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   10377篇
  免费   632篇
  国内免费   93篇
耳鼻咽喉   70篇
儿科学   274篇
妇产科学   276篇
基础医学   1415篇
口腔科学   150篇
临床医学   804篇
内科学   2655篇
皮肤病学   131篇
神经病学   1470篇
特种医学   416篇
外科学   1024篇
综合类   17篇
一般理论   3篇
预防医学   479篇
眼科学   129篇
药学   811篇
中国医学   10篇
肿瘤学   968篇
  2024年   26篇
  2023年   169篇
  2022年   292篇
  2021年   503篇
  2020年   268篇
  2019年   387篇
  2018年   421篇
  2017年   317篇
  2016年   373篇
  2015年   388篇
  2014年   556篇
  2013年   643篇
  2012年   843篇
  2011年   867篇
  2010年   499篇
  2009年   455篇
  2008年   649篇
  2007年   591篇
  2006年   585篇
  2005年   511篇
  2004年   389篇
  2003年   318篇
  2002年   291篇
  2001年   65篇
  2000年   62篇
  1999年   76篇
  1998年   51篇
  1997年   41篇
  1996年   46篇
  1995年   29篇
  1994年   31篇
  1993年   18篇
  1992年   26篇
  1991年   38篇
  1990年   33篇
  1989年   31篇
  1988年   36篇
  1987年   26篇
  1986年   24篇
  1985年   20篇
  1984年   17篇
  1983年   9篇
  1982年   7篇
  1981年   8篇
  1980年   4篇
  1979年   22篇
  1978年   4篇
  1976年   6篇
  1973年   5篇
  1966年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
We report a case of leishmaniasis localized to the upper lip in a 77-year-old Italian man. The disease was characterized by a severe swelling which involved the right side of the upper lip. The swelling was slightly erythematous with crusts and scaling. Consistency was parenchymatous-hard. The lesion was asymptomatic. Histopathologic examination showed an inflammatory infiltrate consisting of lymphocytes, histiocytes, and plasma cells. Several Leishmania spp. amastigotes were observed in the cytoplasm of macrophages. Cultural examination on Novy-MacNeal-Nicolle medium was positive for Leishmania spp. Polymerase chain reaction was positive for Leishmania infantum. The patient was treated with i.m. N-methylglucamine antimonate, with complete remission in approximately 6 weeks. During follow-up of 9 months, no relapses were observed.  相似文献   
32.

Aim  

The aim of the present study was to collect and compare cases of drug-induced PML in order to contribute to the debate about the role of the underlying diseases and/or drug immunosuppression in PML occurrence.  相似文献   
33.
The hepatitis B virus (HBV) and hepatitis Delta virus (HDV) infection rates were estimated in patients attending a venereal disease outpatient clinic: 759 heterosexuals and 154 homosexual-bisexual men. The anti-HBC prevalence was higher in homo-bisexual men (68.8 per 100) than in heterosexuals (41.8 per 100), whereas HBsAg was roughly the same in the two groups (about 6 per 100). The anti-HBc prevalence rate among heterosexuals was higher than that estimated in hospital personnel from the same geographical area. A positive association between anti-HBc prevalence and present or past sexually transmitted diseases (STD) was found among homo-bisexual men. Anti-HBc was also positively associated with herpes simplex type 2 antibodies in both heterosexuals and homo-bisexual men. These data are consistent with the hypothesis that sexual behavior also plays a role in the spread of infection among heterosexuals. Ten of the 46 HBsAg-positive subjects were anti-HDV positive: 6 of the 36 heterosexuals and 4 of the 10 homosexuals. All HDV-positive subjects had present or past STDs. These findings suggest sexual transmission of HDV infection.  相似文献   
34.
Two hundred HIV-positive subjects were surveyed to determine their periodontal health status. Particular attention was given to the occurrence of a severe and rapidly progressing form of periodontal disease designated "HIV-associated periodontitis", which has been reported as being unique to AIDS patients. Among the subjects comprising the cohort, 85 subjects had good gingival health, 59 subjects exhibited gingivitis, 49 cases of adult periodontitis were observed, 5 subjects presented with advance adult periodontitis, and 2 cases of necrotizing ulcerative periodontitis (NUP) were found within the group. The periodontitis of the patients in this survey did not have unique or pathognomonic characteristics which could set their periodontal disease apart from the periodontal disease seen in HIV negative population.  相似文献   
35.
