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   788804篇
  免费   54545篇
  国内免费   1594篇
耳鼻咽喉   10863篇
儿科学   26178篇
妇产科学   19493篇
基础医学   121179篇
口腔科学   22890篇
临床医学   69196篇
内科学   154128篇
皮肤病学   19181篇
神经病学   56508篇
特种医学   27635篇
外国民族医学   77篇
外科学   115382篇
综合类   15364篇
现状与发展   2篇
一般理论   188篇
预防医学   59455篇
眼科学   18291篇
药学   59768篇
  3篇
中国医学   2823篇
肿瘤学   46339篇
  2021年   7666篇
  2019年   8256篇
  2018年   11396篇
  2017年   8244篇
  2016年   8804篇
  2015年   9617篇
  2014年   13284篇
  2013年   19778篇
  2012年   27003篇
  2011年   28578篇
  2010年   16544篇
  2009年   14900篇
  2008年   25169篇
  2007年   26845篇
  2006年   26861篇
  2005年   25465篇
  2004年   24568篇
  2003年   23162篇
  2002年   22291篇
  2001年   38582篇
  2000年   39586篇
  1999年   32101篇
  1998年   8041篇
  1997年   6718篇
  1996年   6896篇
  1995年   6942篇
  1994年   6354篇
  1992年   23487篇
  1991年   23373篇
  1990年   22722篇
  1989年   22408篇
  1988年   20352篇
  1987年   19695篇
  1986年   18718篇
  1985年   17548篇
  1984年   12859篇
  1983年   10893篇
  1982年   6036篇
  1979年   11644篇
  1978年   8241篇
  1977年   6877篇
  1976年   6657篇
  1975年   7325篇
  1974年   8594篇
  1973年   8215篇
  1972年   7717篇
  1971年   7209篇
  1970年   6936篇
  1969年   6385篇
  1968年   5854篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Bulletin of Experimental Biology and Medicine - We performed a comparative study of the effect of electroconvulsive therapy on anxiety in outbred rats and Sprague-Dawley rats with depressive-like...  相似文献   
92.
93.
Three-dimensional surgical planning is used widely in orthognathic surgery. Although numerous computer programs exist, the accuracy of soft tissue prediction remains uncertain. The purpose of this study was to compare the prediction accuracy of Dolphin, ProPlan CMF, and a probabilistic finite element method (PFEM). Seven patients (mean age 18 years; five female) who had undergone Le Fort I osteotomy with preoperative and 1-year postoperative cone beam computed tomography (CBCT) were included. The three programs were used for soft tissue prediction using planned and postoperative maxillary position, and these were compared to postoperative CBCT. Accurate predictions were obtained with each program, indicated by root mean square distances: RMSDolphin = 1.8 ± 0.8 mm, RMSProPlan = 1.2 ± 0.4 mm, and RMSPFEM = 1.3 ± 0.4 mm. Dolphin utilizes a landmark-based algorithm allowing for patient-specific bone-to-soft tissue ratios, which works well for cephalometric radiographs but has limited three-dimensional accuracy, whilst ProPlan and PFEM provide better three-dimensional predictions with continuous displacements. Patient or population-specific material properties can be defined in PFEM, while no soft tissue parameters are adjustable in ProPlan. Important clinical considerations are the topological differences between predictions due to the three algorithms, the non-negligible influence of the mismatch between planned and postoperative maxillary position, and the learning curve associated with sophisticated programs like PFEM.  相似文献   
94.

Background and objectives

A prompt and effective management of trauma patient is necessary. The aim of this case report is to highlight the importance of intraoperative echocardiography as a useful tool in patients suffering from refractory hemodynamic instability no otherwise explained.

Case report

A 41 year‐old woman suffered a car accident. At the emergency department, no abnormalities were found in ECG or chest X‐ray. Abdominal ultrasound revealed the presence of abdominal free liquid and the patient was submitted to urgent exploratory laparotomy. Nevertheless, she persisted suffering arterial hypotension and metabolic acidosis. Looking for the reason of her hemodynamic instability, intraoperative transthoracic echocardiography was performed, finding out the presence of pericardial effusion. Once the cardiac surgeon extracted pericardial clots, patient's situation improved clinically and analytically.

