全文获取类型
收费全文 | 4337篇 |
免费 | 25篇 |
专业分类
电工技术 | 5篇 |
综合类 | 3篇 |
化学工业 | 108篇 |
金属工艺 | 3篇 |
机械仪表 | 2篇 |
建筑科学 | 22篇 |
矿业工程 | 1篇 |
能源动力 | 9篇 |
轻工业 | 59篇 |
无线电 | 51篇 |
一般工业技术 | 68篇 |
冶金工业 | 3988篇 |
原子能技术 | 5篇 |
自动化技术 | 38篇 |
出版年
2021年 | 7篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 7篇 |
2016年 | 9篇 |
2015年 | 11篇 |
2014年 | 11篇 |
2013年 | 17篇 |
2012年 | 6篇 |
2011年 | 17篇 |
2010年 | 14篇 |
2009年 | 16篇 |
2008年 | 20篇 |
2007年 | 25篇 |
2006年 | 16篇 |
2005年 | 11篇 |
2004年 | 11篇 |
2003年 | 17篇 |
2002年 | 13篇 |
2001年 | 12篇 |
2000年 | 17篇 |
1999年 | 146篇 |
1998年 | 1250篇 |
1997年 | 692篇 |
1996年 | 438篇 |
1995年 | 227篇 |
1994年 | 197篇 |
1993年 | 252篇 |
1992年 | 38篇 |
1991年 | 51篇 |
1990年 | 56篇 |
1989年 | 67篇 |
1988年 | 67篇 |
1987年 | 55篇 |
1986年 | 38篇 |
1985年 | 44篇 |
1984年 | 10篇 |
1983年 | 15篇 |
1982年 | 25篇 |
1981年 | 23篇 |
1980年 | 30篇 |
1979年 | 5篇 |
1978年 | 12篇 |
1977年 | 104篇 |
1976年 | 202篇 |
1975年 | 18篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1967年 | 3篇 |
排序方式: 共有4362条查询结果,搜索用时 15 毫秒
61.
JS Kim I Lopez PL DiPatre F Liu A Ishiyama RW Baloh 《Canadian Metallurgical Quarterly》1999,52(1):40-44
Immunocytochemical examination for mitochondrial protein and cytochrome oxidase was performed to demonstrate oncocytes in normal adenohypophysis obtained from 28 patients of various age. A small number of solitary large epithelial cells showed intense cytoplasmic granular immunoreactivities for mitochondrial protein and cytochrome oxidase. The proportions of the cells positive for the former and the latter ranged from 0% to 5.9% (mean+/-SD; 1.5+/-1.7%) and from 0% to 4.9% (1.4+/-1.6%), respectively. These cells were either absent or extremely rare in young patients (under 10 years) but tended to increase in number with age (P < 0.0001). On the other hand, the mirror section technique showed that most of these cells were negative for adenohypophysial hormones, but a few of them were faintly positive for: alpha-subunit (8.0%), beta-subunits of follicle-stimulating hormone (4.8%), luteinizing hormone (2.5%), thyroid-stimulating hormone (1.0%), and growth hormone (0.5%), and were negative for prolactin and adrenocorticotropic hormone. We considered that these cells represent oncocytes that exist in varying numbers in normal adenohypophysis. It was suggested that oncocytes in normal adenohypophysis share various common features with tumorous oncocytes of pituitary oncocytomas. 相似文献
62.
Barton Kristine A.; Blanchard Edward B.; Veazy Connie 《Canadian Metallurgical Quarterly》1999,11(4):490
This article describes assessment issues in behavioral medicine and a typology of uses of self-monitoring in behavioral medicine assessment. Illustrative examples of the use of self-monitoring in behavioral medicine assessment are presented. Current issues, and methodological concerns, in self-monitoring for behavioral medicine assessment are described along with some ideas for solutions of these issues and concerns. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
63.
GH Posner MH Parker J Northrop JS Elias P Ploypradith S Xie TA Shapiro 《Canadian Metallurgical Quarterly》1999,42(2):300-304
In only three chemical operations, natural trioxane lactone artemisinin (1) was converted into a series of C-10 carbon-substituted 10-deoxoartemisinin compounds 4-9. The three steps involved lactone reduction, replacement of the anomeric lactol OH by F using diethylaminosulfur trifluoride, and finally boron trifluoride-promoted substitution of F by aryl, heteroaryl, and acetylide nucleophiles. All of these C-10 nonacetal, chemically robust, enantiomerically pure compounds 4-9 have high antimalarial potencies in vitro against Plasmodium falciparum malaria parasites, and furans 5a and 5b and pyrrole 7a are antimalarially potent also in vivo even when administered to rodents orally. 相似文献
64.
65.
66.
67.
68.
69.
70.
A new approach for determining the contributions of emission sources to concentrations of particulate matter and gases is developed using the chemical mass balance (CMB) method and the U.S. EPA's National Emission Inventory (NEI). The approach apportions combined gas-phase and condensed-phase concentrations of individual compounds as well as PM(2.5) mass. Because the NEI is used to provide source emission profiles for CMB analysis, the method generates information on the consistency of the NEI with ambient monitoring data. The method also tracks secondary species to primary source emissions, permitting a more complete accounting of the impact of aggregated source types on PM(2.5) mass concentrations. An example application is presented using four years of monitoring data collected at eight sites in the Southeastern Aerosol Research and Characterization (SEARCH) network. Including both primary and secondary species, area sources contributed 2.0-3.7 μg m(-3) (13-26%), point sources contributed 3.0-4.6 μg m(-3) (22-33%), and mobile sources contributed 1.0-6.0 μg m(-3) (9-42%) to mean PM(2.5) mass concentrations. Whereas the NEI generally accounts for the ambient concentrations of gases and particles, certain anomalies are identified, especially related to carbonaceous compounds and dust. 相似文献