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   7795篇
  免费   614篇
  国内免费   27篇
耳鼻咽喉   114篇
儿科学   263篇
妇产科学   275篇
基础医学   1100篇
口腔科学   117篇
临床医学   947篇
内科学   1404篇
皮肤病学   137篇
神经病学   752篇
特种医学   197篇
外科学   785篇
综合类   58篇
一般理论   10篇
预防医学   881篇
眼科学   162篇
药学   497篇
中国医学   33篇
肿瘤学   704篇
  2023年   57篇
  2022年   93篇
  2021年   207篇
  2020年   163篇
  2019年   196篇
  2018年   189篇
  2017年   149篇
  2016年   195篇
  2015年   191篇
  2014年   304篇
  2013年   383篇
  2012年   604篇
  2011年   585篇
  2010年   339篇
  2009年   330篇
  2008年   528篇
  2007年   511篇
  2006年   495篇
  2005年   460篇
  2004年   477篇
  2003年   463篇
  2002年   408篇
  2001年   78篇
  2000年   54篇
  1999年   68篇
  1998年   90篇
  1997年   77篇
  1996年   54篇
  1995年   61篇
  1994年   58篇
  1993年   54篇
  1992年   40篇
  1991年   36篇
  1990年   34篇
  1989年   28篇
  1988年   20篇
  1987年   19篇
  1986年   16篇
  1985年   26篇
  1984年   29篇
  1983年   18篇
  1982年   24篇
  1981年   22篇
  1978年   15篇
  1977年   12篇
  1975年   14篇
  1973年   18篇
  1972年   19篇
  1971年   11篇
  1970年   11篇
排序方式: 共有8436条查询结果,搜索用时 0 毫秒
71.

Because the public health response to the disproportionate HIV burden faced by Black sexual minority men (BSMMM) has focused on sexual risk reduction and disease prevention, other vital components of sexual health (e.g., intimacy, pleasure, benefits of sex) have been often overlooked. Sex-positive describes a more open, holistic approach toward sex and sexuality that prioritizes these other components, though such an approach is rarely applied to BSMM's sexual health. For sex-positive BSMM, risk/preventive discourse may foster or exacerbate medical mistrust as a reaction to the dissonance between how these men view sexual health and how the medical establishment views it, which may discourage sexual healthcare-seeking. We assessed sex-positivity and its association with medical mistrust and PrEP conspiracy beliefs among 206 HIV-negative cisgender BSMM in Atlanta, Georgia. We performed exploratory factor analytic procedures on responses to a sex-positivity scale, followed by multivariable linear regressions to determine sex-positivity’s associations with medical mistrust and PrEP conspiracy beliefs. We extracted two sex-positivity factors: sexual freedom (α?=?0.90), reflecting openness toward casual sex and rejection of sexual mores, and essence of sex (α?=?0.77), reflecting the intimate, relational, and pleasurable qualities of sex. Sexual freedom was independently associated with perceived provider deception (β?=?0.19, CI?=?0.04, 0.34). Essence of sex was independently associated with PrEP conspiracy beliefs (β?=?0.16, CI?=?0.02, 0.31) and marginally associated with perceived provider deception (β?=?0.14, CI?=???0.00, 0.29). Healthcare providers and public health practitioners may cultivate greater trust with BSMM by incorporating a sex-positive approach into patient/participant interactions, clinical decision-making, and interventions. Improving access to sexual pleasure acknowledges BSMM’s right to optimal, holistic sexual health.

  相似文献   
72.
Archives of Sexual Behavior - The present study presents a typology of identity gaps (Hecht, 1993), or cognitive, affective, and behavioral discrepancies between and among different parts of the...  相似文献   
73.
