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   3671篇
  免费   218篇
  国内免费   5篇
耳鼻咽喉   38篇
儿科学   132篇
妇产科学   121篇
基础医学   425篇
口腔科学   66篇
临床医学   195篇
内科学   830篇
皮肤病学   85篇
神经病学   358篇
特种医学   236篇
外科学   576篇
综合类   99篇
一般理论   1篇
预防医学   139篇
眼科学   149篇
药学   252篇
中国医学   8篇
肿瘤学   184篇
  2023年   28篇
  2022年   56篇
  2021年   103篇
  2020年   48篇
  2019年   90篇
  2018年   130篇
  2017年   76篇
  2016年   106篇
  2015年   118篇
  2014年   149篇
  2013年   151篇
  2012年   288篇
  2011年   279篇
  2010年   146篇
  2009年   117篇
  2008年   189篇
  2007年   195篇
  2006年   184篇
  2005年   149篇
  2004年   161篇
  2003年   134篇
  2002年   110篇
  2001年   110篇
  2000年   85篇
  1999年   61篇
  1998年   31篇
  1997年   18篇
  1996年   15篇
  1995年   11篇
  1993年   12篇
  1992年   43篇
  1991年   34篇
  1990年   38篇
  1989年   33篇
  1988年   27篇
  1987年   31篇
  1986年   34篇
  1985年   25篇
  1984年   29篇
  1983年   20篇
  1982年   19篇
  1979年   14篇
  1978年   16篇
  1977年   15篇
  1975年   13篇
  1974年   13篇
  1973年   14篇
  1970年   12篇
  1968年   13篇
  1967年   13篇
排序方式: 共有3894条查询结果,搜索用时 31 毫秒
71.
Most patients with coronavirus disease 2019 (COVID-19) have mild to moderate illness not requiring hospitalization. However, no study has detailed the evolution of symptoms in the first month of illness.At our institution, we conducted remote (telephone and video) visits for all adult outpatients diagnosed with COVID-19 within 24 h of a positive nasopharyngeal polymerase chain test for SARS-CoV-2. We repeated regular video visits at 7, 14, and 28 days after the positive test, retrospectively reviewed the prospective data collected in the remote visits, and constructed a week by week profile of clinical illness, through week 4 of illness.We reviewed the courses of 458 symptomatic patients diagnosed between March 12, 2020, and June 22, 2020, and characterized their weekly courses. Common initial symptoms included fever, headache, cough, and chest pain, which frequently persisted through week 3 or longer. Upper respiratory or gastrointestinal symptoms were much shorter lived, present primarily in week 1. Anosmia/ageusia peaked in weeks 2 to 3. Emergency department visits were frequent, with 128 visits in the 423 patients who were not hospitalized and 48 visits among the 35 outpatients (7.6%) who were eventually hospitalized (2 subsequently died). By the fourth week, 28.9% said their illness had completely resolved. After the 4-week follow up, 20 (4.7%) of the 423 nonhospitalized patients had further medical evaluation and management for subacute or chronic COVID-19 symptoms.Mild to moderate outpatient COVID-19 is a prolonged illness, with evolving symptoms commonly lasting into the fourth week of illness.  相似文献   
72.
Thirty-one patients with chronic severe anemia of more than 3 months' duration (hemoglobin less than 7 gm/dl) and no underlying heart disease were studied by means of M-mode, two-dimensional, and Doppler echocardiography; an equal number of normal control subjects was also studied. There are conflicting reports regarding the influence of chronic severe anemia on systolic myocardial function, but diastolic function has not been systematically assessed. It is also uncertain whether anemia alone can cause heart failure in a structurally normal heart. We therefore performed a detailed study of echocardiographic indexes of systolic and diastolic left ventricular function in these patients. We found that patients with anemia have significantly faster heart rates and lower diastolic and mean blood pressures than normal subjects. They also have a significantly elevated cardiac output and stroke volume and larger left ventricles. Left ventricular contractility, assessed by the end-systolic stress-dimension relationship, was enhanced. There was no systematic evidence of diastolic dysfunction by Doppler assessment of mitral inflow. There was also no clinical evidence of congestive heart failure. We conclude that chronic severe anemia leads to a hyperdynamic state with systolic hyperfunction and no impairment of diastolic function. Anemia does not lead to congestive heart failure in the absence of underlying heart disease.  相似文献   
73.

