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   952397篇
  免费   69455篇
  国内免费   3317篇
耳鼻咽喉   13256篇
儿科学   24630篇
妇产科学   23531篇
基础医学   135075篇
口腔科学   28723篇
临床医学   83048篇
内科学   185122篇
皮肤病学   19554篇
神经病学   73124篇
特种医学   37803篇
外国民族医学   95篇
外科学   154120篇
综合类   22887篇
一般理论   240篇
预防医学   63092篇
眼科学   22070篇
药学   75371篇
  19篇
中国医学   3864篇
肿瘤学   59545篇
  2018年   9653篇
  2017年   7994篇
  2016年   8490篇
  2015年   10005篇
  2014年   13653篇
  2013年   19003篇
  2012年   26301篇
  2011年   27385篇
  2010年   16276篇
  2009年   15425篇
  2008年   26166篇
  2007年   27189篇
  2006年   27871篇
  2005年   26819篇
  2004年   25514篇
  2003年   24485篇
  2002年   23889篇
  2001年   55295篇
  2000年   56999篇
  1999年   47327篇
  1998年   10640篇
  1997年   9319篇
  1996年   9373篇
  1995年   9154篇
  1994年   8482篇
  1993年   7739篇
  1992年   35636篇
  1991年   34072篇
  1990年   32835篇
  1989年   31965篇
  1988年   29089篇
  1987年   28327篇
  1986年   26339篇
  1985年   25192篇
  1984年   17839篇
  1983年   15145篇
  1982年   7767篇
  1981年   6750篇
  1979年   15765篇
  1978年   10583篇
  1977年   9024篇
  1976年   7847篇
  1975年   8609篇
  1974年   10443篇
  1973年   9843篇
  1972年   9345篇
  1971年   8845篇
  1970年   8410篇
  1969年   7905篇
  1968年   7196篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
ObjectiveTo determine prognostic factors and survival patterns for different treatment modalities for nasal cavity (NC) and paranasal sinus (PS) mucosal melanoma (MM).MethodsPatients from 1973 to 2013 were analyzed using the Surveillance, Epidemiology, and End Results (SEER) database. Kaplan-Meier method and multivariable cox proportional hazard modeling were used for survival analyses.ResultsOf 928 cases of mucosal melanoma (NC = 632, PS = 302), increasing age (Hazard Ratio [HR]:1.05/year, p < 0.001), T4 tumors (HR: 1.81, p = 0.02), N1 status (HR: 6.61, p < 0.001), and PS disease (HR: 1.50, p < 0.001) were associated with worse survival. Median survival length was lower for PS versus NC (16 versus 26 months, p < 0.001). Surgery and surgery + radiation therapy (RT) improved survival over non-treatment or RT alone (p < 0.001). Adding RT to surgery did not yield a survival difference compared with surgery alone (p = 0.43). Five-year survival rates for surgery and surgery + RT were similar, at 27.7% and 25.1% (p = 0.43).ConclusionSurgery increased survival significantly over RT alone. RT following surgical resection did not improve survival.  相似文献   
2.
Tympanic membranes (TM) that have healed spontaneously after perforation present abnormalities in their structural and mechanical properties; i.e., they are thickened and abnormally dense. These changes result in a deterioration of middle ear (ME) sound transmission, which is clinically presented as a conductive hearing loss (CHL). To fully understand the ME sound transmission under TM pathological conditions, we created a gerbil model with a controlled 50% pars tensa perforation, which was left to heal spontaneously for up to 4 weeks (TM perforations had fully sealed after 2 weeks). After the recovery period, the ME sound transmission, both in the forward and reverse directions, was directly measured with two-tone stimulation. Measurements were performed at the input, the ossicular chain, and output of the ME system, i.e., at the TM, umbo, and scala vestibuli (SV) next to the stapes. We found that variations in ME transmission in forward and reverse directions were not symmetric. In the forward direction, the ME pressure gain decreased in a frequency-dependent manner, with smaller loss (within 10 dB) at low frequencies and more dramatic loss at high frequency regions. The loss pattern was mainly from the less efficient acoustical to mechanical coupling between the TM and umbo, with little changes along the ossicular chain. In the reverse direction, the variations in these ears are relatively smaller. Our results provide detailed functional observations that explain CHL seen in clinical patients with abnormal TM, e.g., caused by otitis media, that have healed spontaneously after perforation or post-tympanoplasty, especially at high frequencies. In addition, our data demonstrate that changes in distortion product otoacoustic emissions (DPOAEs) result from altered ME transmission in both the forward and reverse direction by a reduction of the effective stimulus levels and less efficient transfer of DPs from the ME into the ear canal. This confirms that DPOAEs can be used to assess both the health of the cochlea and the middle ear.  相似文献   
3.
