全文获取类型
收费全文 | 37834篇 |
免费 | 2136篇 |
国内免费 | 694篇 |
专业分类
耳鼻咽喉 | 176篇 |
儿科学 | 728篇 |
妇产科学 | 444篇 |
基础医学 | 3922篇 |
口腔科学 | 269篇 |
临床医学 | 4985篇 |
内科学 | 4989篇 |
皮肤病学 | 410篇 |
神经病学 | 1455篇 |
特种医学 | 1356篇 |
外科学 | 3565篇 |
综合类 | 6814篇 |
预防医学 | 4518篇 |
眼科学 | 179篇 |
药学 | 3991篇 |
24篇 | |
中国医学 | 2299篇 |
肿瘤学 | 540篇 |
出版年
2024年 | 70篇 |
2023年 | 403篇 |
2022年 | 916篇 |
2021年 | 1325篇 |
2020年 | 1229篇 |
2019年 | 902篇 |
2018年 | 928篇 |
2017年 | 992篇 |
2016年 | 1097篇 |
2015年 | 1132篇 |
2014年 | 2493篇 |
2013年 | 2562篇 |
2012年 | 2335篇 |
2011年 | 2485篇 |
2010年 | 1946篇 |
2009年 | 1862篇 |
2008年 | 1765篇 |
2007年 | 1742篇 |
2006年 | 1675篇 |
2005年 | 1384篇 |
2004年 | 1202篇 |
2003年 | 1079篇 |
2002年 | 908篇 |
2001年 | 779篇 |
2000年 | 770篇 |
1999年 | 618篇 |
1998年 | 523篇 |
1997年 | 536篇 |
1996年 | 440篇 |
1995年 | 438篇 |
1994年 | 381篇 |
1993年 | 374篇 |
1992年 | 297篇 |
1991年 | 273篇 |
1990年 | 260篇 |
1989年 | 213篇 |
1988年 | 235篇 |
1987年 | 220篇 |
1986年 | 170篇 |
1985年 | 191篇 |
1984年 | 216篇 |
1983年 | 135篇 |
1982年 | 170篇 |
1981年 | 138篇 |
1980年 | 134篇 |
1979年 | 109篇 |
1978年 | 102篇 |
1977年 | 92篇 |
1976年 | 66篇 |
1973年 | 81篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
水面长航舰载保存血液生化指标的实验研究 总被引:1,自引:1,他引:0
目的探讨和观察经水面长航舰载保存血液出海前后对生化指标的影响与变化。方法随机采集和制备WB、AS-RBC和LP-RBC各18人份(200ml)。每份血液各等分为4袋,配对设计为实验组(A区、B区和C区)与对照组。分别于长航前和长航后进行血液生化指标检测。结果①K+和P3+浓度在三种血液制品的实验组与对照组各观察点的结果均随保存血液时间的延长而增高(P<0.05或P<0.01);Na+浓度由长航前的水平而逐步降低(P<0.01);P3+、Mg2+实验组和对照组较长航前增高,Cl-、Ca2+的含量与长航前没有显著变化;②LDH、AST、CKP和HBDH结果实验组和对照组均呈递增趋势,AKP结果实验组和对照组均呈下降表现,ALT与GGT结果在长航前后变化不明显;③Glu指标减低,UA呈上升趋势。结论长航对血液保存有一定的影响,但总的变化趋势与常规(4±2)℃血库冰箱保存相似。此项研究对于我们进一步探索海上血液保障与运输以及血液海上救护均具有十分重要的实用和军事价值。 相似文献
62.
WEIGUANG ZENG PIERRE-OLIVIER REGAMEY KEITH ROSE YUZHOU WANG ERNST BAYER 《Chemical biology & drug design》1997,49(3):273-279
The use of N, O-bisFmoc-N-(2-hydroxy-4-methoxybenzyl) amino acid derivatives in the synthesis of peptides with difficult sequences has already been described. With these amino acid derivatives the reversible protecting group 2-hydroxy-4-methoxybenzyl (Hmb) for the backbone amide bonds of peptide chains is introduced, and thus the aggregation due to hydrogen-bond interchain association is inhibited. This paper describes the synthesis and use of Fmoc-N-(2-hydroxy-4-methoxybenzyl)amino acid derivatives as an alternative means of introducing Hmb backbone protection. These new monoFmoc derivatives were obtained in higher yield than the bisFmoc derivatives. Coupling yields to the amino peptide resin were the same as those obtained with bisFmoc derivatives, under the TBTU/HOBt/DIEA conditions. We also compared different syntheses of a difficult peptide with the Fmoc approach [triple coupling, capping, use of chaotropic agents, backbone protection using monoFmoc (Hmb)Ala] and with optimized Boc chemistry. Both the backbone protection and optimized Boc chemistry approaches gave the desired product in excellent yield and purity. © Munksgaard 1997. 相似文献
63.
