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   2512篇
  免费   156篇
  国内免费   18篇
耳鼻咽喉   7篇
儿科学   44篇
妇产科学   34篇
基础医学   271篇
口腔科学   51篇
临床医学   170篇
内科学   623篇
皮肤病学   25篇
神经病学   252篇
特种医学   122篇
外科学   336篇
综合类   3篇
预防医学   240篇
眼科学   52篇
药学   168篇
中国医学   8篇
肿瘤学   280篇
  2024年   6篇
  2023年   43篇
  2022年   99篇
  2021年   179篇
  2020年   87篇
  2019年   113篇
  2018年   112篇
  2017年   91篇
  2016年   94篇
  2015年   121篇
  2014年   110篇
  2013年   147篇
  2012年   198篇
  2011年   181篇
  2010年   107篇
  2009年   103篇
  2008年   131篇
  2007年   137篇
  2006年   118篇
  2005年   88篇
  2004年   100篇
  2003年   61篇
  2002年   58篇
  2001年   21篇
  2000年   20篇
  1999年   19篇
  1998年   17篇
  1997年   3篇
  1996年   9篇
  1995年   7篇
  1994年   2篇
  1993年   8篇
  1992年   19篇
  1991年   8篇
  1990年   6篇
  1989年   9篇
  1988年   9篇
  1987年   4篇
  1986年   3篇
  1985年   8篇
  1984年   2篇
  1977年   2篇
  1976年   3篇
  1974年   1篇
  1973年   3篇
  1972年   4篇
  1971年   3篇
  1970年   1篇
  1969年   4篇
  1968年   4篇
排序方式: 共有2686条查询结果,搜索用时 0 毫秒
81.
Journal of Interventional Cardiac Electrophysiology - The purpose of the study was to evaluate the impact of left atrial posterior wall isolation (LAPWI) in addition to pulmonary vein isolation...  相似文献   
82.
83.
This paper demonstrates the use of peridynamics and discrete multiphysics to assess micro crack formation and propagation in asphalt at low temperatures and under freezing conditions. Three scenarios are investigated: (a) asphalt without air voids under compressive load, (b) asphalt with air voids and (c) voids filled with freezing water. The first two are computed with Peridynamics, the third with peridynamics combined with discrete multiphysics. The results show that the presence of voids changes the way cracks propagate in the material. In asphalt without voids, cracks tend to propagate at the interface between the mastic and the aggregate. In the presence of voids, they ‘jump’ from one void to the closest void. Water expansion is modelled by coupling Peridynamics with repulsive forces in the context of Discrete Multiphysics. Freezing water expands against the voids’ internal surface, building tension in the material. A network of cracks forms in the asphalt, weakening its mechanical properties. The proposed methodology provides a computational tool for generating samples of ‘digital asphalt’ that can be tested to assess the asphalt properties under different operating conditions.  相似文献   
84.
Many different osteotomy procedures has been proposed in the literature for dental implant site preparation. The osseodensification is a drilling technique that has been proposed to improve the local bone quality and implant stability in poor density alveolar ridges. This technique determines an expansion of the implant site by increasing the density of the adjacent bone. The aim of the present investigation was to evaluate the effectiveness of the osseodensification technique for implant site preparation through a literature review and meta-analysis. The database electronic research was performed on PubMed (Medline) database for the screening of the scientific papers. A total of 16 articles have been identified suitable for the review and qualitative analysis—11 clinical studies (eight on animals, three on human subjects), four literature reviews, and one case report. The meta-analysis was performed to compare the bone-to-implant contact % (BIC), bone area fraction occupied % (BAFO), and insertion torque of clockwise and counter-clockwise osseodensification procedure in animal studies. The included articles reported a significant increase in the insertion torque of the implants positioned through the osseodensification protocol compared to the conventional drilling technique. Advantages of this new technique are important above all when the patient has a strong missing and/or low quantity of bone tissue. The data collected until the drafting of this paper detect an improvement when the osseodensification has been adopted if compared to the conventional technique. A significant difference in BIC and insertion torque between the clockwise and counter-clockwise osseodensification procedure was reported, with no difference in BAFO measurements between the two approaches. The effectiveness of the present study demonstrated that the osseodensification drilling protocol is a useful technique to obtain increased implant insertion torque and bone to implant contact (BIC) in vivo. Further randomized clinical studies are required to confirm these pieces of evidence in human studies.  相似文献   
85.
86.
