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   117567篇
  免费   31558篇
  国内免费   1130篇
耳鼻咽喉   2570篇
儿科学   3108篇
妇产科学   2660篇
基础医学   5717篇
口腔科学   5310篇
临床医学   27821篇
内科学   29620篇
皮肤病学   3850篇
神经病学   13835篇
特种医学   4232篇
外国民族医学   3篇
外科学   20922篇
综合类   364篇
现状与发展   40篇
一般理论   28篇
预防医学   14841篇
眼科学   2534篇
药学   2402篇
  1篇
中国医学   61篇
肿瘤学   10336篇
  2024年   545篇
  2023年   5039篇
  2022年   1160篇
  2021年   2915篇
  2020年   5426篇
  2019年   2242篇
  2018年   7134篇
  2017年   7483篇
  2016年   8109篇
  2015年   8236篇
  2014年   10806篇
  2013年   12756篇
  2012年   4751篇
  2011年   4647篇
  2010年   7487篇
  2009年   9799篇
  2008年   4612篇
  2007年   3711篇
  2006年   4893篇
  2005年   3552篇
  2004年   2821篇
  2003年   2455篇
  2002年   2374篇
  2001年   2167篇
  2000年   1430篇
  1999年   2024篇
  1998年   2397篇
  1997年   2197篇
  1996年   2206篇
  1995年   1929篇
  1994年   1313篇
  1993年   1120篇
  1992年   1031篇
  1991年   908篇
  1990年   755篇
  1989年   749篇
  1988年   705篇
  1987年   576篇
  1986年   568篇
  1985年   502篇
  1984年   449篇
  1983年   490篇
  1982年   439篇
  1981年   418篇
  1980年   298篇
  1979年   199篇
  1978年   252篇
  1977年   251篇
  1976年   194篇
  1974年   171篇
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
51.
52.

Background

Limited data exists demonstrating the efficacy of minimally invasive surgery (MIS) compared to median sternotomy (MS) for multiple valvular disease (MVD). This systematic review and meta-analysis aims to compare operative and peri-operative outcomes of MIS vs MS in MVD.

Methods

PubMed, Ovid, and Embase were searched from inception until August 2019 for randomized and observational studies comparing MIS and MS in patients with MVD. Clinical outcomes of intra- and postoperative times, reoperation for bleeding and surgical site infection were evaluated.

Results

Five observational studies comparing 340 MIS vs 414 MS patients were eligible for qualitative and quantitative review. The quality of evidence assessed using the Newcastle-Ottawa scale was good for all included studies. Meta-analysis demonstrated increased cardiopulmonary bypass time for MIS patients (weighted mean difference [WMD], 0.487; 95% confidence interval [CI], 0.365-0.608; P < .0001). Similarly, aortic cross-clamp time was longer in patients undergoing MIS (WMD, 0.632; 95% CI, 0.509-0.755; P < .0001). No differences were found in operative mortality, reoperation for bleeding, surgical site infection, or hospital stay.

Conclusions

MIS for MVD have similar short-term outcomes compared to MS. This adds value to the use of minimally invasive methods for multivalvular surgery, despite conferring longer operative times. However, the paucity in literature and learning curve associated with MIS warrants further evidence, ideally randomized control trials, to support these findings.
  相似文献   
53.
54.
55.
56.
57.
58.
Breast elastography has been available for more than 15 years but is not widely incorporated into clinical practice. Many publications report extremely high accuracy for various breast elastographic techniques. However, results in the literature are extremely variable. This variability is most likely due to variations in technique, a relatively steep learning curve, and variability in methods between vendors. This article describes our protocol for performing breast elastography using both strain elastography and shear wave elastography, which produces high sensitivity and specificity. Additionally, we will describe the most commonly known false-positive and false-negative lesions as well as how to detect them.  相似文献   
59.
The midwifery art has emphasised the uniqueness of human beings throughout its Nordic history. The educated Nordic midwife has in the last decade celebrated several hundred years of memories. This article studies how the key ideas of the midwifery art and patterns of ideas become evident in the zeitgeist from the beginning of the 19th century to the millennium in the Nordic countries. The legacy and pattern of ideas of the art of midwifery are interpreted in relation to the texts of the selected historical sources and based on Ricoeur's phenomenological-hermeneutic approach to the text and further to the dedication of understanding and interpretation. The historical sources refer to unprinted primary sources from historical archives and printed secondary and tertiary sources. The patterns of ideas include a tripartite whole: the true cultivation of the head, the philosophy and aesthetics of the hand, the strength of the heart and the drive of calling. These ideas open for unique visions and attest to the evident in modern midwives. Today's midwives have academic training with examinations, and the education is based on scientific evidence. The midwife profession is authorised by the state and supervised by the authorities.  相似文献   
60.
Ovarian carcinoma is one of the most lethal malignancies, but only very few prognostic biomarkers are known. The degradome, comprising proteases, protease non-proteolytic homologues and inhibitors, have been involved in the prognosis of many cancer types, including ovarian carcinoma. The prognostic significance of the whole degradome family has not been specifically studied in high-grade serous ovarian cancer. A targeted DNA microarray known as the CLIP-CHIP microarray was used to identify potential prognostic factors in ten high-grade serous ovarian cancer women who had early recurrence (<1.6 years) or late/no recurrence after first line surgery and chemotherapy. In women with early recurrence, we identified seven upregulated genes (TMPRSS4, MASP1/3, SPC18, PSMB1, IGFBP2, CFI – encoding Complement Factor I – and MMP9) and one down-regulated gene (ADAM-10). Using immunohistochemistry, we evaluated the prognostic effect of these 8 candidate genes in an independent cohort of 112 high-grade serous ovarian cancer women. Outcomes were progression, defined according to CA-125 criteria, and death. Multivariate Cox proportional hazard regression models were done to estimate the associations between each protein and each outcome. High ADAM-10 expression (intensity of 2–3) was associated with a lower risk of progression (adjusted hazard ratio (HR): 0.51; 95% confidence interval (CI): 0.29-0.87). High complement factor I expression (intensity 2–3) was associated with a higher risk of progression (adjusted HR: 2.30, 95% CI: 1.17–4.53) and death (adjusted HR: 3.42; 95% CI: 1.72–6.79). Overall, we identified the prognostic value of two proteases, ADAM-10 and complement factor I, for high-grade serous ovarian cancer which could have clinical significance.  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