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   22981篇
  免费   1142篇
  国内免费   255篇
耳鼻咽喉   252篇
儿科学   481篇
妇产科学   667篇
基础医学   2609篇
口腔科学   522篇
临床医学   1692篇
内科学   6162篇
皮肤病学   397篇
神经病学   2482篇
特种医学   890篇
外科学   3652篇
综合类   45篇
一般理论   4篇
预防医学   908篇
眼科学   283篇
药学   1351篇
中国医学   48篇
肿瘤学   1933篇
  2024年   23篇
  2023年   184篇
  2022年   401篇
  2021年   712篇
  2020年   442篇
  2019年   522篇
  2018年   686篇
  2017年   556篇
  2016年   641篇
  2015年   717篇
  2014年   929篇
  2013年   1121篇
  2012年   1768篇
  2011年   1797篇
  2010年   1014篇
  2009年   1000篇
  2008年   1621篇
  2007年   1599篇
  2006年   1455篇
  2005年   1384篇
  2004年   1351篇
  2003年   1212篇
  2002年   1073篇
  2001年   155篇
  2000年   122篇
  1999年   164篇
  1998年   184篇
  1997年   165篇
  1996年   166篇
  1995年   126篇
  1994年   85篇
  1993年   95篇
  1992年   91篇
  1991年   70篇
  1990年   63篇
  1989年   78篇
  1988年   51篇
  1987年   64篇
  1986年   52篇
  1985年   37篇
  1984年   55篇
  1983年   48篇
  1982年   35篇
  1981年   41篇
  1980年   42篇
  1979年   19篇
  1978年   14篇
  1977年   20篇
  1976年   14篇
  1974年   14篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Objective: Intravesical Bacillus Calmette-Guèrin (BCG) is an effective treatment in non––muscle-invasive bladder cancer, however, extravesical BCG infection may occur in remote organs as a potentially serious complication. Researchers aimed to assess whether a different timing of BCG infection after intravesical administration of BCG could be identified and estimated for each single involved organ. Methods: We performed a systematic literature review over systemic and genitourinary BCG infection case reports, including 271 published case reports for a total of 307 patients. Demographic data, clinical features, and timing of BCG infection development were collected and analyzed for each patient. Results: BCG infection developed with a different timing from last instillation, depending on the involved organ. Among the genitourinary complications, penile lesions occurred as early as 1 (1;3) weeks, while orchiepididymitis occurred as late as 56 (6.25;156) weeks. At the same time, granulomatous hepatitis and lungs involvement such as miliary pulmonary BCG infection occurred earlier, with a median time of 1 (1;4) and 1 (1;6) weeks respectively, whereas vascular, osteoarticular, and muscular complications developed with a median timing from last instillation of 52 (20;104), 68 (14;156), and 93 (29;156) weeks, respectively. The analysis detected a cluster between lungs, liver, and bone marrow complications on one side and muscular and osteoarticular or vascular complications on the other side was also observed. Conclusions: BCG infection after intravesical BCG for bladder cancer may develop even several months or years after the last instillation, depending on the involved organs. When BCG infection interests one or more organ, 2 main associative patterns are common: one involving lungs, liver, and bone marrow, with earlier occurrence but lower rates of microbiological diagnosis achievement, and one involving muscular and osteoarticular or vascular districts, with later occurrence but higher rates of microbiological evidence.  相似文献   
992.
993.
994.
