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   2288篇
  免费   154篇
  国内免费   3篇
耳鼻咽喉   16篇
儿科学   51篇
妇产科学   18篇
基础医学   415篇
口腔科学   49篇
临床医学   186篇
内科学   488篇
皮肤病学   43篇
神经病学   253篇
特种医学   49篇
外科学   223篇
综合类   3篇
预防医学   185篇
眼科学   20篇
药学   196篇
中国医学   6篇
肿瘤学   244篇
  2024年   1篇
  2023年   21篇
  2022年   41篇
  2021年   68篇
  2020年   33篇
  2019年   77篇
  2018年   78篇
  2017年   43篇
  2016年   54篇
  2015年   95篇
  2014年   98篇
  2013年   146篇
  2012年   199篇
  2011年   213篇
  2010年   108篇
  2009年   127篇
  2008年   173篇
  2007年   172篇
  2006年   152篇
  2005年   152篇
  2004年   136篇
  2003年   110篇
  2002年   68篇
  2001年   5篇
  2000年   5篇
  1999年   14篇
  1998年   18篇
  1997年   10篇
  1996年   4篇
  1995年   5篇
  1994年   4篇
  1993年   2篇
  1992年   5篇
  1987年   1篇
  1984年   1篇
  1983年   1篇
  1981年   3篇
  1977年   1篇
  1976年   1篇
排序方式: 共有2445条查询结果,搜索用时 15 毫秒
151.
A growing number of patients, mainly cisplatin-pretreated, require second-line therapy for non-small cell lung cancer (NSCLC) but the optimal treatment and appropriate criteria for patient selection have not been defined yet. A second-line phase II study was conducted in cisplatin-pretreated patients with advanced NSCLC to evaluate the activity and toxicity of weekly paclitaxel. Fifty-three consecutive NSCLC patients (9 stage IIIA-B, 44 stage IV) progressing after one front line cisplatin-based chemotherapy were enrolled. Previous treatment with taxanes was not allowed. Patients with stage III were also pretreated with thoracic radiotherapy. Weekly paclitaxel was administered as 1-h infusion at a dose of 80 mg/m(2) for three weeks with one week off, for a maximum of four courses. All patients were assessable for response, toxicity and survival. A complete response was observed in one case, partial response in 7, for an overall response rate (RR) of 15%, (95% Cl = 5-25%). Stable disease (SD) was registered in 11 patients, for an overall clinical benefit (CB = RR + SD) of 36% (95% Cl = 23-49%). Toxicity was mild, with G3-4 neutropenia and thrombocytopenia in 6 and 2% of patients, respectively. Non-hematological toxicities were negligible. No significant correlation between patient or treatment-related variable and RR was observed. CB was significantly higher in patients with non-squamous histology (P = 0.03) and no progression within 4 months of first line cisplatin-based chemotherapy (P = 0.007). Median progression-free survival (PFS) was 7 months in responders and 4 months in pts with SD. PFS was significantly related to good performance status (PS) (P = 0.002) and non-squamous histology (P = 0.004). In conclusion, weekly paclitaxel has acceptable palliative activity and excellent tolerance in cisplatin-pretreated patients. Patients with PS 0-1, non-squamous histology and with no progression within 4 months of first line cisplatin-based chemotherapy seem more likely to benefit from this treatment.  相似文献   
152.
In the present study, the telomerase activity and the putative alterations of genes involved in cell-cycle control (p53, Fas and pRb) were investigated in a radiation-induced meningioma with multiple recurrences and pleural-pulmonary metastases (the patient, a 34-year-old male, had a history of carcinoma of the tongue of testicular lymphocytic lymphoma). Expression of VEGF and vasculature pattern were also studied. Expression of VEGF, pRb and p53 were evaluated by immunohistochemistry on formalin-fixed, paraffin-embedded samples of the tumor. VEGFmRNA was determined by competitive PCR. Fas, FasL and hTERT were evaluated by RT-PCR. Telomerase activity was examined by the TRAP assay. An intense vascularization was observed, supported by high expression of VEGFmRNA (isoforms 121 and 165). pRb and p53 were overexpressed. Fas was undetectable with PCR, whereas FasL was positive. Furthermore, the lesion showed an elevated telomerase activity (TPG, 22), according to the high expression of hTERT. These findings emphasized that even among generally benign neoplasms, such as meningiomas, some highly malignant tumors may develop, as in our case, in which several mechanisms were activated in the cancer progression to guarantee the immortalization of cellular clones (angiogenic phenomenon, activation of telomerase and of anti-apoptotic mechanisms) and the blood spread. Thus, the data illustrate the importance of searching for genetic aberrations (which are a hallmark of malignancy) in meningiomas, as predictive and reliable factors of the possibility to recur and to metastasize.  相似文献   
153.
