全文获取类型
收费全文 | 2658227篇 |
免费 | 191797篇 |
国内免费 | 3755篇 |
专业分类
耳鼻咽喉 | 36511篇 |
儿科学 | 86428篇 |
妇产科学 | 71477篇 |
基础医学 | 395623篇 |
口腔科学 | 73474篇 |
临床医学 | 237815篇 |
内科学 | 511932篇 |
皮肤病学 | 59215篇 |
神经病学 | 208456篇 |
特种医学 | 99104篇 |
外国民族医学 | 544篇 |
外科学 | 399955篇 |
综合类 | 53179篇 |
现状与发展 | 12篇 |
一般理论 | 936篇 |
预防医学 | 207814篇 |
眼科学 | 62448篇 |
药学 | 199056篇 |
11篇 | |
中国医学 | 5142篇 |
肿瘤学 | 144647篇 |
出版年
2019年 | 21323篇 |
2018年 | 29596篇 |
2017年 | 22211篇 |
2016年 | 24889篇 |
2015年 | 28039篇 |
2014年 | 39525篇 |
2013年 | 59480篇 |
2012年 | 81842篇 |
2011年 | 87344篇 |
2010年 | 51729篇 |
2009年 | 48994篇 |
2008年 | 82426篇 |
2007年 | 87749篇 |
2006年 | 88731篇 |
2005年 | 85805篇 |
2004年 | 82352篇 |
2003年 | 79241篇 |
2002年 | 76756篇 |
2001年 | 121899篇 |
2000年 | 125231篇 |
1999年 | 105055篇 |
1998年 | 30262篇 |
1997年 | 26492篇 |
1996年 | 27016篇 |
1995年 | 25430篇 |
1994年 | 23469篇 |
1993年 | 22138篇 |
1992年 | 81272篇 |
1991年 | 79484篇 |
1990年 | 77894篇 |
1989年 | 75057篇 |
1988年 | 68986篇 |
1987年 | 67790篇 |
1986年 | 63420篇 |
1985年 | 60893篇 |
1984年 | 45175篇 |
1983年 | 38476篇 |
1982年 | 22728篇 |
1979年 | 41992篇 |
1978年 | 30124篇 |
1977年 | 25051篇 |
1976年 | 23958篇 |
1975年 | 26033篇 |
1974年 | 31224篇 |
1973年 | 29676篇 |
1972年 | 27880篇 |
1971年 | 26615篇 |
1970年 | 24554篇 |
1969年 | 23358篇 |
1968年 | 21560篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
G Pelletier A M de Passillé M Bernier-Cardou J Morisset 《The Journal of nutrition》1987,117(10):1759-1766
In the first experiment, 52 sows, each having raised one litter, were randomly assigned to the five following groups: control (nongravid) for pregnancy (CP), 110 d pregnancy (P110), control (nongravid) for lactation (CL), 4-wk lactation with 8 (L8) and with 12 (L12) piglets. In a second experiment, 36 sows, each having raised three litters, were randomly assigned to the following groups: control group (nongravid) fed a low-energy-density, 1% tallow diet (CLED) and two lactating groups, one fed the low-energy-density diet (LLED) and one fed a high-energy-density, 10% tallow diet (LHED). At slaughter, the stomach, small and large intestine and cecum were excised, emptied and freed from fat. Lengths and pre- and post-defatting weights were measured. Portions of tissues were homogenized and analyzed for protein, pepsin, maltase, RNA and DNA. Pregnancy had no effect on the weights of the different components of the gastrointestinal tract. Liver and small intestine weights were larger in lactating sows than in the CL group. Sows nursing 12 piglets had heavier livers than those nursing 8. The fundic mucosa of the latter had higher total pepsin activity and total protein and RNA contents than that of L12 sows. LHED sows had heavier small intestine and lower total pepsin content of the fundic mucosa than LLED sows. 相似文献
992.
993.
This study evaluated health risks associated with U.S. Navy submarine duty by comparing hospitalization rates of submariners with surface ship personnel. The groups were compared using age-adjusted hospitalization rates for 16 major diagnostic categories and several specific diagnoses postulated to be submarine associated. Submarine personnel did not have significantly higher hospitalization rates for any diagnostic categories nor for any of the submarine-associated illnesses. Submariner relative risk of hospital admissions was greater for a few selected diagnoses but statistical significance was not attained. Submarine personnel had lower hospitalization rates for nearly all of the diagnostic categories examined. Reasons for these lower rates may be stringent screening of submariners, higher levels of education among submariners, difficulty of evacuation from a submarine, and the healthy-worker effect. The health status of U.S. Navy personnel does not seem to be adversely affected by submarine duty. 相似文献
994.
An enzyme-linked immunosorbent assay for the detection of Entamoeba histolytica antigens in faecal material 总被引:2,自引:0,他引:2
M S Grundy A Voller D Warhurst 《Transactions of the Royal Society of Tropical Medicine and Hygiene》1987,81(4):627-632
This paper describes a method for the detection of Entamoeba histolytica antigens in stool samples using a multi-layer ELISA. The method is sensitive and specific, showing no interference with other intestinal parasites, e.g. E. coli, E. hartmanni, Endolimax nana, Iodamoeba buetschlii, Hymenolepis nana, Giardia lamblia, Trichomonas and Ascaris. The method provides a rapid and simple screening assay for E. histolytica infections and should assist in diagnosis and epidemiological studies of the disease. 相似文献
995.
996.
A V Pokrovski? P O Kazanchian G I Kuntsevich V L Buianovski? M A Vikhert 《Vestnik khirurgii imeni I. I. Grekova》1986,137(9):56-64
Results of an examination of 39 patients are described and critically assessed. An analysis of the resolving power of the method of ultrasonic angiography in pathological formations of major vessels of the neck is given. 相似文献
997.
998.
999.
1000.