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   6896篇
  免费   631篇
  国内免费   42篇
耳鼻咽喉   109篇
儿科学   199篇
妇产科学   113篇
基础医学   922篇
口腔科学   215篇
临床医学   633篇
内科学   1427篇
皮肤病学   141篇
神经病学   599篇
特种医学   237篇
外国民族医学   1篇
外科学   985篇
综合类   49篇
预防医学   498篇
眼科学   142篇
药学   465篇
中国医学   29篇
肿瘤学   805篇
  2023年   29篇
  2022年   32篇
  2021年   181篇
  2020年   112篇
  2019年   220篇
  2018年   250篇
  2017年   170篇
  2016年   175篇
  2015年   218篇
  2014年   272篇
  2013年   318篇
  2012年   389篇
  2011年   418篇
  2010年   255篇
  2009年   221篇
  2008年   342篇
  2007年   350篇
  2006年   308篇
  2005年   309篇
  2004年   272篇
  2003年   247篇
  2002年   236篇
  2001年   186篇
  2000年   216篇
  1999年   172篇
  1998年   85篇
  1997年   70篇
  1996年   53篇
  1995年   56篇
  1994年   61篇
  1993年   60篇
  1992年   112篇
  1991年   119篇
  1990年   109篇
  1989年   128篇
  1988年   84篇
  1987年   89篇
  1986年   67篇
  1985年   55篇
  1984年   63篇
  1983年   31篇
  1982年   46篇
  1981年   40篇
  1980年   29篇
  1979年   46篇
  1977年   30篇
  1976年   34篇
  1974年   22篇
  1972年   21篇
  1971年   27篇
排序方式: 共有7569条查询结果,搜索用时 312 毫秒
11.
SETTING: Tuberculosis (TB) is frequent in human immunodeficiency virus (HIV) infected patients, but its treatment is hampered by adverse events and paradoxical reactions. OBJECTIVE: To examine the impact of HIV infection and other factors on the risk and spectrum of adverse events related to anti-tuberculosis treatment in a prospective cohort study conducted between January 2003 and August 2004. RESULTS: Of 105 patients treated for TB, 30 were HIV-infected. The overall incidence of adverse events was 122.5 +/- 18.5 per 100 patient-years (py) and the incidence of severe adverse events was 45.2 +/- 11.3/100 py. Age >50 years (OR 2.2, 95%CI 1.01-4.8, P = 0.046) and HIV infection (OR 3.9, 95%CI 2.1-7.5, P < 0.001) were independently associated with a higher risk of adverse events. Hepatitis (30.5/100 py) and neuropathy (28.6/100 py) were the most frequent adverse events. Hepatitis C virus infection was associated with hepatitis (OR 4.2, 95%CI 1.2-15.0, P = 0.028) and neuropathy with HIV infection (OR 3.8, 95%CI 1.1-13.7, P = 0.040). CONCLUSION: Adverse reactions to anti-tuberculosis drugs are frequent. HIV infection and age >50 years are factors associated with such reactions, while hepatitis C virus infection is a risk factor for hepatitis.  相似文献   
12.
13.
BACKGROUND: The role of local excision for pT2 distal rectal cancer has been challenged because of the observation of high rates of lymph node metastases and local failure. However, neoadjuvant chemoradiation therapy (CRT) has led to increased local disease control and significant tumor downstaging, possibly decreasing rates of lymph node metastases. In this setting, a possible role for local excision of ypT2 has been suggested. METHODS: A total of 401 patients with distal rectal cancer underwent neoadjuvant CRT. Tumor response assessment was performed after at least 8 weeks from CRT completion. One hundred and twelve patients with complete clinical response were not immediately operated on and were excluded from the study, and 289 patients with incomplete clinical response were managed by radical surgery. Patients with final pathological stage ypT2 were analyzed to determine the risk of unfavorable pathological features that could represent unacceptable risk for local failure after local excision. RESULTS: Eighty-eight (30%) patients had ypT2 rectal cancer. Final ypT status was not associated with pretreatment radiological staging (p = 0.62). ypT status was significantly associated with the risk of lymph node metastases, risk of perineural and vascular invasion, and recurrence (p = 0.001). Lymph node metastases were present in 19% of patients with ypT2 rectal cancer. The risk of lymph node metastases in ypT2 was associated with the presence of perineural invasion (47% vs 4%; p = <0.001), vascular invasion (59% vs 6%; p < 0.001), and decreased mean interval CRT surgery (12 vs 18 weeks; p < 0.001), but not with mean tumor size (3.2 vs 3.1 cm; p = 0.8). Disease-free and overall survival rates were significantly better for patients with ypT2N0 (p = 0.02 and 0.006, respectively). Fifty-five (63%) patients with ypT2 had at least one unfavorable pathological feature for local excision (lymph node metastases, vascular or perineural invasion, mucinous type or tumor size >3 cm). CONCLUSION: Lymph node metastases were present in 19% of patients with ypT2 and were significantly associated with poor overall and disease-free survival rates. The risk of lymph node metastases could not be predicted by radiological staging or tumor size. Radical surgery should be considered the standard treatment option for ypT2 rectal cancer after CRT.  相似文献   
14.
