全文获取类型
收费全文 | 2730420篇 |
免费 | 211864篇 |
国内免费 | 28905篇 |
专业分类
耳鼻咽喉 | 34685篇 |
儿科学 | 83317篇 |
妇产科学 | 72926篇 |
基础医学 | 386427篇 |
口腔科学 | 71435篇 |
临床医学 | 271714篇 |
内科学 | 518401篇 |
皮肤病学 | 55570篇 |
神经病学 | 218017篇 |
特种医学 | 101516篇 |
外国民族医学 | 1002篇 |
外科学 | 378705篇 |
综合类 | 104319篇 |
现状与发展 | 80篇 |
一般理论 | 914篇 |
预防医学 | 220199篇 |
眼科学 | 63535篇 |
药学 | 205933篇 |
341篇 | |
中国医学 | 22794篇 |
肿瘤学 | 159359篇 |
出版年
2021年 | 34747篇 |
2020年 | 23650篇 |
2019年 | 30532篇 |
2018年 | 39085篇 |
2017年 | 30926篇 |
2016年 | 32708篇 |
2015年 | 40613篇 |
2014年 | 54716篇 |
2013年 | 72161篇 |
2012年 | 99916篇 |
2011年 | 107722篇 |
2010年 | 63866篇 |
2009年 | 57502篇 |
2008年 | 92596篇 |
2007年 | 96999篇 |
2006年 | 97853篇 |
2005年 | 95083篇 |
2004年 | 85432篇 |
2003年 | 81236篇 |
2002年 | 77524篇 |
2001年 | 119407篇 |
2000年 | 123473篇 |
1999年 | 105137篇 |
1998年 | 32958篇 |
1997年 | 30525篇 |
1996年 | 29293篇 |
1995年 | 27790篇 |
1994年 | 25227篇 |
1993年 | 22741篇 |
1992年 | 77940篇 |
1991年 | 75252篇 |
1990年 | 72768篇 |
1989年 | 68966篇 |
1988年 | 63658篇 |
1987年 | 61803篇 |
1986年 | 58197篇 |
1985年 | 55394篇 |
1984年 | 41916篇 |
1983年 | 35595篇 |
1982年 | 21690篇 |
1979年 | 37591篇 |
1978年 | 26571篇 |
1977年 | 22059篇 |
1976年 | 21183篇 |
1975年 | 21707篇 |
1974年 | 26423篇 |
1973年 | 25781篇 |
1972年 | 23822篇 |
1971年 | 21985篇 |
1970年 | 20711篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
Mitogenic and protein synthetic activity of tissue repair cells: control by the postsurgical macrophage 总被引:3,自引:0,他引:3
M Fukasawa J D Campeau D L Yanagihara K E Rodgers G S Dizerega 《Journal of investigative surgery》1989,2(2):169-180
It is well known that fibroblasts are a main source of extracellular matrix synthesis necessary for tissue repair. In addition, macrophages secrete products that are known to modulate synthesis of extracellular matrix. Accordingly, we studied the incorporation of [3H]thymidine, [3H]proline, and [35S]sulfate into macromolecules produced by fibroblasts recovered from the site of peritoneal tissue repair cultured with and without spent media from postsurgical peritoneal macrophages. Rabbits underwent resection and reanastomosis of their small intestines. Peritoneal exudative cells (PEC) were then collected on postsurgical day 5 and day 10 as well as from nonsurgical controls, separated by discontinuous Percoll gradient centrifugation, and cultured for 48 h. A second group of rabbits underwent peritoneal wall abrasion from which fibroblast tissue repair cells (TRC) were collected from the site of injury at postsurgical day 7 and maintained in culture for varying times. Incorporation of radiolabeled precursors into DNA, collagen, and sulfated proteoglycans was determined. Incorporation of [3H]thymidine and [3H]proline into untreated TRC gradually decreased with culture duration. Conversely, [35S]sulfate incorporation gradually increased during prolonged culture. Macrophage spent media increased the levels of [3H]thymidine incorporation by the TRC. [3H]Proline and [35S]sulfate incorporation into TRC were also stimulated by macrophage spent media. However, this stimulation may be due to the enhanced proliferation of TRC by macrophage spent media. In conclusion, tissue repair fibroblasts are activated for postsurgical repair at the site of injury by many factors including secretory products from postsurgical macrophages. 相似文献
993.
Characterization of unique ADTN-catecholamine binding sites in the iris root-ciliary body of rabbits
A binding site for tritiated 2-amino-6, 7-dihydroxy-1, 2,3,4-tetrahydronaphthalene (ADTN) has been partially characterized in the rabbit iris root-ciliary body. Binding of ADTN is proportional to protein content and requires at least 60 minutes to reach equilibrium. Binding is saturable, with a Kd of 27 +/- 1 nM and a Bmax of 2.1 +/- .3 pmol/mg protein (mean +/- SEM). Dopamine competes for this site with a Ki of 100 nM and apomorphine with a Ki of 180 nM. This site is not blocked by L-timolol, phenoxybenzamine, or by several DA1 and DA2 antagonists. It appears to be a new type of catecholamine binding site, of a type not observed outside the anterior eye. It is possible that some of the effects of dopamine on intraocular pressure are mediated through this binding site. 相似文献
994.