ObjectivesTo understand the differential vulnerability to household food insecurity of the Black population as compared with white counterparts in Canada.MethodsUsing data for households with Black and white respondents in pooled Canadian Community Health Survey cycles from 2005 to 2014, the 18-question Household Food Security Survey Module was analyzed (N = 491,400). Bivariate and multivariate logistic and multinomial regression models were run using respondent’s race, immigration status, and six well-established predictors of household food insecurity in the general population. Additional multivariable logistic regression models were run, with race interacted with each predictor individually to yield predicted probabilities.ResultsThe weighted prevalence of household food insecurity was 10.0% for white respondents and 28.4% for Black respondents. The odds of Black households being food-insecure as compared with white households fell from 3.56 (95% CI: 3.30–3.85) to 1.88 (95% CI: 1.70–2.08) with adjustment for household socio-demographic characteristics. In contrast with white households, there was relative homogeneity of risk of food insecurity among Black subgroups defined by immigration status, household composition, education, and province of residence. Homeownership was associated with lower probabilities of food insecurity for Black and white households, but the probability among Black owners was similar to that for white renters (14.7% vs. 14.3%). Black households had significantly higher predicted probabilities of food insecurity than their white counterparts across all main sources of household income except child benefits and social assistance.ConclusionBeing racialized as Black appears to be an overriding factor shaping vulnerability to food insecurity for the Black population in Canada. Future research and public policy on food insecurity should seriously consider the role of racism at the systemic and institutional levels.  相似文献   
74.
75.
Alopecia is one of the common symptoms after high-dose radiation exposure. In our experiments, neonatal mice that received 7 Gy X-ray exhibited defects in overall hair growth, except for their cheeks. This phenomenon might suggest that some substances were secreted and prevented hair follicle loss in the infant tissues around their cheeks after radiation damage. In this study, we focused on exosome-like vesicles (ELV) secreted from cheek skin tissues and back skin tissues, as control, and examined their radiation protective effects on mouse fibroblast cell lines. We observed that ELV from irradiated cheek skin showed protective effects from radiation. Our results suggest that ELV from radiation-exposed cheek skin tissue is one of the secreted factors that prevent hair follicle loss after high-dose radiation.  相似文献   
76.
The accessibility of eukaryotic DNA is dependent upon the hierarchical level of chromatin organization. These include (1) intra-nucleosome interactions, (2) inter-nucleosome interactions and (3) the influence of non-histone chromatin architectural proteins. There appears to be interplay between all these levels, in that one level can override another or that two or more can act in concert. In the first level, the stability of the nucleosome itself is dependent on the number and type of contacts between the core histones and the surrounding DNA, as well as protein–protein interactions within the core histone octamer. Core histone variants, post-translational modifications of the histones, and linker histones binding to the DNA all influence the organization and stability of the nucleosome. When nucleosomes are placed end-to-end in linear chromatin arrays, the second level of organization is revealed. The amino terminal tails of the histone proteins make contacts with adjacent and distant nucleosomes, both within the fiber and between different fibers. The third level of organization is imposed upon these ‘intrinsic’ constraints, and is due to the influence of chromatin binding proteins that alter the architecture of the underlying fiber. These chromatin architectural proteins can, in some cases, bypass intrinsic constraints and impart their own topological affects, resulting in truly unique, supra-molecular assemblages that undoubtedly influence the accessibility of the underlying DNA. In this review we will provide a brief summary of what has been learned about the intrinsic dynamics of chromatin fibers, and survey the biology and architectural affects of the handful of chromatin architectural proteins that have been identified and characterized. These proteins are likely only a small subset of the architectural proteins encoded within the eukaryotic genome. We hope that an increased understanding and appreciation of the contribution of these proteins to genome accessibility will hasten the identification and characterization of more of these important regulatory factors.  相似文献   
77.
  1. Imidazoline α2-antagonist drugs such as efaroxan have been shown to increase the insulin secretory response to sulphonylureas from rat pancreatic B-cells. We have investigated whether this reflects binding to an islet imidazoline receptor or whether α2-adrenoceptor antagonism is involved.
  2. Administration of (±)-efaroxan or glibenclamide to Wistar rats was associated with a transient increase in plasma insulin. When both drugs were administered together, the resultant increase in insulin levels was much greater than that obtained with either drug alone.
  3. Use of the resolved enantiomers of efaroxan revealed that the ability of the compound to enhance the insulin secretory response to glibenclamide resided only in the α2-selective-(+)-enantiomer; the imidazoline receptor-selective-(−)-enantiomer was ineffective.
  4. In vitro, (+)-efaroxan increased the insulin secretory response to glibenclamide in rat freshly isolated and cultured islets of Langerhans, whereas (−)-efaroxan was inactive. By contrast, (+)-efaroxan did not potentiate glucose-induced insulin secretion but (−)-efaroxan induced a marked increase in insulin secretion from islets incubated in the presence of 6 mM glucose.
