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   7120篇
  免费   482篇
  国内免费   21篇
耳鼻咽喉   134篇
儿科学   104篇
妇产科学   121篇
基础医学   1102篇
口腔科学   151篇
临床医学   795篇
内科学   1640篇
皮肤病学   114篇
神经病学   642篇
特种医学   278篇
外国民族医学   9篇
外科学   847篇
综合类   50篇
一般理论   1篇
预防医学   447篇
眼科学   280篇
药学   395篇
  1篇
中国医学   16篇
肿瘤学   496篇
  2022年   57篇
  2021年   132篇
  2020年   90篇
  2019年   117篇
  2018年   140篇
  2017年   116篇
  2016年   103篇
  2015年   160篇
  2014年   201篇
  2013年   251篇
  2012年   371篇
  2011年   406篇
  2010年   254篇
  2009年   192篇
  2008年   362篇
  2007年   389篇
  2006年   266篇
  2005年   337篇
  2004年   299篇
  2003年   286篇
  2002年   271篇
  2001年   192篇
  2000年   205篇
  1999年   165篇
  1998年   76篇
  1997年   57篇
  1996年   60篇
  1995年   62篇
  1994年   54篇
  1992年   128篇
  1991年   125篇
  1990年   121篇
  1989年   103篇
  1988年   112篇
  1987年   94篇
  1986年   91篇
  1985年   71篇
  1984年   65篇
  1983年   72篇
  1982年   53篇
  1981年   51篇
  1980年   41篇
  1979年   71篇
  1978年   40篇
  1977年   39篇
  1976年   47篇
  1975年   35篇
  1974年   37篇
  1973年   32篇
  1972年   32篇
排序方式: 共有7623条查询结果,搜索用时 3 毫秒
91.
The postmortem determination of hyperglycaemic coma is quite difficult because of the lack of morphological findings and the difficult interpretation of biochemical parameters. Methylglyoxal (MG) is a reactive oxoaldehyde, which is mainly derived from glycolysis. An electrospray ionisation liquid chromatography–tandem mass spectrometric procedure for the determination of methylglyoxal in human serum and postmortem blood was developed. It involves protein precipitation with perchloric acid and a derivatisation step with 2,3-diaminonaphthalene. The assay was validated according to international guidelines. Serum samples from diabetics obtained at a diabetes clinic and from non-diabetics were used to assess data about reference concentrations in human serum. The assay showed linearity within the physiological concentrations in serum (5–500 ng/ml). Intraday imprecision at three concentrations was 10.3, 9.2 and 8.3 %, and interday imprecision was 15.3, 14.2 and 9.4 %; the limit of detection was 1.3 ng/ml, and limit of quantification, 3.2 ng/ml. One hundred and eighteen clinical (100 diabetics, 18 non-diabetics) and 98 forensic samples (84 non-diabetics, 14 in a status of hyperglycaemic coma) were measured. During life, diabetics showed significantly (p?<?0.001) higher serum concentrations of MG than non-diabetics. After death, concentrations of MG increased significantly (p?<?0.001). However, there was no correlation between the sum formula of Traub in vitreous humour and MG femoral blood concentrations (R?=?0.237). This indicates that MG concentrations in the deceased cannot distinguish deaths due to a hyperglycaemic coma from other causes of death.  相似文献   
92.
93.
BACKGROUND: Candida albicans is a polymorphic fungus that frequently causes systemic infection in postsurgical and trauma patients. Others have reported that Escherichia coli lipopolysaccharide (LPS) acts as a copathogen to enhance the virulence of parenteral C. albicans. Experiments were designed to clarify the effect of parenteral LPS on systemic candidiasis initiated via the oral route. MATERIALS AND METHODS: Antibiotic-treated mice were orally inoculated with C. albicans CAF2 (wild-type) or mutant HLC54 (defective in filament formation), and were given 100 microg parenteral LPS 16 h before sacrifice. Separate groups of mice were additionally exposed to intermittent hypoxia prior to LPS. At sacrifice, cecal flora and microbial translocation to the mesenteric lymph nodes were quantified. C. albicans adherence to cultured HT-29 and Caco-2 enterocytes (pretreated with LPS, or calcium-free medium to expose the enterocyte lateral surface, or both) was quantified by enzyme-linked immunoabsorbent assay. RESULTS: All mice had high numbers of cecal C. albicans, and LPS was associated with an additional increase in cecal concentrations of HLC54 but not CAF2. Translocation of HLC54, but not CAF2, appeared facilitated by hypoxia, but LPS did not facilitate translocation in any treatment group. Exposure of the lateral surface of cultured enterocytes had no effect on C. albicans adherence, although LPS consistently decreased adherence of both C. albicans strains. CONCLUSIONS: In contrast to experiments where systemic candidiasis was initiated by the parenteral route, parenteral LPS did not act as a copathogen in mice with systemic candidiasis initiated by the oral route, and these results might be related to LPS-induced alterations in C. albicans adherence to host enterocytes.  相似文献   
94.
