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   3053篇
  免费   152篇
  国内免费   39篇
耳鼻咽喉   69篇
儿科学   118篇
妇产科学   72篇
基础医学   453篇
口腔科学   42篇
临床医学   239篇
内科学   750篇
皮肤病学   77篇
神经病学   230篇
特种医学   88篇
外科学   479篇
综合类   15篇
预防医学   135篇
眼科学   48篇
药学   155篇
中国医学   1篇
肿瘤学   273篇
  2023年   33篇
  2022年   44篇
  2021年   92篇
  2020年   50篇
  2019年   61篇
  2018年   92篇
  2017年   64篇
  2016年   72篇
  2015年   88篇
  2014年   108篇
  2013年   145篇
  2012年   212篇
  2011年   234篇
  2010年   137篇
  2009年   102篇
  2008年   185篇
  2007年   178篇
  2006年   185篇
  2005年   202篇
  2004年   186篇
  2003年   160篇
  2002年   141篇
  2001年   38篇
  2000年   38篇
  1999年   26篇
  1998年   31篇
  1997年   25篇
  1996年   27篇
  1995年   17篇
  1994年   13篇
  1993年   12篇
  1992年   26篇
  1991年   18篇
  1990年   21篇
  1989年   31篇
  1988年   18篇
  1987年   15篇
  1986年   15篇
  1985年   19篇
  1984年   5篇
  1983年   12篇
  1980年   6篇
  1979年   10篇
  1977年   3篇
  1976年   10篇
  1975年   3篇
  1974年   3篇
  1973年   3篇
  1971年   3篇
  1968年   4篇
排序方式: 共有3244条查询结果,搜索用时 78 毫秒
1.
2.
3.
The purpose of this study was to assess 7 methods of fixation for a midtarsal osteotomy. Polyurethane foam models (N = 6) and cadaver specimens (N = 4-7) were used to examine the force generated by the different constructs of fixation. A midtarsal osteotomy was performed on each specimen in the test groups. The osteotomies were fixated either with 2 parallel 0.062-in Kirschner wires and 40-mm-long, 4-mm partially threaded, cancellous, cannulated titanium screws, an external ring fixator (frame), a frame with wires tensioned (tension), a frame with wires tensioned and compressed toward the osteotomy (tension and compression), a frame with tension, compression, and parallel Kirschner wires, or a frame with tension, compression, and two 4.0 cannulated parallel screws, respectively. Each model was fixated, and the force generated by the construct across the osteotomy was recorded via the use of pressure-sensitive film. Statistical analysis of the data in the polyurethane foam group determined that the use of frame with tension, compression, and two 4.0 parallel cannulated screws was statistically superior to 1) frame, 2) frame with tension, 3) 2 parallel Kirschner wires, 4) two 4.0 cannulated parallel screws, and 5) frame with tension and compression. A cadaver study determined that the frame with tension, compression, and 2 parallel Kirschner wires was statistically superior to 1) frame and 2) two parallel Kirschner wires. These findings suggest that there is a difference in the force generated by the type of fixation construct across a midtarsal osteotomy.  相似文献   
4.
BACKGROUND: The HOXA1 gene plays a major role in brainstem and cranial morphogenesis. The G allele of the HOXA1 A218G polymorphism has been previously found associated with autism. METHODS: We performed case-control and family-based association analyses, contrasting 127 autistic patients with 174 ethnically matched controls, and assessing for allelic transmission disequilibrium in 189 complete trios. RESULTS: A, and not G, alleles were associated with autism using both case-control (chi(2) = 8.96 and 5.71, 1 df, p <.005 and <.025 for genotypes and alleles, respectively), and family-based (transmission/disequilibrium test chi(2) = 8.80, 1 df, p <.005) association analyses. The head circumference of 31 patients carrying one or two copies of the G allele displayed significantly larger median values (95.0th vs. 82.5th percentile, p <.05) and dramatically reduced interindividual variability (p <.0001), compared with 166 patients carrying the A/A genotype. CONCLUSIONS: The HOXA1 A218G polymorphism explains approximately 5% of the variance in the head circumference of autistic patients and represents to our knowledge the first known gene variant providing sizable contributions to cranial morphology. The disease specificity of this finding is currently being investigated. Nonreplications in genetic linkage/association studies could partly stem from the dyshomogeneous distribution of an endophenotype morphologically defined by cranial circumference.  相似文献   
5.
Forty consecutive adult patients under the age of 50 with acute non-lymphoblastic leukemia (ANLL) in first complete remission, underwent autologous bone marrow transplantation (ABMT) between March 1984 and April 1990. The conditioning regimen employed included cyclophosphamide and total body irradiation, followed by the administration of unpurged ABMT. The median time from diagnosis to transplant was 7 months (3-15 months), and the median time from complete remission to ABMT was 4 months (range 3-9 months). Twenty-two (51%) patients remain in complete remission 6-81 months (median 24 months) after ABMT.

