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   1641341篇
  免费   124801篇
  国内免费   3889篇
耳鼻咽喉   23620篇
儿科学   50217篇
妇产科学   47920篇
基础医学   234091篇
口腔科学   47354篇
临床医学   140273篇
内科学   322762篇
皮肤病学   34051篇
神经病学   132172篇
特种医学   66505篇
外国民族医学   492篇
外科学   258060篇
综合类   40381篇
现状与发展   2篇
一般理论   494篇
预防医学   123480篇
眼科学   38266篇
药学   120102篇
中国医学   3174篇
肿瘤学   86615篇
  2018年   15372篇
  2015年   15419篇
  2014年   22099篇
  2013年   34009篇
  2012年   45405篇
  2011年   48116篇
  2010年   28694篇
  2009年   27209篇
  2008年   45845篇
  2007年   49353篇
  2006年   49287篇
  2005年   48571篇
  2004年   47022篇
  2003年   45505篇
  2002年   44197篇
  2001年   71122篇
  2000年   72902篇
  1999年   62038篇
  1998年   18011篇
  1997年   16509篇
  1996年   16253篇
  1995年   15315篇
  1994年   14654篇
  1993年   13748篇
  1992年   50609篇
  1991年   48999篇
  1990年   48029篇
  1989年   46295篇
  1988年   43225篇
  1987年   42569篇
  1986年   40717篇
  1985年   39069篇
  1984年   29791篇
  1983年   25430篇
  1982年   15773篇
  1981年   14208篇
  1980年   13444篇
  1979年   29066篇
  1978年   20730篇
  1977年   17473篇
  1976年   16322篇
  1975年   17771篇
  1974年   21727篇
  1973年   20788篇
  1972年   19760篇
  1971年   18274篇
  1970年   17522篇
  1969年   16694篇
  1968年   15497篇
  1967年   14269篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Cognitive Therapy and Research - Despite interest in psychological inflexibility as a marker of suicide risk, no measure of psychological inflexibility specific to SI exists. The present study...  相似文献   
13.
14.
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   
15.
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   
16.
17.
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   
18.
19.
20.
Cutaneous leiomyomas are rare benign smooth‐muscle tumors. These lesions are distinguished based on their cell of origin and are subclassified as pilar leiomyoma, angioleiomyoma, and genital‐type leiomyoma. Nipple leiomyoma is the least common genital‐type leiomyoma, arising from the dartoic muscle cell of the nipple. Histologic examination of the lesion is necessary for definitive diagnosis, and these uncommon tumors can pose a diagnostic challenge. We describe herein a series of six nipple leiomyomas with a spectrum of histologic appearances.  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