全文获取类型
收费全文 | 58585篇 |
免费 | 4915篇 |
国内免费 | 111篇 |
专业分类
耳鼻咽喉 | 662篇 |
儿科学 | 1514篇 |
妇产科学 | 1250篇 |
基础医学 | 7621篇 |
口腔科学 | 1352篇 |
临床医学 | 6422篇 |
内科学 | 11474篇 |
皮肤病学 | 878篇 |
神经病学 | 6348篇 |
特种医学 | 2718篇 |
外国民族医学 | 4篇 |
外科学 | 8576篇 |
综合类 | 795篇 |
一般理论 | 36篇 |
预防医学 | 4999篇 |
眼科学 | 1472篇 |
药学 | 3784篇 |
2篇 | |
中国医学 | 66篇 |
肿瘤学 | 3638篇 |
出版年
2021年 | 895篇 |
2020年 | 552篇 |
2019年 | 862篇 |
2018年 | 985篇 |
2017年 | 872篇 |
2016年 | 924篇 |
2015年 | 1065篇 |
2014年 | 1345篇 |
2013年 | 2074篇 |
2012年 | 2935篇 |
2011年 | 3100篇 |
2010年 | 1695篇 |
2009年 | 1557篇 |
2008年 | 2782篇 |
2007年 | 2965篇 |
2006年 | 2805篇 |
2005年 | 2618篇 |
2004年 | 2470篇 |
2003年 | 2304篇 |
2002年 | 2301篇 |
2001年 | 1634篇 |
2000年 | 1612篇 |
1999年 | 1448篇 |
1998年 | 630篇 |
1997年 | 590篇 |
1996年 | 540篇 |
1995年 | 512篇 |
1994年 | 446篇 |
1993年 | 397篇 |
1992年 | 1197篇 |
1991年 | 1203篇 |
1990年 | 1124篇 |
1989年 | 1126篇 |
1988年 | 939篇 |
1987年 | 1053篇 |
1986年 | 969篇 |
1985年 | 982篇 |
1984年 | 779篇 |
1983年 | 648篇 |
1982年 | 419篇 |
1981年 | 389篇 |
1980年 | 390篇 |
1979年 | 710篇 |
1978年 | 537篇 |
1977年 | 458篇 |
1976年 | 469篇 |
1975年 | 406篇 |
1974年 | 531篇 |
1973年 | 464篇 |
1972年 | 391篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
952.
953.
954.
955.
956.
Jay PortnoyGinger L. Chew ScD Wanda PhipatanakulP. Brock Williams PhD Carl GrimesKevin Kennedy MPH Elizabeth C. MatsuiJ. David Miller PhD David BernsteinJoann Blessing-Moore MD Linda CoxDavid Khan MD PhD David LangRichard Nicklas MD John OppenheimerChristopher Randolph MD Diane SchullerSheldon Spector MD Stephen A. TillesDana Wallace MD James SeltzerJames Sublett MD 《The Journal of allergy and clinical immunology》2013
957.
Susan A. Fiscus Takesha McMillion Julie A. E. Nelson William C. Miller 《Journal of clinical microbiology》2013,51(12):4137-4140
The qualitative Roche HIV-1 DNA Amplicor assay has been used for the past 20 years to diagnose HIV infection in infants and young children but is being phased out; hence, alternative assays must be found. The Gen-Probe Aptima qualitative HIV-1 RNA assay is currently the only FDA-cleared HIV-1 nucleic acid assay approved for diagnosis, but data on the use of this assay with infant plasma are limited. We assessed Aptima''s performance using control material for reproducibility and limit of detection and 394 plasma samples (0.2 to 0.5 ml) from HIV-exposed infected and uninfected infants and children for analytical sensitivity and specificity. Assays to assess within-run repeatability and between-run reproducibility indicated that the controls with 10,000 (5 of 5), 200 (5 of 5), 100 (16 of 16), 50 (12 of 12), and 25 (20 of 20) HIV-1 RNA copies/ml (cp/ml) were always positive, and negatives were always negative (20 of 20). The limit of detection was 14 cp/ml, as determined by probit analysis. The analytic sensitivity of the assay was 99.5% (189/190 samples; 95% confidence interval [CI], 97.1 to 99.9%) and specificity was 99.5% (199/200 samples; 95% CI, 97.2 to 99.9%). These results suggest that the assay is suitable for early infant diagnosis of HIV-1. 相似文献
958.