In open chest dogs myocardial ischemia was induced by formation of an occlusive thrombus in the left anterior circumflex artery (LCX). Reperfusion of the LCX was achieved by infusion of the fibrin specific recombinant single-chain urokinase-type plasminogen activator (r-scu-PA). The myocardial salvage by r-scu-PA alone and in combination with the epoprostenol (prostacyclin) analog taprostene (CG 4203) was compared. There were four experimental groups: group 1 (n = 4) did not receive any treatment after LCX thrombosis; in group 2 (n = 9) at 100 min after LCX thrombosis r-scu-PA (20 micrograms.kg-1.min-1 i.v. for 30 min) was infused; in groups 3 and 4 treatment with taprostene started concomitantly with r-scu-PA infusion. The taprostene infusions lasted for 120 min and the doses were 0.1 microgram.kg-1.min-1 in group 3 (n = 6) and 0.215 microgram.kg-1.min-1 in group 4 (n = 6). Time to r-scu-PA-induced recanalisation ranged from 18-22 min with no significant difference between groups 2-4. Percent of left ventricle at risk did not differ between the groups. Infarct size as percent of the risk zone was 48.3 +/- 7.7 in group 1, 25.3 +/- 3.7 in group 2, 21.3 +/- 6.5 in group 3 and 17.1 +/- 3.5 in group 4 (p less than 0.05 groups 2-4 vs group 1). Incidence of ectopic beats increased after r-scu-PA-induced reperfusion in groups 2-4, but was significantly reduced by taprostene.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
995.
The extent to which repeated administration produces tolerance to nicotine-induced increases in dopamine transmission in the nucleus accumbens was investigated in rats. In vivo microdialysis was used to sample extracellular dopamine and metabolites after a nicotine challenge (0.35 mg/kg) in (1) naive rats, (2) acutely pretreated rats (1 prior nicotine injection), and (3) chronically pretreated rats (12-15 prior daily nicotine injections, 0.35 mg/kg per injection). Nicotine increased extracellular DA and its metabolites, and these increases were not significantly altered by either acute or chronic prior exposure to the drug. The failure to find evidence of tolerance is compatible with the hypothesis that the mesolimbic dopaminergic system is a substrate for the reinforcing properties of chronically administered nicotine. 相似文献
996.
997.
998.
999.
Single course versus maintenance bacillus Calmette-Guerin therapy for superficial bladder tumors: a prospective, randomized trial 总被引:1,自引:0,他引:1
M A Hudson T L Ratliff D P Gillen E O Haaff S M Dresner W J Catalona 《The Journal of urology》1987,138(2):295-298
A total of 42 patients with recurrent superficial bladder tumors or carcinoma in situ entered a prospective, randomized trial to compare the efficacy of bacillus Calmette-Guerin therapy with and without quarterly maintenance instillations of bacillus Calmette-Guerin. Maintenance therapy did not reduce further bladder tumor recurrence rates or the interval to recurrence in patients who responded to the initial course of therapy. However, prolongation of toxicity was observed with maintenance bacillus Calmette-Guerin therapy. 相似文献
1000.
Kojic amine [2-(aminomethyl)-5-hydroxy-4H-pyran-4-one], an analogue of gamma-aminobutyric acid (GABA), produced dose-related, but short-lived, antinociceptive activity in the 48 degrees C [ED50 = 9.2 (8.2-10.3) mg/kg i.p.] and 55 degrees C [ED50 = 13.8 (12.2-15.7) mg/kg i.p.] hot-plate tests in the mouse. The antinociceptive activity of kojic amine at 48 degrees C was found to be insensitive to bicuculline (1.0 mg/kg i.p.) and picrotoxin (0.5 mg/kg i.p.). At this temperature, antinociception was distinctly separate from the impairment of motor function (measured by a rotorod assay) and was not significantly affected by prior treatment with the cholinergic antagonist, atropine sulfate (10.0 mg/kg i.p.). However, at 55 degrees C, the antinociceptive effect of a large dose (20 mg/kg i.p.) of kojic amine was significantly attenuated by similar pretreatment with atropine sulfate, but not by the peripheral cholinergic antagonist, atropine methylnitrate (10.0 mg/kg i.p.). Kojic amine exhibited no significant interaction with haloperidol (0.5 mg/kg i.p.) at this temperature. In animals made tolerant to morphine, THIP or baclofen, there was analgesic cross-tolerance between kojic amine, morphine and baclofen but not between kojic amine and THIP. It is suggested that kojic amine-induced antinociception is similar to that produced by both THIP and baclofen. Thus, kojic amine represents a unique tool with which to study GABA-ergic antinociceptive processes. 相似文献