全文获取类型
收费全文 | 3957篇 |
免费 | 190篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 83篇 |
儿科学 | 237篇 |
妇产科学 | 48篇 |
基础医学 | 391篇 |
口腔科学 | 86篇 |
临床医学 | 280篇 |
内科学 | 695篇 |
皮肤病学 | 32篇 |
神经病学 | 298篇 |
特种医学 | 185篇 |
外科学 | 774篇 |
综合类 | 118篇 |
一般理论 | 1篇 |
预防医学 | 186篇 |
眼科学 | 242篇 |
药学 | 264篇 |
中国医学 | 18篇 |
肿瘤学 | 218篇 |
出版年
2023年 | 28篇 |
2022年 | 69篇 |
2021年 | 139篇 |
2020年 | 53篇 |
2019年 | 89篇 |
2018年 | 126篇 |
2017年 | 91篇 |
2016年 | 113篇 |
2015年 | 121篇 |
2014年 | 147篇 |
2013年 | 213篇 |
2012年 | 300篇 |
2011年 | 319篇 |
2010年 | 185篇 |
2009年 | 174篇 |
2008年 | 242篇 |
2007年 | 235篇 |
2006年 | 211篇 |
2005年 | 206篇 |
2004年 | 165篇 |
2003年 | 145篇 |
2002年 | 157篇 |
2001年 | 78篇 |
2000年 | 48篇 |
1999年 | 55篇 |
1998年 | 28篇 |
1997年 | 20篇 |
1996年 | 20篇 |
1995年 | 10篇 |
1993年 | 15篇 |
1992年 | 22篇 |
1991年 | 32篇 |
1990年 | 28篇 |
1989年 | 35篇 |
1988年 | 19篇 |
1987年 | 27篇 |
1986年 | 17篇 |
1985年 | 12篇 |
1984年 | 10篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1981年 | 19篇 |
1979年 | 9篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1975年 | 8篇 |
1974年 | 7篇 |
1973年 | 11篇 |
1971年 | 9篇 |
1969年 | 8篇 |
排序方式: 共有4156条查询结果,搜索用时 15 毫秒
51.
Joachim G. Eichhorn MD Frederick R. Long MD Claudia Jourdan MD Johannes T. Heverhagen MD PhD Sharon L. Hill ARNP Subha V. Raman MD John P. Cheatham MD 《Catheterization and cardiovascular interventions》2008,72(4):544-551
Objective : To evaluate varying CT settings to visualize pediatric vascular stents in comparison to digital angiography (DA). Background : There is a great clinical interest in substituting noninvasive methods to follow up children with congenital heart disease after interventional treatment. Materials and Methods : CT studies in small children with transcatheter placed stents were reviewed, retrospectively. Furthermore, eight stents were implanted in tubes and partially obstructed. CT exams were performed on varying scanners (4 up to 64 slices) with corresponding tube settings. The effects of dose on image quality were evaluated regarding stent size, strut thickness, and in‐stent stenoses in comparison to DA. Results : Fourteen children with 28 implanted stents were identified. Significant differences between higher and lower radiation settings were not found, corresponding with the phantom, where moderate tube setting showed the best results. In vitro, there was an improvement with increasing number of detector rows, which resulted in a decrease of stent strut overestimation (295% down to 201%; P < 0.0001) and a better agreement with DA measurements for mild (78% up to 91%; P = 0.003) and moderate in‐stent stenoses (80% up to 99%; P = 0.0001). Conclusion : Higher radiation exposure settings did not improve image quality, suggesting that the exams could be performed at a lower radiation dose. © 2008 Wiley‐Liss, Inc. 相似文献
52.
