全文获取类型
收费全文 | 1216篇 |
免费 | 119篇 |
国内免费 | 13篇 |
专业分类
耳鼻咽喉 | 13篇 |
儿科学 | 37篇 |
妇产科学 | 23篇 |
基础医学 | 149篇 |
口腔科学 | 24篇 |
临床医学 | 151篇 |
内科学 | 238篇 |
皮肤病学 | 68篇 |
神经病学 | 58篇 |
特种医学 | 50篇 |
外科学 | 140篇 |
综合类 | 32篇 |
一般理论 | 2篇 |
预防医学 | 165篇 |
眼科学 | 34篇 |
药学 | 133篇 |
肿瘤学 | 31篇 |
出版年
2021年 | 13篇 |
2020年 | 11篇 |
2019年 | 13篇 |
2018年 | 26篇 |
2017年 | 18篇 |
2016年 | 18篇 |
2015年 | 9篇 |
2014年 | 29篇 |
2013年 | 54篇 |
2012年 | 63篇 |
2011年 | 65篇 |
2010年 | 44篇 |
2009年 | 45篇 |
2008年 | 58篇 |
2007年 | 63篇 |
2006年 | 50篇 |
2005年 | 56篇 |
2004年 | 40篇 |
2003年 | 41篇 |
2002年 | 40篇 |
2001年 | 30篇 |
2000年 | 30篇 |
1999年 | 26篇 |
1998年 | 29篇 |
1997年 | 31篇 |
1996年 | 32篇 |
1995年 | 21篇 |
1994年 | 21篇 |
1993年 | 19篇 |
1992年 | 20篇 |
1991年 | 14篇 |
1990年 | 8篇 |
1989年 | 22篇 |
1988年 | 14篇 |
1987年 | 20篇 |
1986年 | 20篇 |
1985年 | 21篇 |
1984年 | 16篇 |
1983年 | 19篇 |
1982年 | 12篇 |
1981年 | 13篇 |
1979年 | 15篇 |
1978年 | 10篇 |
1977年 | 12篇 |
1976年 | 8篇 |
1975年 | 8篇 |
1974年 | 10篇 |
1973年 | 13篇 |
1972年 | 14篇 |
1968年 | 11篇 |
排序方式: 共有1348条查询结果,搜索用时 15 毫秒
1.
2.
3.
神经生长因子对小鼠突触体内Ca^2+水平的调节作用 总被引:4,自引:1,他引:3
观察了多次海马内微注射NGF对小鼠突触体内游离钙水平的影响,并在离体情况下观察NGF对EGTA和CaCl2分别造成突触体内低钙和高钙状态的调节作用。结果如下:(1)在体实验表明,一定剂量的NGF可显著降低老年小鼠海马突触体内游离钙水平(P<005);(2)离体实验表明,当突触体游离钙水平降低时,适当剂量的NGF具有升高游离钙水平的作用;而突触体内游离钙水平升高时,则NGF有降低游离钙水平的作用。提示NGF对游离钙水平的双向调节作用可能是NGF改善老年性记忆衰退的作用机制。 相似文献
4.
R C Ayres S G Hübscher J Shaw C Garner R Joplin A Williams J M Neuberger 《The Journal of pathology》1991,165(2):153-161
We have produced a range of monoclonal antibodies which stain human intrahepatic bile ducts of different sizes. Amongst 26 monoclonal antibodies produced, five clones reacted specifically with bile ducts of different sizes, of which three have been maintained in culture and their viability following freezing and thawing confirmed. Staining patterns varied between normal adult liver tissue, normal fetal liver tissue and a variety of hepatobiliary diseases. The antibodies provide further evidence of the immunological heterogeneity of the human intrahepatic biliary tree and support the hypothesis that proliferating bile ductules are derived from periseptal hepatocytes. The preparation of the antibodies, their staining reactions in normal adult, normal fetal and a variety of liver diseases are described. 相似文献
5.
6.
7.
8.
Mari S. Stavanja Paul H. Ayres Daniel R. Meckley Elizabeth R. Bombick Michael F. Borgerding Michael J. Morton Charles D. Garner Deborah H. Pence James E. Swauger 《Experimental and toxicologic pathology》2006,57(4):267-281
A tiered testing strategy has been developed to evaluate the potential for new ingredients, tobacco processes, and technological developments to alter the biological activity that results from burning tobacco. A series of studies was initially conducted with cigarettes containing 3% high fructose corn syrup (HFCS) as an alternate tobacco casing material to corn syrup/invert sugar, including determination of selected mainstream cigarette smoke (MS) constituent yields, Ames assay, sister chromatid exchange (SCE) assay in Chinese hamster ovary (CHO) cells, a 30-week dermal tumor-promotion evaluation of cigarette smoke condensate (CSC) in SENCAR mice, and a 13-week subchronic inhalation study of MS in Sprague-Dawley rats. A second series of studies was conducted with cigarettes containing 3%, 4% and 5% HFCS including MS chemistry, Ames assay, SCE assay in CHO cells, and a neutral red cytotoxicity assays. Collectively, mainstream smoke chemistry, genotoxicity, dermal tumor-promotion, and inhalation toxicity studies demonstrated no differences between cigarettes with 3% HFCS and cigarettes with 3% corn syrup/invert sugar. Also, mainstream smoke chemistry and genotoxicity of cigarettes with 4% and 5% HFCS were not different from cigarettes with 3% HFCS. In conclusion, the addition of up to 5% HFCS to cigarette does not alter the mainstream smoke chemistry or biological activity of mainstream smoke or mainstream smoke condensate as compared to cigarettes with 3% corn syrup/invert sugar with regard to the parameters investigated and presented. 相似文献
9.
MY Mancao LJ Sindel PH Richardson FM Silver 《Acta paediatrica (Oslo, Norway : 1992)》1996,85(1):118-120
Croup is an acute infectious illness usually occurring in children; it is characterized by brassy cough and stridor. The main pathogens include mainly parainfluenza and influenza viruses. Recently there have been reports of prolonged croup caused by the herpes simplex viruses. We report two cases of prolonged croup due to herpes simplex types 1 and 2. We also review and summarize the reported pediatric cases of herpetic croup. 相似文献
10.
Duncan WC; Illingworth PJ; Young FM; Fraser HM 《Human reproduction (Oxford, England)》1998,13(9):2532-2540
The molecular mechanisms involved in luteolysis are still unclear in the
primate. This study aimed to investigate the effect of induced luteolysis
on the ovarian luteinizing hormone (LH) receptor and the steroidogenic
enzyme, 3beta-hydroxysteroid dehydrogenase (3beta-HSD) in the marmoset
monkey. Luteolysis was induced in the mid-luteal phase either directly by
systemic prostaglandin F2alpha (PGF2alpha), or indirectly by LH withdrawal
using systemic gonadotrophin releasing hormone antagonist (GnRHant)
treatment. The LH receptor was studied by isotopic mRNA in-situ
hybridization and in-situ ligand binding and 3beta-HSD expression was
studied using isotopic mRNA in-situ hybridization and immunohistochemistry.
Induced luteolysis was associated with a reduction in the expression of LH
receptor (P < 0.0001) and 3beta-HSD mRNA, closely followed by a
reduction in the LH receptor (P < 0.05) and 3beta-HSD protein
concentrations within 24 h. There were no differences in the findings
whether luteolysis was induced with PGF2alpha or GnRHant. This study shows
that disparate mechanisms to induce luteolysis in the primate result in an
identical rapid loss of the LH receptor and 3beta-HSD. In conclusion,
induced luteolysis leads to rapid loss of the steroidogenic pathway in
luteal cells.
相似文献