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   7906篇
  免费   542篇
  国内免费   32篇
耳鼻咽喉   90篇
儿科学   294篇
妇产科学   166篇
基础医学   841篇
口腔科学   179篇
临床医学   603篇
内科学   1874篇
皮肤病学   181篇
神经病学   501篇
特种医学   233篇
外科学   1629篇
综合类   122篇
一般理论   2篇
预防医学   291篇
眼科学   248篇
药学   638篇
中国医学   35篇
肿瘤学   553篇
  2023年   75篇
  2022年   170篇
  2021年   385篇
  2020年   208篇
  2019年   262篇
  2018年   371篇
  2017年   238篇
  2016年   286篇
  2015年   262篇
  2014年   417篇
  2013年   464篇
  2012年   757篇
  2011年   709篇
  2010年   392篇
  2009年   353篇
  2008年   428篇
  2007年   451篇
  2006年   396篇
  2005年   334篇
  2004年   253篇
  2003年   192篇
  2002年   173篇
  2001年   55篇
  2000年   67篇
  1999年   66篇
  1998年   39篇
  1997年   34篇
  1996年   30篇
  1995年   30篇
  1994年   22篇
  1993年   22篇
  1992年   62篇
  1991年   49篇
  1990年   36篇
  1989年   40篇
  1988年   45篇
  1987年   36篇
  1986年   41篇
  1985年   40篇
  1984年   22篇
  1983年   22篇
  1982年   11篇
  1981年   18篇
  1979年   20篇
  1978年   14篇
  1977年   13篇
  1976年   10篇
  1975年   11篇
  1974年   7篇
  1973年   10篇
排序方式: 共有8480条查询结果,搜索用时 9 毫秒
1.
A total of 131 patients with old (over 6 months) myocardial infarction (MI) and 18 normal subjects underwent equilibrium radionuclide angiocardiography at rest (rERNA). The following rERNA parameters were assessed: left ventricular ejection fraction (LVEF), peak ejection rate (PER), peak filling rate (PFR), regional wall motion and a left ventricular size index. The patients with old MI were divided into four groups (I to IV) according to increasing left ventricular (LV) size, and the behaviour of the numerical parameters (LVEF, PER, PFR) was evaluated in each group. LVEF proved to be the most sensitive numerical parameter of overall LV performance. PFR decreased significantly from group I to group III but not from group III to group IV, suggesting that for extreme degrees of left ventricular enlargement some compensatory mechanism acts to prevent a too large fall in LV compliance. The effects of the site of the previous MI on LV performance were also evaluated. Both LV size and performance were least affected by postero-inferior MI. The LVEF was, however, a better predictor of LV size than the site of the MI.  相似文献   
2.
Nocturnal Sleep‐Related Eating Disorder (NSRED) is a well‐documented sleeping disorder where the person is reported to experience bizarre eating behavior during sleep. Although various causes are implicated in this disorder, role of drugs cannot be ruled out. Here we narrate an interesting rare case report of a drug‐induced new onset NSRED, where a 45‐year‐old man on zolipdem performed an unexpected and bizarre eating behavior during somnambulistic state, type of which has not been reported earlier in the literature. The case falls under even rarer category as such behavior in sleep is reported mainly in woman. © 2008 by Wiley Periodicals, Inc. Int J Eat Disord 2009  相似文献   
3.
Akt, a Serine/Threonine protein kinase, mediates growth factor-associated cell survival. Constitutive activation of Akt (phosphorylated Akt, P-Akt) has been observed in several human cancers, including lung cancer and may be associated with poor prognosis and chemotherapy and radiotherapy resistance. The clinical relevance of P-Akt in non-small cell lung cancer (NSCLC) is not well described. In the present study, we examined 82 surgically resected snap-frozen and paraffin-embedded stage I to IIIA NSCLC samples for P-Akt and Akt by Western blotting and for P-Akt by immunohistochemistry. P-Akt protein levels above the median, measured using reproducible semiquantitative band densitometry, correlated with a favorable outcome (P = 0.007). Multivariate analysis identified P-Akt as a significant independent favorable prognostic factor (P = 0.004). Although associated with a favorable prognosis, high P-Akt levels correlated with high tumor grade (P = 0.02). Adenocarcinomas were associated with low P-Akt levels (P = 0.039). Akt was not associated with either outcome or clinicopathologic variables.Cytoplasmic (CP-Akt) and nuclear (NP-Akt) P-Akt tumor cell staining was detected in 96% and 42% of cases, respectively. Both CP-Akt and NP-Akt correlated with well-differentiated tumors (P = 0.008 and 0.017, respectively). NP-Akt also correlated with nodal metastases (P = 0.022) and squamous histology (P = 0.037).These results suggest P-Akt expression is a favorable prognostic factor in NSCLC. Immunolocalization of P-Akt, however, may be relevant as NP-Akt was associated with nodal metastases, a known poor prognostic feature in this disease. P-Akt may be a potential novel therapeutic target for the management of NSCLC.  相似文献   
4.
