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   23913篇
  免费   1675篇
  国内免费   1582篇
耳鼻咽喉   130篇
儿科学   269篇
妇产科学   135篇
基础医学   2597篇
口腔科学   392篇
临床医学   3049篇
内科学   760篇
皮肤病学   33篇
神经病学   5567篇
特种医学   942篇
外国民族医学   1篇
外科学   6275篇
综合类   3448篇
现状与发展   3篇
预防医学   414篇
眼科学   1280篇
药学   1038篇
  12篇
中国医学   410篇
肿瘤学   415篇
  2024年   74篇
  2023年   414篇
  2022年   635篇
  2021年   862篇
  2020年   869篇
  2019年   709篇
  2018年   771篇
  2017年   827篇
  2016年   789篇
  2015年   833篇
  2014年   1362篇
  2013年   1718篇
  2012年   1208篇
  2011年   1283篇
  2010年   1196篇
  2009年   1093篇
  2008年   1089篇
  2007年   1192篇
  2006年   1066篇
  2005年   911篇
  2004年   811篇
  2003年   801篇
  2002年   689篇
  2001年   554篇
  2000年   435篇
  1999年   431篇
  1998年   440篇
  1997年   376篇
  1996年   317篇
  1995年   275篇
  1994年   263篇
  1993年   216篇
  1992年   216篇
  1991年   188篇
  1990年   177篇
  1989年   200篇
  1988年   132篇
  1987年   127篇
  1986年   180篇
  1985年   290篇
  1984年   265篇
  1983年   224篇
  1982年   179篇
  1981年   163篇
  1980年   134篇
  1979年   47篇
  1978年   62篇
  1977年   31篇
  1976年   20篇
  1975年   11篇
排序方式: 共有10000条查询结果,搜索用时 253 毫秒
191.
HLA-B27相关的前葡萄膜炎眼后节并发症的临床特点   总被引:1,自引:0,他引:1  
目的探讨HLA—B27阳性的前葡萄膜炎眼后节并发症的临床特点及治疗。方法2002年1月至2005年10月就诊的前葡萄膜炎患者采用流式细胞术进行外周HLA-B27的检测,筛选出71-例82眼HLA-B27阳性前葡萄膜炎患者,分为两组:实验组为眼后节受累的患者24例31眼,对照组为眼后节未受累的患者47例51眼。另有HLA—B27阴性前葡萄膜炎患者74例116眼作参考。所有患者均进行裂隙灯、眼底镜等常规眼科查体,部分行眼底荧光血管造影。分析了HLA—B27相关的前葡萄膜炎眼后节并发症的临床特点。采用x^2检验及t检验进行统计学分析。结果71例82眼HLA—B27阳性前葡萄膜炎中有24例31眼占37.8%出现眼后节并发症者,包括:黄斑囊样水肿12例15眼占48.4%,视乳头水肿7例8眼占25.8%,而玻璃体炎最多见为21例27眼占87.1%,8例10眼占32.3%患者存在两种或两种以上的眼后节表现。74例116眼HLA—B27阴性者有8例12眼占10.3%有眼后节表现。实验组中发生前房成型纤维素渗出31眼中18眼占58.06%和积脓31眼中9眼占29.03%明显高于对照组(前房纤维素渗出51眼中3眼,5.88%,X^2=27.56,P〈0.01;前房积脓51眼中1眼,1.96%,X^2=13.20,P〈0.01);实验组中伴发相关全身性疾病24例中有16例占66.67%的几率高于对照组(47例中有17例,31.66%,X^2=5.94,P〈0.05)。出现眼后节并发症的患者经全身及局部应用糖皮质激素治疗,31眼中有11眼最佳矫正视力≥1.0。结论HLA-B27阳性前葡萄膜炎易出现眼后节并发症,HLA—B27相关的前葡萄膜炎眼后节受累的患者发生相关全身性疾病和前房纤维素渗出与积脓的几率较高。  相似文献   
192.
用自行提纯的人脑和牛脑神经元特异性烯醇酶(NSE)分别免疫家兔,制备兔抗人和抗牛NSE血清(抗NSEh和抗NSEb)。以PAP免疫组织化学染色,系统观察3O只发育出SD大鼠的脑、脊髓与脊神经节。发现NSE最先出现于胚胎15d的脊神经节神经元,随后相继出现于三叉神经节、脊髓、嗅皮质、海马、扣带回和外侧皮质神经元。表明NSE先后出现于周围神经和中枢神经系统,由脊髓向大脑、原始皮质及新皮质发展的顺序,与神经系统发育过程中的头向发展规律相一致。  相似文献   
193.
