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   2789篇
  免费   132篇
  国内免费   16篇
耳鼻咽喉   126篇
儿科学   40篇
妇产科学   52篇
基础医学   440篇
口腔科学   79篇
临床医学   186篇
内科学   651篇
皮肤病学   19篇
神经病学   218篇
特种医学   104篇
外科学   370篇
综合类   13篇
预防医学   82篇
眼科学   24篇
药学   192篇
中国医学   13篇
肿瘤学   328篇
  2023年   19篇
  2022年   35篇
  2021年   59篇
  2020年   38篇
  2019年   55篇
  2018年   62篇
  2017年   59篇
  2016年   48篇
  2015年   56篇
  2014年   80篇
  2013年   91篇
  2012年   153篇
  2011年   191篇
  2010年   78篇
  2009年   96篇
  2008年   169篇
  2007年   193篇
  2006年   215篇
  2005年   233篇
  2004年   197篇
  2003年   185篇
  2002年   175篇
  2001年   32篇
  2000年   21篇
  1999年   39篇
  1998年   35篇
  1997年   30篇
  1996年   38篇
  1995年   24篇
  1994年   21篇
  1993年   23篇
  1992年   13篇
  1991年   12篇
  1990年   16篇
  1989年   14篇
  1988年   10篇
  1987年   8篇
  1986年   8篇
  1985年   11篇
  1984年   14篇
  1983年   9篇
  1982年   5篇
  1981年   6篇
  1980年   11篇
  1979年   8篇
  1978年   8篇
  1977年   5篇
  1976年   5篇
  1974年   3篇
  1967年   3篇
排序方式: 共有2937条查询结果,搜索用时 15 毫秒
51.
In September 2003, a double-balloon endoscope (DBE) composed of balloons attached to a scope and an overtube was released in Japan prior to becoming available in other parts of the world. The DBE was developed by Dr. Yamamoto (1), and 5 different types of scopes with different uses have already been marketed. In April 2007, a single-balloon small intestinal endoscope was released with a balloon attached only to the overtube as a subsequent model. This article presents a detailed account of the development of these scopes up to the present time.  相似文献   
52.
53.
Summary A modified version of Brockenbrough's trans-septal catheterization technique was carried out in 11 patients indicated for percutaneous transvenous mitral commissurotomy (PTMC). In 8/11 (72.7%), a coiled guide-wire was successfully inserted through theforamen ovale without atrial septal puncture. The Brockenbrough needle was used merely to maintain stiffness and the orientation of the dilator. PTMC was performed with an Inoue single balloon without incident.Patent foramen ovale was found by transesophageal echocardiography prior to the operation in only 1/11 patients (9.0%); nonetheless, it proved not to be a critical factor for the success of the procedure. This procedure seems to have much potential to enable the treatment of mitral stenosis with a lowered risk to the patient, as long as it is performed with precision and caution.  相似文献   
54.
Aim: A low platelet count leads to dose reduction of interferon (IFN) and is associated with failure to achieve a sustained virological response (SVR) in chronic hepatitis C patients. However, partial splenic embolization (PSE) is effective for treating thrombocytopenia resulting from hypersplenism. Methods: We compared the clinical features of 10 patients receiving PSE prior to the combination therapy of IFN and ribavirin (RBV) (PSE group) with those of 10 non‐receiving PSE patients (non‐PSE group). Results: In all 10 patients, PSE was successfully performed without serious adverse events. After PSE, leukocyte, neutrophil, and platelet counts significantly increased. The period from PSE to the initiation of the combination therapy was 15 (7–21) days. In the PSE group, two of six patients (33%) infected with genotype 1, and all four patients infected with genotype 2, achieved SVR. In the non‐PSE group, only three patients infected with genotype 2 achieved SVR. Two patients in the PSE group and one in the non‐PSE group discontinued the combination therapy. Three patients of the PSE group and five of the non‐PSE group reduced the dose of pegylated IFN‐α‐2b because of thrombocytopenia. In the PSE group, platelet counts during the combination therapy fell to baseline levels; however, they did not fall to lower levels than baseline levels. In the non‐PSE group, platelet counts 1 month after the initiation of the therapy were lower than baseline levels. Conclusion: The increase of platelet counts after PSE may allow the safe use of IFN and RBV and improve the SVR rate in chronic hepatitis C patients with thrombocytopenia.  相似文献   
55.
