全文获取类型
收费全文 | 14753篇 |
免费 | 1150篇 |
国内免费 | 377篇 |
出版年
2023年 | 108篇 |
2022年 | 217篇 |
2021年 | 383篇 |
2020年 | 296篇 |
2019年 | 345篇 |
2018年 | 414篇 |
2017年 | 360篇 |
2016年 | 478篇 |
2015年 | 762篇 |
2014年 | 810篇 |
2013年 | 1008篇 |
2012年 | 1146篇 |
2011年 | 1068篇 |
2010年 | 676篇 |
2009年 | 536篇 |
2008年 | 759篇 |
2007年 | 723篇 |
2006年 | 651篇 |
2005年 | 595篇 |
2004年 | 539篇 |
2003年 | 519篇 |
2002年 | 419篇 |
2001年 | 333篇 |
2000年 | 335篇 |
1999年 | 292篇 |
1998年 | 133篇 |
1997年 | 105篇 |
1996年 | 81篇 |
1995年 | 60篇 |
1994年 | 98篇 |
1993年 | 69篇 |
1992年 | 172篇 |
1991年 | 151篇 |
1990年 | 135篇 |
1989年 | 156篇 |
1988年 | 125篇 |
1987年 | 115篇 |
1986年 | 109篇 |
1985年 | 104篇 |
1984年 | 72篇 |
1983年 | 75篇 |
1982年 | 47篇 |
1979年 | 54篇 |
1977年 | 77篇 |
1976年 | 47篇 |
1975年 | 43篇 |
1974年 | 56篇 |
1973年 | 42篇 |
1971年 | 40篇 |
1969年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 468 毫秒
31.
32.
T. Zaccheo D. Giudici E. Di Salle 《The Journal of steroid biochemistry and molecular biology》1993,44(4-6):677-680
The antitumor effect of exemestane (FCE 24304), an irreversible aromatase inhibitor, given alone or in combination with tamoxifen, was investigated in rats with 7, 12-dimethylbenzanthracene (DMBA)-induced mammary tumors. The compounds were given once daily, 6 days a week for 4 weeks. Exemestane, given at the dose of 20 mg/kg/day s.c., induced 26% complete (CR) and 18% partial (PR) tumor regressions, compared to 0% CR and 6% PR observed in controls. Tamoxifen, given at 1 mg/kg/day p.o., induced 16% CR and 13% PR. The combined treatment caused 41% CR and 16% PR, thus resulting in a higher antitumor effect than either single treatment. The apperance of new tumors was reduced by each single treatment and almost totally prevented by the combined treatment. Serum prolactin (PRL) levels, assayed 4 h after the last dose, were unchanged in the group treated with the combination, whereas tamoxifen alone caused a slight increase of serum PRL. These results indicate that estrogen deprivation through aromatase inhibition and estrogen receptor antagonism causes a better inhibition of DMBA-induced mammary tumors than either treatment modality alone. 相似文献
33.
D Di Lorenzo G Ruggeri C Iacobello S Belloli M Gion D T Zava S Ghielmi A Albertini 《The International journal of biological markers》1991,6(3):151-158
A radioreceptor assay (RRA) for the determination of total estrogen activity, was set up and used to assess the possible presence of exogenous molecules with estrogen activity in serum; a comparison was made with the specific radioimmunoassay (RIA) for the endogenous estrogen 17-B estradiol (17-B-E2). The assay was first performed on sera from healthy people taking estrogens in the form of oral contraceptives or lotions for local application whose total estrogenic activity in the blood was assumed to be abnormal. The assay was then performed on serum from 98 patients with early breast cancer and 20 patients with metastasis, not undergoing hormone therapy. A higher estrogen activity was found in 2.5% of sera compared to the activity found using the RIA method which is specific for endogenous estrogen 17-B-E2, the RRA/17-B-E2 ratio being higher than 3. Increased estrogen activity was found in 10% serum samples from digoxin treated cardiopathic patients, with an RRA/17-B-E2 ratio ranging from 4.4 to 20. The RRA assay could prove useful for showing up exogenous estrogen activity from various sources (drugs, food) in sera of people in whom estrogen stimulation could be potentially dangerous (i.e. in patients with hormone-sensitive tumors). This exogenous activity could support a certain degree of neoplastic stimulation and, therefore, unfavourably condition the patients' therapeutic response. 相似文献
34.
35.
A retrovirus carrying the polyomavirus middle T gene induces acute thrombocythemic myeloproliferative disease in mice. 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A Fusco G Portella M Grieco G Tajana G Di Minno N Polli A Pinto 《Journal of virology》1988,62(1):361-365
Mice inoculated with an artificially constructed retrovirus carrying the middle T gene of polyomavirus develop acute myeloproliferative disease with severe thrombotic and hemorrhagic disorder and impaired platelet function. The megakaryocytic lineage appears to be a target for polyoma-murine leukemia virus infection and middle T gene expression. This newly described disease represents a unique model system for studying disorders of the megakaryocytic lineage. 相似文献
36.
37.
38.
Behavioural expression of D-1 receptor supersensitivity depends on previous stimulation of D-2 receptors 总被引:1,自引:0,他引:1
SKF 38393 (2 mg/kg s.c.), a reportedly selective D-1 agonist, failed to induce contralateral turning behaviour in naive rats bearing 12 days old unilateral 6-hydroxydopamine lesions. On the other hand strong contraversive turning in response to SKF 38393 was obtained if rats had been tested 2 or 7 days before with apomorphine (0.1 mg/kg s.c.) or with LY 171555 (0.2 mg/kg s.c.), a selective D-2 receptor agonist. Contraversive turning in response to SKF 38393 was blocked by a low dose (0.05 mg/kg s.c.) of the specific D-1 antagonist SCH 23390. The results indicate that the behavioural expression of D-1 receptor supersensitivity following lesion of dopaminergic neurons depends on previous exposure to a stimulation of D-2 receptors. 相似文献
39.
40.