全文获取类型
收费全文 | 18801篇 |
免费 | 1355篇 |
国内免费 | 656篇 |
专业分类
耳鼻咽喉 | 99篇 |
儿科学 | 631篇 |
妇产科学 | 160篇 |
基础医学 | 2677篇 |
口腔科学 | 122篇 |
临床医学 | 1396篇 |
内科学 | 3493篇 |
皮肤病学 | 69篇 |
神经病学 | 1898篇 |
特种医学 | 421篇 |
外国民族医学 | 3篇 |
外科学 | 1861篇 |
综合类 | 2146篇 |
现状与发展 | 3篇 |
一般理论 | 1篇 |
预防医学 | 1128篇 |
眼科学 | 173篇 |
药学 | 2823篇 |
中国医学 | 1190篇 |
肿瘤学 | 518篇 |
出版年
2024年 | 69篇 |
2023年 | 301篇 |
2022年 | 652篇 |
2021年 | 768篇 |
2020年 | 534篇 |
2019年 | 540篇 |
2018年 | 488篇 |
2017年 | 524篇 |
2016年 | 557篇 |
2015年 | 546篇 |
2014年 | 785篇 |
2013年 | 1223篇 |
2012年 | 805篇 |
2011年 | 906篇 |
2010年 | 712篇 |
2009年 | 747篇 |
2008年 | 723篇 |
2007年 | 731篇 |
2006年 | 748篇 |
2005年 | 649篇 |
2004年 | 567篇 |
2003年 | 558篇 |
2002年 | 434篇 |
2001年 | 427篇 |
2000年 | 373篇 |
1999年 | 341篇 |
1998年 | 342篇 |
1997年 | 331篇 |
1996年 | 321篇 |
1995年 | 334篇 |
1994年 | 314篇 |
1993年 | 270篇 |
1992年 | 234篇 |
1991年 | 225篇 |
1990年 | 220篇 |
1989年 | 223篇 |
1988年 | 195篇 |
1987年 | 208篇 |
1986年 | 193篇 |
1985年 | 254篇 |
1984年 | 232篇 |
1983年 | 171篇 |
1982年 | 198篇 |
1981年 | 183篇 |
1980年 | 187篇 |
1979年 | 119篇 |
1978年 | 98篇 |
1977年 | 77篇 |
1976年 | 62篇 |
1974年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
32.
S. M. Manzurul Haque Kai Chen Noriaki Usui Yasuhiko Iiboshi Hiroomi Okuyama Akira Masunari Riichiro Nezu Yoji Takagi Akira Okada 《Surgery today》1997,27(6):500-505
The purpose of this study was to investigate the intestinal hemodynamics and gut glutamine metabolism during endotoxemia,
and their correlation with altered intestinal absorptive capacity and permeability. Seventeen Sprague-Dawley rats were used
in the study. The endotoxin group (ENDO) recieved endotoxin (10 mg/kg intraperitoneally,n=9), while the control group (CONT,n=8) received saline injection. Twelve hours later, D-xylose (0.5 g/kg) and fluorescein isothiocyanate-dextran (FITC-dextran,
750 mg/kg) were given by oral gavage. One hour later abdominal aortic (AA) blood flow, superior mesenteric venous (SMV) flow,
mean arterial pressure (MAP), central venous pressure (CVP), and SMV pressure (SMVP) were also measured. The MAP, AA, and
SMV blood flow decreased (P<0.05), while the CVP and SMVP increased (P<0.05) in the ENDO group as compared with the CONT group. The ENDO group showed significant decreases for both intestinal
glutaminase activity and net intestinal glutamine uptake (P<0.05). The D-xylose concentration in SMV decreased significantly (P<0.05) in the ENDO group as compared with the CONT group. However, the plasma FITC-dextran concentration showed no significant
difference between the groups. Endotoxin produced a hypodynamic effect in rats 12h after intraperitoneal administration in
association with both a decreased intestinal glutamine metabolism and an absorptive capacity. 相似文献
33.
