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   238886篇
  免费   13120篇
  国内免费   6886篇
耳鼻咽喉   3253篇
儿科学   8704篇
妇产科学   4071篇
基础医学   16951篇
口腔科学   4673篇
临床医学   28776篇
内科学   42959篇
皮肤病学   3139篇
神经病学   11603篇
特种医学   12483篇
外国民族医学   24篇
外科学   39024篇
综合类   21388篇
现状与发展   27篇
预防医学   15421篇
眼科学   5056篇
药学   24396篇
  166篇
中国医学   4849篇
肿瘤学   11929篇
  2023年   2320篇
  2022年   5100篇
  2021年   11100篇
  2020年   6146篇
  2019年   11815篇
  2018年   6435篇
  2017年   5582篇
  2016年   7511篇
  2015年   10393篇
  2014年   18936篇
  2013年   16657篇
  2012年   19688篇
  2011年   16564篇
  2010年   15240篇
  2009年   14772篇
  2008年   13383篇
  2007年   13386篇
  2006年   11307篇
  2005年   7606篇
  2004年   3962篇
  2003年   3477篇
  2002年   2802篇
  2001年   2252篇
  2000年   1977篇
  1999年   1295篇
  1998年   1754篇
  1997年   1600篇
  1996年   1322篇
  1995年   1294篇
  1994年   1278篇
  1993年   1010篇
  1992年   1237篇
  1991年   1069篇
  1990年   1101篇
  1989年   1074篇
  1988年   1002篇
  1987年   876篇
  1986年   709篇
  1985年   1637篇
  1984年   1792篇
  1983年   1287篇
  1982年   1379篇
  1981年   1358篇
  1980年   1167篇
  1979年   1006篇
  1978年   774篇
  1977年   773篇
  1976年   669篇
  1975年   444篇
  1974年   457篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
目的:探讨微小RNA-942-5p(miR-942-5p)在肝细胞癌(HCC)组织中的表达及其功能。方法:用实时定量PCR检测西安交通大学第一附属医院样本库保存的73例HCC组织和对应癌旁组织中miR-942-5p的表达。分析miR-942-5p表达与HCC患者临床病理资料的关系,同时分析TCGA数据库中miR-942-5p表达与HCC患者总生存率的关系。Transwell小室检测干扰miR-942-5p表达后HCC细胞迁移和侵袭能力的变化,StarBase V3.0网站和荧光素酶报告基因质粒预测分析miR-942-5p的下游靶点,并用Western blot验证。结果:miR-942-5p表达量在HCC组织中明显高于对应癌旁组织(2.390 vs. 1.764,P0.05)。miR-942-5p表达量与HCC患者肿瘤数目、血管浸润和临床分期明显有关(均P0.05)。miR-942-5p高表达HCC患者总生存率明显低于miR-942-5p低表达HCC患者(19.535%vs. 53.873%,P0.05)。沉默miR-942-5p表达后,肝癌HCCLM3和MHCC97H细胞迁移和侵袭能力明显减弱(均P0.05)。预测与分析结果显示,扣针蛋白5(FBLN5)是miR-942-5p的直接下游靶点(P0.05),沉默miR-942-5p表达导致HCCLM3和MHCC97H细胞中FBLN5表达增加。结论:miR-942-5p在HCC组织中表达异常升高并与恶性临床特征和不良预后密切相关,机制可能与miR-942-5p抑制FBLN5表达促进HCC细胞迁移和侵袭有关。  相似文献   
92.

Background

Persistent iatrogenic atrial septal defect (iASD) is a common but poorly characterized complication after cryoballoon (CB) pulmonary vein isolation (PVI) procedures. We therefore investigate its prevalence, evolution, risk factors, and clinical outcomes in a prospective longitudinal study.

Methods

A total of 108 patients (41 women, mean age 57 ± 11.3) underwent CB PVI for AF. Serial transesophageal echocardiography (TEE) was performed 9 months and then annually until 6 years after the procedure to study the characteristics of persistent iASD.

