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   5712篇
  免费   533篇
  国内免费   9篇
耳鼻咽喉   72篇
儿科学   195篇
妇产科学   162篇
基础医学   810篇
口腔科学   57篇
临床医学   755篇
内科学   988篇
皮肤病学   109篇
神经病学   644篇
特种医学   111篇
外科学   563篇
综合类   48篇
一般理论   6篇
预防医学   702篇
眼科学   324篇
药学   334篇
中国医学   3篇
肿瘤学   371篇
  2024年   16篇
  2023年   127篇
  2022年   164篇
  2021年   425篇
  2020年   268篇
  2019年   337篇
  2018年   333篇
  2017年   273篇
  2016年   289篇
  2015年   236篇
  2014年   320篇
  2013年   363篇
  2012年   465篇
  2011年   487篇
  2010年   234篇
  2009年   209篇
  2008年   296篇
  2007年   247篇
  2006年   226篇
  2005年   214篇
  2004年   165篇
  2003年   190篇
  2002年   158篇
  2001年   24篇
  2000年   10篇
  1999年   11篇
  1998年   33篇
  1997年   12篇
  1996年   12篇
  1995年   7篇
  1994年   7篇
  1993年   5篇
  1992年   4篇
  1991年   6篇
  1990年   7篇
  1989年   7篇
  1987年   7篇
  1986年   3篇
  1985年   6篇
  1984年   3篇
  1983年   5篇
  1982年   3篇
  1980年   4篇
  1979年   3篇
  1975年   2篇
  1973年   7篇
  1972年   4篇
  1970年   3篇
  1969年   2篇
  1967年   2篇
排序方式: 共有6254条查询结果,搜索用时 140 毫秒
41.
The purpose of this study was to characterize presenting imaging findings in women younger than 40 diagnosed with invasive breast cancer in the context of pathology and clinical course. Retrospective chart and imaging reviews were performed in patients under 40 diagnosed with breast cancer between July 1, 2004, and December 31, 2013. Patient demographic, imaging, pathology, and clinical data were collected. Overall and recurrence-free survival were estimated using the Kaplan-Meier method. Univariate Cox proportional hazards models were performed to identify factors associated with recurrence-free survival. Our study cohort consisted of 110 patients with invasive mammary carcinoma. One hundred one (91.8%) presented with a palpable mass. The mean size of all lesions on imaging was 3.5 cm ± 2.9 cm. Malignant calcifications were present in 54 (49.1%) cases. Imaging demonstrated multifocal or multicentric disease in 45 (40.9%) cases. Seventy four (67.3%) cancers were high grade. Luminal genomic subtypes were the most common (n = 61, 55.5%). At presentation, 4 (3.6%) patients had bilateral malignancy and 8 (7.3%) patients had distant metastatic disease. Ninety seven (88.2%) underwent neoadjuvant chemotherapy and 67 (60.9%) underwent radiation therapy. Seventy five (68.2%) of the patients underwent mastectomy. The restricted mean time to recurrence was 9.01 years (standard error 3.162 months). ER positivity was associated with compromised recurrence-free survival. The overall survival rate was 0.962 at 10 years. Young patients diagnosed with breast cancer typically present with advanced breast imaging findings and undergo aggressive treatment. Recurrence often occurs >5 years from diagnosis, and ER positive subtypes are at increased risk for recurrence.  相似文献   
42.
43.
BackgroundWe tested if disrupting iron utilisation by P. aeruginosa by adding the Tris-buffered chelating agent CaEDTA to nebulised tobramycin would enhance bacterial clearance and improve lung function in CF patients.MethodsIn this double-blind, randomised controlled trial, 26 episodes (25 patients) with P. aeruginosa infection admitted to two CF centres for treatment of an acute pulmonary exacerbation were randomly assigned to receive either 75 mg CaEDTA in Tris-buffered saline or placebo (Tris-buffered saline) nebulised in combination with 250 mg tobramycin twice daily for six weeks followed with four week safety follow-up. Primary endpoints were safety, tolerability, and bacterial density of P. aeruginosa. A secondary endpoint was lung function.ResultsThe study drug was well tolerated with adverse events comparable in both groups. The mean (SD) reduction in sputum P. aeruginosa count (log10 CFU/g) in the CaEDTA vs placebo group was 2·05 (2·57) vs 0·82 (2·71) at two weeks relative to admission (p = 0·39). The mean improvement in ppFEV1 was 16 vs 5 (p = 0·16); 11 vs 2 (p = 0·28); and 6 vs 2 percentage points (p = 0·47) at two, six, and ten weeks in CaEDTA and placebo groups, respectively.ConclusionsIn this pilot study in CF patients, an increase in the reduction of sputum density of P. aeruginosa and an increase in ppFEV1 was observed in the group of patients who received Tris-CaEDTA added to inhaled tobramycin compared to the group who received inhaled tobramycin alone, although these differences were not statistically significant. The treatment was also shown to be safe.  相似文献   
44.

