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   7908篇
  免费   586篇
  国内免费   36篇
耳鼻咽喉   76篇
儿科学   238篇
妇产科学   235篇
基础医学   1181篇
口腔科学   140篇
临床医学   858篇
内科学   1613篇
皮肤病学   206篇
神经病学   762篇
特种医学   165篇
外科学   693篇
综合类   73篇
一般理论   9篇
预防医学   934篇
眼科学   119篇
药学   644篇
中国医学   19篇
肿瘤学   565篇
  2024年   12篇
  2023年   85篇
  2022年   158篇
  2021年   310篇
  2020年   190篇
  2019年   262篇
  2018年   290篇
  2017年   186篇
  2016年   241篇
  2015年   265篇
  2014年   332篇
  2013年   417篇
  2012年   679篇
  2011年   684篇
  2010年   396篇
  2009年   308篇
  2008年   529篇
  2007年   509篇
  2006年   498篇
  2005年   444篇
  2004年   371篇
  2003年   354篇
  2002年   319篇
  2001年   33篇
  2000年   32篇
  1999年   36篇
  1998年   61篇
  1997年   51篇
  1996年   33篇
  1995年   36篇
  1994年   31篇
  1993年   19篇
  1992年   16篇
  1991年   24篇
  1990年   13篇
  1989年   8篇
  1988年   13篇
  1987年   16篇
  1986年   16篇
  1985年   29篇
  1984年   16篇
  1983年   14篇
  1982年   17篇
  1981年   20篇
  1980年   21篇
  1979年   12篇
  1977年   8篇
  1974年   9篇
  1973年   12篇
  1928年   13篇
排序方式: 共有8530条查询结果,搜索用时 0 毫秒
91.
Once human photoreceptors die, they do not regenerate, thus, photoreceptor transplantation has emerged as a potential treatment approach for blinding diseases. Improvements in transplant organization, donor cell maturation, and synaptic connectivity to the host will be critical in advancing this technology for use in clinical practice. Unlike the unstructured grafts of prior cell-suspension transplantations into end-stage degeneration models, we describe the extensive incorporation of induced pluripotent stem cell (iPSC) retinal organoid–derived human photoreceptors into mice with cone dysfunction. This incorporative phenotype was validated in both cone-only as well as pan-photoreceptor transplantations. Rather than forming a glial barrier, Müller cells extended throughout the graft, even forming a series of adherens junctions between mouse and human cells, reminiscent of an outer limiting membrane. Donor-host interaction appeared to promote polarization as well as the development of morphological features critical for light detection, namely the formation of inner and well-stacked outer segments oriented toward the retinal pigment epithelium. Putative synapse formation and graft function were evident at both structural and electrophysiological levels. Overall, these results show that human photoreceptors interacted readily with a partially degenerated retina. Moreover, incorporation into the host retina appeared to be beneficial to graft maturation, polarization, and function.  相似文献   
92.
Macrophages are a diverse myeloid cell population involved in innate and adaptive immune responses, embryonic development, wound repair, and regulation of tissue homeostasis. These cells link the innate and adaptive immunities and are crucial in the development and sustainment of various inflammatory diseases. Macrophages are tissue-resident cells in steady-state conditions; however, they are also recruited from blood monocytes after local pathogen invasion or tissue injury. Peritoneal macrophages vary based on their cell complexity, phenotype, and functional capabilities. These cells regulate inflammation and control bacterial infections in the ascites of decompensated cirrhotic patients. Our recent work reported several phenotypic and functional characteristics of these cells under both healthy and pathological conditions. A direct association between cell size, CD14/CD16 expression, intracellular level of GATA-6, and expression of CD206 and HLA-DR activation/maturation markers, indicate that the large peritoneal macrophage CD14highCD16high subset constitutes the mature phenotype of human resident peritoneal macrophages during homeostasis. Moreover, elevated expression of CD14/CD16 is related to the phagocytic capacity. The novel large CD14highCD16high peritoneal subpopulation is increased in the ascites of cirrhotic patients and is highly sensitive to lipopolysaccharide (LPS)-induced activation, thereby exhibiting features of inflammatory priming. Thus, phosphorylation of ERK1/2, PKB/Akt, and c-Jun is remarkably increased in response to LPS in vitro, whereas that of p38 MAPK is reduced compared with the monocyte-derived macrophages from the blood of healthy controls. Furthermore, in vitro activated monocyte-derived macrophages from ascites of cirrhotic patients secreted significantly higher levels of IL-6, IL-10, and TNF-α and lower amounts of IL-1β and IL-12 than the corresponding cells from healthy donor’s blood. Based on these results, other authors have recently reported that the surface expression level of CD206 can be used to identify mature, resident, inflammatory peritoneal macrophages in patients with cirrhosis. Soluble CD206 is released from activated large peritoneal macrophages, and increased concentrations in patients with cirrhosis and spontaneous bacterial peritonitis (SBP) indicate reduced odds of survival for 90 d. Hence, the level of soluble CD206 in ascites might be used to identify patients with SBP at risk of death. In conclusion, peritoneal macrophages present in ascites of cirrhotic patients display multiple phenotypic modifications characterized by reduced ratio of cells expressing several membrane markers, together with an increase in the ratios of complex and intermediate subpopulations and a decrease in the classic-like subset. These modifications may lead to the identification of novel pharmaceutical targets for prevention and treatment of hepatic damage.  相似文献   
93.
