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   1599008篇
  免费   134162篇
  国内免费   2589篇
耳鼻咽喉   21824篇
儿科学   53013篇
妇产科学   46338篇
基础医学   226892篇
口腔科学   47331篇
临床医学   141014篇
内科学   313739篇
皮肤病学   34181篇
神经病学   130174篇
特种医学   64914篇
外国民族医学   474篇
外科学   244254篇
综合类   39881篇
现状与发展   3篇
一般理论   547篇
预防医学   122903篇
眼科学   36500篇
药学   121551篇
  2篇
中国医学   2881篇
肿瘤学   87343篇
  2018年   14908篇
  2016年   13021篇
  2015年   15163篇
  2014年   20840篇
  2013年   31715篇
  2012年   43011篇
  2011年   45239篇
  2010年   26593篇
  2009年   25536篇
  2008年   43411篇
  2007年   45734篇
  2006年   46492篇
  2005年   45144篇
  2004年   44549篇
  2003年   42537篇
  2002年   41605篇
  2001年   75720篇
  2000年   78287篇
  1999年   66112篇
  1998年   16802篇
  1997年   15419篇
  1996年   15358篇
  1995年   16015篇
  1994年   15052篇
  1993年   14236篇
  1992年   55485篇
  1991年   53877篇
  1990年   52643篇
  1989年   50900篇
  1988年   47274篇
  1987年   46627篇
  1986年   44341篇
  1985年   42935篇
  1984年   32115篇
  1983年   27638篇
  1982年   16201篇
  1981年   14486篇
  1980年   13578篇
  1979年   30496篇
  1978年   21120篇
  1977年   17763篇
  1976年   16726篇
  1975年   17580篇
  1974年   21518篇
  1973年   20693篇
  1972年   18889篇
  1971年   17775篇
  1970年   16308篇
  1969年   15276篇
  1968年   13982篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.

Objectives

Anti–programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) immunotherapy has demonstrated success in the treatment of advanced NSCLC. Recently, PD-1/PD-L1 blockade also has demonstrated interesting results in small trials of neoadjuvant treatment in stage IB to IIIA NSCLC. In addition, several clinical trials using anti–PD-1/PD-L1 immunotherapy as an adjuvant or neoadjuvant treatment in patients with resectable stage NSCLC are ongoing. However, few analyses of anti–PD-1/PD-L1 immunotherapy–related biomarkers in early-stage squamous cell lung carcinoma (SqCLC) have been reported. In this study, we evaluated PD-L1 protein expression, tumor mutation burden, and expression of an immune gene signature in early-stage SqCLC, providing data for identifying the potential role for patients with anti–PD-1/PD-L1 treatment in early-stage SqCLC.

Methods

A total of 255 specimens from patients with early-stage SqCLC were identified within participating centers of the Strategic Partnering to Evaluate Cancer Signatures program. PD-L1 protein expression by immunohistochemistry was evaluated by using the Dako PD-L1 22C3 pharmDx kit on the Dako Link 48 auto-stainer (Dako, Carpinteria, CA). Tumor mutation burden (TMB) was calculated on the basis of data from targeted genome sequencing. The T-effector and interferon gamma (IFN-γ) gene signature was determined from Affymetrix gene chip data (Affymetrix, Santa Clara, CA) from frozen specimens.

Results

The prevalence of PD-L1 expression was 9.8% at a tumor proportion score cutoff of at least 50%. PD-L1 mRNA and programmed cell death 1 ligand 2 mRNA positively correlated with PD-L1 protein expression on tumor cells (TCs) and tumor-infiltrating immune cells. PD-L1 protein expression on tumor-infiltrating immune cells was correlated with the T-effector and IFN-γ gene signature (p < 0.001), but not with TMB. For TCs, all of these biomarkers were independent of each other and neither PD-L1 protein expression, TMB, or T-effector and IFN-γ gene signatures were independently prognostic for patient outcomes.

