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   2348篇
  免费   210篇
  国内免费   6篇
耳鼻咽喉   18篇
儿科学   128篇
妇产科学   34篇
基础医学   274篇
口腔科学   45篇
临床医学   245篇
内科学   601篇
皮肤病学   63篇
神经病学   189篇
特种医学   140篇
外国民族医学   4篇
外科学   285篇
综合类   33篇
预防医学   114篇
眼科学   9篇
药学   191篇
中国医学   2篇
肿瘤学   189篇
  2022年   21篇
  2021年   41篇
  2020年   19篇
  2019年   28篇
  2018年   47篇
  2017年   19篇
  2016年   29篇
  2015年   53篇
  2014年   66篇
  2013年   101篇
  2012年   118篇
  2011年   125篇
  2010年   77篇
  2009年   84篇
  2008年   116篇
  2007年   102篇
  2006年   120篇
  2005年   111篇
  2004年   120篇
  2003年   115篇
  2002年   82篇
  2001年   62篇
  2000年   50篇
  1999年   61篇
  1998年   48篇
  1997年   48篇
  1996年   50篇
  1995年   44篇
  1994年   28篇
  1993年   25篇
  1992年   46篇
  1991年   34篇
  1990年   43篇
  1989年   43篇
  1988年   42篇
  1987年   43篇
  1986年   39篇
  1985年   26篇
  1984年   28篇
  1983年   16篇
  1982年   15篇
  1981年   16篇
  1979年   11篇
  1977年   14篇
  1974年   11篇
  1971年   11篇
  1970年   21篇
  1969年   16篇
  1968年   11篇
  1967年   10篇
排序方式: 共有2564条查询结果,搜索用时 15 毫秒
51.
To determine the utility of adrenocortical scintigraphy with I131-6 beta-iodomethyl-19-nor-cholesterol (NP59) in incidentally discovered adrenal masses, we studied 12 patients with a unilateral adrenal mass and without other primary tumors or signs of pheochromocytoma or hyperfunctioning adenoma. Ten patients had an adenoma (size: 12 to 35 mm), the diagnosis was made by surgery or by no change in size on repeated CT scans. The NP59 scintigraphy showed an increased uptake on the side of the tumor in 8 cases with a decreased uptake of contra-lateral gland in 7 cases. Hormonal investigations of glucocorticoid function suggested supranormal or fluctuant cortisol secretion in 5 cases as assessed by moderately elevated urinary free cortisol or by incomplete dexamethasone suppression test. These abnormalities disappeared after surgery. Two patients had normal bilateral uptake of NP59, the sizes of the tumors were 12 and 20 mm. Two patients had an extra-adrenal tumor. The NP59 scintigraphy showed a moderately decreased uptake on the side of the hematoma of one patient and a compression of the normal adrenal by ganglioneuroma of the other patient. Our results and those of other authors suggest that positive NP59 scintigraphy could confirm the cortical nature of an incidentally discovered adrenal mass, probably an adenoma that must be followed up morphologically and functionally. No uptake by a tumor greater than 2 cm suggests a primary malignancy or extra-adrenal origin which must be diagnosed by invasive methods.  相似文献   
52.
53.
STUDY OBJECTIVE: Our aim was to document the following in patients with septic shock and disseminated intravascular coagulation (DIC): (1) the influence of DIC in the mortality rate and the occurrence of organ failure; (2) the comparative prognostic value of initial antithrombin III (ATIII), protein C (PC), and protein S (PS) levels; and (3) the compared pattern of sequential ATIII, PC, and PS levels according to clinical outcome. DESIGN: Demographic data, criteria of severity, mortality in ICU, frequency of organ failure, hemodynamic and oxygenation parameters, and laboratory findings were compared in patients with septic shock according to the occurrence of DIC. Initial and sequential levels of ATIII (activity), PC (antigen and activity), PS (total and free), and C4b binding protein (C4bBP) were compared according to the outcome in patients with DIC. PATIENTS: Sixty patients with septic shock were studied. Forty-four entered the group DIC+; 16 entered the group DIC-. RESULTS: Simplified acute physiologic score (SAPS), frequency of acquired organ failure, blood lactate, and transaminase values were significantly higher in the group DIC+. The mortality rate reached 77 percent in group DIC+ vs 32 percent in DIC- (p less than 0.001). In patients with DIC, a fatal outcome was associated with higher bilirubin and transaminase levels, lower PaO2/FIo2 ratio, Vo2, Do2 and O2 extraction. In the group DIC+, all patients but two had severe deficiencies in ATIII and PC levels. Significant correlations were found between initial ATIII and PC levels, PC and free PS levels, and free PS and C4bBP levels. Initial ATIII levels had the best prognostic value for prediction of subsequent death. Serial measurements were consistent with a prolonged ATIII and PC deficiency with significantly different levels between survivors and nonsurvivors. CONCLUSIONS: DIC is a strong predictor of death and multiple organ failure in patients with septic shock. Sequential ATIII, PC, and PS measurements were consistent with prolonged consumption or inhibition that might account for a sustained procoagulant state and inhibition of fibrinolysis. The initial ATIII level was the best laboratory predictor of death in these patients.  相似文献   
54.
55.