Twenty patients with AIDS who had intracranial lesions underwent both brain biopsy and cerebro-spinal fluid (CSF) examination to compare histological diagnosis with the polymerase chain reaction (CSF-PCR) for the identification of infectious agents. CSF-PCR was performed for herpes simplex virus, varicella zoster virus, cytomegalovirus (CMV), JC virus (JCV), Epstein-Barr virus (EBV), Toxoplasma gondii and Mycobacterium tuberculosis. A definitive diagnosis was obtained by brain biopsy in 14 patients (2 with astrocytoma, 12 with brain infection). CSF-PCR was positive for EBV DNA in 3 of 3 cases of primary cerebral lymphoma, positive for JCV DNA in 6 of 7 biopsy-proven (and one autopsy-proven) cases of progressive multifocal leukoencephalopathy (PML). CSF-PCR was positive for CMV DNA in one biopsy-proven and one autopsy-proven case of CMV encephalitis (the former also had PML) and positive for M. tuberculosis DNA in one case of tuberculous encephalitis. None of the five toxoplasmic encephalitis cases (one definite, four presumptive) were T. gondii DNA positive. There was close correlation between histology and CSF-PCR for CMV encephalitis, PML and PCL. Antitoxoplasma therapy affected the sensitivity of both histological and CSF-PCR methods. Received: 8 November 1995 Received in revised form: 9 July 1996 Accepted: 19 July 1996  相似文献   
194.
Background: Nausea and vomiting during and after spinal anaesthesia for caesarean section are distressing to the patient. This study was undertaken to evaluate the efficacy and safety of granisetron, droperidol and metoclopramide for the prevention of nausea and vomiting in parturients undergoing caesarean section under spinal anaesthesia.
Methods: In a randomized, double-blind, placebo-controlled trial, 120 patients received granisetron 3 mg, droperidol 1.25 mg, metoclopramide 10 mg or placebo (saline) ( n =30 of each) i. v. immediately after clamping of the foetal umbilical cord. Nausea, vomiting and safety assessments were performed during and after spinal anaesthesia for caesarean section.
Results: The incidence of intraoperative, post-delivery nausea and vomiting was 13%, 17%, 20% and 63% after administration of granisetron, droperidol, metoclopramide and placebo, respectively; the corresponding incidence during 0–3 h after surgery was 7%, 27%, 27% and 43%; the corresponding incidence during 3–24 h after surgery was 7%, 20%, 23% and 37% ( P <0.05; overall Fisher's exact probability test). No clinically important adverse events were observed in any of the groups.
Conclusion: Granisetron is highly effective for preventing nausea and vomiting during and after spinal anaesthesia for caesarean section. Droperidol and metoclopramide are effective for the prevention of intraoperative, post-delivery emesis, but are ineffective for the reduction of the incidence of postoperative emesis.  相似文献   
195.
Intracellular recording was used to study the effect of cyclothiazide, a selective blocker of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor desensitization, on lumbar motoneurons of the rat isolated spinal cord. Cyclothiazide (25 μM) enhanced the responses to AMPA in a tetrodotoxin-insensitive fashion, without affecting those produced by N -methyl-D-aspartate or γ-aminobutyric acid. Excitatory postsynaptic potentials (EPSPs) evoked by dorsal root stimulation were strongly potentiated in amplitude while paired-pulse depression (produced by applying pairs of pulses at 2 s interval) of the EPSP was decreased. In the presence of cyclothiazide the frequency of spontaneous synaptic events was greatly increased and network-driven bursting activity developed with eventual loss of electrical excitability. The present results suggest that pharmacological block of AMPA receptor desensitization led to strong excitation of motoneurons and indicate a physiological role of desensitization in protecting these nerve cells from overactivity.  相似文献   
196.
The development of spinocerebellar projections in the clawed toad, Xenopus laevis, was studied with horseradish peroxidase as an anterograde and retrograde tracer. Early in development cells of origin of spinocerebellar projections were found, contralaterally, in or close to the medial motor column. In older tadpoles ipsilaterally projecting spinal neurons were also labeled from the cerebellum. These are virtually indistinguishable from the large primary motoneurons that occupy a very similar position in the spinal cord. Most of the labeled spinal cells were found in the thoracic spinal cord; they lie halfway between the brachial and lumbar secondary motor columns. Surprisingly, no primary spinocerebellar projection arising from dorsal root spinal ganglion cells could be demonstrated in X. laevis tadpoles and adult toads. Therefore, fibers in the cerebellum that were labeled anterogradely from the spinal cord can be expected to originate exclusively from the secondary spinocerebellar tract cells. These fibers appear to cross the cerebellum in or at the border of the granular layer. The present data suggest that in X. laevis early in the development of the cerebellum a distinct secondary spinocerebellar projection is already present, originating in neurons that can be compared with the "spinal border cells" in mammals. The relative sparseness of this secondary spinocerebellar projection and the apparent absence of primary spinocerebellar afferents probably indicate that spinocerebellar pathways are only of minor importance in X. laevis. The possibility remains, however, that the expansion of the secondary spinocerebellar pathway only starts when metamorphosis has been completed.  相似文献   
197.
