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   163012篇
  免费   10414篇
  国内免费   1226篇
耳鼻咽喉   2276篇
儿科学   3033篇
妇产科学   3770篇
基础医学   24274篇
口腔科学   3414篇
临床医学   15361篇
内科学   31174篇
皮肤病学   4448篇
神经病学   12118篇
特种医学   8133篇
外科学   22093篇
综合类   2179篇
现状与发展   5篇
一般理论   81篇
预防医学   9833篇
眼科学   4325篇
药学   13744篇
中国医学   1614篇
肿瘤学   12777篇
  2023年   992篇
  2022年   2760篇
  2021年   4855篇
  2020年   2476篇
  2019年   3601篇
  2018年   4447篇
  2017年   3274篇
  2016年   4227篇
  2015年   5695篇
  2014年   6985篇
  2013年   8446篇
  2012年   12798篇
  2011年   12417篇
  2010年   7332篇
  2009年   6127篇
  2008年   9366篇
  2007年   9216篇
  2006年   8494篇
  2005年   8077篇
  2004年   7193篇
  2003年   6228篇
  2002年   5429篇
  2001年   4402篇
  2000年   4063篇
  1999年   3281篇
  1998年   1315篇
  1997年   1000篇
  1996年   952篇
  1995年   865篇
  1994年   755篇
  1993年   650篇
  1992年   1576篇
  1991年   1575篇
  1990年   1360篇
  1989年   1245篇
  1988年   1167篇
  1987年   1041篇
  1986年   1020篇
  1985年   894篇
  1984年   654篇
  1983年   571篇
  1982年   401篇
  1981年   381篇
  1980年   340篇
  1979年   527篇
  1978年   410篇
  1977年   392篇
  1976年   347篇
  1974年   359篇
  1973年   333篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
The effect of acute and subchronic dosing with etodolac on the renal PGE2 and 6-keto-PGF concentrations in the normal rat were studied. Etodolac and other nonsteroidal antiinflammatory drugs (NSAIDs) were administered orally, at equieffective antiinflammatory doses, to normal rats either as a single dose or as seven daily doses. Whole kidney prostaglandin (PG) concentrations were measured. In the acute study, etodolac (3 mg/kg) did not significantly lower the PGE2 levels for up to 4 hr postdosing. In contrast, naproxen (3 mg/kg) and piroxicam (0.5 mg/kg) significantly decreased the PGE2 levels to about 20% and 60% of control, respectively. Similar reductions in 6-keto-PGF concentrations were observed. In the subchronic study, etodolac (3 mg/kg/day) did not lower either PGF2 or 6-keto-PGF concentrations whereas naproxen (3 mg/kg/day), piroxicam (0.5 mg/kg/day), indomethacin (1 mg/kg/day), and aspirin (300 mg/kg/day) significantlydecreased both PGs. In both studies, the effect of etodolac was significantly different from that of the NSAIDs. It is concluded that etodolac possesses only a very weak capacity to lower renal PGs, and therefore is unlikely to cause any renal complications related to PG biosynthesis inhibition.  相似文献   
95.
96.
To assess the magnitude and nature of interpersonal violence resulting in hospitalisation of children and to identify subgroups at risk of repeat hospital admissions, a population-based, retrospective study of all violence hospitalisations in Western Australia for children aged 9 years or less was undertaken, using the 1990–2004 linked data retrieved from the Western Australian Mortality Database and the Hospital Morbidity Data System.
Of the 747 patients aged <10 years incurring 834 hospitalisations for the consequences of violence during the study period, 570 (76%) were less than 4 years of age. A total of 43 deaths from violence were recorded and 74 (9%) patients were admitted for more than one episode of violence. Victims aged 0–4 years from rural (hazard ratio [HR] = 2.72; 95% confidence interval [CI] 1.35, 5.43) and remote parts (HR = 2.79; 95% CI 1.25, 6.25) of the state were at increased risk of a subsequent admission for violence compared with those residing within the metropolitan area. Indigenous children aged 5–9 years were significantly more likely (HR = 3.57; 95% CI 1.14, 11.13) to incur a second hospitalisation for violence than their non-Indigenous counterparts. The identification of young victim subgroups at high risk of repeat hospitalisations is important for developing intervention strategies to reduce the burden of interpersonal violence. Young children aged 0–4 years living in rural and remote locations and Indigenous children aged 5–9 years should be specifically targeted for attention.  相似文献   
97.
