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   3360篇
  免费   131篇
  国内免费   1篇
耳鼻咽喉   103篇
儿科学   164篇
妇产科学   123篇
基础医学   543篇
口腔科学   57篇
临床医学   248篇
内科学   548篇
皮肤病学   222篇
神经病学   193篇
特种医学   158篇
外科学   642篇
综合类   15篇
一般理论   6篇
预防医学   99篇
眼科学   37篇
药学   209篇
中国医学   1篇
肿瘤学   124篇
  2021年   37篇
  2019年   31篇
  2018年   44篇
  2017年   27篇
  2016年   46篇
  2015年   54篇
  2014年   56篇
  2013年   112篇
  2012年   140篇
  2011年   147篇
  2010年   83篇
  2009年   86篇
  2008年   117篇
  2007年   128篇
  2006年   116篇
  2005年   153篇
  2004年   125篇
  2003年   112篇
  2002年   112篇
  2001年   74篇
  2000年   93篇
  1999年   66篇
  1998年   24篇
  1997年   21篇
  1996年   22篇
  1992年   38篇
  1991年   46篇
  1990年   52篇
  1989年   38篇
  1988年   34篇
  1987年   38篇
  1986年   37篇
  1985年   31篇
  1984年   29篇
  1979年   19篇
  1973年   23篇
  1971年   27篇
  1939年   23篇
  1934年   20篇
  1933年   34篇
  1932年   30篇
  1931年   20篇
  1930年   21篇
  1925年   21篇
  1924年   19篇
  1923年   19篇
  1922年   21篇
  1913年   39篇
  1912年   22篇
  1903年   23篇
排序方式: 共有3492条查询结果,搜索用时 15 毫秒
1.
Zusammenfassung Die von uns angegebene Flockungsprobe im Serum mit Hayemscher Lösung zur Diagnose der atrophischen Lebercirrhose und zur einfachen Erkennung der meisten Takata-positiven und Takata-negativen Seren eignet sich auch zur Untersuchung von Ascites bezüglich seiner Genese. Auf Zusatz von Hayemscher Lösung zeigt der Ascites bei Lebercirrhose ein wesentlich anderes Verhalten als der Ascites bei Carcinom, Nephrose oder Herzinsuffizienz. Die einfache und rasch ausführbare Untersuchung des frischen Ascites mit Hayemscher Losung gestattet daher einen Ascites bei Lebercirrhose von solchen anderer Genese in kurzer Zeit zu differenzieren.  相似文献   
2.
3.
4.
A group of 159 patients previously reported as having margins positive for disease after radical prostatectomy with or without adjunctive postoperative radiation was reanalyzed to determine whether the reported benefit did indeed exist. Upon re-examination of the 159 patients 15 were identified who did not receive radical prostatectomy but who were analyzed as if they had received this therapy. An updated review of the total pool of 159 patients with analysis as to failure, death of any cause or death of prostatic cancer demonstrated no benefit of postoperative radiation therapy for margin positive disease. Exclusion of patients who did not receive radical prostatectomy and analysis as described also failed to identify any benefit of postoperative adjunctive radiation therapy.  相似文献   
5.
Objective: The aim of the study was to investigate whether or not esuprone binds substantially to MAO-A in the human brain. Methods: In a randomised double-blind placebo-controlled study 16 male healthy volunteers were examined␣with positron emission tomography (PET) with [11C]harmine. Eight of the volunteers were given daily doses of 800 mg esuprone, four were given bi-daily doses of 300 mg moclobemide, and four volunteers were given placebo tablets. PET was performed before initiation of a 7-day treatment period. On day 7, one investigation was made immediately before administration of the drug, representing 23 h after the previous day's treatment for esuprone and 11 h after the last tablets of moclobemide. Further investigations were made 4 h and 8 h after the morning dose on day 7. Results: PET showed a high degree of binding of [11C]harmine, a high-affinity ligand for MAO-A, before the start of treatment, and a marked and similar reduction after treatment with esuprone and moclobemide. A slight tendency for normalisation of enzyme binding was observed at the last time point. In the placebo group no change was observed. Plasma kinetics of esuprone showed a rapid elimination with a half-life of about 4 h. Conclusion: The study demonstrates that esuprone was comparable to moclobemide in its effect on MAO-A inhibition in the brain at the doses given. This is an illustration of the potential of PET to monitor drug effects directly on target biochemical systems in the brain in human volunteers, and the possibility of using these data, rather than pharmacokinetic data, for the determination of dosing intervals. Received: 21 August 1996 / Accepted in revised form: 22 November 1996  相似文献   
6.
PURPOSE: This paper briefly summarizes the research on increased radiosensitivity in breast cancer patients measured by the micronucleus test (MNT) and its association to genetic variants in DNA repair genes. More preliminary data are presented on the distribution of chromosomes and chromosome fragments in micronuclei (MN) in order to gain more information on clastogenic and aneugenic effects and better understand the phenotype of increased radiosensitivity. MATERIAL AND METHODS: Reports of relevant studies obtained from a search of PubMed and studies referenced in those reports were reviewed. In four patients with high MN frequency (three cancer patients, one control) and four probands with low MN frequency, the presence of chromosome fragments or whole chromosomes in MN was determined by fluorescence in situ hybridization analysis for chromosomes 1, 7, and 17. RESULTS: An increased MN frequency in breast cancer patients compared to controls has consistently been reported with high significance. Higher MN frequencies were observed in 20-50% of breast cancer patients. Chromosomal fragments of chromosome 17, but not of chromosomes 1 and 7 were more frequent in the probands with high MN frequency than in those with low frequency (p = 0.045). CONCLUSION: The MNT detects a cellular phenotype common to a portion of sporadic breast cancer patients. This phenotype is very likely to be genetically determined. For the genetic dissection of breast cancer susceptibility this phenotype may turn out to be more efficient than breast cancer itself. Additional parameters which can be measured simultaneously with the MN frequency may be able to further enhance its usefulness.  相似文献   
7.
