首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   11880篇
  免费   493篇
  国内免费   109篇
耳鼻咽喉   194篇
儿科学   233篇
妇产科学   150篇
基础医学   1428篇
口腔科学   206篇
临床医学   613篇
内科学   3361篇
皮肤病学   191篇
神经病学   847篇
特种医学   537篇
外科学   1894篇
综合类   48篇
一般理论   5篇
预防医学   363篇
眼科学   276篇
药学   857篇
中国医学   33篇
肿瘤学   1246篇
  2023年   72篇
  2022年   117篇
  2021年   206篇
  2020年   100篇
  2019年   148篇
  2018年   192篇
  2017年   184篇
  2016年   239篇
  2015年   226篇
  2014年   298篇
  2013年   401篇
  2012年   649篇
  2011年   692篇
  2010年   376篇
  2009年   350篇
  2008年   663篇
  2007年   730篇
  2006年   746篇
  2005年   733篇
  2004年   729篇
  2003年   708篇
  2002年   749篇
  2001年   242篇
  2000年   258篇
  1999年   263篇
  1998年   204篇
  1997年   135篇
  1996年   126篇
  1995年   101篇
  1994年   101篇
  1993年   119篇
  1992年   170篇
  1991年   164篇
  1990年   153篇
  1989年   135篇
  1988年   114篇
  1987年   105篇
  1986年   104篇
  1985年   73篇
  1984年   69篇
  1983年   59篇
  1982年   42篇
  1981年   35篇
  1980年   29篇
  1979年   48篇
  1978年   29篇
  1972年   23篇
  1971年   23篇
  1969年   28篇
  1966年   29篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
A 18-year-old boy was admitted to hospital in an unconsciousness state as a result of taking a large dose of several psychotropic drugs simultaneously in an attempt to commit suicide. Blood studies revealed hypoxia (55.7 mmHg) and hypercapnia (59.7 mmHg). Hypoxia (74.3 mmHg) and hypercapnia (46.7 mmHg) were still present on the fourth day after admission, and the patient was becoming lethargic. Reduced vascular markings in the right upper lung field on chest roentgenogram in spite of hypercapnia suggested that the persistent hypoxia was the result of a pulmonary embolism. This diagnosis was supported by a perfusion defect on 99mTc-MAA scintigram and arterial obstruction in right pulmonary angiogram. Hypercapnia is an unusual finding in pulmonary embolism, and in this case was considered due to depression of respiration by psychotropic drugs.  相似文献   
13.
The purpose of this study was to determine the relationship between segmental hyperintensity of the liver on T1-weighted images and segmental cholestasis in patients with obstructive jaundice. T1-weighted and T2-weighted MR images were obtained of 73 patients with obstructive jaundice caused by various diseases. Fat-suppressed T1-weighted images were also obtained of 10 patients. Eleven patients with segmental intra-hepatic bile duct dilatation (cholestasis) showed segmental hyperintensity on T1-weighted images and/or fat-suppressed T1-weighted images and no signal intensity difference on T2-weighted images. Sixty-two patients with widespread intrahepatic bile duct dilatation showed no intensity difference on T1-weighted and T2-weighted images (P < .01). Segmental hyperintensity on T1-weighted images was correlated with intrahepatic cholestasis.  相似文献   
14.
Wilms tumor gene (WT-1) expression has been reported in many human cancers, including most ovarian and peritoneal serous carcinomas, but has not been studied in carcinomas of the fallopian tube. In this study, the authors evaluated the immunohistochemical expression of WT-1 in serous carcinomas of the fallopian tube and compared their reactivity with that of ovarian, peritoneal, and endometrial serous carcinomas. All primary serous carcinomas of the fallopian tube (13 cases), ovaries (25 cases), and peritoneum (3 cases) were reactive with the WT-1 antibody, whereas all five primary endometrial serous carcinomas were nonreactive. WT-1 reactivity in an unknown primary serous carcinoma is therefore suggestive of an extrauterine site. The marked difference in WT-1 staining raises the possibility of genetic differences between serous carcinomas arising in the endometrium compared with those arising in the ovaries, fallopian tubes, and peritoneum.  相似文献   
15.
