首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1430篇
  免费   71篇
  国内免费   8篇
耳鼻咽喉   32篇
儿科学   25篇
妇产科学   18篇
基础医学   98篇
口腔科学   21篇
临床医学   105篇
内科学   323篇
皮肤病学   19篇
神经病学   80篇
特种医学   126篇
外科学   412篇
综合类   35篇
一般理论   2篇
预防医学   45篇
眼科学   37篇
药学   50篇
中国医学   10篇
肿瘤学   71篇
  2024年   3篇
  2023年   15篇
  2022年   34篇
  2021年   46篇
  2020年   35篇
  2019年   72篇
  2018年   55篇
  2017年   30篇
  2016年   43篇
  2015年   39篇
  2014年   90篇
  2013年   78篇
  2012年   127篇
  2011年   122篇
  2010年   63篇
  2009年   31篇
  2008年   89篇
  2007年   120篇
  2006年   88篇
  2005年   80篇
  2004年   67篇
  2003年   58篇
  2002年   51篇
  2001年   8篇
  2000年   6篇
  1999年   10篇
  1998年   6篇
  1997年   5篇
  1996年   4篇
  1995年   4篇
  1994年   4篇
  1993年   1篇
  1992年   1篇
  1991年   2篇
  1989年   1篇
  1988年   4篇
  1987年   2篇
  1984年   1篇
  1983年   1篇
  1981年   3篇
  1980年   1篇
  1979年   2篇
  1975年   2篇
  1974年   2篇
  1973年   1篇
  1972年   1篇
  1964年   1篇
排序方式: 共有1509条查询结果,搜索用时 15 毫秒
991.
992.
A 13‐year‐old girl was referred to our dermatology outpatient clinic for the treatment of a congenital, circumscribed, hypertrichotic area on the lumbosacral region because it was cosmetically embarrassing. Dermatologic examination revealed a 25 × 15 cm circumscribed hypertrichotic area on the lumbosacral region. Coarse, dark, terminal hairs were observed, but the underlying skin was normal ( Fig. 1 ). The lesion had been present since birth. Her history also revealed back pain, which developed by 3 years of age, and a long history of urinary incontinence. On neurologic examination, no motor weakness or sensory changes were observed. On orthopedic examination, minimal atrophy and 2 cm shortening of the right leg were detected, and the right foot was smaller than the left. There was an accentuation of lumbar lordosis. There was no history of a similar lesion in the family. There was no consanguinity in the relatives.
Figure 1 Open in figure viewer PowerPoint Clinical appearance of the patient 6 months after operation  相似文献   
993.
Omics data address key issues in liver transplantation (LT) as the most effective therapeutic means for end-stage liver dis-ease. The purpose of this study was ...  相似文献   
994.
Neuroglobin: an endogenous neuroprotectant   总被引:2,自引:0,他引:2  
Cerebral hypoxia and ischemia trigger endogenous protective mechanisms that can prevent or limit brain damage. Understanding these mechanisms may lead to new therapeutic strategies for stroke and related disorders. Neuroglobin (Ngb), a recently discovered protein that is distantly related to hemoglobin and myoglobin, is expressed predominantly in brain neurons, and appears to modulate hypoxic-ischemic brain injury. Evidence includes the observations that neuronal hypoxia and cerebral ischemia induce Ngb expression, that enhancing Ngb expression reduces--and knocking down Ngb expression increases--hypoxic neuronal injury in vitro and ischemic cerebral injury in vivo, and that Ngb-overexpressing transgenic mice are resistant to cerebral infarction. However, the mechanisms that underlie hypoxic induction of Ngb and neuroprotection by Ngb are still unclear.  相似文献   
995.
Unreinforced masonry (URM) is one of the most popular construction materials around the world, but vulnerable during earthquakes. Due to its brittle nature, the URM structures may lead to a possible collapse of the wall of a building during earthquake events causing casualties. In the current research, an attempt is made to enhance the seismic capacity of URM structures by proposing a new innovative composite material that can improve the shear strength and deformation capacity of the URM wall systems. The results revealed that the fiber-reinforced plastic having high tensile and shear stiffness can significantly increase in-plane as well as out-of-plane bending strength of the URM wall. It was recorded that the bending moment of the prism increased up to 549.5% by increasing the bending moment from 490 N*mm to 3183 N*mm per mm deflection of prism upon using glass fibers. Moreover, the ductility ratio amplified up to 5.73 times while the stiffness ratio increased up to 4.16 times with the aid of glass fibers. Since the material used in this research work is low cost, easily available, and no need for any skilled labor, which is economically good. Therefore, the URM walls retrofitted with fiber-reinforced plastic is an economical solution.  相似文献   
996.
