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   11310篇
  免费   477篇
  国内免费   107篇
耳鼻咽喉   111篇
儿科学   447篇
妇产科学   250篇
基础医学   1274篇
口腔科学   301篇
临床医学   836篇
内科学   2417篇
皮肤病学   271篇
神经病学   916篇
特种医学   586篇
外科学   1282篇
综合类   64篇
一般理论   2篇
预防医学   1315篇
眼科学   498篇
药学   808篇
  2篇
中国医学   20篇
肿瘤学   494篇
  2023年   26篇
  2022年   12篇
  2021年   54篇
  2020年   47篇
  2019年   72篇
  2018年   131篇
  2017年   84篇
  2016年   92篇
  2015年   140篇
  2014年   153篇
  2013年   217篇
  2012年   676篇
  2011年   824篇
  2010年   311篇
  2009年   238篇
  2008年   795篇
  2007年   891篇
  2006年   847篇
  2005年   893篇
  2004年   826篇
  2003年   750篇
  2002年   678篇
  2001年   557篇
  2000年   630篇
  1999年   298篇
  1998年   171篇
  1997年   180篇
  1996年   163篇
  1995年   123篇
  1994年   125篇
  1993年   117篇
  1992年   51篇
  1991年   54篇
  1990年   50篇
  1989年   67篇
  1988年   68篇
  1987年   49篇
  1986年   56篇
  1985年   52篇
  1984年   32篇
  1983年   26篇
  1982年   32篇
  1981年   33篇
  1980年   29篇
  1979年   7篇
  1978年   10篇
  1977年   25篇
  1976年   27篇
  1975年   16篇
  1974年   8篇
排序方式: 共有10000条查询结果,搜索用时 98 毫秒
71.
The goal of this study was to determine whether sequence analysis of internal transcribed spacer/5.8S ribosomal DNA (rDNA) can be used to detect fungal pathogens in patients with ocular infections (endophthalmitis and keratitis). Internal transcribed spacer 1 (ITS1) and ITS2 and 5.8S rDNA were amplified by PCR and seminested PCR to detect fungal DNA. Fifty strains of 12 fungal species (yeasts and molds) were used to test the selected primers and conditions of the PCR. PCR and seminested PCR of this region were carried out to evaluate the sensitivity and specificity of the method. It proved possible to amplify the ITS2/5.8S region of all the fungal strains by this PCR method. All negative controls (human and bacterial DNA) were PCR negative. The sensitivity of the seminested PCR amplification reaction by DNA dilutions was 1 organism per PCR, and the sensitivity by cell dilutions was fewer than 10 organisms per PCR. Intraocular sampling or corneal scraping was undertaken for all patients with suspected infectious endophthalmitis or keratitis (nonherpetic), respectively, between November 1999 and February 2001. PCRs were subsequently performed with 11 ocular samples. The amplified DNA was sequenced, and aligned against sequences in GenBank at the National Institutes of Health. The results were PCR positive for fungal primers for three corneal scrapings, one aqueous sample, and one vitreous sample; one of them was negative by culture. Molecular fungal identification was successful in all cases. Bacterial detection by PCR was positive for three aqueous samples and one vitreous sample; one of these was negative by culture. Amplification of ITS2/5.8S rDNA and molecular typing shows potential as a rapid technique for identifying fungi in ocular samples.  相似文献   
72.
BACKGROUND: Food allergy may be life-threatening, and patients affected need to receive accurate diagnoses and treatment. Hazelnut has often been implicated as responsible for allergic reactions, and trace quantities can induce systemic reactions. OBJECTIVE: The aim of this study was to evaluate the efficacy and tolerance of sublingual immunotherapy with a standardized hazelnut extract in patients allergic to hazelnut. METHODS: This was a randomized, double-blind, placebo-controlled study. Inclusion criteria were a history of hazelnut allergy and positive skin prick test and double-blind placebo-controlled food challenge results. Patients were then randomly assigned into 2 treatment groups (hazelnut immunotherapy or placebo). Efficacy was assessed by double-blind, placebo-controlled food challenge after 8 to 12 weeks of treatment. Blood samples were drawn for measurement of specific IgE, IgG(4), and serum cytokines before and after treatment. RESULTS: Twenty-three patients were enrolled and divided into 2 treatment groups. Twenty-two patients reached the planned maximum dose at 4 days. Systemic reactions were observed in only 0.2% of the total doses administered. Mean hazelnut quantity provoking objective symptoms increased from 2.29 g to 11.56 g (P = .02; active group) versus 3.49 g to 4.14 g (placebo; NS). Moreover, almost 50% of patients who underwent active treatment reached the highest dose (20 g), but only 9% in the placebo. Laboratory data showed an increase in IgG(4) and IL-10 levels after immunotherapy in only the active group. CONCLUSION: Our data confirm significant increases in tolerance to hazelnut after sublingual immunotherapy as assessed by double-blind, placebo-controlled food challenge, and good tolerance to this treatment.  相似文献   
73.
