全文获取类型
收费全文 | 6488篇 |
免费 | 313篇 |
国内免费 | 47篇 |
专业分类
耳鼻咽喉 | 37篇 |
儿科学 | 193篇 |
妇产科学 | 41篇 |
基础医学 | 972篇 |
口腔科学 | 131篇 |
临床医学 | 321篇 |
内科学 | 1814篇 |
皮肤病学 | 94篇 |
神经病学 | 325篇 |
特种医学 | 253篇 |
外科学 | 1141篇 |
综合类 | 20篇 |
预防医学 | 205篇 |
眼科学 | 74篇 |
药学 | 415篇 |
中国医学 | 21篇 |
肿瘤学 | 791篇 |
出版年
2023年 | 28篇 |
2022年 | 68篇 |
2021年 | 155篇 |
2020年 | 86篇 |
2019年 | 121篇 |
2018年 | 130篇 |
2017年 | 106篇 |
2016年 | 152篇 |
2015年 | 166篇 |
2014年 | 223篇 |
2013年 | 260篇 |
2012年 | 403篇 |
2011年 | 434篇 |
2010年 | 258篇 |
2009年 | 249篇 |
2008年 | 433篇 |
2007年 | 440篇 |
2006年 | 415篇 |
2005年 | 434篇 |
2004年 | 413篇 |
2003年 | 391篇 |
2002年 | 392篇 |
2001年 | 73篇 |
2000年 | 71篇 |
1999年 | 76篇 |
1998年 | 108篇 |
1997年 | 94篇 |
1996年 | 67篇 |
1995年 | 59篇 |
1994年 | 56篇 |
1993年 | 61篇 |
1992年 | 41篇 |
1991年 | 52篇 |
1990年 | 41篇 |
1989年 | 31篇 |
1988年 | 35篇 |
1987年 | 24篇 |
1986年 | 22篇 |
1985年 | 24篇 |
1984年 | 19篇 |
1983年 | 21篇 |
1982年 | 15篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 6篇 |
1978年 | 10篇 |
1977年 | 9篇 |
1976年 | 10篇 |
1970年 | 6篇 |
1966年 | 6篇 |
排序方式: 共有6848条查询结果,搜索用时 15 毫秒
31.
Tadashi Nakazawa Yoshiyuki Takami Robert Benkowski Satoshi Ohtsubo Ohashi Yukio Eiki Tayama Goro Ohtsuka Yoshinari Niimi Julie Glueck Akinori Sueoka Helmut Schmallegger Heinrich Schima Ernst Wolner Yukihiko Nosé 《Artificial organs》1997,21(7):597-601
Abstract: To be able to salvage heart failure patients, the need for an economical permanent ventricular assist device is increasing. To meet this increasing demand, a miniaturized centrifugal blood pump has been developed as a permanently implantable device. The Gyro permanently implantable model (PI-601) incorporates a sealless design with a blood stagnation free structure. The pump impeller is magnetically coupled to the driver magnet in a sealless manner. This pump is atraumatic and antithrombogenic and incorporates a double pivot bearing system. A miniaturized actuator was utilized in this system in collaboration with the University of Vienna. The priming volume of this pump is 20 ml. The overall size of the pump actuator package is 53 mm in height and 65 mm in diameter, 145 ml of displacement volume, and 305 g in weight. Testing to date has included in vitro hydraulic performance and hemolysis. This pump can provide 5 L/min against a 110 mm Hg total pressure head at 2,000 rpm and 8 Limin against 150 mm Hg at 2,500 rpm. The normalized index of hemo-lysis (NIH) value of this pump was 0.0028 g/100 L at 5 Limin against 100 mm Hg. A preliminary anatomical study revealed the possibility of the implantability of 2 such systems in biventricular bypass at a preperitoneal location. This system is feasible for use as a permanently implantable biventricular assist device. 相似文献
32.
33.
