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   15657篇
  免费   1362篇
  国内免费   513篇
耳鼻咽喉   84篇
儿科学   178篇
妇产科学   54篇
基础医学   2868篇
口腔科学   241篇
临床医学   816篇
内科学   1176篇
皮肤病学   106篇
神经病学   5801篇
特种医学   233篇
外国民族医学   1篇
外科学   668篇
综合类   1613篇
现状与发展   2篇
一般理论   1篇
预防医学   785篇
眼科学   120篇
药学   1706篇
  2篇
中国医学   592篇
肿瘤学   485篇
  2024年   23篇
  2023年   204篇
  2022年   184篇
  2021年   599篇
  2020年   466篇
  2019年   537篇
  2018年   501篇
  2017年   550篇
  2016年   550篇
  2015年   540篇
  2014年   886篇
  2013年   1267篇
  2012年   908篇
  2011年   1084篇
  2010年   880篇
  2009年   848篇
  2008年   928篇
  2007年   894篇
  2006年   829篇
  2005年   697篇
  2004年   617篇
  2003年   517篇
  2002年   432篇
  2001年   351篇
  2000年   262篇
  1999年   220篇
  1998年   209篇
  1997年   189篇
  1996年   171篇
  1995年   179篇
  1994年   118篇
  1993年   103篇
  1992年   105篇
  1991年   82篇
  1990年   68篇
  1989年   49篇
  1988年   54篇
  1987年   31篇
  1986年   32篇
  1985年   71篇
  1984年   54篇
  1983年   48篇
  1982年   45篇
  1981年   28篇
  1980年   24篇
  1979年   21篇
  1978年   13篇
  1977年   17篇
  1976年   15篇
  1973年   15篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
BACKGROUND: Effects of risperidone on cognitive function in children with disruptive behavior disorders (DBDs) and subaverage intelligence quotient (IQ) were assessed. METHODS: Data from two 6-week, double-blind, placebo-controlled studies (n = 228) were combined, as were three 1-year, open-label studies (n = 688). Patients with DBDs and subaverage IQ, 5 to14 years, received placebo or risperidone .02 to .06 mg/kg/day. Cognitive measures included the Continuous Performance Task (CPT) and Verbal Learning Test for Children (VLT-C). Efficacy was assessed using the Nisonger Child Behavior Rating Form (NCBRF). Adverse events were collected via spontaneous report; sedation was assessed using visual analog scale. RESULTS: Improvements on the NCBRF Conduct Problem subscale were significantly greater for risperidone- versus placebo-treated patients (-15.8 vs. -6.4, p < .0001) in short-term studies; significant reductions were observed in long-term studies (-16.3, p < .0001). No overall decline and some significant improvement in attention (CPT) and memory (VLT-C) were noted regardless of treatment in short-term studies. VLT-C improved significantly (p < .0001) for both groups, with no difference between treatment groups. Improvements in memory (VLT-C) and attention (CPT) were noted in long-term studies. Somnolence/sedation did not affect cognitive function. CONCLUSIONS: Cognitive function was not altered by risperidone in short-term studies and was maintained or improved with one year of treatment in children with DBDs and subaverage IQ, potentially representing age-appropriate gains.  相似文献   
32.
Profound T-cell depletion with the monoclonal antibody alemtuzumab facilitates reduced maintenance immunosuppression in abdominal and lung transplantation. While the phenotype of the post-depletional T cells has been characterized, little is known about their function. In the present study, global and CMV-specific T-cell function was assessed longitudinally in 23 lung transplant (LTx) recipients using T-cell assays (ImmuKnow and T Cell Memory, Cylex, Columbia, MD) during the first year posttransplant after induction therapy. Recovery of mitogen responses were seen at 2 weeks posttransplantation (65%PHA; 58% Con A), despite the low number of circulating T cells (<2%). These responses declined at 4-5 months (24%PHA; 54% Con A) and were partially reconstituted by 9 months (46% PHA; 73% Con A). CMV-specific responses recovered in 80% of R+ patients as early as 2 weeks posttransplant (n = 5) and 72% of patients had a memory response by 3 months (n = 11). In contrast, only 2 of 5 patients who did not exhibit memory responses pre-transplant (R-) developed transient CMV-specific T-cell responses. Our results show that profound depletion of T cells induced by alemtuzumab spares the functional subset of CMV-specific memory T cells. Conversely, CMV R- patients predepletion may require a prolonged period of prophylaxis.  相似文献   
33.
