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   2524篇
  免费   165篇
  国内免费   11篇
耳鼻咽喉   14篇
儿科学   99篇
妇产科学   26篇
基础医学   460篇
口腔科学   66篇
临床医学   255篇
内科学   432篇
皮肤病学   65篇
神经病学   262篇
特种医学   128篇
外科学   214篇
综合类   21篇
一般理论   1篇
预防医学   127篇
眼科学   47篇
药学   203篇
中国医学   7篇
肿瘤学   273篇
  2024年   5篇
  2023年   18篇
  2022年   43篇
  2021年   56篇
  2020年   58篇
  2019年   42篇
  2018年   62篇
  2017年   57篇
  2016年   59篇
  2015年   89篇
  2014年   88篇
  2013年   112篇
  2012年   161篇
  2011年   181篇
  2010年   96篇
  2009年   117篇
  2008年   183篇
  2007年   188篇
  2006年   161篇
  2005年   164篇
  2004年   167篇
  2003年   165篇
  2002年   153篇
  2001年   26篇
  2000年   14篇
  1999年   22篇
  1998年   22篇
  1997年   15篇
  1996年   21篇
  1995年   26篇
  1994年   14篇
  1993年   16篇
  1992年   9篇
  1991年   11篇
  1990年   8篇
  1989年   5篇
  1988年   7篇
  1987年   2篇
  1986年   7篇
  1985年   5篇
  1984年   8篇
  1983年   4篇
  1982年   6篇
  1981年   4篇
  1980年   7篇
  1979年   3篇
  1978年   2篇
  1975年   5篇
  1974年   2篇
  1973年   2篇
排序方式: 共有2700条查询结果,搜索用时 15 毫秒
71.
Digitization has long since taken hold in the diabetes sector. Digital support including pumps, rtCGM (CGM: continuous glucose monitoring, rtCGM: real time CGM), iscCGM (intermittent scanning CGM), apps as well as measuring devices with pattern recognition and a reminder function has become commonplace in many areas. Training to become a diabetes advisor provides diabetes professionals with appropriate basic knowledge to advise the patient in self-management with technical support. Continuous medical training to empower and support patients in health literacy, data protection and the use of telemedicine is imperative.  相似文献   
72.
73.
Hybrid organic–inorganic perovskite halides, and, in particular, their mixed halide solid solutions, belong to a broad class of materials which appear promising for a wide range of potential applications in various optoelectronic devices. However, these materials are notorious for their stability issues, including their sensitivity to atmospheric oxygen and moisture as well as phase separation under illumination. The thermodynamic properties, such as enthalpy, entropy, and Gibbs free energy of mixing, of perovskite halide solid solutions are strongly required to shed some light on their stability. Herein, we report the results of an experimental thermochemical study of the CH3NH3Pb(Cl1−xBrx)3 mixed halides by solution calorimetry. Combining these results with molecular dynamics simulation revealed the complex and irregular shape of the compositional dependence of the mixing enthalpy to be the result of a complex interplay between the local lattice strain, hydrogen bonds, and energetics of these solid solutions.  相似文献   
74.
75.
Endothelial hyperpermeability followed by edema formation is a hallmark of many severe disorders. Effective drugs directly targeting endothelial barrier function are widely lacking. We hypothesized that the hawthorn (Crataegus spp.) extract WS® 1442, a proven multi-component drug against moderate forms of heart failure, would prevent vascular leakage by affecting endothelial barrier-regulating systems. In vivo, WS® 1442 inhibited the histamine-evoked extravasation of FITC–dextran from mouse cremaster muscle venules. In cultured human endothelial cells, WS® 1442 blocked the thrombin-induced FITC–dextran permeability. By applying biochemical and microscopic techniques, we revealed that WS® 1442 abrogates detrimental effects of thrombin on adherens junctions (vascular endothelial-cadherin), the F-actin cytoskeleton, and the contractile apparatus (myosin light chain). Mechanistically, WS® 1442 inhibited the thrombin-induced rise of intracellular calcium (ratiometric measurement), followed by an inactivation of PKC and RhoA (pulldown assay). Moreover, WS® 1442 increased endothelial cAMP levels (ELISA), which consequently activated PKA and Rap1 (pulldown assay). Utilizing pharmacological inhibitors or siRNA, we found that PKA is not involved in barrier protection, whereas Epac1, Rap1, and Rac1 play a crucial role in the WS® 1442-induced activation of cortactin, which triggers a strong cortical actin rearrangement. In summary, WS® 1442 effectively protects against endothelial barrier dysfunction in vitro and in vivo. It specifically interacts with endothelial permeability-regulating systems by blocking the Ca2 +/PKC/RhoA and activating the cAMP/Epac1/Rap1 pathway. As a proven safe herbal drug, WS® 1442 opens a novel pharmacological approach to treat hyperpermeability-associated diseases. This in-depth mechanistic work contributes to a better acceptance of this herbal remedy.  相似文献   