  5. Incubation of rat islets under conditions designed to minimize the extent of α2-adrenoceptor signalling (by receptor blockade with phenoxybenzamine; receptor down-regulation or treatment with pertussis toxin) abolished the capacity of (+)-and (±)-efaroxan to enhance the insulin secretory response to glibenclamide. However, these manoeuvres did not alter the ability of (±)-efaroxan to potentiate glucose-induced insulin secretion.
  6. The results indicate that the enantiomers of efaroxan exert differential effects on insulin secretion which may result from binding to effector sites having opposite stereoselectivity. Binding of (−)-efaroxan (presumably to imidazoline receptors) results in potentiation of glucose-induced insulin secretion, whereas interaction of (+)-efaroxan with a second site leads to selective enhancement of sulphonylurea-induced insulin release.
  相似文献   
78.
Since coronary heart disease (CHD) is the leading cause of death in American women it is therefore likely the leading cause of death among lesbians. Prevention of CHD is a major health issue for lesbians. Efforts must continue to empower all lesbians to take personal preventative action to prevent CHD. Women in general do not believe they are at risk for CHD. A common misperception is that CHD is a man's disease and the most likely threat to a woman's life is breast cancer. This misperception probably exists among lesbians as well. Over a lifetime, a woman is 10 times more likely to develop CHD than she is breast cancer. Breast cancer remains an important health concern for woman, but CHD risk must be addressed with potent educational and advocacy programs for the health of our communities. Prevention of the clinical manifestations of CHD hinges upon the prevention of plaque formation. It is an obligation of primary care providers to give advice regarding the prevention of plaque formation and therefore the prevention of subsequent CHD events and to collaborate with patients to address these issues in an individually tailored manner. This review addresses risk factors for CHD in lesbians to assist providers in achievement of that goal.  相似文献   
79.
Background. Prior studies of recall accuracy for screening mammogram behavior have examined relatively homogeneous groups. Data are limited on possible systematic group differences, so we evaluated women's recall accuracy in two separate care systems in one city.Methods. Women 50 to 70 years old with and without screening mammograms 10 to 14 months prior were identified from fiscal, clinic, and radiology records at a military care system (MCS) and a county-funded system (CFS) for indigents. Mammogram status was verified through radiology records. Women were excluded if mammograms were diagnostic, done for other than annual screening, or had abnormal results. Interview ers blinded to mammogram status surveyed randomly selected eligible women.Results. For 62 screened/31 unscreened MCS women and 78 screened/61 unscreened CFS women, specificity was similar, at 65 and 62%, respectively. In contrast, sensitivity varied significantly: 95% versus 79% (P = 0.011). Primary ethonocultural groups were Euro-American (MCS—60%) and Mexican American (CFS—85%). Although not different in specificity of recall (67% versus 61%), these major subgroups significantly differed in sensitivity (97% versus 80%, P = 0.017), proportion of true negatives due to never having a mammogram (35% versus 57%, P = 0.003), and proportion with ≥high school education (78% versus 19%, P < 0.00001).Conclusion. Systematic differences in recall validity may exist and compromise the accuracy of intergroup comparisons.  相似文献   
80.
Rationale: Facial expressions appear to be processed by at least partially separable neuro-cognitive systems. Given this functional specialisation of expression processing, it is plausible that these neurocognitive systems may also be dissociable pharmacologically. Objective: The present study therefore compared the effects of diazepam (15 mg) with placebo upon the ability to recognise emotional expressions. Methods: A double blind, independent group design was used to compare the effects of diazepam and matched placebo in32 healthy volunteers. Participants were presented morphed facial expression stimuli following a paradigm developed for use with patients with brain damage and asked to name one of the six basic emotions (sadness, happiness, anger, disgust, fear and surprise). Results: Diazepam selectively impaired subjects’ ability to recognise angry expressions but did not affect recognition of any other emotional expression. Conclusions: The findings are interpreted as providing further support for the suggestion that there are dissociable systems responsible for processing emotional expressions. It is suggested that these findings may have implications for understanding paradoxical aggression sometimes elicited by benzodiazepines. Received: 27 May 1999 / Accepted: 7 July 1999  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