全文获取类型
收费全文 | 1859篇 |
免费 | 111篇 |
国内免费 | 39篇 |
专业分类
耳鼻咽喉 | 24篇 |
儿科学 | 40篇 |
妇产科学 | 35篇 |
基础医学 | 272篇 |
口腔科学 | 31篇 |
临床医学 | 167篇 |
内科学 | 341篇 |
皮肤病学 | 63篇 |
神经病学 | 147篇 |
特种医学 | 74篇 |
外科学 | 232篇 |
综合类 | 15篇 |
预防医学 | 140篇 |
眼科学 | 60篇 |
药学 | 202篇 |
中国医学 | 3篇 |
肿瘤学 | 163篇 |
出版年
2023年 | 13篇 |
2022年 | 32篇 |
2021年 | 56篇 |
2020年 | 38篇 |
2019年 | 36篇 |
2018年 | 42篇 |
2017年 | 39篇 |
2016年 | 46篇 |
2015年 | 51篇 |
2014年 | 59篇 |
2013年 | 86篇 |
2012年 | 148篇 |
2011年 | 155篇 |
2010年 | 76篇 |
2009年 | 73篇 |
2008年 | 142篇 |
2007年 | 146篇 |
2006年 | 111篇 |
2005年 | 122篇 |
2004年 | 112篇 |
2003年 | 99篇 |
2002年 | 95篇 |
2001年 | 24篇 |
2000年 | 19篇 |
1999年 | 21篇 |
1998年 | 23篇 |
1997年 | 7篇 |
1996年 | 14篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 9篇 |
1991年 | 10篇 |
1990年 | 12篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1974年 | 2篇 |
1971年 | 2篇 |
1954年 | 1篇 |
1932年 | 1篇 |
排序方式: 共有2009条查询结果,搜索用时 15 毫秒
1.
CTLA4-Ig是一种融合免疫球蛋白,可以选择性地阻断CD28与B7的信号传导通路,导致T细胞免疫失能,诱导对特异性抗原的免疫耐受. 本文介绍了其生物学特性、免疫诱导耐受机制及在异体移植方面的研究进展和局限性,其在异体移植方面展示了良好的应用前景. 相似文献
2.
Tommi Sukuvaara Erkki M. J. Koski Aki Mäkivirta Aarno Kari 《Journal of clinical monitoring and computing》1994,10(2):117-126
A knowledge-based alarm system for intensive care monitoring was designed, built, tested on-line, and evaluated. The system is a functional prototype of a highly specific patient monitor providing alarms on hypovolemia, hyperdynamic state, left ventricular failure and hypoventilation. These intelligent alarm functions aim to maintain the quality of patient monitoring even if nurses' attention is temporarily reduced or focused elsewhere. The alarm system has an electronic access to data available in a multichannel patient monitor and the patient data management system of the intensive care unit. Median filtering, trend estimation, and rule-based reasoning are applied when processing the measured variables and estimating the patient's state. 相似文献
3.
4.
新生儿和儿童乙肝免疫 总被引:3,自引:1,他引:2
陈仕珠 《世界华人消化杂志》2006,14(27):2708-2712
自1991年WHO提出将乙型肝炎病毒(HBV)疫苗纳入新生儿计划免疫以来,绝大多数国家新生儿HBV疫苗接种覆盖率平均在90%以上,婴儿HBV疫苗接种覆盖率为85%-99%.我国HBsAg携带率从10.19%下降到0.2%-3.2%.不同地区新生儿和儿童全程接种率、首针及时接种率、免疫覆盖率差异较大.对不同新生儿和儿童HB免疫尚需注意的问题如HBV疫苗接种程序和接种剂量,早产、低体质量儿的免疫接种,HBsAg阳性母亲子女的免疫接种和母乳喂养,抗-HBs保护时间和加强免疫问题. 相似文献
5.
H Yoshida H Adachi Y Hamada T Aki T Yumoto K Morimoto T Orido 《Acta pathologica japonica》1988,38(3):325-338
The osteosarcomas were subclassified into osteoblastic, fibroblastic, chondroblastic and telangiectatic types and examined by electron microscopy. Their immunohistochemical reactions were also studied. In an overall survey of the above types, fibroblast-like cells revealed poorly developed cytoplasmic organelles with rather short, branching rough endoplasmic reticulum, mixed with osteoblast-like cells that were hardly distinguishable from the former. They appeared to be an early stage of an osteoblastic cell lineage from the distribution and development of their cell organelles and highly positive vimentin activity. The tumor cells in malignant cartilage varied in appearance from chondroblast-like to osteoblast-like cells. All types of tumor cells expressed alkaline phosphatase activity to a significant degree. Immunohistochemical staining showed a mixture of procollagen type I-positive cells among the cells positive for both procollagen type II and S-100 protein in the malignant cartilage. Irrespective of any ultrastructural differences between these various tumor cell types, they all revealed a significant degree of ALPase activity unlike other types of bone tumors, suggesting that the tumor cells which constitute the various types of osteosarcoma are derived from a common precursor cell. 相似文献
6.