The prion protein in human neuromuscular diseases   总被引:2,自引:0,他引:2  
The basis of human prion diseases affecting the nervous system is accumulation of a disease-associated conformer (PrPSc) of the normal cellular prion protein (PrPC). Earlier studies demonstrated increased expression of PrPC in inclusion body myositis (IBM), dermato-, and polymyositis, as well as neurogenic muscle atrophy. To define the spectrum and reliability of PrPC immunoreactivity, its expression was examined systematically in a series of pathologically characterized muscular disorders by means of immunohistochemistry, confocal laser microscopy, and immunogold electron microscopy. Anti-PrPC immunolabelling of rimmed vacuoles was observed in IBM, inclusions of myofibrillary myopathy, targets, regenerating, and atrophic fibres, mononuclear cells, in addition to ragged red fibres in mitochondrial myopathies, and focal sarcolemmal immunostaining in non-diseased controls. Quantitative analysis demonstrated that, in neurogenic muscle lesions, anti-PrPC staining detects a significantly broader spectrum of fibres than anti-vimentin or anti-NCAM. In dystrophic muscle, PrPC expression was mainly restricted to regenerating fibres. In IBM, PrPC expression was not confined to rimmed vacuoles or vacuolated fibres and only a small percentage (7.1%) of rimmed vacuoles were PrPC positive. Ultrastructurally, PrPC was observed in the cytoplasm of lymphocytes, in the myofibrillar network of targets, and in rimmed vacuoles. Knowledge of disease circumstances with altered expression of PrPC is important in the setting of a potentially increased chance for extraneural PrPC-PrPSc conversion. In addition, our observations suggest that PrPC may have a general stress-response effect in various neuromuscular disorders.  相似文献   
74.
Among other characteristics, the steady-state current-voltage relationship of patch-clamped single atrial myocytes from guinea-pig hearts is defined by an outward current hump in the potential region –15 to +40mV. This hump was reversibly suppressed by Co2+ (3 mM) or nitrendipine (5 M) and enhanced by Bay K 8644 (5 M). The maintained outward current component suppressed by Co2+ extended between –15.2±1.9 mV and +39.5 ±1.7 mV (mean±SEM of 14 cells) and has an amplitude of 95.7±9.4 pA at +10 mV. In isochronal I-V curves, the hump was already visible at 400 ms with essentially the same amplitude as at 1500 ms. The Co2+ -sensitive outward current underlying the hump was poorly time-dependent during 1.5 s voltage pulses but slowly relaxed upon repolarization. Tail currents reversed near the K+ equilibrium potential under our experimental conditions. The current hump of the steady-state I-V curve was also abolished by caffeine (10 mM) or ryanodine (3 M), both drugs that interfere with sarcoplasmic reticulum function. Apamin (1 M) or quinine (100 M) but not TEA (5–50 mM) markedly reduced its amplitude. However, at similar concentrations as required to inhibit the hump, both apamin and quinine appeared to be poorly specific for Ca2+ -activated K+ currents in heart cells since they also inhibited the L-Type Ca2+ current. It is concluded that a long lasting Ca2+ -activated outward current, probably mainly carried by K+ ions but not sensitive to TEA, exists in atrial myocytes which is responsible for the current hump of the background I-V curve.  相似文献   
75.
Summary Cephalic pancreatoduodenectomy (CPD) with pylorus preservation has been suggested to improve the functional and nutritional result of surgery. At operation, the first two centimeters of the duodenum are preserved, the vascular arch of the lesser gastric curvature is saved and the right gastroepiploic artery is resected at its origin. The aim of this study on 15 fresh cadavers was to determine the origin of the vascularization of the remaining duodenum and also the possibilities of preserving an optimal vascularization after CPD and pylorus preservation. All of the arteries supplying the remaining duodenum and arising either from the right gastric artery or the right gastroepiploic artery were identified. The distances between the origin of the infrapyloric artery and the termination of the gastroduodenal artery on the cranial and ventral pancreaticoduodenal artery and the left gastroepiploic artery were measured. At CPD with pylorus preservation, the study demonstrated that: 1) the cranial side of the remaining duodenum remains vascularized in 80% of the cases by one or two supraduodenal branches coming from the right gastric artery; 2) ligation of the right gastroepiploic artery eliminates all vascular supply to the caudal side of the remaining duodenum in almost half of the cases; 3) in these cases, the dissection of the bifurcation of the gastroduodenal artery and the vascular section beyond the origin of the infrapyloric artery allowed a direct vascular supply to the remaining duodenum to be preserved.This work was presented at the French Section of the European Association of Clinical Anatomy meeting, Bobigny, France, 1992  相似文献   
76.
