全文获取类型
收费全文 | 28901篇 |
免费 | 1870篇 |
国内免费 | 70篇 |
专业分类
耳鼻咽喉 | 252篇 |
儿科学 | 679篇 |
妇产科学 | 526篇 |
基础医学 | 4095篇 |
口腔科学 | 666篇 |
临床医学 | 2712篇 |
内科学 | 5494篇 |
皮肤病学 | 490篇 |
神经病学 | 3177篇 |
特种医学 | 1163篇 |
外国民族医学 | 57篇 |
外科学 | 4008篇 |
综合类 | 370篇 |
一般理论 | 10篇 |
预防医学 | 2263篇 |
眼科学 | 820篇 |
药学 | 1973篇 |
中国医学 | 32篇 |
肿瘤学 | 2054篇 |
出版年
2022年 | 194篇 |
2021年 | 394篇 |
2020年 | 239篇 |
2019年 | 394篇 |
2018年 | 442篇 |
2017年 | 370篇 |
2016年 | 416篇 |
2015年 | 561篇 |
2014年 | 735篇 |
2013年 | 1110篇 |
2012年 | 1627篇 |
2011年 | 1682篇 |
2010年 | 911篇 |
2009年 | 861篇 |
2008年 | 1590篇 |
2007年 | 1700篇 |
2006年 | 1630篇 |
2005年 | 1661篇 |
2004年 | 1571篇 |
2003年 | 1474篇 |
2002年 | 1448篇 |
2001年 | 439篇 |
2000年 | 376篇 |
1999年 | 392篇 |
1998年 | 322篇 |
1997年 | 307篇 |
1996年 | 274篇 |
1995年 | 256篇 |
1994年 | 227篇 |
1993年 | 231篇 |
1992年 | 259篇 |
1991年 | 240篇 |
1990年 | 216篇 |
1989年 | 222篇 |
1988年 | 207篇 |
1987年 | 223篇 |
1986年 | 187篇 |
1985年 | 195篇 |
1984年 | 248篇 |
1983年 | 205篇 |
1982年 | 236篇 |
1981年 | 219篇 |
1980年 | 199篇 |
1979年 | 185篇 |
1978年 | 156篇 |
1977年 | 114篇 |
1976年 | 150篇 |
1975年 | 133篇 |
1974年 | 158篇 |
1973年 | 122篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
Agenesis of the Gallbladder Revisited Laparoscopically 总被引:1,自引:0,他引:1
Najam Azmat M.D. Kenneth R. Francis M.D. Neal Mandava M.D. Walter F. Pizzi M.D. 《The American journal of gastroenterology》1993,88(8):1269-1270
Gallbladder agenesis is an extremely rare disease. Necropsy incidence has been reported to be 0.016%. Failure lo locate the gallbladder at the time of a planned cholecystectomy can be very challenging. We report such a case during a laparoscopic cholecystectomy. The indication for surgery in these patients are complaints of gallbladder symptoms along with a false-positive ultrasound study. During exploration, an abnormal location of the gallbladder has to be excluded. Ectopic gallbladder locations include intrahepatic, lesser omentum, retroperitoneal, retrohepatic, within the falciform ligament, retroduodenal, and retrohepatic areas. Thorough exploration and cholangiography are essential. Embryologically, the gallbladder and cystic duct arise from the caudal portion of the hepatic bud. All of the previously reported cases of gallbladder agenesis have shown an absence of both the gallbladder and cystic duct. We report an embryological oddity wherein a patent cystic duct was found along with an agenetic gallbladder. This is the first case report of this finding, along with this being the first absent gallbladder discovered laparoscopically. 相似文献
12.
Peter Chiba Barbara Tell Walter Jger Elisabeth Richter Manuela Hitzlera Gerhard Ecker 《Archiv der Pharmazie》1997,330(11):343-347
A series of 5-hydroxy and 5-benzyloxy analogs of the antiarrhythmic and multidrug resistance (MDR) modulating drug propafenone was synthesized and the MDR-modulating activity of the compounds was evaluated using a daunomycin efflux assay system. The key step of the synthesis is the selective reduction of the double bond in 1 without cleavage of the benzyl group thus leading to the phenol 3 . Alkylation with epichlorohydrine followed by nucleophilic epoxide ring opening gave the benzylated target compounds 5a–d . Subsequent cleavage of the benzyl group gave the 5-hydroxy analogs 6a–d . Structure activity relationship studies showed, that the 5-hydroxy derivates 6a–d fit the log P/log potency correlation line previously established for a series of propafenone analogs. In contrast, all four 5-benzyloxy analogs 5a–d showed almost identical EC50 values, independent of their log P value. 相似文献
13.
Inborn errors of the urea cycle are an important cause of hyperammonaemia throughout childhood, and are associated with high morbidity and mortality rates. If they are diagnosed early and treated appropriately, the outcome for affected children is significantly improved. 相似文献
14.
15.