A potentially traumatic event (PTE) contributes to trauma through its frequency, conditional probability of posttraumatic stress disorder (PTSD), and experience of other PTEs. A cross-sectional survey was conducted, enrolling 21,425 adults nationally representative of six European countries. Using the WHO-Composite International Diagnostic Interview, 8,797 were interviewed on 28 PTEs and PTSD. Prevalence of 12-month PTSD was 1.1%. When PTSD was present, the mean number of PTEs experienced was 3.2. In a multivariate analysis on PTEs and gender, six PTEs were found to be more traumatic, and to explain a large percentage of PTSD, as estimated by their attributable risk of PTSD: rape, undisclosed private event, having a child with serious illness, beaten by partner, stalked, beaten by caregiver.  相似文献   
95.
96.
Risk factors for renal scarring in children with lower urinary tract dysfunction (LUTD) were evaluated. The medical records of 120 patients were assessed concerning gender, presence of vesicoureteric reflux (VUR), bladder capacity, detrusor overactivity, residual urine, febrile urinary tract infection (UTI), bacteriuria, constipation, detrusor sphincter incoordination (DSI), high detrusor pressure at maximal cystometric capacity (PMCC), low compliance, and thickness and trabeculation of the bladder wall. Renal scarring was diagnosed by 99mtechnetium-dimercaptosuccinic acid renal scan (DMSA). Renal scarring was detected in 38 patients (31%). VUR, UTI, decreased bladder capacity, urinary residue, and trabeculated and thick bladder wall were associated with scarring at univariate analysis. Multivariate analysis showed VUR (P < 0.0001) as the independent risk factor for renal scarring. Thickness of the bladder wall was a marginal risk factor (P= 0.07). Although UTI was not a risk factor, it was associated with VUR (P= 0.03). In our analysis, VUR was the main risk factor; however, renal scarring was probably due to multifactorial causes, as VUR was associated with UTI.  相似文献   
97.
Opinion statement Atherosclerotic narrowing of the proximal internal carotid artery is an important mechanism in ischemic stroke. Optimal medical management of internal carotid stenosis includes antiplatelet agent and statin administration, blood pressure reduction, weight control, and smoking cessation. Decisions regarding the use of invasive procedures to treat carotid disease—specifically carotid endarterectomy and carotid angioplasty and stenting—must weigh the long-term risk reduction in ipsilateral ischemic stroke against the immediate intervention risks. Clinical trials evaluating the benefits of carotid endarterectomy were conducted before widespread use of statins and newer blood pressure-lowering agents such as angiotensin-receptor blockers; it is unclear what impact this may have had on trial results. Regardless, carotid endarterectomy is clearly superior to medical therapy for patients with symptomatic severe stenosis. Conversely, the benefit from endarterectomy is muted in individuals with symptomatic moderate stenosis or asymptomatic stenosis, and decisions regarding surgical intervention must incorporate surgeon proficiency and patient comorbidity. Currently, there is a lack of evidence to support the use of carotid artery angioplasty and stenting in the routine management of carotid disease. Selected patients with severe symptomatic stenosis for whom endarterectomy cannot be safely performed may still benefit from endovascular management. However, it is unlikely that asymptomatic patients or symptomatic patients with moderate stenosis considered at high risk for endarterectomy would benefit from any intervention.  相似文献   
98.
