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   17722篇
  免费   1316篇
  国内免费   260篇
耳鼻咽喉   205篇
儿科学   377篇
妇产科学   572篇
基础医学   2253篇
口腔科学   806篇
临床医学   1650篇
内科学   3475篇
皮肤病学   284篇
神经病学   1897篇
特种医学   570篇
外科学   2178篇
综合类   912篇
一般理论   2篇
预防医学   1233篇
眼科学   462篇
药学   1222篇
  4篇
中国医学   183篇
肿瘤学   1013篇
  2023年   178篇
  2022年   310篇
  2021年   502篇
  2020年   321篇
  2019年   389篇
  2018年   416篇
  2017年   386篇
  2016年   390篇
  2015年   533篇
  2014年   563篇
  2013年   723篇
  2012年   948篇
  2011年   1106篇
  2010年   745篇
  2009年   665篇
  2008年   880篇
  2007年   921篇
  2006年   848篇
  2005年   788篇
  2004年   712篇
  2003年   725篇
  2002年   668篇
  2001年   502篇
  2000年   460篇
  1999年   411篇
  1998年   205篇
  1997年   178篇
  1996年   145篇
  1995年   128篇
  1994年   147篇
  1993年   121篇
  1992年   239篇
  1991年   236篇
  1990年   209篇
  1989年   202篇
  1988年   198篇
  1987年   161篇
  1986年   164篇
  1985年   161篇
  1984年   111篇
  1983年   114篇
  1982年   73篇
  1980年   63篇
  1979年   87篇
  1978年   81篇
  1977年   69篇
  1975年   96篇
  1974年   71篇
  1973年   64篇
  1972年   68篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
We studied amphotericin B (AMB) serum levels (n = 590) in 41 pediatric patients, who underwent allogeneic (21) or autologous (20) bone marrow transplantation (BMT). All patients received AMB orally as part of a total gut decontamination; 30/41 patients (73%) had AMB i.v. either for prophylaxis or therapy of fungal infections. Rapid initial dose escalation of AMB and the infusion over 1 h only were well tolerated by the children. Serum level monitoring allowed AMB long-term treatment safely to be administered in children suffering from transplantation-related complications (veno-occlusive disease of the liver, graft-versus-host disease of the liver). An h.p.l.c. method was used for monitoring AMB serum trough levels to avoid levels exceeding 2 mg/l. One lethal fungal infection was observed in 41 pediatric BMT recipients (2.4%). Rapidly increasing doses of AMB at start of therapy and drug monitoring by h.p.l.c. might help to reduce fungal mortality and renal toxicity by a dose sparing effect in BMT recipients.  相似文献   
93.
Behavioral disturbances have been reported with subthalamic (STN) deep brain stimulation (DBS) treatment in Parkinson's disease (PD). We report correlative functional imaging (fMRI) of mood and motor responses induced by successive right and left DBS. A 36-year-old woman with medically refractory PD and a history of clinically remitted depression underwent uncomplicated implantation of bilateral STN DBS. High-frequency stimulation of the left electrode improved motor symptoms. Unexpectedly, right DBS alone elicited several reproducible episodes of acute depressive dysphoria. Structural and functional magnetic resonance imaging (fMRI) imaging was carried out with sequential individual electrode stimulation. The electrode on the left was within the inferior STN, whereas the right electrode was marginally superior and lateral to the intended STN target within the Fields of Forel/zona incerta. fMRI image analysis (Analysis of Functional NeuroImages, AFNI) contrasting OFF versus ON stimulation identified significant lateralized blood oxygen level-dependent (BOLD) signal changes with DBS (P < 0.001). Left DBS primarily showed changes in motor regions: increases in premotor and motor cortex, ventrolateral thalamus, putamen, and cerebellum as well as decreases in sensorimotor/supplementary motor cortex. Right DBS showed similar but less extensive change in motor regions. More prominent were the unique increases in superior prefrontal cortex, anterior cingulate (Brodmann's area [BA] 24), anterior thalamus, caudate, and brainstem, and marked widespread decreases in medial prefrontal cortex (BA 9/10). The mood disturbance resolved spontaneously in 4 weeks despite identical stimulation parameters. Transient depressive mood induced by subcortical DBS stimulation was correlated with changes in mesolimbic cortical structures. This case provides new evidence supporting cortical segregation of motor and nonmotor cortico-basal ganglionic systems that may converge in close proximity at the level of the STN and the adjacent white matter tracts (Fields of Forel/zona incerta).  相似文献   
94.
