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   1440篇
  免费   92篇
  国内免费   9篇
耳鼻咽喉   22篇
儿科学   33篇
妇产科学   24篇
基础医学   132篇
口腔科学   25篇
临床医学   101篇
内科学   283篇
皮肤病学   52篇
神经病学   125篇
特种医学   55篇
外科学   292篇
综合类   37篇
一般理论   2篇
预防医学   77篇
眼科学   62篇
药学   122篇
中国医学   1篇
肿瘤学   96篇
  2023年   11篇
  2022年   22篇
  2021年   47篇
  2020年   26篇
  2019年   48篇
  2018年   42篇
  2017年   35篇
  2016年   33篇
  2015年   49篇
  2014年   64篇
  2013年   91篇
  2012年   123篇
  2011年   107篇
  2010年   63篇
  2009年   49篇
  2008年   80篇
  2007年   73篇
  2006年   65篇
  2005年   72篇
  2004年   77篇
  2003年   61篇
  2002年   48篇
  2001年   31篇
  2000年   32篇
  1999年   19篇
  1998年   7篇
  1997年   6篇
  1996年   9篇
  1995年   4篇
  1994年   2篇
  1993年   4篇
  1992年   27篇
  1991年   18篇
  1990年   14篇
  1989年   13篇
  1988年   9篇
  1987年   10篇
  1986年   4篇
  1985年   2篇
  1980年   3篇
  1978年   2篇
  1977年   8篇
  1976年   3篇
  1975年   4篇
  1974年   4篇
  1973年   4篇
  1972年   5篇
  1969年   2篇
  1965年   1篇
  1930年   1篇
排序方式: 共有1541条查询结果,搜索用时 15 毫秒
991.
Chondrocytes of the epiphyseal growth plate (physis) differentiate and mature in defined linear zones. The current study examines the differentiation of human bone marrow derived mesenchymal stem cells (hBMSCs) into zonal physeal cartilage. hBMSCs were embedded in an agarose scaffold with only the surface of the scaffold in direct contact with the culture medium. The cells were differentiated using a two‐step system involving the sequential addition of TGFβ followed by BMP2. The resultant samples displayed a heterogenic population of physis‐like collagen type 2 positive cells including proliferating chondrocytes and mature chondrocytes showing hypertrophy, expression of early bone markers and matrix mineralization. Histological analysis revealed a physis‐like linear zonal alignment of chondrocytes in varying stages of differentiation. The less mature chondrocytes were seen at the base of the construct while hypertrophic chondrocytes and matrix mineralization was observed closer to the surface of the construct. The described differentiation protocol using hBMSCs in an agarose scaffold can be used to study the factors and conditions that influence the differentiation, proliferation, maturation, and zonal alignment of physeal chondrocytes. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1753–1759, 2012  相似文献   
992.
993.
This study examined the role of hypnotic responsiveness in the practice of a dhami-jhankri, a traditional Nepali healer. The hypnotic capacity of 248 male patients was measured in an allopathic (Western) clinic, an Ayurvedic (ancient Hindu healing art) clinic, and a dhami-jhankri's practice. Hypnotizability was assessed using the Hypnotic Induction Profile (HIP). The Induction scores of the HIP were significantly higher among the dhami-jhankri's patients than among either the Ayurvedic or allopathic patients. Furthermore, patients who returned to the dhami-jhankri were more highly hypnotizable than first-time dhami-jhankri patients. In addition, treatment satisfaction as reported by dhami-jhankri patients was positively correlated with HIP scores. The authors conclude that hypnotic phenomena as measured in the West might be an important component of the dhami-jhankri's treatment in the East.  相似文献   
994.
995.
Transcatheter aortic valve implantation (TAVI) has become the standard of care for inoperable patients with symptomatic severe aortic stenosis (AS), and an alternative to open aortic valve replacement for patients at high surgical risk. TAVI has also been performed in several groups of patients with off-label indications such as severe bicuspid AS, and as a valve-in-valve therapy for a degenerated surgical bioprosthesis. Although TAVI with CoreValve® prosthesis is technically challenging, and global experience in the procedure is limited, the procedure could be a treatment option for well-selected patients with severe pure aortic regurgitation (AR). Herein, we report Asia''s first case of TAVI for severe pure AR in a patient who was at extreme surgical risk, with good clinical outcome at six months.  相似文献   
996.
