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   3814篇
  免费   188篇
  国内免费   13篇
耳鼻咽喉   110篇
儿科学   145篇
妇产科学   54篇
基础医学   486篇
口腔科学   71篇
临床医学   227篇
内科学   994篇
皮肤病学   49篇
神经病学   323篇
特种医学   117篇
外国民族医学   4篇
外科学   484篇
综合类   16篇
预防医学   249篇
眼科学   50篇
药学   323篇
中国医学   7篇
肿瘤学   306篇
  2023年   25篇
  2022年   43篇
  2021年   87篇
  2020年   58篇
  2019年   76篇
  2018年   91篇
  2017年   73篇
  2016年   69篇
  2015年   95篇
  2014年   105篇
  2013年   129篇
  2012年   209篇
  2011年   236篇
  2010年   133篇
  2009年   114篇
  2008年   214篇
  2007年   216篇
  2006年   179篇
  2005年   166篇
  2004年   153篇
  2003年   123篇
  2002年   128篇
  2001年   107篇
  2000年   86篇
  1999年   89篇
  1998年   30篇
  1997年   34篇
  1996年   26篇
  1995年   33篇
  1994年   24篇
  1993年   20篇
  1992年   60篇
  1991年   52篇
  1990年   53篇
  1989年   56篇
  1988年   53篇
  1987年   54篇
  1986年   42篇
  1985年   30篇
  1984年   24篇
  1983年   27篇
  1981年   22篇
  1979年   36篇
  1978年   15篇
  1975年   17篇
  1974年   22篇
  1973年   18篇
  1971年   18篇
  1970年   14篇
  1968年   16篇
排序方式: 共有4015条查询结果,搜索用时 15 毫秒
971.
A case of isolated cardiac echinococcosis is reported. A 19-year-old man was hospitalized for chest pain with electrocardiographic pathological Q waves in D1, aVL, V5, V6. Two-dimensional echocardiography and chest computed tomography documented pericardial effusion and an intramyocardial cyst. Casoni's reaction and immunological tests completed the diagnosis of cardiac hydatidosis. The localization and the etiology of the cyst were confirmed during cardiac surgery.  相似文献   
972.

Introductions

In the care of hypertension, it is important that health professionals possess available tools that allow evaluating the impairment of the health-related quality of life, according to the severity of hypertension and the risk for cardiovascular events. Among the instruments developed for the assessment of health-related quality of life, there is the Mini-Cuestionario of Calidad de Vida en la Hipertensión Arterial (MINICHAL) recently adapted to the Brazilian culture.

Objective

To estimate the validity of known groups of the Brazilian version of the MINICHAL regarding the classification of risk for cardiovascular events, symptoms, severity of dyspnea and target-organ damage.

Methods

Data of 200 hypertensive outpatients concerning sociodemographic and clinical information and health-related quality of life were gathered by consulting the medical charts and the application of the Brazilian version of MINICHAL. The Mann-Whitney test was used to compare health-related quality of life in relation to symptoms and target-organ damage. The Kruskal-Wallis test and ANOVA with ranks transformation were used to compare health-related quality of life in relation to the classification of risk for cardiovascular events and intensity of dyspnea, respectively.

Results

The MINICHAL was able to discriminate health-related quality of life in relation to symptoms and kidney damage, but did not discriminate health-related quality of life in relation to the classification of risk for cardiovascular events.

