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   6831篇
  免费   327篇
  国内免费   28篇
耳鼻咽喉   153篇
儿科学   320篇
妇产科学   138篇
基础医学   613篇
口腔科学   226篇
临床医学   432篇
内科学   1408篇
皮肤病学   98篇
神经病学   389篇
特种医学   244篇
外科学   1521篇
综合类   89篇
现状与发展   1篇
一般理论   5篇
预防医学   219篇
眼科学   136篇
药学   543篇
中国医学   28篇
肿瘤学   623篇
  2024年   2篇
  2023年   28篇
  2022年   71篇
  2021年   197篇
  2020年   81篇
  2019年   133篇
  2018年   180篇
  2017年   136篇
  2016年   169篇
  2015年   217篇
  2014年   318篇
  2013年   356篇
  2012年   562篇
  2011年   613篇
  2010年   364篇
  2009年   316篇
  2008年   446篇
  2007年   478篇
  2006年   448篇
  2005年   447篇
  2004年   395篇
  2003年   356篇
  2002年   333篇
  2001年   68篇
  2000年   45篇
  1999年   39篇
  1998年   47篇
  1997年   44篇
  1996年   31篇
  1995年   26篇
  1994年   34篇
  1993年   30篇
  1992年   17篇
  1991年   32篇
  1990年   20篇
  1989年   17篇
  1988年   9篇
  1987年   5篇
  1986年   6篇
  1985年   6篇
  1984年   7篇
  1983年   7篇
  1982年   9篇
  1981年   12篇
  1980年   5篇
  1979年   7篇
  1977年   4篇
  1976年   3篇
  1974年   2篇
  1970年   2篇
排序方式: 共有7186条查询结果,搜索用时 31 毫秒
71.
72.
73.
Traumatic brain injury (TBI) and sub-arachnoid hemorrhage (SAH) are major causes of long-term disability, mortality, and enormous economic costs to society. The full spectrum of neurological damage created by TBI or SAH is not usually manifested at the time of injury, but evolves gradually over the course of hours to days (or weeks) following these injuries. Angiopoietins, important regulators of vascular structure and function, are hallmark indicators of vascular injury and may therefore represent promising targets in the treatment of SAH and TBI. In animal models and human tissues, normal intracerebral and pial vessels show strong expression of Angiopoietin-1 (Ang-1), but only minimal expression or presentation of Angiopoietin-2 (Ang-2). After several types of neurotrauma, the ratios of Ang-1 and Ang-2 expression in brain microvessel are disturbed and appear to contribute to the remarkable loss of blood–brain barrier (BBB) in these injuries. Angiopoietins levels, and perhaps more importantly, Angiopoietin ratios (1:2) may have novel and important diagnostic and prognostic uses in TBI and SAH brain injury. Ang-1/2 evaluation in plasma, serum and cerebrospinal fluid may provide new therapeutic modalities which can modify ‘secondary’ forms of brain injury after TBI and SAH.  相似文献   
74.
75.
Poor mental health functioning among persons living with HIV (PLHIV) has gained considerable attention particularly in low-income countries that disproportionately carry the global HIV/AIDS burden. Fewer studies, however, have examined the relationship between poverty indicators and mental health among PHLIV in India. Based on this cross-sectional study of 196 HIV-seropositive adults who received medical services at Shalom AIDS Project in Delhi, India, structural equation modeling and mediation analysis were employed to estimate the associations between poverty indices (household asset index, food security, unemployment, water treatment, sanitation), HIV-health factors (illness in the past 3 months, co-morbid medical conditions), and psychological distress. In the final model, ownership of fewer household assets was associated with higher levels of food insecurity, which in turn was associated with higher psychological distress. Also, the household asset index, food insecurity, and unemployment had a larger effect on psychological distress than new opportunistic infections. These findings build on increasing evidence that support concerted efforts to design, evaluate, and refine HIV mental health interventions that are mainstreamed with livelihood programming in high poverty regions in India.  相似文献   
76.
