全文获取类型
收费全文 | 19502篇 |
免费 | 2385篇 |
国内免费 | 6篇 |
专业分类
21893篇 |
出版年
2021年 | 236篇 |
2020年 | 172篇 |
2019年 | 210篇 |
2018年 | 248篇 |
2017年 | 217篇 |
2016年 | 387篇 |
2015年 | 613篇 |
2014年 | 671篇 |
2013年 | 838篇 |
2012年 | 946篇 |
2011年 | 967篇 |
2010年 | 605篇 |
2009年 | 610篇 |
2008年 | 811篇 |
2007年 | 897篇 |
2006年 | 792篇 |
2005年 | 751篇 |
2004年 | 744篇 |
2003年 | 688篇 |
2002年 | 661篇 |
2001年 | 456篇 |
2000年 | 470篇 |
1999年 | 480篇 |
1998年 | 270篇 |
1997年 | 224篇 |
1996年 | 243篇 |
1995年 | 214篇 |
1994年 | 214篇 |
1993年 | 231篇 |
1992年 | 362篇 |
1991年 | 351篇 |
1990年 | 328篇 |
1989年 | 294篇 |
1988年 | 303篇 |
1987年 | 296篇 |
1986年 | 273篇 |
1985年 | 313篇 |
1984年 | 285篇 |
1983年 | 228篇 |
1982年 | 207篇 |
1981年 | 191篇 |
1980年 | 172篇 |
1979年 | 233篇 |
1978年 | 205篇 |
1977年 | 172篇 |
1976年 | 201篇 |
1975年 | 191篇 |
1973年 | 196篇 |
1972年 | 182篇 |
1970年 | 165篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Carl E. Anderson 《The Western journal of medicine》1968,108(5):385-387
The Governor''s Survey on Efficiency and Cost Control, established by Governor Reagan''s executive order, was a non-profit, bipartisan, privately financed management analysis of State administration conducted by private citizens, including physicians, during 1967 for the purpose of achieving improvement in administrative procedure and operating economies in State government.State employees and appointed department heads offered many valuable suggestions and cooperated fully with the survey team.Two hundred recommendations were submitted to the Governor for improvement in the Departments of Public Health and Mental Hygiene, the Office of Health Care Services and the organizations under the Secretary of Human Relations.The recommendations for the health-related administrative units concerned reorganization and consolidation of departments and units, improvement in administrative and operating methods and improvement of services. Annual savings of several hundred million dollars could result.None of the recommendations were for reduction in services and none concerned individual employees or appointees.Assistance in and support for the implementation of the recommendations will be needed from legislators, responsible citizens and organizations interested in efficient and economical government. 相似文献
82.
83.
Streptococcus faecium var. casselifavus, nov. var 总被引:7,自引:1,他引:6
Streptococcus faecium var. casseliflavus is a gram-positive, spherical cell. The cells occur chiefly as pairs within chains and elongate to ogive-shaped cells during growth. Growth is good on 5% bile salts-agar and in broth at 10 C, and in broth adjusted to pH 9.6 or containing 6.5% NaCl, but many strains fail to grow at 45 C. Litmus is reduced rapidly prior to formation of an acid curd. Few strains release ammonia from arginine or serine. The organism is not proteolytic and does not produce H(2)S or acetylmethylcarbinol, reduce nitrate, decarboxylate tyrosine, or produce slime on sucrose-agar. Most strains survive heating to 60 C for 30 min. It produces gray colonies on potassium tellurite agar, reduces 2,3,5-triphenyltetrazolium-HCl to a pink color, and ferments cellobiose, dextrin, maltose, mannose, and sorbitol, thus resembling S. faecalis. Like S. faecium, it produces peroxidase but not catalase on heated blood media, dissimilates malate, and ferments arabinose, melibiose, and salicin, but not melezitose. Like both species, it ferments dextrose, galactose, lactose, mannitol, sucrose, trehalose, and citrate. Properties peculiar to the variant include the high pH limiting initiation and termination of growth; the fermentation of alpha-methyl-d-glucoside, raffinose, and xylose; motility; and growth without blue button formation in ethyl violet broth. The water-soluble, pale lemon-yellow pigment is released into the aqueous phase only after the cell envelope is altered by fat solvents. The bacterium thrives as an epiphyte on plants. 相似文献
84.
85.
The fine structure of compensatory growth in the rat kidney after unilateral nephrectomy 总被引:4,自引:0,他引:4
W A Anderson 《The American journal of anatomy》1967,121(2):217-247
86.
87.
88.
89.
90.
Separation of the antihemophilic factor (F. 8) from fibrinogen with thrombin and manganese chloride 总被引:2,自引:0,他引:2