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   176708篇
  免费   1127篇
  国内免费   6篇
耳鼻咽喉   1135篇
儿科学   6714篇
妇产科学   3083篇
基础医学   16727篇
口腔科学   1544篇
临床医学   12524篇
内科学   30968篇
皮肤病学   699篇
神经病学   16617篇
特种医学   8936篇
外科学   28866篇
综合类   2333篇
一般理论   6篇
预防医学   18378篇
眼科学   2736篇
药学   9527篇
中国医学   625篇
肿瘤学   16423篇
  2023年   35篇
  2022年   52篇
  2021年   96篇
  2020年   50篇
  2019年   92篇
  2018年   21986篇
  2017年   17420篇
  2016年   19545篇
  2015年   955篇
  2014年   856篇
  2013年   865篇
  2012年   7072篇
  2011年   21080篇
  2010年   18860篇
  2009年   11549篇
  2008年   19542篇
  2007年   21757篇
  2006年   590篇
  2005年   2216篇
  2004年   3398篇
  2003年   4367篇
  2002年   2524篇
  2001年   283篇
  2000年   420篇
  1999年   177篇
  1998年   231篇
  1997年   223篇
  1996年   104篇
  1995年   124篇
  1994年   106篇
  1993年   62篇
  1992年   49篇
  1991年   93篇
  1990年   129篇
  1989年   83篇
  1988年   57篇
  1987年   43篇
  1986年   29篇
  1985年   35篇
  1983年   24篇
  1982年   32篇
  1980年   46篇
  1974年   21篇
  1970年   23篇
  1938年   66篇
  1937年   26篇
  1935年   28篇
  1934年   32篇
  1932年   56篇
  1930年   47篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Adolescence is a tumultuous and challenging time period in life. Sexual risk behavior among adolescents is a widespread topic of interest in the current literature. Two common factors that influence increased sexual risk behavior are symptoms of depression and negative body image. The purpose of this study was to investigate the effect of body image and symptoms of depression upon sexual risk-taking in an adolescent female population. A secondary data analysis of the 2011 Youth Risk Behavior Survey (YRBS) was used to explore girls’ sexual activity, body image, and mental health. There were 7,708 high-school girls who participated in this study. Three questions were used to represent the constructs under investigation. There were significant correlations between sexual activity, body image, and symptoms of depression; only symptoms of depression were significant predictors of both sexual activity and condom usage. Body image was a predictor of sexual activity, but not condom use. Our findings support previous studies that suggested that people with depressive symptoms were more likely to engage in risky sexual behaviors. Our study also supports the idea that a negative body image decreases sexual activity; however, other researchers have reported that negative body image leads to an increase in sexual activity.  相似文献   
2.
Magnetic field generated by neuronal activity could alter magnetic resonance imaging (MRI) signals but detection of such signal is under debate. Previous researches proposed that magnitude signal change is below current detectable level, but phase signal change (PSC) may be measurable with current MRI systems. Optimal imaging parameters like echo time, voxel size and external field direction, could increase the probability of detection of this small signal change. We simulate a voxel of cortical column to determine effect of such parameters on PSC signal. We extended a laminar network model for somatosensory cortex to find neuronal current in each segment of pyramidal neurons (PN). 60,000 PNs of simulated network were positioned randomly in a voxel. Biot–savart law applied to calculate neuronal magnetic field and additional phase. The procedure repeated for eleven neuronal arrangements in the voxel. PSC signal variation with the echo time and voxel size was assessed. The simulated results show that PSC signal increases with echo time, especially 100/80 ms after stimulus for gradient echo/spin echo sequence. It can be up to 0.1 mrad for echo time = 175 ms and voxel size = 1.48 × 1.48 × 2.18 mm3. With echo time less than 25 ms after stimulus, it was just acquired effects of physiological noise on PSC signal. The absolute value of the signal increased with decrease of voxel size, but its components had complex variation. External field orthogonal to local surface of cortex maximizes the signal. Expected PSC signal for tactile detection in the somatosensory cortex increase with echo time and have no oscillation.  相似文献   
3.