The emergence of resistance to imatinib (IM) mediated by mutations in the BCR-ABL domain has become a major challenge in the treatment of chronic myeloid leukemia (CML). Here, we report on studies performed with a novel small molecule inhibitor, PHA-739358, which selectively targets Bcr-Abl and Aurora kinases A to C. PHA-739358 exhibits strong antiproliferative and proapoptotic activity against a broad panel of human BCR-ABL-positive and -negative cell lines and against murine BaF3 cells ectopically expressing wild-type (wt) or IM-resistant BCR-ABL mutants, including T315I. Pharmacologic synergism of IM and PHA-739358 was observed in leukemia cell lines with subtotal resistance to IM. Treatment with PHA-739358 significantly decreased phosphorylation of histone H3, a marker of Aurora B activity and of CrkL, a downstream target of Bcr-Abl, suggesting that PHA-739358 acts via combined inhibition of Bcr-Abl and Aurora kinases. Moreover, strong antiproliferative effects of PHA-739358 were observed in CD34(+) cells derived from untreated CML patients and from IM-resistant individuals in chronic phase or blast crisis, including those harboring the T315I mutation. Thus, PHA-739358 represents a promising new strategy for treatment of IM-resistant BCR-ABL-positive leukemias, including those harboring the T315I mutation. Clinical trials investigating this compound in IM-resistant CML have recently been initiated.  相似文献   
87.
Social polarization refers to the measurement of the distance between different social groups, defined on the basis of variables such as race, religion, or ethnicity. We propose two approaches to measuring social polarization in the case where the distance between groups is based on an ordinal variable, such as self-assessed health status. The first one, the ‘stratification approach’, amounts to assessing the degree of non-overlapping of the distributions of the ordinal variable between the different population subgroups that are distinguished. The second one, the ‘antipodal approach’, considers that the social polarization of an ordinal variable will be maximal if the individuals belonging to a given population subgroup are in the same health category, this category corresponding either to the lowest or to the highest health status. An empirical illustration is provided using the 2009 cross-sectional data of the European Union Statistics on Income and Living Conditions (EU-SILC). We find that Estonia, Latvia, and Ireland have the highest degree of social polarization when the ordinal variable under scrutiny refers to self-assessed health status and the (unordered) population subgroups to the citizenship of the respondent whereas Luxembourg is the country with the lowest degree of social polarization in health.  相似文献   
88.
89.
The treatment of premenstrual dysphoric disorder (PMDD) is far from satisfactory, as there is a high proportion of patients who do not respond to conventional treatment. The antidiuretic sulfonamide, acetazolamide, inhibits carbonic anhydrase and potentiates GABAergic transmission; the latter is putatively involved in PMDD. We therefore tried acetazolamide in a series of women with intractable PMDD. Here, we describe a series of eight women diagnosed with DSM-IV-TR PMDD, five of whom had comorbidity with a mood disorder and one with an anxiety disorder, who were resistant to treatment and responded with symptom disappearance after being added-on 125 mg/day acetazolamide for 7-10 days prior to menses each month. Patients were free from premenstrual symptoms at the 12-month follow-up. We suggest that acetazolamide may be used to improve symptoms of PMDD in cases not responding to other treatments. GABAergic mechanisms may be involved in counteracting PMDD symptoms.  相似文献   
90.
Erythrocyte glutathione transferase (e-GST) displays increased activity in patients with renal damage and positive correlation with homocysteine (Hcy) in patients under maintenance hemodialysis. Here, we determined e-GST, Hcy, and erythrocyte catalase (e-CAT) in 328 patients affected by type 2 diabetes mellitus (T2DM), 61 diabetic non-nephropathic patients and 267 affected by diabetes and by chronic kidney disease (CKD) under conservative therapy subdivided into four stages according to K-DOQI lines. e-GST activity was significantly higher in all T2DM patients compared to the control group (7.90 ± 0.26 vs. 5.6 ± 0.4 U/gHb), and we observed an enhanced activity in all subgroups of CKD diabetic patients. No significant correlation or increase has been found for e-CAT in all patients tested. Mean Hcy in diabetic patients is higher than that in healthy subjects (33.42 ± 1.23 vs. 13.6 ± 0.8 μM), and Hcy increases in relation to the CKD stage. As expected, a significant correlation was found between e-GST and Hcy levels. These findings suggest that e-GST hyperactivity is not caused directly by diabetes but by its consequent renal damage. e-GST, as well as Hcy, may represent an early biomarker of renal failure.  相似文献   
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