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   46156篇
  免费   1339篇
  国内免费   205篇
耳鼻咽喉   347篇
儿科学   1787篇
妇产科学   1011篇
基础医学   4950篇
口腔科学   1998篇
临床医学   4089篇
内科学   8404篇
皮肤病学   893篇
神经病学   2528篇
特种医学   868篇
外科学   7119篇
综合类   4122篇
现状与发展   1篇
一般理论   2篇
预防医学   5279篇
眼科学   718篇
药学   2048篇
  138篇
中国医学   397篇
肿瘤学   1001篇
  2024年   185篇
  2023年   389篇
  2022年   573篇
  2021年   1064篇
  2020年   708篇
  2019年   6445篇
  2018年   4861篇
  2017年   2600篇
  2016年   649篇
  2015年   531篇
  2014年   1321篇
  2013年   1375篇
  2012年   1347篇
  2011年   1360篇
  2010年   1073篇
  2009年   1000篇
  2008年   1059篇
  2007年   1040篇
  2006年   786篇
  2005年   519篇
  2004年   405篇
  2003年   296篇
  2002年   236篇
  2001年   190篇
  2000年   181篇
  1999年   118篇
  1998年   77篇
  1997年   73篇
  1996年   78篇
  1995年   75篇
  1994年   77篇
  1993年   42篇
  1992年   48篇
  1991年   44篇
  1990年   36篇
  1989年   30篇
  1988年   40篇
  1985年   1451篇
  1984年   2271篇
  1983年   1583篇
  1982年   1701篇
  1981年   1623篇
  1980年   1402篇
  1979年   1389篇
  1978年   1145篇
  1977年   873篇
  1976年   1023篇
  1975年   838篇
  1974年   748篇
  1973年   685篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.

Background

The purpose of the study was to evaluate the association between fetal echocardiographic measurements and the need for intervention (primary coarctation repair, staged coarctation repair, or catheter intervention) in prenatally diagnosed coarctation of the aorta.

Methods

A single-centre retrospective cohort study (2005-2015) of 107 fetuses diagnosed with suspected coarctation of the aorta in the setting of an apex-forming left ventricle and antegrade flow across the mitral and aortic valves.

Results

Median gestational age at diagnosis was 32 weeks (interquartile range, 23-35 weeks). Fifty-six (52%) did not require any neonatal intervention, 51 patients (48%) underwent a biventricular repair. In univariable analysis, an increase in ascending aorta (AAo) peak Doppler flow velocity (odds ratio [OR], 1.40 [95% confidence interval [CI], 1.05-1.91] per 20 cm/s; P = 0.03) was associated with intervention. No intervention was associated with larger isthmus size (OR, 0.23; P < 0.001), transverse arch diameter (OR, 0.23; P < 0.001), and aortic (OR, 0.72; P = 0.02), mitral (OR, 0.58; P = 0.001), and AAo (OR, 0.53; P < 0.001) z-scores. In multivariable analysis, higher peak AAo Doppler (OR, 2.51 [95% CI, 1.54-4.58] per 20 cm/s; P = 0.001) and younger gestational age at diagnosis (OR, 0.81 [95% CI, 0.70-0.93] per week; P = 0.005) were associated with intervention, whereas a higher AAo z-score (OR, 0.65 [95% CI, 0.43-0.94] per z; P = 0.029) and transverse arch dimension (OR, 0.44 [95% CI, 0.18-0.97]; P = 0.05) decreased the risk of intervention.

Conclusions

In prenatally suspected coarctation, the variables associated with intervention comprised smaller AAo and transverse arch size, earlier gestational age at diagnosis, and the additional finding of a higher peak AAo Doppler.  相似文献   
2.
Nephrolithiasis is a common pathology encountered in the primary care and emergency department (ED) setting. In 2009 alone, there were over one million ED visits related to nephrolithiasis Higa et al. (2017) [1]. Emergent treatment options range from non-invasive pain control and patient education to lithotripsy and other invasive urologic procedures depending on stone location and related pathology. Urethral calculi are estimated to represent 0.3% of all urinary stone diseases Verit et al. (2006) [2]. There are very few case reports documenting distal urethral stone removal in the ED. Here we present a case of distal urethral stone impaction and the removal of this stone by ED providers, leading to expedited care and prevention of consultation and possible admission.  相似文献   
3.

Background

Solid organ transplantation is associated with a higher risk of Epstein-Barr virus (EBV)–related lymphoproliferative disease due to immunosuppressive regimen. Little evidence is currently available on post-transplant lymphoproliferative disorders (PTLDs) in the lung transplant (LuTx) setting, particularly in cystic fibrosis (CF) recipients.

Methods

We retrospectively analyzed all the cases of PTLDs that occurred in our LuTx center between January 2015 and December 2017. We reviewed clinical and radiologic data, donor and recipient EBV serostatus, immunosuppressive therapy, histologic data, and follow-up of these patients.

