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   6685篇
  免费   294篇
  国内免费   20篇
耳鼻咽喉   143篇
儿科学   50篇
妇产科学   74篇
基础医学   809篇
口腔科学   135篇
临床医学   457篇
内科学   1737篇
皮肤病学   152篇
神经病学   362篇
特种医学   438篇
外科学   1099篇
综合类   30篇
预防医学   227篇
眼科学   69篇
药学   542篇
中国医学   39篇
肿瘤学   636篇
  2022年   25篇
  2021年   87篇
  2020年   53篇
  2019年   80篇
  2018年   102篇
  2017年   89篇
  2016年   110篇
  2015年   106篇
  2014年   141篇
  2013年   177篇
  2012年   288篇
  2011年   303篇
  2010年   177篇
  2009年   185篇
  2008年   330篇
  2007年   325篇
  2006年   345篇
  2005年   354篇
  2004年   304篇
  2003年   321篇
  2002年   269篇
  2001年   256篇
  2000年   279篇
  1999年   269篇
  1998年   80篇
  1997年   43篇
  1996年   52篇
  1995年   50篇
  1994年   40篇
  1993年   37篇
  1992年   175篇
  1991年   143篇
  1990年   137篇
  1989年   139篇
  1988年   124篇
  1987年   123篇
  1986年   125篇
  1985年   112篇
  1984年   80篇
  1983年   55篇
  1981年   26篇
  1979年   51篇
  1977年   42篇
  1975年   24篇
  1974年   26篇
  1971年   37篇
  1969年   29篇
  1968年   28篇
  1967年   24篇
  1966年   23篇
排序方式: 共有6999条查询结果,搜索用时 31 毫秒
1.
The association between kidney function and cancer incidence is inconsistent among previous reports, and data on the Japanese population are lacking. It is unknown whether kidney function modifies the cancer risk of other factors. We aimed to evaluate the association of estimated glomerular filtration rate (eGFR) with cancer incidence and mortality in 55 242 participants (median age, 57 years; 55% women) from the Japan Multi-Institutional Collaborative Cohort Study. We also investigated differences in cancer risk factors between individuals with and without kidney dysfunction. During a median 9.3-year follow-up period, 4278 (7.7%) subjects developed cancer. Moderately low and high eGFRs were associated with higher cancer incidence; compared with eGFR of 60-74 ml/min/1.73 m2, the adjusted hazard ratios (HRs) (95% confidence intervals [CIs]) for eGFRs of ≥90, 75-89, 45-59, 30-44 and 10-29 ml/min/1.73 m2 were 1.18 (1.07-1.29), 1.09 (1.01-1.17), 0.93 (0.83-1.04), 1.36 (1.00-1.84) and 1.12 (0.55-2.26), respectively. High eGFR was associated with higher cancer mortality, while low eGFR was not; the adjusted subdistribution HRs (95% CIs) for eGFRs of ≥90 and 75-89 ml/min/1.73 m2 were 1.58 (1.29-1.94) and 1.27 (1.08-1.50), respectively. Subgroup analyses of participants with eGFRs ≥60 and <60 ml/min/1.73 m2 revealed elevated cancer risks of smoking and family history of cancer in those with eGFR <60 ml/min/1.73 m2, with significant interactions. Our findings suggest that the relationship between eGFR and cancer incidence was U-shaped. Only high eGFR was associated with cancer mortality. Kidney dysfunction enhanced cancer risk from smoking.  相似文献   
2.
ABSTRACT

Household effluents are predominantly treated by wastewater treatment plants (WWTPs). Other treatment methods, which were examined in this study, are also used in the countryside. These treatment modes include (1) onsite toilet wastewater treatment system (OTWTS), (2) onsite wastewater treatment system (OWTS), (3) community wastewater treatment system (CWTS), and (4) onsite vault toilet (OVT). Household effluents consist of excrements and urine released from toilets as well as wastewater released from kitchens and bathrooms. In the present study, household effluents that were discharged from the residential areas having undergone similar treatment methodologies were compared using the umu test, an in vitro bioassay to assess genotoxicity potential. The different treatment methodologies were categorized based upon whether the two kinds of wastewater were mixed or not mixed and treated or not treated. Treated wastewater containing excrements and urine from the OTWTS exhibited the strongest genotoxicity potential compared to other effluents, whereas most of the kitchen and bathroom wastewater from OVT did not display genotoxicity. Data indicated that the genotoxicants in the effluents originated primarily from excrements and urine, and may increase an adverse environmental risk.  相似文献   
3.
Upon infection or brain damage, microglia are activated to play roles in immune responses, including phagocytosis and soluble factor release. However, little is known whether the event of phagocytosis could be a trigger for releasing soluble factors from microglia. In this study, we tested if microglia secrete a neurovascular mediator matrix metalloproteinase-9 (MMP-9) after phagocytosis in vitro. Primary microglial cultures were prepared from neonatal rat brains. Cultured microglia phagocytosed Escherichia coli bioparticles within 2 hr after incubation and started to secrete MMP-9 at around 12 hr after the phagocytosis. A TLR4 inhibitor TAK242 suppressed the E. coli-bioparticle-induced MMP-9 secretion. However, TAK242 did not change the engulfment of E. coli bioparticles in microglial cultures. Because lipopolysaccharides (LPS), the major component of the outer membrane of E. coli, also induced MMP-9 secretion in a dose–response manner and because the response was inhibited by TAK242 treatment, we assumed that the LPS-TLR4 pathway, which was activated by adhering to the substance, but not through the engulfing process of phagocytosis, would play a role in releasing MMP-9 from microglia after E. coli bioparticle treatment. To support the finding that the engulfing step would not be a critical trigger for MMP-9 secretion after the event of phagocytosis in microglia, we confirmed that cell debris and amyloid beta were both captured into microglia via phagocytosis, but neither of them induced MMP-9 secretion from microglia. Taken together, these data demonstrate that microglial response in MMP-9 secretion after phagocytosis differs depending on the types of particles/substances that microglia encountered.  相似文献   
4.
5.
6.
7.