Results

Persistent iASD occurred in 33 (30.6%) patients 9 months after CB PVI. Spontaneous closure of iASD was found in 6 (22.2%) and 3 (15.8%) patients 2 and 3 years after the procedures, respectively. No spontaneous closure was observed on 4, 5, and 6-year TEE follow-up. The projected long-term persistence rate of iASD after CB PVI was therefore 20% (30.6% × 0.778 × 0.842). Using multivariate logistic regression, a higher number of cryoapplications (≥ 2 minutes) was the only independent predictor of persistent iASD 9 months after CB PVI (odds ratio [OR] 1.207; 95% confidence interval [CI], 1.033-1.411, P = 0.018). Two (1.9%) patients with significantly larger iASD size than the others (long diameter 12.6 ± 0.8 vs 3.7 ± 1.5 mm, P < 0.001; short diameter 10.9 ± 0.2 vs 3 ± 1.1 mm, P < 0.001) required percutaneous closure because of exertional dyspnea and right ventricular enlargement. Over 129.7 patient-years follow-up, during which iASD persisted, there was no occurrence of neurologic events.

Conclusions

Approximately one fifth of patients undergoing CB PVI will have permanently persistent iASD. Patients with defect sizes of greater than 10 mm may need percutaneous closure due to significant left-to-right shunting.  相似文献   
93.
Ovarian carcinoma is one of the most lethal malignancies, but only very few prognostic biomarkers are known. The degradome, comprising proteases, protease non-proteolytic homologues and inhibitors, have been involved in the prognosis of many cancer types, including ovarian carcinoma. The prognostic significance of the whole degradome family has not been specifically studied in high-grade serous ovarian cancer. A targeted DNA microarray known as the CLIP-CHIP microarray was used to identify potential prognostic factors in ten high-grade serous ovarian cancer women who had early recurrence (<1.6 years) or late/no recurrence after first line surgery and chemotherapy. In women with early recurrence, we identified seven upregulated genes (TMPRSS4, MASP1/3, SPC18, PSMB1, IGFBP2, CFI – encoding Complement Factor I – and MMP9) and one down-regulated gene (ADAM-10). Using immunohistochemistry, we evaluated the prognostic effect of these 8 candidate genes in an independent cohort of 112 high-grade serous ovarian cancer women. Outcomes were progression, defined according to CA-125 criteria, and death. Multivariate Cox proportional hazard regression models were done to estimate the associations between each protein and each outcome. High ADAM-10 expression (intensity of 2–3) was associated with a lower risk of progression (adjusted hazard ratio (HR): 0.51; 95% confidence interval (CI): 0.29-0.87). High complement factor I expression (intensity 2–3) was associated with a higher risk of progression (adjusted HR: 2.30, 95% CI: 1.17–4.53) and death (adjusted HR: 3.42; 95% CI: 1.72–6.79). Overall, we identified the prognostic value of two proteases, ADAM-10 and complement factor I, for high-grade serous ovarian cancer which could have clinical significance.  相似文献   
94.
IntroductionMajor hepatectomy (MH) is often needed in the curative management of intrahepatic cholangiocarcinoma (IHCC) and colorectal liver metastases (CRLM). While similar outcomes could be expected after MH for IHCC and CRLM, outcomes seem worse after MH for IHCC. A better understanding of such differences might help improving perioperative outcomes but comprehensive analysis are lacking.MethodsAll patients undergoing curative intent MH for IHCC or CRLM from 2003 to 2009 were included from two dedicated multi-institutional datasets. Preoperative management and short-term outcomes after MH were first compared. Independent predictors of postoperative mortality and morbidity were identified.ResultsAmong 827 patients, 333 and 494 patients underwent MH for IHCC and CRLM, respectively. Preoperative portal vein embolization was more frequently performed in the CRLM group (p < 0.001). MH in the IHCC group required more extended resection (p < 0.001). Postoperative mortality and severe morbidity rates were significantly higher in the IHCC group (7.2% vs. 1.2% and 29.7% vs. 11.1%, p < 0.001, respectively). Main causes for mortality were postoperative liver failure and deep surgical site infection. MH for IHCC was an independent risk factor for mortality (p < 0.001) and severe morbidity (p < 0.001). After propensity score matching (212 patients in each group), the aforementioned differences regarding outcomes remained statistically significant.ConclusionThis study suggests that IHCC patients are inherently more at risk after MH as compared to CRLM patients. Considering that postoperative liver failure was the most frequent cause of death, preoperative planning might have been inadequate in the setting of IHCC while more complex/extended resections should be expected.  相似文献   
95.
96.