Background

Neck pain is a common musculoskeletal complaint in computer users due to prolonged static or awkward work postures. It has been shown that pathogenesis of neck pain is associated with scapular movement impairment syndromes. However, there is a dearth of literature in treatment based on these syndromes.

Aim

To identify the effects of movement impairment-based treatment in the management of mechanical neck pain, in computer users.

Methods

In the present study, twenty-seven subjects were recruited. Based on the identified scapular impairment syndrome, they were trained with scapular movement impairment-based exercises for four weeks. Pain, disability and cervical range of motion were measured with numeric pain rating scale, neck disability index and inclinometer, respectively, at baseline and at four weeks.

Results

Twenty-one subjects completed the study. After four weeks, a significant difference of 4.81 points for numeric pain rating scale and 24.47% for neck disability index at 95% CI were found. The cervical range of motion showed a significant change (p < 0.05) of 10.09° for flexion, 24.47° for extension, 7.42° for right lateral flexion, 6.23° for left lateral flexion, 15.52° for right rotation and 14.95° for left rotation at 95% CI.

Conclusions

Exercises based on scapular impairment syndromes were given for four weeks. It was found to be effective in relieving pain and reducing dysfunction in computer users with mechanical neck pain  相似文献   
74.
75.

Background

Emergency departments rely on CT scans to manage trauma victims, especially for head injuries. Although the detection of an undisplaced fracture on a CT scan of the head without significant intracranial findings may be insignificant for a clinician, such cases are of paramount importance for medico-legal purposes because they help ascertain the nature, manner, and cause of the head injury.

Aims

The study was conducted with the objective of knowing the sensitivity and specificity of ante-mortem CT scan findings indicating the presence or absence of skull fractures.

Methods

Findings were confirmed during post-mortem examination of the subjects who had died during management but who had not had any surgical intervention. A comparative study of ante-mortem CT scan and autopsy findings with respect to fracture in traumatic head injuries was undertaken on 60 deceased individuals brought in for medico-legal post-mortem examination over a period of two years.

Results

Considering the autopsy findings as the gold standard, we have concluded that 14.6 per cent of the fractures were missed on CT scan findings compared to fractures found during autopsy. The sensitivity of CT scan for skull fractures was found to be 85.4 per cent and specificity was 100 per cent. Kappa was 0.787, which shows good agreement with p<0.001, which was highly significant.