Three high-amylose rice varieties, IR42, IR36, and IR62, with similar chemical composition including amylose content (26.7-27.0%), were cooked under the same conditions and tested for in vitro digestibility as well as blood glucose and insulin responses in healthy human volunteers. The starch-digestion rate and the glycemic and insulin responses were the highest in IR42, followed by IR36 and, then IR62. The differences were not due to unabsorbed carbohydrate but were related to their physicochemical properties, such as gelatinization temperature, minimum cooking time, amylograph consistency, and volume expansion upon cooking. When the three varieties were cooked for their minimum cooking time, they had the same degree of gelatinization and their starch-digestion rates and glycemic responses were similar. We conclude that amylose content alone is not a good predictor of starch-digestion rate or glycemic response. Rice varieties with similar high-amylose contents can differ in physicochemical (gelatinization) properties and this, in turn, can influence starch digestibility and blood glucose response.  相似文献   
15.
16.
17.
A monoclonal antibody raised by immunization of BALB/c mice with erythrocytic stages of Plasmodium vivax was shown to react with asexual erythrocytic stages of P. chabaudi. The cross-reactivity molecules are antigens of 200 and 148 kDa in P. vivax and of 190 and 70 kDa in P. chabaudi. Immunofluorescence studies of the erythrocytic stages of P. vivax and P. chabaudi indicated that expression of these antigens increased as the parasites' developed from the ring stage to the schizont stage. In the mature trophozoites of P. chabaudi, immunoelectron microscopy revealed clusters of antigen distributed in the cytoplasm of the parasitized erythrocyte. In the schizont, packets of antigen were found associated with the parasitophorous vacuole and the cytoplasm of the infected host cell. Received: 19 March 1996 / Accepted: 28 August 1996  相似文献   
18.
19.
Serum levels of testosterone, dihydrotestosterone, and follicle-stimulating and luteinizing hormones were determined prospectively in 59 patients with carcinoma of the prostate treated curatively with external beam radiotherapy. Hormone levels were determined before the initiation of therapy and up to 2 years following completion of therapy. Testosterone levels remained unchanged but dihydrotestosterone levels decreased slightly. Follicle-stimulating and luteinizing hormone levels increased significantly during therapy and remained elevated for up to 2 years after therapy. These findings are consistent with low dose irradiation of the testis.  相似文献   
20.
We studied 733 cadaveric renal transplant patients (747 transplants) under cyclosporin immunosuppression, to: (i) establish the risk profile for acute renal failure (ARF) after renal transplantation in a unit using many sub-optimal donors; (ii) assess the long-term prognostic relevance of ARF; and (iii) explore the synergistic prognostic significance of delayed graft function and acute rejection during the early post-transplant period. Transplanting from a non-heart-beating or elderly donor, protracted cold ischaemia, haemodialysis immediately before transplant surgery, poor HLA matching, and grafting to a hypersensitized recipient without residual renal function, all independently predicted delayed graft function. This delay had no detrimental effect on patient or graft survival, but prolonged ARF was associated with increased mortality from infection. Late markers of graft dysfunction (poor graft function, proteinuria, hypertension) were highly prevalent among grafts affected by ARF, specially in prolonged ARF. Delayed graft function and early acute rejection showed a definite, albeit not strong, additive impact on late graft survival, and also on the prevalence of late markers of graft dysfunction.   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