4.
5.
Farnesyltransferase (FTase) is one of the prenyltransferase family enzymes that catalyse the transfer of 15-membered isoprenoid (farnesyl) moiety to the cysteine of CAAX motif-containing proteins including Rho and Ras family of G proteins. Inhibitors of FTase act as drugs for cancer, malaria, progeria and other diseases. In the present investigation, we have developed two structure-based pharmacophore models from protein–ligand complex (3E33 and 3E37) obtained from the protein data bank. Molecular dynamics (MD) simulations were performed on the complexes, and different conformers of the same complex were generated. These conformers were undergone protein–ligand interaction fingerprint (PLIF) analysis, and the fingerprint bits have been used for structure-based pharmacophore model development. The PLIF results showed that Lys164, Tyr166, TrpB106 and TyrB361 are the major interacting residues in both the complexes. The RMSD and RMSF analyses on the MD-simulated systems showed that the absence of FPP in the complex 3E37 has significant effect in the conformational changes of the ligands. During this conformational change, some interactions between the protein and the ligands are lost, but regained after some simulations (after 2 ns). The structure-based pharmacophore models showed that the hydrophobic and acceptor contours are predominantly present in the models. The pharmacophore models were validated using reference compounds, which significantly identified as HITs with smaller RMSD values. The developed structure-based pharmacophore models are significant, and the methodology used in this study is novel from the existing methods (the original X-ray crystallographic coordination of the ligands is used for the model building). In our study, along with the original coordination of the ligand, different conformers of the same complex (protein–ligand) are used. It concluded that the developed methodology is significant for the virtual screening of novel molecules on different targets.  相似文献   
6.
This paper takes a somewhat slant perspective on flourishing and care in the context of suffering, death and dying, arguing that care in this context consists principally of ‘acts of work and courage that enable flourishing’. Starting with the perception that individuals, society and health care professionals have become dulled to death and the process of dying in Western advanced health systems, it suggests that for flourishing to occur, both of these aspects of life need to be faced more directly. The last days of life need to be ‘undulled’. Reflections upon the experiences of the author as carer and daughter in the face of her mother’s experience of death are used as basis for making suggestions about how care systems and professionals might better assist people in dealing with ‘the most grown up thing’ humans ever do, which is to die.  相似文献   
7.
8.
Advancing nanomedicines from concept to clinic requires integration of new science with traditional pharmaceutical development. The medical and commercial success of nanomedicines is greatly facilitated when those charged with developing nanomedicines are cognizant of the unique opportunities and technical challenges that these products present. These individuals must also be knowledgeable about the processes of clinical and product development, including regulatory considerations, to maximize the odds for successful product registration. This article outlines these topics with a goal to accelerate the combination of academic innovation with collaborative industrial scientists who understand pharmaceutical development and regulatory approval requirements—only together can they realize the full potential of nanomedicines for patients.  相似文献   
9.
10.
While peer support has been investigated in multiple clinical contexts, its application to the postpartum setting is unknown. The aim was to assess acceptability of a postpartum peer support program for women with diabetes. Observational survey-based needs assessment of forty low-income women with diabetes, receiving care at a major medical institution. Mean age and gravidity were 30.7 years and 3.15 ± 1.67 respectively. 45 % expressed interest in a “buddy.” There was no significant difference between groups desiring and not desiring this program. A majority of respondents desired telephone, text messaging, and in-person contacts (79.2, 72.1, 83.8 %), with 72.5 % of patients desiring diabetes-related activities during clinic waiting time. Many women desire a postpartum diabetes reciprocal peer program for support outside of clinician visits. Patients are receptive to educational services during their wait and outside of clinic time, a potentially valuable opportunity to share important health information.  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