全文获取类型
收费全文 | 17552篇 |
免费 | 727篇 |
国内免费 | 75篇 |
专业分类
耳鼻咽喉 | 205篇 |
儿科学 | 310篇 |
妇产科学 | 199篇 |
基础医学 | 2173篇 |
口腔科学 | 546篇 |
临床医学 | 1110篇 |
内科学 | 4012篇 |
皮肤病学 | 229篇 |
神经病学 | 1450篇 |
特种医学 | 770篇 |
外科学 | 3074篇 |
综合类 | 68篇 |
预防医学 | 575篇 |
眼科学 | 222篇 |
药学 | 1172篇 |
中国医学 | 25篇 |
肿瘤学 | 2214篇 |
出版年
2023年 | 90篇 |
2022年 | 167篇 |
2021年 | 263篇 |
2020年 | 160篇 |
2019年 | 184篇 |
2018年 | 279篇 |
2017年 | 186篇 |
2016年 | 243篇 |
2015年 | 246篇 |
2014年 | 366篇 |
2013年 | 433篇 |
2012年 | 710篇 |
2011年 | 716篇 |
2010年 | 470篇 |
2009年 | 415篇 |
2008年 | 712篇 |
2007年 | 718篇 |
2006年 | 764篇 |
2005年 | 770篇 |
2004年 | 750篇 |
2003年 | 742篇 |
2002年 | 755篇 |
2001年 | 779篇 |
2000年 | 784篇 |
1999年 | 707篇 |
1998年 | 245篇 |
1997年 | 188篇 |
1996年 | 188篇 |
1995年 | 137篇 |
1994年 | 108篇 |
1993年 | 108篇 |
1992年 | 468篇 |
1991年 | 413篇 |
1990年 | 379篇 |
1989年 | 463篇 |
1988年 | 376篇 |
1987年 | 343篇 |
1986年 | 360篇 |
1985年 | 346篇 |
1984年 | 250篇 |
1983年 | 166篇 |
1982年 | 76篇 |
1979年 | 147篇 |
1978年 | 101篇 |
1977年 | 87篇 |
1975年 | 80篇 |
1974年 | 76篇 |
1973年 | 76篇 |
1969年 | 92篇 |
1967年 | 87篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Y Kajigaya K Ikuta H Sasaki Y Koiso T Funabiki S Matsuyama 《Journal of Japan Haematological Society》1988,51(5):832-838
72.
73.
74.
The activation of protein kinase C and protein phosphorylation by tumor promoters were examined using quiescent cultures of BALB/3T3 and C3H/10T1/2 cells, because in these cells tumor promoters enhance chemically induced transformation and also induce DNA synthesis and ornithine decarboxylase. The cytosol and membrane fractions were partially purified, and the activity of protein kinase C was assayed. In quiescent cells, protein kinase C activity was found only in the cytosol fraction. Treatment with 100 ng of 12-O-tetradecanoylphorbol-13-acetate or teleocidin B per ml caused rapid translocation of protein kinase C from the cytosol to the membrane fraction. The activity in the cytosol disappeared almost completely after 15 min when the activity in the membrane reached a peak. The membrane activity gradually decreased to the control level after 6 h, while no activity reappeared in the cytosol within 6 h. Under these circumstances, a membrane protein with a molecular weight of 90,000 and pl of 4.0-4.4 (termed p90) was specifically phosphorylated, possibly by the activated protein kinase C, in both cell-free and intact-cell systems. On treatment of quiescent BALB/3T3 cells with 100 ng of 12-O-tetradecanoylphorbol-13-acetate, p90 phosphorylation increased 2-fold in 1 min, reaching a peak in 15 min of 3.4-fold the initial value. The phosphorylation of p90 increased with increase in the concentrations of 12-O-tetradecanoylphorbol-13-acetate between 0.1 and 10 ng/ml and reached a plateau at 10 ng/ml. p90 phosphorylation also occurred on exposure of the cells to non-phorbol ester tumor promoters (mezerein and teleocidin B) and growth factors, such as platelet-derived growth factor and fibroblast growth factor. p90 was not immunoprecipitated by antibody against the insulin receptor. Phosphorylation of p90 occurred at a serine residue. The present study suggests that activation of protein kinase C and phosphorylation of p90 by it are early events leading to tumor promotion. 相似文献
75.
Crystalline lens changes of 17 cases of eye undergoing simple vitrectomy were observed from the post-operative 1st to 21st month. Changes in the crystalline lenses were detected through a slitlamp microscope or by methods of image analysis, the Opacity Lensmeter and the laser scattering spectroscopy. Increases of the scattering light intensity of the anterior and posterior deep cortical layers were observed from the early post-operative stage in 9 cases. Seven cases progressed to nuclear opacification during the observation period, however, one case showed no nuclear changes even at the 12 post-operative month. No relationships were observed between the early cortical changes and surgical invasion, patient age, or cause of vitreous opacification. Quantitative evaluation by image analysis revealed early post-operative crystalline lens changes in cases undergoing vitreous surgery. 相似文献
76.