The subdivisions of the sacral intermediolateral nucleus (IML) of the cat have been studied by using a double-labeling technique of retrograde Fluoro-gold (FG) and wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) tracing. The parasympathetic preganglionic neurons (PGNs) that were labeled by the FG injected into the pelvic nerve formed a ‘V’-shaped column known as the sacral parasympathetic nucleus (SPN) in the sacral IML. The neurons that were labeled by the WGA-HRP applied to the lateral parabrachial nucleus (PBL) formed an elongated spindle-shaped column extending throughout the IML of the sacral segments. We designated it by the name of sacral visceral sensory nucleus (SVSN). These findings indicate that the sacral IML of the cat contain two distinct subdivisions, SPN and SVSN. 相似文献
34.
ThedynamicdistributionofnitricoxidesynthaseinthesmallintestineofmicewithintestinalradiationsicknessWeiLichun(魏丽春);GuoYao(郭鹞)(... 相似文献
35.
Clinicopathologlc and mucin histochemical characteristics of 90 cases of ovarian mucinous borderline tumors (MBT) of Intestinal (IMET) and müllerian types (MMBT) were studied to determine whether IMBT and MMBT constitute distinct tumor subtypes. The IMBT (77 cases, 78 lesions) contained goblet cells, absorptive cells and endocrine cells, which represented Intestinal differentiation. The average diameter of IMBT was 13.4 cm. Five patients (6.5%) had stage III disease wtth pseudomyxoma perltonel and one of them died from tumor. Approximately 50% of IMBT demonstrated gastrointestinal characteistics on mucin histochemistry. The MMBT (13 cases, 14 lesions) consisted of mumus columnar cells and eosinophilic cells, with no Intestinal differentiation. MMBT accounted for 15.2% of MBT. MMBT averaged 8.4 cm in diameter, and 29% were associated with endometriosls of the ipsilateral ovary. All patients with MMBT had stage I disease, and none suffered from pseudomyxoma peritonel. All patients whose follow-up data were available were alive and well, without evidence of tumor recurrence. The mucin histochemical findings in MMBT resembled those of noml endocervix. Results of the present study suggest that IMBT and MMBT have different characteristics and constitute distinct subtypes of MBT. 相似文献
36.
Iwar Klime Antonian Vraana Jaroslav Kune Elena eboUkovaA Zdena Dobe ovaa Pavel tolba Josef Zicha 《Blood pressure》1995,4(3):137-142
Hereditary hypertriglyceridemic rats (hHTg) were developed as a new genetic model for the study of relationships between blood pressure (BP) and metabolic abnormalities. This strain has been produced by selective inbreeding from Wistar rats according to the rise of plasma triglycerides induced by a high-sucrose diet. Though hHTg rats display hypertriglyceridemia, impaired glucose tolerrance, hyperinsulinemia, insulin resistance and increased BP even without nutritional stimuli, high sucrose feeding further aggravates these symptoms. High plasma triglycerides levels in hHTg rats seem to be a consequence of their hyperproduction. Impaired insulin action is responsible for the defective glucoregulation in this strain. The loss of insulin responsiveness might be due to a reduction in the number of glucose transporters. Highly significant relationships among plasma triglycerides, ouabain-resistant Na+ transport and BP were demonstrated in the hHTg rats. Segregating populations (F2 hybrids) should be used for genetic analysis of the primary role of lipid and/or ion transport abnormalities in the pathogenesis of this form of genetic hypertension. 相似文献
37.
1. The effects of graded doses of the α2-adrenoceptor agonists clonidine, tizanidine and BHT-920, and the α2-adrenoceptor antagonists yohimbine and idazoxan, on gastrointestinal transit were investigated in mice using the charcoal meal test. 2. The agonists produced significant and dose-dependent decreases in gastrointestinal transit, and the antagonists produced the opposite effect. In affecting the gastrointestinal transit, clonidine (1 mg/kg) was as effective as tizanidine (12 mg/kg) and BHT-920 (40 mg/kg), while yohimbine (2 mg/kg) was as effective as idazoxan (1 mg/kg). 3. Morphine (2, 4 and 8 mg/kg) significantly inhibited gastrointestinal transit. This effect was significantly reversed by the co-administration of yohimbine (2 mg/kg) and idazoxan (1 mg/kg). 4. The acute administration of glucose (5.04 g/kg, i.p.) potentiated the inhibition of gastrointestinal transit produced by clonidine (1 mg/kg) and BHT-920 (40 mg/kg). Glucose treatment, however, had no significant effect on the increase in gastrointestinal transit induced by yohimbine (2 mg/kg) or idazoxan (1 mg/kg). 5. Castor oil (0.25 mL/mouse, orally) induced diarrhoea in saline-treated animals within about 45 min. Clonidine (1 mg/kg), tizanidine (12 mg/kg) and BHT-920 (40 mg/kg) delayed the occurrence of diarrhoea to 2.1, 1.2 and 1.4 h, respectively. 相似文献
38.
