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   8014篇
  免费   719篇
  国内免费   37篇
耳鼻咽喉   57篇
儿科学   261篇
妇产科学   115篇
基础医学   1228篇
口腔科学   291篇
临床医学   943篇
内科学   1426篇
皮肤病学   320篇
神经病学   837篇
特种医学   578篇
外科学   1112篇
综合类   149篇
一般理论   4篇
预防医学   630篇
眼科学   69篇
药学   478篇
中国医学   3篇
肿瘤学   269篇
  2021年   77篇
  2019年   76篇
  2018年   112篇
  2017年   86篇
  2016年   96篇
  2015年   113篇
  2014年   150篇
  2013年   268篇
  2012年   264篇
  2011年   267篇
  2010年   191篇
  2009年   187篇
  2008年   264篇
  2007年   265篇
  2006年   304篇
  2005年   275篇
  2004年   284篇
  2003年   270篇
  2002年   254篇
  2001年   276篇
  2000年   262篇
  1999年   240篇
  1998年   164篇
  1997年   153篇
  1996年   181篇
  1995年   141篇
  1994年   148篇
  1993年   137篇
  1992年   182篇
  1991年   185篇
  1990年   178篇
  1989年   194篇
  1988年   168篇
  1987年   160篇
  1986年   134篇
  1985年   124篇
  1984年   134篇
  1982年   78篇
  1981年   73篇
  1980年   91篇
  1979年   81篇
  1978年   79篇
  1977年   86篇
  1976年   93篇
  1975年   103篇
  1974年   67篇
  1972年   83篇
  1971年   69篇
  1965年   60篇
  1960年   68篇
排序方式: 共有8770条查询结果,搜索用时 15 毫秒
1.
Fibroblast growth factor receptors (FGFRs) are aberrantly activated through single-nucleotide variants, gene fusions and copy number amplifications in 5–10% of all human cancers, although this frequency increases to 10–30% in urothelial carcinoma and intrahepatic cholangiocarcinoma. We begin this review by highlighting the diversity of FGFR genomic alterations identified in human cancers and the current challenges associated with the development of clinical-grade molecular diagnostic tests to accurately detect these alterations in the tissue and blood of patients. The past decade has seen significant advancements in the development of FGFR-targeted therapies, which include selective, non-selective and covalent small-molecule inhibitors, as well as monoclonal antibodies against the receptors. We describe the expanding landscape of anti-FGFR therapies that are being assessed in early phase and randomised controlled clinical trials, such as erdafitinib and pemigatinib, which are approved by the Food and Drug Administration for the treatment of FGFR3-mutated urothelial carcinoma and FGFR2-fusion cholangiocarcinoma, respectively. However, despite initial sensitivity to FGFR inhibition, acquired drug resistance leading to cancer progression develops in most patients. This phenomenon underscores the need to clearly delineate tumour-intrinsic and tumour-extrinsic mechanisms of resistance to facilitate the development of second-generation FGFR inhibitors and novel treatment strategies beyond progression on targeted therapy.Subject terms: Cancer, Cancer  相似文献   
2.
3.
4.
MATTHEW  B.  COLLIER  C.  ANDERSON  ENGH  JR.  JAMES  P.  MCAULEY  STUART  D.  GINN  GERARD  A.  ENGH  蔡迅梓 《骨科动态》2006,2(2):93-99
背景:从关节和胫骨假体聚乙烯衬垫后表面转移磨损碎屑,是全膝关节置换术后假体周围骨溶解的主要原因。全膝人工关节假体设计随时问而发生变化,例如对胫骨盘近端表面的粗糙度和聚乙烯衬垫的灭菌方法。我们假设胫骨盘表面抛光和采用空气中γ射线照射之外的其他方法对衬垫灭菌,可降低骨溶解的发生率。方法:从1987年至1998年,我们采用后十字韧带保留型的解剖型组配式全膝人工关节假体系列。对300名患者施行365例全膝关节置换术。术后5至10年,对这些患者的膝关节摄正、侧位X线片。由两位关节置换专家对X线片上的骨溶解状况进行单独评定(骨溶解的界定标准为假体周围存在边缘清晰的非线性松质骨丢失区)。结果:在粗糙表面的胫骨盘的242例膝关节中,使用空气中γ射线照射灭菌的衬垫固定,有34%(82例)骨溶解阳性。用惰性气体中γ射线照射或没有照射的衬垫与抛光表面连接的98例膝关节中,有9%(9例)骨溶解阳性。骨溶解与六项因素相关,这些因素为:一项与患者(男性)相关、一项与胫骨盘(近端表面抛光)相关、三项与聚乙烯衬垫(加工的原材料、灭菌方法及存放时间)相关及一项与手术技术(股骨假体与胫骨假体间的过伸)相关。结论:在这类假体设计中,胫骨盘近端表面采用抛光及衬垫采用更为先进的灭菌方法(不用空气中γ射线照射灭菌)能显著减少骨溶解的发生率,但不能避免骨溶解。  相似文献   
5.
