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   18956篇
  免费   1091篇
  国内免费   51篇
耳鼻咽喉   152篇
儿科学   486篇
妇产科学   384篇
基础医学   2543篇
口腔科学   637篇
临床医学   1338篇
内科学   4970篇
皮肤病学   468篇
神经病学   1612篇
特种医学   427篇
外科学   2584篇
综合类   119篇
一般理论   8篇
预防医学   1332篇
眼科学   644篇
药学   932篇
中国医学   69篇
肿瘤学   1393篇
  2023年   154篇
  2022年   276篇
  2021年   652篇
  2020年   361篇
  2019年   520篇
  2018年   637篇
  2017年   400篇
  2016年   417篇
  2015年   560篇
  2014年   668篇
  2013年   898篇
  2012年   1446篇
  2011年   1545篇
  2010年   829篇
  2009年   786篇
  2008年   1349篇
  2007年   1379篇
  2006年   1328篇
  2005年   1180篇
  2004年   1008篇
  2003年   981篇
  2002年   908篇
  2001年   142篇
  2000年   107篇
  1999年   143篇
  1998年   145篇
  1997年   116篇
  1996年   111篇
  1995年   103篇
  1994年   103篇
  1993年   81篇
  1992年   48篇
  1991年   53篇
  1990年   39篇
  1989年   37篇
  1988年   33篇
  1987年   37篇
  1986年   29篇
  1985年   31篇
  1984年   43篇
  1983年   34篇
  1982年   36篇
  1981年   51篇
  1980年   23篇
  1979年   25篇
  1978年   32篇
  1977年   26篇
  1976年   29篇
  1973年   20篇
  1969年   17篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
The cognitive effects of active and sham repetitive transcranial magnetic stimulation (rTMS) were examined in 19 middle-aged and elderly patients with refractory depression. Patients received either active (n = 9) or sham (n = 10) rTMS targeted at the anterior portion of the left middle frontal gyrus. Patients in the active rTMS group improved significantly on a test of cognitive flexibility and conceptual tracking (Trail Making Test-B).  相似文献   
992.
We evaluated the fractures of the lumbar and sacral vertebral limbus by disc impingement at the peripheral ring apophysis in 23 adults associated with trauma in 16 of them. Lumbalgia, radicular pain and narrow canal symptoms are the presenting forms of this underdiagnosed pathology. CT is the best method of examination, while plain roentgenograms and MR are usually negative. Accurate diagnosis and surgical technique with larger exposure are needed to resect the fractured fragments and protruded disc material for decompressing the roots and the dural sac. Our results were very good on the majority of cases.  相似文献   
993.
Following social disruption (SDR) stress in male mice, corticosterone resistance of splenocytes was accompanied by enhanced LPS-stimulated interleukin (IL)-6 secretion. The present study examined the role of IL-6 in the development of corticosterone resistance. Addition of IL-6 to control splenocyte cultures did not induce corticosterone resistance. SDR also elevated IL-6 in plasma and liver, but not in spleen. IL-6 deficient mice that were exposed to SDR developed glucocorticoid resistance despite the absence of systemic IL-6. These findings suggest that although SDR enhanced IL-6 responses, IL-6 was not essential for the development of stress-induced splenocyte corticosterone resistance.  相似文献   
994.
995.
BACKGROUND: The proportion of women among persons with sexually transmitted disease (STD)/AIDS in Brazil is increasing rapidly, and studies are needed to understand risk behaviors. GOAL: The goal of this study was to identify factors associated with risk behaviors for acquiring STD/AIDS among women aged 15 to 49 years in Pelotas, Brazil. STUDY DESIGN: A representative sample of women was surveyed by means of interviewer-administered and self-administered confidential questionnaires. Of the women we sought to include, 3.5% refused and 1543 participated. RESULTS: Risk behaviors included nonuse of condoms (72%); first intercourse before the age of 18 years (47%); use of drugs or alcohol by the partner (14%) or by the woman (7%); multiple partners (7%); and anal sex (3%). The risk score was significantly associated with being younger than age 30 years, having <5 years of schooling, being divorced or separated, and being a smoker. CONCLUSION: Preventive strategies should prioritize efforts toward young women, those with little schooling, smokers, and those who are divorced or separated.  相似文献   
996.
To outline through clinical-laboratorial analysis a profile of schistosomiasis of the spinal cord (SSC) that contributes to the diagnosis and treatment of this disease. 80 patients were studied (59 prospectively), and epidemiological, clinical,laboratorial, treatment and outcome data extracted. In 79 patients the diagnosis was presumptive and obeyed rigorous criteria. There was a predominance of male sex (68.7%), age group from 21 to 40 years (63.7%), Northeasterners (85%), building construction workers (31.2%), previous abdominal effort (57.5%), subacute beginning (61.2%), myeloradiculitis form and lesion in conus and cauda equina (72.5%). Cerebral spinal fluid showed lymphomononuclear pleocytosis and protein increase in 100% of the cases as well as gamma globulin in 76.5%, positiveness of immunofluorescence reaction and/or ELISA for schistosomiasis in 100% of the cases with average titles of 1/16 and 61 u/dl, respectively. Corticosteroids and antischistosomal drugs were given to all patients with a satisfactory outcome in 80% of the cases. We emphasize the importance of a precocious treatment to avoid irreversible deficits such as paraplegia or sexual impotence.  相似文献   
997.
