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   934970篇
  免费   67711篇
  国内免费   4953篇
耳鼻咽喉   12760篇
儿科学   29165篇
妇产科学   26585篇
基础医学   130863篇
口腔科学   25474篇
临床医学   79457篇
内科学   187773篇
皮肤病学   19380篇
神经病学   73062篇
特种医学   37833篇
外国民族医学   353篇
外科学   146038篇
综合类   25803篇
现状与发展   12篇
一般理论   260篇
预防医学   67110篇
眼科学   21362篇
药学   67605篇
  56篇
中国医学   4166篇
肿瘤学   52517篇
  2021年   8118篇
  2019年   7835篇
  2018年   10523篇
  2017年   8495篇
  2016年   8925篇
  2015年   10607篇
  2014年   14720篇
  2013年   21400篇
  2012年   28695篇
  2011年   30600篇
  2010年   18711篇
  2009年   17574篇
  2008年   28286篇
  2007年   29819篇
  2006年   30033篇
  2005年   29249篇
  2004年   27596篇
  2003年   26586篇
  2002年   25986篇
  2001年   42132篇
  2000年   43289篇
  1999年   37048篇
  1998年   10466篇
  1997年   9611篇
  1996年   9442篇
  1995年   8761篇
  1994年   8400篇
  1993年   7763篇
  1992年   28407篇
  1991年   27141篇
  1990年   26530篇
  1989年   25509篇
  1988年   23656篇
  1987年   23273篇
  1986年   22287篇
  1985年   21200篇
  1984年   15820篇
  1983年   13469篇
  1982年   8072篇
  1979年   14585篇
  1978年   10188篇
  1977年   8605篇
  1976年   8124篇
  1975年   8940篇
  1974年   10684篇
  1973年   10169篇
  1972年   9659篇
  1971年   8909篇
  1970年   8575篇
  1969年   8014篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Kinase alterations are increasingly recognised as oncogenic drivers in mesenchymal tumours. Infantile fibrosarcoma and the related renal tumour, congenital mesoblastic nephroma, were among the first solid tumours shown to harbour recurrent tyrosine kinase fusions, with the canonical ETV6::NTRK3 fusion identified more than 20 years ago. Although targeted testing has long been used in diagnosis, the advent of more robust sequencing techniques has driven the discovery of kinase alterations in an array of mesenchymal tumours. As our ability to identify these genetic alterations has improved, as has our recognition and understanding of the tumours that harbour these alterations. Specifically, this study will focus upon mesenchymal tumours harbouring NTRK or other kinase alterations, including tumours with an infantile fibrosarcoma-like appearance, spindle cell tumours resembling lipofibromatosis or peripheral nerve sheath tumours and those occurring in adults with a fibrosarcoma-like appearance. As publications describing the histology of these tumours increase so, too, do the variety kinase alterations reported, now including NTRK1/2/3, RET, MET, RAF1, BRAF, ALK, EGFR and ABL1 fusions or alterations. To date, these tumours appear locally aggressive and rarely metastatic, without a clear link between traditional features used in histological grading (e.g. mitotic activity, necrosis) and outcome. However, most of these tumours are amenable to new targeted therapies, making their recognition of both diagnostic and therapeutic import. The goal of this study is to review the clinicopathological features of tumours with NTRK and other tyrosine kinase alterations, discuss the most common differential diagnoses and provide recommendations for molecular confirmation with associated treatment implications.  相似文献   
2.
中医学古籍中罕有关于“胰腺”的明确记载,缺乏直观、系统的理论论述。本文试图通过对各个时期具有代表性的医学典籍所记载内容的分析,结合现代解剖学相关理论,梳理中医学对胰腺实体解剖的认识过程。通过分析,笔者认为中医学对胰腺实体解剖的认识具有阶段性:①先秦两汉时期,存在胰腺实体解剖,但并非认为胰腺是脏器;②唐宋时期,胰腺实体解剖更加清晰,在医学上胰腺附属于脾,并非为独立的脏器;③明清时期,胰腺实体解剖明确,部分医家以独立脏器论之,出现“脾”、“胰”之争。中医学理论缺少对胰腺的单独论述,目前学界的主流观点多为“胰属脾”,线性归属以脾笼统代之略显单薄,不利于理论的丰富与发展。笔者认为胰腺藏象应独立于脾单独讨论,现代解剖学对胰腺命名同一,形态结构清楚,位置描述明确,可直接补充进中医学胰腺藏象(藏)理论中,为完善胰腺藏象理论搭建解剖学基础。  相似文献   
3.
4.
5.
6.
7.
Gestational trophoblastic neoplasia (GTN) patients are treated according to the eight-variable International Federation of Gynaecology and Obstetrics (FIGO) scoring system, that aims to predict first-line single-agent chemotherapy resistance. FIGO is imperfect with one-third of low-risk patients developing disease resistance to first-line single-agent chemotherapy. We aimed to generate simplified models that improve upon FIGO. Logistic regression (LR) and multilayer perceptron (MLP) modelling (n = 4191) generated six models (M1-6). M1, all eight FIGO variables (scored data); M2, all eight FIGO variables (scored and raw data); M3, nonimaging variables (scored data); M4, nonimaging variables (scored and raw data); M5, imaging variables (scored data); and M6, pretreatment hCG (raw data) + imaging variables (scored data). Performance was compared to FIGO using true and false positive rates, positive and negative predictive values, diagnostic odds ratio, receiver operating characteristic (ROC) curves, Bland-Altman calibration plots, decision curve analysis and contingency tables. M1-6 were calibrated and outperformed FIGO on true positive rate and positive predictive value. Using LR and MLP, M1, M2 and M4 generated small improvements to the ROC curve and decision curve analysis. M3, M5 and M6 matched FIGO or performed less well. Compared to FIGO, most (excluding LR M4 and MLP M5) had significant discordance in patient classification (McNemar's test P < .05); 55-112 undertreated, 46-206 overtreated. Statistical modelling yielded only small gains over FIGO performance, arising through recategorisation of treatment-resistant patients, with a significant proportion of under/overtreatment as the available data have been used a priori to allocate primary chemotherapy. Streamlining FIGO should now be the focus.  相似文献   
8.
Journal of Immigrant and Minority Health - COVID-19 has disproportionally affected underrepresented minorities (URM) and low-income immigrants in the United States. The aim of the study is to...  相似文献   
9.
10.
In this paper we present a coupled Finite Element Method – Boundary Element Method (FEM-BEM) approach for the solution of the free-boundary axi-symmetric plasma equilibrium problem. The proposed method, obtained from an improvement of the Hagenow-Lackner coupling method, allows to efficiently model the equilibrium problem in unbounded domains by discretizing only the plasma region; the external conductors can be modelled either as 2D or 3D models, according to the problem of interest. The paper explores different iterative methods for the solution of the nonlinear Grad-Shafranov equation, such as Picard, Newton-Raphson and Newton-Krylov, in order to provide a robust and reliable tool, able to handle large-scale problems (e.g. high resolution equilibria). This method has been implemented in the FRIDA code (FRee-boundary Integro-Differential Axisimmetric – https://github. om/matteobonotto/ FRIDA), together with a suitable Adaptive Integration Technique (AIT) for the computation of the source term. FRIDA has been successfully tested and validated against experimental data from RFX-mod device, and numerical equilibria of an ITER-like device.  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