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   38018篇
  免费   3176篇
  国内免费   82篇
耳鼻咽喉   289篇
儿科学   1703篇
妇产科学   1182篇
基础医学   5184篇
口腔科学   399篇
临床医学   4623篇
内科学   6957篇
皮肤病学   681篇
神经病学   4507篇
特种医学   720篇
外科学   3707篇
综合类   352篇
现状与发展   1篇
一般理论   74篇
预防医学   5170篇
眼科学   595篇
药学   2507篇
中国医学   35篇
肿瘤学   2590篇
  2024年   62篇
  2023年   577篇
  2022年   820篇
  2021年   1951篇
  2020年   1156篇
  2019年   1674篇
  2018年   1881篇
  2017年   1272篇
  2016年   1438篇
  2015年   1494篇
  2014年   1960篇
  2013年   2460篇
  2012年   3568篇
  2011年   3454篇
  2010年   1728篇
  2009年   1485篇
  2008年   2279篇
  2007年   2367篇
  2006年   2000篇
  2005年   1834篇
  2004年   1567篇
  2003年   1295篇
  2002年   1166篇
  2001年   146篇
  2000年   107篇
  1999年   177篇
  1998年   230篇
  1997年   136篇
  1996年   115篇
  1995年   114篇
  1994年   106篇
  1993年   96篇
  1992年   55篇
  1991年   45篇
  1990年   42篇
  1989年   29篇
  1988年   26篇
  1987年   24篇
  1986年   28篇
  1985年   32篇
  1984年   30篇
  1983年   24篇
  1982年   25篇
  1981年   26篇
  1980年   29篇
  1979年   18篇
  1978年   15篇
  1977年   12篇
  1974年   8篇
  1972年   15篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
ABSTRACT

