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   45679篇
  免费   2070篇
  国内免费   379篇
耳鼻咽喉   455篇
儿科学   1017篇
妇产科学   531篇
基础医学   6072篇
口腔科学   758篇
临床医学   2791篇
内科学   11736篇
皮肤病学   1067篇
神经病学   3495篇
特种医学   1836篇
外科学   7798篇
综合类   180篇
一般理论   6篇
预防医学   1237篇
眼科学   1030篇
药学   2859篇
中国医学   180篇
肿瘤学   5080篇
  2023年   256篇
  2022年   533篇
  2021年   961篇
  2020年   504篇
  2019年   699篇
  2018年   969篇
  2017年   749篇
  2016年   929篇
  2015年   1036篇
  2014年   1316篇
  2013年   1685篇
  2012年   2708篇
  2011年   3012篇
  2010年   1693篇
  2009年   1571篇
  2008年   2815篇
  2007年   3024篇
  2006年   3027篇
  2005年   3036篇
  2004年   3137篇
  2003年   3173篇
  2002年   3152篇
  2001年   490篇
  2000年   397篇
  1999年   554篇
  1998年   775篇
  1997年   648篇
  1996年   617篇
  1995年   512篇
  1994年   457篇
  1993年   491篇
  1992年   305篇
  1991年   295篇
  1990年   242篇
  1989年   227篇
  1988年   230篇
  1987年   178篇
  1986年   139篇
  1985年   147篇
  1984年   159篇
  1983年   123篇
  1982年   126篇
  1981年   158篇
  1980年   130篇
  1979年   81篇
  1978年   104篇
  1977年   80篇
  1976年   64篇
  1975年   52篇
  1974年   40篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Recent behavioural studies have provided evidence that the amygdala modulates hippocampal-dependent memory. To test the possibility that the amygdala modulates hippocampal synaptic plasticity, we investigated the effects of surgical lesions of the amygdaloid nuclei on the induction of long-term potentiation (LTP) in the dentate gyrus of anaesthetized rats. Previously we reported that LTP in the dentate gyrus was attenuated by lesion of the basolateral amygdala, but was not affected by lesion of the central amygdala. In the present study, dentate gyrus LTP was significantly attenuated by basomedial amygdala lesion but not by medial amygdala lesion. These results suggest that, among the amygdaloid nuclei, the basomedial and basolateral nuclei are involved in the modulation of hippocampal plasticity. The roles of the basomedial and basolateral amygdala were further supported by experiments examining the effects of electrical stimulation of these nuclei. High-frequency stimulation of the basomedial amygdala alone did not induce dentate gyrus LTP, but when applied at the same time as tetanic stimulation of the perforant path increased the magnitude of the dentate gyrus LTP. Similarly, high-frequency stimulation of the basolateral amygdala enhanced LTP induced by tetanic stimulation of the perforant path. Furthermore, facilitation of dentate gyrus LTP by basomedial or basolateral amygdala stimulation was observed even in rats lesioned in either amygdala, suggesting that neurons in the basomedial and basolateral amygdala can modulate dentate gyrus LTP independently. Activity-dependent facilitation of hippocampal plasticity by the basomedial and basolateral amygdala may underlie memory processing associated with emotion.  相似文献   
82.
A 58-year-old Japanese woman who had herpes zoster in association with colitis was successfully treated with intravenously administrated acyclovir. Vesicular lesions with red haloes ranged from the left side of her buttock to the left extremity, corresponding to the L4 to S2 dermatomes. Her colitis was considered to have been induced by varicella-zoster virus, based on the facts that the clinical courses were correlated and that the innervation of the affected site of the colon corresponded to an infected dermatome (S2).  相似文献   
83.
84.
Key words  intractable pain - celiac plexus neurolysis - ultrasonography  相似文献   
85.
Transcatheter arterial embolization (TAE) with the concurrent use of caerulein was assessed for the purpose of preventing gallbladder complications often seen after TAE of hepatic carcinoma. Ninety-six cases with primary hepatic carcinoma, who had undergone TAE in the right hepatic arterial region over the past 4 years, were divided into three groups: 22 cases for which embolization was possible on a selective basis by passing the catheter to the peripheral side beyond the bifurcated region of the cystic artery; 40 cases who had undergone TAE in which caerulein was not administered, from the central side of the bifurcated region of the cystic artery; and 34 cases given 20 g caerulein 15–30 min before TAE. A comparison was made using the abdominal pain, pyrexia, rate of leukocytosis and the US findings of the gallbladder as the indices of the gallbladder complications. As a result, it become evident that it was possible to prevent or alleviate gallbladder complications if caerulein were administered before TAE in cases where the embolizing substances were infused in the right hepatic artery from the central side of the bifurcated region of the cystic artery. It was conclusively shown that the gallbladder blood flow decreases if the organ is contracted by caerulein, which in turn causes a decrease in the inflow of the embolizing substances whereby complications are alleviated.  相似文献   
86.