Guerard W. Byrne Johannes M. Schirmer David N. Fass Sumeet S. Teotia Walter K. Kremers Hui Xu Bashoo Naziruddin Henry D. Tazelaar John S. Logan Christopher G. A. McGregor 《American journal of transplantation》2005,5(5):1011-1020
Microvascular thrombosis is a prominent feature in cardiac delayed xenograft rejection (DXR). We investigated the impact of warfarin or low-molecular-weight heparin (LMWH) anti-coagulation on xenograft function using a heterotopic pig-to-primate model. Donor hearts were from CD46 transgenic pigs and baboon immunosuppression included tacrolimus, sirolimus, anti-CD20 and TPC, an alpha-galactosyl-polyethylene glycol conjugate. Three groups of animals were studied. Group 1 (n = 9) was treated with warfarin, Group 2 (n = 13) with LMWH and Group 3, received no anti-coagulant drugs. The median duration of xenograft function was 20 days (range 3-62 days), 18 days (range 5-109 days) and 15 days (range 4-53 days) in Groups 1 to 3 respectively. Anti-coagulation achieved the targeted international normalized prothrombin ratio (INR) and anti-factor Xa levels consistent with effective in vivo therapy yet, no significant impact on median xenograft function was observed. At rejection, a similar histology of thrombosis and ischemia was apparent in each group and the levels of fibrin deposition and platelet thrombi in rejected tissue was the same. Anti-coagulation with warfarin or LMWH did not have a significant impact on the onset of DXR and microvascular thrombosis. However, a role for specific anti-coagulant strategies to achieve long-term xenograft function cannot be excluded. 相似文献
16.
17.
18.
Pedophilia is linked to reduced activation in hypothalamus and lateral prefrontal cortex during visual erotic stimulation. 总被引:2,自引:0,他引:2
Martin Walter Joachim Witzel Christine Wiebking Udo Gubka Michael Rotte Kolja Schiltz Felix Bermpohl Claus Tempelmann Bernhard Bogerts Hans Jochen Heinze Georg Northoff 《Neuropsychopharmacology》2007,62(6):698-701
BACKGROUND: Although pedophilia is of high public concern, little is known about underlying neural mechanisms. Although pedophilic patients are sexually attracted to prepubescent children, they show no sexual interest toward adults. This study aimed to investigate the neural correlates of deficits of sexual and emotional arousal in pedophiles. METHODS: Thirteen pedophilic patients and 14 healthy control subjects were tested for differential neural activity during visual stimulation with emotional and erotic pictures with functional magnetic resonance imaging. RESULTS: Regions showing differential activations during the erotic condition comprised the hypothalamus, the periaqueductal gray, and dorsolateral prefrontal cortex, the latter correlating with a clinical measure. Alterations of emotional processing concerned the amygdala-hippocampus and dorsomedial prefrontal cortex. CONCLUSIONS: Hypothesized regions relevant for processing of erotic stimuli in healthy individuals showed reduced activations during visual erotic stimulation in pedophilic patients. This suggests an impaired recruitment of key structures that might contribute to an altered sexual interest of these patients toward adults. 相似文献
19.
Kerstin Schmidt Johannes Hoffend Annette Altmann Ludwig G Strauss Antonia Dimitrakopoulou-Strauss Britta Engelhardt Dirk Koczan J?rg Peter Thomas J Dengler Walter Mier Michael Eisenhut Uwe Haberkorn Ralf Kinscherf 《Journal of nuclear medicine》2006,47(3):543-551
Growth of malignant tumors is dependent on sufficient blood supply. Thus, inhibition of tumor angiogenesis is emerging as a promising target in the treatment of malignancies. Human angiostatin (hANG) is one of the most potent inhibitors of endothelial cell proliferation, angiogenesis, and tumor growth in vivo. However, its mechanisms operating in vivo are not well understood. METHODS: To obtain more information about functional changes in the angiogenic process, we established Morris hepatoma (MH3924A) cell lines expressing hANG (hANG-MH3924A). The effects of hANG expression on proliferation and apoptosis of human umbilical vein endothelial cells (HUVECs) were measured in coculture experiments in vitro. To evaluate changes in tumor perfusion and blood volume, H2 15O and 68Ga-DOTA-albumin (DOTA is 1,4,7,10-tetraazacyclododecane-N,N',N',N'-tetraacetic acid) were used for PET studies in vivo. Additionally, immunohistologic quantification of vascularization, apoptosis, and proliferation as well as gene array analyses were performed. RESULTS: Our in vitro experiments demonstrate reduced proliferation and increased apoptosis in HUVECs when being cocultured with hANG-MH3924A. In support, tumor growth of hANG-MH3924A is diminished by 95% in vivo. However, tumor perfusion and blood volume are increased in hANG-MH3924A corresponding to an increased microvessel density. Furthermore, hANG-transfected tumors show changes in expression of genes related to apoptosis, stress, signal transduction, and metabolism. CONCLUSION: hANG expression leads to inhibition of tumor growth, increased apoptosis, and changes in the expression of multiple genes involved in stress reactions, signal transduction, and apoptosis, which indicates a multifactorial reaction of tumors. An enhanced microvessel density is seen as part of these reactions and is associated with increased perfusion as measured by PET. 相似文献
20.
Walter S. Nimmo 《Journal canadien d'anesthésie》1989,36(Z1):S45-S47
An understanding of factors which influence gastric emptying rate is important for anaesthetists. In the absence of pyloric
stenosis or other mechanical obstruction to the gastric outlet, opioid drugs constitute the most important cause of delayed
emptying in the perioperative period. 相似文献