Conclusion

The Brazilian version of the MINICHAL is a questionnaire capable of discriminating differences on the health‑related quality of life regarding dyspnea, chest pain, palpitation, lipothymy, cephalea and renal damage.  相似文献   
973.
Nonalcoholic steatohepatitis (NASH) enhances the risk of progressive liver disease. In chronic hepatitis C (CHC), liver steatosis is frequent, especially in genotype 3, but its clinical significance is debated. As squamous cell carcinoma antigen (SCCA)‐IgM has been associated with advanced liver disease and risk of tumour development, we evaluated its occurrence in CHC and the possible relation with NASH at liver biopsy. Using a validated ELISA, serum SCCA‐IgM was measured in 91 patients with CHC at the time of liver biopsy performed before antiviral treatment, at the end of treatment and 6 months thereafter, and in 93 HCV‐negative patients with histological diagnosis of nonalcoholic fatty liver disease, as controls. SCCA‐IgM was detected in 33% of CHC patients and in 4% of controls. This biomarker was found more elevated in CHC patients with histological NASH, and at multivariate analysis, SCCA‐IgM and HCV genotype 3 were independently associated with NASH [OR (95% CI): 6.94 (1.21–40) and 27.02 (4.44–166.6)]. As predictors of NASH, HCV genotype 3 and SCCA‐IgM had a specificity and a sensitivity of 97% and 44%, and of 95% and 27%, respectively. PPV and NPV were 80% and 86% for HCV genotype 3 vs 73% and 72% for SCCA‐IgM. In patients with sustained virologic response to therapy, SCCA‐IgM levels decreased significantly, while these remained unchanged in nonresponders. In conclusion, SCCA‐IgM is detectable in one‐third of patients with CHC and significantly correlates with histological NASH.  相似文献   
974.
To determine the effects of 4-hydroxy-4-androstene-3,17-dione (4-OH-A) on the in vitro conversion of testosterone (T) to 5 alpha-androstan-17 beta-ol-3-one (dihydrotestosterone, DHT), 5 alpha-androstan-3 alpha, 17 beta-diol and 5 alpha-androstan-3 beta, 17 beta-diol (diols), human benign hypertrophic prostatic (BPH) tissue was incubated with 4-14C-T as substrate, in the presence of 4-OH-A (10(-8) to 10(-6) M); the amounts of the 5 alpha-reduced metabolites formed were quantitated. The effects of 4-OH-A were compared with those of 17 beta-N,N-diethylcarbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one (4-MA), a known inhibitor of the 5 alpha-reductase. In the absence of 4-OH-A and 4-MA, human BPH tissue converted T to DHT and the diols readily. Both 4-OH-A and 4-MA induced significant and dose-related decreases in the formation of both DHT and the diols. The degree of inhibition induced by the different concentrations of 4-OH-A and 4-MA were 31, 41, 72% and 57, 87, 97%, respectively. The decreased formation of the diols was a consequence of the decreased availability of DHT (the immediate precursor of the diols) and was not due to direct effects of the inhibitors on the 3-hydroxysteroid dehydrogenases; both 4-OH-A and 4-MA were totally unable to modify the conversion of DHT to the diols, when 4-14C-DHT was used as substrate. Thus, 4-OH-A inhibits the process of 5 alpha-reduction of T in BPH tissue. This molecule might represent a potential new agent for the prevention and/or treatment of human BPH.  相似文献   
975.
Drugs able to mimic or to antagonize the action of catecholamines have been implanted bilaterally into the basomedial region of the amygdala of adult castrated female rats. The animals were killed at different intervals after the implantation of the different drugs, and serum levels of LH and FSH were measured by radioimmunoassay. The results have shown that the intra-amygdalar implantation of the alpha-adrenergic blocker phenoxybenzamine induces a significant increase of the release both of LH and FSH. The implantation of the beta-adrenergic blocker propranolol brings about a rise of LH only. The dopamine receptor blocker pimozide stimulates the release of LH and exerts a biphasic effect (stimulation followed by inhibition) of FSH secretion. The alpha-receptor stimulant clonidine and the dopaminergic drug 2-Br-alpha-ergocryptine were without significant effects. From these observations it is suggested that the adrenergic signals reaching the basomedial area of the amygdala (possibly from the brain stem) may be involved in the modulation of gonadotrophin secretion.  相似文献   
976.
Glucose-6-phosphate dehydrogenase (G6PD; EC 1.1.1.49) deficiency is a common genetic abnormality affecting an estimated 400 million people worldwide. Clinical and biochemical analyses have identified many variants exhibiting a range of phenotypes, which have been well characterized from the hematological point of view. However, until now, their precise molecular basis has remained unknown. We have cloned and sequenced seven mutant G6PD alleles. In the nondeficient polymorphic African variant G6PD A we have found a single point mutation. The other six mutants investigated were all associated with enzyme deficiency. In one of the commonest, G6PD Mediterranean, which is associated with favism among other clinical manifestations, a single amino acid replacement was found (serine----phenylalanine): it must be responsible for the decreased stability and the reduced catalytic efficiency of this enzyme. Single point mutations were also found in G6PD Metaponto (Southern Italy) and in G6PD Ilesha (Nigeria), which are asymptomatic, and in G6PD Chatham, which was observed in an Indian boy with neonatal jaundice. In G6PD "Matera," which is now known to be the same as G6PD A-, two separate point mutations were found, one of which is the same as in G6PD A. In G6PD Santiago, a de novo mutation (glycine----arginine) is associated with severe chronic hemolytic anemia. The mutations observed show a striking predominance of C----T transitions, with CG doublets involved in four of seven cases. Thus, diverse point mutations may account largely for the phenotypic heterogeneity of G6PD deficiency.  相似文献   
