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   6750篇
  免费   764篇
  国内免费   579篇
耳鼻咽喉   180篇
儿科学   63篇
妇产科学   66篇
基础医学   840篇
口腔科学   89篇
临床医学   934篇
内科学   948篇
皮肤病学   86篇
神经病学   353篇
特种医学   319篇
外国民族医学   2篇
外科学   706篇
综合类   1235篇
现状与发展   2篇
预防医学   403篇
眼科学   120篇
药学   738篇
  12篇
中国医学   433篇
肿瘤学   564篇
  2024年   9篇
  2023年   112篇
  2022年   187篇
  2021年   333篇
  2020年   280篇
  2019年   251篇
  2018年   247篇
  2017年   258篇
  2016年   234篇
  2015年   395篇
  2014年   434篇
  2013年   355篇
  2012年   491篇
  2011年   633篇
  2010年   412篇
  2009年   290篇
  2008年   398篇
  2007年   332篇
  2006年   389篇
  2005年   366篇
  2004年   220篇
  2003年   262篇
  2002年   205篇
  2001年   186篇
  2000年   161篇
  1999年   119篇
  1998年   77篇
  1997年   79篇
  1996年   56篇
  1995年   63篇
  1994年   41篇
  1993年   21篇
  1992年   32篇
  1991年   29篇
  1990年   26篇
  1989年   24篇
  1988年   23篇
  1987年   13篇
  1986年   13篇
  1985年   18篇
  1984年   4篇
  1983年   5篇
  1982年   3篇
  1981年   4篇
  1979年   1篇
  1976年   1篇
  1932年   1篇
排序方式: 共有8093条查询结果,搜索用时 31 毫秒
91.

Background:

Inflammation plays a pivotal role in the formation and progression of ischemic stroke. Recently, more and more epidemiological studies have focused on the association between C-reactive protein (CRP) −717A > G and −286C > T > A genetic polymorphisms and ischemic stroke. However, the findings of these researches are not conclusive.

Methods:

We performed a meta-analysis to determine whether these two polymorphisms are associated with the risk of ischemic stroke. Eligible studies were identified from the database of PubMed, Medline, Embase, Web of Science, CNKI, Weipu, and Wanfang. We calculated odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association.

Results:

Four articles were included in our study, including 1926 cases and 2678 controls for −717A > G polymorphism, 652 cases and 1103 controls for −286C > T > A polymorphism. The results of meta-analysis showed that single nucleotide polymorphism (SNP) −717A > G was not significantly associated with the risk of ischemic stroke (GG vs. AA, OR = 1.12, 95% CI = 0.83–1.50, P = 0.207; GG + GA vs. AA, OR = 1.04, 95% CI = 0.93–1.17, P = 0.533; GG vs. GA + AA, OR = 1.10, 95% CI = 0.82–1.47, P = 0.220). Meta-analysis of SNP − 286C > T > A also demonstrated no statistical evidence of a significant association with the risk of ischemic stroke (AA vs. CC, OR = 0.86, 95% CI = 0.59–1.25, P = 0.348; AA vs. CC, OR = 0.92, 95% CI = 0.80–1.06, P = 0.609; AA vs. CC, OR = 0.89, 95% CI = 0.62–1.30, P = 0.374).

Conclusions:

This meta-analysis demonstrated little evidence to support a role of CRP gene −717A > G, −286C > T > A polymorphisms in ischemic stroke predisposition. However, to draw comprehensive and more reliable conclusions, further larger studies are needed to validate the association between CRP gene polymorphisms and ischemic stroke in various ethnic groups.  相似文献   
92.

Background:

Current randomized trials have demonstrated the effects of short-term rosuvastatin therapy in preventing contrast-induced acute kidney injury (CIAKI). However, the consistency of these effects on patients administered different volumes of contrast media is unknown.

Methods:

In the TRACK-D trial, 2998 patients with type 2 diabetes and concomitant chronic kidney disease (CKD) who underwent coronary/peripheral arterial angiography with or without percutaneous intervention were randomized to short-term (2 days before and 3 days after procedure) rosuvastatin therapy or standard-of-care. This prespecified analysis compared the effects of rosuvastatin versus standard therapy in patients exposed to (moderate contrast volume [MCV], 200–300 ml, n = 712) or (high contrast volume [HCV], ≥300 ml, n = 220). The primary outcome was the incidence of CIAKI. The secondary outcome was a composite of death, dialysis/hemofiltration or worsened heart failure at 30 days.

Results:

Rosuvastatin treatment was associated with a significant reduction in CIAKI compared with the controls (2.1% vs. 4.4%, P = 0.050) in the overall cohort and in patients with MCV (1.7% vs. 4.5%, P = 0.029), whereas no benefit was observed in patients with HCV (3.4% vs. 3.9%, P = 0.834). The incidence of secondary outcomes was significantly lower in the rosuvastatin group compared with control group (2.7% vs. 5.3%, P = 0.049) in the overall cohort, but it was similar between the patients with MCV (2.0% vs. 4.2%, P = 0.081) or HCV (5.1% vs. 8.8%, P = 0.273).

