全文获取类型
收费全文 | 240篇 |
免费 | 18篇 |
国内免费 | 27篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 19篇 |
妇产科学 | 3篇 |
基础医学 | 30篇 |
口腔科学 | 18篇 |
临床医学 | 44篇 |
内科学 | 59篇 |
皮肤病学 | 8篇 |
神经病学 | 3篇 |
特种医学 | 25篇 |
外科学 | 20篇 |
综合类 | 18篇 |
预防医学 | 7篇 |
药学 | 14篇 |
中国医学 | 1篇 |
肿瘤学 | 15篇 |
出版年
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 12篇 |
2012年 | 3篇 |
2011年 | 3篇 |
2010年 | 10篇 |
2009年 | 10篇 |
2008年 | 5篇 |
2007年 | 11篇 |
2006年 | 5篇 |
2005年 | 13篇 |
2004年 | 4篇 |
2003年 | 1篇 |
2002年 | 7篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1999年 | 8篇 |
1998年 | 21篇 |
1997年 | 18篇 |
1996年 | 17篇 |
1995年 | 13篇 |
1994年 | 14篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 10篇 |
1985年 | 4篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 3篇 |
排序方式: 共有285条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
85.
86.
目的:研究Down’s 综合征动物模型trisomy 16 结肠神经系发育和先天性巨结肠(HD) 病变肠管蛋白基因产物9-5(protein gene product9 .5 ,PGP9-5) 的神经表达。方法:Trisomy 16 鼠培育;细胞遗传学分析;Trisomy 16 鼠结肠和HDPGP9-5 免疫组织化学。结果:(1)Trisomy 16 鼠结肠神经系发育异常,肌间神经丛发育迟缓,粘膜下神经丛缺失,结肠末端有5 mm 的无神经节区,但结肠系膜神经发育良好;(2)HD狭窄段肠管PGP9-5 阳性神经纤维大量增生,神经节细胞缺如。结论:(1)Trisomy 16 鼠具有稳定的遗传学特征,可能伴先天性巨结肠。(2) 由于HD 狭窄段肠管神经节细胞缺失,增生的PGP9-5 阳性神经纤维是肠道外源性神经的代偿,对其神经元的性质尚有待确定。(3)HD有遗传倾向 相似文献
87.
Esaú P Santos Danielle RR Cavalcante Allan UC Melo José C Pereira Margarete Z Gomes Ricardo LC Albuquerque Jr 《Head & face medicine》2011,7(1):1-6
Extracorporeal formation of mineralized bone-like tissue is still an unsolved challenge in tissue engineering. Embryonic stem cells may open up new therapeutic options for the future and should be an interesting model for the analysis of fetal organogenesis. Here we describe a technique for culturing embryonic stem cells (ESCs) in the absence of artificial scaffolds which generated mineralized miromasses. Embryonic stem cells were harvested and osteogenic differentiation was stimulated by the addition of dexamethasone, ascorbic acid, and ß-glycerolphosphate (DAG). After three days of cultivation microspheres were formed. These spherical three-dimensional cell units showed a peripheral zone consisting of densely packed cell layers surrounded by minerals that were embedded in the extracellular matrix. Alizarine red staining confirmed evidence of mineralization after 10 days of DAG stimulation in the stimulated but not in the control group. Transmission electron microscopy demonstrated scorching crystallites and collagenous fibrils as early indication of bone formation. These extracellular structures resembled hydroxyl apatite-like crystals as demonstrated by distinct diffraction patterns using electron diffraction analysis. The micromass culture technique is an appropriate model to form three-dimensional bone-like micro-units without the need for an underlying scaffold. Further studies will have to show whether the technique is applicable also to pluripotent stem cells of different origin. 相似文献
88.
七月盛夏,宝岛台湾却惬意非常!浙江卫视女主播朱丹带领许多媒体朋友一同到南台湾做了一个很特别的美丽之旅,这一次,胶原蛋白不仅可以喝,还能被“看”出来。 相似文献
89.
The degradation of fibrillar type II collagen is a major feature of
cartilage destruction in rheumatoid arthritis (RA). Since collagenase 3 is
produced by chondrocytes and preferentially degrades type II cartilage
collagen, it seemed likely that this enzyme would have a prominent role in
the destruction of rheumatoid joints. Using immunolocalization techniques,
we have examined and compared the production and distributions of
collagenase 1 and collagenase 3 in cells and tissues derived from
rheumatoid knee arthroplasties. Primary cultures of chondrocytes stimulated
with interleukin-1 beta showed that most of the cells produced collagenase
1, whereas only a minority (approximately 5-10%) produced collagenase 3; a
few chondrocytes demonstrated the co-ordinate production of both enzymes.
Primary cultures of rheumatoid synoviocytes produced collagenase 1, but not
collagenase 3. Both enzymes were demonstrated in the rheumatoid lesion.
Collagenase 1 was more commonly observed in both synovium and cartilage (22
of the 28 specimens), was especially prominent at cartilage erosion sites,
and most of the positive specimens demonstrated extracellular enzyme. By
contrast, collagenase 3 was observed less frequently (7/28 specimens) and
was produced by relatively few chondrocytes and synovial cells, this
usually being much less than that observed for chondrocytes of
osteoarthritic cartilage. These observations suggest different regulatory
mechanisms for the production of collagenases 1 and 3 in the rheumatoid
lesion, and demonstrate that the distribution and production of collagenase
1 are far more prevalent than those for collagenase 3.
相似文献
90.
Hereditary hemolytic anemia caused by diverse point mutations of pyruvate kinase gene found in Japan and Hong Kong 总被引:2,自引:1,他引:1
Kanno H; Wei DC; Chan LC; Mizoguchi H; Ando M; Nakahata T; Narisawa K; Fujii H; Miwa S 《Blood》1994,84(10):3505-3509
We identified four distinct point mutations in homozygous pyruvate kinase (PK) variants in Japanese and Chinese patients with chronic nonspherocytic hemolytic anemia. All gene abnormalities were missense mutations that caused single amino acid substitutions. 1261A (Q421K) and 1436A (R436H), which were identified in PK Sendai and PK Shinshu, had been found in unrelated Japanese and Amish PK variants, respectively. The clinical severity and extremely low residual erythrocyte PK activity of PK Shinshu as well as of the Amish PK might be caused partly by aberrant splicing, because the 1436A mutation changes a nucleotide at the last nucleotide in the exon 10. Recently, we diagnosed a 42-year-old Japanese woman with chronic nonspherocytic hemolytic anemia as having a homozygous PK deficiency. DNA sequencing of the variant PK gene showed a homozygous missense mutation at 1403GCT- ->GTT, resulting in a single amino acid substitution from 468la-->Val. The gene mutation is likely to impair the allostericity of this enzyme, speculated from the tertiary structure. A homozygous missense mutation in PK Hong Kong, a boy of a non-Han southern Chinese minority group, was identified in exon 7 of the human L-PK gene, 941ATT-->ACT, resulting in a single amino acid substitution from 314lle-->Thr. The R- PK activity is expected to be severely affected, because the mutated amino acid residue is located between the 313 Lys and the 315 Glu, which are very important for acid-base catalysis and magnesium binding, respectively. Both the R- and M2-type PK were shown by polyacrylamide gel electrophoresis of the PK Hong Kong erythrocyte lysate, and this is the first report of a homozygous individual whose erythrocytes contain the immature (M2)-type isozyme. 相似文献