全文获取类型
收费全文 | 4311篇 |
免费 | 215篇 |
国内免费 | 30篇 |
专业分类
耳鼻咽喉 | 57篇 |
儿科学 | 122篇 |
妇产科学 | 52篇 |
基础医学 | 732篇 |
口腔科学 | 118篇 |
临床医学 | 234篇 |
内科学 | 1041篇 |
皮肤病学 | 60篇 |
神经病学 | 237篇 |
特种医学 | 124篇 |
外科学 | 798篇 |
综合类 | 24篇 |
预防医学 | 155篇 |
眼科学 | 42篇 |
药学 | 311篇 |
中国医学 | 2篇 |
肿瘤学 | 447篇 |
出版年
2023年 | 42篇 |
2022年 | 88篇 |
2021年 | 149篇 |
2020年 | 75篇 |
2019年 | 67篇 |
2018年 | 97篇 |
2017年 | 54篇 |
2016年 | 109篇 |
2015年 | 81篇 |
2014年 | 105篇 |
2013年 | 133篇 |
2012年 | 214篇 |
2011年 | 253篇 |
2010年 | 135篇 |
2009年 | 106篇 |
2008年 | 193篇 |
2007年 | 212篇 |
2006年 | 189篇 |
2005年 | 181篇 |
2004年 | 205篇 |
2003年 | 193篇 |
2002年 | 202篇 |
2001年 | 146篇 |
2000年 | 188篇 |
1999年 | 129篇 |
1998年 | 45篇 |
1997年 | 42篇 |
1996年 | 50篇 |
1995年 | 43篇 |
1994年 | 36篇 |
1993年 | 25篇 |
1992年 | 77篇 |
1991年 | 77篇 |
1990年 | 76篇 |
1989年 | 66篇 |
1988年 | 75篇 |
1987年 | 45篇 |
1986年 | 36篇 |
1985年 | 55篇 |
1984年 | 30篇 |
1983年 | 18篇 |
1982年 | 13篇 |
1979年 | 29篇 |
1976年 | 12篇 |
1974年 | 14篇 |
1971年 | 13篇 |
1970年 | 12篇 |
1969年 | 10篇 |
1968年 | 14篇 |
1967年 | 15篇 |
排序方式: 共有4556条查询结果,搜索用时 31 毫秒
1.
Shohei Takeda Yutaka Inada Yoshiki Ozawa Narue Nakamizo Teruaki Tomaru 《Journal of anesthesia》1995,9(2):176-181
The cardiovascular responses to an infusion of KRN2391, a potassium channel opener, was studied in halothane-anesthetized
dogs. Intravenous administration of KRN2391 at 1.0 and 5.0 μg·kg−1·min−1 for 60 min produced dose-dependent decreases in mean arterial pressure (MAP) and systemic vascular resistance (SVR) associated
with dose-dependent increases in the cardiac index (CI) and stroke volume index (SVI) but was not accompanied by an increase
in heart rate (HR). The maximum decrease in MAP during the infusion of KRN2391 at 1.0 and 5.0 μg·kg−1·min−1 was −13±7% (P<0.01) and −37±10% (P<0.01), respectively. The maximum reduction in SVR after 1.0 and 5.0 μg·kg−1·min−1 was −20±11% (P<0.01) and −60±16% (P<0.01), respectively. A KRN2391 infusion of 1.0 and 5.0 μg·kg−1·min−1 increased Cl a maximum of 11±13% (P<0.05) and 65±33% (P<0.01), respectively. KRN2391 1.0 μg·kg−1·min−1 showed a tendency to increase SVI but this change was not significant, KRN2391 5.0 μg·kg−1·min−1, however, produced a significant increase in SVI. The present results demonstrate that the decrease in MAP and the increases
in CI and SVI caused by KRN2391 are due to a reduction in the afterload. Therefore, we conclude that these cardiovascular
profiles of KRN2391 may be benificial in perioperative uses including the control of systemic blood pressure and the treatment
of hypertension during halothane anesthesia in clinical practice. 相似文献
2.
