全文获取类型
收费全文 | 3947篇 |
免费 | 225篇 |
国内免费 | 50篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 112篇 |
妇产科学 | 26篇 |
基础医学 | 569篇 |
口腔科学 | 86篇 |
临床医学 | 244篇 |
内科学 | 1131篇 |
皮肤病学 | 22篇 |
神经病学 | 245篇 |
特种医学 | 180篇 |
外科学 | 720篇 |
综合类 | 19篇 |
预防医学 | 76篇 |
眼科学 | 22篇 |
药学 | 208篇 |
中国医学 | 6篇 |
肿瘤学 | 548篇 |
出版年
2023年 | 29篇 |
2022年 | 52篇 |
2021年 | 128篇 |
2020年 | 62篇 |
2019年 | 75篇 |
2018年 | 133篇 |
2017年 | 85篇 |
2016年 | 114篇 |
2015年 | 126篇 |
2014年 | 160篇 |
2013年 | 178篇 |
2012年 | 345篇 |
2011年 | 345篇 |
2010年 | 175篇 |
2009年 | 155篇 |
2008年 | 251篇 |
2007年 | 287篇 |
2006年 | 266篇 |
2005年 | 212篇 |
2004年 | 222篇 |
2003年 | 234篇 |
2002年 | 192篇 |
2001年 | 31篇 |
2000年 | 34篇 |
1999年 | 41篇 |
1998年 | 53篇 |
1997年 | 35篇 |
1996年 | 33篇 |
1995年 | 31篇 |
1994年 | 19篇 |
1993年 | 26篇 |
1992年 | 28篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1970年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有4222条查询结果,搜索用时 546 毫秒
31.
Yongchol Shin Atsushi Kitayama Tetsuya Koide Daniel A Peiffer Makoto Mochii Arnold Liao Naoto Ueno Ken W Y Cho 《Developmental dynamics》2005,232(2):432-444
To isolate novel genes regulating neural induction, we used a DNA microarray approach. As neural induction is thought to occur by means of the inhibition of bone morphogenetic protein (BMP) signaling, BMP signaling was inhibited in ectodermal cells by overexpression of a dominant-negative receptor. RNAs were isolated from control animal cap explants and from dominant-negative BMP receptor expressing animal caps and subjected to a microarray experiment using newly generated high-density Xenopus DNA microarray chips representing over 17,000 unigenes. We have identified 77 genes that are induced in animal caps after inhibition of BMP signaling, and all of these genes were subjected to whole-mount in situ hybridization analysis. Thirty-two genes showed specific expression in neural tissues. Of the 32, 14 genes have never been linked to neural induction. Two genes that are highly induced by BMP inhibition are inhibitors of Wnt signaling, suggesting that a key step in neural induction is to produce Wnt antagonists to promote anterior neural plate development. Our current analysis also proves that a microarray approach is useful in identifying novel candidate factors involved in neural induction and patterning. 相似文献
32.
Masahito Katoh Yasushi Itoh Kazumasa Ogasawara Kiichi Kajino Hiroki Nishihori Akio Takahashi Naoto Matsuki Kazuya Iwabuchi Takato O. Yoshida Robert A. Good Kazunori Ono 《European journal of immunology》1996,26(5):976-980
In a previous study, we identified T cell receptor and major histocompatibility complex (MHC) contact sites on the pigeon cytochrome c p43-58 peptide. Positions 46 and 54 of p43-58 were shown to be the MHC-binding sites. Specific amino acids were identified on the MHC-binding sites which bound to the relevant I-A molecule. In the present study, using NOD (I-Ag7) mice, we established a T cell hybridoma, NOE33-1-2, specific for a p43-58 analog 46R50E54A with arginine (R) and alanine (A) at positions 46 and 54, respectively. Interestingly, NOE 33-1-2 recognized 46R50E54A in the presence of not only I-Ag7, but also I-Ad, s, u and v. In contrast to previous reports that promiscuous T cells were able to recognize peptide antigens with various HLA-DR or I-E molecules consist of monomorphic α and polymorphic β chains, the promiscuous T cell clone NOE33-1-2 recognized peptides with various I-A molecules lacking the monomorphic chain. 相似文献
33.
Virus-like particles (VLPs, named HmTV1-17), about 40nm in diameter were found in the violet root rot fungus Helicobasidium mompa Tanaka strain No. 17, which had been isolated from an apple tree. Purified preparations of HmTV1-17 contained two species of double-stranded RNA (dsRNA), designated 17L and 17S. cDNAs were constructed from HmTV1-17 genomic dsRNAs purified using CF-11 cellulose column chromatography. The sequences of 17L and 17S cDNA comprised 5207 and 2096bp, respectively. Although 17S has no large open reading flame (ORF) on either strand, 17L has two large overlapping ORFs. The 5 located ORF1 encodes the coat protein (CP, 788 amino acids), whereas the gene product of ORF2, which is in the –1 frame relative to ORF1, shows the typical features of a RNA dependent RNA polymerase (RDRP, 845 amino acids). Phylogenetic analysis based on RDRP showed that HmTV1-17 is closely related to Sphaeropsis sapinea SsRV1, a member of the genus Totivirus from filamentous fungus S. sapinea. 相似文献
34.