ImportanceImmunotherapy has emerged as an effective treatment option for the management of advanced cancers. The effects of these immune checkpoint inhibitors in the older patient population has not been adequately assessed.ObjectiveTo understand the impact of aging on CTLA-4 and PDL-1 inhibitors efficacy and immune-related adverse events (irAE) in the context of real-world management of advanced solid cancers.Design, Setting, and ParticipantsThis retrospective study involved all non-study patients with histologically-confirmed metastatic or inoperable solid cancers receiving immunotherapy at Kingston Health Sciences Centre. We defined ‘older patient’ as age ≥ 75. All statistical analyses were conducted under SPSS IBM for Windows version 24.0.Main Outcomes and MeasuresStudy outcomes included immunotherapy treatment response, survival, as well as number, type, and severity of irAEs.ResultsOur study (N = 78) had 29 (37%) patients age <65, 26 (33%) patients age 65–74, and 23 (30%) patients age ≥75. Melanoma, non-small cell lung cancer, and renal cell carcinoma accounted for 70%, 22%, and 8% of the study population, respectively. Distributions of ipilimumab (32%), nivolumab (33%), and pembrolizumab (35%) were similar in the study. The response rates were 28%, 27%, and 39% in the age <65, age 64–74, age ≥75 groups, respectively (P = 0.585). Kaplan-Meier curve showed a median survival of 28 months (12.28–43.9, 95% CI) and 17 months (0–36.9, 95% CI) in the age <65 and age 64–74 groups, respectively; the estimated survival probability did not reach 50% in the age ≥75 group (P = 0.319). There were no statistically significant differences found in terms of irAEs, multiple irAEs, severity of grade 3 or higher, types of irAEs, and irAEs resolution status when comparing between different age groups.Conclusion and RelevanceOur results suggest that patients age ≥75 are able to gain as much benefit from immunotherapy as younger patients, without excess toxicity. Our findings suggest that single agent immunotherapy is generally well-tolerated across different age groups with no significant difference in the type, frequency or severity of irAEs. Future studies evaluating aging and combination immunotherapy are warranted.  相似文献   
97.
《Drug discovery today》2022,27(6):1733-1742
Compounds that exhibit assay interference or undesirable mechanisms of bioactivity are routinely encountered in assays at various stages of drug discovery. We observed that assays for the investigation of thiol-reactive and redox-active compounds have not been collected in a comprehensive review. Here, we review these assays and subject them to experimental optimization to improve their reliability. We demonstrate the usefulness of our assay cascade by assaying a library of bioactive compounds, chemical probes, and a set of approved drugs. These high-throughput assays should complement the array of wet-lab and in silico assays during the initial stages of hit discovery campaigns to pursue only hit compounds with tractable mechanisms of action.  相似文献   
98.
This article begins with an overview of the knowledge translation (KT) process, introduces commonly used KT terms and the Aware-Adopt-Adapt (A3) KT map. The A3 was created by a nurse practitioner (NP) for practitioners and NP students to provide a map for those who wish to move existing knowledge to practice, yet do not know where to start or do not have the time to take a deeper dive into specific KT theories.  相似文献   
99.
100.
PurposeWe previously demonstrated that the functional inactivation of DAL-1 and TOB1 promotes an aggressive phenotype in gastric cancer cells, but the links between both genes and the survival of patients with gastric cancer are unknown. Here, we investigated the correlations of the expression levels of DAL-1 and TOB1 with the progression of gastric cancer.MethodsA total of 270 patients who underwent resectable gastrectomy were included. The expression of DAL-1 and TOB1 was detected by immunohistochemistry.ResultsLow expression of DAL-1 in cancer tissue was significantly associated with tumor site (p < 0.05), histological grade (p < 0.01), depth of invasion (p < 0.05), lymph node metastasis status (p < 0.05), Lauren classification (p < 0.001), and clinical stage (p < 0.01). A lower level of TOB1 was observed in gastric cancer patients with diffuse type disease compared to patients with either intestinal or mixed type disease (p < 0.001). Additionally, Spearman’s correlation analysis revealed that decreased expression of DAL-1 was positively correlated with low TOB1 expression (r=0.304, p < 0.001). The survival analysis showed that low levels of DAL-1 and TOB1 were significantly associated with poor survival of gastric cancer patients (p <0.001 and p < 0.05, respectively).ConclusionThe downregulation of DAL-1 and TOB1 expression is associated with shorter survival of gastric cancer patients. Hence, DAL-1 and TOB1 may be considered potential novel markers for predicting the outcomes of patients with gastric cancer.  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