Objective. To evaluate the supraspinatus muscle radiodensity on the outlet view as an indication of a tendon tear. Design and patients. Plain radiographs and magnetic resonance imaging (MRI) examinations were obtained on both shoulders of 40 subjects aged 23–70 years, including 13 asymptomatic volunteers and 27 patients. Two readers analyzed the superior contour and the heterogeneity of the supraspinatus muscle radiodensity and compared them with the MRI findings. Results and conclusion. Significant concordances (P<0.001) were found between the assessments of the superior contour and the heterogeneity of the muscle radiodensity, respectively, on plain radiographs and MR images. For the diagnosis of a full-thickness tear, the analysis of the superior contour and the heterogeneity of the muscle radiodensity reached an accuracy of 85% and 80% respectively. Stepwise discriminant analyses showed low to moderate benefit of considering the contour and the heterogeneity simultaneously. The inter- and intraobserver agreement ranged from moderate to good. We conclude that on the outlet view, modifications in the superior contour and heterogeneity of the supraspinatus muscle radiodensity suggest a full-thickness tear. Received: 6 December 1999 Revision requested: 6 March 2000 Revision received: 5 June 2000 Accepted: 4 October 2000  相似文献   
99.
Oxygen-derived free radicals and intracellular calcium overload have been implicated as mediators of myocardial ischemia/reperfusion injury. We hypothesized that free radical scavengers or calcium channel blockers could enhance the protection afforded the isolated, working rat heart by crystalloid cardioplegia against this type of injury at 37 degrees C. Hearts from 42 male rats in seven groups (n = 6) were studied in an isolated, working heart preparation measuring aortic flow (ml/min/gm dry wt), peak systolic pressure (mm Hg), coronary artery flow (ml/min/gm dry wt), and calculated coronary vascular resistance (dyne.sec.cm-5/gm dry wt). Creatine kinase and lactate dehydrogenase release were measured before ischemia and at various times during the postischemic reperfusion period. Time-matched control hearts (group 1) were perfused for 2 hours. After finding that 30 minutes of ischemia and 10 minutes of reperfusion (group 2) produced significant (p less than 0.01) functional impairment that was completely protected (group 3) by a preischemic bolus of St. Thomas' Hospital cardioplegic solution, we again found significant (p less than 0.01) functional impairment after 40 minutes of ischemia and 10 minutes (group 4) or 20 minutes (group 5) of reperfusion despite a preischemic bolus of St. Thomas' Hospital cardioplegic solution. Diltiazem (10 mg/L) plus St. Thomas' Hospital cardioplegic solution (group 6) did not significantly (p less than 0.01) enhance functional recovery. Addition of superoxide dismutase plus catalase (200 microns/ml) (group 7) produced marked improvement in functional recovery that did not differ significantly (p less than 0.01) from control results (group 1). The creatine kinase and lactate dehydrogenase data strongly supported the preceding functional data. Coronary flow and vascular resistance were not significantly (p less than 0.01) changed from control values in any group. We conclude that the addition of superoxide dismutase and catalase but not diltiazem to St. Thomas' Hospital cardioplegic solution can significantly enhance myocardial protection against normothermic ischemia/reperfusion injury. This implicates oxygen-derived free radicals as mediators of this type of injury.  相似文献   
100.
Mycosis fungoides is a cutaneous T-cell lymphoma (CTCL) usually observed in mid to late adulthood. It occurs only rarely during childhood. Follicular mucinosis is a chronic dermatosis involving the sebaceous glands and outer root sheaths. It is normally differentiated into a juvenile benign form and an adult form possibly associated with mycosis fungoides. We report a 12-year-old boy who presented with an 8-month history of erythematous mucinous plaques on the scalp. Three months later, he developed erythematous patches and plaques on his whole body, accompanied by cervical lymphadenopathy. A biopsy showed follicular mucinosis and epidermotropism of the lymphocytic infiltrate. Immunophenotyping and a PCR clonality test were consistent with CTCL. The patient received PUVA treatment and local steroids, resulting in partial remission. Mycosis fungoides should be considered in the differential diagnosis of chronic, scaling dermatoses in childhood. Moreover, follicular mucinosis in childhood can be associated with mycosis fungoides.  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