Y Makino  S Ueda  M Ogawa  J Hori  M Ohto  M Wakashin  E Tanabe 《Ryūmachi》1992,32(4):340-5; discussion 345-6
Sweet's syndrome (acute febrile neutrophilic dermatosis) is an unusual condition characterized by fever, polymorphonuclear neutrophil leukocytosis of the blood, thick painful plaques on the face, neck and limbs, and a dense dermal infiltrate of mature neutrophils seen histologically. Recently, this disease has also been reported in association with various malignant neoplasms and chronic inflammatory disorders. In the literature, seven cases of Sweet's syndrome associated with collagen diseases have been reported, but no cases with mixed connective tissue disease (MCTD). The first case of Sweet's syndrome associated with MCTD was herein described and discussed. A 49-year-old man was admitted to our hospital with the complaints of high fever and painful erythema on his face, neck and limbs. Six months ago, MCTD was suspected, with the presence of limited cutaneous sclerosis of the hands, Raynaud's phenomenon, polyarthralgia, an elevation of CPK value and a positive anti-RNP antibody. Just before hospitalization, he suffered a prodromal infection of the upper respiratory tract for two weeks. He was diagnosed as Sweet's syndrome by the clinical and histological features. He began receiving corticosteroid therapy (prednisolone 60 mg/day), and within a week he showed dramatic improvement in the above symptoms.  相似文献   
16.
We assessed the period of administration of antibiotics required for cases of mycoplasmal pneumonia. The subjects were 38 patients with mycoplasmal pneumonia admitted to our hospital. These patients were treated with 100 mg minocycline or 500 mg erythromycin by intravenous infusion twice a day. They were divided into a 6 day-administration group (Group A; 16 cases) and a 9 day-administration group (Group B; 17 cases). Administration was discontinued on the 4th day or earlier in 5 cases due to side effects. A comparative assessment was made between Groups A and B with respect to body temperature, WBC, erythrocyte sedimentation rate, CRP, and chest X-ray on the 3rd, 6th, and 9th days of treatment, but no significant difference was observed. Residual shadows at the end of treatment were present in 100% of Group A and in 47% of Group B, but they disappeared gradually in both groups. No cases of recurrence were observed in either Group A or B within 1 month after the completion of treatment. Regarding the treatment period for mycoplasmal pneumonia by intravenous infusion of minocycline or erythromycin, no significant clinical difference was observed between the 6 day-administration group and the 9 day-administration group, suggesting that 6 days of administration is sufficient for treatment.  相似文献   
17.
We investigated the effects of age and naftidrofuryl oxalate (Naftidrofuryl), a 5-HT2 antagonist, on neurotransmission and transduction systems in the gerbil hippocampus using quantitative autoradiography. [3H]Quinuclidinyl benzilate (QNB), [3H]cyclohexyl-adenosine (CHA), [3H]MK-801, and [3H]muscimol were used to label muscarinic acetylcholine, adenosine A1, N-methyl-d-aspartate (NMDA), and γ-aminobutyric acid-A (GABAA) receptors, respectively. [3H]PN200-110 labeled L-type Ca2+ channels. [3H]Forskolin, [3H]cyclic adenosine monophosphate (cAMP), [3H]phorbol 12,13-dibutyrate (PDBu), and [3H]inositol 1,4,5-triphosphate (IP3) were used to label adenylate cyclase, cAMP-dependent protein kinase, protein kinase C (PKC), and IP3 receptors, respectively. Approximately 20% reductions in [3H]QNB, [3H]forskolin, and [3H]PDBu binding were observed in the hippocampus of 9-month-old gerbils in comparison with 5-week-old gerbils. Treatment with Naftidrofuryl (10 mg/kg, i.p., once a day for 7 days) ameliorated these reductions. No changes were found in [3H]CHA, [3H]MK-801, [3H]muscimol, [3H]PN200-110, [3H]cAMP, and [3H]IP3 binding. The results suggest that Naftidrofuryl may have beneficial effects on the age-related alterations in signal transmission and transduction systems in the brain. Because the acetylcholine system, adenylate cyclase, and PKC are considered to be involved in learning and memory processes, the result may have clinical implications.  相似文献   
18.
