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   6750篇
  免费   350篇
  国内免费   32篇
耳鼻咽喉   50篇
儿科学   110篇
妇产科学   116篇
基础医学   966篇
口腔科学   103篇
临床医学   609篇
内科学   1180篇
皮肤病学   351篇
神经病学   755篇
特种医学   359篇
外科学   903篇
综合类   54篇
预防医学   326篇
眼科学   120篇
药学   510篇
中国医学   29篇
肿瘤学   591篇
  2023年   38篇
  2022年   74篇
  2021年   120篇
  2020年   83篇
  2019年   97篇
  2018年   133篇
  2017年   130篇
  2016年   159篇
  2015年   208篇
  2014年   239篇
  2013年   278篇
  2012年   444篇
  2011年   440篇
  2010年   306篇
  2009年   283篇
  2008年   471篇
  2007年   494篇
  2006年   491篇
  2005年   475篇
  2004年   418篇
  2003年   426篇
  2002年   431篇
  2001年   89篇
  2000年   59篇
  1999年   92篇
  1998年   102篇
  1997年   78篇
  1996年   66篇
  1995年   41篇
  1994年   48篇
  1993年   41篇
  1992年   30篇
  1991年   11篇
  1990年   17篇
  1989年   18篇
  1988年   14篇
  1987年   11篇
  1986年   12篇
  1985年   9篇
  1984年   9篇
  1983年   8篇
  1982年   10篇
  1981年   10篇
  1980年   19篇
  1979年   7篇
  1978年   13篇
  1977年   10篇
  1976年   11篇
  1975年   7篇
  1973年   7篇
排序方式: 共有7132条查询结果,搜索用时 15 毫秒
21.
22.
Synthesis and characterization of methacrylate-monofunctionalized crown ether compounds based on derivatives of 2-hydroxymethyl-1,4,7,10,13-pentaoxacyclopentadecane and 4′-hydroxymethyl-1,4,7,10,13-pentaoxabenzocyclopentadecane is described. By differential scanning calorimetry (DSC) and thermooptical analysis (TOA) it is shown that the synthesized compounds and their sodium triflate complexes exhibit columnar mesophases.  相似文献   
23.
Summary The purpose of our study was to check whether the dosage recommended for the low molecular weight heparin tested here, i.e., 50% of the corresponding unfractionated heparin dose, is adequate to prevent clot formation in the extracorporeal system. Sixteen dialysis treatments of 4–5 h were given to each of six chronic dialysis patients. In dialyses 1, 2, 15 and 16 unfractionated heparin (initial dose 35 IU/kg, continuous dose 20 IU/kg/h) was given, and in dialyses 3–14 low molecular weight heparin (initial dose 17.5 anti-Xa U/kg, continuous dose 10 anti-X U/kg/h). At these dose levels of low molecular weight heparin, clot formation occurred in the extracorporeal system in five of the six patients, despite the fact that the plasma anti-Xa level of 0.5 U/ml recommended by the manufacturer had been attained. For this reason the continuous dose of low molecular weight heparin had to be raised to approx. 80% of the corresponding continuous dose of unfractionated heparin. A plasma anti-Xa level of 0.7 U/ml is necessary to prevent extracorporeal clot formation.Abbreviations anti-Xa U Anti-factor Xa unit - aPTT Activated partial thromboplastin time - AT III Antithrombin III - IU International unit - LMWH Low molecular weight heparin - UFH Unfractionated heparin  相似文献   
24.
25.
Brütsch  René  Zahn  Ralf  Zeymer  Uwe 《Notfall & Rettungsmedizin》2021,24(7):1055-1062
Notfall + Rettungsmedizin - Das akute Koronarsyndrom ist der häufigste Grund für einen Rettungsdiensteinsatz in Deutschland. So resultieren in etwa 20–25 % aller Einsätze...  相似文献   
26.
Hirayama’s disease is a benign juvenile form of focal amyotrophy affecting the upper limbs. Previous studies have suggested that the disorder is a neck flexion induced cervical myelopathy. We report clinical and magnetic resonance imaging findings in nine patients with Hirayama’s disease. Cervical imaging of seven patients revealed spinal cord changes consisting of focal atrophy and foci of signal alterations. On neck flexion a forward movement and mild reduction in the anteroposterior diameter of the lower cervical cord against the vertebral bodies was noted in affected individuals as well as in five normal controls. In contrast to earlier reports, none of our patients showed complete obliteration of the posterior subarachnoid space. Measurement of the anteroposterior spinal cord diameter in each vertebral segment (C4–C7) revealed no significant differences in the degree of spinal cord flattening between the two groups. Furthermore, two of our patients had significant degenerative changes in the cervical spine (disc herniation, retrospondylosis) contralateral to the clinically affected side. These degenerative changes resulted in a marked cord compression on neck flexion but were not associated with ipsilateral clinical abnormalities or spinal cord alterations. Our results argue against a flexion-induced cervical myelopathy and support the view that Hirayama’s disease is an intrinsic motor neuron disease. Received: 15 March 1999 Received in revised form: 25 May 1999 Accepted: 1 June 1999  相似文献   
27.