Self-controlled hyperthermia is a non-invasive technique used to kill or destroy cancer cells while preserving normal surrounding tissues. We have explored bulk magnetic Ni-Si and Ni-Al alloys as a potential thermoseeds. The structural, magnetic and magnetocaloric properties of the samples were investigated, including saturation magnetisation, Curie temperature (TC), and magnetic and thermal hysteresis, using room temperature X-ray diffraction and magnetometry. The annealing time, temperature and the effects of homogenising the thermoseeds were studied to determine the functional hyperthermia applications. The bulk Ni-Si and Ni-Al binary alloys have Curie temperatures in the desired range, 316?K–319?K (43?°C–46?°C), which is suitable for magnetic hyperthermia applications. We have found that TC strictly follows a linear trend with doping concentration over a wide range of temperature. The magnetic ordering temperature and the magnetic properties can be controlled through substitution in these binary alloys.  相似文献   
77.
The hemagglutinin (HA) gene of novel Swine Origin Influenza A/California/04/2009 (H1N1) was engineered for expression in Pichia pastoris as a soluble secreted protein. The full length HA-synthetic gene having ?? secretory tag under the control of AOX1 promoter was integrated into P. pastoris genome through homologous recombination. The resultant Pichia clones having single and multiple copy integrants of the expression cassettes were screened for the expression of full length HA protein in the culture supernatant. In order to completely exploit the expression potential of the P. pastoris expression system, a systematic investigation on the influence of gene copy number on the expression of the recombinant protein was made. A panel of Pichia clones carrying increasing copies of the heterologous gene was selected based on Geneticin resistance and SYBR green-based quantitative real-time PCR approach. Using these strategies, recombinant Pichia transformants carrying up to a maximum of four to six copies of the transgene were identified. After optimising the expression conditions for shaker flask culture, the resultant clones demonstrated that the increase in copy number results in a proportional elevation in the expression level of H1N1HA recombinant protein. Our findings clearly suggest that the gene dosage effect play a vital role in high level expression of the pandemic Influenza HA protein in yeast system.  相似文献   
78.
Since the advent of cochlear implant (CI) surgery in the 1960s, there have been remarkable technological and surgical advances enabling excellent speech perception in quiet with many CI users able to use the telephone. However, many CI users struggle with music perception, particularly with the pitch-based and melodic elements of music. Yet remarkably, despite poor music perception, many CI users enjoy listening to music based on self-report questionnaires, and prospective studies have suggested a disassociation between music perception and enjoyment. Music enjoyment is arguably a more functional measure of one’s listening experience, and thus enhancing one’s listening experience is a worthy goal. Recent studies have shown that re-engineering music to reduce its complexity may enhance enjoyment in CI users and also delineate differences in musical preferences from normal hearing listeners.  相似文献   
79.
Restoration of swallowing in a patient with dysphagia due to nondilatable corrosive stricture of esophagus remains a surgical challenge. Organs available for replacement are stomach, jejunum, or colon. Jejunum is useful to replace a small segment, whereas stomach and colon are required for a long-segment replacement. In cases where the stomach is also injured, colon remains the only option. The route of colonic interposition has also been a subject of debate over the years. Antesternal, retrosternal, or esophageal bed passage are the routes described. In the present series, the data of antesternal colonic interposition (ACI) performed for nondilatable benign esophageal strictures in 32 patients (1988–2011) have been retrospectively analyzed. The results indicate that ACI for corrosive strictures is a quick and simple procedure. Thoracotomy is avoided and anastomosis is easily performed in the neck, and mortality rate due to anastomotic failure or graft failure is diminished. This retrospective analysis discusses the ease, effectiveness, quality of life, morbidity, and mortality of ACI and compares the pros and cons of ACI with other procedures described in the literature.  相似文献   
80.
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