全文获取类型
收费全文 | 8926篇 |
免费 | 499篇 |
国内免费 | 354篇 |
专业分类
耳鼻咽喉 | 39篇 |
儿科学 | 93篇 |
妇产科学 | 28篇 |
基础医学 | 1311篇 |
口腔科学 | 629篇 |
临床医学 | 514篇 |
内科学 | 969篇 |
皮肤病学 | 161篇 |
神经病学 | 514篇 |
特种医学 | 106篇 |
外科学 | 886篇 |
综合类 | 791篇 |
现状与发展 | 2篇 |
预防医学 | 398篇 |
眼科学 | 55篇 |
药学 | 2548篇 |
5篇 | |
中国医学 | 487篇 |
肿瘤学 | 243篇 |
出版年
2023年 | 63篇 |
2022年 | 136篇 |
2021年 | 260篇 |
2020年 | 200篇 |
2019年 | 222篇 |
2018年 | 267篇 |
2017年 | 222篇 |
2016年 | 233篇 |
2015年 | 205篇 |
2014年 | 575篇 |
2013年 | 612篇 |
2012年 | 501篇 |
2011年 | 606篇 |
2010年 | 463篇 |
2009年 | 415篇 |
2008年 | 417篇 |
2007年 | 377篇 |
2006年 | 381篇 |
2005年 | 316篇 |
2004年 | 316篇 |
2003年 | 288篇 |
2002年 | 246篇 |
2001年 | 176篇 |
2000年 | 136篇 |
1999年 | 146篇 |
1998年 | 150篇 |
1997年 | 148篇 |
1996年 | 134篇 |
1995年 | 105篇 |
1994年 | 100篇 |
1993年 | 90篇 |
1992年 | 99篇 |
1991年 | 76篇 |
1990年 | 80篇 |
1989年 | 75篇 |
1988年 | 55篇 |
1987年 | 57篇 |
1986年 | 54篇 |
1985年 | 110篇 |
1984年 | 119篇 |
1983年 | 96篇 |
1982年 | 98篇 |
1981年 | 70篇 |
1980年 | 65篇 |
1979年 | 61篇 |
1978年 | 39篇 |
1977年 | 30篇 |
1976年 | 27篇 |
1975年 | 16篇 |
1973年 | 18篇 |
排序方式: 共有9779条查询结果,搜索用时 15 毫秒
21.
Zheng Qi-xin Zhu Tong-bai Du Jing-yuan Hong Guang-xiang Li Shi-pu Yan Yun-hua Zhang En-dang 《华中科技大学学报(医学英德文版)》1992,12(3):173-178
Summary The authors have prepared the artificial bone of porous tricalcium phosphate ceramics according to an appropriate formula
and manufacturing technology. Physical and chemical testing shows that it possesses several distinguishing features: the communicating
pores and macro/micropores; mean pore size, 380 μm (from 240 μm to 510 μm); porosity, 46.4 %; and compressive strength, 97.4
kg/cm2. It consists of CaO (49.09 %) and P2O5 (48.84 %). The testing of its biocompatibility shows that it is devoid of systemic or local toxicity, and free of irritation
or foreign body response in tissues, and it does not result in hemolysis or mutation. The new bone readily grows into its
pores with direct contact to the implanted material. 11 cases of bone defects were treated with this artificial bone with
satisfactory results. 相似文献
22.
为证明癫痫发作早期一氧化氮(NO)抗发作效应,用NO合酶(NOS)抑制剂L-硝基精氨酸甲酯(L-NAME)对大鼠红藻氨酸(KA)诱导性发作进行干预,同时用分光光度法检测海马结构中NOS活性的早期变化。发现KA发作10min、30min组海马结构中NOS活性明显升高,而KA注射前30min给予L-NAME可显著抑制NOS活性的升高,这种抑制效应与大鼠KA发作中湿狗样摇动(WDS)的提早出现和发生次数增多显著相关。结果提示在KA诱导大鼠发作早期内源性NO具有明显的抗发作效用。 相似文献
23.
24.