Masataka Nagao Wei-dong Zhang Yoshiyuki Itakura Masahiko Kobayashi Yoshihiro Yamada Katsunori Yagi Tsuneaki Oono Takehiko Takatori 《International journal of legal medicine》1993,106(3):142-144
Summary The dynamics of paraquat in the stomach and esophagus of rats were demonstrated using immunohistochemical techniques. The Rats were killed 3 h, 12 h, 24 h, 3 days, 7 days and 10 days after intravenous administration of paraquat. In the stomach, paraquat was localized in the epithelial cells between 24h and 10 days after injection, whereas in the esophagus, paraquat was localized in epithelial cells and the lamina propria mucosa between 12 h and 10 days after administration. Although these findings were similar to those observed in the intestine of rats, no clear changes in the distribution of paraquat with time were observed; suggesting that the stomach and esophagus are important reservoirs for the redistribution of paraquat. 相似文献
34.
The accumulation of oxygen free radicals is reported to occur in the organs subjected to temporary ischemia followed by reperfusion, resulting in the fatal outcome of the animals. The effects of human SOD, a representative scavenger of oxygen free radicals, on the survival rates were investigated in the rats with temporary splanchnic ischemia. The temporary ischemia was induced by the occlusion of anterior mesenteric and celiac arteries for 30min under anesthesia. Prior and after treatment with 2mg/100g of human SOD, iv or sc, produced significant improvements in survival rates. Human SOD, cloned from human placenta DNA and expressed in microorganisms, has extreme homogeneity. The results suggest the possible introduction of human SOD into clinical field as an effective scavenger of oxygen free radicals.(Ogawa R, Bitoh H, Ohi Y: The effect of human SOD on the survival rate in rats with temporary splanchnic ischemia. J Anesth 2: 41–45, 1988) 相似文献
35.
Hikaru Matsuda Yoshiyuki Taenaka Nobukazu Ohkubo Masakatu Ohtani Kyouichi Nishigaki Shigeaki Ohtake Takuya Miura Nobuyuki Taenaka† Hisateru Takano Hajime Hirose Yasunaru Kawashima 《Artificial organs》1988,12(5):423-430
Pneumatic ventricular assist device (VAD) was utilized for cardiogenic shock after intracardiac operation in two children with complex cardiac anomalies based with single ventricle. In the first case (a 10-year-old), after a modified Fontan operation, VAD was placed between the functional left atrium and ascending aorta, serving as a "artificial single ventricle" with neither pumping chamber nor artificial support in the right side of the heart. The systemic circulation was maintained by keeping relatively high central venous pressure. In another child (a 3-year-old) who underwent repair of incompetent atrioventricular valve leaving intracardiac lesions, VAD was placed between the common atrium and ascending aorta, serving as a pump for both pulmonary and systemic circulation with regulation of pulmonary blood flow through an aortopulmonary Gore-Tex shunt. The circulatory assist with VAD was utilized for 5 and 6 days, respectively. Although weaning from the device was not feasible in both patients because of the pulmonary dysfunction, these experience showed the possible use of VAD for cardiogenic shock after surgery in patients with complex cardiac anomalies. 相似文献
36.
