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   8722篇
  免费   480篇
  国内免费   64篇
耳鼻咽喉   58篇
儿科学   159篇
妇产科学   175篇
基础医学   1024篇
口腔科学   165篇
临床医学   602篇
内科学   2253篇
皮肤病学   236篇
神经病学   492篇
特种医学   347篇
外科学   1424篇
综合类   17篇
预防医学   256篇
眼科学   131篇
药学   603篇
中国医学   26篇
肿瘤学   1298篇
  2023年   50篇
  2022年   120篇
  2021年   194篇
  2020年   113篇
  2019年   142篇
  2018年   170篇
  2017年   171篇
  2016年   196篇
  2015年   226篇
  2014年   226篇
  2013年   303篇
  2012年   475篇
  2011年   500篇
  2010年   269篇
  2009年   207篇
  2008年   375篇
  2007年   372篇
  2006年   383篇
  2005年   375篇
  2004年   320篇
  2003年   365篇
  2002年   338篇
  2001年   286篇
  2000年   271篇
  1999年   225篇
  1998年   113篇
  1997年   95篇
  1996年   81篇
  1995年   69篇
  1994年   45篇
  1993年   58篇
  1992年   182篇
  1991年   160篇
  1990年   152篇
  1989年   194篇
  1988年   195篇
  1987年   164篇
  1986年   153篇
  1985年   138篇
  1984年   85篇
  1983年   70篇
  1982年   46篇
  1981年   43篇
  1979年   74篇
  1978年   59篇
  1977年   39篇
  1976年   38篇
  1975年   36篇
  1974年   46篇
  1972年   37篇
排序方式: 共有9266条查询结果,搜索用时 15 毫秒
1.
Idiopathic myointimal hyperplasia of mesenteric veins (IMHMV) is a rare and poorly understood ischemic colitis that occurs in the rectosigmoid colon of predominantly young, previously healthy, male patients. A 76‐year‐old Japanese man presented to our hospital with a 1‐year history of worsening diarrhea, lower abdominal pain, and weight loss (−6 kg). Laboratory evaluation revealed white blood cell count of 13 200/μL, C‐reactive protein level of 2.0 mg/dL (normal range, 0.0–0.3), and negative results for stool culture (including Clostridium difficile). Colonoscopy showed circumferential and edematous narrowing of the sigmoid colon with deep longitude ulceration. Biopsy was done and examination of the specimen demonstrated no specific ischemia. The patient was treated with bowel rest, antibiotics, and i.v. fluids; however, his symptoms worsened. Finally, sigmoidectomy was carried out. Histological examination demonstrated significant myointimal hyperplasia of mesenteric veins leading to thickening and stenosis of the venous lumen. Therefore, the final diagnosis was IMHMV. Three months following sigmoidectomy, he was asymptomatic.  相似文献   
2.
3.
4.
OBJECTIVES: To determine the value of the loss of expression of E-cadherin and cadherin associated molecules as useful markers for both prognosis and chemosensitivity in bladder cancer patients who have undergone radical cystectomy. PATIENTS AND METHODS: In 55 paraffin embedded specimens of radical cystectomy at our hospital from 1982 to 2000, the expression of E-cadherin, alpha-, beta- and gamma-catenin was examined by immunohistochemical staining. To evaluate the prognostic significance of these molecules, Kaplan-Meier survival curves were constructed and a statistical analysis was calculated by a log-rank test. A multivariate test (tumor stage, tumor grade, lymph node metastasis, configuration, the expression of E-cadherin, alpha-, beta- and gamma-catenin) was performed to detect prognostic markers. RESULTS: Normal expression was found in 33 cases (60.0%) for E-cadherin, 29 (52.7%) for alpha-catenin, 31 cases (56.4%) for beta-catenin, and 31 cases (56.4%) for gamma-catenin. The expression patterns for E-cadherin, alpha-, beta- and gamma-catenin were significantly correlated with each other (P < 0.01). Survival analysis showed a significant difference between normal and aberrant expression in each staining. A multivariate analysis revealed that the expression of alpha- catenin was an independent prognostic factor (P = 0.0191). In 23 patients that received adjuvant chemotherapy, there was a significant difference in survival between the normal and aberrant expression of alpha-catenin, but not other molecules. CONCLUSION: Alpha-catenin may not only be a good prognostic marker, but also one of key molecules that determine the chemosensitivities in patients with invasive bladder cancer.  相似文献   
5.
