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   4291篇
  免费   263篇
  国内免费   23篇
耳鼻咽喉   43篇
儿科学   153篇
妇产科学   121篇
基础医学   533篇
口腔科学   106篇
临床医学   395篇
内科学   933篇
皮肤病学   68篇
神经病学   417篇
特种医学   203篇
外科学   491篇
综合类   22篇
一般理论   1篇
预防医学   362篇
眼科学   62篇
药学   297篇
中国医学   10篇
肿瘤学   360篇
  2024年   6篇
  2023年   35篇
  2022年   74篇
  2021年   140篇
  2020年   109篇
  2019年   127篇
  2018年   122篇
  2017年   94篇
  2016年   126篇
  2015年   128篇
  2014年   181篇
  2013年   233篇
  2012年   372篇
  2011年   404篇
  2010年   182篇
  2009年   158篇
  2008年   298篇
  2007年   316篇
  2006年   277篇
  2005年   281篇
  2004年   247篇
  2003年   209篇
  2002年   166篇
  2001年   37篇
  2000年   33篇
  1999年   29篇
  1998年   27篇
  1997年   24篇
  1996年   8篇
  1995年   13篇
  1994年   20篇
  1993年   10篇
  1992年   9篇
  1991年   7篇
  1990年   4篇
  1989年   6篇
  1988年   3篇
  1985年   5篇
  1984年   3篇
  1983年   3篇
  1982年   6篇
  1981年   3篇
  1979年   3篇
  1978年   4篇
  1977年   4篇
  1976年   3篇
  1972年   2篇
  1971年   4篇
  1969年   7篇
  1968年   4篇
排序方式: 共有4577条查询结果,搜索用时 15 毫秒
71.
Increasing evidence has indicated that activated glial cells releasing nociceptive factors, such as interleukins and chemokines, are of key importance for neuropathic pain. Significant changes in the production of nociceptive factors are associated with the low effectiveness of opioids in neuropathic pain. Recently, it has been suggested that CCL2/CCR2 signaling is important for nociception. Here, we studied the time course changes in the mRNA/protein level of CD40/Iba-1, CCL2 and CCR2 in the spinal cord/dorsal root ganglia (DRG) in rats following chronic constriction injury (CCI) of the sciatic nerve. Moreover, we examined the influence of intrathecal preemptive and repeated (daily for 7 days) administration of RS504393, CCR2 antagonist, on pain-related behavior and the associated biochemical changes of some nociceptive factors as well as its influence on opioid effectiveness. We observed simultaneous upregulation of Iba-1, CCL2, CCR2 in the spinal cord on 7th day after CCI. Additionally, we demonstrated that repeated administration of RS504393 not only attenuated tactile/thermal hypersensitivity but also enhanced the analgesic properties of morphine and buprenorphine under neuropathy. Our results proof that repeated administration of RS504393 reduced the mRNA and/or protein levels of pronociceptive factors, such as IL-1beta, IL-18, IL-6 and inducible nitric oxide synthase (iNOS), and some of their receptors in the spinal cord and/or DRG. Furthermore, RS504393 elevated the spinal protein level of antinociceptive IL-1alpha and IL-18 binding protein. Our data provide new evidence that CCR2 is a promising target for diminishing neuropathic pain and enhancing the opioid analgesic effects.  相似文献   
72.
Spinocerebellar ataxia type 31 (SCA31) is an autosomal dominant form of pure cerebellar ataxia that is caused by a disease‐specific insertion containing penta‐nucleotide repeats (TGGAA)n. Neuropathologically, cerebellar Purkinje cells are preferentially affected and reduced in number in SCA31, and they are often surrounded by halo‐like amorphous materials. In the present study, we performed neuropathological analyses on two SCA31 brains, and discussed the serial morphological changes of Purkinje cells in SCA31.We found that bent, elongated, often folded nuclei were observed frequently in degenerating Purkinje cells with the halo‐like structure. Conversely, Purkinje cells without this structure developed marked atrophy with severely slender and condensed nuclei. On the basis of these pathological findings, we propose two different processes for Purkinje cell degeneration in SCA31, namely, shrinkage of Purkinje cells with or without the halo‐like amorphous materials. The former, but not the latter, was considered to be specific to SCA31. Correspondingly, fragmentation of the Golgi apparatus was observed more frequently in Purkinje cells with the halo‐like structure than in those without this structure. We consider that the profound nuclear deformity and fragmentation of the Golgi apparatus are closely linked with the formation of the halo‐like structure in SCA31.  相似文献   
73.
74.
Although more widespread screening and routine adjuvant therapy has improved the outcome for breast cancer patients in recent years, there remains considerable scope for improving the efficacy, safety and tolerability of adjuvant therapy in the early stage disease and the treatment of advanced disease. Toremifene is a selective estrogen receptor modifier (SERM) that has been widely used for decades in hormone receptor positive breast cancer both in early and late stage disease. Its efficacy has been well established in nine prospective randomized phase III trials compared to tamoxifen involving more than 5500 patients, as well as in several large uncontrolled and non-randomized studies. Although most studies show therapeutic equivalence between the two SERMs, some show an advantage for toremifene. Several meta-analyses have also confirmed that the efficacy of toremifene is at least as good as that of tamoxifen. In terms of safety and tolerability toremifene is broadly similar to tamoxifen although there is some evidence that toremifene is less likely to cause uterine neoplasms, serious vascular events and it has a more positive effect on serum lipids than does tamoxifen. Toremifene is therefore effective and safe in the treatment of breast cancer. It provides not only a useful therapeutic alternative to tamoxifen, but may bring specific benefits.  相似文献   
75.
76.
77.
78.
The measurement of water diffusion by diffusion‐weighted MRI (DWI) in vivo offers a non‐invasive method for assessing tissue responses to anti‐cancer therapies. The pathway of cell death after anti‐cancer treatment is often apoptosis, which leads to accumulation of mobile lipids detectable by 1H MRS in vivo. However, it is not known how these discrete MR markers of cell death relate to each other. In a rodent tumour model [i.e. ganciclovir‐treated herpes simplex thymidine kinase (HSV‐tk) gene‐transfected BT4C gliomas], we studied the interrelationships between water diffusion (Trace{D}) and mobile lipids during apoptosis. Water diffusion and water‐referenced concentrations of mobile lipids showed clearly increasing and interconnected trends during treatment. Of the accumulating 1H MRS‐visible lipids, the fatty acid ? CH ?CH ? groups and cholesterol compounds showed the strongest associations with water diffusion (r2 = 0.30; P < 0.05 and r2 = 0.48; P < 0.01, respectively). These results indicate that the tumour histopathology and apoptotic processes during tumour shrinkage can be interrelated in vivo by DWI of tissue water and 1H MRS of mobile lipids, respectively. However, there is considerable individual variation in the associations, particularly at the end of the treatment period, and in the relative compositions of the accumulating NMR‐visible lipids. The findings suggest that the assessment of individual treatment response in vivo may benefit from combining DWI and 1H MRS. Absolute and relative changes in mobile lipids may indicate initiation of tumour shrinkage even when changes in tissue water diffusion are still small. Conversely, greatly increased water diffusion probably indicates that substantial cell decomposition has taken place in the tumour tissue when the 1H MRS resonances of mobile lipids alone can no longer give a reliable estimate of tissue conditions. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
79.
We describe the case of a 72-year-old asymptomatic man with a cholangiocarcinoma arising from a biliary hamartoma, also referred to as "von Meyenburg's complex". The patient was clinically diagnosed as having a cystadenocarcinoma, but the tumor had already been present as a uniformly low-density area on computed tomography taken four years previously, as revealed by retrospective examination of the computed tomography films that had been taken annually after surgery for pulmonary emphysema. The low-density area had continued to enlarge year after year, and a high-density area was observed to have emerged inside the low-density area on computed tomography. Histopathological examination demonstrated that the high-density area corresponded to the cholangiocarcinoma and the low-density area to a biliary hamartoma. This is the first case in which it was possible to confirm the presence of cholangiocarcinoma inside a biliary hamartoma that had continued to increase in size.  相似文献   
80.

