全文获取类型
收费全文 | 236935篇 |
免费 | 5823篇 |
国内免费 | 1762篇 |
专业分类
耳鼻咽喉 | 1960篇 |
儿科学 | 7758篇 |
妇产科学 | 5185篇 |
基础医学 | 24265篇 |
口腔科学 | 2690篇 |
临床医学 | 19046篇 |
内科学 | 42216篇 |
皮肤病学 | 1844篇 |
神经病学 | 20223篇 |
特种医学 | 11422篇 |
外国民族医学 | 6篇 |
外科学 | 36986篇 |
综合类 | 6537篇 |
现状与发展 | 7篇 |
一般理论 | 11篇 |
预防医学 | 21414篇 |
眼科学 | 4111篇 |
药学 | 14696篇 |
20篇 | |
中国医学 | 2337篇 |
肿瘤学 | 21786篇 |
出版年
2023年 | 537篇 |
2022年 | 1351篇 |
2021年 | 2177篇 |
2020年 | 1337篇 |
2019年 | 1639篇 |
2018年 | 23717篇 |
2017年 | 18755篇 |
2016年 | 20929篇 |
2015年 | 3222篇 |
2014年 | 3681篇 |
2013年 | 4123篇 |
2012年 | 11640篇 |
2011年 | 25420篇 |
2010年 | 21611篇 |
2009年 | 13994篇 |
2008年 | 22812篇 |
2007年 | 25015篇 |
2006年 | 3852篇 |
2005年 | 5210篇 |
2004年 | 6115篇 |
2003年 | 6952篇 |
2002年 | 4762篇 |
2001年 | 2108篇 |
2000年 | 2014篇 |
1999年 | 1493篇 |
1998年 | 748篇 |
1997年 | 659篇 |
1996年 | 506篇 |
1995年 | 476篇 |
1994年 | 444篇 |
1993年 | 297篇 |
1992年 | 746篇 |
1991年 | 664篇 |
1990年 | 651篇 |
1989年 | 557篇 |
1988年 | 471篇 |
1987年 | 461篇 |
1986年 | 376篇 |
1985年 | 323篇 |
1984年 | 247篇 |
1983年 | 211篇 |
1982年 | 138篇 |
1981年 | 122篇 |
1980年 | 138篇 |
1979年 | 207篇 |
1978年 | 169篇 |
1977年 | 106篇 |
1976年 | 118篇 |
1975年 | 107篇 |
1974年 | 115篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Wen-Ni Chang Jen-Ning Tsai Bing-Hung Chen Huei-Sheng Huang Tzu-Fun Fu 《Drug metabolism and disposition》2007,35(11):2127-2137
Serine hydroxymethyltransferase (SHMT) provides activated one-carbon units required for the biosynthesis of nucleotides, protein, and methyl group by converting serine and tetrahydrofolate to glycine and N(5),N(10)-methylenetetrahydrofolate. It is postulated that SHMT activity is associated with the development of methotrexate resistance and the in vivo activity of SHMT is regulated by the binding of N(5)-CHO-THF, the rescue agent in high-dose methotrexate chemotherapy. The aim of this study is to advance our understanding of the folate-mediated one-carbon metabolism in zebrafish by characterizing zebrafish mitochondrial SHMT. The cDNA encoding zebrafish mitochondrial SHMT was cloned, overexpressed in Escherichia coli, and purified with a three-step purification protocol. Similarities in structural, physical, and kinetic properties were revealed between the recombinant zebrafish mitochondrial SHMT and its mammalian orthologs. Surprisingly, leucovorin significantly inhibits the aldol cleavage of serine catalyzed by zebrafish cytosolic SHMT but inhibits to a lesser extent the reaction catalyzed by the mitochondrial isozyme. This is, to our knowledge, the first report on zebrafish mitochondrial folate enzyme as well as the differential inhibition of leucovorin on these two SHMT isoforms. Western blot analysis revealed tissue-specific distribution with the highest enrichment present in liver for both cytosolic and mitochondrial SHMTs. Intracellular localization was confirmed by confocal microscopy for both mitochondrial and cytosolic SHMTs. Unexpectedly, the cytosolic isoform was observed in both nucleus and cytosol. Together with the previous report on zebrafish cytosolic SHMT, we suggest that zSHMTs can be used in in vitro assays for folate-related investigation and antifolate drug discovery. 相似文献
102.
103.
Sergio Barroilhet Adrián Cano-Prous Salvador Cervera-Enguix Maria João Forjaz Francisco Guillén-Grima 《Social psychiatry and psychiatric epidemiology》2009,44(12):1051-1065
Introduction
This paper presents the results of a study on the psychometric properties of an authorized Spanish version of the McMaster Family Assessment Device, a self-report measure of family functioning. 相似文献104.
105.
106.
107.
Introduction
Although ependymoma is the third most common pediatric brain tumor, we know little about the genetic/epigenetic basis of its initiation, maintenance, or progression. This is due in part to the heterogeneity of the disease, as well as the small sample size of the cohorts analyzed in most studies. 相似文献108.
Peter Angelos 《World journal of surgery》2009,33(4):609-611
109.
Kentaroh Miyoshi Minoru Naito Tsuyoshi Ueno Shinji Hato Hideo Ino 《General thoracic and cardiovascular surgery》2009,57(11):629-632
A benign esophageal leiomyoma with abnormally increased fluorine-18-fluorodeoxyglucose uptake on positron emission tomography
(PET) was resected thoracoscopically. The tumor, of which the maximum standardized uptake value of the lesion was 4.7, was
well defined and 38 mm in diameter. Neither mitotic activity nor degeneration was found histologically; and immunoreactivity
for CD34, CD117, MIB-1, and glucose transporter-1 was negative immunohistochemically. A diagnosis of gastrointestinal stromal
tumor was ruled out by an oncogenic kinase gene mutation study. This case cautions against PET-dependent evaluation for malignant
potential of esophageal submucosal tumors. 相似文献
110.