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   2140篇
  免费   208篇
  国内免费   7篇
耳鼻咽喉   45篇
儿科学   60篇
妇产科学   27篇
基础医学   333篇
口腔科学   24篇
临床医学   173篇
内科学   531篇
皮肤病学   59篇
神经病学   213篇
特种医学   75篇
外科学   286篇
综合类   3篇
预防医学   120篇
眼科学   62篇
药学   132篇
中国医学   3篇
肿瘤学   209篇
  2024年   2篇
  2023年   30篇
  2022年   32篇
  2021年   79篇
  2020年   52篇
  2019年   113篇
  2018年   121篇
  2017年   65篇
  2016年   78篇
  2015年   90篇
  2014年   106篇
  2013年   127篇
  2012年   215篇
  2011年   190篇
  2010年   124篇
  2009年   81篇
  2008年   149篇
  2007年   147篇
  2006年   101篇
  2005年   99篇
  2004年   76篇
  2003年   75篇
  2002年   67篇
  2001年   7篇
  2000年   8篇
  1999年   7篇
  1998年   11篇
  1997年   13篇
  1996年   5篇
  1995年   6篇
  1994年   6篇
  1993年   4篇
  1992年   8篇
  1991年   6篇
  1990年   5篇
  1988年   7篇
  1987年   6篇
  1986年   4篇
  1984年   5篇
  1983年   6篇
  1981年   2篇
  1979年   2篇
  1976年   2篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
  1970年   1篇
  1968年   1篇
  1967年   2篇
  1966年   3篇
排序方式: 共有2355条查询结果,搜索用时 15 毫秒
991.
In this paper we scanned and summarized the empirical research evidence and found that the effects of pre-licensure interprofessional education on patient/client care are unknown. In contrast, for post-licensure collaboration interventions, there is a growing body of evidence suggesting positive effects on the delivery of care. The coverage of this latter evidence, however, is patchy, being especially weak in primary care. In interprofessional education, where policy level interventions have been value driven for the last half century, we have identified a base of evidence for the effectiveness of certain post-licensure collaboration interventions; this evidence is lacking for pre-licensure interprofessional education. If interventions and policies for both pre-licensure interprofessional education and post-licensure collaboration are implemented without accompanying rigorous evaluation research, we will remain mired in this same uncertainty into the future.  相似文献   
992.
Recently, receptor protein tyrosine phosphatase-sigma (RPTPsigma) has been shown to inhibit axon regeneration in injured peripheral nerves. Unlike the peripheral nervous system (PNS), central nervous system (CNS) neurons fail to regenerate their axons after injury or in disease. In order to assess the role of RPTPsigma in CNS regeneration, we used the retinocollicular system of adult mice lacking RPTPsigma to evaluate retinal ganglion cell (RGC) axon regrowth after optic nerve lesion. Quantitative analysis demonstrated a significant increase in the number of RGC axons that crossed the glial scar and extended distally in optic nerves from RPTPsigma (-/-) mice compared to wild-type littermate controls. Although we found that RPTPsigma is expressed by adult RGCs in wild-type mice, the retinas and optic nerves of adult RPTPsigma (-/-) mice showed no histological defects. Furthermore, the time-course of RGC death after nerve lesion was not different between knockout and wild-type animals. Thus, enhanced axon regrowth in the absence of RPTPsigma could not be attributed to developmental defects or increased neuronal survival. Finally, we show constitutively elevated activity of mitogen-activated protein kinase (MAPK) and Akt kinase in adult RPTPsigma (-/-) mice retinas, suggesting that these signaling pathways may contribute to promoting RGC axon regrowth following traumatic nerve injury. Our results support a model in which RPTPsigma inhibits axon regeneration in the adult injured CNS.  相似文献   
993.
We describe a new type of caliper to optimize the size, shape, and centration of the capsulorhexis during intraocular lens (IOL) surgery. This flexible, ring-shaped tool is positioned on the anterior capsule surface, where it is kept in place by an ophthalmic viscosurgical device. When in place, the caliper provides an ideal guide for the surgeon to follow and facilitates optimal capsulorhexis shape and centration.  相似文献   
994.
Bridelia scleroneura is a member of the Euphorbiaceae family. In folk medicine in Cameroon, the stem bark of this plant is used for relieving abdominal pain, contortion, arthritis and inflammation. In this study, the antinociceptive and anti-inflammatory activities of the ethyl acetate stem bark extract have been evaluated. The putative analgesic effect of the plant extract was examined in abdominal constriction, hot plate, formalin and on pain using tail immersion mouse models and in carrageenan-induced paw edema in rats. The extract (150–600 mg/kg) exhibited a dose-dependent analgesic effect (46.27–78.97%) in acetic acid-induced abdominal constriction in mice. B. scleroneura extract increased the pain latency of nociceptive response to thermal stimuli at the higher dose of 600 mg/kg. B. scleroneuna induced significant dose-dependent reduction of the nociception in both early and late phases of the formalin test. The extract at the dose of 300 mg/kg, increased significantly, by 63.70% and 52.01% the tail-immersion latency time, 1 and 2 h post-dosing. In the carrageenan test, B. scleroneura (150–600 mg/kg, p.o) had dose-dependent and significant effects at different time intervals. This behaviour was similar to indometacin (10 mg/kg) used as a standard drug. These results show that the ethyl acetate stem bark extract of B. scleroneura possesses peripheral and central analgesic properties as well as anti-inflammatory activity against acute inflammation processes, in support of the folk medicinal use of the plant.  相似文献   
995.
The cellular immune response to hepatitis C virus (HCV) plays a critical role in determining the clearance or persistence of HCV. Moreover, in chronic HCV infection, these responses that are insufficient to eradicate virus completely may cause liver injury. In this study, the memory T cells responses specific to the core protein were measured by interferon-gamma Elispot assay after in vitro stimulation of peripheral blood mononuclear lymphocytes from chronically infected subjects. Ten out of the 22 patients studied (45%) present a core-specific response with a preferential recognition of the N-terminal and central parts. There was no relationship between T cell responses and the parameters of disease evolution as determined by ALT (serum alanine transaminase levels), and histologic hepatic damage (Metavir score A and F), but there was a positive relationship between the presence of a core-specific T cell responses and the viraemia.  相似文献   
996.
Dental anomalies occur frequently in a number of genetic disorders and act as major signs in diagnosing these disorders. We present definitions of the most common dental signs and propose a classification usable as a diagnostic tool by dentists, clinical geneticists, and other health care providers. The definitions are part of the series Elements of Morphology and have been established after careful discussions within an international group of experienced dentists and geneticists. The classification system was elaborated in the French collaborative network “TÊTECOU” and the affiliated O‐Rares reference/competence centers. The classification includes isolated and syndromic disorders with oral and dental anomalies, to which causative genes and main extraoral signs and symptoms are added. A systematic literature analysis yielded 408 entities of which a causal gene has been identified in 79%. We classified dental disorders in eight groups: dental agenesis, supernumerary teeth, dental size and/or shape, enamel, dentin, dental eruption, periodontal and gingival, and tumor‐like anomalies. We aim the classification to act as a shared reference for clinical and epidemiological studies. We welcome critical evaluations of the definitions and classification and will regularly update the classification for newly recognized conditions.  相似文献   
997.
998.
999.
1000.