Acaryochloris marina is a unique cyanobacterium that is able to produce chlorophyll d as its primary photosynthetic pigment and thus efficiently use far-red light for photosynthesis. Acaryochloris species have been isolated from marine environments in association with other oxygenic phototrophs, which may have driven the niche-filling introduction of chlorophyll d. To investigate these unique adaptations, we have sequenced the complete genome of A. marina. The DNA content of A. marina is composed of 8.3 million base pairs, which is among the largest bacterial genomes sequenced thus far. This large array of genomic data is distributed into nine single-copy plasmids that code for >25% of the putative ORFs. Heavy duplication of genes related to DNA repair and recombination (primarily recA) and transposable elements could account for genetic mobility and genome expansion. We discuss points of interest for the biosynthesis of the unusual pigments chlorophyll d and α-carotene and genes responsible for previously studied phycobilin aggregates. Our analysis also reveals that A. marina carries a unique complement of genes for these phycobiliproteins in relation to those coding for antenna proteins related to those in Prochlorococcus species. The global replacement of major photosynthetic pigments appears to have incurred only minimal specializations in reaction center proteins to accommodate these alternate pigments. These features clearly show that the genus Acaryochloris is a fitting candidate for understanding genome expansion, gene acquisition, ecological adaptation, and photosystem modification in the cyanobacteria.  相似文献   
56.
57.
Hyaluronidase is one of the most important enzymes in the development of many diseases. In this study, a series of xyloside analogues bearing a triazole and tetrazole at the anomeric position were prepared from xylosylthioureas and evaluated their inhibitory effects on the hyaluronidase. Triazole and tetrazole skeletons were formed via the Hg(OAc)2-mediated desulfurizative cyclization through carbodiimide intermediates. According to in vitro anti-hyaluronidase assay, tetrazole-xylosides having p-chloro- or p-nitro-substitution exhibited the high inhibition rates, whereas the compound having p-trifluoromethyl group on the structure did not show the potency. Our results demonstrated the importance of tetrazole-xylosides as hyaluronidase inhibitors.  相似文献   
58.
Journal of Thrombosis and Thrombolysis - Prolonged anticoagulation therapy is recommended for patients with intermediate-risk for recurrence of venous thromboembolism (VTE). The current study aimed...  相似文献   
59.
60.
INTRODUCTION: The aim of this study was to examine the electrophysiologic characteristics of the normal left interventricular septum (LIVS). METHODS AND RESULTS: We explored the LIVS in search of endocardial potentials following ventricular electrograms during sinus rhythm in 28 patients without structural heart disease. In all patients, low-frequency (mean amplitude: 0.81 +/- 0.33 mV) systolic potentials (LA1) were detected in a basal-to-apical activation sequence (earliest to latest QRS-LA1 interval: 93.3 +/- 10.8 ms to 127.1 +/- 16.6 ms). Programmed stimulation demonstrated decremental conduction properties, and the effective refractory period of the tissue between the ventricular electrogram and LA1 at baseline (376.7 +/- 48.8 ms) was significantly prolonged by disopyramide (421.3 +/- 54.1 ms, P < 0.05 vs baseline). In 21 patients (75%), diastolic potentials (LA2) morphologically similar to LA1 (mean amplitude: 0.52 +/- 0.17 mV) were detected in an apical-to-basal activation sequence (earliest to latest QRS-LA2 interval: 368.9 +/- 32.4 ms to 440.7 +/- 45.8 ms). Para-Hisian pacing with capture of the His bundle showed shorter S-LA1 and S-LA2 intervals compared to the beats without His-bundle capture but with ventricular capture (156.3 +/- 11.2 ms vs 183.2 +/- 12.3 ms, and 385.7 +/- 21.6 ms vs 397.4 +/- 23.4 ms, respectively, P < 0.0001). At the same rate, the LA1-LA2 interval was significantly shorter during right ventricular apical than atrial overdrive pacing (220.4 +/- 23.1 ms vs 261.4 +/- 30.7 ms, P < 0.0001). CONCLUSION: Unique myocardial bundles with slow conduction properties and various electrical connections with the specialized conduction system may exist in the LIVS of normal human hearts.  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