全文获取类型
收费全文 | 1784篇 |
免费 | 157篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 7篇 |
儿科学 | 91篇 |
妇产科学 | 13篇 |
基础医学 | 268篇 |
口腔科学 | 54篇 |
临床医学 | 179篇 |
内科学 | 332篇 |
皮肤病学 | 50篇 |
神经病学 | 116篇 |
特种医学 | 179篇 |
外国民族医学 | 1篇 |
外科学 | 158篇 |
综合类 | 61篇 |
一般理论 | 1篇 |
预防医学 | 202篇 |
眼科学 | 24篇 |
药学 | 132篇 |
中国医学 | 2篇 |
肿瘤学 | 81篇 |
出版年
2021年 | 20篇 |
2020年 | 15篇 |
2019年 | 19篇 |
2018年 | 24篇 |
2017年 | 25篇 |
2016年 | 37篇 |
2015年 | 47篇 |
2014年 | 43篇 |
2013年 | 70篇 |
2012年 | 57篇 |
2011年 | 70篇 |
2010年 | 53篇 |
2009年 | 64篇 |
2008年 | 66篇 |
2007年 | 61篇 |
2006年 | 57篇 |
2005年 | 48篇 |
2004年 | 69篇 |
2003年 | 50篇 |
2002年 | 43篇 |
2001年 | 48篇 |
2000年 | 46篇 |
1999年 | 45篇 |
1998年 | 68篇 |
1997年 | 70篇 |
1996年 | 66篇 |
1995年 | 47篇 |
1994年 | 51篇 |
1993年 | 45篇 |
1992年 | 39篇 |
1991年 | 28篇 |
1990年 | 36篇 |
1989年 | 35篇 |
1988年 | 39篇 |
1987年 | 36篇 |
1986年 | 33篇 |
1985年 | 26篇 |
1984年 | 22篇 |
1983年 | 16篇 |
1982年 | 25篇 |
1981年 | 16篇 |
1980年 | 17篇 |
1979年 | 16篇 |
1978年 | 14篇 |
1977年 | 16篇 |
1976年 | 20篇 |
1975年 | 12篇 |
1972年 | 7篇 |
1971年 | 10篇 |
1968年 | 8篇 |
排序方式: 共有1951条查询结果,搜索用时 15 毫秒
1.
2.
3.
Ketai LH; Williamson MR; Telepak RJ; Levy H; Koster FT; Nolte KB; Allen SE 《Radiology》1994,191(3):665
4.
Protein kinase-A and the effects of parathyroid hormone on phosphate uptake in opossum kidney cells 总被引:3,自引:0,他引:3
Current evidence indicates that signal transduction after receptor binding of PTH involves the stimulation of adenylate cyclase as well as stimulation of phosphoinositide metabolism. Recent studies, showing that PTH alters phosphate transport in opossum kidney cells at concentrations which do not increase cAMP production and that activators of protein kinase-C also alter phosphate transport, have led to the suggestion that there is a dual mechanism for the regulation of phosphate transport by PTH, namely, protein kinase-C at physiological levels of PTH and cAMP at higher levels of PTH. The present studies were designed to evaluate the relationship between cAMP-dependent protein kinase (PK-A), a more sensitive indicator of alterations in cAMP metabolism than measurements of total cellular cAMP, and phosphate transport in opossum kidney cells, in response to bovine (b)PTH 1-34 and [Nle8,Nle18,Tyr34]bPTH 3-34 amide. While bPTH 1-34 markedly stimulated cAMP accumulation (half-maximal stimulation between 1 and 10 nM), PTH 3-34 analog did not. Phosphate transport was inhibited in a dose-dependent manner by bPTH 1-34, with half-maximal effect occurring between 0.1 and 1 nM. [Nle8,Nle18,Tyr34]bPTH 3-34 amide also altered phosphate transport, although this peptide was 3 orders of magnitude less potent than bPTH 1-34. PK-A activity increased in response to bPTH 1-34 and correlated closely with the effects of PTH on phosphate transport. [Nle8,Nle18,Tyr34]bPTH 3-34 amide, which did not appear to increase cAMP, also resulted in a significant increase in the activity of PK-A. Studies of inhibition of cAMP accumulation using 2',5'-dideoxyadenosine demonstrated that while this agent markedly inhibited the accumulation of cAMP in response to PTH, the effects of PTH on phosphate transport were not altered. However, in spite of the reduction in cAMP the activation of PK-A was similar to control. These data indicate that the effects of PTH peptides on phosphate transport are more closely related to changes in the activity of PK-A than to levels of total cAMP. Activation of PK-A in response to PTH is demonstrable at the lowest doses of PTH that alter phosphate transport. 相似文献
5.
6.
7.
K S Betts 《Environmental health perspectives》1997,105(6):594-596
8.
S. van Ruth† EBL van Dorst‡ MR Canninga-van Dijk§ MS de Bruin-Weller† 《Journal of the European Academy of Dermatology and Venereology》2007,21(5):678-680
Cutaneous metastasis of vaginal carcinoma is extremely rare. So far, the total number of reported skin metastasis of vaginal carcinoma is only one. We present another case with an unusual manifestation of vagina carcinoma metastasis: skin metastasis presenting as a leg ulcer on the lower leg. 相似文献
9.
10.
To examine supplement purchase practices and attitudes toward supplements of rural and urban elderly, two questionnaires were designed. One questionnaire included demographic questions, an attitude scale, and questions concerning supplements purchases and sources of information about nutrition. The second questionnaire contained an advertisement about calcium supplements followed by questions regarding means to "improve calcium" and health concerns. The rural elderly had a significantly lower mean education level and a significantly higher number of misconceptions. The average expenditures on supplements were $52.00 per month for the total group and sources of information were media, physicians, family and friends. In response to the advertisement, nearly one-third of the respondents reported that they would be unlikely to take calcium supplements to improve calcium even though 86.7% stated they would take calcium supplements to prevent health problems and 51.7% believed there could be dangers in taking calcium supplements. The most commonly reported means to improve calcium were to increase milk and to eat cheese (86.7% each). Contradictions in the responses may indicate that these elderly are susceptible to advertising implying supplements are needed to prevent health problems. 相似文献