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   9245篇
  免费   459篇
  国内免费   60篇
耳鼻咽喉   166篇
儿科学   213篇
妇产科学   125篇
基础医学   1161篇
口腔科学   331篇
临床医学   567篇
内科学   2295篇
皮肤病学   263篇
神经病学   846篇
特种医学   272篇
外科学   1128篇
综合类   52篇
一般理论   1篇
预防医学   327篇
眼科学   114篇
药学   805篇
中国医学   65篇
肿瘤学   1033篇
  2023年   47篇
  2022年   96篇
  2021年   139篇
  2020年   93篇
  2019年   111篇
  2018年   168篇
  2017年   132篇
  2016年   147篇
  2015年   160篇
  2014年   195篇
  2013年   272篇
  2012年   438篇
  2011年   465篇
  2010年   255篇
  2009年   216篇
  2008年   437篇
  2007年   508篇
  2006年   500篇
  2005年   539篇
  2004年   497篇
  2003年   459篇
  2002年   446篇
  2001年   307篇
  2000年   277篇
  1999年   247篇
  1998年   147篇
  1997年   94篇
  1996年   90篇
  1995年   96篇
  1994年   96篇
  1993年   81篇
  1992年   190篇
  1991年   160篇
  1990年   188篇
  1989年   149篇
  1988年   145篇
  1987年   158篇
  1986年   126篇
  1985年   138篇
  1984年   99篇
  1983年   76篇
  1982年   43篇
  1980年   43篇
  1979年   64篇
  1978年   40篇
  1977年   35篇
  1975年   32篇
  1974年   40篇
  1972年   34篇
  1971年   31篇
排序方式: 共有9764条查询结果,搜索用时 15 毫秒
101.
A 53-year-old woman had shown repeated, partial responses to chemotherapy for large, multiple liver metastases of sigmoid colon cancer. After a partial response to 5-fluorouracil plus leucovorin therapy, an 89.7% reduction of the 5-fluorouracil-resistant metastatic tumor was achieved by giving CPT-11 (irinotecan) at a dose of 100 mg/body per week. We suggest that CPT-11 should be recommended as an effective second-line treatment for unresectable liver metastases of colon cancer, after 5-fluorouracil-based chemotherapy.  相似文献   
102.
Objectives: Because several serum studies of vitamin D metabolites have produced equivocal results on their relation to prostate cancer risk, the purpose of this study is to evaluate this association further.Methods: A nested case-control study in a cohort of 3,737 Japanese-American men examined from 1967 to 1970 was conducted in Hawaii (United States). At the time of examination, a single blood specimen was obtained, and the serum was frozen. After a surveillance period of over 23 years, 136 tissue-confirmed incident cases of prostate cancer were identified. Their stored sera and those of 136 matched controls were measured for the following: 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, calcium, phosphorus, and parathyroid hormone.Results: There were no notable differences between cases and controls in their median serum levels of the five laboratory measurements. Odds ratios (OR) for prostate cancer, based on the quartiles of serum levels in controls, were also determined. The ORs for the highest quartiles relative to the lowest were 0.8 (95 percent confidence interval [CI] = 0.4-1.8) for 25-hydroxyvitamin D and 1.0 (CI = 0.5-2.1) for 1,25-dihydroxyvitamin D.Conclusion: It is possible that the lack of sufficient numbers of study subjects with low vitamin D levels affected the results. Nonetheless, the findings suggest that there is a lack of a strong association between vitamin D and prostate cancer.  相似文献   
103.
104.
105.
We have reported that excess soybean treatment and iodine deficiency synergistically interact, resulting in remarkable induction of thyroid hyperplasias in rats. In the present study, modifying effects of excess soybean and iodine-deficient diets were investigated in the post-initiation phase of N-bis(2-hydroxypropyl)nitrosamine [DHPN]-initiated thyroid tumorigenesis in rats. AIN-93G in which casein was replaced with gluten was used as a basal diet to avoid possible iodine contamination. In Experiment 1, F-344 rats of both sexes were sc injected with DHPN at a dose of 2800 mg/kg body weight and then fed a diet containing 0%, 0.8%, 4%, or 20% defatted soybean for 12 weeks, with proportional replacement of gluten by soybean flour. Although no thyroid proliferative lesions were found in any group, the absolute thyroid weights were significantly (p < 0.01) elevated with the 20% soybean treatment. In Experiment 2, after similar sc injection of DHPN, rats were fed a basal diet or a diet containing 20% soybean under iodine normal or deficient conditions for 12 weeks. Soybean feeding to both sexes under iodine deficient but not normal conditions dramatically enhanced the development of thyroid follicular adenomas (p < 0.01) and adenocarcinomas (p < 0.05), in good agreement with decrease in thyroxine and increase in thyroid-stimulating hormone. Thus co-exposure to excess soybean and iodine deficiency results in synergistic promotion of DHPN-initiated thyroid tumorigenesis in rats, of which mechanisms appear to primarily involve effects on serum hormone levels.  相似文献   
106.