Neuroblastoma (NB) is a childhood neoplasm which heterogeneous behavior can be explained by differential regulation of apoptosis. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) selectively induces rapid apoptosis in most tumor cells and thus represents a promising anticancer agent. We have reported silencing of caspase-8 expression in highly malignant NB cells as a possible mechanism of resistance to TRAIL-induced apoptosis. To explore the particular contribution of caspase-8 in such resistance, retroviral-mediated stable caspase-8 expression was induced in the IGR-N91 cells. As a result, sensitivity to TRAIL was fully restored in the caspase-8-complemented cells. TRAIL-induced cell death could be further enhanced by cotreatment of IGR-N91-C8 and SH-EP cells with cycloheximide or subtoxic concentrations of chemotherapeutic drugs in a caspase-dependent manner. Sensitization to TRAIL involved enhanced death receptor DR5 expression, activation of Bid and the complete caspases cascade. Interestingly, combined treatments also enhanced the cleavage-mediated inactivation of antiapoptotic molecules, XIAP, Bcl-x(L) and RIP.Our results show that restoration of active caspase-8 expression in a caspase-8-deficient NB cell line is necessary and sufficient to fully restore TRAIL sensitivity. Moreover, the synergistic effect of drugs and TRAIL results from activation of the caspase cascade via a mitochondrial pathway-mediated amplification loop and from the inactivation of apoptosis inhibitors.  相似文献   
154.
To know the prevalence of celiac disease (CD) in a group of children and adolescents with type I diabetes mellitus. A cross sectional study was conducted at the Instituto Materno Infantil de Pernambuco (IMIP) in March 2000. The sample consisted of 19 children and adolescents with type I diabetes mellitus that had the human anti-tissue transglutaminase antibodies assessed using kits from the Eurospital Laboratory. In case of positive results it was realized small intestine biopsy to confirm the diagnosis. For the calculation of the prevalence of CD it was considered the number of patients with serum positive histological alterations of the mucous membrane of the small intestine compatible with CD. Four patients presented serum positivity for human anti-tissue transglutaminase antibodies with a serum prevalence of 21% (4/19). Out of these four subjects, three who accomplished small intestine biopsy presented histological alterations compatible with CD. The prevalence of CD in this group was 15.8% (3/19). The prevalence of CD in this study group was high, suggesting that those with type I diabetes mellitus should be led as a group of high risk to develop this disease.  相似文献   
155.