Malaria is one of the most common parasitic infection in India. The diagnosis largely depends on peripheral blood smear examination. Newer diagnostic methods like various antigen detection assays are now in use for prompt diagnosis and treatment. This study was done to determine the effectiveness of Diagnos Malaria Stix (antigen detection) assay in diagnosis of malaria. This involves detection of PfHRP-2 antigen and P.V. specific pLDH antigen. 162 patients with signs and symptoms of malaria included in the study. Leishman stained blood smear examination was done for all patients. Commercially available Diagnos Malaria Stix assay was used. Diagnos Malaria Stix showed sensitivity, specificity positive and negative predictive values of 100% each while Sensitivity, specificity, positive and negative predictive values of Leishman stained blood smear examination were 45.45%, 100%, 100% and 92% respectively.  相似文献   
997.
998.
Oxidative stress in hypertension   总被引:1,自引:0,他引:1  
Several experimental and clinical evidences have linked an enhanced production of reactive oxygen species (ROS) to certain diseases of the cardiovascular system including hypertension and diabetes. However, it has never been clearly established whether the enhanced oxidative stress observed in those conditions is primary or secondary to the pathological process. Our experimental studies have permitted to demonstrate that ROS, mainly through the production of superoxide anion, can cause important alterations in the cellular signal transduction systems characterized by an enhanced production of inositol triphosphate and a reduced production of cyclic GMP in cultured vascular smooth muscle cells (SMC), thus favouring the vasoconstriction. Since those effects were found to be increased in SMC from spontaneously hypertensive rats (SHR), this suggested a greater sensitivity of the vascular tissue of SHR to the oxidative stress. Moreover, we also have observed an increased production of superoxide anion in the aorta of rats made hypertensive according to the SHR, glucose or angiotensin-induced and DOCA-salt models during the development of hypertension. Since the superoxide anion production could be correlated with the level of blood pressure and since the development of hypertension could be either totally prevented or markedly attenuated by chronic treatment with potent antioxidative therapies such as alpha lipoic acid or aspirin, this suggested a major contribution of vascular superoxide anion production in the development of hypertension in those models. Moreover, the development of insulin resistance, which is associated to the model of glucose-induced hypertension, was also found to be prevented by chronic antioxidant therapies, thus suggesting that oxidative stress plays an important role as well in the development of insulin resistance and type 2 diabetes. In conclusion, it appears that oxidative stress may constitute a major pathogenic factor in the development of hypertension and type 2 diabetes. Moreover, our studies suggest that the chronic treatment with appropriate antioxidative therapies could prevent the development of hypertension and diabetes as well as their complications in various experimental models of hypertension.  相似文献   
999.
The effect of the Ca2Mg6Zn3 phase on the corrosion behavior of biodegradable Mg-4.0Zn-0.2Mn-xCa (ZM-xCa, x = 0.1, 0.3, 0.5 and 1.0 wt.%) alloys in Hank’s solution was investigated with respect to phase spacing, morphology, distribution and volume fraction. With the increase in Ca addition, the volume fraction of the Ca2Mg6Zn3 phase increased from 2.5% to 7.6%, while its spacing declined monotonically from 43 μm to 30 μm. The Volta potentials of secondary phases relative to the Mg matrix were measured by using scanning kelvin probe force microscopy (SKPFM). The results show that the Volta potential of the intragranular spherical Ca2Mg6Zn3 phase (+109 mV) was higher than that of the dendritic Ca2Mg6Zn3 phase (+80 mV). It is suggested that the Ca2Mg6Zn3 acted as a cathode to accelerate the corrosion process due to the micro-galvanic effect. The corrosion preferred to occur around the spherical Ca2Mg6Zn3 phase at the early stage and developed into the intragranular region. The corrosion rate increased slightly with increasing Ca content from 0.1 wt.% to 0.5 wt.% because of the enhanced micro-galvanic corrosion effect. The decrease in the phase spacing and sharp increase in the secondary phase content resulted in a dramatic increase in the corrosion rate of the ZM-1.0Ca alloy.  相似文献   
1000.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号