全文获取类型
收费全文 | 2300篇 |
免费 | 269篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 17篇 |
儿科学 | 63篇 |
妇产科学 | 34篇 |
基础医学 | 339篇 |
口腔科学 | 110篇 |
临床医学 | 236篇 |
内科学 | 446篇 |
皮肤病学 | 35篇 |
神经病学 | 179篇 |
特种医学 | 164篇 |
外国民族医学 | 1篇 |
外科学 | 318篇 |
综合类 | 77篇 |
一般理论 | 2篇 |
预防医学 | 215篇 |
眼科学 | 48篇 |
药学 | 116篇 |
中国医学 | 2篇 |
肿瘤学 | 178篇 |
出版年
2023年 | 16篇 |
2022年 | 19篇 |
2021年 | 28篇 |
2019年 | 20篇 |
2018年 | 37篇 |
2017年 | 17篇 |
2016年 | 23篇 |
2015年 | 38篇 |
2014年 | 46篇 |
2013年 | 62篇 |
2012年 | 96篇 |
2011年 | 95篇 |
2010年 | 61篇 |
2009年 | 54篇 |
2008年 | 88篇 |
2007年 | 120篇 |
2006年 | 94篇 |
2005年 | 116篇 |
2004年 | 99篇 |
2003年 | 99篇 |
2002年 | 97篇 |
2001年 | 68篇 |
2000年 | 95篇 |
1999年 | 82篇 |
1998年 | 68篇 |
1997年 | 67篇 |
1996年 | 54篇 |
1995年 | 41篇 |
1994年 | 54篇 |
1993年 | 21篇 |
1992年 | 39篇 |
1991年 | 45篇 |
1990年 | 57篇 |
1989年 | 51篇 |
1988年 | 45篇 |
1987年 | 39篇 |
1986年 | 37篇 |
1985年 | 39篇 |
1984年 | 31篇 |
1983年 | 21篇 |
1982年 | 18篇 |
1981年 | 19篇 |
1979年 | 17篇 |
1978年 | 14篇 |
1977年 | 18篇 |
1976年 | 15篇 |
1975年 | 22篇 |
1974年 | 18篇 |
1973年 | 20篇 |
1969年 | 14篇 |
排序方式: 共有2580条查询结果,搜索用时 15 毫秒
21.
A genetic linkage map for zebrafish: comparative analysis and localization of genes and expressed sequences 下载免费PDF全文
Gates MA Kim L Egan ES Cardozo T Sirotkin HI Dougan ST Lashkari D Abagyan R Schier AF Talbot WS 《Genome research》1999,9(4):334-347
Genetic screens in zebrafish (Danio rerio) have isolated mutations in hundreds of genes with essential functions. To facilitate the identification of candidate genes for these mutations, we have genetically mapped 104 genes and expressed sequence tags by scoring single-strand conformational polymorphisms in a panel of haploid siblings. To integrate this map with existing genetic maps, we also scored 275 previously mapped genes, microsatellites, and sequence-tagged sites in the same haploid panel. Systematic phylogenetic analysis defined likely mammalian orthologs of mapped zebrafish genes, and comparison of map positions in zebrafish and mammals identified significant conservation of synteny. This comparative analysis also identified pairs of zebrafish genes that appear to be orthologous to single mammalian genes, suggesting that these genes arose in a genome duplication that occurred in the teleost lineage after the divergence of fish and mammal ancestors. This comparative map analysis will be useful in predicting the locations of zebrafish genes from mammalian gene maps and in understanding the evolution of the vertebrate genome. 相似文献
22.
23.
Characterization of a gene encoding survival motor neuron (SMN)-related protein, a constituent of the spliceosome complex 总被引:2,自引:3,他引:2
Talbot K; Miguel-Aliaga I; Mohaghegh P; Ponting CP; Davies KE 《Human molecular genetics》1998,7(13):2149-2156
Mutations in the gene encoding the Survival Motor Neuron (SMN) protein are
responsible for autosomal recessive proximal spinal muscular atrophy (SMA).
SMN orthologues have been identified in the nematode worm Caenorhabditis
elegans and the yeast Schizosaccharomyces pombe but, to date, no human
paralogues have been described. Here we describe identification and
characterization of an SMN-related protein (SMNrp) gene that encodes a
novel protein of 239 amino acids, which has recently been identified as a
constituent of the spliceosome complex and designated SPF30. Significant
similarity to the SMN protein is apparent only within a central region of
SMNrp that represents a tudor domain. The SMNrp/SPF30 gene has been mapped
to chromosome 10q23. It is differentially expressed, with abundant levels
in skeletal muscle. An exclusively nuclear localization for SMNrp in
cultured cells and muscle sections was revealed using GFP fusion constructs
and thereafter confirmed with a polyclonal antibody raised against SMNrp.
Overexpression of SMNrp as a fusion protein in HeLa cells in culture
induced dose-dependent apoptosis with positive TUNEL staining. In addition
to a possible role for this protein as a pro-apoptotic factor, SMN and its
related protein share significant similarities in sequence and cellular
function.
相似文献
24.
