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   1570篇
  免费   156篇
  国内免费   12篇
耳鼻咽喉   7篇
儿科学   48篇
妇产科学   18篇
基础医学   135篇
口腔科学   21篇
临床医学   409篇
内科学   135篇
皮肤病学   18篇
神经病学   92篇
特种医学   59篇
外科学   441篇
综合类   17篇
预防医学   82篇
眼科学   43篇
药学   38篇
中国医学   1篇
肿瘤学   174篇
  2021年   11篇
  2019年   17篇
  2018年   35篇
  2017年   16篇
  2016年   14篇
  2015年   27篇
  2014年   41篇
  2013年   34篇
  2012年   60篇
  2011年   61篇
  2010年   39篇
  2009年   51篇
  2008年   74篇
  2007年   78篇
  2006年   56篇
  2005年   86篇
  2004年   72篇
  2003年   70篇
  2002年   63篇
  2001年   64篇
  2000年   50篇
  1999年   60篇
  1998年   34篇
  1997年   28篇
  1996年   33篇
  1995年   22篇
  1994年   18篇
  1993年   17篇
  1992年   47篇
  1991年   47篇
  1990年   38篇
  1989年   39篇
  1988年   48篇
  1987年   36篇
  1986年   37篇
  1985年   31篇
  1984年   16篇
  1983年   8篇
  1981年   10篇
  1980年   7篇
  1978年   9篇
  1976年   13篇
  1975年   11篇
  1974年   12篇
  1973年   15篇
  1972年   6篇
  1971年   8篇
  1970年   8篇
  1969年   8篇
  1968年   7篇
排序方式: 共有1738条查询结果,搜索用时 15 毫秒
51.
Posterior cortical atrophy (PCA) is a rare neurodegenerative syndrome characterized by initial predominant visuoperceptual deficits followed by a progressive decline in other cognitive functions. This syndrome has not been as thoroughly described as other dementias, particularly from a neuropsychological evolution perspective with only a few studies describing the evolution of its cognitive progression. In this investigation we review the literature on this rare condition and we perform a 7-year neuropsychological and neuroradiological follow-up of a 64-year-old man with PCA. The subject’s deficits initially appeared in his visuoperceptual skills with later affectation appearing in language and other cognitive functions, this being coherent with the patient’s parieto-temporal atrophy evolution.  相似文献   
52.
The incidence of diarrhea associated with infection by Vibrio species was investigated among attendees at the 1986 Interscience Conference on Antimicrobial Agents and Chemotherapy held in New Orleans. Twelve percent of respondents reported diarrhea; the risk of diarrhea was significantly higher in those who ate raw or cooked oysters (relative risk = 1.5, P = .005). At least one Vibrio species was recovered from 51 (11%) of 479 persons submitting stool specimens; however, only 15 (29%) of those with a positive stool culture also reported diarrhea. Of the five Vibrio species identified, V. parahaemolyticus was most common and was most strongly associated with diarrhea. V. cholerae serogroup O1 was not isolated despite the occurrence of a cholera outbreak during the same time period in Louisiana. Cultures of raw and cooked seafood served in local restaurants yielded five different Vibrio species. Although asymptomatic passage of Vibrio organisms was common among persons eating seafood, the risk of Vibrio gastroenteritis was low.  相似文献   
53.
This paper is focused on selected items from an exploratory study of nurse tutor-student nurse role-relationships. Aspects of the teacher-student and counsellor-client dimensions of the relationship are reported. The research was conducted from a sociological perspective using role theory as the organizing theoretical framework. An 'ideal type' tutor-student relationship was proposed from the findings. There was concensus between tutors and students that tutors acted in a caring way towards students but many constraints were identified which inhibited students with problems from seeking help from tutors and prevented tutors from offering all the help which they wished to give to students.  相似文献   
54.
