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   78724篇
  免费   5418篇
  国内免费   2158篇
耳鼻咽喉   185篇
儿科学   2376篇
妇产科学   2383篇
基础医学   7617篇
口腔科学   479篇
临床医学   11680篇
内科学   12585篇
皮肤病学   384篇
神经病学   3707篇
特种医学   2987篇
外国民族医学   4篇
外科学   5521篇
综合类   13973篇
现状与发展   6篇
预防医学   5293篇
眼科学   705篇
药学   7432篇
  84篇
中国医学   7271篇
肿瘤学   1628篇
  2024年   202篇
  2023年   1056篇
  2022年   1811篇
  2021年   2924篇
  2020年   2739篇
  2019年   2276篇
  2018年   2186篇
  2017年   2395篇
  2016年   2504篇
  2015年   2486篇
  2014年   4737篇
  2013年   5196篇
  2012年   4249篇
  2011年   4547篇
  2010年   3640篇
  2009年   3360篇
  2008年   3458篇
  2007年   3568篇
  2006年   3262篇
  2005年   2989篇
  2004年   2672篇
  2003年   2410篇
  2002年   2107篇
  2001年   2021篇
  2000年   1651篇
  1999年   1446篇
  1998年   1310篇
  1997年   1410篇
  1996年   1134篇
  1995年   1133篇
  1994年   1089篇
  1993年   831篇
  1992年   792篇
  1991年   723篇
  1990年   570篇
  1989年   550篇
  1988年   532篇
  1987年   435篇
  1986年   404篇
  1985年   595篇
  1984年   509篇
  1983年   312篇
  1982年   451篇
  1981年   337篇
  1980年   288篇
  1979年   213篇
  1978年   177篇
  1977年   159篇
  1976年   144篇
  1975年   74篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
81.
PURPOSE: The main objectives of this study were to determine the differences between non-synchronized intraocular pressure (IOP_N) and intraocular pressure readings synchronized with cardiac pulse and try to determine if these parameters are related to blood pressure values. METHODS: One hundred and sixty-five right eyes from 165 volunteers (107 females, 58 males) aged from 19 to 73 years (mean +/- S.D., 29.93 +/- 11.17) were examined with the Nidek NT-4000, a new non-contact tonometer that allows the measurement of IOP synchronized with the cardiac rhythm. IOP measurements in the four different modes of synchronization were taken in a randomized order. Three measures of each parameter were taken and then averaged. The blood pressure was determined three times with a portable manometer and mean values of systolic and diastolic pressure and the pulse rate were computed. Mean arterial pressure (MAP) was determined as being 1/3 of systolic plus 2/3 of diastolic blood pressure. RESULTS: The mean +/- S.D. values for the standard intraocular pressure (IOP_N: 14.76 +/- 2.86), intraocular pressure in the systolic instant or peak (IOP_P: 14.99 +/- 2.85), intraocular pressure in the middle instant between heartbeats or middle (IOP_M: 14.68 +/- 2.76), and intraocular pressure in the diastolic instant or bottom (IOP_B: 13.86 +/- 2.61) were obtained. The IOP_P was higher than the remaining values. A significant difference in mean IOP existed between IOP_B and the remaining modes of measuring (p < 0.05). Differences were statistically significant for all pair comparisons involving IOP_B. Arterial blood pressure values were systolic 125.5 +/- 14.22, diastolic 77.7 +/- 8.38 and MAP 93.64 +/- 9.44 mmHg. The pulse rate was 77.3 +/- 12.6 beats per minute. Except for the MAP (p = 0.025) there was no significant correlation between different IOP values and systolic or diastolic blood pressure, or pulse rate. CONCLUSIONS: NT-4000 is able to differentiate IOP values when synchronized with the cardiac rhythm and those differences are expected to be within a range of +/-2.5 to +/- 3.0 mmHg. IOP_B seems to be the parameter whose value differs from the non-synchronized and the remaining synchronized parameters in a significant way. Other than a weak association with MAP, no significant correlation between IOP and BP was found. The measurements of IOP readings for the three modes are consistent with timings during the cardiac cycle and IOP pulse cycle.  相似文献   
82.