Wikman H Nymark P Väyrynen A Jarmalaite S Kallioniemi A Salmenkivi K Vainio-Siukola K Husgafvel-Pursiainen K Knuutila S Wolf M Anttila S 《Genes, chromosomes & cancer》2005,42(2):193-199
Several chromosomal regions are recurrently amplified or deleted in lung tumors, but little is known about the underlying genes, which could be important mediators in tumor formation or progression. In lung cancer, the RB1-CCND1-CDKN2A pathway, involved in the G1-S transition, is damaged in nearly all tumors. In the present study, we localized a novel amplicon in lung tumors to a fragment of less than 0.5 Mb at 12q13.3-q14.1 by using comparative genomic hybridization (CGH) on cDNA microarrays. This approach enabled us to identify 10-15 genes with the most consistent amplifications. Semiquantitative RT-PCR analyses of 13 genes in this region showed that four of them (CDK4, CYP27B1, METTL1, and TSFM) were also highly up-regulated. Immunohistochemical (IHC) analysis of 141 tumor samples on a tissue microarray showed that CDK4 was expressed at a high level in 23% of lung tumors. Six (21.4%) of the tumors with high CDK4 expression (n = 28) were shown by fluorescence in situ hybridization (FISH) to contain the 12q13.3-q14.1 amplification. For CDK4, a positive correlation was found between gene copy number (FISH and CGH array), mRNA expression (RT-PCR), and level of protein expression (IHC). CDK4 expression did not correlate with CDKN2A methylation status. Amplification of CDK4 has been described in other tumor types, but its role in lung cancer remains to be elucidated. Although CDK4 amplification seems to be a relatively rare event (4.3%) in lung tumors, it indicates the significance of the RB1-CCND1 pathway in lung tumorigenesis. 相似文献
7.
Dual-probe assay for rapid detection of drug-resistant Mycobacterium tuberculosis by real-time PCR 总被引:3,自引:0,他引:3
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Wada T Maeda S Tamaru A Imai S Hase A Kobayashi K 《Journal of clinical microbiology》2004,42(11):5277-5285
Mutations in particular nucleotides of genes coding for drug targets or drug-converting enzymes lead to drug resistance in Mycobacterium tuberculosis. For rapid detection of drug-resistant M. tuberculosis in clinical specimens, a simple and applicable method is needed. Eight TaqMan minor groove binder (MGB) probes, which discriminate one-base mismatches, were designed (dual-probe assay with four reaction tubes). The target of six MGB probes was the rpoB gene, which is involved in rifampin resistance; five probes were designed to detect for mutation sites within an 81-bp hot spot of the rpoB gene, and one probe was designed as a tuberculosis (TB) control outside the rpoB gene hot-spot. We also designed probes to examine codon 315 of katG and codon 306 of embB for mutations associated with resistance to isoniazid and ethambutol, respectively. Our system was M. tuberculosis complex specific, because neither nontuberculous mycobacteria nor bacteria other than mycobacteria reacted with the system. Detection limits in direct and preamplified analyses were 250 and 10 fg of genomic DNA, respectively. The system could detect mutations of the rpoB, katG, and embB genes in DNAs extracted from 45 laboratory strains and from sputum samples of 27 patients with pulmonary TB. This system was much faster (3 h from DNA preparation) than conventional drug susceptibility testing (3 weeks). Results from the dual-MGB-probe assay were consistent with DNA sequencing. Because the dual-probe assay system is simple, rapid, and accurate, it can be applied to detect drug-resistant M. tuberculosis in clinical laboratories. 相似文献
8.
9.
Comparison of mutagenic potentials and mutation spectra of benzene metabolites using supF shuttle vectors in human cells 总被引:1,自引:0,他引:1
Benzene is a human leukemogen and the metabolites are thought to be deeply involved in benzene leukemogenesis. In a previous study we reported the molecular analysis of p-benzoquinone (p-BQ) mutagenesis by using a supF shuttle vector plasmid and here we report the mutagenesis of the other metabolites, hydroquinone (HQ) and trans, trans-muconaldehyde (MUC). HQ is a precursor of p-BQ and MUC is produced by a ring-opening metabolic pathway. We found that the HQ redox cycle produced an oxidative lesion in plasmid DNA and significant differences among the mutagenic potentials of MUC, HQ and p-BQ. HQ has stronger mutagenicity than the others. It is about 20 and 600 times stronger than p-BQ and MUC, respectively. Furthermore, we found notable differences in each mutational feature. The MUC mutational type was characterized by a high frequency of tandem base substitutions that could be due to crosslinks produced by its aldehyde moieties, while HQ was characterized by frequent deletion. This HQ feature is the same as in vivo benezene mutagenesis of Big Blue mice reported by Provost et al. in 1996 and is also quite similar to a hydrogen peroxide mutational feature. Therefore, we presume that HQ and reactive oxygen species may play an important role in benzene carcinogenesis. 相似文献
10.