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   596篇
  免费   81篇
  国内免费   6篇
耳鼻咽喉   1篇
儿科学   9篇
妇产科学   14篇
基础医学   65篇
口腔科学   4篇
临床医学   45篇
内科学   116篇
皮肤病学   2篇
神经病学   31篇
特种医学   8篇
外科学   43篇
综合类   20篇
一般理论   4篇
预防医学   128篇
眼科学   2篇
药学   90篇
中国医学   17篇
肿瘤学   84篇
  2024年   3篇
  2023年   24篇
  2022年   29篇
  2021年   16篇
  2020年   30篇
  2019年   36篇
  2018年   32篇
  2017年   35篇
  2016年   31篇
  2015年   22篇
  2014年   33篇
  2013年   56篇
  2012年   35篇
  2011年   29篇
  2010年   21篇
  2009年   25篇
  2008年   28篇
  2007年   27篇
  2006年   26篇
  2005年   29篇
  2004年   14篇
  2003年   15篇
  2002年   15篇
  2001年   12篇
  2000年   8篇
  1999年   11篇
  1998年   5篇
  1997年   3篇
  1996年   6篇
  1995年   4篇
  1994年   6篇
  1993年   7篇
  1992年   2篇
  1991年   1篇
  1989年   2篇
  1988年   3篇
  1985年   2篇
排序方式: 共有683条查询结果,搜索用时 15 毫秒
1.
A case of surrogate pregnancy is described in the sister of a 40-year-old hysterectomized woman where two oocytes of the latter were fertilized in vitro with known donor sperm and transferred into the surrogate. A normal singleton pregnancy developed which was complicated after 24 weeks of gestation with recurrent antepartum hemorrhages due to grade 3 placenta praevia. A healthy female baby was delivered by elective cesarean section at 36 weeks of gestation. The legal, social, psychological, and ethical issues of surrogacy remain unsettled and are discussed in this case report.  相似文献   
2.
3.
The purpose of our study was to review and evaluate retrospectively the experience of an in-vitro fertilization (IVF) surrogate gestational programme in a tertiary care and academic centre. In a 15 year period from 1984 to 1999, a total of 180 cycles of IVF surrogate gestational pregnancy was started in 112 couples. On average, the women were 34.4 +/- 4.4 years of age, had 11.1 +/- 0.72 oocytes obtained per retrieval, 7.1 +/- 0.5 oocytes fertilized and 5. 8 +/- 0.4 embryos subsequently cleaved. Sixteen cycles (8.9%) were cancelled due to poor stimulation. Except for six cycles (3.3%) where there were no embryos available, an average of 3.2 +/- 0.1 embryos was transferred to each individual recipient. The overall pregnancy rate per cycle after IVF surrogacy was 24% (38 of 158), with a clinical pregnancy rate of 19% (30 of 158), and a live birth rate of 15.8% (25 of 158). When compared to patients who underwent a hysterectomy, individuals with congenital absence of the uterus had significantly more oocytes retrieved (P < 0.006), fertilized, cleaved and more embryos available for transfer despite being of comparable age. IVF surrogate gestation is an established, yet still controversial, approach to the care of infertile couples. Take-home baby rates are comparable to conventional IVF over the same 15 year span in our programme. Patients with congenital absence of the uterus responded to ovulation induction better than patients who underwent a hysterectomy, perhaps due in part to ovarian compromise from previous surgical procedures.  相似文献   
4.
刘月  罗云  谭婷  廖正根  杨明 《中草药》2020,51(24):6405-6413
煎煮时间对于保证中药汤剂临床疗效和中成药质量起着至关重要的作用,从古至今,中药汤剂煎煮终点的判断一直是困扰人们的技术难题。对中医药典籍《伤寒论》和《温病条辨》中汤剂的煎煮时间及其煎煮终点的判断经验进行了整理,发现其具有一定的规律,认为影响煎煮时间的因素主要有病证、方剂功效、药物药性、药材性状等;通过对其总结,并结合现代研究成果初步阐明传统中药汤剂煎煮终点的判断方法,以期能为中药汤剂煎煮时间及现代中药制剂的提取工艺寻求合理的科学依据,为保证中药汤剂临床疗效和中药制剂的质量提供理论基础。  相似文献   
5.
6.