AbstractBackground and Purpose: Polymorphonuclear neutrophils (PMNs) protect the host from invading microorganisms, but excessive PMN activation after trauma causes tissue injury. Rapid monitoring of PMN function is critical for the assessment of the inflammatory state of trauma patients. Here, the authors adapted two simple and rapid methods to measure oxidative burst and degranulation of human PMNs in whole blood to avoid potential interference of cell isolation procedures with the assessment of PMN function.Material and Methods: Heparinized blood was drawn from healthy volunteers or trauma patients, preincubated at 37 °C for 5 min, and stimulated with N-formyl-methionyl-leucyl-phenylalanine (fMLP). Four assays for oxidative burst were tested: (1) cytochrome C; (2) homovanillic acid (HVA); (3) Amplex® Red; and (4) flow cytometry with dihydrorhodamine 123 (DHR). PMN degranulation was assessed with flow cytometry using antibodies to: (1) CD11b/Mac-1 (CD18); (2) CD63; and (3) CD66b (CD67).Results: With the exception of the DHR method, all methods to measure oxidative burst were found to be unsuitable in whole blood due to interference of plasma proteins and hemoglobin with the fluorimetric or photometric readouts. By contrast, all degranulation methods were suitable for whole-blood studies. However, for the assessment of formyl peptide-induced degranulation, anti-antibodies to CD11b/Mac-1 and CD66b were up to five times more sensitive than antibodies to CD63. Thus, the degranulation and DHR methods were optimized for increased sensitivity, speed, and specificity and their usefulness to measure PMN function in trauma patients was tested.Conclusion: The whole-blood methods based on flow cytometry with DHR, anti-CD11b/Mac-1, and anti- CD66b are rapid, simple, and reliable techniques to assess PMN function for trauma research.  相似文献   
83.
肌病肾病代谢综合征治疗进展   总被引:1,自引:0,他引:1  
肌病肾病代谢综合征是急性动脉阻塞致骨骼肌溶解的严重并发症。积极治疗原发病,及早补液扩容、碱化尿液、早期血液净化治疗是降低截肢率、病死率的关键。本文就肌病肾病代谢综合征治疗进展作一综述。  相似文献   
84.
85.
Carotid baroreflex function ceases during vasovagal syncope   总被引:2,自引:0,他引:2  
Abstract. Despite the arterial baroreflex control of heart rate and blood pressure, vasovagal syncope is a common cause of loss of consciousness in people exposed to stimuli that reduce the central blood volume, such as head-up tilt. Carotid baroreflex function was evaluated using a rapid pulse train of neck pressure and neck suction in three conscious volunteers who developed a vasovagal episode during head-up tilt. The maximal gain of the carotid-heart rate and carotid-blood pressure baroreflex function curves were identified as measures of carotid baroreceptor responsiveness. When presyncopal symptoms developed, one further baroreflex assessment was obtained before the subjects were returned to the supine position. The bradycardia and hypotension exhibited during pre-syncope and syncope reflected a leftward and downward relocation of both the cardiac and vasomotor stimulusresponse curves. In addition, during the vasovagal syncope, baroreflex control was suppressed as blood pressure remained low during neck pressure stimuli. In conclusion, arterial baroreflex function ceases during vasovagal syncope.  相似文献   
86.
N‐acyl‐dopamines are a novel class of biologically active lipids that have recently been identified in the brain and have the potential to interact with neural signaling pathways. This study seeks to determine the ability of N‐oleoyl‐dopamine, a synthetic amide of oleic acid and dopamine, to cross the blood brain barrier. We determined the tissue content of radioactivity in selected brain regions, in a short‐run study design, following injections of [3H]N‐oleoyl‐dopamine (0.4 µCi) into the internal carotid artery in the rat. These results were compared with intracarotid injections of [3H]dopamine and with intravenous injections of both radiolabeled compounds. The level of radioactivity was determined using liquid scintillation and was expressed as the percentage of its total dose injected per gram of tissue. We found that the 15‐min brain uptake of radioactivity, with no distinct regional variations, amounted to about 6% following the intracarotid [3H]N‐oleoyl‐dopamine, which was a significant 3–4‐fold increase over that following similar administration of [3H]dopamine. Intravenous injections of [3H]N‐oleoyl‐dopamine gave a much smaller yield of radioactivity in brain tissue samples which was still severalfold greater than that for intravenous [3H]dopamine. Qualitative thin‐layered chromatography screening showed the presence of unchanged N‐oleoyl‐dopamine in the brain following injections. We conclude that N‐oleoyl‐dopamine has an appreciable ability to cross the blood‐brain barrier, which contrasts the limited transfer of dopamine alone. N‐oleoyl‐dopamine might exert physiological effects due to its known affinity for the central vanilloid receptors or to better satisfying the brain tissue demand for dopamine. The study suggests a potential pharmacological role for N‐oleoyl‐dopamine delivered exogenously in helping regulate the brain function. Drug Dev. Res. 60:217–224, 2003. © 2003 Wiley‐Liss, Inc.  相似文献   
87.