BACKGROUND

Diet quality is associated with brain aging outcomes. However, few studies have explored in humans the brain structures potentially affected by long-term diet quality. We examined whether cumulative average of the Alternative Healthy Eating Index 2010 (AHEI-2010) score during adult life (an 11-year exposure period) is associated with hippocampal volume.

METHODS

Analyses were based on data from 459 participants of the Whitehall II imaging sub-study (mean age [standard deviation] (SD)?=?59.6 [5.3] years in 2002-2004, 19.2% women). Multimodal magnetic resonance imaging examination was performed at the end of follow-up (2015-2016). Structural images were acquired using a high-resolution 3-dimensional T1-weighted sequence and processed with Functional Magnetic Resonance Imaging of the Brain Software Library (FSL) tools. An automated model-based segmentation and registration tool was applied to extract hippocampal volumes.

RESULTS

Higher AHEI-2010 cumulative average score (reflecting long-term healthy diet quality) was associated with a larger total hippocampal volume. For each 1 SD (SD?=?8.7 points) increment in AHEI-2010 score, an increase of 92.5 mm3 (standard error?=?42.0 mm3) in total hippocampal volume was observed. This association was independent of sociodemographic factors, smoking habits, physical activity, cardiometabolic health factors, cognitive impairment, and depressive symptoms, and was more pronounced in the left hippocampus than in the right hippocampus. Of the AHEI-2010 components, no or light alcohol consumption was independently associated with larger hippocampal volume.

CONCLUSIONS

Higher long-term AHEI-2010 scores were associated with larger hippocampal volume. Accounting for the importance of hippocampal structures in several neuropsychiatric diseases, our findings reaffirm the need to consider adherence to healthy dietary recommendation in multi-interventional programs to promote healthy brain aging.  相似文献   
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