PURPOSE: Transitional cell carcinoma (TCC) of the urinary tract is a chemosensitive tumor. Most deaths from TCC of the urinary tract are caused by metastasis, which is resistant to conventional chemotherapy. Frequent sites of metastases from TCC of the urinary tract are regional lymph nodes, liver, lung, and bone. Of these distant metastases, bone metastasis is consistently resistant to cisplatin-based conventional chemotherapy. Therefore, in this study, we investigated whether or not a newly developed minodronate, YM529, could prevent osteolytic bone metastasis of human TCC and also enhance the effect of docetaxel in a bone tumor model of athymic nude mice. EXPERIMENTAL DESIGN: In the present study, we evaluated the effect of in vitro treatment with minodronate and/or docetaxel on the proliferation by cell count, the induction of apoptosis by terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay, and the biological activity of osteoclast by pit formation assay in human bladder cancer cell line, UMUC-14, and mouse osteoclast cells. In vivo, we examined the effect of minodronate in a bone tumor model of athymic nude mice, in which the percutaneous intraosseal injection in the tibia of UMUC-14, leads to osteolytic bone tumor, as a bone metastasis model. To examine whether or not minodronate could inhibit tumorigenicity and enhance the effect of the chemotherapeutic agent, docetaxel, we gave minodronate i.p. and/or docetaxel i.p. to nude mice 3 days after an intraosseal tumor implantation. Moreover, proliferation and the induction of apoptosis of cancer cells and osteoclasts in bone tumors were determined by immunohistochemistry and the TUNEL assay. RESULTS: In vitro: In vitro treatment with docetaxel inhibited proliferation and resorption pit-forming activity and induced apoptosis of mouse osteoclast cells and UMUC-14 cells. In vitro treatment with minodronate inhibited proliferation and activity and induced apoptosis of mouse osteoclast cells but not UMUC-14 cells. The treatment with minodronate enhanced the inhibition of proliferation and activity by docetaxel in osteoclasts. In vivo: In vivo combination therapy with docetaxel and minodronate significantly reduced the tumor incidence compared with the control (P < 0.05) and also growth of intraossal TCC in athymic nude mice compared with the control (P < 0.001), single therapy with docetaxel (P < 0.01), and minodronate (P < 0.05). Drug-induced body weight loss was not significantly different in any treatment group. Therapy with minodronate significantly enhanced inhibition of proliferation by docetaxel in osteoclasts of bone tumors compared with the control (P < 0.01), single therapy with docetaxel (P < 0.01), and minodronate (P < 0.05). CONCLUSIONS: These studies indicate that combination therapy with minodronate and docetaxel may be beneficial in patients with bone metastasis of human TCC in the urinary tract.  相似文献   
107.
Although still controversial, iron deficiency has been indicated as one of the risk factors for developing neuroleptic-induced extrapyramidal symptoms (EPSs), including akathisia, dystonia, and neuroleptic malignant syndrome. Here we report our experience of iron supplementation and alternating neuroleptics for treating Parkinsonism in a schizophrenic female patient having severe iron deficient anemia.  相似文献   
108.
Three new triterpenoids, 3alpha,27-dihydroxylup-20(29)-en-28-oic acid methyl ester, 3alpha-acetoxy-27-hydroxylup-20(29)-en-28-oic acid methyl ester, and 3alpha-acetoxyolean-12-ene-27,28-dioic acid 28-methyl ester, were isolated from the roots of Peganum nigellastrum along with four known lupene-type triterpenoids. The structures of the new triterpenoids were determined by NMR spectroscopic means. The new triterpene, 3alpha, 27-dihydroxylup-20(29)-en-28-oic acid methyl ester is a DNA topoisomerase II inhibitor (IC(50) = 8.9 microM/mL).  相似文献   
109.
In order to determine whether 5-[bis(carboxymethyl) amino]-2-carboxy4-cyano-3-thiopheneacetic acid distrontium salt (S12911-2) inhibits bone resorption by acting on the differentiation and/or function of osteoclasts, its effects were assessed on the 1,25-dihydroxyvitamin D(3)-induced expression of carbonic anhydrase II and vitronectin receptor in chicken bone marrow cells, and on the resorbing activity of authentic rat osteoclasts cultured on bone slices. S12911-2 dose-dependently inhibited, after a 6-day exposure, the expression of carbonic anhydrase II and vitronectin receptor in stimulated osteoclasts (46% and 40%, respectively, at 10(-3) M Sr(2+), P<0.05). A pre-incubation of bone slices with S12911-2 induced a dose-dependent inhibition of bone resorbing activity from 32% at 10(-4) M Sr(2+) to 66% at 10(-3) M Sr(2+) (P<0.05 in each case). A continuous incubation (10(-3) M Sr(2+)) induced a greater inhibition of bone resorbing activity (73%, P<0.05). The inhibition of bone resorption obtained specifically with S12911-2 is related to an inhibition of the differentiation and resorbing activity of the osteoclasts.  相似文献   
110.
BackgroundCoronary tomography angiography (CTA) has been mainly used for chest pain evaluation in low-risk patients, and few data exist regarding patients at intermediate risk.ObjectiveTo evaluate the performance of serial measures of sensitive troponin and CTA in intermediate-risk patients.MethodsA total of 100 patients with chest pain, TIMI risk scores of 3 or 4, and negative troponin were prospectively included. All patients underwent CTA and those with coronary stenosis ≥ 50% were referred to invasive coronary angiography. Patients with coronary lesions <50% were discharged and contacted 30 days later by a telephone call to assess clinical outcomes. Outcomes were hospitalization, death, and myocardial infarction at 30 days. The comparison between methods was performed by Kappa agreement test. The performance of troponin measures and CTA for detecting significant coronary lesions and clinical outcomes was calculated. Results were considered statistically significant when p < 0.05.ResultsCoronary stenosis ≥ 50% on CTA was found in 38% of patients and significant coronary lesions on coronary angiography were found in 31 patients. Two clinical events were observed. Kappa agreement analysis showed low agreement between troponin measures and CTA in the detection of significant coronary lesions (kappa = 0.022, p = 0.78). The performance of CTA for detecting significant coronary lesions on coronary angiography or for predicting clinical events at 30 days was better than sensitive troponin measures (accuracy of 91% versus 60%).ConclusionCTA performed better than sensitive troponin measures in the detection of significant coronary disease in patients with chest pain and intermediate risk for cardiovascular events.  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