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   35941篇
  免费   3326篇
  国内免费   2598篇
耳鼻咽喉   409篇
儿科学   404篇
妇产科学   381篇
基础医学   4180篇
口腔科学   598篇
临床医学   4904篇
内科学   5088篇
皮肤病学   375篇
神经病学   2013篇
特种医学   1344篇
外国民族医学   26篇
外科学   3332篇
综合类   6908篇
现状与发展   12篇
预防医学   2194篇
眼科学   1107篇
药学   3743篇
  32篇
中国医学   2016篇
肿瘤学   2799篇
  2024年   112篇
  2023年   641篇
  2022年   1439篇
  2021年   1936篇
  2020年   1496篇
  2019年   1260篇
  2018年   1298篇
  2017年   1250篇
  2016年   1071篇
  2015年   1653篇
  2014年   2082篇
  2013年   1790篇
  2012年   2753篇
  2011年   2863篇
  2010年   1720篇
  2009年   1366篇
  2008年   1649篇
  2007年   1740篇
  2006年   1745篇
  2005年   1766篇
  2004年   1113篇
  2003年   1073篇
  2002年   929篇
  2001年   853篇
  2000年   866篇
  1999年   994篇
  1998年   620篇
  1997年   686篇
  1996年   514篇
  1995年   436篇
  1994年   367篇
  1993年   221篇
  1992年   288篇
  1991年   250篇
  1990年   214篇
  1989年   188篇
  1988年   176篇
  1987年   132篇
  1986年   102篇
  1985年   77篇
  1984年   38篇
  1983年   21篇
  1982年   29篇
  1981年   15篇
  1980年   10篇
  1979年   10篇
  1965年   2篇
  1940年   3篇
  1935年   2篇
  1934年   1篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
991.
Treatment for optic nerve injury by brain-derived neurotrophic factor or the transplantation of human umbilical cord blood stem cells has gained progress, but analysis by biomechanical indicators is rare. Rabbit models of optic nerve injury were established by a clamp. At 7 days after injury, the vitreous body received a one-time injection of 50 μg brain-derived neurotrophic factor or 1 × 106 human umbilical cord blood stem cells. After 30 days, the maximum load, maximum stress, maximum strain, elastic limit load, elastic limit stress, and elastic limit strain had clearly improved in rabbit models of optical nerve injury after treatment with brain-derived neurotrophic factor or human umbilical cord blood stem cells. The damage to the ultrastructure of the optic nerve had also been reduced. These findings suggest that human umbilical cord blood stem cells and brain-derived neurotrophic factor effectively repair the injured optical nerve, improve biomechanical properties, and contribute to the recovery after injury.  相似文献   
992.
This study investigated the attention modulation of disgust in comparison with anger in a dot-probe task. Results indicated a two-stage processing of attention modulation by threats. When participants viewed the cues that were represented by Chinese faces (i.e. the in-group condition), it was found at the early processing stage that an angry face elicited a larger occipital P1 component whereas a disgusted face elicited a smaller P1 for validly than for invalidly cued targets. However, the result pattern was reversed at the later processing stage: the P3 amplitudes were larger for valid disgust cues but were smaller for valid angry cues, when both were compared with invalid cue conditions. In addition, when participants viewed the cues that were represented by foreign faces (i.e. the out-group condition), the attention modulation of disgust/anger diminished at the early stage, whereas enhanced P3 amplitudes were observed in response to validly cued targets in both disgusting and angry conditions at the later stage. The current result implied that although people can perceptually differentiate the emotional categories of out-group faces as accurately as in-group faces, they may still be not able to psychologically understand the subtle differences behind different categories of out-group facial expressions.  相似文献   
993.
994.

Background

Previous functional MRI (fMRI) studies have demonstrated group differences in brain activity between deceptive and honest responses. The functional connectivity network related to lie-telling remains largely uncharacterized.

Methods

In this study, we designed a lie-telling experiment that emphasized strategy devising. Thirty-two subjects underwent fMRI while responding to questions in a truthful, inverse, or deceitful manner. For each subject, whole-brain functional connectivity networks were constructed from correlations among brain regions for the lie-telling and truth-telling conditions. Then, a multivariate pattern analysis approach was used to distinguish lie-telling from truth-telling based on the functional connectivity networks.

Results

The classification results demonstrated that lie-telling could be differentiated from truth-telling with an accuracy of 82.81% (85.94% for lie-telling, 79.69% for truth-telling). The connectivities related to the fronto-parietal networks, cerebellum and cingulo-opercular networks are most discriminating, implying crucial roles for these three networks in the processing of deception.