Conclusions:

Periprocedural short-term rosuvastatin treatment is effective in reducing CIAKI and adverse clinical events for patients with diabetes and CKD after their exposure to a moderate volume of contrast medium.  相似文献   
93.

Background:

Recent studies reported that percutaneous coronary intervention with stent implantation was safe and feasible for the treatment of left main coronary artery (LMCA) disease in select patients. However, it is unclear whether drug-eluting stents (DESs) have better outcomes in patients with LMCA disease compared with bare-metal stent (BMS) during long-term follow-up in Chinese populations.

Methods:

From a perspective multicenter registry, 1136 consecutive patients, who underwent BMS or DES implantation for unprotected LMCA stenosis, were divided into two groups: 1007 underwent DES implantation, and 129 underwent BMS implantation. The primary outcome was the rate of major adverse cardiac events (MACEs), including cardiovascular (CV) death, myocardial infarction (MI), and target lesion revascularization (TLR) at 5 years postimplantation.

Results:

Patients in the DES group were older and more likely to have hyperlipidemia and bifurcation lesions. They had smaller vessels and longer lesions than patients in the BMS group. In the adjusted cohort of patients, the DES group had significantly lower 5 years rates of MACE (19.4% vs. 31.8%, P = 0.022), CV death (7.0% vs. 14.7%, P = 0.045), and MI (5.4% vs. 12.4%, P = 0.049) than the BMS group. There were no significant differences in the rate of TLR (10.9% vs. 17.8%, P = 0.110) and stent thrombosis (4.7% vs. 3.9%, P = 0.758). The rates of MACE (80.6% vs. 68.2%, P = 0.023), CV death (93.0% vs. 85.3%, P = 0.045), TLR (84.5% vs. 72.1%, P = 0.014), and MI (89.9% vs. 80.6%, P = 0.029) free survival were significantly higher in the DES group than in the BMS group. When the propensity score was included as a covariate in the Cox model, the adjusted hazard ratios for the risk of CV death and MI were 0.41 (95% confidence interval [CI]: 0.21–0.63, P = 0.029) and 0.29 (95% CI: 0.08–0.92, P = 0.037), respectively.

Conclusions:

