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   3560篇
  免费   227篇
  国内免费   15篇
耳鼻咽喉   34篇
儿科学   230篇
妇产科学   78篇
基础医学   431篇
口腔科学   60篇
临床医学   250篇
内科学   624篇
皮肤病学   71篇
神经病学   327篇
特种医学   119篇
外国民族医学   1篇
外科学   551篇
综合类   38篇
预防医学   185篇
眼科学   105篇
药学   323篇
中国医学   4篇
肿瘤学   371篇
  2023年   25篇
  2022年   78篇
  2021年   131篇
  2020年   64篇
  2019年   122篇
  2018年   131篇
  2017年   83篇
  2016年   98篇
  2015年   118篇
  2014年   168篇
  2013年   224篇
  2012年   295篇
  2011年   312篇
  2010年   158篇
  2009年   116篇
  2008年   163篇
  2007年   167篇
  2006年   172篇
  2005年   120篇
  2004年   132篇
  2003年   115篇
  2002年   109篇
  2001年   65篇
  2000年   72篇
  1999年   48篇
  1998年   34篇
  1997年   21篇
  1996年   21篇
  1995年   12篇
  1994年   10篇
  1993年   10篇
  1992年   29篇
  1991年   42篇
  1990年   37篇
  1989年   31篇
  1988年   24篇
  1987年   23篇
  1986年   20篇
  1985年   24篇
  1984年   13篇
  1983年   13篇
  1982年   12篇
  1981年   11篇
  1980年   10篇
  1979年   10篇
  1977年   11篇
  1975年   10篇
  1974年   9篇
  1973年   12篇
  1972年   9篇
排序方式: 共有3802条查询结果,搜索用时 15 毫秒
51.
52.
According to Kyoto protocol carbon sequestration in terrestrial ecosystem is a low cost option to mitigate the increasing atmospheric CO2 concentrations. It has been understood that the world’s forests and their soils have a high potential to sequester the atmospheric carbon. For the last two decades there has been increasing interest among scientists in terrestrial soil carbon storage processes. This review made an attempt to summarize the major chronological advancement of soil organic carbon (SOC) sequestration research and also to underpin the problems yet to be focused on this research at global level. SOC sequestration research began in the early seventies, where most of the studies were estimating the size/stock of the global SOC. In the early eighties, most of the researchers have started to focus on the factors involved in the storage of organic carbon in different ecosystems. Subsequently, the researchers started to work on different types of SOC pools, their size, turnover and chemical characterization in different types of ecosystems. Recently the researcher’s main focus has been the temperature sensitivity of organic carbon in different types of soil and their mechanism of stabilization. There has been interest among researchers on the contribution of microbial derived (microbial necromass) carbon in recalcitrant pool of SOC and their sequestration process in different types of ecosystems. Arguably, the contribution in SOC sequestration research on the fate of sequestered carbon in different types of soil and their stabilization mechanisms is insufficient. India is the country spread over regions from temperate to dry desert zones with different types of fragile ecosystems and its vulnerable nature to the global climate change. Therefore, the future research must focus on SOC sensitivity to temperature and SOC stabilization mechanisms in different ecosystems for better understanding of the soil carbon cycle.  相似文献   
53.
54.
55.

Background

Transplantation of hearts retrieved from donation after circulatory death (DCD) donors is an evolving clinical practice.

Objectives

The purpose of this study is to provide an update on the authors’ Australian clinical program and discuss lessons learned since performing the world’s first series of distantly procured DCD heart transplants.

Methods

The authors report their experience of 23 DCD heart transplants from 45 DCD donor referrals since 2014. Donor details were collected using electronic donor records (Donate Life, Australia) and all recipient details were collected from clinical notes and electronic databases at St. Vincent’s Hospital.

Results

Hearts were retrieved from 33 of 45 DCD donors. A total of 12 donors did not progress to circulatory arrest within the pre-specified timeframe. Eight hearts failed to meet viability criteria during normothermic machine perfusion, and 2 hearts were declined due to machine malfunction. A total of 23 hearts were transplanted between July 2014 and April 2018. All recipients had successful implantation, with mechanical circulatory support utilized in 9 cases. One case requiring extracorporeal membrane oxygenation subsequently died on the sixth post-operative day, representing a mortality of 4.4% over 4 years with a total follow-up period of 15,500 days for the entire cohort. All surviving recipients had normal cardiac function on echocardiogram and no evidence of acute rejection on discharge. All surviving patients remain in New York Heart Association functional class I with normal biventricular function.

Conclusions

DCD heart transplant outcomes are excellent. Despite a higher requirement for mechanical circulatory support for delayed graft function, primarily in recipients with ventricular assist device support, overall survival and rejection episodes are comparable to outcomes from contemporary brain-dead donors.  相似文献   
56.
57.
A young 33 year old male presented with non-resolving corneal infiltrate for 2 month duration in the right eye. KOH/ Calcoflour wet mount revealed sparsely septate fungal hyphae. Post therapeutic penetrating keratoplasty 3 doses of intracameral voriconazole(100μg/0.1ml) was administered suspecting recurrence. Fungal culture revealed non sporulating mould on SDA. PCR based DNA sequencing targeting the ITS region identified the fungal isolate as Mortierella wolfii (M. wolfii) belonging to zygomycetes. To the best of our knowledge, this is the first report of human fungal keratitis caused by M. wolfii.  相似文献   
58.
Objective The trade-off between the speed and simplicity of dictionary-based term recognition and the richer linguistic information provided by more advanced natural language processing (NLP) is an area of active discussion in clinical informatics. In this paper, we quantify this trade-off among text processing systems that make different trade-offs between speed and linguistic understanding. We tested both types of systems in three clinical research tasks: phase IV safety profiling of a drug, learning adverse drug–drug interactions, and learning used-to-treat relationships between drugs and indications.Materials We first benchmarked the accuracy of the NCBO Annotator and REVEAL in a manually annotated, publically available dataset from the 2008 i2b2 Obesity Challenge. We then applied the NCBO Annotator and REVEAL to 9 million clinical notes from the Stanford Translational Research Integrated Database Environment (STRIDE) and used the resulting data for three research tasks.Results There is no significant difference between using the NCBO Annotator and REVEAL in the results of the three research tasks when using large datasets. In one subtask, REVEAL achieved higher sensitivity with smaller datasets.Conclusions For a variety of tasks, employing simple term recognition methods instead of advanced NLP methods results in little or no impact on accuracy when using large datasets. Simpler dictionary-based methods have the advantage of scaling well to very large datasets. Promoting the use of simple, dictionary-based methods for population level analyses can advance adoption of NLP in practice.  相似文献   
59.
60.
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