全文获取类型
收费全文 | 765261篇 |
免费 | 11031篇 |
国内免费 | 2765篇 |
专业分类
电工技术 | 14527篇 |
技术理论 | 5篇 |
综合类 | 1726篇 |
化学工业 | 123380篇 |
金属工艺 | 30831篇 |
机械仪表 | 23989篇 |
建筑科学 | 18296篇 |
矿业工程 | 5439篇 |
能源动力 | 19081篇 |
轻工业 | 67817篇 |
水利工程 | 8956篇 |
石油天然气 | 18152篇 |
武器工业 | 280篇 |
无线电 | 80067篇 |
一般工业技术 | 151219篇 |
冶金工业 | 132657篇 |
原子能技术 | 17621篇 |
自动化技术 | 65014篇 |
出版年
2021年 | 8140篇 |
2020年 | 5845篇 |
2019年 | 7314篇 |
2018年 | 12206篇 |
2017年 | 12297篇 |
2016年 | 13025篇 |
2015年 | 8846篇 |
2014年 | 14171篇 |
2013年 | 36123篇 |
2012年 | 22491篇 |
2011年 | 29526篇 |
2010年 | 23704篇 |
2009年 | 25801篇 |
2008年 | 26468篇 |
2007年 | 26223篇 |
2006年 | 22872篇 |
2005年 | 20345篇 |
2004年 | 18891篇 |
2003年 | 18343篇 |
2002年 | 17760篇 |
2001年 | 17287篇 |
2000年 | 16450篇 |
1999年 | 16260篇 |
1998年 | 37916篇 |
1997年 | 27469篇 |
1996年 | 21265篇 |
1995年 | 16138篇 |
1994年 | 14693篇 |
1993年 | 14252篇 |
1992年 | 11060篇 |
1991年 | 10649篇 |
1990年 | 10548篇 |
1989年 | 10338篇 |
1988年 | 9795篇 |
1987年 | 8795篇 |
1986年 | 8601篇 |
1985年 | 9725篇 |
1984年 | 8994篇 |
1983年 | 8501篇 |
1982年 | 7643篇 |
1981年 | 7905篇 |
1980年 | 7415篇 |
1979年 | 7622篇 |
1978年 | 7456篇 |
1977年 | 8175篇 |
1976年 | 10405篇 |
1975年 | 6743篇 |
1974年 | 6431篇 |
1973年 | 6510篇 |
1972年 | 5513篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
951.
A Colli M Cocciolo C Riva L Marcassoli M Pirola P Di Gregorio G Buccino 《Canadian Metallurgical Quarterly》1993,72(3):677-682
BACKGROUND: Ascites in patients with hepatocellular carcinoma (HCC) is a poorly characterized subgroup of malignancy-related ascites. Not only the underlying liver disease, but also the tumor growth and spread contributes to the ascites formation. The authors differentiated ascites in HCC from other types of ascites. METHODS: The authors analyzed the ascitic fluid of 185 consecutive patients (89 liver cirrhosis, 33 HCC, 31 peritoneal carcinomatosis, 22 liver metastases, 10 spontaneous bacterial peritonitis). RESULTS: Each subgroup showed a typical pattern. Compared with the cirrhotic patients, those with HCC showed a higher frequency of positive cytologic findings (4 of 33 versus 0/89, P < 0.004), elevated fibronectin concentration (10/33 versus 8/89, P < 0.004), and elevated polymorphonuclear cell count (10/33 versus 5/89 P < 0.004). CONCLUSIONS: A significant number of patients with ascites and HCC patients showed signs of peritoneal infiltration with positive cytologic findings and increased concentration of fibronectin. Moreover, neutrocytic ascites without signs of superinfection is relatively common (30%). 相似文献
952.
953.
M. Landí n M. P. Gonz lez C. Souto A. Concheiro J. L. G mez-Amoza R. Martí nez-Pacheco 《Drug development and industrial pharmacy》1993,19(10):1211-1220
In tests of direct-compression hydrochlorothiazide tablets prepared with either of two varieties of microcrystalline cellulose (Avicel PH 101 and Avicel PH 102), PH 102 tablets had better mechanical properties (owing to lower compressibility of mixtures and greater Interparticle bonding), while PH 101 tablets released the active principle faster. These differences are related to observed differences In tablet micropore structure. 相似文献
954.
955.
956.
M. A. Maksimov 《Metallurgist》1995,39(6):118
Translated from Metallurg, Vol. 39, No. 6, p. 45, June, 1995. 相似文献
957.
Harame D.L. Comfort J.H. Cressler J.D. Crabbe E.F. Sun J.Y.-C. Meyerson B.S. Tice T. 《Electron Devices, IEEE Transactions on》1995,42(3):455-468
A detailed review of SiGe epitaxial base technology is presented, which chronicles the progression of research from materials deposition through device and integration demonstrations, culminating in the first SiGe integrated circuit application. In part I of this paper, the requirements and processes for high-quality SiGe film preparation are discussed, with emphasis on fundamental principles. A detailed overview of SiGe HBT device design and implications for circuit applications is then presented 相似文献
958.
A Schultz 《Canadian Metallurgical Quarterly》1995,91(7):31-34
With change abounding in Canada's health care system, nurses must redefine their roles. One role is in health promotion, a field where nurses have created a unique identity for themselves. But before advocating, the concept must be fully understood. 相似文献
959.
Since foodborne diseases, especially those caused by bacteria, have become an increasingly important public health problem, the Authors conducted a survey in order to evaluate the organization of, and the intervention carried out by, six Public Health Services in the Lombardia region, after reports of foodborne diseases outbreaks. Lack of correct methodology was detected, not to mention the usual omission of epidemic curves and attack rates. Besides, too many microbiological tests were made and it took too much time to take care of and to report the outbreaks to Regional and National Health Authorities. Forty-one outbreaks were examined: 415 cases occurred (AR: 28.7%), most of which home-made food-related. In 25 outbreaks the suspected food vehicles were eggs or fish, but only 5 of them were confirmed by laboratory tests. Salmonella enterica, either serovar Eenteritidis or group D, appeared responsible for 26 of the outbreaks [corrected]. 相似文献
960.