We report B.R.B., a bilingual Turkish–English speaker with deep dysphasia. B.R.B. shows the typical pattern of semantic errors in repetition with effects of lexicality and imageability on performance in both languages. The question we asked is whether language type (Turkish or English) or language status—that is, first acquired (L1) or second acquired (L2)—has a greater impact on performance. Results showed that repetition in L1 (Turkish) was better than that in L2 (English). We also observed effects of language status on oral reading, writing to dictation, and naming (spoken and written) with greater impairment to repetition than other tasks in both languages. An additional finding was that spoken-word translation in both directions was worse than written-word translation, and word class had an effect on translation from L1 to L2. We argue that interactive activation models of deep dysphasia could explain deep dysphasia in bilingual speakers and interactions between task and language, if the weighted connections that support language processing in L2 are assumed to be weaker, thus causing rapid phonological decay to have more impact on task performance in L2. Implications of the results for models of bilingual language processing are also considered. 相似文献
53.
Henry W. Murray Yunhua Zhang Yan Zhang Vanitha S. Raman Steven G. Reed Xiaojing Ma 《Infection and immunity》2013,81(7):2318-2326
In livers of susceptible but self-curing C57BL/6 mice, intracellular Leishmania donovani infection enhanced Toll-like receptor 4 (TLR4) and TLR2 gene expression. In the liver, infected TLR4−/− mice showed reduced gamma interferon (IFN-γ), tumor necrosis factor (TNF), and inducible nitric oxide synthase (iNOS) mRNA expression, higher-level and slowly resolving infection, delayed granuloma formation, and little response to low-dose chemotherapy; in serum, the ratio of IFN-γ to interleukin 10 (IL-10) activity was decreased by 50%. In contrast, in TLR2−/− mice, control of liver infection, parasite killing, and granuloma assembly were accelerated and chemotherapy''s efficacy enhanced. In livers of infected TLR2−/− mice, mRNA expression was not increased for inflammatory cytokines or iNOS or decreased for IL-10; however, the serum IFN-γ/IL-10 ratio was increased 6.5-fold and minimal responses to IL-10 receptor blockade suggested downregulated IL-10. In established infection in wild-type mice, blockading TLR2 induced parasite killing and triggering TLR4 strengthened resistance and promoted chemotherapy''s effect. Thus, in experimental L. donovani infection in the liver, TLR4 signaling upregulates and TLR2 signaling downregulates macrophage antileishmanial activity, making both receptors potential therapeutic targets in visceral leishmaniasis for engagement (TLR4) or blockade (TLR2). 相似文献
54.
Bo Zhang Yan Zhou Nan Lin Rebecca F. Lowdon Chibo Hong Raman P. Nagarajan Jeffrey B. Cheng Daofeng Li Michael Stevens Hyung Joo Lee Xiaoyun Xing Jia Zhou Vasavi Sundaram GiNell Elliott Junchen Gu Taoping Shi Philippe Gascard Mahvash Sigaroudinia Thea D. Tlsty Theresa Kadlecek Arthur Weiss Henriette O’Geen Peggy J. Farnham Cécile L. Maire Keith L. Ligon Pamela A.F. Madden Angela Tam Richard Moore Martin Hirst Marco A. Marra Baoxue Zhang Joseph F. Costello Ting Wang 《Genome research》2013,23(9):1522-1540
55.
Subramaniam Puvaneswary Hanumantha Rao Balaji Raghavendran Nurul Syuhada Ibrahim Malliga Raman Murali Azhar Mahmood Merican T. Kamarul 《International journal of medical sciences》2013,10(12):1608-1614
The objective of this study was to compare the morphological and chemical composition of bone graft (BG) and coral graft (CG) as well as their osteogenic differentiation potential using rabbit mesenchymal stem cells (rMSCs) in vitro. SEM analysis of BG and CG revealed that the pores in these grafts were interconnected, and their micro-CT confirmed pore sizes in the range of 107-315 µm and 103-514 µm with a total porosity of 92% and 94%, respectively. EDS analysis indicated that the level of calcium in CG was relatively higher than that in BG. FTIR of BG and CG confirmed the presence of functional groups corresponding to carbonyl, aromatic, alkyl, and alkane groups. XRD results revealed that the phase content of the inorganic layer comprised highly crystalline form of calcium carbonate and carbon. Atomic force microscopy analysis showed CG had better surface roughness compared to BG. In addition, significantly higher levels of osteogenic differentiation markers, namely, alkaline phosphatase (ALP), Osteocalcin (OC) levels, and Osteonectin and Runx2, Integrin gene expression were detected in the CG cultures, when compared with those in the BG cultures. In conclusion, our results demonstrate that the osteogenic differentiation of rMSCs is relatively superior in coral graft than in bone graft culture system. 相似文献
56.