胸腰椎压缩性骨折的护理要点 总被引:2,自引:0,他引:2
胸腰椎压缩性骨折的护理要点福建漳州市中医院(363000)郭燕玲,陈联源我院自1989年来对胸腰椎压缩性骨折实行辨证护理,收到满意效果,介绍如下。常规护理:屈曲型胸腰椎压缩性骨折,令病人仰卧在硬板床上,骨折处垫一软枕头,在耐受的情况下逐渐增加枕头高度... 相似文献
64.
Pamela H. Orr Victor Dong Marlis L. Schroeder Malcolm R. Ogborn 《Pediatric nephrology (Berlin, Germany)》1995,9(5):612-613
P1 blood group positivity has been postulated as a host factor which may provide protection against the development of post-enteropathic hemolytic uremic syndrome (HUS). In this study, blood group status in 20 Inuit survivors ofEscherichia coli 0157: H7-associated HUS was compared with age-and sex-matched controls from the same community who had experienced uncomplicated diarrheal illness due to the same pathogen. Of 20 HUS survivors, 6 were P1 antigen positive compared with 8 of the 20 controls (P=0.7). We conclude that P1 antigen positivity was not protective against HUS in this population. Further studies of this condition to clarify the role of host factors in verotoxin-induced endothelial damage are indicated. 相似文献
65.
RACHEL PHILOSOF-OPPENHEIMER ISRAEL PECHT MATI FRIDKIN 《Chemical biology & drug design》1995,45(2):116-121
The facile thiolytic cleavage of the O-2,4-dinitrophenyl (Dnp) tyrosine bond was applied to the solid-phase synthesis of the 22-amino acid residue peptide H-Asp-Ala-Val-Tyr -Thr-Gly-Leu-Asn-Thr-Arg-Asn-Gln-Glu-Thr-Tyr -Glu-Thr-Leu-Lys-His-Glu-Lys-OH, corresponding to positions 62-83 in the chain of the type 1 receptor for Fcε, domains expressed on the rat mucosal-type mast cells (line RBL-2H3). A method for the spectrophotometric determination of insoluble O-Dnp as well as of unprotected phenolic moieties of tyrosine was developed. It is based on monitoring S-Dnp-2-mercaptoethanol, produced upon O-Dnp thiolysis by 2-mercaptoethanol. © Munksgaard 1995. Dedicated to the memory of Dr. Susumu Funakoshi, a dear friend and a leader in peptide chemistry. 相似文献
66.
Hui Liu Tetsuzo Agishi Hideiku Suga Yutaro Hayasaka Satoshi Teraoka Kazuo Ota 《Artificial organs》1995,19(4):324-327
Abstract: Prevention of hyperacute rejection is a difficult and unsolved problem in xenotransplantation. Natural antibodies and complement activation have been known to play an important role in the xenotransplantation between discordant species pairs. In the present study, total blood exchange (TBE) was performed with pyridox-alated-hemoglobin-polyoxyethylene conjugate (PHP) solution (Ajinomoto Co., Inc., Kawasaki, Japan) before cardiac xenotransplantation in order to remove the immunoglobulins and prolong xenograft survival time. Guinea pigs and rats were used as the discordant species combination for donor and recipient. Two groups were established: Group 1, untreated control (n = 8) and Group 2, TBT with PHP solution (n = 8). The exchange blood transfusion was carried out at the rate of 15–20 ml/h utilizing PHP solution using a blood pump. After the blood exchange was processed, hematocrit (Ht) levels dropped to 4 or 5%, and a cardiac xenotransplantation was performed within 24 h. The levels of serum IgA, IgM, and IgG were decreased to less than 25, 25, and 10% of the base line, respectively, after blood exchange. A mean xenograft survival time in Group 2 was prolonged to 472 ± 74 min and to 10.4 ± 1.8 min in Group 1 (p < 0.01). A titer of the anti-guinea pig lymphocytotoxic antibody in rat serum was decreased to almost nil. The data from this study suggest that total blood exchange with PHP solution may be useful in preoperative removal of xenograft antibodies in xenotransplantation. 相似文献
67.