Introduction Suprasellar arachnoid cysts are uncommon developmental anomalies that are most often diagnosed in childhood. Because the natural history and pathogenesis of these remain poorly defined, optimal treatment guidelines are not yet established.Case report We report a case of spontaneous disappearance of a suprasellar arachnoid cyst that persisted after a ventriculoperitoneal shunt performed 10 years earlier. A 5-year-old boy presented with impaired visual acuity and urinary incontinence. Magnetic resonance (MR) imaging showed a large suprasellar cyst with noncommunicating hydrocephalus. A ventriculoperitoneal shunt was put in place to alleviate current aggravation of hydrocephalus symptoms. Because of the persistent size of the cyst and signs of brainstem compression on a repeat computed tomography (CT), we recommended surgical exploration and decompression. However, the boy’s parents declined any further surgical treatment, and the patient was subsequently lost to follow-up for 10 years. When the patient returned to our clinic at the age of 15 years, a repeat MR scan showed a complete disappearance of the cyst. His family denied any significant interval history.Discussion This case represents only the third reported case of spontaneous disappearance of a suprasellar arachnoid cyst. We discuss possible mechanisms and clinical characteristics of the disappearance of the arachnoid cyst with review of the literature.  相似文献   
98.
Lymphomatoid granulomatosis (LG) is a potentially malignant lymphoproliferative disorder. The lung is the most common involved site, followed by the skin and nervous system. However, LG of the central nervous system presenting with Parkinsonism is very rare. We report a patient with LG who presented with parkinsonian features such as bilateral rigidity, bradykinesia, and agitation. Brain magnetic resonance imaging showed multifocal punctuate enhanced lesions in both supra- and infratentorial areas. Steroid pulse therapy resulted in a dramatical improvement in the symptoms and MRI abnormalities.  相似文献   
99.
OBJECTIVE: The aim of this study was to evaluate the usefulness of measurement of the angle between bilateral renal pelves on axial views in the prenatal ultrasonographic diagnosis of horseshoe kidney. METHODS: We retrospectively measured the renal pelvic angle in 19 fetuses with horseshoe and 20 fetuses with normal kidneys in the second and third trimesters. Renal pelvic angle was defined as the angle between the long axis of the renal pelves on the axial view of the abdomen. We compared the renal pelvic angles of horseshoe and normal kidneys with unpaired t-test. Taking 140 degrees as a cut-off value, we calculated the sensitivity, specificity and accuracy of pelvic angle measurement for the prenatal diagnosis of horseshoe kidney. RESULTS: The mean pelvic angles in the fetuses with horseshoe kidney were 116 degrees and 110 degrees in the second and third trimester, respectively. In the normal fetuses, the equivalent angles were 172 degrees and 161 degrees. The difference between the two groups was statistically significant (P < 0.01). Using 140 degrees as the discriminating criterion, the sensitivity, specificity and accuracy of renal pelvic angle measurement for the prenatal diagnosis of horseshoe kidney were all 100%. Fifteen of 19 fetuses with horseshoe kidney had no other abnormality. Four (21%) fetuses had severe complex abnormalities which were associated with trisomy 18 in three cases. CONCLUSION: Observation and measurement of the renal pelvic angle is a simple and useful method in the prenatal diagnosis of the horseshoe kidney.  相似文献   
100.
Serum IgA and IgG functional antibodies and their subclasses to Streptococcus pneumoniae capsular antigen found in two aged‐matched cohorts of children with and without otitis media with effusion The relationship between acute otitis media and otitis media with effusion (OME) is uncertain and the aetiology of OME is multifactorial. Otitis media with effusion may be an inflammatory condition; both bacteria and viral infections could play a part in this inflammation. The four bacteria Streptococcus pneumoniae, Haemophilus influenza, Staphylococcus aureus and Branhamella catarrhalis cause 60% of the infections whereas S. pneumoniae accounts for up to 35%. IgA provides the dominant surface response to polysaccharide and lipopolysaccharide antigens, of which IgA2 is the main subclass. Once the mucosa has been breached, most protection is provided by IgG. IgG2 acts mainly against bacterial capsular antigens. This study looked at two groups of 50 children with and without OME who were aged between 3 and 10 years. The aims were to determine if, firstly, the levels of the serum immunoglobulins were different in the two groups, secondly whether these children made the appropriate antibody response to the capsular antigen to S. pneumoniae (PCP), and finally if there was a delay in the maturity of the IgA response. The total IgG, IgA and all subclass levels were measured using radial immunodiffusion. Levels of functional IgA and IgG were measured using ELISAs (25 patients in each group). The results were analysed with non‐parametric tests. The immunoglobulin levels were within the normal levels for both groups. There were very good correlations between the IgG total anti‐PCP and the IgG2 anti‐PCP (R > 0.9, p = 0.001). There was a good correlation between the levels of both IgG total and IgG2 anti‐PCP against IgA total anti‐PCP in both groups (R > 0.85, p > 0.01). This confirms a normal antibody response between both groups of patients. The ages of the controls and patients (50 samples) were correlated with increasing titres of circulating functional antibodies (P = 0.001). This is highly suggestive of a normal age‐related response. In conclusion, the findings were contradictory to our original hypothesis that there is a subtle difference in surface protection between children with and without OME. We believe that a previous history of recurrent acute otitis media is unrelated to the development of OME after 3 years of age.  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