STEVEN N. VASLEF LYLE F. MOCKROS KEITH E. COOK RONALD J. LEONARD JEFFREY C. SUNG ROBERT W. ANDERSON 《Artificial organs》1994,18(11):813-817
Abstract: A semiempirical mathematical model of convective oxygen transport is used to design a new, low pressure loss, implantable artificial lung that could be used as a bridge to lung transplantation in patients with advanced respiratory failure. The mass transfer and flow friction relations pertinent to the design of a cross–flow hollow fiber membrane lung are described. The artificial lung is designed to transfer over 200 ml/min of oxygen at blood flow rates up to 5 L/min. A compact design and a blood-side pressure loss of <15 mm Hg allows the device to be implanted in the left chest without the need for a prosthetic blood pump. Surgical implantation of the artificial lung would require the creation of inflow and outflow anastomoses. Oxygen would be supplied via an external source. Blood properties, operating conditions, and empirically determined mass transfer and flow properties are all specified and input into a computer program that numerically solves the design equations. Computer–generated values for the device frontal area, blood path length, and fiber surface area are thereby obtained. The use of this computer–assisted design minimizes the need for extensive trial–and–error testing of prototype devices. Results from in vitro tests of a prototype implantable lung indicate that the mathematical model we describe is an accurate and useful tool in the design of hollow fiber artificial lungs. 相似文献
39.
Abstract: Ultrafiltration of water from blood to dialysate decreases the rate of back–diffusion of solutes from dialysate to blood. Therefore, back–clearance ( bK ) of hemodialyzers may be expressed as bK = bK o – bTrQ u , where bK o is the diffusive back–clearance, bTr is the "back–"transmittance coefficient, and Qu is the net ultrafiltration rate. A formula for bK was derived from the one–dimensional theory of hemodialyzer, and bTr was described as a function of bK o and the Staverman reflection coefficient. The transport parameters, bK o and bTr , for creatinine and vitamin B12 were measured in two types of hemodialyzers with negligible back–filtration, using water solutions, and compared with the transport parameters, K o and Tr , for the case of both diffusion and ultrafiltration from blood to dialysate. bK o was in general equal to Ko . bTr was not different from Tr for creatinine whereas bTr was lower than Tr for vitamin B12 . Experimental values of bTr for vitamin B12 were in general agreement with theoretical predictions. However, experimental values of bTr for creatinine were lower than predicted values. We conclude that the impact of ultrafiltration on back–clearance for slowly diffusing solutes is weaker than on their clearance. 相似文献
40.
E. Angelini M. Teixeira J.-M. Aran E. Ferrary 《European archives of oto-rhino-laryngology》1998,255(7):331-333
Taurine is a β-aminosulfonic acid and is a ubiquitous amino acid whose role in the cochlea is not well established. In this
study, its entry from blood into perilymph was investigated in the guinea pig as animal model. The penetration rate of [3H]taurine (molecular weight 125) into the perilymph of the scala vestibuli was measured 1 and 2 h after the intravenous infusion
of [3H]taurine in nephrectomized animals. Results showed a rate of penetration in perilymph related to plasma at 36 ± 4.7% (n = 5) after 1 h and 43 ± 5.6% (n = 5) after 2 h. Compared to the penetration rate of urea (molecular weight 60) and mannitol (molecular weight 186) reported
previously in rats, a passive entry of taurine into perilymph through the blood-perilymph barrier is suggested.
Received: 30 July 1997 / Accepted: 15 January 1998 相似文献