全文获取类型
收费全文 | 2572741篇 |
免费 | 190702篇 |
国内免费 | 8781篇 |
专业分类
耳鼻咽喉 | 35832篇 |
儿科学 | 81283篇 |
妇产科学 | 73106篇 |
基础医学 | 355395篇 |
口腔科学 | 74753篇 |
临床医学 | 224999篇 |
内科学 | 510494篇 |
皮肤病学 | 60261篇 |
神经病学 | 205627篇 |
特种医学 | 106349篇 |
外国民族医学 | 709篇 |
外科学 | 401623篇 |
综合类 | 58337篇 |
现状与发展 | 8篇 |
一般理论 | 812篇 |
预防医学 | 195210篇 |
眼科学 | 58332篇 |
药学 | 186683篇 |
10篇 | |
中国医学 | 4866篇 |
肿瘤学 | 137535篇 |
出版年
2018年 | 25873篇 |
2017年 | 21574篇 |
2016年 | 23893篇 |
2015年 | 27874篇 |
2014年 | 36835篇 |
2013年 | 53050篇 |
2012年 | 71402篇 |
2011年 | 71477篇 |
2010年 | 43230篇 |
2009年 | 43441篇 |
2008年 | 65811篇 |
2007年 | 71515篇 |
2006年 | 73103篇 |
2005年 | 77792篇 |
2004年 | 76742篇 |
2003年 | 71041篇 |
2002年 | 64542篇 |
2001年 | 117737篇 |
2000年 | 119922篇 |
1999年 | 103257篇 |
1998年 | 29008篇 |
1997年 | 26005篇 |
1996年 | 26380篇 |
1995年 | 25923篇 |
1994年 | 24160篇 |
1993年 | 22595篇 |
1992年 | 84782篇 |
1991年 | 82665篇 |
1990年 | 80546篇 |
1989年 | 77805篇 |
1988年 | 72259篇 |
1987年 | 71303篇 |
1986年 | 67622篇 |
1985年 | 64452篇 |
1984年 | 48646篇 |
1983年 | 40972篇 |
1982年 | 24630篇 |
1981年 | 22271篇 |
1979年 | 45559篇 |
1978年 | 32551篇 |
1977年 | 27739篇 |
1976年 | 25248篇 |
1975年 | 27997篇 |
1974年 | 33384篇 |
1973年 | 32025篇 |
1972年 | 30267篇 |
1971年 | 28433篇 |
1970年 | 26512篇 |
1969年 | 25213篇 |
1968年 | 23602篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Anti-CD40 antibody stimulates the VLA-4-dependent adhesion of normal and LFA-1-deficient B cells to endothelium. 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《Immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We have demonstrated that anti-CD40 antibody stimulates the heterotypic adhesion of B cells to endothelial cells. This has been shown by using normal B lymphocytes and B-cell lines in a quantitative adhesion assay. When B cells, B-cell lines and Epstein-Barr virus (EBV)-transformed B cells from a patient with leucocyte adhesion deficiency (LAD) were stimulated with anti-CD40 antibody, they were found to adhere to both untreated and interleukin-1 (IL-1)-stimulated human umbilical vein endothelial cells (HUVEC), and to the lung carcinoma line A549. To identify the adhesion receptors responsible for this anti-CD40-induced adhesion, cells were pretreated with blocking antibodies prior to assay. Our results indicate that anti-CD40-stimulated adhesion of tonsillar B cells, B-cell lines RPMI-8866, JY, and an EBV-transformed LAD-cell line were predominantly dependent on the very late antigen-4 (VLA-4)-vascular cell adhesion molecule (VCAM) interaction. Anti-CD40-induced adhesion appears to be dependent on the activation of protein tyrosine kinase and protein kinase C and on the presence of divalent cations. 相似文献
993.
994.