M. Nakamura Michitaka Ozaki Shohei Fuchinoue Satoshi Teraoka Kazuo Ota 《Transplant international》1997,10(2):89-95
Ischemia-reperfusion injury by free radicals and lipid peroxides is observed in various organs. Ascorbic acid (AsA) or glutathione
(GSH) in various doses (AsA:2, 0.5, 0.1 mmol/kg, GSH:2 mmol/kg) was intraperitoneally administered to male Wistar rats. The
entire small intestines were resected just before ischemia, after ischemia, and after 20 min of reperfusion (n = 7–10 at each time point). At each time point, the specimens were subjected to assays of lipid peroxides, GSH, and glutaminase
activity of the tissues; they were also examined histologically. In the AsA group, the production of lipid peroxides after
reperfusion was significantly suppressed in a dose-dependent manner, and the ratio of oxidized GSH to total GSH was also significantly
low. Tissue glutaminase activity decreased to a lesser extent, and the degree of injury was apparently less marked in the
AsA group. This study indicates that AsA acts as an antioxidant against peroxidative tissue injury, possibly by scavenging
radicals, preserving reduced GSH, and reducing the peroxidative reaction.
Received: 21 June 1996 Received after revision: 8 October 1996 Accepted: 12 November 1996 相似文献
3.
Nine healthy subjects received 0.2 mg of beta-methyldigoxin (beta-MD) orally in the fasting state, 30 minutes after and before a standard breakfast. The time-to-peak serum glycoside concentration was delayed and the peak concentration was lower in the postprandial state compared with the other regimens (P less than .01). The absorption rate constant was significantly reduced when beta-MD was given after a meal (1.55 +/- 1.75 hr-1) than before a meal (5.54 +/- 2.16 hr-1) and in the fasting state (5.22 +/- 3.06 hr-1)(P less than .01). Although the area under the serum glycoside concentration-time curve and the cumulative urinary excretion (CUE) of beta-MD, digoxin, and total drug (beta-MD plus digoxin) was not significantly different between three regimens, the CUE infinity tended to be smaller in the postprandial state compared with before a meal. The results indicate that the timing of drug administration in relation to a meal is an important factor leading to the fluctuations of serum glycoside concentration after oral beta-MD, which might be of some clinical importance. 相似文献
4.
5.
An attempt was made to detect a pancreatic tumor antigen (PTA) in transplantable pancreatic adenocarcinomas induced by N-bis(2-hydroxypropyl)nitrosamine (DHPN) in hamsters. Antibody against antigenic protein was raised by immunizing rabbits with whole homogenate of the tumors transplanted into the back of hamsters. PTA was purified by affinity chromatography and shown to have the physicochemical properties of a glycoprotein with a molecular weight of 800,000, migrating in the beta regions upon agarose gel electrophoresis. Loss of immunological properties was observed after heating at 65 degrees C for 30 min. Enzyme immunoassay revealed that the levels of PTA in the serum and tissue showed a positive correlation with the induction of the presence of tumor, and size of the tumor. It is tentatively suggested that PTA values above 150 ng/ml serum are indicators of tumors, because in normal hamsters the PTA range is from 25 to 130 ng/ml serum. Immunohistochemically, PTA was demonstrated to be localized within the cytoplasm of epithelial tumor cells of well-differentiated tubular adenocarcinomas. 相似文献
6.
Yamamoto Kazuhiko; Nakajima Akira; Eimoto Hiroyuki; Tsutsumi Masahiro; Maruyama Hiroshi; Denda Ayumi; Nii Hiroaki; Mori Yukio; Konishi Yoichi 《Carcinogenesis》1989,10(9):1607-1611
The carcinogenic activity of endogenously synthesized N-nitrosobis(2-hydroxypropyl)amine(BHP) was investigated in male Wistar rats administered bis(2-hydroxypropyl)amine(BHPA) mixed in powder diet at a concentration of 1%, and sodiumnitrite (SN) dissolved in distilled water at concentrationsof 0.15 and 0.3%, for 94 weeks. Urinary excretion of BHP wasdetected in rats given 1% BHPA and 0.3% SN but not in the groupsreceiving either of these precursors alone. Nasal cavity, lung,esophagus, liver and urinary bladder tumors were found in animalstreated with combinations of 1% BHPA and 0.15 or 0.3% SN, suggestingthat the target organs of the endogenously synthesized BHP aresimilar to those affected when the carcinogen is administeredexogenously. The incidences of nasal cavity and lung tumorsreached 74 and 58% in rats given 1% BHPA and 0.3% SN, respectively.Tumors at sites other than target organs were only found atlevels similar to those previously reported for spontaneoustumors in male Wistars. The present results clearly indicatedthe tumor inducibility of a nhrosatable amine, BHA, throughan endogenous nitrosation by feeding to rats in conjunctionwith nitrite, and provide further suggestive evidence that endogenousnitrosations of environmental nitrosatable amines can be a potentialrisk factor in human cancer development. 相似文献
7.
