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   2016篇
  免费   96篇
  国内免费   6篇
耳鼻咽喉   47篇
儿科学   92篇
妇产科学   86篇
基础医学   127篇
口腔科学   183篇
临床医学   116篇
内科学   417篇
皮肤病学   45篇
神经病学   69篇
特种医学   44篇
外国民族医学   1篇
外科学   325篇
综合类   59篇
预防医学   96篇
眼科学   63篇
药学   216篇
中国医学   14篇
肿瘤学   118篇
  2023年   12篇
  2022年   38篇
  2021年   96篇
  2020年   53篇
  2019年   86篇
  2018年   80篇
  2017年   68篇
  2016年   50篇
  2015年   57篇
  2014年   67篇
  2013年   99篇
  2012年   151篇
  2011年   159篇
  2010年   74篇
  2009年   79篇
  2008年   103篇
  2007年   97篇
  2006年   80篇
  2005年   63篇
  2004年   45篇
  2003年   45篇
  2002年   36篇
  2001年   43篇
  2000年   32篇
  1999年   28篇
  1998年   15篇
  1997年   10篇
  1996年   20篇
  1995年   14篇
  1994年   8篇
  1992年   11篇
  1991年   21篇
  1990年   11篇
  1989年   20篇
  1988年   31篇
  1987年   25篇
  1986年   18篇
  1985年   20篇
  1984年   11篇
  1983年   8篇
  1982年   6篇
  1979年   14篇
  1978年   10篇
  1977年   11篇
  1976年   17篇
  1975年   7篇
  1974年   12篇
  1973年   6篇
  1972年   10篇
  1966年   7篇
排序方式: 共有2118条查询结果,搜索用时 15 毫秒
81.
82.
Vitamin D is critical for calcium, phosphate homeostasis and for mineralization of the skeleton, especially during periods of rapid growth. Vitamin D Deficiency leads to rickets (in children) and osteomalacia (in adults). Expression and activation of the vitamin D receptor (VDR) are necessary for the effects of vitamin D, in which several single nucleotide polymorphisms have been identified especially (FokI, BsmI). In this study serum 25 (OH) vitamin D3 levels were estimated by Enzyme Linked Immunosorbent Assay [ELISA], VDR (FokI, BsmI) gene polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism assay [PCR–RFLP].Serum levels of calcium, phosphorus, alkaline phosphatase and ferritin were determined in 50 Pediatrics beta thalassemia major patients and 60 controls. Patients had significantly lower serum calcium (p < 0.001) lower serum vitamin D3 (p < 0.001) with elevated levels of phosphorus (p < 0.001) and alkaline phosphatase than controls (p = 0.04). Of the patients studied, 60 % had vitamin D deficiency (<20 ng/ml), 20 % had vitamin D insufficiency (21–30 ng/ml) and 20 % had sufficient vitamin D status (>30 ng/ml). Patients harboring mutant (Ff,ff) and wild (BB) genotypes were associated with lower serum calcium (p = 0.08, 0.02) respectively, lower vitamin D3 levels (p < 0.001, 0.01) respectively. They were also suffering from more bony complications although the difference was not statistically significant (p > 0.05). In conclusion, these results suggest that the VDR (FokI, BsmI) gene polymorphisms influence vitamin D status, (Ff,ff), BB genotypes had lower vitamin D levels, so they might influence risk of development of bone diseases in beta thalassemia major.  相似文献   
83.

Background

Data are limited about race-and sex-associated differences in prognostically important ECG measures of regional repolarization.

Methods and results

The normal reference group from the Atherosclerosis Risk in Communities (ARIC) study included 8,676 white and African-American men and women aged 40–65 years. Exclusion criteria included cardiovascular disease, hypertension, diabetes and major ECG abnormalities. Notable sex differences (p < 0.001) were observed in the upper 98% limits for rate-adjusted QTend (QTea) which was 435 ms in white and African-American men and 445 ms in white and African-American women, and for left ventricular epicardial repolarization time (RTepi) which was 345 ms in white and African-American men and 465 ms in white and African-American women. These sex differences reflect earlier onset and end of repolarization in men than in women. Upper normal limits for STJ amplitude in V2–V3 were 100 μV in white and African-American women, 150 μV in white men and 200 μV in African-American men (p < 0.001 for sex differences), and for other chest leads, aVL and aVF 50 μV in white women, 100 μV in African-American women, 100 μV in white men and 150 μV in African-American men (p < 0.001 for sex and race differences).