目的 探讨中药草苁蓉提取物对AD模型大鼠学习记忆能力及神经元凋亡的影响.方法 将60只健康SD大鼠随机分为正常组、假手术组、模型组和中药高、中、低剂量组.采用Aβ_(1-40)建立AD模型,中药组予以草苁蓉提取物按高、中、低3种不同剂量灌胃治疗,治疗结束后测定其学习记忆能力和神经元凋亡百分比.结果 中药组大鼠学习记忆能力高于模型组(P<0.01),而神经元凋亡百分比低于模型组(P<0.01).结论 中药草苁蓉提取物可有效改善AD大鼠学习记忆障碍,减少胆碱能神经元凋亡,从而起到治疗作用.  相似文献   
34.
髋臼粉碎性骨折合并压缩性缺损的治疗与对策   总被引:18,自引:4,他引:14  
目的探讨治疗髋臼粉碎性骨折合并压缩性缺损的手术方法.方法1997年7月~2005年2月,收治髋臼粉碎性骨折合并压缩性缺损43例,其中陈旧性骨折25例,新鲜骨折16例,畸形(大于90 d)2例;复杂骨折与缺损34例,简单骨折与缺损9例.缺损体积3~9 cm^3,平均4.5cm^3.采用改良髋臼入路,应用髋臼三维记忆内固定系统(ATMFS)三维记忆锁定碎骨;髋臼碎骨关节面整复法;自体髂骨髋臼后壁解剖性重建法;自体骨+人工骨填塞及骨腊隔离法等术后相关措施.结果所有患者随访5~86个月,平均15.7个月.粉碎骨折关节面粉碎+填补压缩体积至头臼解剖复位31例;自体髂骨后壁“解剖性重建头臼解剖复位”12例;40例患者经过平均5.3个月患侧髋关节功能达到健侧水平,1例股骨头缺血性坏死,2例异位骨化+股骨头缺血性坏死导致髋关节骨融合.结论本文介绍了治疗髋臼粉碎性骨折合并压缩性缺损的新方法与措施,有效地提高了股骨头与髋臼解剖对应率,为髋关节功能的恢复提供了新的思路.  相似文献   
35.
目的探讨乳头溢液的渗断和治疗方法,为合理的治疗提供科学依据。方法回顾分析手术治疗的207例乳头溢液病例资料。结果(1)在非哺乳期间发生乳头溢液多属病理性溢液;(2)通过美蓝法或平针头指示法行区段切除术,安全准确。结论(1)乳头溢液特别足血性溢液应手术治疗.对早期发现和早期治疗乳腺癌有鼋要的临床意义。(2)乳头溢液伴肿块者,不沧年龄大小、溢液性质均应手术治疗。  相似文献   
36.
BACKGROUND: First-degree relatives of individuals with schizophrenia show cognitive impairments that are similar to but less severe than their ill relatives. We have shown that memory impairments can be improved and prefrontal cortical (PFC) activity increased in individuals with schizophrenia by providing beneficial encoding strategies. The current study used a similar paradigm to determine whether siblings of individuals with schizophrenia (SIBs) also show increases in brain activity when presented with beneficial encoding strategies. METHODS: Twenty-one SIBs and 38 siblings of healthy comparison subjects underwent functional magnetic resonance imaging scans while engaged in deep (abstract/concrete judgments) and shallow (orthographic judgments) encoding. Subjects were then given a recognition memory test. RESULTS: The groups did not differ on encoding or recognition accuracy, and the SIBs benefited from deep encoding to a similar degree as control subjects. The SIBs showed deep encoding-related activity in a number of PFC regions typically activated during semantic processing. However, SIBs showed more activity than control subjects in three subregions of PFC (left BA 44 & BA 47 bilaterally). CONCLUSIONS: Siblings of individuals with schizophrenia benefit from supportive verbal encoding conditions. Like individuals with schizophrenia, SIBs also show increased task-related activity in a larger number of PFC subregions than control subjects during deep verbal encoding.  相似文献   
37.