目的:严重的多节段脊髓型颈椎病单纯前路或后路手术都有其局限性。观察一期前后路联合手术并自体髂骨植骨及带锁钢板内固定材料置入在治疗多节段脊髓型颈椎病中的应用价值。方法:选择2004-11/2006-12本院12例多节段脊髓型颈椎病患者,均采用一期前后路减压、自体髂骨植骨融合、带锁钢板内固定联合手术。其中男9例,女性3例,年龄49~75岁;3节段受累9例,4节段受累3例(突出节段分布:C3~66例,C4~73例,C3~73例)。全部病例进行临床随访,患者均对本试验知情同意。采用mJOA评分标准对患者神经功能改善情况进行评定;术前颈椎侧位片测量,以D值(C4椎体后下缘到齿突后缘与C7椎体后下缘连线的垂直距离)评价颈椎(C2~7)弧度;根据颈椎伸屈动态侧位片C2和C7椎体后缘切线相交所成的夹角之和评价颈椎(C2~7)活动范围。主要以电话随访和问卷填写的方式,分别从神经功能改善情况、颈椎弧度、活动范围及术后并发症等进行随访观察。结果:①12例患者全部得到随访,术后随访时间6~28个月,平均(16±6)个月。②所有植骨均获得骨性愈合;疗效结果中优4例(33.3%);良6例(50%);无效2例(16.7%);颈椎D值术前(3.9±1.4)mm,术后即刻(8.5±1.7)mm,随访时(8.1±2.5)mm。术前与术后差异有显著性(P<0.01),术后与随访时差异无显著性(P=0.251);颈椎活动范围术前(36.3±4.0)°,随访时(10.6±2.7)°,与术前相比差异具有显著性(P<0.01)。③术后C5神经根麻痹1例,为感觉及运动混合型,8个月随访时,感觉功能恢复,肩关节外展肌力从术后Ⅱ级恢复至Ⅳ级;1例术后6个月出现"S"畸形而再次压迫脊髓,神经功能改善停滞,目前处于随访中。结论:一期前后路手术并自体髂骨植骨及带锁钢板内固定材料置入减压充分、彻底,而且前路手术能重建颈椎稳定性,恢复颈椎生理前凸和椎间高度,并且后路减压术又能预防相邻颈椎退变引起的脊髓继发的压迫。  相似文献   
55.
Patients that have suffered a major injury may sustain a period of immunocompromise and altered Th1/Th2 cytokine balance that can predispose them to opportunistic infections. Pseudomonas aeruginosa is frequently a causative organism for nosocomial infections in critically ill patients and is associated with high mortality. We previously mimicked this clinical scenario by challenging mice with P. aeruginosa 5 days after a cecal ligation and puncture (CLP) procedure. Mice that were subjected to CLP had reduced ability to clear bacteria, significantly lower gamma interferon (IFN-gamma) concentrations in plasma, and significantly elevated levels of interleukin 10 (IL-10) in plasma in response to the Pseudomonas challenge compared to uninjured control mice. We investigated the significance of the alteration in IFN-gamma by administering recombinant IFN-gamma to post-CLP mice at the time of Pseudomonas challenge and by challenging IFN-gamma knockout (IFN-gamma KO) mice with Pseudomonas. Administration of IFN-gamma to post-CLP mice attenuated IL-10 secretion and enhanced IL-12 secretion but did not improve bacterial clearance or survival after Pseudomonas challenge. Furthermore, IFN-gamma KO mice had significantly higher plasma IL-10 concentrations but did not exhibit impaired bacterial clearance or increased mortality following Pseudomonas challenge. These data indicate that systemic administration of IFN-gamma effectively reverses alterations in immune function that are commonly associated with immunosuppression in critically injured mice but does not improve bacterial clearance or survival following Pseudomonas challenge. Further, endogenous IFN-gamma does not appear to contribute significantly to early clearance of Pseudomonas bacteremia, nor does it affect the mortality rate after a lethal Pseudomonas challenge.  相似文献   
56.

Background  

Painless, rapid, controlled, minimally invasive molecular transport across human skin for drug delivery and analyte acquisition is of widespread interest. Creation of microconduits through the stratum corneum and epidermis is achieved by stochastic scissioning events localized to typically 250 μm diameter areas of human skin in vivo.  相似文献   
57.