AIMS: p27 is a prominent regulator of cell proliferation by universally inhibiting the cell cycle, while Jun activation domain-binding protein 1 (Jab1), a multifunctional cell signaling protein, contributes to carcinoma progression by degrading p27. In this study, we investigated the expression of these proteins in medullary thyroid carcinoma. METHODS: We immunohistochemically examined Jab1 and p27 expression in 64 medullary thyroid carcinomas. RESULTS: Of the 64 cases examined, decreased p27 expression was observed in 38 cases (59.4%). The p27 expression level was inversely linked to tumour size as well as plasma calcitonin level. Jab1 expression level was generally high, and 46 cases (71.9%) were classified as overexpressing Jab1. The incidence was higher than those in papillary and follicular carcinomas, which were previously reported. Jab1 expression level was inversely linked to that of p27, and all five cases with only cytoplasmic but not nuclear staining of p27 overexpressed Jab1. CONCLUSIONS: These findings suggest that (1) decrease in p27 expression may contribute to local tumour growth; (2) Jab1 expression is related to the progression of medullary carcinoma by decreasing the amount of p27 in the cell and accelerating its degradation; and (3) Jab1 may play a more vital role in the pathogenesis of medullary carcinoma than papillary and follicular carcinomas.  相似文献   
87.
A complete genomic region of 131.2 kb including the swine T-cell receptor alpha/delta constant region (TRAC/TRDC) and joining segments (TRAJ/TRDJ) was sequenced. The structure of this region was strikingly conserved in comparison to that of human or mouse. All of the 61 TRAJ segments detected in the human genomic sequence were detected in the swine sequence and the sequence of the protein binding site of T early alpha, the sequence of the alpha enhancer element and the conserved sequence block between TRAJ3 and TRAJ4 are highly conserved. Insertion of the repetitive sequences that interspersed after the differentiation of the species in mammals such as short interspersed nucleotide elements is markedly suppressed in comparison to other genomic regions, while the composition of the mammalian-wide interspersed sequences is relatively conserved in human and swine. This observation indicates the existence of a highly selective pressure to conserve this genomic region around TRAJ throughout the evolution of mammals.  相似文献   
88.
In diesen Jahhren haben wir einez unehmende Zahl des Beispielsfalls von Pasmozytome auch bei uns in Japan. Und obwohl es noch eine Frage bleibt, ob wir diese Tatsache als wirkliche Zunahme der Krankheit annehmen können, wollen wir hier ihre 7 Fälle berichten, die wir neulich beobachten. Wir bemerken an ihrer klinischen Diagnose zuerst den Schmerz und Anämie, die der Destruktion des Knochensubstanzes entspringen, geringe Leukozytose und die Beschleunigung der Blutsenkungsgeschwindigkeit, es sind aber vor allem der Elektrophorese-Diagram des Serums und die Erscheinung der Paraprotein im Harn, die mit der Krankheit am engsten zusammenhängen. Trotzdem müssen wir darauf achten, daß diese zwei bezeichenden Befunde seltenerweise ausbleiben können (Tbb. 1, 2).  相似文献   
89.
We describe the case of a 40-year-old man whose disease was initially diagnosed as acute myelocytic leukemia. The patient achieved remission with chemotherapy, but relapsed shortly afterwards with an acute T-cell lymphoblastic leukemia. He died of intracranial bleeding. Karyotyping analysis showed a del(9p?) as a common abnormality in the leukemic cells at onset and relapse. Fluorescence in situ hybridization analysis demonstrated allelic loss of the CDKN2A gene in cells from both stages of the disease. At relapse the leukemia cells had additional abnormalities such as add(1)(p36) and del(12)(p11). We postulate that the loss of CDKN2A is involved in leukemogenesis but does not determine the lineage of the leukemic cells. Instead, abnormalities of genes at 1p36, 12p11, or both may be involved in driving a lymphoid phenotype.  相似文献   
90.
The aim of this study is to develop a technical quality evaluation system of electroencephalogram (EEG) recording in order to acquire technically satisfactory EEG records, which may contribute to the accuracy improvement of EEG interpretation. In our developed system, the evaluation of EEG recording comprises the detection of technical artifacts and physiological status, which indicates the recording status objectively. In addition, the caution signals to users are generated in the system according to the undesired status detected. The information displayed to users includes the updated EEG records and instant evaluation results. Two examples of evaluation results are introduced in this paper, illustrating unsatisfactory records and artifact free records, respectively. The experimental results are proposed to verify the effectiveness of the technical quality evaluation of EEG recording. The implementation of the technical quality evaluation of EEG recording is helpful to acquire technically satisfactory EEG records, which may improve the accuracy of results in both the visual and the automatic EEG interpretation, and ease the laborious work of EEG technicians in the recording progress.  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