The causes of death were, recurrent leukemia (11 patients), parenchymal toxicities such as acute respiratory distress syndrome and veno-occlusive disease (3 patients), hemorrhage (2 patients) and infection (2 patients). Eleven patients relapsed after 3-12 months (median 5 months). This study has produced survival data comparable to those of other institutions employing TBI for either allo or autotransplants.  相似文献   
6.
A simple and efficient method is described for the direct determination of Isoniazide (INH) and Pyrazinamide (PZAm) in human plasma, based on reversed-phase HPLC. A number of other antitubercular drugs such as p-Aminosalycylic acid (PAS), Streptomycin (STM) and Ethambutol (ETH) and the major metabolites of the two investigated drugs, namely N-Monoacetylisoniazide (AcINH) and Pyrazinoic acid (PZAc), were shown not to interfere with the assay method. A potential application of the method to routine clinical monitoring of antitubercular drugs is discussed.  相似文献   
7.
The prevalence of primary headache (PH) in a multiple sclerosis (MS) sample vs. control healthy subjects was investigated at a neurological clinic in 2004–2005: 122 of 238 (51%) MS patients and 57 of 238 (23%) controls proved to be affected by headache. The groups did not differ for the rates of PH types. Headache types of MS patients were comparable to those of PH patients that were observed at the same institute in a case-control comparison. First symptoms of headache preceded those of MS in two thirds of cases. Headache features did not significantly change after MS onset. Comorbidity of MS and PH could be explained by some common clinical and biological traits.  相似文献   
8.
BACKGROUND: Color Doppler ultrasonography of intrarenal arterial resistance index (RI), performed early after kidney transplant, has proven to reliably predict short-term allograft function. The aim of this study was to assess whether it could also predict long-term renal function. METHODS: We retrospectively analysed 76 kidney transplant patients who underwent RI assessment within 1 month after the transplant, subdivided into two groups according to RI values, lower (group A) or higher (group B) than its median value (0.635). RESULTS: Compared with group A subjects, the patients of group B were older at the time of transplant (42 +/- 9 vs 35 +/- 8 years; P = 0.001), the donor age was also older (41 +/- 16 vs 33 +/- 13 years; P = 0.02) and had a slightly higher proteinuria (0.54 +/- 0.5 vs 0.32 +/- 0.2 g/24 h; P = 0.02). Serum creatinine, ciclosporin or tacrolimus trough level, arterial blood pressure, number of human leukocyte antigen (HLA) mismatches, anti-hypertensive medications and incidence of delayed graft function were not significantly different between the two groups. By univariate analysis, RI turned out to directly correlate with the recipient age, donor age and daily proteinuria (P = 0.007, P = 0.0007 and P = 0.02, respectively). Multivariate analysis showed that only donor and recipient age maintained their independent predictive value on RI. Kaplan-Meier analysis, considering a serum creatinine increase >50% as the endpoint of the study, showed a statistically significant different graft survival in the two groups (log-rank test = 5.489; P = 0.01). The univariate relative risk of deterioration of graft function among patients with higher RI was 3.77. Proteinuria and recipient age increased the risk as well. CONCLUSIONS: Our data seem to suggest that early determination of RI can help predict long-term graft function in kidney transplant recipients.  相似文献   
9.
OBJECTIVE: Epilepsy with mutation of the CDKL5 gene causes early seizures and is a variant of Rett syndrome (MIM (312750), which is reported typically as infantile spasms. The purpose of this study was to analyze the epileptic histories and EEGs of patients with the CDKL5 mutation. METHODS: We reviewed the epilepsy histories and electroclinical analyses of three girls aged 9.5, 7.4, and 9.4 years, each with a mutation of the CDKL5 gene. RESULTS: We revealed the presence of an encephalopathy that started by 1.5 months of age. At first, seizures involved tonic spasms or complex partial seizures, and were complicated by the later appearance of complex partial, tonic, and unexpectedly, myoclonic seizures. This form of epilepsy was drug resistant. Routine and prolonged video EEGs both displayed a homogeneous electroclinical pattern consisting of (a) unique background with diffuse high voltage sharp waves of 6-7 Hz, and absence of the typical rhythmic frontal-central theta activity present in Rett syndrome; (b) unique awake and sleep background, with diffuse, high voltage, continuous sharp waves with multifocal and diffuse spikes; (c) rhythmic, diffuse, 15 Hz activity accompanied clinically by tonic seizures; (d) intercritical pattern with pseudoperiodic, diffuse, sharp waves or pseudoperiodic, diffuse spike and polyspike or wave discharges; and (e) diffuse, spike, polyspike and wave discharges accompanied by massive or focal myoclonias or both. CONCLUSIONS: Patients with the CDKL5 mutation have an early onset, epileptic encephalopathy in infancy that evolves into myoclonic seizures in childhood with a unique EEG pattern. SIGNIFICANCE: Recognizing this type of encephalopathy could be useful in prompting clinicians to proceed further with their diagnostic work in patients not fitting the criteria of classical Rett syndrome.  相似文献   
10.
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