BackgroundPostoperative hyperamylasemia is a frequent finding after pancreatoduodenectomy, but its incidence and clinical implications have not yet been analyzed systematically. The aim of this review is to reappraise the concept of postoperative hyperamylasemia with postoperative acute pancreatitis, including its definition, interpretation, and correlation.MethodsOnline databases were used to search all available relevant literature published through June 2019. The following search terms were used: “pancreaticoduodenectomy,” “amylase,” and “pancreatitis.” Surgical series reporting data on postoperative hyperamylasemia or postoperative acute pancreatitis were selected and screened.ResultsAmong 379 screened studies, 39 papers were included and comprised data from a total of 9,220 patients. Postoperative hyperamylasemia was rarely defined in most of these series, and serum amylase values were measured at different cutoff levels and reported on different postoperative days. The actual levels of serum amylase activity and the representative cutoff levels required to reach a diagnosis of postoperative acute pancreatitis were markedly greater on the first postoperative days and tended to decrease over time. Most studies analyzing postoperative hyperamylasemia focused on its correlation with postoperative pancreatic fistula and other postoperative morbidities. The incidence of postoperative acute pancreatitis varied markedly between studies, with its definition completely lacking in 40% of the analyzed papers. A soft pancreatic parenchyma, a small pancreatic duct, and pathology differing from cancer or chronic pancreatitis were all predisposing factors to the development of postoperative hyperamylasemia.ConclusionPostoperative hyperamylasemia has been proposed as the biochemical expression of pancreatic parenchymal injury related to localized ischemia and inflammation of the pancreatic stump. Such phenomena, analogous to those associated with acute pancreatitis, could perhaps be renamed as postoperative acute pancreatitis from a clinical standpoint. Patients with postoperative acute pancreatitis experienced an increased rate of all postoperative complications, particularly postoperative pancreatic fistula. Taken together, the discrepancies among previous studies of postoperative hyperamylasemia and postoperative acute pancreatitis outlined in the present review may provide a basis for stronger evidence necessary for the development of universally accepted definitions for postoperative hyperamylasemia and postoperative acute pancreatitis.  相似文献   
995.
BackgroundThe occurrence of early graft failure (EGF) after heart transplantation (Htx) often requires a mechanical circulatory support (MCS) therapy. The aims of our study were to identify risk factors of mechanically supported severe EGF and evaluate their impact on both early and late outcomes.MethodsBetween January 2000 and December 2019, 499 consecutive adult patients underwent Htx at our institution. Severe EGF was defined as the need for extracorporeal life support (ECLS) within 24 hours after surgery. All available recipient and donor variables were retrospectively analyzed.ResultsOverall, EGF occurred in 58 (11.6%) patients. Post-Htx peripheral or central ECLS was necessary in 32 (6.4%) cases. Independent predictors of severe EGF were, in the recipient group, preoperative transpulmonary gradient (TPG) >12 mm Hg (odds ratio [OR] 4.1, P = .013), preoperative inotropic score >10 (OR 7.3, P = .0001), and pre-Htx ECLS support (OR 5.2, P = .015), while in the donors, a Eurotransplant donor score ≥17 (OR 8.5, P = .005). The absence of EGF was related with a better survival at 1 year and 5 years (94% and 85%, respectively) compared with EGF requiring ECLS population (36% and 28% at 1 year and 5 years, respectively; P < .001). A five-year conditional survival rate did not differ significantly (85% no EGF vs 83% EGF requiring ECLS).ConclusionBoth donor and recipient factors may influence EGF occurrence. Post-Htx ECLS may impact negatively early; however, patients weaned from ECLS eventually benefit from such a rescue treatment with outcomes comparable with Htx patients who did not suffer EGF.  相似文献   
996.
Although gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) have always been considered rare tumors, their incidence has risen over the past few decades. They represent a highly heterogeneous group of neoplasms with several prognostic factors, including disease stage, proliferative index (Ki67), and tumor differentiation. Most of these neoplasms express somatostatin receptors on the cell surface, a feature that has important implications in terms of prognosis, diagnosis, and therapy. Although International Guidelines propose algorithms aimed at guiding therapeutic strategies, GEP-NEN patients are still very different from one another, and the need for personalized treatment continues to increase. Radical surgery is always the best option when feasible; however, up to 80% of cases are metastatic upon diagnosis. Regarding medical treatments, as GEP-NENs are characterized by relatively long overall survival, multiple therapy lines are adopted during the lifetime of these patients, but the optimum sequence to be followed has never been clearly defined. Furthermore, although new molecular markers aimed at predicting the response to therapy, as well as prognostic scores, are currently being studied, their application is still far from being part of daily clinical practice. As they represent a complex disease, with therapeutic protocols that are not completely standardized, GEP-NENs require a multidisciplinary approach. This review will provide an overview of the available therapeutic options for GEP-NENs and attempts to clarify the possible approaches for the management of these patients and to discuss future perspectives in this field.  相似文献   
997.

