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   261369篇
  免费   33974篇
  国内免费   10372篇
耳鼻咽喉   1839篇
儿科学   3418篇
妇产科学   5504篇
基础医学   19375篇
口腔科学   2566篇
临床医学   21312篇
内科学   36976篇
皮肤病学   1613篇
神经病学   1966篇
特种医学   8337篇
外国民族医学   262篇
外科学   36132篇
综合类   36882篇
现状与发展   57篇
一般理论   3篇
预防医学   13119篇
眼科学   430篇
药学   20330篇
  159篇
中国医学   9175篇
肿瘤学   86260篇
  2024年   247篇
  2023年   5407篇
  2022年   7723篇
  2021年   13006篇
  2020年   13086篇
  2019年   11758篇
  2018年   11336篇
  2017年   11846篇
  2016年   12998篇
  2015年   14365篇
  2014年   21334篇
  2013年   21047篇
  2012年   17081篇
  2011年   17755篇
  2010年   13072篇
  2009年   13176篇
  2008年   13421篇
  2007年   12704篇
  2006年   11528篇
  2005年   9320篇
  2004年   7706篇
  2003年   6418篇
  2002年   5488篇
  2001年   5006篇
  2000年   4181篇
  1999年   3429篇
  1998年   2776篇
  1997年   2405篇
  1996年   2045篇
  1995年   2042篇
  1994年   1761篇
  1993年   1395篇
  1992年   1240篇
  1991年   1107篇
  1990年   872篇
  1989年   788篇
  1988年   687篇
  1987年   569篇
  1986年   462篇
  1985年   576篇
  1984年   475篇
  1983年   305篇
  1982年   352篇
  1981年   291篇
  1980年   275篇
  1979年   208篇
  1978年   167篇
  1977年   130篇
  1976年   140篇
  1975年   67篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
We aimed to explore the correlation between P27 expression and Helicobacter pylori (H. pylori) infection in gastric cancer, so as to provide evidence for understanding the pathogenesis of gastric cancer caused by H. pylori infection. A total of 82 samples of gastric cancer tissues and 56 samples of tumor-adjacent normal tissues collected from the gastrectomy were enrolled in this study. Then, 14C-urease breathing test was carried out to evaluate the infection of H. pylori in gastric cancer tissues, the expression of P27 in the tissue samples was detected by the immunohistochemistry staining, and the correlation between the H. pylori infection and P27 expression in gastric cancer was analyzed. Of 82 gastric cancer patients, there were 53 patients with H. pylori infection (64.63%). Among the patients with highly or moderately differentiated gastric cancer, the expression of P27 was much higher than that of patients with poorly differentiated gastric cancer (p < 0.01). Besides, comparison of the P27 expression between males and females, among different age groups, tumor sizes, TNM stages, tumor infiltration degrees, or lymph node metastasis, showed no significant differences (p > 0.05). Analysis of the correlation revealed that P27 expression was negatively correlated with the infection of H. pylori (p < 0.01). Multifactorial logistics regression analysis indicated that tumor differentiation was a risk factor of P27-positive expression in gastric cancer tissues (p < 0.01). In addition, P27 expression in the gastric cancer tissues was lower than that in the tumor-adjacent normal tissues (p < 0.01). In gastric cancer patients, expression of P27 is correlated with H. pylori infection which, via downregulating P27, can cause the cancerization of gastric mucosa, and P27, for its role in the development and progression of gastric cancer, is a potential auxiliary indicator for clinical diagnosis whether gastric cancer is complicated with H. pylori infection. So, P27 is a key indicator for diagnosis, treatment, and prognostic evaluation of disease in the advanced stage.  相似文献   
62.
