全文获取类型
收费全文 | 3565篇 |
免费 | 237篇 |
国内免费 | 15篇 |
专业分类
耳鼻咽喉 | 32篇 |
儿科学 | 171篇 |
妇产科学 | 84篇 |
基础医学 | 407篇 |
口腔科学 | 137篇 |
临床医学 | 376篇 |
内科学 | 662篇 |
皮肤病学 | 186篇 |
神经病学 | 293篇 |
特种医学 | 196篇 |
外科学 | 397篇 |
综合类 | 32篇 |
一般理论 | 2篇 |
预防医学 | 293篇 |
眼科学 | 18篇 |
药学 | 343篇 |
中国医学 | 4篇 |
肿瘤学 | 184篇 |
出版年
2021年 | 42篇 |
2020年 | 28篇 |
2019年 | 39篇 |
2018年 | 66篇 |
2017年 | 41篇 |
2016年 | 56篇 |
2015年 | 61篇 |
2014年 | 78篇 |
2013年 | 126篇 |
2012年 | 123篇 |
2011年 | 139篇 |
2010年 | 98篇 |
2009年 | 78篇 |
2008年 | 149篇 |
2007年 | 163篇 |
2006年 | 157篇 |
2005年 | 122篇 |
2004年 | 109篇 |
2003年 | 127篇 |
2002年 | 120篇 |
2001年 | 123篇 |
2000年 | 129篇 |
1999年 | 124篇 |
1998年 | 49篇 |
1997年 | 54篇 |
1996年 | 48篇 |
1995年 | 45篇 |
1994年 | 43篇 |
1993年 | 28篇 |
1992年 | 73篇 |
1991年 | 74篇 |
1990年 | 84篇 |
1989年 | 90篇 |
1988年 | 77篇 |
1987年 | 79篇 |
1986年 | 70篇 |
1985年 | 71篇 |
1984年 | 48篇 |
1983年 | 49篇 |
1982年 | 29篇 |
1981年 | 30篇 |
1980年 | 30篇 |
1979年 | 39篇 |
1978年 | 32篇 |
1977年 | 37篇 |
1976年 | 27篇 |
1975年 | 29篇 |
1972年 | 34篇 |
1971年 | 26篇 |
1969年 | 28篇 |
排序方式: 共有3817条查询结果,搜索用时 15 毫秒
61.
The serum antibody titers against Escherichia coli and/or Proteus mirabilis were elevated in 26 of 80 patients (33%) with a conduit urinary diversion. Urographic findings were abnormal in 44 of these 80 patients (55%). Urography was normal in 59% of the patients with normal antibody titers, but in only 15% of those with elevated titers. Raised antibody levels against E. coli O antigen (greater than 256 before and/or greater than 32 after mercaptoethanol treatment of serum) were associated with wide upper urinary tract or calculi more often than were normal E. coli antibody titers. Raised titers against P. mirabilis (greater than 256 before and/or greater than 32 after mercaptoethanol treatment of serum) were associated with scarring of the renal parenchyma more frequently than were normal titers. A statistically significant association was found between "small" kidney area and raised serum antibody titers against E. coli or P. mirabilis. The frequency of "small" kidney increased with the time lapse after urinary diversion. At 3 to 11 months postoperatively it was 29%, but among the patients with urinary diversion for more than five years the corresponding frequency was 82%. When at least one kidney was "small", the serum creatinine was higher than when both kidneys were of normal size. Patients with raised antibody titers tended also to have high serum creatinine (greater than or equal to 124 mumol/l) more often than those with normal titers (23 vs. 10%). These observations imply a connection between elevation of the antibody titers and destruction of the renal parenchyma in patients with conduit urinary diversion. They illustrate the value of antibody titration in the follow-up of patients with urinary diversion. 相似文献
62.
Appendicitis associated with recent barium study. 总被引:1,自引:0,他引:1
There have been several reports of "barium-induced" appendicitis in the literature. When confronted with a possible case of this phenomenon, a review of the literature on the subject was carried out. The suggestion is made that there is no evidence to support a cause-effect relationship between barium retained in the appendix and appendicitis. Diseased appendices can be marked by retained barium and a higher likelihood may then exist for the subsequent development of appendicitis. Following the finding of prolonged retention of barium after contrast study, it is recommended that the patient be instructed as to the possibility of developing symptoms of acute appendicitis. Patients who present with symptoms of appendicitis should be questioned as to history of recent barium study, and x-rays should be reviewed with the possibility of finding appendoliths. 相似文献
63.
