全文获取类型
收费全文 | 364篇 |
免费 | 14篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 18篇 |
儿科学 | 37篇 |
妇产科学 | 5篇 |
基础医学 | 52篇 |
口腔科学 | 9篇 |
临床医学 | 57篇 |
内科学 | 53篇 |
皮肤病学 | 4篇 |
神经病学 | 8篇 |
特种医学 | 28篇 |
外科学 | 34篇 |
综合类 | 24篇 |
预防医学 | 15篇 |
眼科学 | 1篇 |
药学 | 16篇 |
中国医学 | 4篇 |
肿瘤学 | 14篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 6篇 |
2017年 | 3篇 |
2015年 | 6篇 |
2014年 | 25篇 |
2013年 | 22篇 |
2012年 | 14篇 |
2011年 | 11篇 |
2010年 | 12篇 |
2009年 | 15篇 |
2008年 | 3篇 |
2007年 | 13篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 11篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 19篇 |
1999年 | 9篇 |
1998年 | 18篇 |
1997年 | 20篇 |
1996年 | 13篇 |
1995年 | 12篇 |
1994年 | 12篇 |
1993年 | 12篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1970年 | 1篇 |
1958年 | 1篇 |
1957年 | 2篇 |
1956年 | 2篇 |
1954年 | 2篇 |
1952年 | 16篇 |
1951年 | 23篇 |
1950年 | 2篇 |
排序方式: 共有379条查询结果,搜索用时 15 毫秒
1.
用体外培养的人的伪表皮作为模型,进行药物毒理学作用的研究,观察了二甲亚砜(DMSO)在不同浓度和不同接触时间条件下,对人的伪表皮细胞脱氧核糖核酸(DNA)、核糖核酸(RNA)和蛋白质合成的影响:随着接触时间的延长,DNA、RNA和蛋白质合成均受抑制。低浓度条件下(1%),DNA、RNA和蛋白质合成增加;在15~50%浓度下,DNA和蛋白质合成抑制,而RNA合成仍增加;在高浓度条件下(70%~100%),DNA、RNA和蛋白质合成均明显抑制。 相似文献
2.
3.
4.
Telfer JF; Thomson AJ; Cameron IT; Greer IA; Norman JE 《Human reproduction (Oxford, England)》1997,12(10):2306-2312
Superoxide, an agent which attenuates the half-life of nitric oxide, is
metabolized and synthesized by superoxide dismutase (SOD) and xanthine
oxidase, respectively. Over the last few years much work has focused on the
role of nitric oxide in human parturition. The aim of this study was to
determine whether the onset of human parturition is associated with a
change in the expression of copper/zinc superoxide dismutase (Cu/Zn SOD),
manganese superoxide dismutase (Mn SOD) or xanthine oxidase within the
uterus. Samples of myometrium, placenta, decidua and fetal membranes were
obtained from women before and after the onset of labour at term.
Immunocytochemistry was used to localize Cu/Zn SOD, Mn SOD and xanthine
oxidase and measure SOD enzyme activity. Cu/Zn and Mn SOD-like
immunoreactivity was detected in syncytiotrophoblast cells, villous stromal
cells and endothelial cells of blood vessels in the placenta. In the
myometrium Cu/Zn and Mn SOD were localized to myocytes and endothelial
cells and to some vascular smooth muscle cells. In the fetal membranes we
observed staining for Cu/Zn SOD and Mn SOD in the amnion, chorion,
extravillous trophoblast and decidua. There was no difference in SOD enzyme
activity or staining intensity for SOD between different cell types before
and during labour. Xanthine oxidase immunoreactivity was identified in each
of the tissues examined and again there was no difference in immunostaining
in tissues obtained from women delivered before or after the onset of
labour. These results show that the pregnant uterus is capable of both
synthesizing and degrading superoxide and suggest that superoxide dismutase
and xanthine oxidase may play a role in the maintenance of uterine
quiescence during pregnancy, but not in the initiation of parturition.
相似文献
5.
Pre-eclampsia, one of the most significant health problems inhuman pregnancy, complicates 6-7% of all gestations and is theleading cause of fetal growth retardation, infant morbidityand mortality, premature birth and maternal death. Recent researchimplicates free radicals in the pathophysiology of pre-eclampsia.This review covers the biochemistry of nitric oxide (NO) andpossible interactions with other free radicals. Studies in therat show that pregnancy is associated with enhanced productionand responsiveness to NO in both reproductive tissues and bloodvessels. Rats infused with NG-nitro-L-arginine methyl ester(L-NAME, a NO synthase inhibitor) have been used as an animalmodel of pre-eclampsia, and the effects of steroid hormoneson blood pressure in this model have been tested. Results suggestthat pre-eclampsia may be a state of NO deficiency. However,in humans there seem to be contradictions regarding the involvementof NO in maternal adaptation to pregnancy. It is suggested thatNO may be one of several systems that act in concert to maintaina symbiotic relationship between mother and fetus. However,the input of each system may be genetically determined. 相似文献
6.