Research conducted in our laboratory and in other laboratories has revealed that (1) women’s genital responses to visual and auditory stimuli are strongly affected by the presence of sexual cues, but that (2) specific sexual cues (e.g., gender of actors, the presence of sexual violence) often have little impact on the magnitude of the responses—that is, similar genital responses are observed to very different sexual stimuli. In addition, (3) women’s genital responses do not strongly correspond with self-reported sexual partner and activity preferences, or (4) with self-reported sexual arousal during the presentation of sexual stimuli. Taken together, these facts represent a puzzle, especially considering that men’s genital responses are highly affected by specific sexual cues and strongly correspond to stated preferences and self-reported sexual arousal. One hypothesis to explain female low cue-specificity and low concordance (relative to men) is the preparation hypothesis: Women’s indiscriminate genital responses serve a protective function. That is, they do not indicate or necessarily promote sexual interest and motivation, but rather prepare the vaginal lumen for possible sexual activity and therefore prevent injuries that may occur as a result of penetration. We review evidence for and against this hypothesis. We conclude that the evidence is favorable but not entirely convincing, and more work is required to reach a firm conclusion. We offer directions for future research.

  相似文献   
45.
Archives of Sexual Behavior - Research on asexuality as a part of the experience of human sexuality has increased over the last two decades. However, there has not yet been a systematic review of...  相似文献   
46.

The COVID-19 pandemic and the mitigation measures put in place have resulted in universal disruption in the usual ways of life for individuals. The current study sought to investigate how aspects of sexual health (well-being and functioning) and relationship satisfaction changed or remained stable during the pandemic. During two separate time points (Time 1 including Time 1 and a retrospective baseline, Time 2), participants completed online measures of sexual well-being (sexual pleasure, partnered and solitary orgasm frequency, sexual distress), sexual functioning, and relationship satisfaction. Participants reported slight declines in sexual pleasure, frequency of orgasms with a partner, and frequency of solitary orgasms from pre-COVID-19 (retrospective baseline) to Time 1, with no significant differences in sexual distress and relationship satisfaction. For individuals with vulvas, sexual functioning improved from Time 1 to Time 2, whereas no significant differences in sexual functioning were observed for individuals with penises. Aspects of sexual health and relational satisfaction did not sufficiently change across time points to be considered meaningful health outcome changes. Given that minimal disruptions were noted in pre-COVID-19 to COVID-19 sexuality, these results highlight the potential resiliency of individuals’ sexuality when facing sudden changes in their daily lives. Implications of COVID-19’s effects on sexual well-being and relationship satisfaction research are broadly discussed.

  相似文献   
47.
Journal of Community Health - Tattoos of formerly gang-involved and incarcerated individuals can negatively impact their ability to reintegrate into society. Laser tattoo removal is essential to...  相似文献   
48.
The Magnaporthe grisea ERG2 gene, encoding 87 sterol isomerase, was isolated from a genomic library by heterologous hybridization to a fragment of the Ustilago maydis ERG2 gene. The isolated gene contained a reading frame of 745 bp which encoded a protein of 221 amino acids. The coding region was interrupted by a single putative 79-bp-long intron. The deduced amino-acid sequence exhibited similarity to the ERG2 gene products of U. maydis and of Saccharomyces cerevisiae, particularly in the central region of the proteins. The NH2-terminal of all three proteins contained a long stretch of amino acids that were strongly hydrophobic, suggesting that they may function by anchoring the protein to a membrane surface. The M. grisea ERG2 gene complemented a U. maydis deletion mutant in which the ERG2 gene had been removed using a one-step gene replacement procedure. The 87 sterol isomerase produced by the M. grisea ERG2 gene exhibited a level of sensitivity to the sterol biosynthesis inhibitor, tridemorph, similar to that of the enzyme derived from the U. maydis ERG2 gene.  相似文献   
49.
An analysis of variability in the stereotaxic position of five cerebral points in rats revealed:
1. (1) that variability was less from the bregma skull point than from ear-bar-zero or the lambda skull point,
2. (2) that high correlations exist between the position of skull points and cerebral structures, and
3. (3) that the use of two external landmarks for predicting the position of cerebral targets produces a greater than 40% reduction in errors over that resulting from the use of single (ear-bar-zero or skull landmark) predictors.
Keywords: Stereotaxic variability; Electrode placement; Rat  相似文献   
50.
Systemic vasodilatation in surfactant-depleted newborn piglets is induced by 200 mg/kg of modified porcine lung surfactant (Curosurf™). The aim of this investigation was to study whether this effect is dependent on dose and could further be induced by instillation of a bovine surfactant preparation (Survanta™). Twenty-two 3–5-d old piglets were subjected to repeated saline lung lavage and then randomized to one of three groups. Instillation of either Curosurf 100 mg/kg ( n = 8), Survanta 100 mg/kg ( n = 7) or Curosurf 200 mg/kg ( n = 7) was performed through the endotracheal tube. Systemic vascular resistance decreased 7 (± 4)%, 15 (± 12)% and 18 (± 6)% in the three groups, respectively ( p < 0:05 in all three groups). A significant difference between the high and low dose Curosurf groups was found ( p < 0:05), whereas no significant difference was seen between the Curosurf 100 mg group and the Survanta group. The decrease in vascular resistance was compensated by an increase in cardiac output, resulting in a stable mean arterial blood pressure. In conclusion, both Curosurf and Survanta induce a significant decrease in systemic vascular resistance in surfactant-depleted newborn piglets. A more pronounced effect was observed after 200 mg/kg than after 100 mg/kg of Curosurf.  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