There is growing, but inconsistent evidence suggesting oestrogen may play a key role in lung cancer development, especially among never-smoking women for whom lung cancer risk factors remain largely elusive. Using the China Kadoorie Biobank, a large-scale prospective cohort with 302 510 women aged 30 to 79 years recruited from 10 regions in China during 2004 to 2008, we assessed the risk of lung cancer death among self-reported never-smoking women who were cancer-free at baseline, in relation to age at menarche, age at menopause, time since menopause, prior use of oral contraceptives (OCP), number of livebirths, breastfeeding and age at first livebirth. Women were followed up to December 31, 2016 with linkage to mortality data. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox regression, adjusting for key confounders including several socio-demographic, environmental and lifestyle factors. Among 287 408 never-smoking women, 814 died from lung cancer with a median follow-up of 10.3 years. Women who had used OCP within 15 years prior to baseline had a significantly higher hazard of lung cancer death compared with never-users: HR = 1.85 (95% CI: 1.14-3.00) and risk increased by 6% with each additional year of use: HR = 1.06 (1.01-1.10). Among parous women, the hazard of lung cancer death increased by 13% with each single livebirth: HR = 1.13 (1.05-1.23); and among post-menopausal women, the risk increased by 2% with each year since menopause: HR = 1.02 (1.01-1.04). These results suggest that reproductive factors which were proxies for lower endogenous oestrogen level, for example, longer duration of OCP use, could play a role in lung cancer development.  相似文献   
63.
64.
吴文昊  李兴 《现代肿瘤医学》2022,(21):4022-4026
肝X受体(liver X receptors,LXRs)是孤儿核受体转录因子超家族成员,当LXRs被激活后,可调节靶基因的转录表达,不但参与胆固醇、脂肪、糖的代谢以及炎症等过程,并且在许多恶性肿瘤组织中均有表达。为全面了解肝X受体激动剂在治疗癌症中的研究现状,本文将从肝X受体激动剂与胃癌、肝癌、卵巢癌、乳腺癌、子宫内膜癌、肺癌以及结直肠癌的相关性方面进行综述。  相似文献   
65.
ObjectivesTo examine the impact of time to surgery (TTS) on survival among patients with stage I non-small cell lung cancer (NSCLC).MethodsAll patients in the Canadian province of Ontario with stage I NSCLC from 2007 to 2017 were included. A logistic regression identified the predictors of TTS and a flexible parametric model estimated survival rates based on TTS.ResultsOver the study period, 6428 patients with stage I NSCLC undergoing surgical resection were identified, of which 62.5% had TTS >28 days. Less than half these patients (40.8%) underwent open resection, with 19.3% undergoing open sublobar and 21.5% undergoing open lobectomy. Adenocarcinoma and squamous cell carcinoma tumors accounted for 33.3% and 22.0% of cases, respectively. The majority (85.6%) of patients lived in urban areas within 50 km of a regional cancer center (76.9%). Variables that predicted TTS >28 days include age and extent of resection. After adjustment for VATS vs. open resection, age, sex, frailty, year of diagnosis, histology of tumor, and extent of resection, the hazard ratio for TTS >28 days was 1.26 (95%CI:1.13–1.40), indicating a 26% increased risk of all-cause mortality (p < 0.0001). The highest 5-year survival was observed for patients with stage I disease undergoing resection within 28 days.ConclusionsThe present study found age and extent of resection to be associated with increased TTS. Importantly, patients with TTS >28 days had reduced long-term survival.  相似文献   
66.
The use of radiation for primary liver cancers has historically been limited because of the risk of radiation-induced liver disease. Treatment fields have become more conformal because of several technical advances, and this has allowed for dose escalation. Stereotactic body radiation therapy (SBRT), also known as stereotactic ablative radiotherapy, is now able to safely treat liver tumors to ablative doses while sparing functional liver parenchyma by using highly conformal therapy. Several retrospective and small prospective studies have examined the use of SBRT for liver cancers; however, there is a lack of well-powered randomized studies to definitively guide management in these settings. Recent advances in systemic therapy for primary liver cancers have improved outcomes; however, the optimal selection criteria for SBRT as a local therapy remain unclear among other liver-directed options such as radiofrequency ablation, transarterial chemoembolization, and radioembolization.  相似文献   
67.
Hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer is defined by the presence of the estrogen receptor and/or the progesterone receptor and the absence of HER2 gene amplification. HR-positive/HER2-negative breast cancer accounts for 65%–70% of all breast cancers, and incidence increases with increasing age. Treatment varies by stage, and endocrine therapy is the mainstay of treatment in both early stage and late-stage disease. Combinations with cyclin-dependent kinase 4/6 inhibitors have reduced distant recurrence in the early stage setting and improved overall survival in the metastatic setting. Chemotherapy is used based on stage and tumor biology in the early stage setting and after endocrine resistance for advanced disease. New therapies, including novel endocrine agents and antibody-drug conjugates, are now changing the treatment landscape. With the availability of new treatment options, it is important to define the optimal sequence of treatment to maximize clinical benefit while minimizing toxicity. In this review, the authors first discuss the pathologic and molecular features of HR-positive/HER2-negative breast cancer and mechanisms of endocrine resistance. Then, they discuss current and emerging therapies for both early stage and metastatic HR-positive/HER2-negative breast cancer, including treatment algorithms based on current data.  相似文献   
68.
69.
This study aimed to clarify the characteristics of patients with lung cancer undergoing treatment until the onset of tuberculosis. Between 2005 and 2019, patients who were admitted to Tokyo National Hospital due to tuberculosis during lung cancer treatment were examined retrospectively. There were 42 patients, and detailed medical information was obtained in 39 patients. The median age of the 39 patients were 75 years (range: 47–92 years), of which 33 were males and 36 were Japanese Baby Boomers or older. Regarding risk factors for developing tuberculosis, smoking was noted in 34 cases, oral corticosteroid use in 13, and previous tuberculosis in six. Thirty-seven patients had one risk factor and 19 had two or more risk factors, but diagnosis of latent tuberculosis infection (LTBI) was obtained in only one patients, and none had received LTBI treatment. The first-line treatment for lung cancer was resection in 13 cases, chemoradiotherapy in 6, chemotherapy in 10, radiation therapy in 3, laser therapy in 1, and best supportive care (BSC) alone in 6. At tuberculosis onset, BSC accounted for 17 cases, but other situations were considerably existed such as anticancer medication (12 cases), and observation after lung cancer treatment (10 cases). Tuberculosis occurred in various situations in elderly patients with lung cancer. It is critical to actively evaluate the risk of tuberculosis and consider LTBI screening and treatment.  相似文献   
70.
目的:探讨人胃癌细胞中乙酰肝素酶(HPSE)调控的差异蛋白和信号通路,为以HPSE为靶点防治胃癌提供依据。方法:利用siRNA干扰技术,在乙酰肝素酶(HPSE)基因高表达的SGC7901细胞中转入干扰HPSE的慢病毒载体(LV-HPSE-RNAi),通过嘌呤霉素筛选出稳定株,利用qPCR和Western blot分别检测HPSE mRNA和蛋白表达;利用细胞划痕实验和Transwell侵袭实验测定细胞的迁移和侵袭能力;利用同位素标记的相对和绝对定量(iTRAQ)联合二维液相色谱串联质谱(2DLC-MS/MS)技术筛查差异蛋白,并进行生物信息学分析,对差异蛋白PKCa应用Western blot进一步验证。结果:人胃癌SGC7901细胞和沉默HPSE表达的ZSGC7901细胞对比检测出98个差异蛋白,并且富集在157条信号通路上。与肿瘤发生发展关系密切的有6条:细胞外基质和受体相互作用、局灶性黏附、PI3K-Akt信号通路、癌途径、癌中microRNAs、Wnt信号通路。且上调的FAK、ITGA、PKCa等蛋白和下调的PKA、CDK6等蛋白在通路中处于重要的位置。Western blot结果证明PKCa在沉默HPSE的ZSGC7901细胞中表现为上调,差异具有统计学意义(P<0.05),与蛋白质组学筛选结果一致。结论:HPSE在人胃癌细胞中调控的蛋白,参与细胞重要生物学过程、参与重要分子功能及重要信号途径,有望可以成为防治胃癌的新靶点。  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