Currently, the role of dopaminergic and somatostatinergic agonists in the treatment of pituitary adenomas is quite well established. Nevertheless, a clearer understanding of the expression of dopaminergic and somatostatinergic receptors at the cellular level of pituitary adenomas as well as the development of newer analogues compounds may drastically change current therapeutic modalities. In particular, the emphasis on the co-expression of different receptors types or subtypes in adenomatous cells highlights functional interactions between receptors leading to an increase in their activity. Newer molecules are also in the process of development : new somatostatin analogues with more universal binding properties to different receptors subtypes, as well as chimeric molecules capable of binding to somatostatinergic and dopaminergic receptors. In the midst of GH-secreting pituitary adenomas, a positive correlation exists between the expression of Sst2 mRNA and the inhibition of GH release by somatostatin analogues. The involvement of Sst5 subtype in adenomas resistant to preferential Sst2 agonists has recently been proved. Another recently developed compound has a more universal Sst binding profile. This compound, named SOM-230, has a 25, 5 and 40 times higher binding affinity to Sst1, Sst3 and Sst5 receptors respectively, and 2,5 times lower affinity to Sst2, when compared to octreotide. SOM-230 could therefore allow for much more effective methods in treating patients suffering from acromegaly. Besides, the use of a chimeric molecule presenting a binding affinity to both Sst2 and D2 subtypes (BIM-23A287) inhibits the secretion of GH in ways similar to the Sst2 or D2 agonists used alone or concurrently but however in a concentration 50 times lower than that of the latter. The discovery of Sst5 and D2 subtypes at the level of corticotropic adenomas reveals newer therapeutic perspectives with promising preliminary results with the use of SOM-230 ; these finding lead to a rise in interest in cabergoline. In the midst of non-functioning pituitary adenomas, the expression of Sst2, Sst3 and D2 receptors will perhaps allow the use of combined therapies associating the new somatostatin analogues to the dopaminergic agonists or even use dopastatin (BIM-23A760, chimeric molecule Sst2-Sst5-D2). The preliminary results obtained in vitro with this molecule are actually encouraging since they show a dose dependent inhibition of the cellular replication mechanisms in 60 % of the cases. Finally, concerning prolactinomas the discovery of Sst5 receptors lead to consider the use of somatostatinergic agonists specific to the Sst5 receptor, SOM-230 in particular. Nevertheless, it seems that adenomas resistant to dopaminergic agonist due to a lack of expression of D2 receptor fail to express Sst5 receptors as well. On the other hand, dopastatin appears to be more efficient than cabergoline in the management of this type of adenomas. Therefore, the growing awareness concerning the mechanisms involved in the control of pituitary secretions as well as cellular proliferation will perhaps allow physicians to treat the pathology of pituitary adenomas, macroadenomas in particular, using solely pharmacological means instead of invasive surgical procedures and/or radiotherapy.  相似文献   
56.
The aim of this study performed in Normandy, France, was to analyze the pharyngeal meningococcal carriage at the peak of a clonal meningococcal B outbreak, which was subsequently controlled using an outer membrane vesicle vaccination. This cross-sectional study included randomly selected subjects aged 1–25 years. Carriers and non carriers were compared using unconditional logistic regression. Among the 3,522 volunteers, there were 196 (standardized rate: 6.46 %) Neisseria meningitidis carriers, of which there were only five with the outbreak strain (B:14:P1.7,16/ST-32; standardized rate: 0.18 %). From the multivariate analysis, older age, smoking, higher degree of socialization, and social deprivation appear to favor the carriage of all the strains included. Prior antibiotic treatment up to 12 months before swabbing, even with β-lactam, was protective against carriage. Our data indicate a low overall meningococcal carriage rate with a surprising protective effect of prior antibiotic exposure. The observed low carriage rate of the epidemic strain (B:14:P1.7,16/ST-32) contrasts with the high incidence of invasive meningococcal diseases (IMD) due to this strain. Hence, our data underline the high virulence of the strain and suggest a low level of natural immunity of the population against this strain. Although highly resource-consuming, carriage studies are helpful in guiding the implementation of control measures of IMD, such as mass vaccination or chemoprophylaxis.  相似文献   
57.
BackgroundTraumatic brain injury (TBI) is a chronic pathology responsible for cognitive disorders impacting outcome. Global clinical outcome several years after TBI may be associated with anatomical sequelae. Anatomical lesions are not well described because characterizing diffuse axonal injury and brain atrophy require using specific MRI sequences with quantitative measures. The best radiologic parameter to describe the lesions long term after TBI is not known.ObjectiveWe aimed to first, assess the global volumetric and diffusion parameters related to long-term outcome after TBI and second, define the most discriminating parameter.MethodsIn this observational study, we included 96 patients with severe TBI and 22 healthy volunteers. The mean delay after TBI was 63.2 months [range 31–119]. The Glasgow Outcome Scale Extended (GOS-E) was used to assess the global long-term clinical outcome. All patients underwent multimodal MRI with measures of brain volume, ventricle volume, global fractional anisotropy (FA) and global mean diffusivity (MD).ResultsAll 96 participants had significant impairment in global FA, global MD, brain volume and ventricle volume as compared with the 22 controls (P < 0.01). Only global MD significantly differed between the “good recovery” group (GOS-E score 7-8) and the other two groups: GOS-E scores 3-4 and 5-6. Brain volume significantly differed between the GOS-E 7-8 and 3-4 groups. Global MD was the most discriminating radiological parameter for the “good recovery” group versus other patients, long term after TBI. FA appeared less relevant at this time. Global atrophy was higher in patients than controls but lacked reliability to discriminate groups of patients.ConclusionGlobal mean diffusivity seems a more promising radiomarker than global FA for discriminating good outcome long term after TBI. Further work is needed to understand the evolution of these long-term radiological parameters after TBI.  相似文献   
58.
59.
60.
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