DES implantation was associated with more favorable clinical outcomes than BMS implantation for the treatment of LMCA disease even though there was no significant difference in the rate of TLR between the two groups.  相似文献   
94.
Insidious brain microinjury from motor vehicle‐induced whole‐body vibration (WBV) has not yet been investigated. For a long time we have believed that WBV would cause cumulative brain microinjury and impair cerebral function, which suggests an important risk factor for motor vehicle accidents and secondary cerebral vascular diseases. Fifty‐six Sprague‐Dawley rats were divided into seven groups (n = 8): 1) 2‐week normal control group, 2) 2‐week sham control group (restrained in the tube without vibration), 3) 2‐week vibration group (exposed to whole‐body vibration at 30 Hz and 0.5g acceleration for 4 hr/day, 5 days/week, for 2 weeks), 4) 4‐week sham control group, 5) 4‐week vibration group, 6) 8‐week sham control group, and 7) 8‐week vibration group. At the end point, all rats were evaluated in behavior, physiological, and brain histopathological studies. The cerebral injury from WBV is a cumulative process starting with vasospasm squeezing of the endothelial cells, followed by constriction of the cerebral arteries. After the 4‐week vibration, brain neuron apoptosis started. After the 8‐week vibration, vacuoles increased further in the brain arteries. Brain capillary walls thickened, mean neuron size was obviously reduced, neuron necrosis became prominent, and wide‐ranging chronic cerebral edema was seen. These pathological findings are strongly correlated with neural functional impairments. © 2014 Wiley Periodicals, Inc.  相似文献   
95.
96.
目的:了解心理资本对青少年抑郁的影响,深入探讨心理资本对抑郁的作用机制。方法采用积极心理资本量表(PPQ)和流调中心用抑郁量表(CES -D)对1200名青少年学生进行问卷调查。结果男生、独生子女、非留守学生及完整家庭学生的心理资本得分相对较高,抑郁得分相对较低,抑郁得分在性别、是否留守、家庭是否完整上差异有统计学意义;抑郁等级(无抑郁、可能有抑郁、抑郁)在心理资本及其4个维度上差异有统计学意义;心理资本及其4个维度(自我效能、韧性、希望、乐观)与抑郁呈显著负相关,4个维度能够解释抑郁水平26%的变异量。结论心理资本对抑郁具有缓解作用。  相似文献   
97.
目的 探讨Ivor-lewis法与右胸-腹部-颈部三切口两种方式治疗中段食管癌的疗效。方法 回顾性分析该院于2009年9月-2012年9月收治的198例中段食管癌患者的临床资料进行分析,其中Ivor-lewis方式手术治疗患者130例,右胸三切口手术治疗患者68例。结果 Ivor-lewis方式治疗的130例患者与运用右胸三切口治疗的68例患者相比,手术时间、乳糜胸发生率、失血量和1及2年生存率差异无统计学意义,但术后住院时间、喉返神经损伤率及吻合口瘘差异均有统计学意义。结论 运用Ivor-lewis方式治疗中段食管癌较传统右胸-腹部-颈部三切口法有一定优势。  相似文献   
98.
Objective: Sirt7, as one of the seven Sirtuin family members, which plays distinct roles in cancer progression, is bringing emerging attention due to its oncogenic characteristic. The expression of Sirt7 in breast cancer remained unclear, and the aim of this study was to elucidate its role in breast cancer. Methods: A total of 188 cases included in this study were immunohistochemically evaluated for Sirt7, and western blot assay was used to assess its expression in breast cell lines as well as 36 breast cancer tissues and 36 paired non-cancerous tissues. Results: Upregulation of Sirt7 was found in breast cancer cell lines and breast cancer tissues (P < 0.001) by western blot analysis. Sirt7 was highly expressed in breast cancer tissue samples (67.8%) compared to adjacent normal breast tissues (31.8%) by immunohistochemical assay. It was also observed that the high expression level of Sirt7 was significantly correlated with high histological grade (P = 0.039) and negatively related to overall survival (P = 0.006). Sirt7 proved to be an independent prognostic factor (P = 0.007) in breast cancer. Conclusions: Sirt7 expression was implicated with high histological grade and independently predicted poor clinical outcome in patients with breast cancer, suggesting that Sirt7 might play a role in the malignant progression of breast cancer.  相似文献   
99.
Objective: To detect the ultrastructural changes in rabbits with type II decompression sickness (DCS), and study the therapeutic effects of hyperbaric oxygen (HBO). Methods: Twenty-seven male New Zealand rabbits were randomly divided equally into the DCS group, HBO treatment group and control group. Experimental models of each group were prepared. Lung apex tissues were harvested to prepare paraffin- and EPON812-embedded tissues. Results: In the DCS group, macroscopic and histological examination revealed severe and rapid damage to lung tissue. Ultrastructural examination revealed exudation of red blood cells in the alveolar space. Type I alveolar epithelial cells exhibited retracted cell processes and swollen mitochondria, and type II cells showed highly swollen mitochondria and decrease in cytoplasmic lamellar bodies. Dilatation and congestion of capillary vessels were accompanied by swelling of endothelial cells and incomplete basement membrane. In the HBO treatment group, the findings were somewhat similar to those in the DCS group, but the extent of damage was lesser. Only a small amount of tiny bubbles could be seen in the blood vessels. Type I alveolar epithelia cells and endothelial cells of the capillaries illustrated slight shortening of cells, swollen cytoplasm and decreased cell processes. Type II alveolar epithelial cells showed slight swelling of the mitochondria, decreased vacuolar degeneration of lamellar bodies, and increase in the number of free ribosomes. Conclusions: Our microscopic and ultrastructural findings confirm that the lung is an important organ affected by DCS. We also confirmed that HBO can alleviate DCS-induced pulmonary damage.  相似文献   
100.
Objective: Long non-coding RNAs (lncRNAs) XIST and HIF1A-AS1 have been shown to play important regulatory roles in cancer biology, and lncRNA-XIST and HIF1A-AS1 are upregulated in several cancers such as glioblastoma, breast cancer and thoracoabdominal aorta aneurysm, however, its value in the diagnosis of non-small cell lung cancer (NSCLC) is unclear. The aim of this study is to evaluate the clinical significance of serum XIST and HIF1A-AS1 as a biomarker in the screening of NSCLC. Methods: Expression levels of lncRNA-XIST and HIF1A-AS1 in tumor tissues and serum from NSCLC patients were evaluated by quantitative real-time PCR, and its association with overall survival of patients was analyzed by statistical analysis. Moreover, the XIST and lncRNA-XIST expression correlation between tumor tissues and plasma was demonstrated by linear regression analysis. Results: The levels of XIST (P < 0.05) and HIF1A-AS1 (P < 0.05) were significantly increased in tumor tissues or serum from NSCLC patients as compared to those of control group. Correlation of lncRNA-XIST or HIF1A-AS1 expression between tumor tissues and serum from the same individuals was confirmed in NSCLC patients. Moreover, serum levels of XIST and HIF1A-AS1 were significantly decreased after surgical treatment as compared to pre-operative. The ROC curves illustrated strong separation between the NSCLC patients and control group, with an AUC of 0.834 (95% CI: 0.726-0.935; P < 0.001) for XIST and 0.876 (95% CI: 0.793-0.965; P < 0.001) for HIF1A-AS1, however, the combination of XIST and HIF1A-AS1 yielded an AUC of 0.931 (95% CI: 0.869-0.990; P < 0.001), which was significantly improved as compared to XIST or HIF1A-AS1 alone. Conclusion: Our results demonstrated that increased serum XIST and HIF1A-AS1 could be used as a predictive biomarker for NSCLC screening, and that combination of XIST and HIF1A-AS1 had a higher positive diagnostic efficiency of NSCLC than XIST or HIF1A-AS1 alone.  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