In South Africa, high attrition rates throughout the care continuum present major barriers to controlling the HIV epidemic. Mobile health (mHealth) interventions may provide innovative opportunities for efficient healthcare delivery and improving retention in care. In this formative research, we interviewed 11 patients and 28 healthcare providers in North West Province, South Africa, to identify perceived benefits, concerns and suggestions for a future mHealth program to deliver HIV Viral Load and CD4 Count test results directly to patients via mobile phone. Thematic analysis found that reduced workload for providers, reduced wait times for patients, potential expanded uses and patient empowerment were the main perceived benefits of an mHealth program. Perceived concerns included privacy, disseminating distressing results through text messages and patients’ inability to interpret results. Participants felt that an mHealth program should complement face-to-face interactions and educational information to interpret results is needed. Providers identified logistical considerations and suggested protocols be developed. An mHealth program to deliver HIV test results directly to patients could mitigate multiple barriers to care but needs to be tested for efficacy. Concerns identified by patients and providers must be addressed in designing the program to successfully integrate with health facility workflow and ensure its sustainability.  相似文献   
992.
We have found in chronically hypoxic rats that acute intravenous administration of the Rho kinase inhibitor Y-27632 nearly normalizes the pulmonary hypertension (PH) but has no pulmonary vascular selectivity. In this study, we tested if oral or inhaled Y-27632 would be an effective and selective pulmonary vasodilator in hypoxic PH. Although acute oral Y-27632 caused a marked and sustained decrease in mean pulmonary arterial pressure (MPAP), it also decreased mean systemic arterial pressure (MSAP). In contrast, 5 minutes of inhaled Y-27632 decreased MPAP without reducing MSAP. The hypotensive effect of inhaled Y-27632 on hypoxic PH was greater than that of inhaled nitric oxide, and the effect lasted for at least 5 hours. Inhaled fasudil, another Rho kinase inhibitor, caused selective MPAP reductions in monocrotaline-induced PH and in spontaneous PH in fawn-hooded rats, as well as in chronically hypoxic rats. These results suggested that inhaled Y-27632 was more effective than inhaled nitric oxide as a selective pulmonary vasodilator in hypoxic PH, and that Rho kinase-mediated vasoconstriction was also involved in the other models of PH. Inhaled Rho kinase inhibitors might be useful for acute vasodilator testing in patients with PH, and future work should evaluate their efficacy in the long-term treatment of PH.  相似文献   
993.
Dyskeratosis congenita (DC) is an inherited bone marrow (BM) failure syndrome associated with mutations in telomerase genes and the acquisition of shortened telomeres in blood cells. To investigate the basis of the compromised hematopoiesis seen in DC, we analyzed cells from granulocyte colony-stimulating factor mobilized peripheral blood (mPB) collections from 5 members of a family with autosomal dominant DC with a hTERC mutation. Premobilization BM samples were hypocellular, and percentages of CD34+ cells in marrow and mPB collections were significantly below values for age-matched controls in 4 DC subjects. Directly clonogenic cells, although present at normal frequencies within the CD34+ subset, were therefore absolutely decreased. In contrast, even the frequency of long-term culture-initiating cells within the CD34+ DC mPB cells was decreased, and the telomere lengths of these cells were also markedly reduced. Nevertheless, the different lineages of mature cells were produced in normal numbers in vitro. These results suggest that marrow failure in DC is caused by a reduction in the ability of hematopoietic stem cells to sustain their numbers due to telomere impairment rather than a qualitative defect in their commitment to specific lineages or in the ability of their lineage-restricted progeny to execute normal differentiation programs.  相似文献   
994.
A fundamental property of platelets is their ability to transmit cytoskeletal contractile forces to extracellular matrices. While the importance of the platelet contractile mechanism in regulating fibrin clot retraction is well established, its role in regulating the primary hemostatic response, independent of blood coagulation, remains ill defined. Real-time analysis of platelet adhesion and aggregation on a collagen substrate revealed a prominent contractile phase during thrombus development, associated with a 30% to 40% reduction in thrombus volume. Thrombus contraction developed independent of thrombin and fibrin and resulted in the tight packing of aggregated platelets. Inhibition of the platelet contractile mechanism, with the myosin IIA inhibitor blebbistatin or through Rho kinase antagonism, markedly inhibited thrombus contraction, preventing the tight packing of aggregated platelets and undermining thrombus stability in vitro. Using a new intravital hemostatic model, we demonstrate that the platelet contractile mechanism is critical for maintaining the integrity of the primary hemostatic plug, independent of thrombin and fibrin generation. These studies demonstrate an important role for the platelet contractile mechanism in regulating primary hemostasis and thrombus growth. Furthermore, they provide new insight into the underlying bleeding diathesis associated with platelet contractility defects.  相似文献   
995.
996.
997.
This study tested the hypothesis that very late antigen (VLA)-4 mediates CD18-independent neutrophil emigration into the airspaces induced by either Streptococcus pneumoniae, a stimulus that induces primarily CD18-independent neutrophil emigration, or Escherichia coli, toward which only 20-30% of the total number of neutrophils emigrate through CD18-independent pathways. In wild-type (WT) mice, VLA-4 expression was less on neutrophils that emigrated into the airspaces than on circulating neutrophils. Vascular cell adhesion molecule-1 (VCAM-1) mRNA, the major endothelial cell ligand for VLA-4, increased more in E. coli than in S. pneumoniae pneumonia. VCAM-1 protein expression was not detected in capillaries, the major site of neutrophil emigration. Neutrophil emigration during E. coli or S. pneumoniae pneumonia was similar in mice given antibodies against both CD18 and VLA-4 compared with mice given the anti-CD18 antibody and a control antibody. However, in hematopoietically reconstituted mice with both WT and CD18-deficient neutrophils in their blood, the migration of CD18-deficient neutrophils in response to S. pneumoniae was slightly but significantly less in animals pretreated with the anti-VLA-4 antibody than in those receiving a control antibody. These data suggest that VLA-4 plays a small role in CD18-independent neutrophil emigration, but the majority of CD18-independent neutrophil emigration induced by bacteria in the lungs occurs through VLA-4-independent mechanisms.  相似文献   
998.
999.
The Steroidogenic Acute Regulatory (StAR) protein is a mitochondrial protein required for the transport of cholesterol substrate to the P450scc enzyme located in the inner mitochondrial membranes of steroid producing cells. This study suggests that the acute regulation of the rodent StAR gene in the ovary is mediated by two factors, C/EBPbeta and GATA-4. Once translated, the StAR precursor protein is either imported into the mitochondria, or it is rapidly degraded in the cytosol. We predicted that in order to perpetuate StAR activity cycles, imported StAR should turn over rapidly to avoid a potentially harmful accumulation of the protein in sub-mitochondrial compartments. Pulse-chase experiments in metabolically labeled cells showed that: (a) the turnover rate of mature mitochondrial StAR protein (30 kDa) is much faster (t(1/2) = 4-5 h) than that of other mitochondrial proteins; (b) dissipation of the inner membrane potential (-delta psi) by carbonyl cyanide m-chlorophenylhydrazone (mCCCP) accelerates the mitochondrial degradation of StAR; (c) unexpectedly, the mitochondrial degradation of StAR is inhibited by MG132 and lactacystin, but not by epoxomicin. Furthermore, StAR degradation becomes inhibitor-resistant two hours after import. Therefore, these studies suggest a bi-phasic route of StAR turnover in the mitochondria. Shortly after import, StAR is degraded by inhibitor-sensitive protease(s) (phase I), whereas at later times, StAR turnover proceeds to completion through an MG132-resistant proteolytic activity (phase II). Collectively, this study defines StAR as a unique protein that can authentically be used to probe multiple proteolytic activities in mammalian mitochondria.  相似文献   
1000.

Objective

To develop a framework for a successful rural family medicine training program and to assess the potential for a rural family medicine residency training program using the Weyburn and Estevan areas of Saskatchewan as test sites.

Design

A mixed-method design was used; however, the focus of this article was on the qualitative data collected. Questions formulated for the semistructured interviews evolved from the literature.

Setting

Rural Saskatchewan.

Participants

Community physicians and representatives from the Sun Country Regional Health Authority, the Saskatchewan Ministry of Health, and the University of Saskatchewan.

Methods

The data were documented during the interviews using a laptop computer, and the responses were reviewed with participants at the end of their interviews to ensure accuracy. The qualitative data collected were analyzed using inductive thematic analysis.

Main findings

Through the analysis of the data several themes emerged related to implementing a rural family medicine residency training program. Key predictors of success were physical resources, physician champions, physician teachers, educational support, administrative support, and other specialist support. Barriers to the development of a rural family medicine training site were differing priorities, lack of human resources, and lack of physical resources.

Conclusion

A project of this magnitude requires many people at different levels collaborating to be successful.  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