Background: Ingestion of coins is a common clinical problem in children. Many of the coins are ferromagnetic and can be retrieved with the help of a magnet. We describe the use of a novel endoscopic accessory for removing ferromagnetic coins. Material and methods: Two magnet discs of 1.5 cm diameter were joined to a 200 cm steel wire of 0.75 mm thickness with a terminal 5 cm spring. A Teflon tube (160 cm, 7 F) was used along with this instrument as a sleeve. The use of this accessory was analyzed prospectively in subjects presenting with a history of coin ingestion. The time taken for removal of coins, complications during the procedure and failure rate was noted. Effect of the magnet on cardiac rhythm was also noted during the procedure. Results: A total of 55 children (mean age 5.1 ± 2.3 years) with coin ingestion presented over a period of 1 year. Forty‐four coins were ferromagnetic. All ferromagnetic coins were removed successfully. Mean time for removal was 68 ± 22 s. No complications were encountered. Conclusion: The novel magnetic instrument is precise, safe and quick for the removal of ferromagnetic coins under direct vision.  相似文献   
5.
Summary: This study compares the outcomes of 229 renal transplants, of which 156 were live related renal transplants done at our centre and 73 unrelated transplants done at other centres but followed up at our centre. All the patients were on triple immunosuppression for periods varying between 9 months and 1 year. Patient characteristics, rejections, infections and 1 and 5 years patient and graft survival were analyzed in the two groups. the outcome of patients who continued on cyclosporine beyond 1 year was compared to those who discontinued cyclosporine at 1 year. Males predominated (191 vs 38) in both groups, while younger patients (<50 years) predominated in live related group (152 vs four). There was no difference in the incidence of infection, rejection, graft dysfunction, graft loss or death between the two groups. the 1 and 5 year patient survival in the related and unrelated group, (93.7% and 71.4% vs and 85% and 66%) and graft survival (90.4% and 69.4% vs 83.3% and 65.4%) were similar. However, in the unrelated group, patients who discontinued cyclosporine had a higher incidence of rejections (38% vs 14%) and graft loss (43% vs 11.8%), while in the related group no such difference was found. It is concluded that 1 and 5 year patient and graft survival is comparable between live related and live unrelated transplantation. However, in the unrelated group it is necessary to continue cyclosporine beyond 1 year in order to achieve comparable results.  相似文献   
6.
PURPOSE: Type I IFNs (IFN-alpha/beta) have shown significant antitumor activity in preclinical models but limited efficacy and significant toxicity in clinical trials. We hypothesized that the antitumor activity of type I IFNs could be enhanced by chronic, low-dose systemic delivery and sought to test this in murine neuroblastoma models. EXPERIMENTAL DESIGN: Continuous liver-generated expression of human IFN-beta (hINF-beta) was achieved through a gene therapy-mediated approach using adeno-associated virus vectors encoding hIFN-beta (AAV hINF-beta). Orthotopic localized retroperitoneal and disseminated models of neuroblastoma were established using three different xenografts. Immunohistochemical analysis and ELISA were used to evaluate the antiangiogenic effect of therapy. RESULTS: The development of both localized orthotopic (retroperitoneal) and disseminated neuroblastoma was prevented in all mice expressing hINF-beta. Continued growth of established retroperitoneal tumors, treated with AAV hINF-beta as monotherapy, was significantly restricted, and survival for mice with established, disseminated disease was significantly prolonged following administration of AAV hINF-beta. Analysis of treated tumors revealed a significant antiangiogenic effect. Mean intratumoral vessel density was diminished and expression of the angiogenic factors vascular endothelial growth factor and basic fibroblast growth factor were both decreased. Finally, combination therapy in which AAV hIFN-beta was used together with low-dose cyclophosphamide resulted in regression of both established retroperitoneal and disseminated disease. CONCLUSIONS: AAV-mediated delivery of hIFN-beta when used as monotherapy was able to restrict neuroblastoma growth due in part to inhibition of angiogenesis. When used in combination with conventional chemotherapy, AAV hIFN-beta was able to effect complete tumor regression.  相似文献   
7.