Conclusions

Evaluation of PD-L1 expression, TMB, and T-effector and IFN-γ gene signatures in the cohort with early-stage SqCLC found them to be independent of each other, and none was associated with overall survival. Our results also support the hypothesis that PD-L1 expression is regulated by an intrinsic mechanism on TCs and an adaptive mechanism on immune cells.  相似文献   
82.
Uptake of colorectal cancer screening remains suboptimal. Mailed fecal immunochemical testing (FIT) offers promise for increasing screening rates, but optimal strategies for implementation have not been well synthesized. In June 2019, the Centers for Disease Control and Prevention convened a meeting of subject matter experts and stakeholders to answer key questions regarding mailed FIT implementation in the United States. Points of agreement included: 1) primers, such as texts, telephone calls, and printed mailings before mailed FIT, appear to contribute to effectiveness; 2) invitation letters should be brief and easy to read, and the signatory should be tailored based on setting; 3) instructions for FIT completion should be simple and address challenges that may lead to failed laboratory processing, such as notation of collection date; 4) reminders delivered to initial noncompleters should be used to increase the FIT return rate; 5) data infrastructure should identify eligible patients and track each step in the outreach process, from primer delivery through abnormal FIT follow-up; 6) protocols and procedures such as navigation should be in place to promote colonoscopy after abnormal FIT; 7) a high-quality, 1-sample FIT should be used; 8) sustainability requires a program champion and organizational support for the work, including sufficient funding and external policies (such as quality reporting requirements) to drive commitment to program investment; and 9) the cost effectiveness of mailed FIT has been established. Participants concluded that mailed FIT is an effective and efficient strategy with great potential for increasing colorectal cancer screening in diverse health care settings if more widely implemented.  相似文献   
83.
Liu  R.  Zhou  J.  Xia  S.  Li  T. 《Clinical & translational oncology》2020,22(5):694-702
Clinical and Translational Oncology - The specific association between PTEN deletion or ERG rearrangement and the recurrence of prostate cancer (PC) treated with radical prostatectomy (RP) or...  相似文献   
84.
Background: Uterine fibroids are a common type of solid tumor presenting in women of reproductive age. There are very few alternative treatment available from conventional treatment involving surgeries. Labisia pumila var. alata or locally known as ‘Kacip Fatimah’ was widely used as traditional medicine in Malaysia. This plant has been used to maintain a healthy female reproductive system. The present study aimed to evaluate anti fibroid potential of L. pumila extracts through in vitro apoptosis activity against uterine leiomyoma cells (SK-UT-1) and in uterine leiomyoma xenograft model. Evaluation of bioactive markers content were also carried out. Methods: Apoptotic induction of the extracts was determined by morphological examination of AO/PI dual staining assay by flourescent microscopy and flow cytometry analysis on Annexin V-FITC/PI stained cells. In vivo study was done in immune-compromised mouse xenograft model. HPLC analysis was employed to quantify marker compounds. Results: Morphological analysis showed L. pumila induced apoptosis in a dose dependent manner against SK-UT-1 cells. In vivo study indicated that L. pumila significantly suppressed the growth of uterine fibroid tumor. All tested extracts contain bioactive marker of gallic acid and cafeic acid. Conclusion: This work provide significant data of the potential of L. pumila in management of uterine fibroids.  相似文献   
85.
86.
Non‐melanoma skin cancer frequently results from chronic exposure to ultraviolet (UV) irradiation. UV‐induced DNA damage activates cell cycle arrest checkpoints through degradation of the cyclin‐dependent kinase activators, the cell division cycle 25 (CDC25) phosphatases. We previously reported increased CDC25A in nonmelanoma skin cancer, but CDC25B and CDC25C had not been previously examined. Consequently, we hypothesized that increased expression of CDC25B and CDC25C increases tumor cell proliferation and skin tumor growth. We found that CDC25B and CDC25C were increased in mouse and human skin cancers. CDC25B was primarily cytoplasmic in skin and skin tumors and was significantly increased in the squamous cell carcinoma (SCC), while CDC25C was mostly nuclear in the skin, with an increased cytoplasmic signal in the premalignant and malignant tumors. Surprisingly, forced expression of CDC25B or CDC25C in cultured SCC cells did not affect proliferation, but instead suppressed apoptosis, while CDC25C silencing increased apoptosis without impacting proliferation. Targeting CDC25C to the nucleus via mutation of its nuclear export sequence, however, increased proliferation in SCC cells. Overexpression of CDC25C in the nuclear compartment did not hinder the ability of CDC25C to suppress apoptosis, neither did mutation of sites necessary for its interaction with 14‐3‐3 proteins. Analysis of apoptotic signaling pathways revealed that CDC25C increased activating phosphorylation of Akt on Ser473, increased inhibitory phosphorylation of proapoptotic BAD on Ser136, and increased the survival protein Survivin. Silencing of CDC25C significantly reduced Survivin levels. Taken together, these data suggest that increased expression of CDC25B or CDC25C are mechanisms by which skin cancers evade apoptotic cell death.  相似文献   
87.
Posaconazole is indicated for prophylaxis and treatment of invasive aspergillosis. Therapeutic drug monitoring (TDM) of posaconazole is used to optimise drug exposure. The aim of this study was to analyse and describe the TDM practices and exposure of posaconazole tablets. Patients who received posaconazole for treatment or prophylaxis of fungal infections were included in the study. The following therapeutic window was defined: if concentration was low (<0.7 mg/L for prophylaxis or < 1.5 mg/L for treatment) or high (>3.75 mg/L), the hospital pharmacist provided the physician with dosage advice, which implementation to patient care was analysed. A longitudinal analysis was performed to analyse if different confounding variables had an effect on posaconazole concentrations. Forty‐seven patients were enrolled resulting in 217 posaconazole trough concentrations. A median of 3 (IQR 1‐7) samples was measured per patient. The median concentration was 1.7 mg/L (IQR 0.8‐2.7) for prophylaxis and 1.76 mg/L (IQR 1.3‐2.3) for treatment. Overall, 78 posaconazole concentrations were out of the therapeutic window. For 45 (54%) of these concentrations, a dosage change was recommended. In the longitudinal analysis, the laboratory markers and patient baseline variables did not have an effect on posaconazole concentrations. Adequate posaconazole exposure was shown in 64% (affected 28 patients) of the measured concentrations. TDM practice of posaconazole can be improved by increasing the implementation rate of dose recommendation by a multidisciplinary antifungal stewardship team.  相似文献   
88.
89.
Glioblastoma multiforme (GBM) is the most common and aggressive malignant type of brain tumor. Despite advances in diagnosis and therapy, the prognosis of  相似文献   
90.
In recent years, a robust body of scholarship has emerged that examines ethical challenges facing the learning health organization model. In “Bystander Ethics and Good Samaritanism,” James Sabin and colleagues make a valuable addition to this scholarship, identifying and exploring the important question of what researchers' obligations are to patients receiving “usual care” if “that care is seen as suboptimal.” The central issue that Sabin et al. faced was whether it would be acceptable for researchers to identify patients with untreated atrial fibrillation but then assign them to a control group that would not receive education about the importance of oral anticoagulation. The authors present this challenge as an issue of “bystander ethics.” To avoid being “bystanders” to identified instances of suboptimal care, the research team decided to instead identify a “delayed intervention” group for which they would not determine the members' anticoagulation status, thereby preventing them from knowing that specific patients met the criteria for oral anticoagulants but were not using them. This “workaround” approach strikes me as disingenuous.  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