《Seminars in oncology》2016,43(4):464-475
Circulating tumor cells (CTCs), which are captured from blood with anti-epithelial cell adhesion molecule (EpCAM) antibodies, have established prognostic value in specific epithelial cancers, but less is known about their utility for assessing patient response to molecularly targeted agents via measurement of pharmacodynamic (PD) endpoints. We discuss the use of CellSearch (Janssen Diagnostics, LLC, Raritan, NJ) CTC isolation technology for monitoring PD response in early phase trials. We present representative data from three clinical trials with the poly(ADP-ribose) polymerase (PARP) inhibitor veliparib (ABT-888) suggesting that CTCs can be used to measure PD effects. However, while often leading to hypothesis-generating information, our experience points to the difficulty in obtaining sufficient EpCAM-expressing CTCs from patients with advanced disease to reach statistically significant conclusions about PD effects from each trial. Overall, the level of phenotypic heterogeneity observed in specimens from patients with advanced carcinomas suggests caution in the use of cell-surface differentiation marker-based methods for isolating CTCs.  相似文献   
7.
《Bulletin du cancer》2014,101(4):E19-E24
BackgroundThe choice of the activity endpoint is crucial when designing phase II screening trials. This choice is usually guided by convention, but the level of evidence for picking-up one of them is limited.MethodsWe have analysed the phase II trials in carcinoma of unknown primary patients (CUP; 48 strata). We calculated the Pearson correlation coefficient using weighted linear regression to measure the degree of association between the different available activity endpoints (Best objective response – BORR, best tumour control rate – BTCR, 3- and 6-month progression-free rates, 3- and 6-month PFR and median progression-free survival). We also explored the correlation between these endpoints and OS.ResultsAll activity endpoints were strongly correlated in CUP studies; all of these endpoints were strongly correlated with OS. The median BORR across the studies was 30%. Positive trials defined by BORR  30% were associated with statistically longer PFS (4.8 versus 3.7 months, P = 0.013) and OS (10.0 versus 8.0, P = 0.0007).DiscussionIn phase II studies with CUP patients, BORR and the threshold of BORR > 30% for defining promising drug appears adequate.  相似文献   
8.
9.
With the advent of novel cancer therapies targeting molecular pathways or the immune system, time-to-event variables evaluated at longer times (e.g., 6 or 12 months) are increasingly used as the primary endpoint in randomized Phase II trials. Two-stage “Simon” designs have often been used in single-group phase II oncology trials to reduce the expected sample size under the null hypothesis. We develop optimal two-stage and three-stage randomized two-group designs with analogous optimality criteria. Accurate implementation of the Simon design can be difficult, and the difficulty increases with a longer-term endpoint, because it requires complete information from each accrued patient. Earlier work of Case and Morgan generalized the Simon design so it can be implemented without an accrual pause. We derive optimal designs that allow a brief preplanned pause (? 0) in accrual before interim analyses to more efficiently use data from the accrued patients, and to allow focused data collection before the interim analyses. We provide software (R package OptInterim) that creates the optimal designs and also simulates their properties to check asymptotic approximations and the robustness of the designs to differing conditions. Various design options are illustrated using an example based on a recent colorectal cancer drug trial.  相似文献   
10.
ObjectivesThe aim of this study was to evaluate the long-term impact of coronary artery calcification (CAC) on outcomes after percutaneous coronary intervention and the respective performance of first- and second-generation drug-eluting stents (DES).BackgroundWhether contemporary DES have improved the long-term prognosis after percutaneous coronary intervention in lesions with severe CAC is unknown.MethodsIndividual patient data were pooled from 18 randomized trials evaluating DES, categorized according to the presence of angiography core laboratory–confirmed moderate or severe CAC. Major endpoints were the patient-oriented composite endpoint (death, myocardial infarction [MI], or any revascularization) and the device-oriented composite endpoint of target lesion failure (cardiac death, target vessel MI, or ischemia-driven target lesion revascularization). Multivariate Cox proportional regression with study as a random effect was used to assess 5-year outcomes.ResultsA total of 19,833 patients were included. Moderate or severe CAC was present in 1 or more target lesions in 6,211 patients (31.3%) and was associated with increased 5-year risk for the patient-oriented composite endpoint (adjusted hazard ratio [adjHR]: 1.12; 95% confidence interval [CI]: 1.05 to 1.20) and target lesion failure (adjHR: 1.21; 95% CI: 1.09 to 1.34), as well as death, MI, and ischemia-driven target lesion revascularization. In patients with CAC, use of second-generation DES compared with first-generation DES was associated with reductions in the 5-year risk for the patient-oriented composite endpoint (adjHR: 0.88; 95% CI: 0.78 to 1.00) and target lesion failure (adjHR: 0.73; 95% CI: 0.61 to 0.87), as well as death or MI, ischemia-driven target lesion revascularization, and stent thrombosis. The relative treatment effects of second-generation compared with first-generation DES were consistent in patients with and without moderate or severe CAC, although outcomes were consistently better with contemporary devices.ConclusionsIn this large-scale study, percutaneous coronary intervention of target lesion moderate or severe CAC was associated with adverse patient-oriented and device-oriented adverse outcomes at 5 years. These detrimental effects were mitigated with second-generation DES.  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