Fibronectin was detected by immunofluorescence technique on the surface of one part of separated normal peripheral blood lymphocytes by using FITC-conjugated anti-human fibronectin antibodies. Approximately one-fifth of isolated B cells and 7% of O cells contained surface-bound fibronectin but T cells failed to stain. There were no detectable free receptors for fibronectin on the surface of lymphocytes of different subsets as it was studied with FITC-labelled purified fibronectin. The percent of B and O cells bearing surface bound fibronectin was markedly decreased in patients with acute and chronic lymphocytic leukemias.  相似文献   
77.
BACKGROUND: The identification of 'unknown' allergic sensitizations may determine the prognosis and treatment of patients with respiratory airway disease. Currently, the presence in homes of 'exotic' animals as pets is increasing. In this article the Siberian hamster or dwarf hamster (Phodopus sungorus) was identified as a new indoor source of aeroallergens and respiratory disease. METHODS: The subjects were six outpatients who were treated for asthma and rhinitis. Siberian hamster hair extract was prepared with a standard wt/vol method, and patients were skin-prick tested with the extract. Serum-specific immunoglobulin (Ig)E against the Siberian hamster, common hamster (Cricetus cricetus) and golden hamster (Mesocricetus auratus) was determined. IgE-immunoblotting was also performed for all six sera. Specific bronchial challenge was carried out with the Siberian hamster extract. RESULTS: Skin prick tests (SPT) with the Siberian hamster extract, and specific IgE-antibodies against Siberian hamster, were strongly positive in all six patients. Determinations of specific IgE-antibodies against C. cricetus and M. auratus were negative in all patients. IgE-immunoblotting of the sera revealed two IgE-binding fractions (MW 18 and 32 kDa) in five of the six sera. Specific bronchial provocation tests resulted in early asthmatic responses in the two patients who were challenged. CONCLUSIONS: The present study reveals the Siberian hamster to be able to induce both sensitization and disease, and this species of hamster should be taken into consideration as a cause of respiratory disease in exposed subjects. A noteworthy finding was the lack of sensitization in our patients to common hamster allergens (M. auratus and C. cricetus) that are usually tested when hamster allergy is suspected.  相似文献   
78.
BACKGROUND: Since treatment approaches thought to be useful for mania are presumably suitable for hypomania as well, little systematic research has been done on the treatment of hypomanic episodes and their long-term outcome. As systematic trials have shown that the atypical antipsychotic risperidone may be effective and safe in the treatment of acute mania, we decided to conduct an open-label study of its effectiveness and tolerability in hypomania associated with bipolar II. METHODS: Forty-four DSM-IV bipolar II patients with Young Mania Rating Scale (YMRS) scores above 7 were included and followed-up for 6 months. Efficacy was measured by means of the YMRS and the Clinical Global Impression for Bipolar Disorder (CGI-BD). Treatment-emergent depression was measured by the Hamilton Depression Rating Scale (HDRS-17), and the Udvalg for Kliniske Unders?gelser (UKU) subscale was used for neurological/extrapyramidal side-effects. RESULTS: Thirty-four patients completed the trial. The mean dose of risperidone at endpoint was 2.8 mg/day. Last observation-carried-forward analysis showed significant reduction of YMRS scores from the first week of treatment, which continued until the endpoint (P<0.0001). At 6-month follow-up, 60% of patients were assymptomatic according to the CGI. The 32% who received risperidone in monotherapy seemed to respond equally well. Risperidone, as used in this study, appeared to be most protective against hypomanic than depressive recurrences. Nine patients (12%) had a depressive relapse during 6-month follow-up, one patient (2%) had an hypomanic relapse and another (2%) had both. No patients developed tardive dyskinesia during the duration of the study. Although most patients received risperidone in combination with standard mood-stabilizers, only three patients discontinued risperidone because of other side-effects. LIMITATIONS: In the absence of a placebo arm, it is uncertain to what extent the foregoing results could be ascribed to spontaneous remission of bipolar II disorder. CONCLUSIONS: Risperidone, either in combination with mood-stabilizers or alone was well-tolerated in bipolar II patients, who presented in a hypomanic state, and appeared efficacious. Further controlled research on the role of atypical antipsychotics in the treatment of less-than-manic forms of bipolar illness is warranted.  相似文献   
79.
80.
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