Conclusion

Every anesthesiologist should be able to use the intraoperative echocardiography as an effective tool in order to establish the appropriate measures to promote the survival of patients suffering severe trauma.  相似文献   
95.
ABSTRACT

Females are underrepresented in science, technology, engineering and mathematics (STEM) at all levels of society. Fewer females are completing STEM school subjects, graduating with STEM degrees, being employed as STEM professionals, and holding senior leadership and academic positions in STEM. However, unlike almost every other STEM discipline, the overall ratio of females is higher in many forensic science disciplines. For our sector, rather than having difficulty in attracting females, the bigger issue is how we retain and promote female talent. This complex issue is exacerbated by: gender pay gaps; family role expectations; lack of visible role models or mentors; discrimination and harassment; and bias during recruitment and promotion practices. We discuss barriers relevant for women in the forensic industry and offer potential solutions. These include flexible work arrangements, sponsorship programmes, and fostering and practising an inclusive workplace culture. Gender equity programmes and exemplar STEM organizations focused on a commitment to gender parity will be explored. Harnessing untapped female talent is as much a social justice issue as employing best practices for improving the quality, diversity and output of our forensic science workforce, and research and innovation strategies.  相似文献   
96.
Background: Egyptian street youth use substances including tobacco, illicit drugs, and pharmaceutical drugs. To understand the circumstances, including adverse childhood experiences, that place adolescents at risk for engaging in substance use, we conducted in-depth interviews among a sample of Egyptian street children. Methods: From youth residing at or attending Caritas, a non-profit organization, which provides shelter and education to street youth, seven girls and twelve boys, aged 12–18 years, participated in open-ended, in-depth interviews. Results: Eight out of the 19 participants reported family history (early exposure) to substance use; and seven of them were initiated by either a family member (sibling), friend or coworker. Most of the participants reported a history of conflict with or abuse (verbal or physical) by their parents or siblings, or stressful situations at home; they used substance(s) to alleviate their stress. Few attended school, and some were forced to work and help their family. Conclusions: Among Egyptian youth, adverse childhood experiences, such as poverty, child abuse, and family substance use, challenge somewhat susceptible youths and lead them to the path of substance use and addiction. Prevention intervention should be multifaceted, culturally adaptable, and primarily targeting the social environment during childhood.  相似文献   
97.
98.
The aim of this study was to determine the feasibility of applying MIPO of the humerus via the posterior approach and to observe the tension of the radial nerve in different elbow positions. Two separate incisions were made on the posterior aspect of the humerus in ten fresh cadavers (20 humeri). The radial nerve was identified at the proximal incision and the distances through which the nerve could be elevated from the bone with the elbow in flexion and extension were measured. A 10‐hole extra‐articular distal humeral locking compression plate was inserted and fixed through the submuscular tunnel. The tunnel was then explored to identify any entrapment of the radial nerve and to observe the anatomical relationship of the radial nerve to the plate and bone. There was no entrapment of the radial nerve or its branches. The distances through which the radial nerve could be elevated were greater with the elbow in extension than in flexion (P < 0.01). The radial nerve crossed the medial and lateral borders of the posterior surface of the humerus at 80.1–132 mm (average 104.7 mm) and 116.6–175.5 mm (average 142.7 mm) of its total length, respectively. The axillary nerve was located at 38.7–61.7 mm (average 47.9 mm) of total humeral length. MIPO of the humerus using the posterior approach is an alternative option for treating distal humeral shaft fracture. The risk of radial nerve injury can be minimized by careful dissection in the proximal incision. Clin. Anat. 32:176–182, 2019. © 2018 Wiley Periodicals, Inc.  相似文献   
99.

Background

Since recent reports have shown that (-)-Epigallocatechin-3-gallate (EGCG) could be used for treating proliferative and inflammatory disorders, we explored its use for the management of corneal chemical burns.

Materials and methods

Initially, EGCG was assayed on the rabbit corneal epithelial cell line RCE1(5T5) to establish the best testing conditions, and to avoid unwanted outcomes in the experimental animals. Then, we studied its effects on cell proliferation, cell cycle progression and cell differentiation. Afterwards, we instilled EGCG in experimental grade II corneal alkali burns in mice, three times a day up to 21 days, and evaluated by slit lamp examination and histological sections of corneal epithelial, corneal endothelial and stromal edema, as well as the presence of inflammatory cells and neovascularization.

Results

EGCG reduced cell growth and led to a decline in the proportion of proliferative cells in a concentration dependent manner. At 10 μM, EGCG promoted cell differentiation, an effect not related with apoptosis or cytotoxicity. When 10 μM EGCG was instilled in corneal alkali burns in mice three times a day up to 21 days, EGCG significantly reduced corneal opacity and neovascularization. The improved clinical appearance of the cornea was associated to a controlled epithelial growth; epithelial morphology was similar to that observed in normal epithelium and contrasted with the hyperproliferative, desquamating epithelium observed in control burn wounds. EGCG reduced corneal, stromal and endothelial edema, and wound inflammation.

Conclusion

This work constitutes the first evidence for the use of EGCG in the acute phase of a corneal alkali burn, representing a possible novel alternative to improve patient outcomes as an add-on therapy.  相似文献   
100.
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