全文获取类型
收费全文 | 7440篇 |
免费 | 659篇 |
国内免费 | 220篇 |
专业分类
耳鼻咽喉 | 22篇 |
儿科学 | 62篇 |
妇产科学 | 52篇 |
基础医学 | 381篇 |
口腔科学 | 369篇 |
临床医学 | 1204篇 |
内科学 | 767篇 |
皮肤病学 | 126篇 |
神经病学 | 243篇 |
特种医学 | 677篇 |
外科学 | 389篇 |
综合类 | 943篇 |
现状与发展 | 1篇 |
预防医学 | 536篇 |
眼科学 | 91篇 |
药学 | 1823篇 |
2篇 | |
中国医学 | 211篇 |
肿瘤学 | 420篇 |
出版年
2024年 | 20篇 |
2023年 | 97篇 |
2022年 | 169篇 |
2021年 | 249篇 |
2020年 | 203篇 |
2019年 | 193篇 |
2018年 | 191篇 |
2017年 | 229篇 |
2016年 | 231篇 |
2015年 | 281篇 |
2014年 | 492篇 |
2013年 | 573篇 |
2012年 | 477篇 |
2011年 | 432篇 |
2010年 | 344篇 |
2009年 | 345篇 |
2008年 | 345篇 |
2007年 | 395篇 |
2006年 | 401篇 |
2005年 | 258篇 |
2004年 | 231篇 |
2003年 | 250篇 |
2002年 | 221篇 |
2001年 | 173篇 |
2000年 | 126篇 |
1999年 | 157篇 |
1998年 | 148篇 |
1997年 | 156篇 |
1996年 | 109篇 |
1995年 | 84篇 |
1994年 | 96篇 |
1993年 | 75篇 |
1992年 | 79篇 |
1991年 | 63篇 |
1990年 | 57篇 |
1989年 | 58篇 |
1988年 | 50篇 |
1987年 | 44篇 |
1986年 | 40篇 |
1985年 | 44篇 |
1984年 | 23篇 |
1983年 | 13篇 |
1982年 | 26篇 |
1981年 | 14篇 |
1980年 | 12篇 |
1979年 | 7篇 |
1978年 | 11篇 |
1977年 | 13篇 |
1976年 | 8篇 |
1973年 | 3篇 |
排序方式: 共有8319条查询结果,搜索用时 0 毫秒
1.
本实验制作不同程度心肌缺血的动物模型,以声处理5%人血白蛋白为超声造影剂进行心肌灌注造影,探讨MCE时间-强度曲线各指标与心肌缺血程度间的关系。结果表明:心肌显影的峰值强度和曲线下面积均与缺血程度呈显著负相关(相关系数分别为r=-0.98,P值<0.005;r=-0.94,P值<0.05),且能区分轻度、中度和重度三种程度的心肌缺血;而三项时间指标与心肌缺血程度间未发现显著性差异。本实验的初步结果表明,MCE是一项活体评估局部心肌血流灌注的有效方法。 相似文献
2.
Irfan Soykan Irene Sarosiek Jeannie Shifflett George F. Wooten Dr. Richard W. McCallum 《Movement disorders》1997,12(6):952-957
This study investigated whether domperidone could improve gastrointestinal symptoms in patients with Parkinson's disease who were receiving levodopa therapy. A total of 11 patients were studied. Following a baseline gastric emptying test, patients were treated with a starting dose of domperidone 20 mg p.o. q.i.d. A follow-up gastric emptying test was repeated at least 4 months after starting domperidone therapy. At the beginning and at each 3-month follow-up visit, symptoms of nausea, vomiting, anorexia, abdominal bloating, heartburn, regurgitation, dysphagia, and constipation were evaluated and scored on a scale of 0–3. The overall mean follow-up period was 3 years. Compared with their baseline evaluation, patients experienced a significant improvement in all symptoms (p < 0.05) except dysphagia and constipation. Gastric emptying of an isotope-labeled solid meal was significantly faster, with a baseline result of 60.2 ± 6.4% retention of isotope 2 h after the meal compared with 37.0 ± 2.2% retention during domperidone therapy (p < 0.05). Patients' global assessment of Parkinson's disease remained stable or improved. Serum prolactin was elevated in all patients after domperidone therapy (p < 0.05). Domperidone therapy significantly reduces upper gastrointestinal symptoms and accelerates gastric emptying of a solid meal, but does not interfere with response to antiparkinsonism treatment. 相似文献
3.
本文应用“冷沉淀”法制备纤维组织粘合剂。对纤维组织粘合剂中主要成份和含量进行了测定,并测定了主要理化性质,建立了动物实验模型,观察了实验兔对纤维粘合剂的反应。 相似文献
4.
Several alkyl[3-(2-chloroethyl)ureido] (CEU) benzene derivatives were prepared as potential anticancer agents. These new compounds were readily prepared in good yields by addition of anilines to 2-chloroethylisocyanate. Their cytotoxic activity was evaluated on human breast cancer (MDA-MB-231), human colon adenocarcinoma (LoVo) and mouse lymphocytic leukemia (P388D1) tumor cell lines. Several new CEUs were significantly more cytotoxic than the nitrogen mustard chlorambucil. The biological activity of these aromatic urea derivatives seems to be related to the nature and position of the alkyl substituents on the aromatic ring. Substitution by branched alkyl groups on position 4 of the aromatic ring led to cytotoxic molecules which are up to 5 times more potent than the standard chlorambucil. 相似文献
5.