Background

There were few studies assessed the postoperative sarcopenia in patients with cancers. The objective of present study was to assess whether postoperative development of sarcopenia could predict a poor prognosis in patients with adenocarcinoma of esophagogastric junction, (AEG) and upper gastric cancer (UGC).

Methods

Patients with AEG and UGC who were judged as non-sarcopenic before surgery were reassessed the presence of postoperative development of sarcopenia 6 months after surgery. Patients were divided into the development group or non-development group, and clinicopathological factors and prognosis between these two groups were analyzed.

Results

The 5-year overall survival rates were significantly poorer in the development group than non-development group (68.0% vs. 92.6%, P?=?0.0118). Multivariate analyses showed that postoperative development of sarcopenia was an independent prognostic factor for poor overall survival (P?=?0.0237).

Conclusions

Postoperative development of sarcopenia was associated with a poor prognosis in patients with AEG and UGC.  相似文献   
8.
[Purpose] This study aimed to clarify the required number of measurements to calculate trunk muscle thickness at each position. [Participants and Methods] The participants were 30 elderly males aged >65 years. The right lumbar multifidus (L2), lumbar multifidus (L5), erector spinae, transversus abdominis, internal oblique, and external oblique muscle thicknesses were measured on longitudinal images obtained using ultrasonography in the lying, sitting, and standing positions. Two measurement values for each muscle thickness was used to calculate the intraclass correlation coefficient (1.1–1.5). [Results] The intraclass correlation coefficients of the abdominal muscle thickness measurements with “great reliabilities” were as follows: 1.3–1.5 for the external oblique muscle and 1.2–1.5 for the internal oblique and transversus abdominis muscles in the lying position; 1.3–1.5 for the external oblique and transversus abdominis muscles and 1.2–1.5 for the internal oblique muscle in the sitting position; the intraclass correlation coefficient in the standing position was 1.5 for the external oblique muscle 1.1–1.5 for the internal oblique muscle and 1.3–1.5 for the transversus abdominis muscle. In all the positions, the intraclass correlation coefficient of the measurements of the back-muscle thicknesses ranged from 1.1 to 1.5 for the right lumbar multifidus (L2), lumbar multifidus (L5), and erector spinae. [Conclusion] Depending on the posture, the abdominal muscles require multiple measurements, whereas the back muscles only require a single measurement.Key words: Intraclass correlation coefficient, Trunk muscle thicknesses, Ultrasonography  相似文献   
9.

Purpose

To investigate the blood-to-retina verapamil transport at the blood-retinal barrier (BRB).

Methods

EverFluor FL Verapamil (EFV) was adopted as the fluorescent probe of verapamil, and its transport across the BRB was investigated with common carotid artery infusion in rats. EFV transport at the inner and outer BRB was investigated with TR-iBRB2 cells and RPE-J cells, respectively.

Results

The signal of EFV was detected in the retinal tissue during the weak signal of cell impermeable compound. In TR-iBRB2 cells, the localization of EFV differed from that of LysoTracker® Red, a lysosomotropic agent, and was not altered by acute treatment with NH4Cl. In RPE-J cells, the punctate distribution of EFV was partially observed, and this was reduced by acute treatment with NH4Cl. EFV uptake by TR-iBRB2 cells was temperature-dependent and membrane potential- and pH-independent, and was significantly reduced by NH4Cl treatment during no significant effect obtained by different extracellular pH and V-ATPase inhibitor. The EFV uptake by TR-iBRB2 cells was inhibited by cationic drugs, and inhibited by verapamil in a concentration-dependent manner with an IC50 of 98.0 μM.

Conclusions

Our findings provide visual evidence to support the significance of carrier-mediated transport in the blood-to-retina verapamil transport at the BRB.
  相似文献   
10.
Spontaneous regeneration of lesioned fibers is limited in the adult central nervous system due to an unfavorable environment. Several myelin-derived proteins have been identified to inhibit neurite outgrowth in vitro. These proteins induce activation of Rho in some neurons. Inhibition of Rho or Rho-kinase, downstream effector of Rho, promotes axon regeneration in vivo. Recent reports suggest that several other proteins are axon growth inhibitors. Therapeutic strategy to block the multiple axon growth inhibitors may provide efficient tools that produce functional regeneration following injuries to the central nervous system. In addition, it is noted that synaptic plasticity in pre-existing pathways and the formation of new circuits through collateral sprouting of lesioned and unlesioned fibers are important components of the recovery process.  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