全文获取类型
收费全文 | 1521250篇 |
免费 | 117135篇 |
国内免费 | 6424篇 |
专业分类
耳鼻咽喉 | 18138篇 |
儿科学 | 49841篇 |
妇产科学 | 39915篇 |
基础医学 | 201697篇 |
口腔科学 | 38056篇 |
临床医学 | 134185篇 |
内科学 | 311251篇 |
皮肤病学 | 33083篇 |
神经病学 | 127747篇 |
特种医学 | 64958篇 |
外国民族医学 | 274篇 |
外科学 | 240684篇 |
综合类 | 34002篇 |
现状与发展 | 2篇 |
一般理论 | 437篇 |
预防医学 | 124943篇 |
眼科学 | 31116篇 |
药学 | 104102篇 |
5篇 | |
中国医学 | 2880篇 |
肿瘤学 | 87493篇 |
出版年
2018年 | 34687篇 |
2017年 | 27362篇 |
2016年 | 31570篇 |
2015年 | 15914篇 |
2014年 | 21629篇 |
2013年 | 31666篇 |
2012年 | 44488篇 |
2011年 | 60493篇 |
2010年 | 42985篇 |
2009年 | 35484篇 |
2008年 | 55956篇 |
2007年 | 60397篇 |
2006年 | 41534篇 |
2005年 | 41470篇 |
2004年 | 40779篇 |
2003年 | 40653篇 |
2002年 | 36848篇 |
2001年 | 66498篇 |
2000年 | 68453篇 |
1999年 | 56911篇 |
1998年 | 17043篇 |
1997年 | 15307篇 |
1996年 | 16171篇 |
1995年 | 16397篇 |
1994年 | 15241篇 |
1993年 | 14258篇 |
1992年 | 47233篇 |
1991年 | 45923篇 |
1990年 | 44195篇 |
1989年 | 41985篇 |
1988年 | 38870篇 |
1987年 | 38215篇 |
1986年 | 35958篇 |
1985年 | 34747篇 |
1984年 | 26450篇 |
1983年 | 22182篇 |
1982年 | 13920篇 |
1981年 | 12509篇 |
1980年 | 11797篇 |
1979年 | 23603篇 |
1978年 | 17126篇 |
1977年 | 14417篇 |
1976年 | 13229篇 |
1975年 | 13764篇 |
1974年 | 16166篇 |
1973年 | 15448篇 |
1972年 | 14226篇 |
1971年 | 13076篇 |
1970年 | 11951篇 |
1969年 | 11158篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
991.
992.
Functional characteristics of intraepithelial lymphocytes from mouse small intestine. III. Inability of intraepithelial lymphocytes to induce a systemic graft-versus-host reaction is because of failure to migrate in vivo.
下载免费PDF全文
![点击此处可从《Gut》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this study we have investigated whether addition of bone marrow accessory cells or concurrent administration of recombinant IL-2 would allow intraepithelial lymphocytes (IEL) to induce a systemic, lethal GvHR in irradiated hosts. In addition we have studied the ability of IEL to migrate into lymphoid tissues after intravenous injection and compared this with their locomotor capacity in vitro. 相似文献
993.
994.
995.
996.
997.
D J Chambers M V Braimbridge D J Hearse 《European journal of cardio-thoracic surgery》1987,1(2):80-90
The isolated perfused working rat heart model of cardiopulmonary bypass was used to assess whether (a) allopurinol pretreatment enhances resistance to normothermic (30 min) or hypothermic (4 h) ischemia; (b) addition of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) to cardioplegic and/or reperfusion solutions are protective; (c) any protective effects are additive. With normothermic ischemia, allopurinol pretreatment improved recovery of aortic flow from its control value of 25 +/- 3% to 48 +/- 6% (P less than 0.05). Similarly, SOD plus CAT used during both ischemia and reperfusion improved recovery of aortic flow from a control value of 28 +/- 4% to 48 +/- 6% (P less than 0.05). However, various combinations of the two types of intervention afforded no additive protection. Under hypothermic (21 degrees C) conditions, allopurinol pretreatment was not effective, whereas SOD and CAT added during ischemia and reperfusion improved recovery of aortic flow from its control value of 53 +/- 4% to 69 +/- 5% (P less than 0.05). This value was similar to allopurinol pretreatment and SOD plus CAT added during ischemia and reperfusion (69 +/- 6%: P less than 0.05). These results provide further evidence that reperfusion-induced free radical formation may adversely affect postischemic recovery of function. The absence of an additive effect suggests a common mechanism of action, which is likely to involve the free radical-generating enzyme xanthine oxidase; however, other mechanisms may exist. Our results further support the use of antifree radical intervention in conjunction with cardioplegia to protect the heart during ischemia and reperfusion. 相似文献
998.
