全文获取类型
收费全文 | 1285446篇 |
免费 | 104888篇 |
国内免费 | 4051篇 |
专业分类
耳鼻咽喉 | 20385篇 |
儿科学 | 42068篇 |
妇产科学 | 32619篇 |
基础医学 | 166042篇 |
口腔科学 | 32164篇 |
临床医学 | 126761篇 |
内科学 | 262935篇 |
皮肤病学 | 32864篇 |
神经病学 | 102088篇 |
特种医学 | 50603篇 |
外国民族医学 | 201篇 |
外科学 | 208312篇 |
综合类 | 22748篇 |
现状与发展 | 73篇 |
一般理论 | 317篇 |
预防医学 | 87249篇 |
眼科学 | 29442篇 |
药学 | 92351篇 |
8篇 | |
中国医学 | 3007篇 |
肿瘤学 | 82148篇 |
出版年
2021年 | 13061篇 |
2020年 | 11928篇 |
2019年 | 11811篇 |
2018年 | 20331篇 |
2017年 | 17401篇 |
2016年 | 19747篇 |
2015年 | 21143篇 |
2014年 | 32503篇 |
2013年 | 40359篇 |
2012年 | 41230篇 |
2011年 | 43043篇 |
2010年 | 31697篇 |
2009年 | 33631篇 |
2008年 | 39823篇 |
2007年 | 40190篇 |
2006年 | 42715篇 |
2005年 | 38224篇 |
2004年 | 36067篇 |
2003年 | 33532篇 |
2002年 | 32323篇 |
2001年 | 64443篇 |
2000年 | 65087篇 |
1999年 | 54729篇 |
1998年 | 16398篇 |
1997年 | 14659篇 |
1996年 | 14465篇 |
1995年 | 13660篇 |
1994年 | 11453篇 |
1993年 | 10549篇 |
1992年 | 39479篇 |
1991年 | 37983篇 |
1990年 | 37061篇 |
1989年 | 35693篇 |
1988年 | 32116篇 |
1987年 | 31051篇 |
1986年 | 29305篇 |
1985年 | 27417篇 |
1984年 | 19915篇 |
1983年 | 16791篇 |
1982年 | 9463篇 |
1979年 | 17438篇 |
1978年 | 11798篇 |
1977年 | 10705篇 |
1976年 | 9142篇 |
1975年 | 10393篇 |
1974年 | 11937篇 |
1973年 | 11558篇 |
1972年 | 11093篇 |
1971年 | 10333篇 |
1970年 | 9515篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
A Moberg Wing K Wing K Tholin R Sj?str?m B Sandstr?m G Hallmans 《European journal of clinical nutrition》1992,46(8):585-595
Exposure to cadmium via the diet is known to depend to a large extent on the intake of cereal grains, particularly the high-fibre fractions of wheat. Subjects with low iron status absorb more cadmium than those with better iron status. The purpose of the present study was to determine to what extent cadmium accumulation in human placenta is affected by the intake of grain fibre and maternal iron status during pregnancy. Thirty-nine pregnant women participated in the study. In each trimester the women were requested to complete a dietary history and to allow blood samples to be taken for haemoglobin, serum ferritin and serum thiocyanate determinations, the latter as a marker for smoking. At delivery the whole placenta was taken for the determination of the cadmium concentration. The 32 women who had serum thiocyanate levels less than 70 mumol/l, who had completed at least one dietary history and from whom a blood sample was obtained in the third trimester, were included in the final statistical analyses. In the group of women who consumed less than the median intake of grain fibre and had more than 15 micrograms ferritin/l serum in the third trimester, the placenta cadmium concentration was nearly half that in the placentae of women who had consumed more grain fibre or had lower iron status in late pregnancy. 相似文献
102.
103.
104.
The degree of metabolic acidosis at birth has been calculated in cord artery and vein samples from 21 term fetuses with cord artery pH less than 7.20. The aim of the study was to compare base deficit values calculated from either Siggaard-Andersen alignment nomogram (BD blood) or the Acid-Base chart (BD extra cellular fluid, BDecf). BDblood was found to be consistently higher in the cord artery as compared with BDecf, 13.2 +/- 3.5 and 9.9 +/- 2.9 mmol/l (Mean +/- SD), respectively. A significant correlation was found between cord artery PCO2 and BDblood whereas BDecf appeared unaffected by PCO2. In cases with cord entanglement BDecf a-v differences were increased to 3.4 +/- 2.3 mmol/l as compared with the small a-v difference noted in acidotic cases without cord entanglement, 1.1 +/- 1.25 mmol/l. It is speculated that with acutely emerging, intermittent asphyxia due to cord compression, a cord artery and vein difference in metabolic acidosis may exist and where the vein captures the basal level and the artery the acute changes. It is concluded that BDecf in both cord artery and vein add valuable information on the mechanisms behind metabolic acidosis. 相似文献
105.
C K Fischer 《The Journal of reproductive medicine》1991,36(1):74-76
Fifteen cases of microtuboplasty were done as outpatient procedures at low cost and with increased patient convenience. Advances in outpatient surgery at free-standing surgery centers have allowed many new patient care innovations, and microsurgery should now be considered an outpatient procedure for gynecologic patients. Outpatient microtuboplastic surgery is not only feasible but perhaps preferable to that done as an inpatient procedure. 相似文献
106.
107.
108.
109.
110.