Striatal dopamine transporter binding in neuroleptic-naive patients with schizophrenia studied with positron emission tomography 总被引:3,自引:0,他引:3
Laakso A Vilkman H Alakare B Haaparanta M Bergman J Solin O Peurasaari J Räkköläinen V Syvälahti E Hietala J 《The American journal of psychiatry》2000,157(2):269-271
OBJECTIVE: Recent in vivo imaging studies indicate a dysregulated presynaptic function of the striatal dopaminergic system in patients with schizophrenia. To further explore the basis of this phenomenon, the authors studied brain dopamine transporter binding in vivo in patients with first-episode, never-medicated schizophrenia. METHOD: Nine patients with schizophrenia and nine healthy matched comparison subjects were recruited. Striatal dopamine transporter binding was measured with positron emission tomography and a specific dopamine transporter ligand, [(18)F]CFT, a radiolabeled form of 2beta-carbomethoxy-3beta-(4-fluorophenyl)tropane. RESULTS: Average caudate and putamen dopamine transporter binding potentials were almost identical in the patients and comparison subjects, but the patients lacked the right-left asymmetry of the caudate dopamine transporter binding seen in the comparison group. CONCLUSIONS: Average striatal dopamine transporter density is unaltered in neuroleptic-naive patients with schizophrenia. However, patients lack asymmetry in caudate dopamine transporter binding, which conforms with disrupted brain lateralization in this disorder. 相似文献
64.
BACKGROUND: Heme oxygenase-1 (HO-1) is a 32-kDa stress protein that catalyzes the degradation of heme to biliverdin. HO-1 immunoreactivity is greatly increased in neurons and astrocytes of the hippocampus and cerebral cortex of individuals with AD and colocalizes to senile plaques and neurofibrillary tangles. METHODS: We investigated whether systemic HO-1 regulation is also deranged in AD patients and whether blood HO-1 measurements provide a peripheral biomarker of the disease. Plasma HO-1 protein levels were measured by competitive ELISA and lymphocyte HO-1 mRNA levels were determined by Northern analysis in patients with early probable sporadic AD, normal elderly controls (NEC), normal younger controls, individuals with age-associated cognitive decline (AACD) not meeting AD criteria, and patients with non-Alzheimer dementia, nondementing neurologic illness, and chronic medical disorders. CSF HO-1 protein concentrations were also determined by ELISA in pathologically confirmed AD and control cases. RESULTS: Mean plasma HO-1 protein concentrations were significantly lower in AD patients (0.85 +/- 0.14 microg/mL) compared with NEC (1.77 +/- 0.34 microg/mL; p < 0.05) and control patients. The AACD group exhibited plasma HO-1 concentrations (1.06 +/- 0.33 microg/mL) intermediate between, but not different from, those of the AD patients and NEC. Lymphocyte HO-1 mRNA levels were lower in the AD cohort relative to NEC (p < 0.001) and individuals with AACD, non-Alzheimer dementia, nondementing neurologic illness, and chronic medical conditions. Lymphocyte HO-1 mRNA levels were also lower in the AACD group relative to NEC (p < 0.05). In comparison with all groups excluding AACD, the sensitivity and specificity of lymphocyte HO-1 mRNA measurement for diagnosis of early sporadic AD are 88% and 75%. Mean CSF HO-1 protein concentrations were lower (p < 0.01) in AD cases (19.07 ng/mL) relative to control values (32.48 ng/mL). CONCLUSIONS: Plasma and CSF HO-1 protein and lymphocyte HO-1 mRNA levels are decreased in subjects with sporadic AD. Quantitative assay for lymphocyte HO-1 mRNA expression may serve as a useful biologic marker in early sporadic AD. 相似文献
65.
66.
Ulrik N Lassen Fred R Hirsch Kell Østerlind Bengt Bergman Per Dombernowsky 《Lung cancer (Amsterdam, Netherlands)》1998,20(3):151-160
During the past two decades many different treatment regimens of combination chemotherapy have been applied in extensive stage small-cell lung cancer (SCLC). This study was carried out to identify whether these modifications have resulted in an improved overall survival for extensive stage during the past two decades. In total, 1111 patients with extensive stage SCLC were included in six consecutive randomised trials in our setting from 1973 until 1992. Of these, 526 patients treated in the early period (1973–1981) were compared with 585 patients treated in the late period (1981–1992) with respect to pretreatment prognostic factors, staging, treatment and outcome. No change in the distribution of prognostic factors was detected and the frequency of patients with extensive stage was equal in the two periods, and no difference in overall response rates and survival was observed (P=0.49). Median survival in the two periods was 208 days and 215 days, respectively. No stage migration or treatment-related improved outcome was observed in extensive disease. We suggest restricting aggressive treatment to patients with favorable prognosis and long-term survival as a realistic aim. 相似文献
67.