Objective Self-expandable metallic stent (EMS) placement has been the first choice for dysphagia because of the certainty over its safety, low invasiveness, and immediate efficacy. However, there still remain some problems in relation to the EMS placement site and anticancer therapies before and after EMS placement. Methods: Consecutive 78 patients in whom EMS was placed due to the unresectable malignant stricture in the esophagus or cardia from July 1995 to August 2003 in our department were studied. Results: Gastroesophageal reflux was found in 5 of 8 patients after placement of conventional EMS for the stricture in the gastroesophageal junction. Meanwhile, acid and bile reflux into the esophagus were not detected by pH and bilirubin monitoring, respectively, in 6 patients after placement of the EMS with an anti-reflux mechanism for the stricture in the gastroesophageal junction. The median survival period of all patients after EMS placement was 123 days. The median survival period of 7 patients with radiotherapy only after EMS placement was 138 days and that of 17 patients with radiotherapy before EMS placement was 60 days, which was shorter than that of the former (p<0.05). On the other hand, the median survival period after hospital admission due to dysphagia of these 7 patients was longer than that of 17 patients with radiotherapy only before EMS placement, although, the difference was not significant. Conclusion: EMS with an antireflux mechanism is not commercially available in Japan and approval is urgently required. The indication of radiotherapy associated with EMS placement is to be studied further.  相似文献   
6.
We report the development of a serodiagnostic method for Mycobacterium avium complex (MAC) disease with an enzyme immunoassay (EIA) with the MAC-specific glycopeptidolipid (GPL) core as the antigen. In this study, we confirmed by EIA that the GPL core antibody was in the sera of immunocompetent patients with MAC disease. The EIA for quantifying the GPL core antibody was evaluated as a clinical tool for serodiagnosis of pulmonary MAC disease. A significant increase in GPL core antibodies (immunoglobulins G, A, and M) was detected in sera of patients with MAC pulmonary diseases when they were compared to patients who were colonized with MAC, patients with Mycobacterium kansasii disease or tuberculosis, and healthy subjects. The sensitivities and specificities of the GPL core-based EIA for diagnosis of MAC pulmonary disease were 72.6% and 92.2%, respectively, for IgG, 92.5% and 95.1%, respectively, for IgA, and 78.3% and 91.0%, respectively, for IgM. The best sensitivity and specificity were obtained by measuring immunoglobulin A antibodies against GPL core antigen. The level of GPL core antibodies reflected disease activity, since it decreased in cured MAC patients who had responded to chemotherapy. Measurement of serum antibodies against GPL core is useful for both diagnosis and assessment of disease activity in MAC disease of the lung.  相似文献   
7.
8.
Dehydrochlorinated poly(vinylidene chloride) proved to be a conjugated polyene-polyene polymer. Shock compression of the polymer formed a large portion of graphite and trace amounts of diamond and of an unknown carbon. The unknown carbon belongs to the hexagonal crystal system and possesses the cell dimension α0 = 0.338 nm. A comparison with known carbynes was made in terms of the crystalline parameters.  相似文献   
9.
One hundred and thirty-four patients with vasoocclusive diseases were retrospectively tested for three kinds of antiphospholipid antibody (aPL). The mean age at onset of the disease in 58 patients with aPL was 43 years old. Seventeen, 11, and 9 patients were positive for the aCL IgA, IgM, and IgG isotypes, respectively. The rates of anti-phospholipid syndrome (APS) in patients with arterial (n=94), venous (n= 31), or both arterial and venous (n=9) occlusion were 45%, 29%, and 78%, respectively.The rates of APS in patients with autoimmune disease (n=13), thromboangiitis obliterans (TAO) (n= 36), arteriosclerosis obliterans (ASO) with lower leg involvement (n=8) or aortic arch syndrome (n=5), Raynaud's syndrome (n=15), aortitis syndrome (n= 13), ischemic heart disease (IHD) with young onset (n =12), and bilateral leg deep venous thrombosis (DVT) (n=10) were 77%, 46%, 13%, 80%, 40%, 62%, 33%, and 70%, respectively. The cumulative patency rate for reconstructive surgery in patients (n=13) with aCL was found to be considerably lower than that in those without aCL (n=13). From these results it was concluded that IgA was the most valuable aCL isotype for the diagnosis of APS and that aPL should be examined in patients with double-vessel occlusion, autoimmune disease, bilateral leg DVT, aortic arch syndrome, TAO, Raynaud's syndrome, or IHD with young onset. Furthermore, prophylaxis for graft failure is more strongly recommended for patients with aCL than for those without it.  相似文献   
10.
Ocular allergic reactions and inflammatory cascades in the eye involve various arachidonic acid metabolites. One such metabolite, leukotriene B4 (LTB4) was detected in bovine lenses after incubation in Tyrode's solution and analyzed by reverse phase and normal phase high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). LTB4, a product of the lipoxygenase pathway has a chemotactic potency, and may play an important role in the inflammatory cascade. Our results demonstrate the capacity of the bovine lens to synthesize LTB4. It is possible that LTB4 synthesized in lenses under some conditions plays an important role in ocular inflammatory and allergic reactions.  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