全文获取类型
收费全文 | 475篇 |
免费 | 41篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 17篇 |
妇产科学 | 8篇 |
基础医学 | 112篇 |
口腔科学 | 17篇 |
临床医学 | 44篇 |
内科学 | 100篇 |
皮肤病学 | 12篇 |
神经病学 | 9篇 |
特种医学 | 99篇 |
外科学 | 44篇 |
综合类 | 14篇 |
预防医学 | 22篇 |
眼科学 | 1篇 |
药学 | 25篇 |
肿瘤学 | 10篇 |
出版年
2022年 | 3篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 7篇 |
2016年 | 7篇 |
2015年 | 9篇 |
2014年 | 15篇 |
2013年 | 11篇 |
2012年 | 9篇 |
2011年 | 8篇 |
2010年 | 23篇 |
2009年 | 22篇 |
2008年 | 10篇 |
2007年 | 21篇 |
2006年 | 5篇 |
2005年 | 13篇 |
2004年 | 9篇 |
2003年 | 5篇 |
2002年 | 10篇 |
2001年 | 11篇 |
2000年 | 8篇 |
1999年 | 10篇 |
1998年 | 25篇 |
1997年 | 18篇 |
1996年 | 14篇 |
1995年 | 21篇 |
1994年 | 13篇 |
1993年 | 15篇 |
1992年 | 12篇 |
1991年 | 5篇 |
1990年 | 9篇 |
1989年 | 23篇 |
1988年 | 22篇 |
1987年 | 27篇 |
1986年 | 20篇 |
1985年 | 16篇 |
1984年 | 4篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1975年 | 8篇 |
1970年 | 4篇 |
1969年 | 2篇 |
1965年 | 3篇 |
1955年 | 2篇 |
排序方式: 共有535条查询结果,搜索用时 15 毫秒
1.
2.
3.
Perfluorochemicals as US contrast agents for tumor imaging and hepatosplenography: preliminary clinical results 总被引:3,自引:0,他引:3
Mattrey RF; Strich G; Shelton RE; Gosink BB; Leopold GR; Lee T; Forsythe J 《Radiology》1987,163(2):339-343
In animals, perfluorochemicals (PFCs) are effective ultrasound (US) contrast agents that produce hepatic, splenic, and tumor enhancement. The use of Fluosol-DA 20%, an emulsion of perfluorodecalin and perfluorotripropylamine, was studied in nine non-critically ill patients with cancer who had liver lesions. US studies without Fluosol were compared with studies obtained 24, 48, and 72 hours after Fluosol infusion. Vital signs and extensive laboratory analyses are performed before and after Fluosol infusion. Liver metastases from colonic, pancreatic, and gastric carcinoma exhibited rim or diffuse enhancement after a Fluosol dose of 1.6 g/kg or greater. Fluosol produced echogenic enhancement of the liver and spleen relative to kidney at a dose of 2.4 g/kg, allowing the detection of nonenhancing lesions. In addition, Fluosol at a dose of 1.6 g/kg or greater allowed detection of lesions not seen before contrast medium was administered in three of the seven patients studied. There was a mild increase in the level of serum glutamic oxaloacetic transaminase in two patients, one given 2.4 and the other 3.2 g/kg of Fluosol. Mild and transient allergic reactions without change in vital signs were experienced by two patients. 相似文献
4.
5.
6.
Cytotoxic T lymphocytes (CTL) recognize antigens derived from endogenously expressed proteins presented on the cell surface in the context of major histocompatibility complex (MHC) class I molecules. Because CTL are effective in antiviral and antitumor responses, the delivery of antigens to the class I pathway has been the focus of numerous efforts. Generating CTL by immunization with exogenous proteins is often ineffective because these antigens typically enter the MHC class II pathway. This review focuses on the usefulness of bacterial toxins for delivering antigens to the MHC class I pathway. Several toxins naturally translocate into the cytosol, where they mediate their cytopathic effects, and the mechanisms by which this occurs has been elucidated. Molecular characterization of these toxins identified the functional domains and enabled the generation of modified proteins that were no longer toxic but retained the ability to translocate into the cytosol. Thus, these modified toxins could be examined for their ability to carry peptides or whole proteins into the cytosolic processing pathway. Of the toxins studied—diphtheria, pertussis, Pseudomonas, and anthrax—the anthrax toxin appears the most promising in its ability to deliver large protein antigens and its efficiency of translocation. 相似文献
7.