Conclusion

In developing countries, images are interpreted in the axial plane only on a CT scan of the head, which may be due to a lack of financial and human resources. For better delineation of fractures, the use of techniques like multi-detector CT with sagittal and coronal reformations should be considered in the routine interpretation of a CT scan of the head.  相似文献   
76.
Glanzmann thrombasthenia (GT) is an autosomal recessive platelet function disorder characterized by mucocutaneous bleeding as the most common clinical phenotype. Patients with GT have normal platelet counts, platelet morphology but reduced platelet aggregation in response to various agonists. Homozygosity or compound heterozygosity for variants in the ITGA2B/ITGB3 genes is the genetic basis for GT. Establishing a molecular diagnosis is definitive and is important for predictive testing. Using multi-gene panels is an accurate, faster, and cost-effective mode as compared to Sanger sequencing in large genes. We used a targeted resequencing based approach to identify pathogenic variants in eight cases in seven families. These variants were validated using Sanger sequencing in patients as well as family members and were predicted probably pathogenic using in-silico prediction tools. The variants include three missense (3/7 = 43%) (ITGA2B:c.1028 T > C, ITGA2B:c.1186G > A, ITGB3:c.1388G > C), two deletions (ITGA2B:c.559delG, ITGA2B:c.3092delT), one duplication (ITGA2B:c.1424_1427dupAGGT) and nonsense variant (ITGA2B:c.2578C > T, p.Gln860Ter). Except for one case which was compound heterozygous, the rest of the cases were homozygous. We found two novel variants that are reported for the first time in GT. The targeted resequencing based approach revealed varied genetic variants in North Indian patients, including two novels ones. The high yield of our panel indicates its suitability for usage in larger cohorts for the genetic diagnosis of GT patients. This approach is cost-effective and less cumbersome as compared to Sanger sequencing for these large size genes with multiple exons. The information so obtained is helpful in prenatal testing, carrier analysis, and genetic counseling.  相似文献   
77.
The alterations in serum levels of T3, T4, TSH and TBG, TSH response to 100 mug iv TRH, and urinary excretion of T3 and T4 were studied in 8 healthy men at sea level (SL), on days 1, 2, 4, 8 and 16 after arrival by air at high altitude (3,700 m, HA), and during days 5 to 7 after their return to SL. No significant alterations in serum levels of TSH and TBG or TSH response to TRH were observed during exposure to HA or on return to SL. There was, however, an acute elevation in both serum total T3 and T4. Serum total T3 from a mean basal+/-SE value of 128+/-13 ng/dl increased to 320+/-18 on day 1 and remained significantly elevated at 225+/-48 up to day 8 after arrival at high altitude. Similarly serum total T4 increased from basal level of 9+/-0.92 mug/dl to 15.2+/-1.2 and remained elevated till day 16 and it was 11+/-1.19 mug/dl during days 5 to 7 after return to SL. The urinary excretion of both T3 and T4 was decreased. These changes perhaps were the result of complex physiologic adjustments on acute exposure to high altitude, like shrinkage of the T3 and T4 distribution pools, altered binding capacities of thyroid hormones binding proteins, and a reduction in clearance of thyroid hormones from the plasma compartment; and were probably not suggestive of an enhanced thyroid activity. Their actual significance in high altitude adaptation in man is not clearly understood.  相似文献   
78.
GOALS: To report the use of pH-impedance testing in evaluating patients with suspected gastroesophageal reflux disease (GERD) with atypical symptoms. BACKGROUND: Although the role of acid reflux in causing atypical GERD symptoms is generally accepted, the role, if any, of nonacid reflux is controversial, largely because until recently it has not been possible to detect nonacid reflux. The advent of intraluminal combined pH impedance testing (MII-pH), to detect nonacid reflux has heightened interest in its possible contribution to atypical symptoms. STUDY: Fifty consecutive patients referred for MII-pH testing to evaluate the cause of atypical symptoms presumed due to GERD were evaluated. The symptoms were either refractory to acid inhibition therapy or so atypical that further work up was desired by the referring physician. Patients underwent MII-pH testing to determine whether reflux was present, and, if so, if it was due to acid, nonacid, or gas. RESULTS: Only 16%, 22%, and 2% patients were found to have symptoms due to acid reflux, nonacid reflux, or both, respectively. Ten percent of these patients had gas reflux. MII-pH testing was useful in redirecting the management of patients who did not have reflux as the cause of their symptoms. CONCLUSIONS: MII-pH testing is useful in determining whether gastroesophageal reflux is present in patients with atypical symptoms that have not responded to proton pump inhibitor therapy. It also distinguishes between reflux due to acid, nonacid, and gas, with consequences for management.  相似文献   
79.
Over the last two decades, there has come about a recognition that chaotic dynamics is pervasive in the solar system. We now understand that the orbits of small members of the solar system-asteroids, comets, and interplanetary dust-are chaotic and undergo large changes on geological time scales. Are the major planets' orbits also chaotic? The answer is not straightforward, and the subtleties have prompted new questions.  相似文献   
80.
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