Background

Few published breast cancer (BC) risk prediction models consider the heterogeneity of predictor variables between estrogen-receptor positive (ER+) and negative (ER-) tumors. Using data from two large cohorts, we examined whether modeling this heterogeneity could improve prediction.

Methods

We built two models, for ER+ (ModelER+) and ER- tumors (ModelER-), respectively, in 281,330 women (51% postmenopausal at recruitment) from the European Prospective Investigation into Cancer and Nutrition cohort. Discrimination (C-statistic) and calibration (the agreement between predicted and observed tumor risks) were assessed both internally and externally in 82,319 postmenopausal women from the Women’s Health Initiative study. We performed decision curve analysis to compare ModelER+ and the Gail model (ModelGail) regarding their applicability in risk assessment for chemoprevention.

Results

Parity, number of full-term pregnancies, age at first full-term pregnancy and body height were only associated with ER+ tumors. Menopausal status, age at menarche and at menopause, hormone replacement therapy, postmenopausal body mass index, and alcohol intake were homogeneously associated with ER+ and ER- tumors. Internal validation yielded a C-statistic of 0.64 for ModelER+ and 0.59 for ModelER-. External validation reduced the C-statistic of ModelER+ (0.59) and ModelGail (0.57). In external evaluation of calibration, ModelER+ outperformed the ModelGail: the former led to a 9% overestimation of the risk of ER+ tumors, while the latter yielded a 22% underestimation of the overall BC risk. Compared with the treat-all strategy, ModelER+ produced equal or higher net benefits irrespective of the benefit-to-harm ratio of chemoprevention, while ModelGail did not produce higher net benefits unless the benefit-to-harm ratio was below 50. The clinical applicability, i.e. the area defined by the net benefit curve and the treat-all and treat-none strategies, was 12.7?×?10??6 for ModelER+ and 3.0?×?10??6 for ModelGail.

Conclusions

Modeling heterogeneous epidemiological risk factors might yield little improvement in BC risk prediction. Nevertheless, a model specifically predictive of ER+ tumor risk could be more applicable than an omnibus model in risk assessment for chemoprevention.
  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