4.
目的:了解中国居民对执业药师立法的支持度及其影响因素。方法:通过问卷对抽取的120个城市的居民进行横断面研究,采用多重线性回归分析居民对执业药师立法意愿得分的相关因素。结果:中国居民对于执业药师立法支持度平均得分为69.04分。本科及以上学历(β=0.04)、轻度焦虑(β=0.03)、重度压力(β=0.05)居民对执业药师立法支持度较高,P均<0.01;中重度抑郁(β=-0.02,P<0.01)居民对执业药师立法支持度较低。家庭健康状况(β=0.30)、自我健康感觉(β=0.25)、自我管理能力(β=0.13)、健康素养(β=0.12)和领悟社会支持(β=0.09)均对居民执业药师立法支持度得分产生显著的正向影响(P<0.01)。结论:文化程度、焦虑、压力、抑郁、家庭健康状况、自我健康感觉、自我管理能力、健康素养和社会支持均是影响居民对执业药师立法态度的主要因素。  相似文献   
5.
目的调查少数民族地区青少年对新冠疫情的认知及应对情况。方法采用分层抽样的方法,通过“问卷星”在线平台对香格里拉市1949名在校学生进行调查。结果结果显示,81.94%的学生在2020年1月初之前已知晓疫情;83.12%的学生通过电视和微信知晓疫情;9333%的学生认为病毒通过飞沫传播;94.80%的学生会通过戴口罩、不聚餐等方式进行防护;疫情相关知识的正确率为71.44%。不同年龄、性别、民族、专业、生源地、家庭年收入的学生对部分调查问题的差异有统计学意义(P<0.05)。结论学生对疫情认知整体情况较好,部分问题仍有较大提升空间。学校应做好疫情常态化防控,完善心理疏导体系,多措并举,引导学生做好自我防护。  相似文献   
6.
7.
目的:探讨新生儿耐碳青霉烯类肺炎克雷伯菌的抗感染治疗的药学实践。方法:回顾性分析1例临床药师参与的新生儿耐碳青霉烯类肺炎克雷伯菌的抗感染治疗的案例。结果:临床药师结合药敏试验报告和患儿病情,参与抗感染治疗方案的制定并进行药学监护,最终使患儿感染得到控制并顺利出院。结论:在耐碳青霉烯类肺炎克雷伯菌的治疗中,临床药师应发挥专业优势,参与临床治疗,提高药物治疗的安全性和有效性  相似文献   
8.
Galactosyl transferase knock-out pig lungs fail rapidly in baboons. Based on previously identified lung xenograft injury mechanisms, additional expression of human complement and coagulation pathway regulatory proteins, anti-inflammatory enzymes and self-recognition receptors, and knock-down of the β4Gal xenoantigen were tested in various combinations. Transient life-supporting GalTKO.hCD46 lung function was consistently observed in association with either hEPCR (n = 15), hTBM (n = 4), or hEPCR.hTFPI (n = 11), but the loss of vascular barrier function in the xenograft and systemic inflammation in the recipient typically occurred within 24 h. Co-expression of hEPCR and hTBM (n = 11) and additionally blocking multiple pro-inflammatory innate and adaptive immune mechanisms was more consistently associated with survival >1 day, with one recipient surviving for 31 days. Combining targeted genetic modifications to the lung xenograft with selective innate and adaptive immune suppression enables prolonged initial life-supporting lung function and extends lung xenograft recipient survival, and illustrates residual barriers and candidate treatment strategies that may enable the clinical application of other organ xenografts.  相似文献   
9.
Quality of Life Research - During the COVID-19 pandemic, widespread public health measures were implemented to control community transmission. The association between these measures and...  相似文献   
10.
Forensic Toxicology - Various forms of cannabidiol (CBD)-containing products are sold in Japan. CBD is easily converted to mixtures of ?9-tetrahydrocannabinol (?9-THC) and its isomer,...  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