OBJECTIVE: Recent studies have demonstrated that transplanted bone marrow-derived stem cells (BMCs) possess a broad differentiation potential and are able to form new cardiomyocytes. However, the identity of BMCs as true cardiomyocytes is still ambiguous. Therefore, we investigated the fate of transplanted fluorescence labeled BMCs and cardiomyocytes in co-culture. METHODS: For cell tracking we used two different fluorescent probes, Vybrant/DiO and Vybrant/DiI. BMCs were taken from human sternal marrow, purified using a Ficoll-gradient-centrifugation, treated with 5-azacytidine and stained with Vybrant/DiO. Furthermore, isolated spontaneous beating cardiomyocytes of neonatal rats (CM) were labeled with Vybrant/DiI. Thereafter, the BMCs were transplanted into CM-cultures and investigated on day 1, 4, 7, 14 and 28 using two-color fluorescence phenotyping by laser-scanning-cytometry (LSC). Two-color positive cells were harvested by patch-clamp technique and beta-MHC mRNA expression was analyzed by single-cell PCR. RESULTS: Two different morphological phenotypes were observed by LSC. First, isolated DiO labeled BMCs without contact or with direct cell contact to DiI labeled CMs. Second, some BMCs and CMs were double positive for DiO/DiI spontaneously forming hybrids. This population increased by 18% from day 1 to 4 and decreased only slightly until day 28. Additionally, few two-color positive cell formations expressed both human and rat specific beta-MHC mRNA as well as only human beta-MHC mRNA indicating that cell-fusion and transdifferentiation has occurred. CONCLUSION: These observations provide in vitro evidence for spontaneous cell fusion and transdifferentiation of BMCs in co-culture, raising the possibility that the observed phenomenons may contribute to development or maintenance of these cell types.  相似文献   
8.
Objectives. Epididymal cystadenomas (ECs) are frequently found in association with von Hippel-Lindau disease (VHL), but little has been reported about their sonographic appearance. We review the sonographic appearance of ECs, the relationship of ECs to other manifestations of VHL, and the specific genetic mutations associated with ECs.Methods. Fifty-six male patients with VHL were examined with scrotal sonography and physical examination as part of a larger screening program for VHL. The head of the epididymis was measured in two planes on sonography and compared with age-matched normal controls. All VHL patients with palpable epididymal abnormalities or enlargement (more than two standard deviations) of the head of the epididymis on ultrasound were considered positive for EC.Results. Thirty of 56 (54%) male patients with VHL demonstrated a unilateral (n = 10; 33%) or bilateral (n = 20; 67%) solid abnormality in the head of the epididymis suggestive of EC. Sonographic appearances ranged from a solid mass with multiple tiny cysts to an almost completely solid mass. The most common appearance was a 15- to 20-mm solid mass with small cystic components. Dilated efferent ductules were seen within the testicle in 7 men, evidently a result of chronic obstruction. There was no association between the clinical subtype of VHL and the presence of ECs (P >0.10, chi square). Mutations resulting in a truncated gene product were associated with the development of ECs but the association did not reach statistical significance (P = 0.06).Conclusions. ECs are a common manifestation of VHL in men and exhibit a range of appearances on ultrasound. Sonography can be used to identify ECs and determine the extent of cystic dilation of the rete testes. The benign course of ECs and the usual absence of clinical symptoms favor a conservative approach to their management.  相似文献   
9.
We compare the expression of four markers of renal tubular differentiation in six renal cell carcinomas, five atypical renal cysts, and five simple renal cysts from six patients with von Hippel-Lindau disease. Proximal tubular markers were expressed by five of six renal cell carcinomas, three of five atypical renal cysts, and zero of five simple renal cysts. Distal tubular markers were expressed by one of six renal cell carcinomas, five of five atypical renal cysts, and four of five simple renal cysts. One of the three atypical cysts which expressed distal tubular markers was associated with a renal cell carcinoma which also expressed distal tubular markers. Our findings suggest that simple renal cysts in von Hippel-Lindau disease arise more commonly from distal rather than proximal tubules, while atypical renal cysts show tubular origin similar to renal cell carcinomas.  相似文献   
10.
Intraoperative penile tumescence during endoscopic surgery is a troublesome complication that often is refractory to recommended methods of management. We report a new approach of pharmacological management with intracorporeal penile injections of phenylephrine (total dose of 0.1 mg.), which was successful in 3 successive patients. This approach is prompt, safe and reproducible, and it provides sustained resolution of erection without systemic side effects. It is concluded that local intracorporeal penile administration of this sympathomimetic agent appears to be a potent new tool in the armamentarium of the endoscopic surgeon dealing with this frustrating clinical situation, which merits further clinical trial.  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