 7877篇 |
1988年 | 7586篇 |
1987年 | 6837篇 |
1986年 | 6624篇 |
1985年 | 7486篇 |
1984年 | 6799篇 |
1983年 | 6512篇 |
1982年 | 5884篇 |
1981年 | 6012篇 |
1980年 | 5756篇 |
1979年 | 5804篇 |
1978年 | 5731篇 |
1977年 | 6398篇 |
1976年 | 8167篇 |
1975年 | 5156篇 |
1974年 | 4944篇 |
1973年 | 5033篇 |
1972年 | 4296篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
C Aufricht A Balbisi C Gerdov T Müller MA Lothaller E Balzar 《Canadian Metallurgical Quarterly》1995,207(2):59-62
A 10-year-old German shepherd dog presented with a periodontal 10 mm interproximal defect between the left mandibular fourth premolar and first molar teeth. Bone graft removed from the caudoventral portion of the ipsilateral hemimandible was placed in the defect as a component of the periodontal treatment plan. The use of bone graft likely contributed to periodontal pocket reduction. 相似文献
992.
The authors suggest that academic institutions build business-oriented policies and practices into the development of any nurse-run clinic to set the stage for financial independence when special or development funding ends. One university-affiliated program that provides 4,000 to 5,000 annual visits drastically changed its strategies when threatened with closure after free rent and other subsidies were withdrawn. The growing emphasis on ambulatory care roles for nurses at all levels makes such clinics critical to the success of the broad-based curricula of nursing education programs, as well as the clinic's value to communities they serve. Funding difficulties frequently threaten the existence of such nurse-run clinics once the initial grant funding is no longer available. This has caused a new emphasis on running such clinics in a business-wise manner. Among the strategies initiated were: direct full-pay at the time of service; a realistic business management plan; aggressive planned marketing; contracts and agreements with other agencies; obtaining provider status with selected HMOs. 相似文献
993.
A. B. Ngowi 《Building Research & Information》1998,26(6):340-350
Has specialization of professional roles obstructed the holistic approach and sustainable development? A preliminary survey in Botswana involving construction professionals found that existing procurement systems have not integrated the efforts of the different project participants and also fail to fulfil the expectations of the users. A holistic approach involving the re-integration of construction disciplines by applying new procurement methods is proposed. An integrated, holistic way of working could provide a number of synergies through the consideration of the building project as an entire system. The implications include better decision making upstream, more efficient use of resources and the mitigation of negative environmental effects downstream.
La specialisation professionnelle est-elle un obstacle a l'approche globale et au developpement durable? Une etude preliminaire menee au Botswana et portant sur les metiers de la construction a revele que les systemes d'approvisionnement actuels n'integrent pas les efforts des differents participants a un projet et ne repondent pas aux attentes des utilisateurs. Cet article propose une approche globale dont le succes repose sur la reintegration de ces metiers et sur de nouvelles methodes d'approvisionnement. Une methode de travail integree et holistique, ou un projet de construction serait considere comme un systeme complet, pourrait faire naitre un certain nombre de synergies. Cette hypothese exige un meilleur processus decisionnel en amont une utilisation plus efficace des ressources et l'attenuation des effets negatifs sur l'environnement en aval. 相似文献
La specialisation professionnelle est-elle un obstacle a l'approche globale et au developpement durable? Une etude preliminaire menee au Botswana et portant sur les metiers de la construction a revele que les systemes d'approvisionnement actuels n'integrent pas les efforts des differents participants a un projet et ne repondent pas aux attentes des utilisateurs. Cet article propose une approche globale dont le succes repose sur la reintegration de ces metiers et sur de nouvelles methodes d'approvisionnement. Une methode de travail integree et holistique, ou un projet de construction serait considere comme un systeme complet, pourrait faire naitre un certain nombre de synergies. Cette hypothese exige un meilleur processus decisionnel en amont une utilisation plus efficace des ressources et l'attenuation des effets negatifs sur l'environnement en aval. 相似文献
994.
995.
996.
997.
998.
KS Ghenghesh AS Altomi A Elgrari MR Alosta Omar AM Sharif Eddin SS Abied 《Canadian Metallurgical Quarterly》1995,72(1-2):13-15
Twenty seven Aeromonas strains (5A. hydrophila, 8A. sobria and 14A. caviae) isolated from children with diarrhoea and 34 Aeromonas strains (9A. hydrophila, 7A. sobria an 18A. caviae) isolated from children without diarrhoea were tested from haemolysin production. The results obtained showed that haemolysin production using human, horse or sheep erythrocytes was significantly associated with A.hydrophila and A sobria but not with A.caviae, regardless of whether these strains were isolated from children with or without diarrhoea. Human or horse rather than sheep erythrocytes are recommended for use in the haemolysin assay. 相似文献
999.
1000.
Guha A. Pavan A. Liu J. Rastogi A. Steeves T. 《Selected Areas in Communications, IEEE Journal on》1995,13(4):749-763
This paper describes the distributed system, network and software architecture, the application development environment, the performance, and the early lessons learned on the ATM LAN testbed Mercuri established at the Honeywell Technology Center, to develop distributed multimedia technologies for real-time control applications. We have developed a client-server-based software architecture on Sun Sparcstation-2s connected by a Fore Systems' ASX-100 ATM switch, with video processing handled by Parallax's X Video cards. The architecture enables network-transparent applications and provides simple primitives for multimedia capture, display, transmission, storage, and retrieval. A real-time multimedia-in-the-loop control application was developed as the vehicle for testing the capabilities and performance of the network. Our test measurements focus on the end-user-level performance metrics such as message throughput and round-trip delay as well as video-frame jitter under no-load and load conditions. Our results show that the maximum burst throughput that can be supported at the user level is 48 Mb/s using AAL 5, while round-trip delays for 4-kbyte messages are about 3 ms. Our experience reveals a number of performance bottlenecks and open issues in using commercial ATM switches for practical applications. Our conclusions are outlined 相似文献