全文获取类型
收费全文 | 536篇 |
免费 | 25篇 |
国内免费 | 12篇 |
专业分类
儿科学 | 41篇 |
妇产科学 | 5篇 |
基础医学 | 52篇 |
口腔科学 | 10篇 |
临床医学 | 54篇 |
内科学 | 176篇 |
皮肤病学 | 5篇 |
神经病学 | 35篇 |
特种医学 | 70篇 |
外科学 | 28篇 |
综合类 | 20篇 |
预防医学 | 16篇 |
药学 | 40篇 |
肿瘤学 | 21篇 |
出版年
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 11篇 |
2016年 | 6篇 |
2015年 | 6篇 |
2014年 | 19篇 |
2013年 | 18篇 |
2012年 | 19篇 |
2011年 | 10篇 |
2010年 | 24篇 |
2009年 | 16篇 |
2008年 | 10篇 |
2007年 | 10篇 |
2006年 | 22篇 |
2005年 | 13篇 |
2004年 | 10篇 |
2003年 | 18篇 |
2002年 | 3篇 |
2001年 | 12篇 |
2000年 | 10篇 |
1999年 | 18篇 |
1998年 | 29篇 |
1997年 | 19篇 |
1996年 | 23篇 |
1995年 | 17篇 |
1994年 | 17篇 |
1993年 | 13篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 13篇 |
1988年 | 9篇 |
1987年 | 10篇 |
1986年 | 17篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 8篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1973年 | 8篇 |
1972年 | 6篇 |
1943年 | 1篇 |
排序方式: 共有573条查询结果,搜索用时 31 毫秒
181.
182.
The induction of loss of heterozygosity (LOH) by the environmental
carcinogen N-nitrosodimethylamine (NDMA), and the factors that influence
the recovery of LOH mutations were studied in two directly related human
lymphoblastoid cell lines, AHH-1 (h2E1.v2) and MCL-5. Initially, the
NDMA-induced mutation frequency at the heterozygous tk locus in AHH-1 cells
was observed to be 5-fold higher in AHH-1 compared with MCL-5. Molecular
analysis of NDMA-induced TK- mutants indicated that the induced mutant
fraction attributable to small intragenic mutations was similar in both
cell lines. However, the induced mutant fraction, because of LOH, was
18-fold greater in AHH-1. In addition, LOH mutations were more extensive
among TK- mutants derived from AHH-1 cells. We hypothesized that the
increased recovery of large LOH mutations in AHH-1 cells could be
attributable to reduced apoptotic capacity, as it has been reported that
AHH-1 cells carry a heterozygous mutation in the p53 locus, whereas MCL-5
cells are homozygous wild- type. Analysis of the kinetics of apoptosis
showed that the apoptotic response of the AHH-1 cell line was diminished
and delayed compared with MCL-5. Based on the analyses presented here, and
several recent reports, it is suggested that the recovery of LOH mutations
in p53 deficient cell lines is affected not only by abnormalities in
cellular apoptotic response, but also involves a number of p53-mediated
responses to DNA damage.
相似文献
183.
184.
PM Macey RPK Ford PJ Brown J Larkin WR Fright KL Garden 《Acta paediatrica (Oslo, Norway : 1992)》1995,84(10):1103-1107
We examined the consistency of apnoea recognition between three human experts. The hypothesis was that computer detection of apnoea could emulate human expert apnoea recognition. The aim was to detect apnoeas with the highest possible accuracy from a single breathing signal, by both human experts and computer. Three human experts independently examined recordings of breathing waveform from overnight sleep studies from 10 infants aged 3-17 weeks. All apnoeas of 5 s or more were identified and reviewed. However, there still remained 10% disagreement. A computer apnoea detector was implemented. An algorithm analysed statistical properties of the signal to find breathing pauses. Optimal performance was 1 % missed apnoeas (compared with the agreed apnoeas identified by the three experts) and 29% false detections. This computer algorithm reliably identified most apnoeas but did not replace the human expert. Algorithm, apnoea, breathing, detection, expert 相似文献
185.