Brigden Geoffrey Zanelli Giussepe Lahiri Avijit Raftery Edward 《European journal of nuclear medicine and molecular imaging》1990,16(11):795-799
A new, single bolus method of in vivo blood pool imaging using a technetium Tc99m phosphine isocyanide complex (DEPIC) which binds to pre-albumin was evaluated in volunteers (n=4) and patients (n=20). DEPIC was assessed for its safety and possible drug interactions. Its duration of action and quality of ventriculography were compared with imaging using standard in vivo red cell labelling (PYP) during two 3-h scanning periods 1 week apart. DEPIC had a mean plasma halflife of 3.3 h. The count rate over the left ventricle was initially 42% higher with DEPIC than with PYP. However, removal of DEPIC by the liver resulted in equivalent count rates by 1 h, and by 3 h PYP count rates were 22% higher than DEPIC. Immediately post injection mean (SD) difference in the left ventricular ejection fraction between the two methods was 2.4% (7.7%). Satisfactory DEPIC scans were obtained up to 2 h post injection, but by 3 h there was a mean difference of 13% (11.3%). DEPIC was found to be a safe alternative to red all labelling for blood pool angiography, suitable for routine work. The single bolus methodology and high initial count rates offer improved efficiency and a capability for truly emergency scanning. 相似文献
68.
林丽星 《兰州大学学报(医学版)》1998,24(3):33-35
目的:探讨新生儿窒息后血糖,血气,心肌酶(谷草转氨酶,磷酸肌酸激酶及乳酸氢酶)的变化及其相关性。方法;血糖采用微量血糖仪测定,血气用足跟动脉化毛细血管法,心肌酶采用酶偶联连续监测,相关分析采用多元线性回归法。结果:低血糖8例,高血糖3例;36例均存在着不同程度的低氧血症和混合性酸中毒;22例心肌酶活性增高。血糖值与日龄呈负相关,与体温呈正相关,心肌酶活性男性高于女性,各酶之间有一定的相关性,但并非 相似文献
69.
为探讨冠心病患者血糖与微量元素的关系,用电感耦合等离子体原子发射光谱法测定了78例冠心病患者的6种微量元素变化,并与血糖做相关分析.结果冠心病患者高血糖组与正常血糖组相比,血清铁、铅、镉显著增高,锌和铬显著降低,P<005或001,铜无显著性差异;血糖与血清铁、铅呈显著性正相关,与血清铬、锌呈显著负相关,而与铜、镉相关不显著.表明部分微量元素的不平衡构成对冠心病的危险因子———高血糖的促发作用,调整人群中微量元素的不平衡状态,对减少冠心病及糖尿病的发生可能有利 相似文献
70.
The involvement of children in research studies is historically fraught with difficulties. Experiments on children without their consent or knowledge have been carried out in the past and thus the need for stringent ethical control is undoubtedly necessary. However this paper argues that the need to protect children from unethical research has somehow become entwined in the web of secrecy that surrounds the very nature of child abuse. In the name of 'protection' are children in danger of not having their voice heard?
In the foreword to 'Listening to Children' (Alderson, 1995) Roger Singleton writes, 'much research is carried out on and about children, but seldom with children. Children themselves are often strangely silent'. This paper draws on recent literature on the institutional abuse of young people in residential care and the lack of voice that those abused in residential care have traditionally had, suggesting that their silence is not 'strange' but perhaps contrived.
This paper does not repeat the work of Alderson (1995) and make suggestions as to how research with children may best be carried out, but seeks to address the issues in relation to research with children who are in institutions. 相似文献
In the foreword to 'Listening to Children' (Alderson, 1995) Roger Singleton writes, 'much research is carried out on and about children, but seldom with children. Children themselves are often strangely silent'. This paper draws on recent literature on the institutional abuse of young people in residential care and the lack of voice that those abused in residential care have traditionally had, suggesting that their silence is not 'strange' but perhaps contrived.
This paper does not repeat the work of Alderson (1995) and make suggestions as to how research with children may best be carried out, but seeks to address the issues in relation to research with children who are in institutions. 相似文献