Summary. The study was conducted to evaluate the diverse effect and clinical significance of TEST yolk buffer treatment on sperm samples of 128 infertile men. Sperm samples were incubated with TEST yolk buffer and control medium (Ham's F-10) at room temperature for 2 h. The hemizona indices (mean ± SE) of the TEST yolk buffer and medium-treated sperm samples were 29 ± 2.3% and 22 ± 1.6%, respectively. Inspection of the individual response of each sperm sample to TEST yolk buffer revealed that 63 samples (49%) improved (double the interassay variation = 28%) their binding to zona pellucida, 36 (28%) remained unchanged, whereas the binding capacity of 29 samples (23%) decreased. Furthermore, TEST yolk buffer treatment of 24 samples (19%) resulted in an increased binding beyond the hemizona index threshold set up at 23%. This level was previously shown to be the cut-off point between fertile and infertile sperm samples. It was concluded that when applied to an unselected group of infertile men, TEST yolk buffer significantly increased sperm binding capacity to the zona pellucida. However, only 19% of the sperm samples showed improvement with clinical significance. The other sperm samples may have improved, remained unchanged or even deteriorated independently on basic sperm variables. Thus, the effect of TEST yolk buffer treatment on sperm binding should be tested prior to its clinical use to avoid possible damage to certain sperm samples.  相似文献   
8.
Acute severe combined demyelination   总被引:2,自引:0,他引:2  
We present a second case in which Guillain-Barré syndrome (GBS) and acute disseminated encephalomyelitis (ADEM) appeared simultaneously, both in acute and fulminant form. The patient, a 10-year-old girl, presented with acute onset of coma and flaccid, areflexic quadriparesis. The elevated CSF protein levels and delayed F waves fulfilled the criteria of GBS and an MRI study revealed extensive multifocal demyelination compatible with a diagnosis of ADEM. Prompt clinical response followed by complete recovery was achieved by treatment with corticosteroids. It is suggested that acute severe combined demyelination might constitute a separate entity in which the demyelinating process, involving simultaneously the central and the peripheral nervous systems, indicates immune response against a component of the myelin of one system carrying cross-antigenicity with the other.  相似文献   
9.
Summary.  Sperm penetration into the zona pellucida of unfertilized oocytes, and its correlation with in vitro fertilization rates of the sibling oocytes, were assessed. This was performed in order to evaluate the prediction rate of the sperm penetration test into the zona pellucida. Unfertilized oocytes ( n =1872) from 371 cycles were pipetted through a microcapillary, and the remaining sperm cells penetrating the zona pellucida were counted. The mean (±SD) number of spermatozoa that penetrated the zona pellucida of unfertilized oocytes was 12.9±16.37. A significant correlation was found between the fertilization rate and the mean number of spermatozoa that penetrated into the zona pellucida of the unfertilized sibling oocytes (r = 0.48; P < 0.001), or the percent of unpenetrated zonae pellucidae in a cohort (r= —0.43; P < 0.001). However, a distinct variation in the number of spermatozoa that penetrated into the zona pellucida was detected. A step-wise regression analysis proved the number of spermatozoa penetrating the zona pellucida to be more predictive for fertilization rates than the variable of percent of unpenetrated zonae pellucidae. The results imply that although there is interdependence between penetration into the zona pellucida and fertilization rate, the predictive value of sperm penetration test for prognosis and future management after the first in vitro fertilization attempt, is limited.  相似文献   
10.
The standard treatment for patients with advanced ovarian cancer (AOC) has been cyclophosphamide and cisplatin (CP). Recently, the results of a large randomized comparative trial demonstrated that the combination of paclitaxel and cisplatin (TP) provided a progression-free survival benefit of 5 months. In this study, a cost–utility analysis was performed from a Canadian health care system perspective to estimate the incremental cost-effectiveness of the TP combination. Twelve AOC patients who received treatment with TP were matched for age and disease stage on a 1-to-2 basis with a CP control. Total hospital resource consumption was then collected for all patients. Treatment preferences were estimated from a cohort of 20 patients and 40 healthy female volunteers using the time trade-off technique. The outcomes were then generated through a decision-analytic model. First-line treatment costs with TP were approximately fourfold greater on a per-cycle basis than the CP alternative (Can$1911 vs Can$459). When progression-free survival benefit and patient treatment preferences were incorporated into the analysis, the results of the decision model revealed an incremental cost between Can$12,000 and Can$24,000 per quality-adjusted progression-free year with the TP protocol. Even though the TP combination has a considerably higher drug acquisition cost, the results of the current analysis suggest that this new chemotherapy regimen does provide patients with substantial quality-adjusted progression-free survival benefit at a reasonable cost to the Canadian health care system.  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