Thrombotic microangiopathy (TMA) may develop after living donor liver transplantation (LDLT), but the mechanism is not fully understood. We retrospectively analyzed all patients undergoing LDLT at our center, including TMA patients, to elucidate the clinical characteristics and presentation and to determine which patients have a higher risk of occurrence of TMA. In all, 57 adult patients were reviewed after LDLT at our institution. TMA was diagnosed by sudden and severe thrombocytopenia, followed by hemolytic anemia with fractionated erythrocytes in the blood smear. Clinical features were compared between the TMA group and the non-TMA group. Of the 57 patients, 4 were diagnosed with posttransplantation TMA. ABO blood group (ABO)-incompatibility, cyclophosphamide (CPA), and recipient blood group (type O) were closely correlated with the occurrence of TMA. Thrombocytopenia appeared 1 to 5 days before hemolytic anemia. Coagulative function markers stayed at the same level after TMA, while marked elevation was shown in fibrinolytic function markers such as plasminogen activator inhibitor type 1 (PAI-1). TMA occurred at a higher prevalence in ABO-incompatible graft recipients. Additional factors associated with ABO-incompatible transplantation, such as an overdose of immunosuppressants, may affect the likelihood of TMA. Sudden and severe thrombocytopenia presented before hemolytic anemia and the serum levels of PAI-1 correlated well with the clinical course of TMA. In conclusion, early recognition of thrombocytopenia and elevation of PAI-1 is crucial to diagnose TMA especially in ABO-incompatible LDLT.  相似文献   
19.
The majority of skull base tumors have been considered inoperable not because of the difficulty of surgical removal, but for lack of reliable methods to reconstruct the skull base following extensive removal of those tumors. In this report a trial fo reconstruction using a transplanted omentum is described. A free sheet of vascularized omentum was taken via laparotomy and transplanted into the skull base in four patients who had undergone extensive resection of skull base tumors. The transplanted omentum served satisfactorily as a barrier to prevent CSF leakage and subsequent infection and was considered to be a reliable material to reconstruct large defects in the skull base. The advantage of the omentum is its applicability in covering defects of all sizes and shapes. The omentum also contains various factors to promote tissue adhesion, such as angiogenic factors and fibroblastic growth factors. Furthermore, it can be expected to prevent secondary infections of the transplanted area, and as being a defense organ in the abdominal cavity. Practical methods to harvest and transplant the free vascularized omentum are described, and four cases of patients who have undergone these procedures are reported.  相似文献   
20.
We investigated the effects of a novel platelet-activating factor (PAF) receptor antagonist, CIS-19 [cis-2-(3, 4-dimethoxyphenyl)-6-isopropoxy-7-methoxy-1-(N-methylformamido)-1, 2, 3, 4-tetrahydronaphthalene], on PAF-, histamine-, substance P- and antigen-induced bronchoconstriction and microvascular leakage, as well as PAF- and antigen-induced bronchial hyperreactivity to methacholine in urethane-anesthetized guinea-pigs. Administration of CIS-19 (0.5–5 mg/kg, i.v.) inhibited the increase in lung resistance induced by PAF (30 ng/kg, i.v.) in a dose-dependent manner, but failed to inhibit the increase induced by histamine (30 μg/kg, i.v.) or substance P (6.5 μg/kg, i.v.). CIS-19 (5 mg/kg, i.v.) did not inhibit the increase in lung resistance induced by ovalbumin (2 mg/kg, i.v.) in actively sensitized guinea-pigs. PAF (30 ng/kg, i.v.)-induced microvascular leakage, measured by the extravasation of Evans blue dye, was dose-dependently inhibited by CIS-19 (0.5–5 mg/kg, i.v.) in the trachea, main bronchi and intrapulmonary airways, but it did not affect histamine (30 μg/kg, i.v.)- or substance P (6.5 μg/kg, i.v.)-induced microvascular leakage at all airway levels. CIS-19 (2.5 and 5 mg/kg) did not affect ovalbumin (2 mg/kg, i.v.)-induced microvascular leakage in all airway levels in actively sensitized guinea-pigs. CIS-19 (2.5 and 5 mg/kg, i.v.) significantly inhibited PAF-induced enhancement of the bronchial response to methacholine, but had no effect on ovalbumin (0.05 mg/kg, i.v.)-induced bronchial hyperreactivity in actively sensitized guinea-pigs. It is concluded that CIS-19 is a potent PAF receptor antagonist which inhibits PAF- but not antigen-induced bronchoconstriction, microvascular leakage and bronchial hyperreactivity. These results suggest that PAF plays little or no role in early airway responses following antigen challenge. Received: 29 April 1996 / Accepted: 10 October 1996  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号