Abstract The purpose of this study was to determine the clinical response to local delivery of tetracycline in relation to clinical and microbiological conditions of the other teeth. 4 deep pockets were monitored in 19 subjects with multiple deep periodontal lesions and high counts of P. gingivalis. In 9 patients (XT) only 2 of the selected lesions were treated by placement of tetracycline fibers (Actisite®). while the rest of the dentition was left untreated. In the other 10 patients, all teeth were supragingivally scaled and then treated by application of polymeric tetracycline HCl containing fibers, the whole dentition was subject to full mouth scaling and root planing, and the patients rinsed with 0.2% chlorhexidine (FT). A significant reduction in mean PPD was observed in all treated sites after two months. This reduction was maintained over the following 4 months. The magnitude of the effect was significantly greater in the FT group (1.74 mm) than in the LT group (0.88 mm). The mean attachment level changes were similar after 2 months in locally and fully treated subjects. A tendency of relapse was noted for treated sites in LT patients from month 2 to 6. A level of statistical significance was not reached for this effect. Data from measurements recorded at 6 sites around all teeth in the full mouth treated patients were analyzed using multiple linear regression. This analysis showed local changes in PPD and AL were significantly and strongly correlated with the baseline value of the respective parameter at the same site. In addition, more pocket depth reduction was noted if a site was not bleeding on probing at 6 months, if the location of a site was not approximal and if the tooth was not a second molar. Sites located on second molars showed also less AL gain than sites located on other teeth. Smokers showed significantly less reduction in PPD and significantly less AL gain. Furthermore, if subjects had a high % of pockets deeper than 4 mm at baseline they showed significantly less attachment gain.  相似文献   
95.
96.
Levodopa dose-related fluctuations in presumed olivopontocerebellar atrophy   总被引:1,自引:0,他引:1  
The parkinsonism that occurs in some patients with olivopontocerebellar atrophy (OPCA) can cause diagnostic confusion with idiopathic Parkinson's disease (IPD). The response to levodopa is usually a distinguishing feature, the OPCAs either failing to benefit or losing efficacy relatively quickly. A fluctuating response to levodopa in those OPCA patients who do benefit has not been emphasized in the literature previously. Reported here are three patients with presumed OPCA, dominated by parkinsonian features, who eventually developed typical fluctuations with morning akinesia, wearing off, and periodic lack of response related to meals. These fluctuations were a major source of disability and an important reason for diagnostic confusion with IPD. The possible mechanisms of these fluctuations are discussed.  相似文献   
97.
OBJECTIVE Little information is available regarding the regulation of serum acid-labile subunit (ALS) in human disease. We have studied alterations in serum ALS of the insulin-like growth factor (IGF) ternary complex in children with untreated insulin-dependent diabetes mellitus (IDDM) and subjects with severe burns before and after insulin therapy. In addition, we have investigated the effect of insulin plus GH on serum ALS in burn patients. DESIGN Serum samples were obtained from children with newly diagnosed and untreated IDDM before the initiation of insulin therapy and 1 month thereafter. Serum samples were also obtained from adult patients with severe burns who were on a continuous infusion of a carbohydrate-rich enteral diet via nasogastric and duodenal catheters under basal conditions, after a 1-week period of continuous insulin infusion, and after an additional week of insulin plus recombinant GH. PATIENTS Twenty children and adolescents with untreated IDDM, aged 1.2–16 years, and 6 young adult patients with severe burns aged 17–28 years were studied longitudinally. Control sera were obtained from age, sex and pubertal status matched subjects (for children with IDDM) and from fed healthy adults. MEASUREMENTS Serum insulin, GH, cortisol and IGF-I were measured by radioimmunoassay, and serum ALS levels were assessed by Western immunoblot before and after treatment periods. RESULTS Serum ALS levels were lower in untreated children with IDDM (69 ± 6% of control children). Insulin therapy significantly increased serum ALS (79 ± 5%, P<0.05) in these children. Patients with severe burns also had lower serum ALS levels (79 ± 10% of control adults). After one week of insulin therapy serum ALS levels increased to 90 ± 15% of control values (P<0.05). Addition of GH to insulin therapy for another week did not significantly further increase serum ALS levels (95 ± 27%). Serum IGF-I concentrations increased nearly 2.5-fold in diabetic subjects and fourfold in burn subjects at the end of the study periods. There were no proteolytic fragments of ALS in the sera studied. The deglycosylation pattern of ALS did not differ between diabetic and control sera. CONCLUSION Serum ALS levels were diminished in children with untreated IDDM and were partially restored after the initiation of insulin therapy. Serum ALS levels were also diminished in patients with severe burn injury and restored by insulin treatment. Addition of GH to insulin therapy did not significantly increase serum ALS levels over levels obtained during insulin therapy alone. These decreases in serum ALS were smaller than the decrease in serum IGF-I concentrations in both conditions, suggesting that IGF-I is the limiting factor for the ternary complex formation in the catabolic states. Insulin may regulate circulating ALS levels in catabolic states and helps to restore the IGF system.  相似文献   
98.