背景 退行性腰椎管狭窄症(DLSS)是一种老年多发,严重影响患者正常生活且医疗费用负担较重的疾病。DLSS治疗方法较多,开发高质量的临床实践指南和临床医生应用高质量指南是提高DLSS诊疗水平的重要途径。目的 采用AGREEⅡ及RIGHT评价DLSS相关指南的方法学及报告质量,为DLSS指南制订及报告提供参考依据。方法 计算机检索中国生物医学文献数据库(CBM)、中国知网(CNKI)、万方数据知识服务平台(Wanfang Data)、维普网(VIP)、PubMed,补充检索医脉通数据库(Medlive)、世界卫生组织(WHO)、英国国家临床优化研究所(NICE)、国际指南协作网(GIN)、美国国立指南文库(NGC)和苏格兰院际间协作网(SIGN)等指南库中有关DLSS的临床实践指南、共识或规范,检索时限均为2010-01-01至2022-01-01。由两位评价员独立对纳入文献进行方法学质量及报告质量评价,并在文献中推荐意见等级统一前提下进行比较。结果 共纳入6篇文献,其中4篇指南,2篇共识;1篇指南为中医指南,3篇指南为循证指南。AGREEⅡ评价结果显示纳入6篇文献的实际总得分/总最高可...  相似文献   
198.
脊柱结核是一种常见的肺外结核病。近年来,随着脊柱结核患者逐年增多,不典型脊柱结核患者亦逐渐增多,而不典型脊柱结核诊断较为困难,需要与一般细菌感染、肿瘤以及非结核分枝杆菌感染相鉴别。基因诊断技术是一项诊断脊柱结核的重要工具,对临床不典型脊柱结核的诊断有较高价值。本文将对脊柱结核的流行现状、诊断及基因诊断技术进行综述,以帮助临床工作者对脊柱结核做出更加准确的诊断。  相似文献   
199.
The afferent thalamic connections to cortical fields important for control of head movement in space were analysed by intracortical retrograde tracer injections. The proprioceptive/vestibular area 3aV, the neck-trunk region of area 3a, receives two thirds of its thalamic projections from the oral and superior ventroposterior nucleus (VPO/VPS), which is considered as the proprioceptive relay of the ventroposterior complex (Kaas et al., J. Comp. Neurol. 226:211-240, 1984). The parieto-insular vestibular cortex (PIVC, area retroinsularis, Ri) receives its main thalamic input from posterior parts of the ventroposterior complex and from the medial pulvinar. Anatomical evidence is presented that the posterior region of the ventroposterior complex is a special compartment within this principal somatosensory relay complex. The parietotemporal association area T3, mainly involved in visual-optokinetic signal processing, receives a substantial input from the medial, the lateral, and the inferior pulvinar. Dual tracer experiments revealed that about 5% of the thalamic neurons projecting to 3aV were spatially intermingled with neurons projecting to areas PIVC or T3. This spatial intermingling was distributed over small but numerous, circumscribed thalamic regions, called "common patches," which were found mainly in the intralaminar nuclei, the posterior group of thalamic nuclei, and the caudal parts of the ventroposterior complex. The "common patches" may indicate a functional coupling of area 3aV with the PIVC or area T3 on the thalamic level. In control experiments thalamic projections to the granular insula Ig and the anterior part of area 7, two cerebral structures connected with the vestibular cortical areas, were studied. Some overlap in the thalamic relay structures projecting to these areas with those projecting to the vestibular cortices was found. A quantitative evaluation of thalamic regions projecting to different cortical structures was performed by constructing so-called "thalamograms." A scheme was developed that describes the afferent thalamic connections by which vestibular, visual-optokinetic, and proprioceptive signals reach the vestibular cortical areas PIVC and 3aV.  相似文献   
200.
In intact cats, it is generally considered that the lateral posterior-pulvinar complex (LP-pulvinar) does not receive direct retinal terminals, with the exception of the retino-recipient zone known as the geniculate wing. There is, however, some evidence that early lesions of the visual cortex can occasionally induce the formation of novel retinal projections to the LP nucleus. Given the importance of knowing the connectivity pattern of the LP-pulvinar complex in intact and lesioned animals, we used the B fragment of cholera toxin, a sensitive anterograde tracer, to reinvestigate the retinal projections to the LP-pulvinar in normal cats and in cats with early unilateral lesions of the visual cortex (areas 17 and 18). Immunohistochemical localization of the toxin was performed to show the distribution and morphology of retinofugal terminals. A direct bilateral but predominantly contralateral retinal projection reached the caudal portion of LPl and LPm in the form of patches located mainly along its dorsomedial surface and many scattered terminals. The distribution of retinal projections to LP-pulvinar in intact and operated cats did not differ. Contrary to what had been previously reported, we found no evidence for lesion-induced sprouting of retinal axons in these higher-order thalamic nuclei. Retinal input to the LP-pulvinar might modulate visual responses driven by primary visual cortex or superior colliculus.  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