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   279796篇
  免费   9277篇
  国内免费   396篇
耳鼻咽喉   2278篇
儿科学   9397篇
妇产科学   4717篇
基础医学   31457篇
口腔科学   3837篇
临床医学   23072篇
内科学   52816篇
皮肤病学   2492篇
神经病学   27471篇
特种医学   13156篇
外国民族医学   6篇
外科学   43830篇
综合类   3673篇
一般理论   77篇
预防医学   26279篇
眼科学   4487篇
药学   16519篇
中国医学   742篇
肿瘤学   23163篇
  2023年   556篇
  2022年   1101篇
  2021年   2240篇
  2020年   1380篇
  2019年   2092篇
  2018年   24096篇
  2017年   18978篇
  2016年   21349篇
  2015年   3442篇
  2014年   4138篇
  2013年   5205篇
  2012年   13689篇
  2011年   27562篇
  2010年   22557篇
  2009年   15007篇
  2008年   25276篇
  2007年   27885篇
  2006年   6655篇
  2005年   8190篇
  2004年   9047篇
  2003年   9357篇
  2002年   7490篇
  2001年   2311篇
  2000年   2386篇
  1999年   1985篇
  1998年   1481篇
  1997年   1256篇
  1996年   944篇
  1995年   975篇
  1994年   847篇
  1993年   746篇
  1992年   1346篇
  1991年   1301篇
  1990年   1248篇
  1989年   1169篇
  1988年   1062篇
  1987年   978篇
  1986年   995篇
  1985年   973篇
  1984年   758篇
  1983年   689篇
  1982年   636篇
  1981年   496篇
  1980年   491篇
  1979年   584篇
  1978年   478篇
  1977年   419篇
  1975年   376篇
  1974年   433篇
  1973年   411篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Relationship-centered care reflects both knowing and feeling: the knowledge that physician and patient bring from their respective domains of expertise, and the physician’s and patient’s experience, expression, and perception of emotions during the medical encounter. These processes are conveyed and reciprocated in the care process through verbal and nonverbal communication. We suggest that the emotional context of care is especially related to nonverbal communication and that emotion-related communication skills, including sending and receiving nonverbal messages and emotional self-awareness, are critical elements of high-quality care. Although nonverbal behavior has received far less study than other care processes, the current review argues that it holds significance for the therapeutic relationship and influences important outcomes including satisfaction, adherence, and clinical outcomes of care.  相似文献   
72.
Coronary flow reserve (CFR) has been used toassess coronary microcirculation and epicardial coro-nary stenoses[1— 3 ] . CFR is defined as the ratio ofcoronary flow under maximal coronary vasodilatationto coronary flow under resting conditions[4 ] .Whenthe cross- sectional area of epicardial coronary arteriesis constant,coronary flow velocity (CFV) ratios areequal to volume flow ratios.The most common method used clinically formeasuring CFVR is intracoronary Doppler flow(ICD) analysis re…  相似文献   
73.
74.
1 Intravenous administration of the ganglionic nicotinic receptor agonist DMPP (1,1-dimethyl-4-phenylpiperazinium iodide) into urethane-anaesthetized rats evoked dose-dependent increases in mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA). 2 The ganglionic nicotinic receptor antagonists pentolinium and hexamethonium either alone or combined did not inhibit the increase in RSNA and MAP evoked by 50 to 200 μg kg?1 doses of DMPP. The increase in renal sympathetic nerve activity evoked by DMPP occurred as a brief burst in firing. 3 The increase in MAP, but not RSNA, evoked by DMPP in the presence of pentolinium was inhibited by the selective α1-adrenergic receptor antagonist prazosin. 4 The non-selective α-adrenoceptor and NPY receptor antagonist benextramine also inhibited the increase in MAP without inhibiting the increase in RSNA. Surprisingly, the combination of benextramine and pentolinium, or benextramine and hexamethonium, completely blocked the DMPP-evoked increase in RSNA and thus the increase in MAP. 5 The uptake1 antagonist desipramine combined with pentolinium did not affect the DMPP-evoked increases in MAP or RSNA when compared to the responses evoked in the presence of pentolinium alone. 6 Adding the selective M1 muscarinic receptor antagonist telenzepine to pentolinium and prazosin did not inhibit the increase in RSNA evoked by a 100 μg kg?1 dose of DMPP. 7 While the DMPP-evoked increase in MAP in the presence of ganglionic nicotinic receptor antagonists is primarily dependent upon activation of α1-adrenoceptors, the increase in RSNA occurs via activation of ganglionic nicotinic receptors and activation of a mechanism susceptible to blockade by benextramine.  相似文献   
75.
76.
77.