Patients with agammaglobulinemia may excrete enteroviruses, including vaccine-derived poliovirus, for prolonged periods of time. This poses a risk to the patients but it also may pose a risk to the population after eradication of poliovirus and the cessation of routine vaccination. To assess this risk, a pilot study was performed to identify potential poliovirus long-term excretors in a cohort of 38 patients with a definite/presumptive diagnosis of X-linked agammaglobulinemia (XLA). Stool samples were analyzed to detect any polio or other enteroviruses replicating in the gut and neutralizing antibodies against polioviruses were measured in the sera. No viruses were isolated from the stool samples and most sera had neutralizing antibody levels against all three poliovirus serotypes considered by the WHO to be protective in immunocompetent individuals. This suggests that long-term excretion of enteroviruses in patients with agammaglobulinemia is relatively uncommon.  相似文献   
36.
Bilateral intrathalamic microinjections of nanogram amounts (5–50 ng) of muscimol, a γ-aminobutyrate (GABA) receptor agonist, elicited catalepsy in rats. Like neuroleptic-treated rats, those injected with muscimol in the thalamus remained suspended on a vertical grid but, unlike opioid-treated rats, they failed to remain horizontal on two book-holders. The righting reflex was present, while ptosis was absent. The areas with the highest sensitivity to the cataleptogenic effects of muscimol were the ventromedial and ventral-anterior nuclei of the thalamus. These thalamic areas were also characterized by the shortest latency for the induction of catalepsy. Injection of up to 50 ng of muscimol into the caudate, globus pallidus or entopeduncular nucleus failed to produce catalepsy. Catalepsy was also obtained after intrathalamic microinjection of other GABA analogs, such as 3-aminopropanesulphonic and imidazolacetic acid, which are known to be potent GABA receptor agonists, and β-p-chlorophenyl-GABA , a compound which has GABA mimetic activity. The catalepsy produced by 10 ng of muscimol was reversed by an intrathalamic microinjection of picrotoxin, a GABA receptor antagonist. Muscimol-induced catalepsy, unlike neuroleptic-induced catalepsy, was not reversed by systemic administration of high doses of apomorphine, a dopamine receptor agonist, or of scopolamine, a muscarine antagonist, or by intranigral injection of muscimol, and was not prevented by kainic acid-induced lesions of the striatum or of the nigra. Vice versa, injection of cataleptogenic doses of muscimol in the thalamus failed to prevent the stereotyped gnawing produced by systemic apomorphine or intranigral muscimol. Therefore, in these animals, catalepsy and stereotyped gnawing coexisted. The unilateral intrathalamic microinjection of muscimol resulted in a postural asymmetry consisting of turning towards the injected side. This ipsilateral posturing was converted into an ipsilateral circling by systemic administration of apomorphine.The results indicate that thalamic GABAergic mechanisms play an important role in the regulation of posture and in the mediation of certain motor responses arising in the striatum.  相似文献   
37.
Pain in individuals with RASopathies is a neglected topic in literature. In this article, we assessed prevalence and profile of pain in a sample of 80 individuals affected by RASopathies. The study sample included individuals with Noonan syndrome (N = 42), Costello syndrome (N = 17), and cardio‐facio‐cutaneous syndrome (N = 21). A set of standardized questionnaires and scales were administered (VAS/numeric scale, r‐FLACC, Wang‐Baker scale, NPSI, BPI, NCCPC‐R) to detect and characterize acute and chronic pain and to study the influence of pain on quality of life (PEDs‐QL, SF‐36) and sleeping patterns (SDSC); revision of past medical history and multisystemic evaluation was provided. Available clinical data were correlated to the presence of pain. High prevalence of acute (44%) and chronic (61%) pain was documented in the examined sample. Due to age and intellectual disability, acute pain was localized in 18/35 individuals and chronic pain in 33/49. Muscle‐skeletal and abdominal pain was more frequently reported. The intensity of acute and chronic pain interfered with daily activities in 1/3 of the sample. Pain negatively impacted on QoL and sleeping patterns. This work documents that pain is highly prevalent in RASopathies. Future studies including subjective and objective measures of pain are required to discriminate a somatosensory abnormality from an abnormal elaboration of painful stimuli at a central level.  相似文献   
38.