Changes in E-cadherin immunoreactivity in the adenoma-carcinoma sequence of the large bowel 总被引:7,自引:0,他引:7
Giuseppe Gagliardi Olcay Kandemir Michelle Guida Serena Benvestito Gordon W. H. Stamp Massimo Pignatelli Theo G. M. Ruers Irving S. Benjamin John M. A Northover Ian C. Talbot 《Virchows Archiv : an international journal of pathology》1995,426(2):149-154
We have used an avidin-biotin immunoperoxidase technique to localise epithelial cadherin (E-cadherin), a calcium-dependent cell-cell adhesion molecule, in 107 paraffin-embedded sections from 93 patients consisting of 24 with colorectal adenoma, 55 with rectal carcinoma and 14 with liver metastases. The corresponding primary colorectal tumours were also studied in these cases. E-cadherin was expressed by normal colorectal epithelial cells with typical membranous staining at the intercellular junctions. Loss of normal membranous E-cadherin expression and presence of cytoplasmic staining were found frequently in adenomas larger than 1 cm (P<0.01), with high grade dysplasia and villous histology (P<0.01). In primary rectal cancers, loss of membranous expression correlated with high tumour grade. No correlation was seen with Dukes and Jass stage, local extramural spread and 5-year recurrence rate. Complete loss of membranous E-cadherin immunoreactivity was seen in 7/14 (50%) liver metastases in which 6/7 (86%) showed intense membranous E-cadherin immunoreactivity in the corresponding primary tumour. Our data indicate that changes in E-cadherin immunoreactivity and cellular localisation correlate with size, severe dysplasia in adenomas and tumour grade in carcinomas. However, there seems to be no correlation between loss of membranous E-cadherin immunoreactivity and the invasive and metastatic potential of the carcinomas. 相似文献
25.
26.
27.
A case of signet-ring cell lymphoma affecting bone marrow is reported. The tumour presented as multiple lytic lesions in the lumbosacral spine. A bone biopsy specimen showed the typical appearances of signet-ring cell lymphoma, and the cells stained positively with antiserum to CD20, though neither immunoglobulin light or heavy chains could be shown within the vacuoles. The patient subsequently responded to chemotherapy. 相似文献
28.
Balanos GM Talbot NP Robbins PA Dorrington KL 《Pflügers Archiv : European journal of physiology》2005,450(6):372-380
In healthy humans, changes in cardiac output are commonly accommodated with minimal change in pulmonary artery pressure. Conversely, exposure to hypoxia is associated with substantial increases in pulmonary artery pressure. In this study we used non-invasive measurement of an index of pulmonary artery pressure, the maximum systolic pressure difference across the tricuspid valve (Pmax), to examine the pulmonary vascular response to changes in blood flow during both air breathing and hypoxia. We used Doppler echocardiography in 33 resting healthy humans breathing air over 6–24 h to measure spontaneous diurnal variations in Pmax and cardiac output. Cardiac output varied by up to ~2.5 l/min; Pmax varied little with cardiac output [0.61±0.74 (SD) mmHg min l–1]. Eight of the volunteers were also exposed to eucapnic hypoxia (end-tidal
) for 8 h. In this group Pmax rose progressively from 21 mmHg to 37 mmHg over 8 h. By comparing diurnal variations in Pmax during air breathing with changes in Pmax during hypoxia in the same eight individuals, we concluded that only approximately 5% of the changes in Pmax during hypoxia could be attributed to concurrent changes in cardiac output. The low sensitivity of Pmax to changes in cardiac output makes it a useful index of hypoxic pulmonary vasoconstriction in healthy humans. 相似文献
29.
Paul Workman Richard A. S. White Kathleen Talbot 《Cancer chemotherapy and pharmacology》1986,16(1):1-8
Summary Although it has been the subject of considerable interest for 15 years, originally as a cytotoxic agent and more recently as a radiosensitizer, there is very little pharmacokinetic information on CB 1954 (2,4-dinitro-5-aziridinylbenzamide). We have developed a rapid high-performance liquid chromatography assay for the drug and its metabolites and applied it to detailed examination of the pharmacokinetics of CB 1954 in mice and dogs. With IV administration a dose of 50 mg/kg gave peak blood concentrations of 100 g/ml in mice, while 25 mg/kg gave peak palsma concentrations of 27 g/ml in dogs. Peak concentrations were 3 to 5-fold lower for the IP route in mice and the oral route in dogs, and the bioavailabilities were 85% and 40%, respectively. Elimination t1/2 values were 1.4–2 h in mice and 2.5–4 h in dogs and were independent of route of administration. Plasma protein binding was 57% but tissue penetration in mice was generally good. Tumour: plasma ratios were 50%–90%, while brain: plasma ratios were lower, at 37%–50%. The parent drug and several metabolites were identified and quantified in mouse urine, the total recovery being 24%–29%, of which 16%–25% was parent drug. The metabolites were also found in the circulation and in tissues. No changes in pharmacokinetics were seen with repeated dosing in mice or with administration of the protective agent phenyl AIC. Phenobarbitone pretreatment produced a small reduction in elimination t1/2, mainly by accelerating aziridine ring removal. Allopurinol increased the blood levels of the 5-amino nitroreduction product. These studies provide a pharmacokinetic basis for interpreting the antitumour activity and toxicity of CB 1954, as well as for the development of new mixed-function sensitizers. 相似文献