OBJECTIVE: Restless legs syndrome (RLS) is a common neurologic condition characterized by uncomfortable and unpleasant sensations in the legs, occurring primarily at rest, which are usually worse in the evening and are alleviated by movement. RLS is present in 20-40% of patients with renal failure. This study was a 14-week open, randomized, crossover trial of ropinirole vs. levodopa sustained release (SR) in 11 patients with RLS on chronic hemodialysis. METHODS: Eleven patients (7 men, 4 women) were enrolled in the study. They received either levodopa SR or ropinirole for 6 weeks, followed by a washout week, then the alternate treatment for 6 weeks. Patients rated the severity of RLS by means of a 6-item questionnaire developed by the International Restless Legs Study Group (6-item IRLS), by the Clinical Global Impression (CGI) scale, and by sleep diaries. RESULTS: Under treatment with levodopa SR, 1 patient presented severe vomiting, leading to study discontinuation. The 10 patients who completed the study reported a 33.5% improvement (from 16.7 +/- 3.2 to 11.1 +/- 4; P < 0.001) of the 6-item IRLS scores during levodopa SR treatment and a 73.5% improvement (from 16.6 +/- 2.8 to 4.4 +/- 3.8; P < 0.001) during ropinirole treatment. By the end of the study the mean levodopa SR dosage was 190 mg/d and the mean ropinirole dosage was 1.45 mg/d. Ropinirole was superior to levodopa SR in reducing 6-item IRLS scores (P < 0.001) and in increasing sleep time (P < 0.001). The patient CGI scale showed a significant difference favoring ropinirole (P < 0.01). There was no significant carryover or period effect for any outcome measure. Four patients reported a complete reversion of RLS symptoms during ropinirole treatment at doses ranging from 0.25-2 mg/d. CONCLUSIONS: These results suggest that ropinirole is more effective than levodopa SR in the treatment of RLS in patients on chronic hemodialysis.  相似文献   
156.
In humans, the caudal pole of the superior parietal lobule is involved in the control of both reaching and grasping movements, whereas in monkey it is reported to be involved only in the control of reaching. Using single-unit recordings from trained macaque monkeys, we investigated whether area V6A, a visuomotor area located in the caudal part of the posterior parietal cortex, is involved in both components of prehension, the hand transport towards the visual target and the grip formation to secure the grasp. In Experiment 1, neural activity was recorded in V6A while two monkeys performed two instructed-delay reaching tasks (reach-to-point and reach-to-grasp) under controlled conditions in darkness. Fourty-five of 93 tested neurons (48%) were modulated during reach-to-point and 62% (52/84) during reach-to-grasp. In 63% of cells (51/81) neural activity was significantly different between reach-to-point and reach-to-grasp tasks, suggesting that grip formation could influence neural activity. In Experiment 2, two monkeys performed natural reach-to-grasp movements in fully lit environment; V6A neural activity and arm-hand movements were recorded by a digital camcorder and analysed frame-by-frame using a digital video technique. Thirty of the 58 tested neurons (52%) were modulated during natural prehension; about 30% of these neurons (8/30) were modulated only during the last phase of prehension, i.e. during finger flexion around the object to be grasped. This is the first direct demonstration that both reaching and grasping modulate neural activity in the caudal part of the posterior parietal cortex of the macaque. Our work suggests a strict functional homology between human and monkey superior parietal lobule.  相似文献   
157.
158.
BACKGROUND: The long-term effects of liver transplantation (LT) on minimal hepatic encephalopathy are poorly documented. OBJECTIVE: To assess the cognitive performance of patients with cirrhosis and without overt encephalopathy, before and after LT. DESIGN: Longitudinal study comparing cognitive performance of patients with cirrhosis before LT and 6 to 18 months after LT, with matched control patients. SETTING: University medical center. RESULTS: Six months after LT, patients had improved their performance in visuospatial and selective attention, visuospatial short-term and long-term memory, and language tasks. After 18 months, a further improvement was found for selective attention and verbal short-term memory, while no other cognitive functions varied over time. CONCLUSIONS: The present findings confirm preliminary studies showing that LT improves cognitive functions in patients with cirrhosis. The cognitive improvement is not generalized, but appears prominent in attention and memory and, once achieved, remains stable. Rates of recovery differ, being early for some functions and later for others.  相似文献   
159.
160.
It is difficult to envision anything better than melanoma vaccines to exemplify the effectiveness of modern biotechnology in developing biologically rational therapeutics. Melanoma vaccines can reproducibly induce cytotoxic T lymphocyte (CTL) responses better than any other anticancer therapy. Anticancer vaccines have been labeled by some as ineffective for the simple reason that they only rarely lead to cancer regression. This oxymoron stems from the naïve expectation that CTLs are all that is needed to reject cancer. Little is known about requirements for CTL localization and effector function within the tumor microenvironment. In the future, more attention should be given to events downstream of immunization (afferent arm of immune response) to identify combination therapies likely to facilitate localization and activation of CTL at the receiving end (efferent arm).  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