全文获取类型
收费全文 | 235908篇 |
免费 | 15430篇 |
国内免费 | 992篇 |
专业分类
耳鼻咽喉 | 2526篇 |
儿科学 | 6023篇 |
妇产科学 | 4429篇 |
基础医学 | 29461篇 |
口腔科学 | 4374篇 |
临床医学 | 24189篇 |
内科学 | 49860篇 |
皮肤病学 | 3249篇 |
神经病学 | 23722篇 |
特种医学 | 10151篇 |
外国民族医学 | 16篇 |
外科学 | 37184篇 |
综合类 | 2549篇 |
现状与发展 | 2篇 |
一般理论 | 185篇 |
预防医学 | 16618篇 |
眼科学 | 5595篇 |
药学 | 15546篇 |
1篇 | |
中国医学 | 325篇 |
肿瘤学 | 16325篇 |
出版年
2023年 | 1242篇 |
2022年 | 2183篇 |
2021年 | 5439篇 |
2020年 | 3101篇 |
2019年 | 5105篇 |
2018年 | 6120篇 |
2017年 | 4493篇 |
2016年 | 4870篇 |
2015年 | 5777篇 |
2014年 | 8406篇 |
2013年 | 11317篇 |
2012年 | 17374篇 |
2011年 | 18103篇 |
2010年 | 10112篇 |
2009年 | 9363篇 |
2008年 | 15920篇 |
2007年 | 16742篇 |
2006年 | 16263篇 |
2005年 | 16123篇 |
2004年 | 15171篇 |
2003年 | 13827篇 |
2002年 | 13235篇 |
2001年 | 1973篇 |
2000年 | 1460篇 |
1999年 | 2028篇 |
1998年 | 2798篇 |
1997年 | 2222篇 |
1996年 | 1926篇 |
1995年 | 1769篇 |
1994年 | 1529篇 |
1993年 | 1495篇 |
1992年 | 986篇 |
1991年 | 926篇 |
1990年 | 785篇 |
1989年 | 748篇 |
1988年 | 680篇 |
1987年 | 617篇 |
1986年 | 644篇 |
1985年 | 683篇 |
1984年 | 915篇 |
1983年 | 787篇 |
1982年 | 1036篇 |
1981年 | 966篇 |
1980年 | 838篇 |
1979年 | 466篇 |
1978年 | 514篇 |
1977年 | 446篇 |
1976年 | 420篇 |
1975年 | 315篇 |
1974年 | 310篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
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
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
952.
953.
Michael V. Hansen Helen Holmgren Anders Spberg Andrej Warycha 《Neurourology and urodynamics》1990,9(3):257-268
EMG responses in the external anal sphincter (EAS), the rectus abdominis muscle (RA), and the anterior tibial muscle (TA) were recorded following single magnetic transcranial cortical stimulations (TCCS) in seven healthy volunteers. The responses in the EAS differed from the responses in the other muscles. They had comparatively long durations ranging from 1 to 2 seconds, no inhibitory periods were observed, and there was no tendency for habituation to occur following a limited number of stimuli. The responses recorded in the EAS were used as test responses in order to evaluate the excitability changes in the EAS motoneurons occurring during bladder filling. Cystometries with filling rates of 15, 50 and 200 ml/min were done. During these cystometries TCCS were applied repeatedly, with constant strength, after each 50 ml of filling up to bladder capacity. The responses following TCCS changed in a highly reproducible way during bladder filling. After 100–200 ml of filling, the responses had longer latencies, diminished sizes, and shorter durations. When the filling reached a level 50–150 ml below capacity, the responses in most subjects again became greater and the latencies shorter. The changes were believed to be physiological. It was concluded that the EAS motoneurons are under both inhibitory and facilitatory influence during bladder filling in intact healthy humans. Facilitatory influences are often observed when the bladder is filled close to capacity. At lower bladder volumes the observed influence is always inhibitory. A decrease in the EMG activity of the EAS during filling cystometry should consequently not be regarded as a pathological response. 相似文献
954.
