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   76285篇
  免费   4185篇
  国内免费   361篇
耳鼻咽喉   1470篇
儿科学   2443篇
妇产科学   1723篇
基础医学   10055篇
口腔科学   2525篇
临床医学   5369篇
内科学   18814篇
皮肤病学   2468篇
神经病学   6418篇
特种医学   1646篇
外国民族医学   1篇
外科学   9003篇
综合类   490篇
一般理论   22篇
预防医学   7442篇
眼科学   1356篇
药学   5427篇
中国医学   479篇
肿瘤学   3680篇
  2023年   520篇
  2022年   1225篇
  2021年   2965篇
  2020年   1396篇
  2019年   2503篇
  2018年   2970篇
  2017年   1794篇
  2016年   1756篇
  2015年   1999篇
  2014年   2926篇
  2013年   3971篇
  2012年   5658篇
  2011年   6011篇
  2010年   3347篇
  2009年   2831篇
  2008年   4309篇
  2007年   4484篇
  2006年   4126篇
  2005年   4157篇
  2004年   3727篇
  2003年   3444篇
  2002年   3076篇
  2001年   1641篇
  2000年   1768篇
  1999年   1465篇
  1998年   494篇
  1997年   437篇
  1996年   334篇
  1995年   302篇
  1994年   256篇
  1993年   194篇
  1992年   541篇
  1991年   443篇
  1990年   424篇
  1989年   321篇
  1988年   321篇
  1987年   284篇
  1986年   252篇
  1985年   241篇
  1984年   153篇
  1983年   153篇
  1982年   116篇
  1981年   125篇
  1980年   99篇
  1979年   144篇
  1978年   111篇
  1974年   107篇
  1971年   89篇
  1969年   89篇
  1968年   75篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
This study investigated the effect of resveratrol on bone healing and its influence on the gene expression of bone-related markers in rats exposed to cigarette smoke. Two calvarial defects were created in each of 60 rats, which were assigned equally (n = 20) to three groups: (1) resveratrol (10 mg/kg) + smoke exposure (SMK + RESV); (2) placebo + smoke exposure (SMK + PLA); or (3) placebo + no smoke exposure (NS + PLA). Substances were administered daily for 30 days following surgery. Smoke inhalation was started 7 days before surgery and continued for 30 days after surgery. One defect was processed for histomorphometric analysis and the other was used for mRNA quantification of bone-related gene expression by qPCR. The remaining defect was smaller in the SMK + RESV (2.27 ± 0.61 mm, P = 0.0003) and NS + PLA (2.17 ± 0.74 mm, P = 0.0005) groups than in the SMK + PLA group (3.12 ± 0.47 mm). Higher levels of Runx2 were observed in the NS + PLA group than in the smoke exposure groups (vs. SMK + PLA, P = 0002; vs. SMK + RESV, P = 0.052); levels of Lrp-5 were also higher in the no smoke exposure group (vs. SMK + RESV, P = 0.009; vs. SMK + PLA, P = 0.003). Resveratrol therapy decreased RANKL/OPG expression when compared to placebo (SMK + RESV vs. SMK + PLA, P = 0.017). Dkk1 levels were decreased in the SMK + RESV group when compared to the SMK + PLA (P = 0.006) and NS + PLA groups (P = 0.005). In conclusion, resveratrol optimizes the repair of critical-sized bone defects, up-regulating the gene expression of important bone remodelling markers in rats exposed to cigarette smoke inhalation.  相似文献   
993.
Third-degree burn wounds are considered severe injuries because they destroy all the skin layers and may affect subcutaneous tissues, fasciae, muscles, and bones. To favor the healing process of the injured tissues, it is very useful to diminish the occurrence of the inflammatory process. The present study was aimed at comparing the effect of different energetic densities of AlGaInP laser on the inflammatory process and in the healing of third-degree burn wounds in Wistar rats. This study was approved by the Ethics Committee, in which 36 adult male rats were selected and suffered the induction of third-degree burn injury. These rats were divided as follows: group 1—control (treated with silver sulfadiazine), group 2—received energy density of 3 J/cm2, and group 3—received energy density of 6 J/cm2. All animals daily received an occlusive bandage with silver sulfadiazine and 8 % papain. The laser therapy was performed alternatively three times a week. The animals were evaluated on the 3rd, 7th, 14th, and 21st days after the initial lesion and euthanized for the macroscopic, histologic, and morphometric analysis. A higher production of collagen was observed at 7 days and a greater re-epithelialization at 21 days in group 3 (6 J/cm2). Furthermore, the latter when compared to the other groups presented macroscopically a better aspect of the scar at 21 days with more granulation tissue and fibrosis. We conclude that the AlGaInP laser used in dosages of 3 and 6 J/cm2 favors the healing of third-degree burn wounds induced in rats.  相似文献   
994.
IntroductionAlpha-1 antitrypsin deficiency (AATD) is a genetic condition resulting in lung and liver disease with a great clinical variability. MicroRNAs have been identified as disease modifiers; therefore miRNA deregulation could play an important role in disease heterogeneity. Members of miR-320 family are involved in regulating of multiple processes including inflammation, and have potential specific binding sites in the 3′UTR region of SERPINA1 gene. In this study we explore the involvement of miR-320c, a member of this family, in this disease.MethodsFirstly in vitro studies were carried out to demonstrate regulation of SERPINA1 gene by miR-320. Furthermore, the expression of miR-320c was analyzed in the blood of 98 individuals with different AAT serum levels by using quantitative PCR and expression was correlated to clinical parameters of the patients. Finally, HL60 cells were used to analyze induction of miR-320c in inflammatory conditions.ResultsOverexpression of miR-320 members in human HepG2 cells led to inhibition of SERPINA1 expression. Analysis of miR-320c expression in patient's samples revealed significantly increased expression of miR-320c in individuals with pulmonary disease. Additionally, HL60 cells treated with the pro-inflammatory factor lipopolysaccharide (LPS) showed increase in miR-320c expression, suggesting that miR-320c responds to inflammation.ConclusionOur findings demonstrate that miR-320c inhibits SERPINA1 expression in a hepatic cell line and its levels in blood are associated with lung disease in a cohort of patients with different AAT serum levels. These results suggest that miR-320c can play a role in AAT regulation and could be a biomarker of inflammatory processes in pulmonary diseases.  相似文献   
995.
996.
997.
998.
This study aimed to identify vulnerability patterns in psychological, physiological and neural responses to mild psychosocial challenge in a population that is at a direct risk of developing depression, but who has not as yet succumbed to the full clinical syndrome. A group of healthy and a group of subclinically depressed participants underwent a modified Montreal Imaging Stress task (MIST), a mild neuroimaging psychosocial task and completed state self-esteem and mood measures. Cortisol levels were assessed throughout the session. All participants showed a decrease in performance self-esteem levels following the MIST. Yet, the decline in performance self-esteem levels was associated with increased levels of anxiety and confusion in the healthy group, but increased levels of depression in the subclinical group, following the MIST. The subclinical group showed overall lower cortisol levels compared with the healthy group. The degree of change in activity in the subgenual anterior cingulate cortex in response to negative evaluation was associated with increased levels of depression in the whole sample. Findings suggest that even in response to a mild psychosocial challenge, those individuals vulnerable to depression already show important maladaptive response patterns at psychological and neural levels. The findings point to important targets for future interventions.  相似文献   
999.
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