Lubensky IA Schiffmann R Goldin E Tsokos M 《The American journal of surgical pathology》1999,23(12):1527-1531
Mucolipidosis type IV (ML-IV) is an autosomal recessive lysosomal storage disease that causes severe neurologic abnormalities. The brain disease is characterized by pigmented cytoplasmic granules in neurons and accumulation of lamellated membrane structures in lysosomes. The gastrointestinal disease in ML-IV was not previously recognized. Clinical examination of 20 patients with ML-IV (age range, 2-23 years) at the National Institutes of Health showed hypergastrinemia and constitutive achlorhydria. Endoscopic biopsy specimens from the gastric fundus, body, and antrum and from the duodenum of four such patients (ages 4, 6, 7, and 22 years) were evaluated histologically and by electron microscopy. Histologically, all gastric fundus and body biopsy specimens showed parietal cells in normal numbers. However, a striking cytoplasmic vacuolization of parietal cells was seen on hematoxylin and eosin stain. Electron microscopy showed the parietal cells to be markedly distended by large lysosomes containing lamellar, concentric, and cystic membranous inclusions. Additionally, chronic atrophic gastritis and enterochromaffin-like (ECL) cell hyperplasia were observed. Foveolar and chief cells in stomach and duodenum biopsy specimens were normal. We conclude that the cytoplasmic lysosomal inclusions in gastric parietal cells is a unique histologic feature of gastric biopsy in ML-IV. 相似文献
7.
散发内淋巴囊瘤VHL基因位点微卫星标志杂合性丢失的研究 总被引:1,自引:0,他引:1
目的 探讨散发内淋巴囊瘤发病与VHL基因异常之间的关系。方法 采用组织微切割技术和多聚酶链式反应等方法对3例散发内淋巴囊瘤肿瘤细胞VHL基因位点染色体微卫星标志的杂合性丢失进行分析。结果 3例散发内淋巴囊瘤中有2例发生VHL基因位点微卫星标志的杂合性丢失,进一步的研究证实,该两例肿瘤细胞中分别存在着VHL基因第二外显子的异常。结论 VHL基因的异常导致其功能改变不但是VHL的致病原因,而且是散发性内淋巴囊瘤发病的重要的基因遗传学基础。 相似文献
8.
BA Evans IA Hughes CL Bevan MN Patterson JW Gregory 《Archives of disease in childhood》1997,76(6):529-531
The androgen insensitivity syndrome is a heterogeneous disorder with a wide spectrum of phenotypic abnormalities, ranging from complete female to ambiguous forms that more closely resemble males. The primary abnormality is a defective androgen receptor protein due to a mutation of the androgen receptor gene. This prevents normal androgen action and thus leads to impaired virilisation. A point mutation of the androgen receptor gene affecting two siblings with partial androgen insensitivity syndrome is described. One had cliteromegaly and labial fusion and was raised as a girl, whereas the other sibling had micropenis and penoscrotal hypospadias and was raised as a boy. Both were shown to have the arginine 840 to cysteine mutation. The phenotypic variation in this family is thus dependent on factors other than abnormalities of the androgen receptor gene alone. 相似文献
9.
Ornstein DK Lubensky IA Venzon D Zbar B Linehan WM Walther MM 《The Journal of urology》2000,163(2):431-433
PURPOSE: We describe the earliest renal lesions associated with hereditary papillary renal cancer and estimate the prevalence of microscopic papillary renal tumors. MATERIALS AND METHODS: Grossly normal tissue was obtained from 12 kidneys during renal surgery in 9 patients with hereditary papillary renal cancer. Tissue was examined microscopically and findings were compared to those previously reported to be associated with von Hippel-Lindau disease and sporadic renal cell carcinoma. RESULTS: A total of 92 microscopic papillary renal cell carcinoma lesions were identified on 46 of 88 slides (53%). No other lesions were identified. All tumors were solid and displayed the basophilic papillary histology characteristic of hereditary papillary renal cancer. Extrapolation of the data predicted the prevalence of 1,100 to 3,400 microscopic papillary tumors in a single kidney in a patient with hereditary papillary renal cancer. CONCLUSIONS: The basophilic papillary histology characteristic of clinically apparent renal tumors in patients with hereditary papillary renal cancer also characterizes the multiple microscopic lesions seen in the kidneys. These findings suggest that the earliest renal tumor in patients with an activating hereditary mutation of the met gene is papillary basophilic renal cancer. The large number of microscopic tumors in patients with hereditary papillary renal cancer was comparable to or greater than that seen in those with von Hippel-Lindau disease. 相似文献
10.