Conclusions

The current study may shed new light on the neural pattern of deception from a functional integration viewpoint.

Electronic supplementary material

The online version of this article (doi:10.1186/s12993-014-0046-4) contains supplementary material, which is available to authorized users.  相似文献   
995.
996.
目的了解结核病专科医院护士的营养知识和态度的现状,分析其相关性,为针对性地进行营养知识培训提供依据。方法采用方便抽样的方法,对某三甲结核病专科医院的256名临床护士的营养知识和态度进行调查。结果护士营养知识正确率53.74%,得分(16.12±4.56)分,其中良好、一般、差者分别占1.2%、41.0%、57.8%;不同年龄、工作年限、学历、职务、编制、工作状况护士的营养知识掌握情况比较,差异有统计学意义(P0.05,P0.01);态度得分为(94.56±10.53)分,持正性、中性、负性态度者分别占64.5%、33.6%、1.9%,不同职称护士的营养态度得分差异有统计学意义(P0.01);营养知识与态度呈正相关(P0.01)。结论护理管理者应加强对护士营养知识的培训,端正其对营养的态度,从而提高营养护理质量。  相似文献   
997.
998.
We assessed the relation between different fasting plasma glucose (FPG) levels of 5.6 to 6.9 mmol/L and the prevalence and severity of angiographic coronary artery disease (CAD) in high-risk Chinese patients. Among 512 subjects who were to undergo coronary angiography for the confirmation of suspected myocardial ischemia, 409 subjects were enrolled and categorized into 3 groups based on FPG levels: (1) 相似文献   
999.
AIM: To investigate the effects of Danshao Huaxian (DSHX) capsules, a preparation of traditional Chinese medicine, on the expression of matrix metalloproteinase-1 (MMP-1), and tissue inhibitor of metalloproteinase-1 (TIMP-1) in the fibrous livers of rats. METHODS: Eighty male Wistar rats were randomly divided into normal control group (group A), CCl4-induced hepatic fibrosis group (group B), non-DSHX-treated group (group C), low dose-treated group (group D), and high dose-treated group (group E). Fibrous liver models in rats were induced by subcutaneous injection of CCl4, oral administration of alcohol and high-lipid/low-protein diet for 8 wk. After the models were established, the rats in groups D and E were orally given a low dose (0.5 g/kg) and a high dose (1.0 g/kg) of DSHX daily for 8 wk, respectively. Then, the liver indexes, serum hyaluronic acid (HA) and alanine aminotransferase (ALT) were examined. The degree of hepatic fibrosis was evaluated by optical microscopy. Hydroxyproline (Hyp) in the urine was determined, and the expression of MMP-1 and TIMP-1 was detected by immunohistochemical techniques. RESULTS: In groups D and E, the liver indexes, levels of serum HA and ALT reduced and development of hepatic fibrosis weakened significantly. The urinary Hyp and expression of MMP-1 in the liver tissues elevated, but the expression of TIMP-1 decreased obviously, as compared to groups B and C. CONCLUSION: DSHX enhances the expression of MMP-1 but decreases that of TIMP-1 in liver tissues of CCl4-induced hepatic fibrotic rats, which may result in its elevated activity that contributes to fighting against hepatic fibrosis.  相似文献   
1000.
To investigate differences in growth hormone (GH) and estrogen activation of insulin-like growth factor-I (IGF-I) expression, we have examined the effects of cycloheximide on hepatic and uterine IGF-I mRNA abundance in response to GH and 17 beta-estradiol (E2) respectively. In hypophysectomized (hypox) rats a single injection of GH significantly increased hepatic IGF-I mRNA 3.65 +/- 0.68-fold, P less than 0.005, 6 h after injection. Administration of cycloheximide 30 min prior to GH injection completely abolished this response. In contrast, in pituitary intact rats killed 6 h after administration of cycloheximide, hepatic IGF-I mRNA abundance was not significantly different from untreated control rats although the serum IGF-I concentration was significantly reduced; 119.9 +/- 11.8 vs. 270.2 +/- 48.7 ng/ml, P less than 0.005. In immature rats, injection of E2 (1 micrograms/100 g body weight) significantly increased uterine IGF-I mRNA 4.1 +/- 0.4-fold. Cycloheximide did not block the E2-induced increase in IGF-I mRNA but rather significantly enhanced the IGF-I response. These data indicate that continuing protein synthesis is required for GH induction of hepatic IGF-I mRNA in the hypox rat but is not required for E2 induction of uterine IGF-I mRNA. Furthermore, in pituitary-intact rats protein synthesis is not required for maintenance of hepatic IGF-I mRNA levels.  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