977.
BackgroundCataract surgery is the most common operation performed worldwide. A fixed topical corticosteroid-antibiotic combination is usually prescribed in clinical practice for 2 or more weeks to treat post surgical inflammation and prevent infection. However, this protracted schedule may increase the incidence of corticosteroid-related adverse events and notably promote antibiotic resistance.MethodsThis International, multicentre, randomized, blinded-assessor, parallel-group clinical study evaluated the non-inferiority of 1-week levofloxacin/dexamethasone eye drops, followed by 1-week dexamethasone alone, vs. 2-week gold-standard tobramycin/dexamethasone (one drop QID for all schedules) to prevent and treat ocular inflammation and prevent infection after uncomplicated cataract surgery. Non-inferiority was defined as the lower limit of the 95% confidence interval (CI) around a treatment difference >–10%. The study randomized 808 patients enrolled in 53 centres (Italy, Germany, Spain and Russia). The primary endpoint was the proportion of patients without anterior chamber inflammation on day 15 defined as the end of treatment. Endophthalmitis was the key secondary endpoint. This study is registered with EudraCT code: 2018-000286-36.ResultsAfter the end of treatment, 95.2% of the patients in the test arm vs. 94.9% of the control arm had no signs of inflammation in the anterior chamber (difference between proportions of patients = 0.028; 95% CI: −0.0275/0.0331). No case of endophthalmitis was reported. No statistically significant difference was evident in any of the other secondary endpoints. Both treatments were well tolerated.ConclusionsNon-inferiority of the new short pharmacological strategy was proven. One week of levofloxacin/dexamethasone prevents infection, ensures complete control of inflammation in almost all patients and may contain antibiotic resistance.Subject terms: Health care, Drug therapy  相似文献   
978.
Frogs were treated with a single dose of gentamicin administered intraotically to produce severe degeneration of posterior semicircular canal hair cells and to evaluate the time course of functional damage and recovery both at pre- and postsynaptic level. In isolated canal preparations the endoampullar potential, which reflects the summed receptor potentials of crista hair cells, was progressively reduced in amplitude and completely abolished 6 days after gentamicin treatment. At this time the crista epithelium was devoid of hair cells. The recovery of the endoampullar potential began around 9 days after the ototoxic insult and its amplitude progressively increased to reach, after 20 days, values close to those observed in control experiments. The endoampullar potential amplitude was related to the degree of hair cell regeneration in the crista epithelium. Consistent with the presynaptic damage, the slow generator potential (representing the summed miniature excitatory postsynaptic potential [mEPSP] activity of all posterior nerve fibres) and the resting and evoked spike discharge recorded from the whole ampullar nerve were abolished 6 days after gentamicin treatment. The recovery of the background and evoked afferent activity showed different behaviours. Background spike activity became detectable around 8 days after the ototoxic insult, but was not modulated by canal stimulation at this time, and no generator potential was detected. Moreover, the resting spike frequency fully recovered and reached control values around 15 days after gentamicin treatment, whereas the evoked activity attained normal values only 20 days after the ototoxic insult. These results were confirmed by intracellular recordings from single afferent fibres of the ampullar nerve in intact labyrinth preparations. Absence of any resting and evoked discharge was the most common pattern observed in the early period from 7 to 8 days after gentamicin treatment. Fifty-five percent of impaled afferents were silent while the others showed low resting frequencies of mEPSPs and spikes, and were unresponsive to canal rotation. In the intermediate period from 14 to 15 days after gentamicin treatment, background mEPSP and spike frequencies approached those evaluated in control experiments, but the frequencies of the evoked mEPSPs and spikes were clearly lower than in controls. In the late period, from 18 to 20 days after the ototoxic insult, the impaled afferents showed normal evoked mEPSP and spike frequencies. The present data indicate that the frog semicircular canal completely recovers its pre- and postsynaptic activity following severe ototoxic insult. During the regeneration process, the cytoneural junction regains function and the resting discharge reappears before recovery of mechanoelectrical transduction.  相似文献   
979.
980.
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