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   759505篇
  免费   54935篇
  国内免费   4789篇
耳鼻咽喉   9699篇
儿科学   23929篇
妇产科学   18055篇
基础医学   116740篇
口腔科学   20798篇
临床医学   70349篇
内科学   143113篇
皮肤病学   16843篇
神经病学   52494篇
特种医学   28250篇
外国民族医学   95篇
外科学   110202篇
综合类   23659篇
现状与发展   16篇
一般理论   167篇
预防医学   54885篇
眼科学   17673篇
药学   59762篇
  54篇
中国医学   5185篇
肿瘤学   47261篇
  2021年   8098篇
  2019年   7186篇
  2018年   9692篇
  2017年   7784篇
  2016年   8628篇
  2015年   10164篇
  2014年   13387篇
  2013年   18466篇
  2012年   24901篇
  2011年   26182篇
  2010年   16115篇
  2009年   14541篇
  2008年   23136篇
  2007年   24625篇
  2006年   24723篇
  2005年   23209篇
  2004年   22005篇
  2003年   21045篇
  2002年   20219篇
  2001年   37602篇
  2000年   37888篇
  1999年   31316篇
  1998年   8444篇
  1997年   7219篇
  1996年   7337篇
  1995年   7056篇
  1994年   6402篇
  1992年   23230篇
  1991年   23108篇
  1990年   22471篇
  1989年   22237篇
  1988年   20147篇
  1987年   19536篇
  1986年   18582篇
  1985年   17365篇
  1984年   12735篇
  1983年   10760篇
  1982年   5944篇
  1979年   11531篇
  1978年   8133篇
  1977年   6839篇
  1976年   6598篇
  1975年   7271篇
  1974年   8498篇
  1973年   8145篇
  1972年   7660篇
  1971年   7128篇
  1970年   6877篇
  1969年   6308篇
  1968年   5781篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Over the years, the number of total hip replacements has been steadily increasing. Despite the improvement in surgical results, the number of claims for malpractice is higher. The primary endpoint of this work is to provide an analysis of litigation after hip replacement, to outline what are the instigating causes and costs. The secondary endpoint is to propose a possible preventive strategy for an improved care and a reduction in legal proceedings. The data of this study were collected from medical and legal files and from professional liability insurance of our institution from January 2005 to December 2016. Out of a total of 4770 THA, 40 claims were received. Peripheral nerve injuries represent the first cause of litigation (37%), followed by infectious complications, leg length discrepancy, metallosis, dislocations of the implant and a case of deep vein thrombosis. From the analysis of the past trial judgment, complications such as nerve lesions and infections are almost always recognized, as a medical error, with a high percentage of claims settled. This study shows the necessity of preventive strategies to reduce the higher number of claims for malpractice in total hip arthroplasty. Some complications such as nerve injuries and infection are frequently considered directly dependent on physician’s errors. Litigations can be reduced providing evidence of a diligent execution of the surgical procedure and of a proper postoperative management: the correct compilation of a specific informed consent and adequate doctor–patient communication.  相似文献   
132.
Marie Warrer Petersen  Tine Sylvest Meyhoff  Marie Helleberg  Maj-Brit Nørregaard Kjær  Anders Granholm  Carl Johan Steensen Hjortsø  Thomas Steen Jensen  Morten Hylander Møller  Peter Buhl Hjortrup  Mik Wetterslev  Gitte Kingo Vesterlund  Lene Russell  Vibeke Lind Jørgensen  Klaus Tjelle  Thomas Benfield  Charlotte Suppli Ulrik  Anne Sofie Andreasen  Thomas Mohr  Morten H. Bestle  Lone Musaeus Poulsen  Mette Friberg Hitz  Thomas Hildebrandt  Lene Surland Knudsen  Anders Møller  Christoffer Grant Sølling  Anne Craveiro Brøchner  Bodil Steen Rasmussen  Henrik Nielsen  Steffen Christensen  Thomas Strøm  Maria Cronhjort  Rebecka Rubenson Wahlin  Stephan Jakob  Luca Cioccari  Balasubramanian Venkatesh  Naomi Hammond  Vivekanand Jha  Sheila Nainan Myatra  Christian Gluud  Theis Lange  Anders Perner 《Acta anaesthesiologica Scandinavica》2020,64(9):1365-1375

Introduction

Severe acute respiratory syndrome coronavirus-2 has caused a pandemic of coronavirus disease (COVID-19) with many patients developing hypoxic respiratory failure. Corticosteroids reduce the time on mechanical ventilation, length of stay in the intensive care unit and potentially also mortality in similar patient populations. However, corticosteroids have undesirable effects, including longer time to viral clearance. Clinical equipoise on the use of corticosteroids for COVID-19 exists.

Methods

The COVID STEROID trial is an international, randomised, stratified, blinded clinical trial. We will allocate 1000 adult patients with COVID-19 receiving ≥10 L/min of oxygen or on mechanical ventilation to intravenous hydrocortisone 200 mg daily vs placebo (0.9% saline) for 7 days. The primary outcome is days alive without life support (ie mechanical ventilation, circulatory support, and renal replacement therapy) at day 28. Secondary outcomes are serious adverse reactions at day 14; days alive without life support at day 90; days alive and out of hospital at day 90; all-cause mortality at day 28, day 90, and 1 year; and health-related quality of life at 1 year. We will conduct the statistical analyses according to this protocol, including interim analyses for every 250 patients followed for 28 days. The primary outcome will be compared using the Kryger Jensen and Lange test in the intention to treat population and reported as differences in means and medians with 95% confidence intervals.