Is cytokine removal by continuous hemofiltration feasible?   总被引:19,自引:0,他引:19  
Patients who are critically ill with acute renal failure and sepsis have extremely high mortality rates. While it seems reasonable that eliminating the inflammatory mediators (such as cytokines, chemokines, tumor necrosis factor-alpha, etc.) by continuous renal replacement therapy (CRRT) would be effective, studies show that only insubstantial numbers of these mediators are removed in comparison with endogenous clearance. Mass removal seems only to be effective when highly permeable membranes (sieving coefficient of approximately 1.0) are used, there is a filtrate volume greater than 2 liters/hour, and when the half-life of the substance to be eliminated is greater than 60 minutes. Removal of cytokines by membrane adsorption is another possibility. However, because the membrane surfaces are saturated after a few hours, frequent filter changes are necessary for them to generate effective adsorption of these mediators. Despite filter changes, only a brief and transient drop in the TNF plasma level has been observed. Controlled clinical trials are needed to determine whether or not CRRT actually has a beneficial effect on the systemic inflammatory response syndrome (SIRS).  相似文献   
28.
Important inroads are being made into understanding the pathophysiology of diarrhea. Clear understanding of key mechanisms should suggest new approaches to combat disease. Exciting developments are occurring in terms of super-ORS solutions, particularly with the promise of short chained glucose polymers and glutamine. Perhaps the most important development is the prospect of a good rotavirus vaccine being available before the end of the decade. Chronic diarrhea seems to be on the increase globally, probably because of the success of ORS. The mechanisms that lead to mucosal injury are elusive, and therapy still largely supportive and empiric. Celiac disease continues to be a puzzle, because of the uncomfortable feeling that a majority of cases may be missed because of atypical presentations. The successful use of long term parenteral nutrition has allowed survival and better charaterization of cases that otherwise would have perished as ‘lethal protracted diarrhea’. Microvillus inclusion disease may be the commonest congenital secretory diarrhea. The role of the recently reported high prevalence of glucoamlase deficiency may be important. Lastly, attention to micronutrients, particularly low vitamin A and probably zinc may prove to be important in prevention and amelioration of diarrhea and growth failure.  相似文献   
29.
Summary The Vigilance Scale (VS) is a 12-step additive scale (Guttman scale) that allows assessment of the behavioral deficit in the unconscious state and the state of clouding of consciousness. Despite restrictions on its applicability, which are discussed in detail, the VS seems to be a useful measuring device that indicates the level of brain function a patient with a disturbance of consciousness can actually attain. There are two categories of scale errors to be found, the first being caused by various instrumental disorders, i.e., severe motor deficits, the second resulting from the probabilistic approach of the VS to a Guttman scale.  相似文献   
30.
PURPOSE: A Phase I/IIb multicenter study was conducted to evaluate the safety and immunogenicity of the anti-idiotypic antibody vaccine ACA125 that functionally imitates the tumor antigen CA125 in 119 patients with advanced ovarian carcinoma. A preliminary report on the initial 42 patients demonstrated safety and immunogenicity. EXPERIMENTAL DESIGN: Using the complete intention-to-treat population (n = 119) who received a mean of 9.7 ACA125 applications, survival was analyzed with respect to immunological responses. RESULTS: In 81 patients (68.1%), a specific anti-anti-idiotypic antibody (Ab3) response could be induced. Additionally, the development of CA125-specific antibodies (Ab1') and antibody-dependent cell-mediated cytotoxicity of CA125-positive tumor cells was observed in 50.4% and 26.9% of patients, respectively. The median survival of all patients was 19.4 months (range, 0.5-56.1 months). Ab3-positive patients showed a significantly longer survival (median, 23.4 months; P < 0.0001) as compared with Ab3-negative patients (median, 4.9 months). A positive Ab3 response remained associated with longer survival when controlling for other prognostic factors including FIGO (International Federation of Gynecologists and Obstetricians) stage, response to and type of first-line chemotherapy, number of previous treatments, or concomitant antitumor therapy. With regard to safety, repeated vaccination was well tolerated. No serious adverse events related to the application of ACA125 occurred. CONCLUSIONS: Although the uncontrolled design of this study prevents definitive conclusions with respect to subgroups, the data support a relationship between Ab3 response and survival time. Thus, the need for further randomized, controlled clinical trials to establish efficacy of the vaccine ACA125 seems to be indicated.  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