Y Tsutsumi X Jie K Ihara A Nomura S Kanemitsu H Takada T Hara 《Diabetic medicine》2006,23(10):1145-1150
AIMS: To investigate the contribution of regulatory T cells and co-stimulatory molecules in CD4(+) T cells to the development of Type 1 diabetes (T1D). METHODS: Twelve patients with T1D, nine patients with systemic lupus erythematosus (SLE), and 12 age-matched healthy control subjects participated. We analysed the proportions of CD25(+)CD4(+) T cells and natural killer T cells (NKT cells), and the expression levels of Foxp3, CTLA-4, CD28, ICOS, PD-1 and BTLA in peripheral blood mononuclear cells and purified CD4(+) T cells. RESULTS: There were no significant differences in the proportions of CD25(+) CD4(+) T cells or NKT cells among the three groups. PD-1 expression levels of peripheral CD4(+) T cells from T1D patients were significantly lower than those from healthy control subjects (P = 0.00066). In contrast, PD-1 expression levels were similar in SLE patients and healthy control subjects. The expression levels of Foxp3, CTLA-4, CD28, ICOS and BTLA were similar in the three groups. CONCLUSIONS: Decreased expression of the PD-1 gene in CD4(+) T cells may contribute to the development and/or maintenance of autoimmune T1D. As the population studied was small and heterogeneous, further studies are required to confirm the findings. 相似文献
8.
Yoshio Mitsuyama M.D Hiroyuki Hashiguchi M.D Toshihiko Murayama M.D Masashi Koono M.D Shohei Nishi M.D 《Psychiatry and clinical neurosciences》1992,46(3):741-748
Abstract: A 78-year-old male with renal carcinoma was treated with a high dose infusion of interferon-alpha (IFN-alpha) for eight months. The patient had evidence of organlc brain syndrome such 88 : dysfunction of memory, slowing of behavior, and development of mental confusion that appeared eight months after the treatment. MRI at the time of mental confusion revealed difise white matter lesions. Neuropathologic findings were compatible to Binswanger's disease and Senile Dementia of Alzheimer Type (SDAT), Preexisting neurologic abnormalities including intracerebral arteriosclerosis and cerebral atrophy may increase susceptibility to unacceptably severe IFN neurotoxicity. 相似文献
9.
Koichiro Uto Kazuya Yamamoto Shohei Hirase Takao Aoyagi 《Journal of controlled release》2006,110(2):408-413
The objective of this study is to develop a sensitive temperature-responsive material that would function near body temperature. To achieve this purpose, we compounded 2-branched and 4-branched poly(epsilon-caprolactone) macromonomers to modulate the transition temperatures of the resulting cross-linked materials. The temperature-responsive properties were studied using differential scanning calorimetry and X-ray diffraction measurements. As a result, the mixing ratios of each macromonomer or the total macromonomer concentrations were very dominant in modulating the transition temperatures. The materials could successfully control the permeation of the model drug, prednisolone, near body temperature. 相似文献
10.
Y. Tsutsumi T. Kihira S. Tsunoda T. Kanamori S. Nakagawa T. Mayumi 《British journal of cancer》1995,71(5):963-968
This study was conducted to increase the anti-tumour potency and reduce the toxic side-effects of tumour necrosis factor alpha (TNF-alpha). Natural human TNF-alpha was chemically conjugated with monomethoxy polyethylene glycol (PEG) using succinimidyl coupling of lysine amino groups of TNF-alpha. The number-average molecular weight of PEG-modified TNF-alpha (PEG-TNF-alpha) increased with an increase in the reaction time and the initial molar ratio of PEG relative to TNF-alpha. The resulting modified TNF-alpha was separated into fractions of various molecular weights. The specific activity of separated PEG-TNF-alpha s relative to that of native TNF-alpha gradually decreased with an increase in the degree of PEG modification, but the plasma half-life was drastically increased with the increase in molecular weight of modified TNF-alpha. PEG-TNF-alpha s, in which 29% and 56% of lysine residues were coupled to PEG, had anti-tumour activity approximately 4 and 100 times greater than unmodified TNF-alpha in the murine Meth-A fibrosarcoma model. Extensive PEG modification did not increase its in vivo activity. A high dose of unmodified TNF-alpha induced toxic side-effects, but these were not observed with the modified TNF-alpha s. Optimal PEG modification of TNF-alpha markedly increased its bioavailability and may facilitate its potential anti-tumour therapeutic use. 相似文献