Dahlman P Semenas E Brekkan E Bergman A Magnusson A 《Acta radiologica (Stockholm, Sweden : 1987)》2000,41(4):361-366
Purpose: The fast helical CT technique allows examination of the kidneys during different phases of contrast medium enhancement. However, every additional phase increases the radiation dosage to the patients. We investigated the detection rate and characterisation of renal lesions during different phases and evaluated them separately, and considered the possibility of excluding phases without loss of important information.Material and Methods: Sixty patients who underwent contrast-enhanced multiphasic renal helical CT examination were included. Every CT phase was evaluated separately. The number of lesions and the characteristics of the lesions were noted and all lesions were viewed together.Results: A total of 153 cysts and 17 solid lesions were detected. The largest and an equal number of cysts (142/143) was detected in the nephrographic and excretory phases. However, the nephrographic phase detected more cortical cysts and the excretory phase detected more sinus cysts. All solid lesions were detected in all phases. Renal parenchymal tumours were best characterised in the cortical phase and angiomyolipomas in the native phase.Conclusion: The cortical phase was best for characterisation of renal parenchymal tumours. The nephrographic and excretory phases were best in detecting and characterising renal cysts. The nephrographic phase was the phase giving the least diagnostic information. 相似文献
68.
69.
Accurate measurement of endogenous insulin secretion does not require separate assessment of C-peptide kinetics 总被引:1,自引:0,他引:1
The implication of beta-cell failure as an early defect in type 2 diabetes exacerbates the need for accurate but facile assessment of islet cell secretory rate, particularly in large group studies in which individual assessment of C-peptide kinetics is impractical. This study was designed to examine whether it is possible to obtain accurate secretory rates from the extended combined model, which provides insulin and C-peptide kinetics from plasma measurements of the two peptides. Equimolar intraportal infusions of insulin and C-peptide that are designed to simulate insulin secretion rates during both oral and intravenous glucose tolerance tests were used to generate plasma insulin and C-peptide data in conscious dogs that were examined under clamped glucose conditions. The plasma peptide kinetics were analyzed using the extended combined model to generate estimates of prehepatic insulin secretion that were then compared with the known intraportal infusion rates. The extended combined model was able to reproduce the known intraportal infusion profiles. The model-predicted rates were similar to those calculated with methods that require separate assessment of C-peptide kinetics. Simulation results supported lesser clearance of insulin during rapid changes of portal insulin (as measured by an intravenous glucose tolerance test) versus slow changes in portal insulin (as measured by an oral glucose tolerance test). The extended combined model accurately calculates prehepatic insulin appearance. It may be possible to apply this approach to large studies of beta-cell function designed to identify changes in islet function in subjects at risk for diabetes. Such an approach could strengthen epidemiological and genetic studies of the pathogenesis of diabetes. 相似文献
70.
Xinmeng Liao Yawen Lan Rui Shao Jiayu Liu Shufei Liang Zhan Yin Gudmundur H. Gudmundsson Peter Bergman Min Wan 《Journal of innate immunity》2022,14(3):229
Vitamin D (VD) is a major regulator of calcium metabolism in many living organisms. In addition, VD plays a key role in regulating innate and adaptive immunity in vertebrates. Neutrophils constitute an important part of the first line of defense against invading microbes; however, the potential effect of VD on neutrophils remains elusive. Thus, in this study zebrafish in different developmental stages were utilized to identify the potential role of VD in the basal homeostasis and functions of neutrophils. Our results showed that addition of exogenous VD<sub>3</sub> promoted granulopoiesis in zebrafish larvae. Reciprocally, neutrophil abundance in the intestine of adult zebrafish with a cyp2r1 mutant, lacking the capacity to 25-hydroxylate VD, was reduced. Moreover, VD-mediated granulopoiesis was still observed in gnotobiotic zebrafish larvae, indicating that VD regulates neutrophil generation independent of the microbiota during early development. In contrast, VD was incapable to influence granulopoiesis in adult zebrafish when the commensal bacteria were depleted by antibiotic treatment, suggesting that VD might modulate neutrophil activity via different mechanisms depending on the developmental stage. In addition, we found that VD<sub>3</sub> augmented the expression of il-8 and neutrophil recruitment to the site of caudal fin amputation. Finally, VD<sub>3</sub> treatment significantly decreased bacterial counts and mortality in zebrafish infected with Edwardsiella tarda (E. tarda) in a neutrophil-dependent manner. Combined, these findings demonstrate that VD regulates granulopoiesis and neutrophil function in zebrafish immunity. 相似文献