Rodney Harrison Michael J. Bronskill R. Mark Henkelman 《Magnetic resonance in medicine》1995,33(4):490-496
T2 relaxation makes an important contribution to tissue contrast in magnetic resonance (MR) imaging. Many tissues are known to exhibit multicomponent T2 relaxation that suggests some compartmental segregation of mobile protons on a T2 timescale. Magnetization transfer (MT) is another relaxation mechanism that can be used to produce tissue contrast in MR imaging. The MT process depends strongly on water-macromolecular interactions. To investigate the relationship between multicomponent T2 relaxation and the MT process, multiecho T2 measurements have been combined with MT measurements for freshly excised samples of cardiac muscle, striated muscle, and white matter. For muscle, short T2 components show greater MT than long T2 components, consistent with the belief that they represent distinct water environments. For white matter, quantitative MT measurements were identical for the two major T2 components, apparently because of exchange between the T2 compartments on a timescale characteristic of the MT experiment. Implications for accurate modeling of MT in tissue and the use of MT for MR image contrast are discussed. 相似文献
955.
John R. Graybill Laura K. Najvar Annette Fothergill Thomas Hardin Michael Rinaldi Chris Lambros Steven L. Regen 《Antimicrobial agents and chemotherapy》1998,42(1):147-150
KY-62 is a water-soluble analog of amphotericin B. In vitro testing of five clinical isolates of Candida albicans showed KY-62 to have potency similar to that of amphotericin B. KY-62 was administered to mice infected intravenously with C. albicans. In vivo, KY-62 was effective in immunocompetent mice, with potency similar to that of amphotericin B. KY-62 was well tolerated up to 30 mg/kg of body weight per dose, an amount that would be lethal with amphotericin B. KY-62 was less effective in mice rendered neutropenic with 5-fluorouracil. The addition of flucytosine had little effect. KY-62 may have potential for clinical development. 相似文献
956.
Jane A. Kent-Braun PhD Khema R. Sharma MD Michael W. Weiner MD Robert G. Miller MD 《Muscle & nerve》1994,17(10):1162-1169
We investigated the role of metabolism in muscle fatigue during voluntary exercise in persons with mild multiple sclerosis (MS). Six MS and 8 healthy control subjects performed intermittent, progressive, isometric contractions of the ankle dorsiflexors, during which we measured maximum voluntary force (MVC), inorganic phosphate (Pi), phosphocreatine (PCr), and pH. During exercise. MVC fell sooner in MS, but by the end of exercise the relative decrease in MVC was similar in both groups. In contrast, at the end of exercise Pi/PCr increased to 1.86 ± 0.22 in controls but to only 0.66 ± 0.04 in MS (P < 0.01); likewise, pH was 6.75±0.04 in controls and unchanged (7.06 ± 0.04) in MS (P <0.01). The smaller metabolic change at the same relative exercise intensity suggests a failure of muscle activation that is present even in mild MS. Neurophsyiologic measures of activation indicated some central activation failure and no neuromuscular junction impairment in MS, and suggested that activation failure beyond the muscle membrane(excitation–contraction coupling) may be important in MS. We conclude that metabolic factors do not play a significant role in the development of muscle fatigue during voluntary exercise in mild MS. © 1994 John Wiley & Sons, Inc. 相似文献
957.
Concentric sclerosis (Baló): Morphometric and in situ hybridization study of lesions in six patients
Da-Lin Yao Henry deF. Webster Lynn D. Hudson Michael Brenner Duo-San Liu Alfonso I. Escobar Samuel Komoly 《Annals of neurology》1994,35(1):18-30
Brain tissues from 6 patients with concentric sclerosis (Baló) were examined by in situ hybridization, immunocytochemistry, morphometry, and histological methods. The patients were 24 to 48 years old and had progressive cerebral symptoms and signs that lasted 15 to 100 days. Large demyelinative lesions, most frequent in the frontal white matter, contained alternating bands of demyelinated and partly myelinated white matter that were arranged in concentric or mosaic patterns. In the areas of demyelination, axons were relatively well preserved and there were perivascular inflammatory infiltrates. In 2 specimens, lesions contained regions with the characteristic appearance of actively demyelinating multiple sclerosis plaques. Oligodendroglial densities were highest in normal-appearing white matter, lower in partially myelinated areas, and lowest in demyelinated areas, which also contained many hypertrophic astrocytes closely associated with oligodendroglia. Messenger RNA levels for myelin-related proteins followed the same pattern; they were lowest in demyelinated areas, higher in partially myelinated areas, and highest in normal-appearing white matter beyond lesion margins. Our findings suggest that concentric sclerosis is a variant of multiple sclerosis, that oligodendroglial loss is important in the pathogenesis of demyelination, and that partially myelinated areas probably represent stages of ongoing myelin breakdown rather than remyelination of previously demyelinated areas. 相似文献
958.
959.
960.