BACKGROUND: The optimal treatment for early prostate cancer has yet to be established. A well-tolerated hormonal therapy such as bicalutamide could be a useful treatment option in this setting, either as adjuvant or immediate therapy. A major collaborative clinical trials program was set up to investigate bicalutamide as a treatment option for local prostate cancer (localized or locally advanced disease). METHODS: The bicalutamide Early Prostate Cancer program comprises three randomized, double-blind, placebo-controlled trials of similar design that are being conducted in distinct geographical areas (North America; Australia, Europe, Israel, South Africa and Mexico; and Scandinavia). Men with T1b-4N0-1M0 (TNM 1997) prostate cancer have been randomized on a 1:1 basis to receive bicalutamide 150 mg daily or placebo. Recruitment to the program closed in July 1998, and follow-up is ongoing. Study endpoints include time to clinical progression, overall survival and tolerability. RESULTS: 8113 men aged 38 to 93 years (mean 66.9) were randomized over a 3-year period. 67.4% of the enrolled patients had localized disease (T1-2) and 66.4% had a Gleason score 相似文献   
997.
We report a high-yield single-step method for synthesizing nitrogen-doped graphene nanostripes (N-GNSPs) with an unprecedentedly high percentage of pyridinic-type doping (>86% of the nitrogen sites), and investigate the performance of the resulting N-GNSPs as a lithium-ion battery (LIB) anode material. The as-grown N-GNSPs are compared with undoped GNSPs using scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), helium ion-beam microscopy (HIM), and electrochemical methods. As an anode material we find that pyridinic-type N-GNSPs perform similarly to undoped GNSPs, suggesting that pyridinic sites alone are not responsible for the enhanced performance of nitrogen-doped graphene observed in previous studies, which contradicts common conjectures. In addition, post-mortem XPS measurements of nitrogen-doped graphene cycled as a lithium-ion battery anode are conducted for the first time, which reveal direct evidence for irreversible chemical changes at the nitrogen sites during cycling. These findings therefore provide new insights into the mechanistic models of doped graphene as LIB anodes, which are important in improving the anode designs for better LIB performance.

Selectively pyridinic type nitrogen-doped graphene is fabricated and applied as a lithium ion battery anode including post mortem characterization.  相似文献   
998.
Extending the delivery of drugs into the eyes while reducing systemic bioavailability is of utmost importance in the management of chronic ocular diseases. Topical application onto the lower eyelid skin, as an alternative to eye drops, is seen to be a valuable strategy in the treatment of chronic eye diseases. To elucidate the critical value of delivering drugs in solution onto the eyeball through the eyelid skin, pharmacokinetic studies of pilocarpine were conducted, and the results were verified using a direct pharmacodynamic study in rats. The mean residence time of pilocarpine after topical eyelid application to the eyelid skin, conjunctiva, eyeball, and plasma were 14.9, 8.50, 6.29, and 8.11 h, respectively. Conjunctiva and eyeball concentrations of pilocarpine at 8 h were 80-fold and 8-fold higher after topical eyelid application, respectively, than those for eye drops. Pupillary constriction was sustained over 8 h after topical eyelid application. Topical eyelid skin application exhibited a localized drug absorption and specific drug accumulation in the ocular tissues. Hence, it is rational to prepare topical formulations directed onto the eyelid skin, which is suitable for drugs required for long-term treatment.  相似文献   
999.
1000.
Central dopaminergic hyperactivity has been one of the main hypotheses of the pathophysiology of schizophrenia since the 1970s. Excess dopamine (DA) neurotransmission in the striatum is hypothesized to alter the processing of information and result in psychotic symptoms in schizophrenia. Single photon emission computerized tomography (SPECT) provides in vivo indices of DA neurotransmission. Our study aimed to compare dopamine transporter (DAT) availability between drug-naive patients with schizophrenia and controls using SPECT. DAT availability through [99mTc]-TRODAT-1 SPECT was compared between 47 drug-naive patients with recent-onset schizophrenia and 112 healthy controls. We also conducted a random-effects meta-analysis of the available literature synthesizing the results of 6 comparable published articles as well as our current data. The mean specific striatal binding showed a statistical trend for a reduction among the patients compared with controls (estimated difference = 0.071; 95% CI −0.01, 0.15; P = .08). There was an effect of gender, whereby females had a higher ratio of specific striatal binding than males. Age was negatively correlated with the ratio of specific striatal binding, both in patients and controls. The meta-analysis provided a pooled standardized effect size (Cohen’s d) of −0.07 (95% CI −0.31, 0.18; P = .60) for the patient vs control comparison in TRODAT binding, with no evidence of heterogeneity between studies or publication bias. Our findings suggest that striatal DAT levels are not altered in the early stages of schizophrenia before medication is introduced. We identified gender differences and aging effects that could have significance for future studies.  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