76.
BACKGROUND AND METHODS: 5-Iodo-2'-deoxyuridine (IdUrd) radiolabelled with the positron emitter I or with the gamma and Auger electron emitters I or I has been proposed for cancer diagnosis and therapy. We modified the synthesis to reliably obtain [I]IdUrd and [I]IdUrd by using an Iodogen supported destannylation reaction of 5-(tri-n-butylstannyl)-2'-deoxyuridine (Bu3SndUrd) which meets the requirements for good laboratory practice (GLP) and good clinical practice (GCP). A method of purification was developed to eliminate by-products as well as any unreacted starting material. RESULTS: [I]IdUrd, which originated from a trace of iodide in the Bu3SndUrd precursor, was identified as the unknown by-product reported for this method. This trace could be eliminated by modified purification of Bu3SndUrd. Stabilization of pH was essential for unequivocal identification of radiolabelled IdUrd and possible degradation products in the different systems tested for quality control. Biodistribution in tumour bearing nude mice was measured as early as 3 and 6 h after i.v. injection of [I]IdUrd. This compound showed high and specific activity uptake in tumour and dividing tissues when combined with 5-fluoro-2'-deoxyuridine pre-treatment. Uptake was specifically inhibited by injection of excess thymidine.  相似文献   
77.
We have shown earlier that nicotinic agonists induce the release of noradrenaline from chick sympathetic neurons in culture in two ways: (a) by activating the postsynaptic nicotinic receptors on nerve cell bodies, giving rise to spreading electrical activity and opening of voltage operated calcium channels in neuronal processes; (b) by activating the presynaptic nicotinic receptors on neuronal processes. In the present work, we investigated the contribution of various pathways to the observed Ca2+ influx and subsequent noradrenaline release. Sympathetic neurons in culture were stimulated either by the nicotinic agonist dimethylphenylpiperazinium or electrically, in the presence or absence of tetrodotoxin and of specific blockers of calcium or nicotinic channels, and the effects on [Ca2+]i in the area of neuronal processes and on noradrenaline release were measured. Under control conditions, the N-type channel blocker ω-conotoxin (0.1 μmol/1) diminished the release of noradrenaline and the increase of intraterminal Ca2+ by 48% and 55%, respectively, whereas the L-type channel blocker (+)Bay k 8644 (1 μmol/1) diminished the release of noradrenaline by 25% and the increase of [Ca2+]i by 39%. The P-type channel blocker ω-agatoxin (0.3 μmol/1) had no effect. The effects of the L-type channel ligands were complex and could only be explained on the assumption that, at high concentrations, these drugs also act as nicotinic antagonists. Tetrodotoxin blocked the Ca2+ response evoked by electrical stimulation whereas DMPP applied in the presence of tetrodotoxin still evoked an increase of [Ca2+]i and the release of noradrenaline (27% and 30% of control without tetrodotoxin, respectively). These residual responses were not blocked by any of the calcium channel blockers used or by their combination. Apparently, a substantial part of the influx of Ca2+ induced by the activation of presynaptic nicotinic receptors is not carried by the N-, L- or P-type channels and probably occurs directly via the open channels of nicotinic receptors.  相似文献   
78.
Objective: To assess if adapted versions of the response restriction toilet training protocol, based on the behavioral phenotype of Angelman syndrome (AS), were successful in fostering urinary continence in seven individuals with AS.

Method: Data were collected in AB-designs during baseline, training, generalization and follow-up. The response restriction protocol was adapted: individuals were trained in their natural environment, were prompted to void and along with improving continence, the interval between voids was prolonged and time-on-toilet decreased.

Results: During generalization five individuals had less than two accidents and one to six correct voids per day; during baseline more accidents and/or less correct voids occurred. In two participants correct voids increased, but several accidents still occurred. Three participants maintained positive results after 3–18 months.

Conclusion: Despite their intellectual and behavioral challenges, urinary continence can be acquired in AS. Several indications of voiding dysfunctions were found; further research is indicated.  相似文献   

79.
80.
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