Hereditary lymphedema: evidence for linkage and genetic heterogeneity 总被引:10,自引:0,他引:10
Ferrell RE; Levinson KL; Esman JH; Kimak MA; Lawrence EC; Barmada MM; Finegold DN 《Human molecular genetics》1998,7(13):2073-2078
Hereditary or primary lymphedema is a developmental disorder of the
lymphatic system which leads to a disabling and disfiguring swelling of the
extremities. Hereditary lymphedema generally shows an autosomal dominant
pattern of inheritance with reduced penetrance, variable expression and
variable age at onset. Three multigeneration families demonstrating the
phenotype of hereditary lymphedema segregating as an autosomal dominant
trait with incomplete penetrance were genotyped for 366 autosomal markers.
Linkage analysis yielded a two-point LOD score of 6.1 at straight theta =
0. 0 for marker D5S1354 and a maximum multipoint LOD score of 8.8 at marker
D5S1354 located at chromosome 5q34-q35. Linkage analysis in two additional
families using markers from the linked region showed one family consistent
for linkage to distal chromosome 5. In the second family, linkage to 5q was
excluded for all markers in the region with LOD scores Z < -2.0. The
vascular endothelial growth factor C receptor ( FLT4 ) was mapped to the
linked region, and partial sequence analysis identified a G-->A
transition at nucleotide position 3360 of the FLT4 cDNA, predicting a
leucine for proline substitution at residue 1126 of the mature receptor in
one nuclear family. This study localizes a gene for primary lymphedema to
distal chromosome 5q, identifies a plausible candidate gene in the linked
region, and provides evidence for a second, unlinked locus for primary
lymphedema.
相似文献
186.
M.Noar L Xu KL Koch 《基础医学与临床》2003,23(Z1):56
目的明确在合并GERD和消化不良的患者(GERD+)中进行食管下段括约肌/贲门区的射频消融术(RFA)治疗对胃肌电活动及胃容量的影响.
方法于因GI疾病就诊的人群中选出45名难治性GERD患者(32名女性,13名男性,年龄:19-78岁),在进行RFA(Stretta procedure)之前,接受内镜及胃电图(EGG)-水负荷(WLT)试验:内镜显示为1级食管炎或正常黏膜;EGG-WLT采用标准方法检测,并且根据EGG节律带基线和计算机分析做出诊断(胃动过缓、胃动过速、混合型节律失常或正常). 相似文献
187.
KL SAMPATH KUMAR 《Medical Journal Armed Forces India》1999,55(4):371-372
188.
189.
目的 探讨地塞米松与三磷酸腺苷(ATP)联用在体外诱导细粒棘球绦虫原头节细胞凋亡的作用。 方法 体外培养细粒棘球绦虫原头节,分别设地塞米松(5 mmol/L)组、 ATP(1.6 mmol/L)组、 地塞米松(5 mmol/L)+ATP(1.6 mmol/L)组和空白对照组,显微镜下观察原头节变化。药物诱导8 h后,选取原头节形态改变最明显的一组和空白对照组,透射电镜观察这两组原头节的超微结构,原位末端脱氧核糖核苷酸转移酶标记技术(TUNEL法)检测原头节中的凋亡细胞,半胱氨酸天冬氨酸蛋白酶-3(caspase-3)活性检测试剂盒检测该酶活性,琼脂糖凝胶电泳检测两组原头节的DNA片段。 结果 药物诱导8 h后观察,与对照组相比,地塞米松组和地塞米松+ATP组的原头节均出现团缩、顶突内凹和体积缩小,钙颗粒明显减少且模糊不清,未见原头节活动,其中地塞米松+ATP组原头节的形态改变更明显,故选择该组作为实验组,与空白对照组进行后续试验。透射电镜观察见实验组原头节中实质细胞体积缩小、细胞膜皱缩、细胞基质浓缩、核异染色质凝集呈团块状或新月形边集于核膜下,表现出凋亡细胞的特征。TUNEL法在实验组的原头节中检测到散在的凋亡细胞,对照组则未见凋亡细胞。实验组caspase-3活性约为对照组的12倍。电泳结果显示,实验组DNA中有约150 bp的核小体DNA片段。 结论 地塞米松与ATP联用可在体外诱导细粒棘球绦虫原头节细胞凋亡。 相似文献
190.