Abstract Nitric oxide (NO) plays an important physiological role in regulating gastrointestinal motility. Involvement of endogenous NO was evaluated in the response to non-adrenergic, non-cholinergic (NANC) nerve stimulation of the dog sphincter muscle of Oddi. Transmural electrical stimulation (TES), nicotine (10?5M) and K+ (10 mM) produced only a relaxation in the sphincter muscle strips contracted with substance P, which was not potentiated by atropine. The TES-induced relaxation was abolished by tetrodotoxin (3 times 10?7 M) and oxyhaemoglobin (1.6 times 10?5 M), but not affected by atropine (10?7 M), propranolol (10?7 M), phentolamine (10?7 M), indomethacin (10?6 M), chole-cystokinin (CCK, 10?8 M) and vasoactive intestinal polypeptide (VIP, 10?8 M). The relaxation was also abolished by treatment with NG-nitro-L-arginine (L-NA, 10?5 M), an NO synthase inhibitor. Nicotine produced a transient relaxation, which was abolished by tetrodotoxin, hexamethonium (10?5 M) and L-NA, but not affected by atropine and NG-nitro-D-arginine (D-NA, 10?5 M). The addition of K+ elicited a transient relaxation, which was abolished by tetrodotoxin and L-NA. The inhibitory effects of L-NA were antagonized by L-arginine (10?3 M). The presence of neurons containing nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase was histochemically demonstrated in the sphincter of Oddi. These findings may indicate that TES, nicotine and K+ liberate NO from NANC inhibitory nerve which is involved in the relaxation of the dog sphincter of Oddi. The muscular tone does not seem to be regulated by cholinergic nerves under the experimental conditions used. 相似文献
25.
采用薄层扫描法对复脉定冲剂中远志有效成分3,4,5-三甲氧基反式肉桂酸乙酯的含量进行测定。方法简单、快速,结果可靠,可作为该制剂的质控标准。 相似文献
26.
27.
Stuart M. Lichtman Abraham Mittelman Daniel R. Budman Carmelo A. Puccio Hoo G. Chun Steven L. Allen Tauseef Ahmed Zalmen A. Arlin 《Leukemia & lymphoma》1991,6(1):61-63
A phase II trial of fludarabine phosphate using a bolus and continuous infusion regimen in previously treated multiple myeloma was performed. No responses were observed in eleven patients. There was no significant non-hematologic toxicity noted. Fludarabine phosphate is inactive in multiple myeloma using this schedule. 相似文献
28.
对TOCP染毒母鸡进行为期7周的神经电生理监测,结果表明,TOCP主要影响远端周围神经,导致坐骨神经远端MCV和SCV减慢及腓肠肌EMG失神经样改变,而胫后神经H反射及重复电刺激无明显异常。 相似文献
29.
维胺酯-β-环糊精包合物的研究 总被引:6,自引:0,他引:6
应用3因素8水平的均匀设计方法,优化出维胺酯-β-环糊精包合物最佳制备条件,所得包合物的包合率为99.3%,其表观稳定常数为1394M-1. 相似文献
30.
Purpose. To obtained rate constants from weight-averaged (Mw) or z-averaged (Mz) molecular weights for polymers of Schule-Flory distribution and undergoing random scission. These constants were compared with those obtained by parallel 1HNMR studies.
Methods. The hydrolysis of two poly(ortho ester)s were followed by 1HNMR and gel permeation chromatography (GPC).
Results. Equations to convert number-averaged (Mn), Mw and Mz into fraction of backbone remaining (fc) were derived. First-order hydrolytic rate constants of two poly(ortho ester)s; DETOSU-HD and DETOSU-CDM were calculated using these relationships. The rate constants calculated from 1HNMR, Mz and Mw were 0.215, 0.218 and 0.182 hr–1, respectively, for DETOSU-CDM and 0.152, 0.086 and 0.038 hr–l for DETOSU-HD. The large discrepancy in the rates determined by 1HNMR and GPC in the latter case was attributed to that the detector response (refractive index) of the monomers was lower than that of the high molecular weight polymer. The difference is small in the case of DETOSU-CDM, and the rates calculated from GPC data were comparable or nearly identical to that obtained from 1HNMR data.
Conclusions. Although GPC can yield rapid and valuable kinetic data for the degradation of biodegradable polymers, the system, however, must be carefully calibrated to account for the variations in Mark-Houwink coefficients and in the response of the mass detector between the high and low MW polymers. 相似文献