Memory performance of elderly patients in the early stages of Alzheimer's disease (DAT) was compared with that of elderly control subjects. In explicit tests of recognition memory, which involve conscious recollection, the DAT patients were grossly impaired. In implicit tests of anagram solution and wordstem completion, which do not require conscious recollection, the DAT patients were not impaired. These findings further support the idea that a separate memory system, episodic memory, underlies conscious recollection, that it is this system which is most commonly damaged in amnesia, and that memory systems not involving conscious recollection may be spared in the early stages of Alzheimer's disease.  相似文献   
38.
目的研究神经节苷酯对老年性学习记忆减退鼠空间学习记忆的影响。方法用Moris水迷宫筛选老年性学习记忆减退昆明小鼠,腹腔注射神经节苷酯14天,然后测试小鼠定位航行和空间探索能力。结果与老年学习记忆减退鼠对照组比较,治疗组平均逃避潜伏期缩短,原平台游泳距离和穿环数次却增大,但均未达到老年学习记忆正常组和青年组水平。结论提示神经节苷酯可改善老年性学习记忆减退鼠空间学习记忆能力。  相似文献   
39.
促甲状腺素释放激素类似物YM14673对小鼠学习记忆的影响   总被引:1,自引:0,他引:1  
采用小鼠跳台法评价促甲状腺素释放激素类似物YM14673(ip1mg·kg-1)对正常成年小鼠被动回避学习记忆成绩的影响.结果表明YM14673对东莨菪碱,氯霉素和乙醇造成的小鼠记忆获得,巩固及再现障碍均有明显的改善作用.  相似文献   
40.
Osseointegrated dental implants have now become an accepted form of treatment for patients with a fully or partially missing dentition. The purpose of this study was to evaluate the performance of 3i threaded and cylindrical implants. During a 5-year period, a total of 1969 3i endosseous implants were placed at 6 centers in the United States and 2 elsewhere in the edentulous and partially edentulous jaws of 653 consecutive patients ranging in age from 18 to 82 years. Of the total number of implants placed, 1341 were commercially pure titanium threaded implants and 628 were titanium plasma-sprayed implants with a cylindrical configuration. A total of 28 patients with 110 implants were lost to follow-up. Implants in these patients were considered neither a success nor a failure. Success was predicated on the osseointegration of each and every implant followed in this analysis rather than the persistence of prosthetic function. Confirmed bone anchorage was considered essential for success. A total of 625 patients with 1871 implants remain in the study with a follow-up period ranging from 6 to 60 months. A total of 93 implants (5.0% of the total implants followed) were considered as failures. A mean implant survival rate was 95.0% for both the threaded and the cylindrical implant was calculated. The success rate of threaded implants was 97.0% in the mandible and 93.8% in the maxilla. The success rate for the 3.3mm cylindrical implants was 96.0% in the mandible and 95.5% in the maxilla, and the success rate of 4.0mm diameter cylindrical implants was 95% in the mandible and 92.0% in the maxilla. Causes of failure consisted of loss of osseointegration 2.3%crestal bone loss requiring periodontal therapy after the first year of function 1.7% and mechanical problems associated with the prosthesis 0.9%. This retrospective analysis of the 3i endosseous implant system is comparable to previous reports on other implant systems in terms of implant survival and prosthesis stability. It is demonstrated that 3i implants are predictable and can provide lasting osseointegration leading to improvement of oral function if the recommended surgical and restorative protocol is followed.  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