8.
We have previously shown that natural killer (NK) cell activity against K562 tumor cells is severely depressed in thermal injury patients. In this study we have investigated whether the low NK cell activity present in peripheral blood lymphocytes (PBL) from thermal injury patients could be enhanced byin vitro culture with interleukin 2 (IL2) and whether PBL obtained from these patients could generate lymphokine-activated killer (LAK) cell activity against NK insensitive tumor targets. NK cell activity in PBL obtained from 12 different patients was greatly enhanced against K562 tumor cells afterin vitro culture with IL2 for 3 days. In contrast, PBL obtained from these patients and incubated with IL2 had little to no cytotoxic activity when measured against a number of NK-insensitive tumor targets. The failure of PBL obtained from thermal injury patients to generate LAK cell activity was observed regardless of the culture time or the amount of IL2 added to the cultures. PBL from thermal injury patients demonstrated reduced proliferative responses to IL2 and, more importantly, contained suppressor cells which could inhibit the generation of LAK cell activity of normal PBL obtained from control individuals. These results clearly show that in some thermal injury patients NK cell activity can be enhanced by IL2 but these patients are defective in their ability to generate LAK cell activity. 相似文献
9.
Pre-eclampsia, one of the most significant health problems inhuman pregnancy, complicates 6-7% of all gestations and is theleading cause of fetal growth retardation, infant morbidityand mortality, premature birth and maternal death. Recent researchimplicates free radicals in the pathophysiology of pre-eclampsia.This review covers the biochemistry of nitric oxide (NO) andpossible interactions with other free radicals. Studies in therat show that pregnancy is associated with enhanced productionand responsiveness to NO in both reproductive tissues and bloodvessels. Rats infused with NG-nitro-L-arginine methyl ester(L-NAME, a NO synthase inhibitor) have been used as an animalmodel of pre-eclampsia, and the effects of steroid hormoneson blood pressure in this model have been tested. Results suggestthat pre-eclampsia may be a state of NO deficiency. However,in humans there seem to be contradictions regarding the involvementof NO in maternal adaptation to pregnancy. It is suggested thatNO may be one of several systems that act in concert to maintaina symbiotic relationship between mother and fetus. However,the input of each system may be genetically determined. 相似文献
10.
Dohle GR; Ramos L; Pieters MH; Braat DD; Weber RF 《Human reproduction (Oxford, England)》1998,13(3):620-623
Male genital tract obstructions may result from infections, previous
inguinal and scrotal surgery (vasectomy) and congenital bilateral absence
of the vas deferens (CBAVD). Microsurgery can sometimes be successful in
treating the obstruction. In other cases and in cases of failed surgical
intervention, the patient can be treated by microsurgical or percutaneous
epididymal sperm aspiration (MESA, PESA) or testicular sperm extraction
(TESE) and intracytoplasmic sperm injection (ICSI). We present the results
of 39 ICSI procedures for obstructive azoospermia in 24 couples. The
aetiology of the obstruction was failed microsurgery in 11 patients, CBAVD
in nine and genital infections in four. Sperm retrieval was accomplished
via MESA in four cases, PESA in 18 cases and via TESE in 11 cases. TESE was
only applied when PESA failed to produce enough spermatozoa for
simultaneous ICSI. In six patients, the ICSI procedure was performed with
cryopreserved spermatozoa after an initial PESA procedure. Fertilization
occurred in 47% of the metaphase II oocytes; embryo transfer was performed
in 92% of procedures and resulted in a clinical pregnancy in 13/39
procedures. Ongoing pregnancy was achieved in 10/39 procedures. One
pregnancy was terminated early after prenatal investigation showed a
cytogenetic abnormality (47,XX+18, Edwards syndrome). The other nine
pregnancies resulted in the live birth of 10 children, without any
congenital abnormalities. Epididymal and testicular retrieved spermatozoa
were successfully used for ICSI to treat obstructive azoospermia, and
resulted in an ongoing pregnancy in 10 of 24 couples (41.6%) after 39 ICSI
procedures, a success rate of 25.6% per treatment cycle and of 27.7% per
embryo transfer.
相似文献