Trenkwalder P, Plaschke M, Aulehner R, Lydtin H. Felodipine or Hydrochlorothiazide/Triamterene for Treatment of' Hypertension in the Elderly: Effects on Blood Pressure, Hypertensive Heart Disease, Metabolic and Hormonal Parameters.

The aim of the study was to compare the antihypertensive efficacy of either felodipine or the diuretic combination hydrochlorothiazide/triamterene in a group (n = 65) of elderly (≥70 years) hypertensives (office blood pressure ≥ 60/95 mmHg) with special regard to ambulatory blood pressure monitoring, hypertensive heart disease and metabolic parameters. This was a randomized, double-blind study with a treatment period of 6 months. Reduction of office and 24-hr ambulatory blood pressure was comparable with both treatment regimens; after 6 months, 18 of 29 patients in the felodipine group (62%) and 20 of 27 patients in the diuretic group (74%; p = 0.4) were controlled. While episodes of ischemic type ST-segment depression were significantly reduced in the felodipine group (from 49 to 9 episodes), there was no significant change in the diuretic group (from 24 to 21 episodes). Both regimens decreased left ventricular wall thickness, but the decline in left ventricular muscle mass index was significant only for felodipine. Felodipine did not induce any change in metabolic or hormonal parameters; the diuretic combination significantly increased serum creatinine, uric acid, plasma renin activity, and plasma prorenin. Thus, the antihypertensive efficacy of felodipine and the diuretic combination was comparable in elderly hypertensives; only felodipine, however, improved parameters of hypertensive heart diesease and showed a neutral metabolic and hormonal profile.  相似文献   
88.
光照疗法对新生儿红细胞谷胱甘肽还原酶活性的影响   总被引:3,自引:0,他引:3  
作者对光照疗法(光疗)前及光疗后于口服维生素B_2(43例)和不予口服维生素B_2(17例)的黄疸新生儿的红细胞谷胱甘肽还原酶(GR)的活性进行了动态观察。结果显示,接受短期光疗的黄疸新生儿其红细胞GR活性较光疗前的GR活性有显著下降,光疗后予口服维生素B_2可使下降的红细胞GR活性回升,而不予补充维生素B_2者的红细胞GR活性继续下降。光疗的时间越长,红细胞GR活性的下降越明显,补充维生素B_2使红细胞GR活性回复到正常水平所需的时间也越长。短期光疗也可引起体内维生素B_2的降解,导致红细胞GR活性的下降,为避免因红细胞GR活性下降引起的红细胞额外破坏,对接受光疗的黄疸新生儿常规补充维生素B_2的是必要的。  相似文献   
89.
Résumé  Le saccharose, administré à une concentration d’au moins 12% chez le nouveau-né à terme (24% chez le prématuré), en petite quantité (0,05 à 2 ml), dans une seringue ou mieux dans une tétine, 2 minutes avant la réalisation d’un soin douloureux avec effraction cutanée (microprélèvement, ponction veineuse), permet de réduire, plus rarement d’abolir, les comportements de détresse et/ou de douleur (pleurs et manifestations faciales). Il s’agit d’un moyen simple, non médicamenteux, et utilisable partout, qui doit pouvoir représenter une aide non négligeable chez les nouveau-nés, pour la prise en charge de la douleur provoquée par des soins modérément douloreux. Il peut être utilisé seul, mais son action limitée rend préférable de l’envisager comme technique adjuvante. Son mode d’action reste encore peu clair, ainsi que sa tolérance en cas d’administrations pluri-quotidiennes.
Summary  Sucrose of at least 12% concentration delivered to full-term infants (24% concentration for preterm infants), in a small volume of 0.05 to 2 ml, through a syringue or better through a pacifier, 2 minutes before blood sample such as heel-stick or venipuncture, can attenuate or hardly abolish stress and/ or pain (crying and facial expressions). It is a simple non pharmacological treatment, helpful in the management of pain related to moderate painful procedures. As it exerts moderate effects, it is better used as an adjuvant treatment than used alone. Mechanisms of effects are not clear yet, as well as the occurrence of adverse effects when repeated daily administrations.
  相似文献   
90.
用蛋白胨、三油酸甘油酯、鼠肝、葡萄糖等材料模拟血清标本,通过测定该血清中蛋白、血脂、谷丙转氨酶、血糖以及部分物理参数,探讨了模拟血清从外观和实验项目上满足实验教学的可行性。结果表明,模拟血清实用、简便易得,既能解决医学生物化学实验教学标本来源困难问题,又能防止实验室污染和节省大量实验经费。  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