Chen JM, Férec C, Cooper DN. Revealing the human mutome. The number of known mutations in human nuclear genes, underlying or associated with human inherited disease, has now exceeded 100,000 in more than 3700 different genes (Human Gene Mutation Database). However, for a variety of reasons, this figure is likely to represent only a small proportion of the clinically relevant genetic variants that remain to be identified in the human genome (the ‘mutome’). With the advent of next‐generation sequencing, we are currently witnessing a revolution in medical genetics. In particular, whole‐genome sequencing (WGS) has the potential to identify all disease‐causing or disease‐associated DNA variants in a given individual. Here, we use examples of recent advances in our understanding of mutational/pathogenic mechanisms to guide our thinking about possible locations outwith gene‐coding sequences for those disease‐causing or disease‐associated variants that are likely so often to have been overlooked because of the inadequacy of current mutation screening protocols. Such considerations are important not only for improving mutation‐screening strategies but also for enhancing the interpretation of findings derived from genome‐wide association studies, whole‐exome sequencing and WGS. An improved understanding of the human mutome will not only lead to the development of improved diagnostic testing procedures but should also improve our understanding of human genome biology.  相似文献   
58.
Journal of Assisted Reproduction and Genetics - To study how SART-member fertility clinics communicated via clinic websites during the first wave of the COVID-19 pandemic following publication of...  相似文献   
59.
OBJECTIVES: To evaluate the effectiveness of excisional revision of filtering blebs for hypotony or leakage when more conservative measures have failed. PATIENTS AND METHODS: Retrospective review of all patients who underwent excisional revision of a filtering bleb for hypotony (intraocular pressure [IOP] < 5 mm Hg) or leakage during a 3 year period. The revision consisted of excision of the avascular bleb, mobilization of the surrounding conjunctiva, and suturing of the conjunctiva at the limbus. RESULTS: Sixteen patients were included in the study. The average age was 66.3 +/- 14.8 years (range, 39-83). Revision followed trabeculectomy in 11 cases, combined phacoemulsification-trabeculectomy in three cases, and inadvertent blebs in two cases. Five cases had bleb leaks without hypotony, four cases had hypotony alone, and seven cases had both hypotony and a bleb leak. Average follow-up after bleb revision was 25 +/- 11 months (range, 9-43). Average IOP increased from 3.8 +/- 5.6 mm Hg (range, 0-22) to 11.9 +/- 4.1 mm Hg (range, 3-18), with an average of 1.1 +/- 1.1 medication (range, 0-3). The IOP at the last visit was < 15 mm Hg in all but two patients, with 10 of the 16 patients requiring medications. At the last follow-up examination, visual acuity had improved > or = two lines in nine patients and was reduced two lines in one patient. Five patients had early postoperative limbal wound leaks; resuturing was required in one case. CONCLUSIONS: Excisional bleb revision is an effective technique to correct hypotony or leakage after filtering surgery when other methods have failed. Intraocular pressure control is often maintained with the use of medications.  相似文献   
60.
The structures of ketanserin (1) and spiperone (2) were examined in detail to determine the role of various substituent groups on 5-HT(2A) receptor affinity and selectivity. It was found that the presence of the quinazoline ring of ketanserin detracts from selectivity and that various ring-opened analogs displayed ketanserin-like affinity and up to 30-fold enhanced selectivity. The triazaspirodecanone portion of spiperone is a major determinant of its 5-HT affinity and selectivity. The conformational rigidity imposed by the ring, as well as the nature of the N(1)-substituent, are important factors in controlling binding at 5-HT(2A), 5-HT(2C), 5-HT(1A), and dopamine D2 receptors. Replacement of the N(1)-phenyl ring of spiperone with a methyl group (KML-010; 48) resulted in a compound that binds at 5-HT(2A) receptors with slightly lower affinity than spiperone, but that lacked affinity (Ki >10,000 nM) for 5-HT(2C) and 5-HT(1A) receptors and binds with 400-fold reduced affinity at D2 receptors.  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