57.
58.
Variations in the morphology of pancreas are not very common. We observed a rare variant of the uncinate process of the pancreas that extended in the mesentery of the small intestine. After its origin from the lower part of the head of the pancreas, the mesenteric process (MP) passed over the third part of the duodenum to enter the mesentery of the jejunum and ileum and extended up to the level of the pelvic brim. The branches of the superior mesenteric vessels were embedded in the extended MP of the pancreas. This aberrant extension of the pancreas was drained by a narrow duct, which joined the main pancreatic duct inside the head. We did not observe a separate uncinate process arising from the head. On histology normal acini and endocrine cells were observed in the extension. This variant is important as symptoms of pancreatic disease from such extensions may be confused with other commonly encountered acute or chronic abdominal conditions. 相似文献
59.
Arunaloke Chakrabarti Prashant Sood Shivaprakash M. Rudramurthy Sharon Chen Harsimran Kaur Malini Capoor Deepinder Chhina Ratna Rao Vandana Kalwaje Eshwara Immaculata Xess Anupama J. Kindo P. Umabala Jayanthi Savio Atul Patel Ujjwayini Ray Sangeetha Mohan Ranganathan Iyer Jagdish Chander Anita Arora Raman Sardana Indranil Roy B. Appalaraju Ajanta Sharma Anjali Shetty Neelam Khanna Rungmei Marak Sanjay Biswas Shukla Das B. N. Harish Sangeeta Joshi Deepak Mendiratta 《Intensive care medicine》2015,41(2):285-295
60.
Sankar D. Navaneethan Jesse D. Schold Susana Arrigain Stacey E. Jolly Joseph V. Nally Jr 《Journal of the American Society of Nephrology : JASN》2015,26(10):2512-2520
CKD is associated with higher risk of death, but details regarding differences in cause-specific death in CKD are unclear. We examined the leading causes of death among a non–dialysis-dependent CKD population using an electronic medical record-based CKD registry in a large healthcare system and the Ohio Department of Health mortality files. We included 33,478 white and 5042 black patients with CKD who resided in Ohio between January 2005 and September 2009 and had two measurements of eGFR<60 ml/min per 1.73 m2 obtained 90 days apart. Causes of death (before ESRD) were classified into cardiovascular, malignancy, and non-cardiovascular/non-malignancy diseases and non–disease-related causes. During a median follow-up of 2.3 years, 6661 of 38,520 patients (17%) with CKD died. Cardiovascular diseases (34.7%) and malignant neoplasms (31.8%) were the leading causes of death, with malignancy-related deaths more common among those with earlier stages of kidney disease. After adjusting for covariates, each 5 ml/min per 1.73 m2 decline in eGFR was associated with higher risk of death due to cardiovascular disease (hazard ratio [HR], 1.10; 95% confidence interval [95% CI], 1.08 to 1.12) and non-cardiovascular/non-malignancy diseases (HR, 1.12; 95% CI, 1.09 to 1.14) but not to malignancy. In the adjusted models, blacks had overall-mortality hazard ratios similar to those of whites but higher hazard ratios for cardiovascular deaths. Further studies to confirm these findings and explain the mechanisms for differences are warranted. In addition to lowering cardiovascular burden in CKD, efforts to target known risk factors for cancer at the population level are needed. 相似文献