Maternal and Child Health Journal -  相似文献   
6.
Since its introduction in early 1985, the Volk +90D lens has become a very popular auxiliary lens for biomicroscopic fundus evaluation. The Volk +90D lens provides a wide field of view which is accessible by simple scanning of the biomicroscope. The necessity to hand hold the lens, however, has not always provided enough stability, particularly for the novice user. This article describes a newly introduced holder for the Volk +90D lens which mounts on the base of the biomicroscope headrest providing rapid and stable lens placement. Use of this holder improves the technique of retinal examination and photography by stabilizing the image and by freeing both hands to operate the slit lamp biomicroscope. The enhanced stability afforded by this holder also gives the examiner the practical capability of viewing the posterior pole without mydriasis.  相似文献   
7.
The precision of positron emission tomography: theory and measurement   总被引:1,自引:0,他引:1  
The limits of quantitation with positron emission tomography (PET) are examined with respect to the noise propagation resulting from radioactive decay and other sources of random error. Theoretical methods for evaluating the statistical error have been devised but seldom applied to experimental data obtained on human subjects. This paper extends the analysis in several ways: (1) A Monte Carlo method is described for tracking the propagation of statistical error through the analysis of in vivo measurements; (2) Experimental data, obtained in phantoms, validating the Monte Carlo method and other methods are presented; (3) A difference in activation paradigm, performed on regional CBF (rCBF) data from five human subjects, was analyzed on 1.6-cm diameter regions of interest to determine the mean fractional statistical error in PET tissue concentration and in rCBF before and after stereotactic transformation; and (4) A linear statistical model and calculations of the various statistical errors were used to estimate the magnitude of the subject-specific fluctuations under various conditions. In this specific example, the root mean squared (RMS) noise in flow measurements was about three times higher than the RMS noise in the concentration measurements. In addition, the total random error was almost equally partitioned between statistical error and random fluctuations due to all other sources.  相似文献   
8.
Haaga  JR; Beale  SM 《Radiology》1986,161(3):829-830
By injecting small amounts of CO2 through a needle, one can move bowel or bladder from the intended path of instruments during interventional procedures. The technique worked well in six of seven cases in the pelvis and retroperitoneum; it was not effective in the mediastinum or midabdomen (n = 6).  相似文献   
9.
Coagulation screening before epidural analgesia in pre-eclampsia   总被引:1,自引:0,他引:1  
A questionnaire survey of current practice at a small cross-section of obstetric units, covering 22% of all United Kingdom deliveries, revealed a marked lack of standard practice regarding requests for coagulation screens on pre-eclamptic patients who require epidural procedures. A retrospective audit was therefore carried out on 434 coagulation screens requested for pre-eclamptic patients in whom epidural analgesia might have been considered. Borderline abnormalities of coagulation were found in only 10 patients (2%). Platelet counts of less than 150 x 10(9)/litre were present in 28% of cases. 'Significant' thrombocytopenia (less than 100 x 10(9)/litre) and all coagulation abnormalities were only encountered in severe pre-eclampsia (diastolic blood pressure of greater than 110 mmHg and proteinuria of + + or greater). Furthermore, coagulation abnormality was always associated with a reduced platelet count (mean, 97 x 10(9)/litre). This study would therefore support anaesthetic practice which restricted any requests for coagulation testing to severe pre-eclamptic patients only. For these patients first line testing could be limited to a platelet count.  相似文献   
10.
Primary tuberculous pathology in nasolpolypi is a rare condition. A case of bilateral ethmoidal polypi with tubercular lesion diagnosed on histopathologlcal examination is being reported and the available relevant literature has been reviewed.  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