全文获取类型
收费全文 | 22217篇 |
免费 | 1220篇 |
国内免费 | 188篇 |
专业分类
耳鼻咽喉 | 243篇 |
儿科学 | 493篇 |
妇产科学 | 492篇 |
基础医学 | 2652篇 |
口腔科学 | 765篇 |
临床医学 | 1680篇 |
内科学 | 5436篇 |
皮肤病学 | 302篇 |
神经病学 | 2326篇 |
特种医学 | 865篇 |
外科学 | 3455篇 |
综合类 | 63篇 |
一般理论 | 2篇 |
预防医学 | 1253篇 |
眼科学 | 555篇 |
药学 | 1282篇 |
中国医学 | 23篇 |
肿瘤学 | 1738篇 |
出版年
2023年 | 214篇 |
2022年 | 509篇 |
2021年 | 811篇 |
2020年 | 470篇 |
2019年 | 668篇 |
2018年 | 719篇 |
2017年 | 562篇 |
2016年 | 598篇 |
2015年 | 678篇 |
2014年 | 868篇 |
2013年 | 1148篇 |
2012年 | 1706篇 |
2011年 | 1779篇 |
2010年 | 934篇 |
2009年 | 879篇 |
2008年 | 1341篇 |
2007年 | 1354篇 |
2006年 | 1237篇 |
2005年 | 1206篇 |
2004年 | 1198篇 |
2003年 | 971篇 |
2002年 | 908篇 |
2001年 | 294篇 |
2000年 | 225篇 |
1999年 | 233篇 |
1998年 | 192篇 |
1997年 | 166篇 |
1996年 | 152篇 |
1995年 | 106篇 |
1994年 | 100篇 |
1993年 | 68篇 |
1992年 | 124篇 |
1991年 | 101篇 |
1990年 | 107篇 |
1989年 | 107篇 |
1988年 | 107篇 |
1987年 | 73篇 |
1986年 | 82篇 |
1985年 | 65篇 |
1984年 | 70篇 |
1983年 | 45篇 |
1982年 | 40篇 |
1981年 | 30篇 |
1980年 | 29篇 |
1979年 | 32篇 |
1978年 | 36篇 |
1976年 | 25篇 |
1975年 | 23篇 |
1974年 | 24篇 |
1973年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Carla Ghelardini Alessandro Quattrone Nicoletta Galeotti Silvia Livi Grazia Banchelli Laura Raimondi Renato Pirisino 《Neuropsychopharmacology》2003,28(6):1096-1105
Amphetamine (AMPH) is an indirect sympathomimetic compound classified as a substrate-type releaser that distinguishes it from other stimulants that act as uptake 1 blockers, such as cocaine (COC). In mammals, AMPH elicits central stimulation, hypermotility, anorexia, analgesia and analeptic activity, mainly through the increase of extracellular brain dopamine (DA). The inversion of vesicular transporters and/or intravesicular alkalinization is assumed to have a role in AMPH-induced exocytosis. However, the action mechanism of this compound has not yet been completely clarified. Recent evidence on the action of AMPHs indicates potassium channel-blocking properties in peripheral tissues. We investigated the possible involvement of a Shaker-like Kv1.1 channel subtype in the central effects of AMPH, using an antisense oligodeoxyribonucleotide (aODN) that specifically and reversibly inhibits the expression of these channels in the brain. The effect of aODN pretreatments was studied by evaluating the modification of behavioral effects induced in mice through the intracerebroventricular administration of AMPH, COC, or other compounds. The aODN in mice almost completely blocked the stimulatory effects of AMPH and other releasers but was ineffective in reducing the central activity of COC. In aODN-pretreated rats a strong reduction of the AMPH, but not of the COC-stimulated DA efflux from nucleus accumbens was observed. Our results suggest that the stimulant effects of AMPH and chemically related compounds, but not COC, require the presence of functionally active Kv1.1 channels in the brain. 相似文献
82.
Mario Zama Simona Gallo Luigino Santecchia Ettore Bertozzi Antonio Zaccara Alessandro Trucchi Antonella Nahom Pietro Bagolan Cosmoferruccio De Stefano 《British journal of plastic surgery》2004,57(8):749-753
Omphalocele is the most common congenital defect of the abdominal wall. Mortality rate is between 20 and 70% and early closure of the abdominal wall, within 10 days of life, is vital to the successful outcome of the surgical treatment. The authors describe the use of two bipedicled flaps of abdominal skin to correct the defect of the midline as soon as the reduction of all viscera has been accomplished. 相似文献
83.
Flavio Masi Benedetta Leggio Giulio Nanni Simona Scheggi M Graziella De Montis Alessandro Tagliamonte Silvia Grappi Carla Gambarana 《Neuropsychopharmacology》2003,28(4):683-693
Long-term acetyl-L-carnitine (ALCAR) administration prevents the development of escape deficit produced by acute exposure to unavoidable stress. However, it does not revert the escape deficit sustained by chronic stress exposure. Rats exposed to chronic stress show a low dopamine (DA) output in the nucleus accumbens shell (NAcS) and do not acquire an appetitive behavior sustained by the earning of vanilla sugar (VS) made contingent on the choice of one of the two divergent arms of a Y-maze (VS-sustained appetitive behavior, VAB), while control rats consistently do. The present study shows that ALCAR treatment in rats exposed to a 7-day stress protocol prevented a decrease in DA output in the NAcS and medial prefrontal cortex (mPFC) of rats, and that it strengthened the DA response to VS consummation in the same two areas. Moreover, rats treated with long-term ALCAR or exposed to chronic stress while treated with ALCAR acquired VAB as efficiently as control rats. Moreover, VAB acquisition in stressed rats treated with ALCAR coincided with the reversal of the deficits in escape and in dopaminergic transmission in the NAcS. Thus, repeated ALCAR treatment preserved the DA response to VS in chronically stressed rats and this effect appeared to be predictive of the rat's competence to acquire VAB. 相似文献
84.