BackgroundLittle is known on the current global prevalence of atopic dermatitis (AD) in the pediatric population.ObjectiveTo estimate the real-world global prevalence of AD in the pediatric population and by disease severity.MethodsThis international, cross-sectional, web-based survey of children and adolescents (6 months to <18 years old) was conducted in the following 18 countries: North America (Canada, United States), Latin America (Argentina, Brazil, Columbia, Mexico), Europe (France, Germany, Italy, Spain, United Kingdom), Middle East and Eurasia (Israel, Saudi Arabia, Turkey, United Arab Emirates, Russia), and East Asia (Japan, Taiwan). Prevalence was determined using the following 2 definitions: (1) diagnosed as having AD according to the International Study of Asthma and Allergies in Childhood (ISAAC) criteria and self- or parent-report of ever being told by a physician that they or their child child had AD (eczema); and (2) reported AD based on the ISAAC criteria only. Severity was assessed using the Patient Global Assessment (PtGA) and Patient-Oriented Eczema Measure (POEM).ResultsAmong 65,661 responders, the 12-month diagnosed AD prevalence (ISAAC plus self-reported diagnosis) ranged from 2.7% to 20.1% across countries; reported AD (ISAAC only) was 13.5% to 41.9%. Severe AD evaluated with both PtGA and POEM was generally less than 15%; more subjects rated AD as mild on PtGA than suggested by POEM. No trends in prevalence were observed based on age or sex; prevalence was generally lower in rural residential settings than urban or suburban.ConclusionThis global survey in 18 countries revealed that AD affects a substantial proportion of the pediatric population. Although prevalence and severity varied across age groups and countries, less than 15% had severe AD.  相似文献   
94.
95.
96.
97.
One hundred and twenty, full-term, normal, first-born infants were categorized at one month of age into a high-risk or low-risk group for possible development of emotional and developmental deviations. The predictions were based on measurements of the mother's perception of her infant as compared to the average. At age 4 1/2, the children were evaluated by two child psychiatrists who had no knowledge of the children's predictive risk rating. A statistically significant association was evident between prediction and outcome. This paper describes the methodology and discusses the implications of the findings.This paper was originally presented at American Psychiatric Association Meeting in Bal Harbour, Florida, May 8, 1969.The authors wish to express their appreciation to Mrs. Fredricka Latshaw, Dr. Sara Arnaud, Mr. Ted Grice, and Mrs. Karen Lento.  相似文献   
98.
99.
Background: Breast cancer (BC) is the most common and deadliest malignancy among women. High mammographic breast density (MBD) is an established modifiable risk marker for BC, and it is of interest, for prevention purposes, to consider lifestyle factors that may modulate both MBD and BC risk. Here, we conducted a systematic review of the most up-to-date evidence on the association between diet as a whole and MBD. Methods: We considered as eligible for inclusion in our review (PROSPERO registration code CRD42022335289) the studies published until 31 December 2021, that reported on the association between a priori or a posteriori dietary patterns (in observational studies) or dietary interventions (in randomized controlled trials) and MBD. Results: In total, twelve studies were included. MBD tended to be inversely associated with adherence to dietary patterns characterized by high consumption of plant-based foods and low in meat, animal fats, and alcohol, defined both a priori (e.g., Mediterranean diet and WCRF/AICR guidelines) or a posteriori (e.g., “fruit-vegetable-cereal” and “salad-sauce-pasta/grains” patterns). Findings from intervention studies were in fair agreement with those from observational studies. Conclusions: While further studies are needed, we found suggestive evidence that the adoption of a healthy diet is associated with lower MBD.  相似文献   
100.
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