目的:研究术后切口感染危险因素,以降低切口感染率。方法:以1994~1996年外科手术病人为对象,进行病例对照研究。结果:病例组131例切口感染病人和对照组100例无切口感染病人在手术持续时间、术前抗生素使用种类、免疫抑制剂应用与否以及手术后抗生素使用天数等方面有显著性差异。且随着手术时间延长,术后切口感染的相对危险度呈明显递增趋势。结论:为降低术后切口感染率,必须尽量缩短手术时间,并减少术前术后抗生素使用天数和种类  相似文献   
99.
摘要:目的 探究赖氨酸特异性甲基转移酶2C(lysine specific methyltransferase 2C,KMT2C)在胃癌发生发展中的 作用及机制。方法 通过 TCGA 数据库分析 KMT2C在胃癌与癌旁的表达差异。采用 Western blot检测 KMT2C在胃 癌与癌旁临床样本中的表达差异。通过 Kaplan-Meier Plotter数据库分析 KMT2C 对胃癌患者预后的影响。采用细胞 实验(克隆形成、EdU 及 CCK-8检测)及皮下瘤负荷模型检测 KMT2C 在体内外对胃癌细胞增殖能力的影响。结果 KMT2C在胃癌中高表达。胃癌患者中 KMT2C高表达组相对于 KMT2C低表达组预后较差。敲减 KMT2C在体内外 均有抑制胃癌 细 胞 增 殖 的 作 用。基 因 集 富 集 分 析 (GSEA)发 现 KMT2C 影 响 c-Myc信 号 通 路。敲 减 KMT2C 后, H3K4me1蛋白表达水平降低,同时,CDK4的 mRNA 与蛋白表达水平降低。KMT2C与c-Myc核内结合促进了c-Myc 与 CDK4的启动子区域的结合。结论 KMT2C通过影响c-Myc/CDK4信号通路促进胃癌细胞增殖。  相似文献   
100.
Hairy cell leukemia (HCL) has been shown to be extraordinarily sensitive to treatment with alpha-interferon (IFN). In order to define clinically effective IFN doses associated with minimal toxicity, the therapeutic efficacy and side effects of recombinant IFN-alpha-2C treatment of HCL were compared for two different dose regimens: 18 patients (group A) received conventional doses of recombinant IFN-alpha-2C (2 x 10(6)U/m2) for a median time of 35 weeks (range 26-52 weeks), and 21 patients (group B) received optimum biological response-modifying doses of IFN-alpha-2C (0.2-0.6 x 10(6)U/m2) for a median time of 31 weeks (range 12-52 weeks). Interferon was administered daily subcutaneously for 3 months and then every second or third day. Induction of neopterin excretion was chosen as the marker for definition of biological response. The smallest IFN dose causing maximum in vivo induction of biosynthesis of the GTP-degradation product neopterin was deemed "biologically optimal." Both dose regimens were effective, but the low-dose regimen was almost free of toxicity. Thus, in HCL patients alpha-IFN related toxicity can be separated from its antineoplastic activity. Low doses of alpha-IFN should be considered for treatment of HCL patients who develop toxic side effects and for primary treatment of HCL patients with severe cytopenia.  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