Conclusions

Shorter QTea and RTepi in men than in women reflect earlier onset and end of repolarization in men. STJ amplitudes in African-American men were higher than in other subgroups by race and sex. These sex and race differences need to be considered in clinical and epidemiological applications of normal standards.  相似文献   
84.
85.

INTRODUCTION

Double dislocations of carpometacarpal and metacarpo-phanlageal joints are rare. We report an unusual case of simultaneous dislocation of both CMC and MCP joints in the thumb.

PRESENTATION OF CASE

A 31 year old male was admitted following a road traffic accident. He was complaining of pain and deformity of right thumb. The X-ray examination revealed simultaneous dislocation of both CMC and MCP joints. He underwent closed manipulative reduction and percutaneous K wire fixation. The wires were removed after six weeks. After a course of physiotherapy he regained full range of pain free movements.

DISCUSSION

The incidence of simultaneous dislocation of both CMC and MCP joints in thumb are associated with high energy injuries. The options of treatment are conservative with cast immobilisation and serial X-rays or operative including closed manipulative reduction and K wire fixation or open reduction and internal fixation.

CONCLUSION

The option of treating this rare injury with closed manipulative reduction and percutaneous K wiring gives excellent and predictable results.  相似文献   
86.
87.
The current study investigated the macroscopic and microscopic differences between pennaceous and plumulaceous feathers. The morphology of the barbules distinguished pennaceous and plumulaceous feathers, particularly the shape of barbules during their development. In pennaceous feathers, the initial barbules were large and elongated or pyriform in shape, while plumulaceous feathers had small, thin, elongated initial barbules. The spinous barbules were characteristic of pennaceous feathers. The histochemical reactivity of both feather types for Mallory trichrome, orange G, and acridine orange, safranin O, PAS, and methylene blue was determined. Keratin was detected by Mallory trichrome, orange G, and acridine orange. In conclusion, the histochemical properties of pennaceous and plumulaceous feathers of quail, particularly the distribution and nature of keratin during development, should be considered in future studies. The unique morphological features of pennaceous and plumulaceous feathers could be used as a guide for phylogenetic identification. Anat Rec, 2019. © 2019 American Association for Anatomy Anat Rec, 303:1865–1883, 2020. © 2019 American Association for Anatomy  相似文献   
88.

Background

There is a great need for novel strategies to overcome the high mortality associated with invasive pulmonary aspergillosis (IPA) in immunocompromised patients. To evaluate the antifungal and antihepatotoxic potentials of Sepia ink extract, its effect on liver oxidative stress levels was analyzed against IPA in neutropenic mice using amphotercin B as a reference drug.

Materials and Methods

Eighty neutropenic infected mice were randomly assigned into four main groups. The 1st group was treated with saline, neutropenic infected (NI), the 2nd group was treated with ink extract (200 mg/kg) (IE) and the 3rd group was treated with amphotericin B (150 mg/kg) (AMB) and 4th group was treated with IE plus AMB. Treatment was started at 24 h after fungal inoculation (1×109 conidia/ml).

Results

The present study revealed good in vitro and in vivo antifungal activity of IE against A. fumigatus. IE significantly reduced hepatic fungal burden and returns liver function and histology to normal levels. Compared with the untreated infected group, mice in the IE, AMB, and IE+ AMB groups had increased glutathione reduced (GSH) and superoxide dismutase (SOD) and significantly reduced malondialdehyde (MDA) levels at 24 and 72 h after inoculation with A. fumigatus conidia.

Conclusion

It is then concluded that in combination with antifungal therapy (AMB), IE treatment can reduce hepatic fungal burden, alleviate hepatic granulomatous lesions and oxidative stress associated with IPA in neutropenic mice  相似文献   
89.
90.
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