Jingti Deng Jonathan R. Lamb Astrid P. Mckeown Sam Miller Pierandrea Muglia Paul C. Guest Sabine Bahn Enrico H. Domenici Hassan Rahmoune 《Journal of affective disorders》2013
Background
Changes in circulatory aminopeptidases [dipeptidyl-peptidase-IV (DPP-IV), Prolyl-oligopeptidase (POP) and Leucine aminopeptidase (LAP)] activities have been found to be associated with psychiatric illnesses and inflammatory diseases.Methods
The discriminatory indices of aminopeptidases activities were assessed by enzymatic assays in plasma samples from 240 unipolar depression (UD) patients and 264 matched controls. In addition the relationship between soluble and cellular DPP-IV activity was determined in plasma and blood cells from healthy subjects.Results
Greater than 95% of the plasma DPP-IV activity could be blocked by inhibitors, demonstrating the specificity of the assay. Also, DPP-IV protein and activity levels were strongly correlated. In contrast, only 50% of the membrane-bound activity in blood cells was inhibited, which suggested that other similar peptidases may be present in these cells. UD patients had decreased plasma levels of DPP-IV and POP activities compared to healthy controls with a concomitant increase in LAP activity. Finally, testing of the LAP/DPP-IV ratio resulted in good discrimination of UD patients from controls with an area under the curve—receiver operating characteristic of 0.70.Limitations
Further biological validation studies using different cohorts are warranted.Conclusions
The finding that plasma DPP-IV activity was decreased and LAP activity was increased in UD patients suggests the potential value for testing the levels of these enzymes for improved classification of patients. In addition, the changes in these enzymes, suggests that the proteolytic maturation of their proneuropeptide and prohormone subtrates may also be affected in UD, resulting in altered production of the associated bioactive peptides. 相似文献959.
Lili Sahakyan Tina Meller Ulrika Evermann Simon Schmitt Julia-Katharina Pfarr Jens Sommer Thomas R Kwapil Igor Nenadi 《Schizophrenia bulletin》2021,47(1):207
Numerous studies have implicated involvement of the hippocampus in the etiology and expression of schizophrenia-spectrum psychopathology, and reduced hippocampal volume is one of the most robust brain abnormalities reported in schizophrenia. Recent studies indicate that early stages of schizophrenia are specifically characterized by reductions in anterior hippocampal volume; however, studies have not examined hippocampal volume reductions in subclinical schizotypy. The present study was the first to examine the associations of positive, negative, and disorganized schizotypy dimensions with hippocampal subfield volumes in a large sample (n = 195) of nonclinically ascertained young adults, phenotyped using the Multidimensional Schizotypy Scale (MSS). Hippocampal subfields were analyzed from high-resolution 3 Tesla structural magnetic resonance imaging scans testing anatomical models, including anterior vs posterior regions and the cornu ammonis (CA), dentate gyrus (DG), and subiculum subfields separately for the left and right hemispheres. We demonstrate differential spatial effects across anterior vs posterior hippocampus segments across different dimensions of the schizotypy risk phenotype. The interaction of negative and disorganized schizotypy robustly predicted left hemisphere volumetric reductions for the anterior and total hippocampus, and anterior CA and DG, and the largest reductions were seen in participants high in negative and disorganized schizotypy. These findings extend previous early psychosis studies and together with behavioral studies of hippocampal-related memory impairments provide the basis for a dimensional neurobiological hippocampal model of schizophrenia risk. Subtle hippocampal subfield volume reductions may be prevalent prior to the onset of detectable prodromal clinical symptoms of psychosis and play a role in the etiology and development of such conditions. 相似文献
960.
Mustapha Itani Sandra Sif Gylfadottir Thomas Krigrd Alexander Gramm Kristensen Diana Hedevang Christensen Pall Karlsson Sren Mller Henning Andersen Hatice Tankisi Jens Steen Nielsen Troels Staehelin Jensen Reimar Wernich Thomsen Nanna Brix Finnerup Sren Hein Sindrup 《Journal of the peripheral nervous system : JPNS》2021,26(1):55-65
Diabetic polyneuropathy (DPN) can be classified based on fiber diameter into three subtypes: small fiber neuropathy (SFN), large fiber neuropathy (LFN), and mixed fiber neuropathy (MFN). We examined the effect of different diagnostic models on the frequency of polyneuropathy subtypes in type 2 diabetes patients with DPN. This study was based on patients from the Danish Center for Strategic Research in Type 2 Diabetes cohort. We defined DPN as probable or definite DPN according to the Toronto Consensus Criteria. DPN was then subtyped according to four distinct diagnostic models. A total of 277 diabetes patients (214 with DPN and 63 with no DPN) were included in the study. We found a considerable variation in polyneuropathy subtypes by applying different diagnostic models independent of the degree of certainty of DPN diagnosis. For probable and definite DPN, the frequency of subtypes across diagnostic models varied from: 1.4% to 13.1% for SFN, 9.3% to 21.5% for LFN, 51.4% to 83.2% for MFN, and 0.5% to 14.5% for non‐classifiable neuropathy (NCN). For the definite DPN group, the frequency of subtypes varied from: 1.6% to 13.5% for SFN, 5.6% to 20.6% for LFN, 61.9% to 89.7% for MFN, and 0.0% to 6.3% for NCN. The frequency of polyneuropathy subtypes depends on the type and number of criteria applied in a diagnostic model. Future consensus criteria should clearly define sensory functions to be tested, methods of testing, and how findings should be interpreted for both clinical practice and research purpose. 相似文献