35.
36.
目的 :测定类风湿性关节炎病人足底压 ,评价足底板的生物力学效应。方法 :12名女性类风湿性关节炎病人和 8名健康女性进行年龄和体重匹配。用 F- Scan系统进行动态足底压测量 ,Kistler床反力平台用以校正测量精确性。测量足底峰压和垂直分力 ,评价足底板的生物力学表现。结果 :类风湿性关节炎病人中足底压明显高于健康人。使用足底板后 ,足底总的峰压明显降低 ,前足、后足峰压减低 ,中足峰压增高。而垂直分力改变不大。结论 :足底板能显著降低足底压力 ,使足底压力重分布 ,减轻类风湿足痛。特殊设计的足底板对类风湿足痛的治疗能起重要的作用 相似文献
37.
Takanori Ito Taishi Takahara Natsuki Taniguchi Yuki Yamamoto Akira Satou Akiko Ohashi Emiko Takahashi Naoto Sassa Toyonori Tsuzuki 《Pathology international》2023,73(11):542-548
Clinical and genomic features of prostate cancer (PCa) vary considerably between Asian and Western populations. PTEN loss is the most frequent abnormality in intraductal carcinoma of the prostate (IDC-P) in Western populations. However, its prevalence and significance in Asian populations have not yet been well studied. In the present study, we evaluated PTEN expression in IDC-P in a Japanese population and its association with ERG expression. This study included 45 and 59 patients with PCa with and without IDC-P, respectively, who underwent radical prostatectomy. PTEN loss was observed in 10 patients with PCa with IDC-P (22%) and nine patients with PCa without IDC-P (17%). ERG expression was relatively frequent in patients with PCa with PTEN loss, although a significant difference was not observed. The co-occurrence of PTEN loss and ERG expression was observed in four patients with PCa with IDC-P and one without IDC-P. PTEN loss and ERG expression did not affect progression-free survival, regardless of the presence of IDC-P. The frequency of PTEN loss in IDC-P is lower in Asian patients than in Western patients. Our results indicate that mechanisms underlying IDC-P in Asian populations are different from those of Western populations. 相似文献
38.
Nomizu T Tsuchiya A Kanno M Katagata N Watanabe F Yamaki Y Abe R Miki Y 《Breast cancer (Tokyo, Japan)》1997,4(4):239-242
The possible role of germline mutations ofBRCA1 andBRCA2 as causative agents of familial breast cancer was assessed. Their possible involvement in the carcinogenesis of hereditary
breast cancer was investigated using 63 clinically suspect families. Twenty-one lineages (33.3%) had mutations in one of the
twoBRCA genes. This relatively low incidence suggested that germline mutations in unknown genes are involved in the carcinogenesis
of hereditary breast cancer in the Japanese population. However, the clinicopathological features characteristic of hereditary
breast cancer, such as early disease onset, a high incidence of bilateral breast cancer, and a high incidence of multiple
primary carcinomas in other organs were confirmed in the present study. 相似文献
39.
Moriya Hidetaka Maitani Yoshie Shimoda Naoto Takayama Kozo Nagai Tsuneji 《Pharmaceutical research》1997,14(11):1621-1628
Purpose. Recombinant human erythropoietin (Epo) is used frequently through intravenous (i.v.) and subcutaneous (s.c.) administration for the clinical treatment of the last stage of renal anemia. We encapsulated Epo in liposomes to develop an alternative administration route. The purpose of our study was to evaluate the pharmacokinetics and the pharmacological effects of liposomal Epo in comparison with the Epo after i.v. and s.c. administration to rats.
Methods. Epo was encapsulated in liposomes composed of dipalmitoylphosphatidylcholine (DPPC) and soybean-derived sterol mixture (SS) prepared by the reversed-phase evaporation vesicle method. After filtration through a 0.1 m polycarbonate membrane, liposomes were gel filtered (Epo/liposomes).
Results. Epo/liposomes showed higher pharmacological activity than Epo/liposomes before gel filtration after i.v. administration to rats. Non-encapsulated Epo lost its activity, whereas encapsulated Epo in liposomes retained it. The pharmacological effects of Epo/liposomes were greater than those of Epo after i.v. administration. Epo/liposomes afforded 3–9 times higher AUC, lower clearance and lower steady-state volume of distribution than Epo after both i.v. and s.c. administrations. Epo/liposomes had an improved pharmacokinetic profile compared with Epo. S.c. administration of Epo/liposomes at 7 h may penetrate primarily (40% of dose) through the blood as a liposome and partly (7% of dose) in lymph.
Conclusions. Epo/liposomes may reduce the frequency of injections required for a certain reticulocyte effect in comparison to Epo. The lower clearance of Epo/liposomes may increase the plasma concentrations of Epo, which increases the efficacy. 相似文献
40.
(Received for publication on Dec. 8, 1997; accepted on July 7, 1998) 相似文献