β-N-Acetylhexosaminadases in human cerebrospinal fluid and serum of patients with multiple sclerosis
Alessandro Datti Carla Emiliani Giuseppe Capocchi Aldo Orlacchio 《Clinica chimica acta; international journal of clinical chemistry》1991,200(2-3)
β-N-Acetylhexosaminidase activity and isoenzyme have been investigated in normal human cerebrospinal fluid and that of patients with multiple sclerosis. β-N-acetylhexosaminidase activity in normal cerebrospinal fluids has been resolved into five components. The major component was in a form that eluted from DEAE cellulose at the same salt concentration as hexosaminidase As, the isoenzyme previously identified in human serum. Cerebrospinal fluid from patients exhibited a different isoenzyme profile, showing a remarkable increase in a form having a pI which was more acidic than that of As. These changes have a potential use in the diagnosis and further biochemical characterization of multiple sclerosis. 相似文献
85.
Deletion of the Major Proteolytic Site of the Helicobacter pylori Cytotoxin Does Not Influence Toxin Activity but Favors Assembly of the Toxin into Hexameric Structures 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Daniela Burroni Pietro Lupetti Cristina Pagliaccia Jean Marc Reyrat Romano Dallai Rino Rappuoli John L. Telford 《Infection and immunity》1998,66(11):5547-5550
The Helicobacter pylori cytotoxin is proteolytically cleaved at a flexible hydrophilic loop into two subunits. Deletion of the loop sequences had no effect on biological activity of the toxin in the HeLa cell vacuolation assay but favored the organization of the protein into hexameric rather than heptameric structures. 相似文献
86.
Paolo Ambrosetto Stefano Zucchini Alessandro Cicognani Emanuele Cacciari 《Pediatric radiology》1998,28(5):288-289
A girl with Diamond-Blackfan syndrome and hypopituitarism was suspected of having pituitary haemosiderosis because of the
clinical picture and the long history of blood transfusions. On T1-weighted MR images the pituitary exhibited a markedly hypointense
anterior lobe (mimicking the empty sella), suggesting iron deposition, while on T2W MRI the low signal of the pituitary was
surrounded by the high signal of the CSF. MR may be considered the examination of choice for detecting iron overload in the
pituitary.
Received: 10 November 1997 Accepted: 21 November 1997 相似文献
87.
Emanuele Lezoche M.D. Alessandro M. Paganini M.D. Ph.D. Francesco Carlei M.D. Francesco Feliciotti M.D. Davide Lomanto M.D. Ph.D. Mario Guerrieri M.D. 《World journal of surgery》1996,20(5):535-542
n
= 2), port site infection (
n
= 2), and subumbilical hematoma (
n
= 1). Major morbidity was bile leakage from the cystic duct stump in two cases due to clips or transcystic duct drainage displacement,
respectively. One elderly, high risk patient died after being referred for several failed attempts of endoscopic clearance;
she died from cardiogenic shock 3 days after successful laparoscopic treatment. Laparoscopic CBD exploration is feasible and
safe in most patients, with short-term results that compare favorably with the results of sequential ES/LC reported in the
literature. 相似文献
88.
Laura Santambrogio Maria Lipartiti Alessandro Bruni Roberto Dal Toso 《Journal of neuroimmunology》1993,45(1-2)
The presence of functional dopamine receptors on differentiated cells of the mammalian immune system is still under discussion. This study has utilized (-)-[3H]sulpride as a ligand to detect the presence of recognition sites of the dopamine D2 receptor family on human T- and B-lymphocytes. The (-)-[3H]sulpiride binding was of high affinity (Kd 0.9 nM ± 0.2 nM, specific, saturable (Bmax 10.2 ± 1.4 fmol/106 cells) and reversible. The pharmacological characterization of the recognition site suggests, similarities mainly with the D2 and D4 rather than D3 subtype of dopamine receptor. Furthermore, dopamine treatment was able to reduce the intracellular cAMP levels of lymphocytes stimulated with forskolin, thus suggesting a potential functional significance of this dopamine receptor in mediating neural-immune interactions. 相似文献
89.
A difficult physician-patient relationship can have significant consequences for both the physician and the patient. Difficult relationships can lead to frustrating, dissatisfying, adversarial and expensive medical care. The difficult relationship is often a consequence of a breakdown in communication between physician and patient. Specific causes include technical communication barriers, difficulty in discussing certain topics, unmet or violated norms and expectations (both the physician's and the patient's) and a mismatch between the physician's and the patient's personality styles. Management goals for the difficult relationship include maintaining professional self-esteem, maintaining physician-patient continuity, minimizing the "medicalization" of the problem by limiting the use of tests and procedures, and minimizing hospitalization and referral. It is also important to remember that although the relationship may continue to be frustrating or conflictual, it can be effectively managed with appropriate strategies. 相似文献
90.