Unilateral microinjection of the acetylcholine receptor agonist carbachol into the posterior hypothalamic nucleus evokes a pressor response in the conscious, freely moving rat. To further localize this response 3.3 or 5.5 nmol of carbachol was microinjected in a volume of 50 nl directly into and outside the region of the posterior hypothalamic nucleus. Administration of carbachol outside the posterior hypothalamic nucleus failed to evoke a change in blood pressure indicating that the carbachol-induced pressor response is mediated from the posterior hypothalamic nucleus. Since posterior hypothalamic administration of atropine completely blocks the carbachol-induced increase in blood pressure and atropine blocks the three pharmacologically identified muscarinic receptor subtypes, methylatropine and progressively more selective muscarinic antagonists were administered into the posterior hypothalamic nucleus prior to 5.5 nmol of carbachol. Microinjection of the M1/M2/M3 muscarinic antagonist methylatropine (0.19-12.5 nmol), the M1/M3 antagonist 4-DAMP (4-diphenylacetoxy-N-methylpiperidine; 0.9-3.6 nmol), the M1 antagonist pirenzepine (9.5-38 nmol), the M2 antagonist methoctramine (5.5-44 nmol), or the M3 antagonist p-F-HHSiD (para-fluoro-hexahydro-sila-difenidol; 2.1-8.3 nmol) inhibited the peak increase in mean arterial pressure and the area under the curve of the change in mean arterial pressure versus time plot in a dose-dependent manner. Log ID50s calculated for the antagonists from the dose-response curves were found to correlate significantly with the log Kis of the antagonists for the muscarinic M3 receptor subtype. These results demonstrate that the increase in mean arterial pressure evoked by microinjection of carbachol into the posterior hypothalamic nucleus is mediated by the muscarinic M3 receptor.  相似文献   
78.
We reported recently that a novel immunomodulator, 7-thia-8-oxoguanosine (7T80G)2 inhibited formation of pulmonary melanoma metastases (1), prevented against viral infection in mice (2) and potentiated the efficacy of a weakly immunogenic leukemia vaccine (3). Since certain tumor metastases and virus infected cells are targets to natural killer cells (NK cells), we now investigated whether 7T80G is capable of activating NK cells in mice using NK cell sensitive YAC-1 and B16 and NK cell insensitive P815 targets. CBA/CaJ spleen cells incubated in vitro with 7T80G at concentrations ranging from 0.005 to 0.5 mM responded with increased NK cell activity (32-62 %) compared to controls (4-8%) to YAC-1 targets. Similar levels of augmentation in NK cell activity were observed when 40-168 mg/kg of 7T80G was administered in vivo. In addition to the spleen, 7T80G activated NK cells in the bone marrow (BM), the lungs, the liver, and in peritoneal exudate cells (PE). Although 7T80G elicited activation of NK cells was observed as early as three hours after treatment, the maximal activity was observed after 24 h in the spleen; 12 h in the BM; 48 h in the lungs, and 72 h in PE. Administration of the drug by s.c, i.v., and i.p. routes all induced activition of NK cells in spleen, BM and PE. 7T80G was found to activate NK cells in seven inbred and an outbred mouse strain, suggesting that the induced cytotoxicity against allogeneic and syngeneic tumor cells is not strain specific as well as independent of MHC restriction. C3H/He, CBA/CaJ and BDF/1 displayed higher levels of increased NK cell activity, whereas AKR mice were low responders. Low concentrations of IL-2 (0.25-5 U/ml) that induce little or no NK cell activity, when used in combination with 7T80G, elicited significant enhancement of NK cell cytotoxicity. In contrast, IFN and 7T80G showed no such synergism.  相似文献   
79.
BACKGROUND: The blood flow to the acetabular fragment is of some concern in juxtaarticular pelvic osteotomies used for the treatment of hip dysplasia. No direct measurements have determined the effect of the Bernese periacetabular osteotomy (PAO) on acetabular perfusion. METHODS: Acetabular perfusion was measured by means of laser Doppler flowmetry in 10 patients undergoing a PAO for symptomatic acetabular dysplasia. During the surgical procedure, the intraosseous high energy laser Doppler reliably depicts dynamic changes of small vessel blood flow. Measurements were performed after defined surgical steps to obtain sequential information on the blood perfusion of the acetabular fragment. RESULTS: After complete separation of the acetabular fragment, nine out of 10 patients had pulsatile signals, but the blood flow (BF) significantly decreased by 77%. Corrective positioning of the fragment induced no further drop of the BF signal but a loss of pulsatility in six patients. After a recovery period of about 30 min following preliminary fixation of the fragment, reestablishment of the pulsatile signal and an increase of the BF signal was seen. At termination of the surgical procedure, five out of eight patients, who could be followed throughout the whole procedure, showed a clear pulsatile signal in the supraacetabular area. Bleeding of the supraacetabular cancellous surface could be observed in all acetabula. CONCLUSION: Despite careful preservation of soft tissues during the surgical procedure, a significant reduction of the blood flow in the supraacetabular region has been observed. Nevertheless, a pulsatile signal in more than 60% of the fragments after fragment correction and an increasing signal during the recovery period showed ongoing blood perfusion indicating reversible changes in the measured supraacetabular area. All osteotomies healed within eight weeks without showing signs of necrosis during a minimum follow up of 1 year.  相似文献   
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