全文获取类型
收费全文 | 698篇 |
免费 | 33篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 30篇 |
儿科学 | 49篇 |
妇产科学 | 7篇 |
基础医学 | 79篇 |
口腔科学 | 15篇 |
临床医学 | 96篇 |
内科学 | 69篇 |
皮肤病学 | 72篇 |
神经病学 | 16篇 |
特种医学 | 30篇 |
外科学 | 106篇 |
综合类 | 32篇 |
预防医学 | 24篇 |
眼科学 | 10篇 |
药学 | 57篇 |
中国医学 | 6篇 |
肿瘤学 | 34篇 |
出版年
2022年 | 6篇 |
2021年 | 15篇 |
2020年 | 10篇 |
2019年 | 14篇 |
2018年 | 12篇 |
2017年 | 14篇 |
2016年 | 13篇 |
2015年 | 19篇 |
2014年 | 43篇 |
2013年 | 50篇 |
2012年 | 52篇 |
2011年 | 59篇 |
2010年 | 31篇 |
2009年 | 24篇 |
2008年 | 22篇 |
2007年 | 37篇 |
2006年 | 28篇 |
2005年 | 21篇 |
2004年 | 20篇 |
2003年 | 29篇 |
2002年 | 21篇 |
2001年 | 5篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 18篇 |
1997年 | 18篇 |
1996年 | 13篇 |
1995年 | 10篇 |
1994年 | 10篇 |
1993年 | 15篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1987年 | 5篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976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732条查询结果,搜索用时 22 毫秒
1.
2.
Comparison of the Exposure Obtained by Endoscope and Microscope in the Extended Trans-Sphenoidal Approach 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Skull base》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Objective: Trans-sphenoidal surgery is often combined with other approaches for the treatment of middle cranial base tumors. By combining a maxillotomy with trans-sphenoidal approach, significantly wider exposure to these regions is gained. However, endoscope-assisted techniques have also been used for sellar and parasellar and upper clival regions. Methods: An extended trans-sphenoidal approach was performed on 10 cadaver heads using the operating microscope and was repeated with a 0-degree endoscope. The mean horizontal and vertical distances were measured and pictured for each technique, and both distances were compared using a parametric paired Student's t-test. Results: The mean horizontal distances in the 10 specimens were 19.5 ± 1.8 mm by microscope and 27.5 ± 2.2 mm by endoscope, and the mean vertical distances were 25.8 ± 1.9 mm by the microscope and 34.5 ± 3.5 mm by the endoscope. Conclusion: The aim of this study was to quantify the amount of exposure obtained with an extended trans-sphenoidal approach and to compare both endoscopic and microscopic techniques. Using the endoscope in conjunction with the operating microscope may provide additional exposure and better access in skull base surgery. 相似文献
3.
Microanatomy and surgical approaches to the infratemporal fossa: an anaglyphic three-dimensional stereoscopic printing study. 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《Skull base》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Objective: The infratemporal fossa (ITF) is a continuation of the temporal fossa between the internal surface of the zygoma and the external surface of the temporal bone and greater wing of the sphenoid bone that is sitting deep to the ramus of the mandible. The principal structure to understanding its relationships is the lateral pterygoid muscle. Other important structures are the medial pterygoid muscle, the maxillary artery, the pterygoid venous plexus, the otic ganglion, the chorda tympani nerve and the mandibular nerve. In this study, we describe the microsurgical anatomy of the ITF, as viewed by step-by-step anatomical dissection and also through the perspective of three lateral approaches and one anterior surgical approach. Methods: Eight cadaver specimens were dissected. In one side of all specimens, an anatomical dissection was done in which a wide preauricular incision from the neck on the anterior border of the sternoclidomastoid muscle at the level of the cricoid cartilage to the superior temporal line was made. The flap was displaced anteriorly and the structures of the neck were dissected followed by a zygomatic osteotomy and dissection of the ITF structures. On the other side were the surgical approaches to the ITF. The combined infratemporal and posterior fossa approach was done in two specimens, the subtemporal preauricular infratemporal fossa approach in two, the zygomatic approach in two, and the lateral transantral maxillotomy in two. The anatomical dissections were documented on the three-dimensional (3D) anaglyphic method to produce stereoscopic prints. Results: The lateral pterygoid muscle is one of the principal structures to enable understanding of the relationships into the ITF. The tendon of the temporal muscle inserts in the coronoid process at the ITF. The maxillary artery is the terminal branch of the external carotid artery that originates at the neck of the mandible and runs into the parotid gland. In our dissections the maxillary artery was lateral to the buccal, lingual, and inferior alveolar nerves. We found the second part of the maxillary artery superficial to the lateral pterygoid muscle in all specimens The anterior and posterior branches of the deep temporal artery supply the temporal muscle. In two cases we found a middle deep temporal artery. The different approaches that we used provided different views of the same anatomical landmarks and this provides not only safer surgery but also the best choice to approach the ITF according with the pathology extension. Conclusions: The ITF is a complex region on the skull base that is affected by benign and malignant tumors. The study through different routes is helpful to disclose the relationship among the anatomical structures. Although the authors have shown four approaches, there are a variety of approaches and even a combination of these can be used. This type of anatomical knowledge is essential to choosing the best approach to treat lesions in this area. 相似文献
4.
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
5.
6.
7.
8.
Sawyer JR Husain M Lukacs JL Stangeby C Binz RL Al-Mefty O 《Cancer Genetics and Cytogenetics》2003,145(1):38-48
Characteristic cytogenetic aberrations are found in the various histopathological designations of meningioma. These aberrations range from the loss of 22q in histologically benign tumors to complex hypodiploid karyotypes in atypical and malignant tumors. This progression is characterized by increasing chromosome loss and instability, with a critical step being the loss of 1p. We report a detailed cytogenetic investigation of chromosome aberrations in a series of 88 meningiomas using Giemsa banding and multicolor spectral karyotyping (SKY). Clonal chromosome aberrations were identified in 46 (52%) tumors by G banding. Thirty-five tumors showing complex chromosome aberrations not fully characterized by G banding were subsequently reanalyzed by SKY. The SKY technique refined the G-band findings in 18 (51%) of the tumors on which it was applied. The most common features of cytogenetic progression in the complex karyotypes were chromosome arm-specific losses relating to the formation of deletions and dicentric chromosomes involving 1p. Part or all of 1p was lost in 19 tumors. Five tumors showed evidence for the loss of 1p in a progressive step-wise series of telomeric fusions involving the formation of unstable intermediates. Five recurring dicentric chromosomes were identified, including dic (1;11)(p11;p11), dic(1;12)(p12 approximately p13;p11), dic(1;22)(p11;q12 approximately q13), dic(7;19)(p11;p11), and dic(19;22)(p11 approximately p13;q11 approximately q13). These findings provide evidence that telomeric fusions play a role in the formation of clonal deletions, dicentrics, and unbalanced translocations of 1p. The loss of 1p has possible diagnostic and prognostic implications in the management of meningioma. 相似文献
9.
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
10.
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