全文获取类型
收费全文 | 5656篇 |
免费 | 255篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 33篇 |
儿科学 | 240篇 |
妇产科学 | 78篇 |
基础医学 | 524篇 |
口腔科学 | 107篇 |
临床医学 | 416篇 |
内科学 | 1248篇 |
皮肤病学 | 179篇 |
神经病学 | 413篇 |
特种医学 | 184篇 |
外科学 | 984篇 |
综合类 | 109篇 |
预防医学 | 235篇 |
眼科学 | 264篇 |
药学 | 498篇 |
中国医学 | 36篇 |
肿瘤学 | 383篇 |
出版年
2024年 | 1篇 |
2023年 | 28篇 |
2022年 | 80篇 |
2021年 | 212篇 |
2020年 | 106篇 |
2019年 | 144篇 |
2018年 | 166篇 |
2017年 | 119篇 |
2016年 | 168篇 |
2015年 | 186篇 |
2014年 | 274篇 |
2013年 | 368篇 |
2012年 | 524篇 |
2011年 | 521篇 |
2010年 | 278篇 |
2009年 | 244篇 |
2008年 | 389篇 |
2007年 | 405篇 |
2006年 | 376篇 |
2005年 | 322篇 |
2004年 | 315篇 |
2003年 | 232篇 |
2002年 | 180篇 |
2001年 | 37篇 |
2000年 | 36篇 |
1999年 | 34篇 |
1998年 | 26篇 |
1997年 | 27篇 |
1996年 | 19篇 |
1995年 | 19篇 |
1994年 | 16篇 |
1993年 | 19篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 13篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有5931条查询结果,搜索用时 15 毫秒
81.
Zaid Ammari Ali A. Hasnie Mohammed Ruzieh Osama Dasa Mohammad Al-Sarie Pinang Shastri Nikita Ashcherkin Pamela S Brewster Christopher J. Cooper Rajesh Gupta 《The American journal of the medical sciences》2021,361(4):445-450
BackgroundComputed Tomography (CT) Pulmonary Angiography is the most commonly used diagnostic study for acute pulmonary embolism (PE). Echocardiogram (ECHO) is also used for risk stratification in acute PE, however the diagnostic performance of CT versus ECHO for risk stratification remains unclear.MethodsCT and ECHO right ventricle (RV) and left ventricle (LV) diameters were measured in a retrospective cohort of patients with acute PE. RV:LV diameter ratios were calculated and correlation between CT and ECHO RV:LV ratio was assessed. Sensitivity and specificity for the composite adverse events endpoint of mortality, respiratory failure requiring intubation, cardiac arrest, or shock requiring vasopressors within 30 days of admission were assessed for CT or ECHO derived RV:LV ratio alone and in combination with biomarkers (troponin or B-type natriuretic peptide).ResultsA total of 74 subjects met the inclusion criteria and had a mean age of 62±18 years. The proportion of patients with RV:LV >1 was similar when comparing CT (37.8%) versus ECHO (33.8%) (P = 0.61). A statistically significant correlation was found between CT derived and ECHO derived RV:LV diameter ratio (r = 0.832, P < 0.001). The sensitivity and specificity to predict 30-day composite adverse events for CT versus ECHO derived RV:LV diameter ratio >1 together with positive biomarker status was similar with sensitivity and specificity of 87% and 41% versus 87% and 42%, respectively.ConclusionsIn patients with acute PE, CT and ECHO RV:LV diameter ratio correlate well and identify similar proportion of PE patients at risk for early adverse events. These findings may streamline risk stratification of patients with acute PE. 相似文献
82.
83.
84.
85.
Rajendra Kumar Gokhroo Kaul Anushri M.T. Tarik C. Kailash N. Rajesh K. Ashish G. Manish C. Subhash 《Indian heart journal》2021,73(2):205-210
BackgroundSacubitril/Valsartan (ARNI) has now class 1 recommendation for treatment of heart failure with reduced ejection fraction (HFrEF). It has been shown to reduce cardiovascular morbidity & mortality in Heart failure with reduced ejection fraction (HFrEF) and significant improvement in all echocardiographic parameters besides TEI index. Tei index is a marker of inflammation, myocardial cell metabolism and its contractile function has not been evaluated as a distinctive entity so we took up this study to evaluate the effects of ARNI on the LV functions using two dimensional (2D)ECHO parameters in Indian population and to assess TEI index for myocardial function.Methods256 patients with class II, III or IV HF and EF<40% were enrolled. 171(66.8%) were males and 85(33.2%) were females. Patients were evaluated at baseline, 6 and 12 months for LVEF, LV mass &,LVMPI. Drug was discontinued in 2 patients due to angioedema, in 5 patients due to acute kidney injury and in 2 patients due to hypotension. LV mass measurement done by linear echocardiographic method and Flow Doppler method used for TEI index calculation.ResultsBaseline parameters in 247 patients were mean EF = 26.33 ± 6.28%, mean LV mass = 270.84 ± 68.94 gm, mean Tei Index = 0.852 ± 0.22. ARNI use was associated with an average gradual increase in EF, from a mean baseline of 26.33 ± 6.28% to 33.88 ± 7.73%(p = 0.000001) after 1 year of treatment. There was a significant progressive reduction of 57.97 g/m2 in mean LV mass index after 1 year of treatment (p = 0.000001).TEI index showed significant reduction from baseline mean 0.85 ± 0.22 to 0.70 ± 0.12(p = 0.000001)after 1 year of treatment.ConclusionUse of ARNI as additive adjunct to standard care of treatment resulted in significant progressive decline in LV mass and increase in TEI index. 相似文献
86.