Potocki–Lupski syndrome is a condition mainly characterized by infantile hypotonia, developmental delay/intellectual disability (DD/ID), and congenital anomalies, caused by duplications of the 17p11.2 region, encompassing RAI1 gene. Its clinical presentation is extremely variable, especially for what concerns the cognitive level and the behavioral phenotype. Such aspects, as well as the dysmorphic/malformative ones, have been covered by previous studies; otherwise neurological features have never been systematically described. In order to delineate the neurological phenotype of Potocki–Lupski Syndrome, we collect an 8‐patients cohort. Developmental milestones are delayed and a mild to moderate cognitive impairment is present in all patients, variably associated with features of autism spectrum disorder, behavioral disturb, and sleep disturb. Hypotonia appears a less frequent finding than what previously reported, while motor clumsiness/coordination impairment is frequent. EGG registration demonstrated a common pattern with excess of diffuse rhythmic activity in sleep phases or while the patient is falling asleep. Brain MRI did not reveal common anomalies, although unspecific white matter changes may be present. We discuss such findings and compare them to literature data, offering an overview on the neurological and cognitive‐behavioral presentation of the syndrome.  相似文献   
39.
BACKGROUND: The importance of the standardisation of nucleic acid amplification technology (NAT) assays for the detection of hepatitis C virus RNA is well known today, as many studies carried out in different European countries attest. The results of a previous study performed in Italy (J. Clin. Virol. 1 (2003) 83) by the Italian Society of Clinical Microbiology (AMCLI) showed that the use of external reference standards and of multicentre collaborative studies significantly improves laboratory performance for the qualitative evaluation of HCV RNA. OBJECTIVES: the AMCLI organised a new study on the standardisation of both the qualitative and the quantitative evaluation of HCV RNA with NAT in order to improve the implementation of the diagnostic methods for HCV RNA detection. STUDY DESIGN: seventeen diagnostic centres of major Italian Hospitals participated in this quality control study. The study consisted of testing three panels, each made up of 10 coded samples including negative and positive samples. Positive samples contained four levels of HCV RNA (genotype 1). RESULTS AND CONCLUSION: Seven out of 510 qualitative results obtained were incorrect (1.4%), two false negative and five false positive. The results gave a sensitivity of 99.5% and a specificity of 95.8%. Regarding quantitative tests, the geometric mean (GM) and standard deviation (S.D.) could be calculated only for the three highest HCV RNA levels. The percentage of results within the range of GM +/- 0.5 log(10) varied from 91% to 100%. Some laboratories had some difficulty in the exact quantification of the lowest (3.00 log IU/ml) as well as of the highest viral levels (6.35 log IU/ml) values, very near to the limits of the dynamic range of the assays. The comparison of the results of this study with that previously carried out one confirms that a regular participation in external quality assessment (EQA) assures the achievement of a high proficiency level in the diagnosis of HCV infection.  相似文献   
40.
Pneumocystis carinii f. sp. hominis isolates from 207 clinical specimens from nine countries were typed based on nucleotide sequence variations in the internal transcribed spacer regions I and II (ITS1 and ITS2, respectively) of rRNA genes. The number of ITS1 nucleotides has been revised from the previously reported 157 bp to 161 bp. Likewise, the number of ITS2 nucleotides has been changed from 177 to 192 bp. The number of ITS1 sequence types has increased from 2 to 15, and that of ITS2 has increased from 3 to 14. The 15 ITS1 sequence types are designated types A through O, and the 14 ITS2 types are named types a through n. A total of 59 types of P. carinii f. sp. hominis were found in this study.  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