Xu Dai-gen He Han-zhen Zhang Guo-gao B. Gansewendt H. Peter H. M. Bolt 《华中科技大学学报(医学英德文版)》1993,13(2):100-104
Monohalogenated methanes (methyl chloride, methyl bromide and methyl iodide) are mutagenic and carcinogenic. The possible mechanism of these effects, DNA methylation, was studied. DNA adducts from orgnas of F344 rats exposed to these chemicals were separated and identified with high performance liquid chromatography (HPLC) and gaschro-matography/massspectrometry (GC/ MS). DNA adducts, 7-methylguanine (7-MeG) and O6-Methylguanine(08-MeG), incorporation of14C into de novo synthesis of nucleobases could be observed in enzymatic DNA hydrolysates by HPLC and determination of the radioactivity in the fractions. The formation of DNA add,ue,ts in the studied organs was only quantitatively different. The formation of O6-MeG was further pioved by analysing the acidic hydrolysates using HPLC with non-radioactive O6MeG as internal standard. 7-MeG and 3-MeA were identified with GC/MS analysis. 相似文献
995.
996.
997.
Localized proton magnetic resonance spectroscopy of a cerebellar tumor in a two-year-old child 总被引:1,自引:0,他引:1
B. Wilken G. Helms H. J. Christen J. Bhnk J. Frahm F. Hanefeld 《Child's nervous system》1996,12(10):626-629
Noninvasive localized proton magnetic resonance spectroscopy (MRS) was used for differential diagnosis of a focal brain lesion in a 2.5-year-old girl. The clinical signs were a mild head tilt and neck pain. Magnetic resonance imaging (MRI) revealed a lesion in the right hemisphere of the cerebellum, but its nature remained obscure. In this lesion quantitative determinations of cerebral metabolites by fully relaxed, short-echo-time proton MRS revealed markedly lowered N-acetylaspartate (NAA) and pronounced elevations of choline-containing compounds (Cho) and myo-inositol (Ins), whereas metabolite concentrations in cortical gray matter and white matter were within normal ranges. The metabolite pattern of the lesion indicated loss of vital neuroaxonal tissue (low NAA) and enhanced glial proliferation (high Cho and Ins), which, together with the MRI morphology, suggested a brain tumor. The diagnosis was established by neurosurgical exploration and total extirpation of the tumor. Histology confirmed an astrocytoma (WHO II). After 2 weeks' recovery the child was discharged with no neurological signs. 相似文献
998.
999.
A prognosis of patients with a curative resected advanced cancer of the lower gastric region was worse than that of the other region of the stomach. The 5 year survival rate was only 47.3%. One of the main reasons was that a rate of lymph node recurrence was higher. In this point of view, we studied on lymphatic flow of the lower gastric region using an activated carbon particle (CH40). Lymph nodes were stained black soon after the injection of CH40 into the lower gastric wall at laparotomy. The black stained rate of an each regional lymph node was as follows. 3. 58%, 4. 17%, 5. 50%, 6. 25%, 1. 21%, 7. 58%, 8. 83%, 9. 58%, 11. 17% and 12. 33% in case of injection into the greater curvature and and 4. 31%, 6. 100%, 8. 25%, 9. 25%, 14V and 56% in case of injection into the lesser curvature. The stained rate was relatively high in 12 and 14V lymph node which we had not routinely dissected. The rates of lymph nodes stained black were related to those of cancer metastasis. The results suggest that lymphadenectomy of 12 for the cancer at the lesser curvature and that of 14V for the cancer at the greater curvature might make a prognosis of lower gastric cancer better. 相似文献
1000.
Confounders contributing to the reported associations of coffee or caffeine with disease 总被引:2,自引:0,他引:2
G B Schreiber M Robins C E Maffeo M N Masters A P Bond D Morganstein 《Preventive medicine》1988,17(3):295-309
The role of caffeine or coffee in causing or promoting the incidence of serious disease is equivocal. Two design factors may account for the discrepancies in reported findings on the effects of coffee drinking: (a) imprecision of measurement and (b) confounding variables. A study of 2,714 white U.S. adults disclosed that, of 32 risk factors analyzed by linear and logistic regression, only sex and cigarette smoking were found to be important potential confounders of caffeine and coffee intake. Partial R2 values of the other 30 risk factors were relatively small and were inconsistent for each sex. It is unlikely that any of these factors could explain any of the reported associations between caffeine or coffee consumption and certain diseases. However, certain weak associations with caffeine or coffee intake should be included in the study design when they are known to be risk factors of a disease under investigation. These factors for men are dietary fat intake, vitamin C intake, and body mass index; and for women are vitamin use, alcohol intake, stress, and perceived health status. 相似文献