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   70588篇
  免费   5980篇
  国内免费   2126篇
耳鼻咽喉   782篇
儿科学   932篇
妇产科学   1638篇
基础医学   10547篇
口腔科学   1809篇
临床医学   6364篇
内科学   13849篇
皮肤病学   1221篇
神经病学   4876篇
特种医学   2146篇
外国民族医学   9篇
外科学   9863篇
综合类   5411篇
现状与发展   4篇
一般理论   10篇
预防医学   3941篇
眼科学   2107篇
药学   6232篇
  6篇
中国医学   1312篇
肿瘤学   5635篇
  2023年   399篇
  2022年   450篇
  2021年   1079篇
  2020年   796篇
  2019年   1105篇
  2018年   1680篇
  2017年   1364篇
  2016年   1348篇
  2015年   1620篇
  2014年   2076篇
  2013年   2493篇
  2012年   3520篇
  2011年   3548篇
  2010年   2130篇
  2009年   1943篇
  2008年   2918篇
  2007年   3035篇
  2006年   2943篇
  2005年   2597篇
  2004年   2263篇
  2003年   2100篇
  2002年   2018篇
  2001年   5139篇
  2000年   5040篇
  1999年   4356篇
  1998年   1514篇
  1997年   1153篇
  1996年   712篇
  1995年   607篇
  1994年   556篇
  1993年   485篇
  1992年   2133篇
  1991年   1859篇
  1990年   1691篇
  1989年   1626篇
  1988年   1411篇
  1987年   1296篇
  1986年   1154篇
  1985年   958篇
  1984年   631篇
  1983年   496篇
  1982年   293篇
  1981年   219篇
  1980年   175篇
  1979年   316篇
  1978年   109篇
  1975年   80篇
  1974年   88篇
  1973年   109篇
  1972年   81篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Parotid lymph node (PLN) metastasis greatly worsens the prognosis of patients with oral squamous cell carcinoma (OSCC) and poses a great challenge for further treatment of OSCC. The clinicopathological characteristics and treatment strategies for PLN metastasis from OSCC need to be comprehensively elucidated. A retrospective review of OSCC patients who experienced postoperative PLN metastasis in our department between 2000 and 2018 was performed in this study. A total of 47 OSCC patients with postoperative PLN metastasis were identified. PLN with metastasis were divided into three groups based on the location: parotid tail (PLN-t), superficial lobe (PLN-sl), and deep lobe (PLN-dl). Most of the patients experienced PLN metastasis within less than 12 months after the primary surgery for OSCC. Comparatively, patients with PLN-sl metastasis were more prone to have infiltration of the facial nerve. The tongue and buccal mucosa were the most frequent primary sites associated with PLN metastasis from OSCC. PLNs in the parotid tail were most commonly affected by the metastasized OSCC. Consequently, we recommend a series of strategies for the prevention and treatment of PLN metastasis for OSCC patients. In conclusion, PLNs should not be overlooked during preoperative evaluation and postoperative follow-up examinations for OSCC patients.  相似文献   
4.
The objective of this study was to compare the implant longevity following two methods of peri-implant soft tissue optimization following free fibula flap (FFF): thinning of skin paddle (SP) and collagen matrix (CM). All patients who underwent rehabilitation with dental implants after mandibular reconstruction with FFF between June 2009 to May 2014 were retrospectively reviewed. Two methods of peri-implant soft tissue optimization were applied: (1) SP group, (2) CM group. Outcome measurements were: modified plaque index (mPI), modified sulcus bleeding index (mSBI), probing depth (PD), marginal bone loss (MBL), implant success rate and complication rates. A total of 24 patients with 69 implants were included in the study, with 8.7% (n = 6) of implants lost in 3 years. No statistically significant difference was found regarding the outcome measurements in both groups. Failed implants presented with statistically significant higher mPI, mSBI, PD and MBL scores during prosthesis delivery and subsequent follow-ups (P<0.03). In the SP group, one patient experienced SP necrosis which later underwent soft tissue optimization using CM. CM is an alternative peri-implant soft tissue, while thinning of SP is feasible if thickness is well controlled.  相似文献   
5.
6.
7.
8.
9.

Background

Prohibition of tobacco sales to minors is a provision of the World Health Organization Framework Convention on tobacco control. This measure is effective to reduce youth tobacco use, if the legislation adopted is properly implemented and enforced. Through the examples of France and Quebec, the objective of this study is to compare legislative frameworks prohibiting tobacco sales to minors, their enforcement, and possible impact on underage smoking.

Methods

Identification of legislative instruments, reports from public health authorities, and articles addressing the focused question was performed trough Medline and Google.

Results

Selling tobacco products to minors under 18 years of age has been banned by the law since 1998 in Quebec and 2009 in France. In 2011, in France for individuals aged 17, compliance with the law was 15%. In 2017 in France, 94% of 17-year-old daily smokers regularly bought their cigarettes in a tobacco store. Law enforcement controls and sanctions are non-existent. In 2013 in Quebec, 23% of underage smoking students usually bought their own cigarettes in a business. The compliance rate with the prohibition law rose from 37% in 2003 to 92.6% in 2017. An approach of underage “mystery shoppers” attempting to purchase tobacco products and dedicated inspectors has been implemented, and progressive sanctions are applied in case of non-compliance. In 2013, 12.2% of Quebec high school students and, in 2017, 34.1% of French 17 year olds reported using tobacco products in the last 30 days.

Conclusion

Only an improved law enforcement, through the training of tobacco retailer's, inspections and effective deterrent penalties for non-compliance, leads to an effective legislative measure in terms of public health.  相似文献   
10.
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