F Sasaki T Ishizaki H Takahashi S Ameshima T Nakai S Miyabo 《Nihon Kyōbu Shikkan Gakkai zasshi》1992,30(8):1507-1514
To understand the precise mechanism of bronchial hyperresponsiveness in patients with congestive heart failure, we studied the effect of mild pulmonary congestion on bronchial responsiveness to inhaled acetylcholine (ACh) in guinea pigs. We induced mild pulmonary congestion by inflation of a balloon placed in the left atrium, and maintained the left atrial pressure (Pla) at 10 mmHg for 30 minutes with continuous monitoring of lung resistance (RL) and dynamic compliance (Cdyn). Furthermore, we determined the provocative concentration of ACh producing 100% increase in RL (PC100-ACh), before and during balloon inflation. In animals with propranolol pretreatment, but not in animals without propranolol pretreatment, mild pulmonary congestion caused slight increase in RL (N.S.) and significant decrease in Cdyn (p less than 0.01) and PC 100-ACh (p less than 0.01). Cutting of bilateral vagal nerves partially inhibited the decrease of PC100-ACh, but pretreatment with either phenoxybenzamine, indomethacin, AA-861 or OKY-046 had not effect. These results suggest that blockade of beta-adrenergic receptors and the vagal reflex, but not of alpha-adrenergic receptors or arachidonates, contributes to bronchial hyperresponsiveness during acute pulmonary congestion. 相似文献
77.
Livers from fed rats (180-240 g) were perfused noncyclically with a hemoglobin-free medium in vitro to determine whether vasoactive intestinal peptide (VIP) increases hepatic glucose production through a cAMP- or a Ca(2+)-dependent mechanism. Glucose output did not increase, but cAMP increased maximally during 10(-9) M VIP infusion. When VIP was perfused at 10(-8) M or more, glucose output increased dose dependently, whereas cAMP increased only a little during the VIP infusion, but increased greatly after the infusion. When Ca2+ was excluded from the perfusate, glucose output produced by 10(-8)-10(-7) M VIP was only 40% of that observed in the Ca(2+)-containing perfusion, and the increase in cAMP was abolished almost completely. By adding 10(-7) M A23187 for 10 min during the infusion of 10(-9) M VIP, cAMP, which increased with VIP alone, decreased during the A23187 infusion and increased again after the cessation of the A23187 infusion, whereas glucose output increased during the A23187 infusion. These results were similar to those observed with higher concentrations of VIP. When 10(-4) M isobutylmethylxanthine and 10(-8) M VIP were infused concurrently, cAMP increased rapidly during the infusion and decreased after the infusion. In conclusion, 1) glycogenolysis is produced by VIP through a Ca(2+)-dependent mechanism, rather than a cAMP-dependent one; and 2) the restriction of cAMP accumulation during the infusion of high concentrations of VIP is caused by Ca(2+)-induced phosphodiesterase activation. 相似文献
78.
Sho Haneda M.D. Kouhei Fukushima M.D. Yuji Funayama M.D. Chikashi Shibata M.D. Ken-Ichi Takahashi M.D. Hitoshi Ogawa M.D. Munenori Nagao M.D. Kazuhiro Watanabe M.D. Iwao Sasaki M.D. 《Journal of gastrointestinal surgery》2006,10(7):1051-1059
Our previous studies demonstrated that sodium glucose cotransporter 1 (SGLT-1) was induced in the remnant ileum of total colectomized
rats via the action of factors other than hyperaldosteronism. The aim of the present study was to clarify whether fecal stream
is required for the enhancement of SGLT-1-mediated sodium transport. Twenty-seven pairs of ileal tissues were obtained from
the proximal and distal side, respectively, of loop ileostomy after total proctocolectomy. Mucosae were mounted in an Ussing
chamber to evaluate glucose-coupled sodium transport. Levels of SGLT-1 mRNA in proximal and distal mucosae were compared by
Northern blotting. Villous height and crypt depth were measured to test for correlations between mucosal structure and SGLT-1-mediated
sodium transport or mRNA expression levels. Both glucose-coupled sodium transport and expression of SGLT-1 mRNA were significantly
lower in distal mucosae relative to proximal mucosae. In distal mucosae, villous height, but not crypt depth, was significantly
lower than in proximal mucosae, demonstrating a positive correlation between villous height and SGLT-1 function and expression.
Comparative studies of proximal and distal mucosae demonstrated that in addition to hormonal changes, fecal stream is required
for full induction of the sodium transport system (which includes SGLT-1-mediated transport) in the remnant ileum following
total proctocolectomy.
Presented in part at the Forty-Sixth Annual Meeting of The Society for Surgery of the Alimentary Tract, Chicago, Illinois,
May 14–19, 2005 (poster presentation).
This work was supported by Grants-in-Aid for Scientific Research 10557118 and 14657295 from the Ministry of Education, Science
and Culture of Japan to K. Fukushima, and by Kanae Foundation to K. Fukushima. 相似文献
79.
Emiko Ito Fumie Suzuki-ToyotaKiyotaka Toshimori Haruhiko FuwaKazuo Tachibana Masayuki SatakeMakoto Sasaki 《Toxicon》2003,42(7):733-740
Gambierol was isolated from Gambierdiscus toxicus, which causes ciguatera fish poisoning. The acute toxicological effects induced in mice by synthesized gambierol were studied. The lethal doses were about 80 μg/kg by i.p. and i.v., and 150 μg/kg by p.o. The main injury by this toxin was observed in the lung, and secondary in the heart, resulting in systemic congestion. Another toxic effect was seen in the stomach, inducing hypersecretion and ulceration. With survival from the severe stage during the initial 3 h, recovery was favorable, especially after 4 days. Additional effects were not evident during 1-week post-administration observation. 相似文献
80.
A rare case of a dissecting aneurysm of the P3 segment of the right posterior cerebral artery is presented that seems to have occurred in association with mild head injury. The patient was treated surgically because of repeated intramural hemorrhage and enlargement of the aneurysm. Proximal ligation produced thrombosis of the aneurysm without resulting in infarction in the region of the posterior cerebral artery. The mechanisms of the dissection, diagnosis, and treatment are briefly discussed. 相似文献