Results

A total of 77 LuTxs were performed at our center in the study period; 39 (50.6%) patients had CF; 4 developed EBV-related PTLDs. They were all young (17–26 years) CF patients with high serum EBV DNA load. Disease onset was within the first 3 months after LuTx. In 3 cases presentation was associated with fever and infection-like symptoms, whereas in 1 case radiologic suspicion arose unexpectedly from a CT scan performed for different clinical reasons. Diagnosis was reached through lung biopsy in all cases. All patients received rituximab,?cyclophosphamide, doxorubicin hydrochloride (hydroxydaunomycin), vincristine sulfate (Oncovin), and prednisone with variable response and complications.

Conclusion

In our experience, the early development of EBV-related PTLD was a highly aggressive, life-threatening condition, which exclusively affected young CF patients in the early post-transplant period. The rate of this complication was relatively high in our population.Diagnosis with lung biopsy is crucial in all suspected cases and regular monitoring of EBV DNA levels is of utmost importance given the high correlation with PTLDs in patients at increased risk.  相似文献   
4.
5.
6.
AimsOrgan preservation, an important goal in the treatment of head and neck squamous cell carcinoma (HNSCC), may include induction chemotherapy and cisplatin with radiation therapy (CRT). To our knowledge, no reports have directly compared the impact of induction chemotherapy with that of CRT on health-related quality of life (HRQOL).Materials and methodsIn a phase II trial, we assessed the HRQOL of patients treated with induction chemotherapy followed by CRT. Eligible patients had stage III–IV HNSCC. HRQOL questionnaires were administered at baseline, the end of induction (EOI), the end of CRT (EOCRT) and after CRT. Functional Assessment of Cancer Therapy (FACT version 4) assessed HRQOL. We carried out a comparison of changes in HRQOL from baseline to EOI and from EOI to EOCRT. This trial is registered with ClinicalTrials.gov (NCT01566435).ResultsThirty patients were enrolled in the study. Most HRQOL questionnaires were completed (88%). The mean total FACT scores did not differ from baseline to EOI (general: 83.8 versus 79.1, P = 0.08; head and neck: 109.7 versus 105.8, P = 0.33; Total Outcome Index: 69.7 versus 62.3, P = 0.03; respectively, using P ≤ 0.01 to adjust for multiple simultaneous tests of differences). However, total FACT scores significantly worsened from EOI to EOCRT (79.1 versus 62.3, P = 0.01; 105.8 versus 74.2, P < 0.01; 62.3 versus 34.2, P = 0.01; respectively). Within domains, the head and neck cancer subscale score did not differ from baseline to EOI (median 28.5 versus 27.0, P = 0.69), but significantly worsened from EOI to EOCRT (27.0 versus 9.5, P < 0.01). Swallowing, oral pain and voice quality improved from baseline to EOI, but worsened from EOI to EOCRT. Physical and functional scores worsened from baseline to EOI and from EOI to EOCRT. The emotional well-being score improved from baseline to EOI but worsened from EOI to EOCRT.ConclusionsOverall, HRQOL did not significantly change from baseline to EOI but dramatically worsened from EOI to EOCRT.  相似文献   
7.
8.

Background

Liver transplantation from donors after either controlled or uncontrolled cardiac death (DCD) is associated with considerable rates of primary nonfunction (PNF) and ischemic cholangiopathy (IC). Normothermic regional perfusion (NRP) could significantly reduce such rates.

Methods

Retrospective study to analyze short-term (mortality, PNF, vascular complications) and long-term (IC, survival) complications in 11 liver transplants from controlled DCDs using NRP with extracorporeal membrane oxygenation (ECMO) (group 1). They were compared with 51 patients transplanted with grafts from donors after brain death (DBD) (group 2). Mean recipient age, sex, and Model for End-stage Liver Disease (MELD) score were not significantly different.

Results

In group 1, mean functional warm ischemia time was 15.8 (range, 7–40) minutes and 94.1 (range, 20–150) minutes on NRP. The ischemic damage was minimal, as shown by the slight alanine aminotransferase (ALT) and aspartate aminotransferase (AST) rises in the donor serum after 1 hour on NRP and similar rises 24 hours after transplantation in both groups. No patient had IC or acute renal failure. No significant difference was found between the groups for vascular or biliary complications. One group 1 patient had PNF (9.1%), resulting in death. Overall retransplantation and in-hospital death rates were 8.1% and 4.8%, respectively, with no significant difference between groups. Estimated mean survival was 24.6 (95% confidence interval [CI], 20.2–29.1) months in group 1 and 32.3 (95% CI, 30.4–34.2) months in group 2 (not a statistically significant difference).

Conclusion

In our experience, liver transplants from controlled DCDs using NRP with ECMO is associated with a low risk of PNF and IC, with short- and long-term results comparable to those in DBD transplants.  相似文献   
9.
10.
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