防晒制剂皮肤安全性的实验研究 总被引:2,自引:0,他引:2
目的 :探讨同一系列不同SPF(sunprotectionfactor)防晒制剂对皮肤的安全性 ,筛选安全有效的防晒制剂配方。方法 :选用白化豚鼠背部去毛 ,分别涂抹SPF值为 15、2 8、30 +三种防晒制剂 ,以UV光源照射 ,波长为 32 0~4 0 0nm ,强度为 ( 16 8± 2 )mW/cm2 。结果 :三种不同SPF防晒制品对实验动物皮肤各时相点反应积分为 ,SPF15组为0 ;SPF2 8组为 1;SPF30 +组为 3。结论 :三种不同SPF值产品对皮肤的光毒性有一定差异 ,提示SPF值在 2 8以内的防晒制剂皮肤安全性较好 ,SPF30 +的防晒制剂对皮肤有一定光毒刺激反应。 相似文献
6.
Yoshihiro Sei Taizo Hamaguchi Junya Ninomiya Atsuhiro Nakabayashi Iwao Takiuchi 《The Journal of dermatology》1994,21(5):334-340
In order to elucidate the effectiveness of anti-mycotics in treating seborrhoeic dermatitis, an attempt was made to isolate Malassezia from seborrhoeic lesions of patients of seborrhoeic dermatitis. The results revealed that, in male patients, 46/49 cases were positive for Malassezia furfur on the face and 30/48 cases were positive for M. furfur on the scalp. In female patients, 7/13 cases were positive for M. furfur on the face, and 6/17 cases were positive for M. furfur on the scalp. Anti-mycotic agents were excellent in 50% and good in 31% of the spore-positive cases, yielding an overall efficacy rate of 81%. In contrast, the treatment of the face with vehicle alone showed only one excellent result out of 8 cases. Although clinical improvement was rapid on the side treated with a topical corticosteroid in the half-side-test, numerous fungal elements remained. While the improvement with anti-mycotic agents was slower than that with the corticosteroid, clinical improvement became evident by the third week of administration and fungal elements disappeared. 相似文献
7.
Flecainide 总被引:1,自引:0,他引:1
RODNEY H. FALK M.D. RICHARD I. FOGEL M.D. 《Journal of cardiovascular electrophysiology》1994,5(11):964-981
Flecainide. Flecainide is a Class IC antiarrhythmic agent whose primary electrophysiologic effect is a slowing of conduction in a wide range of cardiac tissues. It is well absorbed and effective in suppressing isolated premature ventricular contractions (PVCs) or nonsustained ventricular arrhythmia but has only a modest efficacy when electrophysiologic testing is used as an endpoint. Us adverse effect on mortality in the CAST trial suggested a propensity to proarrhythmia-a phenomenon to which the Class IC agents appear particularly prone. Despite the applicability of the CAST study only to patients with a prior myocardial infarction, there has been a shift away from flecainide in ventricular arrhythmia, but the low noncardiac side effect profile of the agent allows for its continued use in a wide variety of supraventricular arrhythmias. ( J Cardiovasc Electrophysiol, Vol. 5, pp. 964–981. November 1994 ) 相似文献
8.
A. Tchelet T. Vogel D. Helman R. Guy C. Neospouolus V. Goffin J. Djiane A. Gertler 《Molecular and cellular endocrinology》1997,130(1-2):141-152
A new analogue of recombinant human growth hormone (hGH), hGH des(1–6,14) was expressed in Escherichia coli, refolded and purified to homogeneity. The mutation decreased the hormone's ability to bind lactogenic and somatogenic receptors through its site 1, and almost completely abolished its ability to bind these receptors through site 2, as evidenced by both binding and gel-filtration experiments. More specifically, the binding to prolactin receptors (PRLRs) from various species or their soluble recombinant extracellular domains (ECDs) was decreased 1.5–4-fold, whereas the binding to hGH receptor (hGHR) was decreased 10–85-fold. These changes caused an almost total loss of hormone agonistic activity in several in vitro bioassays and subsequently, the hGH des(1–6,14) analogue acquired antagonistic properties. This antagonistic activity was dependent upon modification of site 1. In those cases in which the binding was reduced only slightly, e.g. binding to rabbit PRLRs, hGH des(1–6,14) acted as a strong antagonist, whereas in others in which the binding of site 1 was reduced to a higher degree, such as other PRLRs and, in particular, hGHR, the antagonistic activity was correspondingly weaker. Circular dichroism spectra of the analogue suggested that these changes do not result from a decrease in overall -helix content, but rather from minor local structural modifications at the N-terminus. 相似文献
9.
目的:寻找适合于临床PCR检测结核杆菌DNA简单、快速、有效、经济的细菌裂解方法。方法:采用11种细菌裂解剂对相同数量的结核分枝杆菌进行裂解,裂解上清液直接用于PCR扩增,结果:1%TritonX-100,1%NP40,1%Teween20、和1%OP四种裂解剂的裂解液可直接扩增出结核分枝杆菌DNA;SDS,NaOH,十二烷基肌酸钠等裂解剂的裂解液直接用于PCR扩增均为阴性。结论:1%的Tritonx-100,NP40、Teween20和乳化剂OP裂解细菌效果好,又不抑制PCR反应,适合于作为临床PCR检测结核杆菌的裂解剂。 相似文献
10.
《Journal of labelled compounds & radiopharmaceuticals》2003,46(7):605-611
JTT‐501 specifically labelled with 13C was obtained via a four‐step synthesis at an isotopic enrichment level of 99% and in 14% overall chemical yield starting from 4‐hydroxy‐[ring‐U‐13C6]benzaldehyde (3) . The hydrogenation of [13C6]JTT‐501 over Pd/C gave [13C6]JTP‐20604 in 90% chemical yield. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献