Contribution of Asian mouse subspecies Mus musculus molossinus to genomic constitution of strain C57BL/6J, as defined by BAC-end sequence-SNP analysis 下载免费PDF全文
Abe K Noguchi H Tagawa K Yuzuriha M Toyoda A Kojima T Ezawa K Saitou N Hattori M Sakaki Y Moriwaki K Shiroishi T 《Genome research》2004,14(12):2439-2447
MSM/Ms is an inbred strain derived from the Japanese wild mouse, Mus musculus molossinus. It is believed that subspecies molossinus has contributed substantially to the genome constitution of common laboratory strains of mice, although the majority of their genome is derived from the west European M. m. domesticus. Information on the molossinus genome is thus essential not only for genetic studies involving molossinus but also for characterization of common laboratory strains. Here, we report the construction of an arrayed bacterial artificial chromosome (BAC) library from male MSM/Ms genomic DNA, covering approximately 1x genome equivalent. Both ends of 176,256 BAC clone inserts were sequenced, and 62,988 BAC-end sequence (BES) pairs were mapped onto the C57BL/6J genome (NCBI mouse Build 30), covering 2,228,164 kbp or 89% of the total genome. Taking advantage of the BES map data, we established a computer-based clone screening system. Comparison of the MSM/Ms and C57BL/6J sequences revealed 489,200 candidate single nucleotide polymorphisms (SNPs) in 51,137,941 bp sequenced. The overall nucleotide substitution rate was as high as 0.0096. The distribution of SNPs along the C57BL/6J genome was not uniform: The majority of the genome showed a high SNP rate, and only 5.2% of the genome showed an extremely low SNP rate (percentage identity = 0.9997); these sequences are likely derived from the molossinus genome. 相似文献
37.
38.
Kiyoshi A Ishikawa T Hayashi K Iwatsuki Y Ishii K Nakayama K 《Pflügers Archiv : European journal of physiology》2003,447(2):142-149
Rhythmical contractions accompanied by an increase in cytosolic Ca2+ concentrations were produced in ring preparations of endothelium-denuded pulmonary arteries from monocrotaline-treated rats, but not in those from vehicle-treated rats, 2-3 h after a resting tension of 15 mN (150-180% of the initial wall length of the artery) was applied. The rhythmical contractions were abolished by nicardipine and ryanodine. Cyclopiazonic acid reduced the relaxation phase of the rhythmical contractions, finally leading to a sustained contraction. Similarly, apamin caused a sustained contraction, whereas charybdotoxin increased the amplitude of the rhythmical contractions. Glibenclamide had no apparent effects on them. Indomethacin and the prostaglandin H2/thromboxane A2 receptor antagonist SQ29548 abolished the rhythmical contractions and reduced the tension, but the thromboxane synthase inhibitor ozagrel had no effect. These results suggest that optimal stretch induces rhythmical contractions in the pulmonary arteries of monocrotaline-induced pulmonary hypertensive rats, to which both Ca2+ influx through voltage-operated Ca2+ channels and Ca2+ release from the endoplasmic reticulum seem to contribute. It is also suggested that small-conductance Ca(2+)-activated K+ channels participate in the relaxation phase of rhythmical contractions. Furthermore, prostaglandin H2 released from nonendothelial cells is likely to play a pivotal role in the induction of rhythmical contractions. 相似文献
39.
40.
The pre-B cell receptor (preBCR) plays critical roles in early B cell differentiation. It has been shown that not all muH chains are capable of pairing with surrogate light (SL) chains to form preBCR. Here, we established a novel system to differentially identify two types of early pre-B cell populations in bone marrow and fetal liver of mice, one producing SL-pairing muH chains and the other producing SL-non-pairing muH chains. The former population accounted for 80% of all the early pre-B cells in adult bone marrow, while it accounted for only 20% of those in fetal liver. Comparison of the two types of pre-B cell populations in fetal liver revealed the structural difference between SL-pairing and -non-pairing muH chains encoded by the V(H)81X segment that was most frequently utilized in fetal liver pre-B cells but rarely expressed by B cells generated in adults. PreBCR played an important role in the positive selection of V(H)81X-muH chains carrying the characteristic sequences of the complementarity-determining region 3 with little or no nibbling or N nucleotide addition, leading to their predominance in neonatal splenic B cells. These fetal-type V(H)81X-muH chains were also detected in adult spleen, but almost exclusively in marginal zone (MZ) B cells in contrast to the adult-type V(H)81X-muH chains. This strongly suggests that neonatally generated and selected B cells expressing the stereotyped V(H)81X-muH chains are maintained in the adult MZ and could function as innate-like lymphocytes. 相似文献