Ahlawat SK 《JOP : Journal of the pancreas》2008,9(2):230-234
Lymphoepithelial cysts of the pancreas are extremely rare, benign, nonneoplastic cysts that may simulate pseudocysts or cystic neoplasm of the pancreas. Endosonographic and cytologic features of pancreatic lymphoepithelial cysts are poorly characterized because of their rarity. However, appropriate prospective diagnosis of pancreatic lymphoepithelial cysts using endoscopic ultrasound-guided fined needle aspiration (EUS-FNA) cytology may permit conservative management because of their benign nature. We conducted a MEDLINE search using the MeSH terms "pancreas", "cyst" and identified 16 patients who were diagnosed with endosonography or computerized tomography (CT) guided fine needle aspiration. Usefulness and pitfalls of EUS- or CT-guided cyst fluid analysis in the pre-operative diagnosis of pancreatic lymphoepithelial cysts are discussed. 相似文献
87.
Mohammad Alkhalil Alessandra Borlotti Giovanni Luigi De Maria Lisa Gaughran Jeremy Langrish Andrew Lucking Vanessa Ferreira Rajesh K. Kharbanda Adrian P. Banning Keith M. Channon Erica Dall’Armellina Robin P. Choudhury 《Journal of cardiovascular magnetic resonance》2018,20(1):82
Background
It has recently been suggested that myocardial oedema follows a bimodal pattern early post ST-segment elevation myocardial infarction (STEMI). Yet, water content, quantified using tissue desiccation, did not return to normal values unlike oedema quantified by cardiovascular magnetic resonance (CMR) imaging. We studied the temporal changes in the extent and intensity of injured myocardium using T1-mapping technique within the first week after STEMI.Methods
A first group (n?=?31) underwent 3 acute 3?T CMR scans (time-point (TP) <?3?h, 24?h and 6?days), including cine, native shortened modified look-locker inversion recovery T1 mapping, T2* mapping and late gadolinium enhancement (LGE). A second group (n?=?17) had a single scan at 24?h with an additional T2-weighted sequence to assess the difference in the extent of area-at-risk (AAR) compared to T1-mapping.Results
The mean T1 relaxation time value within the AAR of the first group was reduced after 24?h (P?<?0.001 for TP1 vs.TP2) and subsequently increased at 6?days (P?=?0.041 for TP2 vs.TP3). However, the extent of AAR quantified using T1-mapping did not follow the same course, and no change was detected between TP1&TP2 (P?=?1.0) but was between TP2 &TP3 (P?=?0.019). In the second group, the extent of AAR was significantly larger on T1-mapping compared to T2-weighted (42?±?15% vs. 39?±?15%, P?=?0.025). No change in LGE was detected while microvascular obstruction and intra-myocardial haemorrhage peaked at different time points within the first week of reperfusion.Conclusion
The intensity of oedema post-STEMI followed a bimodal pattern; while the extent of AAR did not track the same course. This discrepancy has implications for use of CMR in this context and may explain the previously reported disagreement between oedema quantified by imaging and tissue desiccation.88.
89.
K. Vinodraj I. M. Nagendra Nayak J. Vikram Rao Paul Mathai N. Chandralekha B. Nitasha D. Rajesh T. K. Chethan 《Indian journal of pharmacology》2015,47(2):181-184
Objectives:To evaluate the efficacy of liraglutide with pioglitazone for prevention of dexamethasone induced hepatic steatosis, dyslipidemia and hyperglycemia in Albino rats.Results:Dexamethasone caused hepatomegaly, dyslipidemia, and hyperglycemia. Both pioglitazone and liraglutide significantly reduced hepatomegaly, dyslipidemia and hyperglycemia (P < 0.01). Reduction of blood sugar levels after glucose load was significant with pioglitazone when compared with liraglutide (P < 0.01).Conclusion:Liraglutide has comparable efficacy to pioglitazone in prevention of dexamethasone induced hepatomegaly, dyslipidemia and fasting hyperglycemia.KEY WORDS: Dexamethasone, hepatomegaly, hyperglycemia, liraglutide, pioglitazone, prevention 相似文献
90.
Sandeep Chaudhary Bharti Rajesh K. Shyamlal Lalit Yadav Mohit K. Tiwari Krishan Kumar 《RSC advances》2018,8(41):23152
Herein, we disclose the first example of an efficient, silver oxide nanoparticle-catalyzed, direct regioselective synthesis of 3-ylidenephthalides 11–16 and isocoumarins 17–20via sonogashira type coupling followed by substrate-controlled 5-exo-dig or 6-endo-dig cyclization reaction, respectively. This one pot coupling involves reaction of substituted 2-halobenzoic acid with meta/para-substituted and ortho-substituted terminal alkynes, which proceeded in a regioselective manner resulting in the formation of 3-ylidenephthalides or isocoumarins, respectively, in excellent yields (up to 95%) with complete Z-selectivity. This protocol features relatively broad substrate scope, mild conditions, operational simplicity, and is favourable with aromatic/alicyclic terminal alkynes. The competition experiments and gram-scale synthesis further highlight the importance and versatility of the methodology. The proposed mechanistic pathways illustrate that the regioselectivity is substantially being controlled by the substituent(s) present on the acetylenic phenyl ring.We report the first example of an efficient, Ag2O nanoparticle-catalyzed, direct regioselective synthesis of 3-ylidenephthalides and isocoumarins via Sonogashira type coupling followed by substrate-controlled 5-exo-dig or 6-endo-dig cyclization reaction, respectively. 相似文献