Background  

This retrospective study compares the results of primary gastric bypass (PGB) versus secondary gastric bypass (SGB) performed after gastroplasty.  相似文献   
998.
The DSM-IV diagnoses generated by the fully structured lay-administered Composite International Diagnostic Interview Version 3.0 (CIDI 3.0) in the WHO World Mental Health (WMH) surveys were compared to diagnoses based on follow-up interviews with the clinician-administered non-patient edition of the Structured Clinical Interview for DSM-IV (SCID) in probability subsamples of the WMH surveys in France, Italy, Spain, and the US. CIDI cases were oversampled. The clinical reappraisal samples were weighted to adjust for this oversampling. Separate samples were assessed for lifetime and 12-month prevalence. Moderate to good individual-level CIDI-SCID concordance was found for lifetime prevalence estimates of most disorders. The area under the ROC curve (AUC, a measure of classification accuracy that is not influenced by disorder prevalence) was 0.76 for the dichotomous classification of having any of the lifetime DSM-IV anxiety, mood and substance disorders assessed in the surveys and in the range 0.62-0.93 for individual disorders, with an inter-quartile range (IQR) of 0.71-0.86. Concordance increased when CIDI symptom-level data were added to predict SCID diagnoses in logistic regression equations. AUC for individual disorders in these equations was in the range 0.74-0.99, with an IQR of 0.87-0.96. CIDI lifetime prevalence estimates were generally conservative relative to SCID estimates. CIDI-SCID concordance for 12-month prevalence estimates could be studied powerfully only for two disorder classes, any anxiety disorder (AUC = 0.88) and any mood disorder (AUC = 0.83). As with lifetime prevalence, 12-month concordance improved when CIDI symptom-level data were added to predict SCID diagnoses. CIDI 12-month prevalence estimates were unbiased relative to SCID estimates. The validity of the CIDI is likely to be under-estimated in these comparisons due to the fact that the reliability of the SCID diagnoses, which is presumably less than perfect, sets a ceiling on maximum CIDI-SCID concordance.  相似文献   
999.
OBJECTIVE: A relationship between brain atrophy and delta rhythmicity (1.5-4 Hz) has been previously explored in Alzheimer's disease (AD) subjects [Fernandez A, Arrazola J, Maestu F, Amo C, Gil-Gregorio P, Wienbruch C, Ortiz T. Correlations of hippocampal atrophy and focal low-frequency magnetic activity in Alzheimer disease: volumetric MR imaging-magnetoencephalographic study. Am J Neuroradiol. 2003 24(3):481-487]. In this study, we tested the hypothesis that such a relationship does exist not only in AD patients but also across the continuum of subjects with mild cognitive impairment (MCI) and AD. METHODS: Resting, eyes-closed EEG data were recorded in 34 MCI and 65 AD subjects. EEG rhythms of interest were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). EEG cortical sources were estimated by LORETA. Cortical EEG sources were correlated with MR-based measurements of lobar brain volume (white and gray matter). RESULTS: A negative correlation was observed between the frontal white matter and the amplitude of frontal delta sources (2-4 Hz) across MCI and AD subjects. CONCLUSIONS: These results confirmed for the first time the hypothesis that the sources of resting delta rhythms (2-4 Hz) are correlated with lobar brain volume across MCI and AD subjects. SIGNIFICANCE: The present findings support, at least at group level, the 'transition hypothesis' of brain structural and functional continuity between MCI and AD.  相似文献   
1000.
The levels of the soluble (s) CD40:sCD40 ligand (L) dyad, which belongs to the tumor necrosis factor (TNF)-alpha:TNF-alpha-receptor superfamily, are significantly increased in the cerebrospinal fluid (CSF), but not the serum of cobalamin (Cbl)-deficient (Cbl-D) rats. They were normalized or significantly reduced after treatment with Cbl, transforming growth factor-beta1 or S-adenosyl-L-methionine, and the normal myelin ultrastructure of the spinal cord was concomitantly restored. The concomitance of the two beneficial effects of these treatments strongly suggests that the increases in CSF sCD40:sCD40L levels may participate in the pathogenesis of purely myelinolytic Cbl-D central neuropathy in the rat. In keeping with this, an anti-CD40 treatment prevented myelin lesions.  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