The histological, connectional, and ultrastructural characteristics of a peculiar neuron type in the rat anterior commissure (AC) are described. Since these cells are located among the axonal fascicles of the rostral and caudal parts of the AC, they are termed interfascicular neurons (IFN). In rapid-Golgi sections IFNs appeared in two forms: internuncial (i.e., short axon) and projection neurons (i.e., long axon). The axon of the internuncial neurons terminates upon neighboring IFNs. The projection neurons give rise to an axon which is either incorporated into commissural fibers or ramifies into 12-26 collaterals running laterally in opposite directions along commissural axons. Immunohistochemistry to microtubule-associated protein 2 combined with confocal microscopy showed that IFNs display short varicose dendrites which remain confined to the domain of the AC. The neuronal nature of IFNs was confirmed with the electron microscope on the basis of distinctive organelles and the presence of synaptic inputs. Small areas of neuropil surround some IFNs. These areas are composed of proximal dendrites, terminal axons, axo-shaft and axo-spinous synapses. Because IFNs with their afferents and efferents constitute sufficient elements to integrate neural inputs, it is proposed that they may be involved in processing nerve impulses proceeding from the bilateral cerebral structures connected by the AC.  相似文献   
998.
In this work we studied the presence of histamine H(1) receptors in the rat dorsal raphe nucleus (DRN) and the effect of their activation on the activity of presumed serotonergic DRN neurones. [(3)H]-Mepyramine bound to DRN membranes with best-fit values of 107+/-13 fmol/mg protein for maximum binding (B(max)) and 1.2+/-0.4 nM for the equilibrium dissociation constant (K(d)). In DRN slices labelled with [(3)H]-inositol and in the presence of 10 mM LiCl, histamine stimulated the accumulation of [(3)H]-inositol phosphates ([(3)H]-IPs) with maximum effect 172+/-6% of basal and EC(50) 3.2+/-1.3 microM. [(3)H]-IPs accumulation induced by 100 microM histamine (162+/-5% of basal) was markedly, but not fully blocked by the selective H(1) antagonist mepyramine (300 nM; 64+/-6% inhibition). The simultaneous addition of mepyramine and the selective H(2) antagonist ranitidine (10 microM) abolished histamine-induced [(3)H]-IPs accumulation. The presence of H(2) receptors was confirmed by [(3)H]-tiotidine binding and by the determination of histamine-induced [(3)H]-cyclic AMP formation. Extracellular single-unit recording in brain stem slices showed that the exposure to histamine resulted in a marked increase in the firing rate of DRN presumed serotonergic neurones (471+/-10% of basal), that was dependent on the concentration of the agonist (EC(50) 4.5+/-0.3 microM). The action of histamine was not affected by the H(2) antagonist tiotidine (2 microM) but was fully prevented by 1 microM mepyramine. Taken together, our results indicate that histamine modulates the firing of DRN presumed serotonergic neurones through the activation of H(1) receptors coupled to phosphonositide hydrolysis.  相似文献   
999.
Medical complications after stroke are an important problem not only for patients, but also for their families and the clinicians who take care of them, thus representing a major public health problem. Among medical illnessess complicating stroke, in the last several years much efforts has been directed to determine the role of affective disorders. Although depression coexisting with stroke has been shown to increase levels of functional disability and reduce the effectiveness of rehabilitation, we still have much to learn about the clinical interface between such disorders. This review focuses on the data concerning the potential relationship between depression and cerebrovascular disease (CVD) and the emerging insights which may be relevant to provide directions for the development of novel research strategies on the pathogenesis and treatment of post-stroke depression.  相似文献   
1000.
The IPL nude rat, derived by spontaneous mutation from the Sprague-Dawley strain, presents alterations in the prolactin synthesis and secretion due to an increased dopaminergic inhibition. However, there are no reports concerned to central dopamine activity. The corpus striatum is a brain area involved in the development of stereotyped behavior after the activation of mesolimbic and/or nigro-striatal dopamine pathways. In order to identify possible mesolimbic and/or nigro-striatal dysfunctions in the IPL nude rat, we study the spontaneous oral behaviors and the effects of apomorphine-induced dopaminergic activation on stereotyped behavior and neurochemical changes. Males from both strains were injected with saline or apomorphine (2 and 5 mg/kgs.c.) and evaluated during 30 min in a stereotypes oral tests. The corpus striatum and nucleus accumbens were used to measure dopamine (DA), 3,4-dihydroxyphenylalanine (DOPA) and 3,4-dihydroxyphenylacetic acid (DOPAC) by HPLC. The concentrations were expressed as synthesis rate (DA/DOPA) and turnover rate (DOPAC/DA). We observed that the spontaneous gnaw movements were significantly different between the untreated IPL nude and Sprague-Dawley (SD) rats. Apomophine injection decreased the amount of stereotyped gnawing in IPL nude rats at the two doses used, but it induced an increase in SD rats. Apomorphine also caused an enhancement in the number of biting and sniffing without modifying the licking behavior. In addition, modifications of the dopaminergic activity were also observed. Synthesis rate in the striatum of IPL nude rats was higher than in SD rats after the injection of saline. Apomorphine caused a reduction of the synthesis rate in both strains. Turnover rate was significantly lower in the striatum of IPL nude rats than in the SD rats injected with saline. Apomorphine caused an increase in the turnover rate in both strains. Contrary to observed in the striatum, the 2 mg/kg dose of apomorphine caused a significant increase in the DA synthesis rate in nucleus accumbens, while 5 mg/kg decrease it in both strains. The DA turnover rate in the same area was lower in IPL nude than in SD rats after saline injection. Apomorphine enhances the DA turnover rate in both strains. We conclude that the modifications of the oral spontaneous and induced stereotypical patterns observed in the IPL nude rats could be related to the differential responses in dopaminergic activity in the two brain areas examined.  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