Discussion

The COVID STEROID trial will provide important evidence to guide the use of corticosteroids in COVID-19 and severe hypoxia.
  相似文献   
133.
134.
We consider the scenario where there is an exposure, multiple biologically defined sets of biomarkers, and an outcome. We propose a new two-step procedure that tests if any of the sets of biomarkers mediate the exposure/outcome relationship, while maintaining a prespecified familywise error rate. The first step of the proposed procedure is a screening step that removes all groups that are unlikely to be strongly associated with both the exposure and the outcome. The second step adapts recent advances in postselection inference to test if there are true mediators in each of the remaining candidate sets. We use simulation to show that this simple two-step procedure has higher statistical power to detect true mediating sets when compared with existing procedures. We then use our two-step procedure to identify a set of Lysine-related metabolites that potentially mediate the known relationship between increased body mass index and the increased risk of estrogen-receptor positive breast cancer in postmenopausal women.  相似文献   
135.
136.
137.
Introduction: Cancer treatment is moving away from conventional cytotoxic drugs and towards agents that target specific proteins and mechanisms important to cancer development or survival. The Hedgehog Pathway (HhP) is a signal transduction pathway and its constitutive activation is tumorigenic in basal cell carcinoma (BCC). The HhP enables phenotypic flexibility, and channels tumor-stroma interactions. As a result, it is over-expressed in numerous cancers as well as in the tumor microenvironment and may represent a promising therapeutic target.

Areas covered: In this article, we review the rationale for targeting HhP and its role as an oncogenic driver, in tumor epithelial-to-mesenchymal transition (EMT), and in the tumor microenvironment and describe the results of preclinical and clinical studies involving HhP inhibitors.

Expert opinion: HhP activation plays an important role in both the tumor microenvironment and tumor EMT which can lead to treatment resistance for a number of different malignancies. In addition to standard use in BCC, several HhP inhibitors are in preclinical, early, and mid-stage clinical development for other solid and hematologic malignancies.  相似文献   
138.
139.
The significance of hepatobiliary scintigraphy (HBS) for hepatic graft function assessment was established mostly on retrospective studies and was not widely recognized due to the lack of quantitative data and variation in accuracy. This prospective study was performed to investigate the effectiveness of quantitative HBS for assessing hepatocyte dysfunction and biliary complication in liver transplant recipients.In 57 recipients who had undergone orthotopic liver transplantation, a total of 67 dynamic 99mTc-EHIDA scans were performed and quantitative parameters including the hepatocyte extraction fraction (HEF), time to maximum hepatic radioactivity (Tmax), and time for peak activity to decrease by 50% (T1/2) were calculated. The scintigraphic results based on the 3 parameters were compared against the final diagnosis. A ROC curve analysis was carried out to identify the cutoff value of Tmax for diagnosis of biliary stricture. Correlation between the parameters of postoperative HBS and conventional biochemical liver function indices were also analyzed.Quantitative 99mTc-EHIDA HBS had an overall sensitivity of 94.12% (16/17), specificity of 93.33% (42/45), and diagnostic accuracy of 93.55% (58/62) for detecting hepatocyte dysfunction and biliary complication in liver transplant recipients. The recommended cutoff value of Tmax for diagnosis of post-transplant biliary stricture was set at 15.75 min with a sensitivity of 100.0% and a specificity of 94.0%. The scintigraphic parameters (HEF, Tmax) were statistically significantly associated with the conventional liver function parameters.Quantitative 99mTc-EHIDA HBS offers a noninvasive imaging modality with high sensitivity and specificity to diagnose hepatocyte dysfunction as well as distinguish between patients with or without biliary stricture following liver transplantation. Furthermore, HEF and Tmax values obtained from dynamic HBS show good correlation with conventional liver function parameters.  相似文献   
140.
Osteoporosis is a condition in which the bones are thinner and more liable to fracture. It is commoner in women and in people over 50. It cannot be cured so the focus is on prevention, which means identifying and addressing risk factors such as obesity, low vitamin D, chronic inflammation and prolonged steroid medication. Chronic urticaria (hives, CU) is an inflammatory condition, so one might expect it to be linked with osteoporosis, but that has never been investigated. If people with CU are indeed more likely to develop osteoporosis, they could be advised about preventative measures. To study this, doctors from Israel identified 11,944 patients diagnosed with CU in a large medical database covering 4.5 million people. A potential difficulty was that people with CU are more likely to be female, obese and to have been treated with systemic steroids, all of which also increase the risk of osteoporosis. Therefore for each CU patient they studied 5 age- and sex-matched control patients (people of the same age and sex but without CU) and their analyses took into account other known risk factors for osteoporosis. During a 16 year period 8.7% of the patients with CU were diagnosed with osteoporosis compared with 6.8% of the controls. They concluded that CU is a small but significant additional risk factor for osteoporosis. An accompanying editorial cautions against basing conclusions on routine health records which may not have all the information required. Nonetheless, doctors treating chronic urticaria might bear in mind the risk of osteoporosis in their patients, and counsel accordingly.  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