Clinical data of 192 patients with breast cancer with a primary lesion of 2-5 cm (stage II according to the criteria recommended by the UICC) and with histopathologically confirmed positive axillary lymph nodes were analyzed. The patients were divided into three groups: 1) surgical excision alone; 2) surgery plus irradiation; and 3) surgery plus chemotherapy. It was shown that the 5-year survival rates for these groups were 40.5%, 61.0%, and 62.0%, respectively (P less than .05). 相似文献
999.
The 5-year results of a randomized trial of adjuvant radiation therapy after chemotherapy in breast cancer patients treated with mastectomy 总被引:4,自引:0,他引:4
K L Griem I C Henderson R Gelman D Ascoli B Silver A Recht R L Goodman S Hellman J R Harris 《Journal of clinical oncology》1987,5(10):1546-1555
The use of adjuvant radiation therapy in breast cancer patients treated with mastectomy and adjuvant chemotherapy has been controversial. In order to assess the necessity and effectiveness of adjuvant radiation therapy in this setting, we reviewed the results in 510 patients with T1-T3 tumors and pathologically positive nodes or tumors larger than 5 cm and negative nodes who were treated with adjuvant chemotherapy. Patients with four or more positive nodes or at least one positive apical node were randomized to receive either five or ten cycles of cyclophosphamide/Adriamycin (Adria Laboratories, Columbus, OH) (CA) and patients with one to three positive nodes or operable tumors larger than 5 cm and pathologically negative nodes were randomized to receive eight cycles of either cyclophosphamide, methotrexate, and 5-fluorouracil (5-FU) (CMF) or methotrexate and 5-FU (MF) chemotherapy. Two hundred six of these patients were subsequently rerandomized to receive either no further treatment or adjuvant radiotherapy. Thirty-five patients withdrew after randomization, including 34 who declined to receive radiotherapy. Radiation therapy consisted of 4,500 cGy in 5 weeks to the chest wall and appropriate draining lymph nodes. Median follow-up from chemotherapy randomization is 45 months for patients in the CA arm and 53 months for those in the CMF/MF arm. The crude rate of local failure (chest wall or draining lymph node areas) as first site of failure for patients randomized to receive chemotherapy only was 14%; for those randomized to receive both chemotherapy and radiotherapy it was 5% (P = .03). For patients in the CMF/MF arm, the rate of local failure as the first site of failure was nearly the same for patients randomized to chemotherapy only as for those randomized to adjuvant radiotherapy as well (5% v 2%). For patients in the CA arm, the crude rate of local failure was 20% for patients randomized to receive chemotherapy only, and 6% for those randomized to both types of adjuvant treatment (P = .03). Among the 43 patients treated with CA who actually received radiotherapy, there was only one local failure, compared with 12 local failures among the 59 patients (20%) who actually did not receive radiotherapy (P = .007). No significant difference was seen in disease-free survival or overall survival in either the CA or the CMF/MF arm between patients randomized to receive radiation therapy and those randomized to no further treatment.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
1000.
The aim of the study was to determine the effect of exogenous melatonin treatment on circulating prolactin levels in red deer. Melatonin was administered from 12 June 1984 (day 1) to lactating and non-lactating hinds in the feed daily at 1600 h, and to non-lactating hinds by a subcutaneous implant. Average concentrations (ng/ml) of prolactin in plasma taken serially over 15-h periods were significantly higher for untreated hinds than for melatonin-treated animals on day 15 whether lactating (66-133 v. 23-28, P less than 0.05) or non-lactating (28-174 v. 8-13, P less than 0.01), remained higher on day 36 (lactating: 41-152 v. 15-21, P less than 0.05; non-lactating: 21-50 v. 1-7, P less than 0.001) but had decreased to similar levels on day 72 (lactating: 5-24 v. 7-17; non-lactating: 2-9 v. 0-4). The advanced reduction in plasma prolactin for all melatonin-treated hinds was associated with an advanced onset of seasonal breeding activity. 相似文献