全文获取类型
收费全文 | 840篇 |
免费 | 61篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 6篇 |
儿科学 | 41篇 |
妇产科学 | 7篇 |
基础医学 | 77篇 |
口腔科学 | 65篇 |
临床医学 | 82篇 |
内科学 | 113篇 |
皮肤病学 | 8篇 |
神经病学 | 53篇 |
特种医学 | 192篇 |
外科学 | 47篇 |
综合类 | 74篇 |
预防医学 | 49篇 |
眼科学 | 4篇 |
药学 | 41篇 |
中国医学 | 24篇 |
肿瘤学 | 23篇 |
出版年
2024年 | 3篇 |
2022年 | 6篇 |
2021年 | 3篇 |
2020年 | 7篇 |
2019年 | 3篇 |
2018年 | 19篇 |
2017年 | 15篇 |
2016年 | 14篇 |
2015年 | 12篇 |
2014年 | 30篇 |
2013年 | 53篇 |
2012年 | 53篇 |
2011年 | 43篇 |
2010年 | 48篇 |
2009年 | 36篇 |
2008年 | 35篇 |
2007年 | 52篇 |
2006年 | 19篇 |
2005年 | 11篇 |
2004年 | 8篇 |
2003年 | 2篇 |
2002年 | 5篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 14篇 |
1998年 | 57篇 |
1997年 | 49篇 |
1996年 | 36篇 |
1995年 | 23篇 |
1994年 | 26篇 |
1993年 | 23篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 18篇 |
1988年 | 22篇 |
1987年 | 20篇 |
1986年 | 13篇 |
1985年 | 21篇 |
1984年 | 7篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 10篇 |
1979年 | 1篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 9篇 |
1975年 | 5篇 |
1954年 | 1篇 |
排序方式: 共有906条查询结果,搜索用时 11 毫秒
1.
目的:观察转染癌基因的骨髓基质干细胞在体外分化情况,为肝细胞癌的细胞源研究提供实验依据。方法:实验于2003-05/2004-06在南方医科大学药理教研室实验室完成。①两步法获取大鼠肝细胞,梯度离心法分离大鼠骨髓基质干细胞。②单基因转染是单独将c-myc或K-ras癌基因瞬时转染大鼠骨髓基质干细胞,6孔培养板中培养,24h后荧光显微镜下观察骨髓基质干细胞转染结果。双基因转染步骤相同,只是将c-myc和K-ras癌基因同时转染大鼠骨髓基质干细胞。③c-myc癌基因转染组、K-ras癌基因转染组、双癌基因转染组常规培养,加入含体积分数为0.1胎牛血清的DMEM培养基,于37℃、体积分数为0.05的CO2孵箱培养,每24h半量更换培养液。④c-myc癌基因转染 肝细胞组、K-ras癌基因转染 肝细胞组、双癌基因转染 肝细胞组将已转染癌基因的骨髓基质干细胞,置于叠加的培养板半透膜的上方(细胞密度均为1×105个/cm2),再将肝细胞置于半透膜的下方(每孔细胞密度为3×105/cm2)进行共培养,其余步骤同常规培养。⑤通过反转录聚合酶式反应和细胞免疫组化检测骨髓基质干细胞分化情况。结果:①癌基因转染24h骨髓基质干细胞检测结果:单独转染c-myc或K-ras癌基因的细胞,其绿色荧光蛋白呈均匀一致分布;双基因转染的细胞,绿色荧光蛋白呈点片状分布。②各组骨髓基质干细胞向肿瘤细胞分化检测结果:c-myc癌基因转染组、K-ras癌基因转染组、双癌基因转染组的骨髓基质干细胞,均未向肿瘤细胞分化;c-myc癌基因转染 肝细胞组、K-ras癌基因转染 肝细胞组、双癌基因转染 肝细胞组的骨髓基质干细胞,均向肝细胞癌发展;空白对照组骨髓基质干细胞细胞均为阴性。此外,双癌基因转染 肝细胞组的骨髓基质干细胞分化增殖迅速,反转录聚合酶式反应和免疫组化检测发现,培养第7天出现甲胎蛋白表达,并迅速增加,而第7天出现的白蛋白和细胞角蛋白18表达迅速减弱,第14天消失。结论:转染癌基因的骨髓基质干细胞,在向肝细胞诱导的条件下,部分癌基因可以使干细胞分化为肝癌细胞;多癌基因转染时,更易于使干细胞分化为肝癌细胞。 相似文献
2.
酵母菌药用乳糖酶制备新方法 总被引:3,自引:0,他引:3
目的:建立一种简易的从酵母菌制备克鲁维酵母乳糖酶的方法.方法:在30L发酵罐中进行发酵,用对羟基苯甲酸酯进行细胞破壁,用超微过滤方法浓缩破壁液.结果:乳糖酶的收率可达到每毫升发酵液含11.4 ONPG单位.从酵终细胞中释放乳糖酶可达70%,每毫升牛奶中加入1.2 ONPG单位制备的液态乳糖酶可使牛奶中的乳糖水解率达到70%. 相似文献
3.
目的:系统评价我国小切口复位内固定术(MIPPO)与切开复位内固定治疗胫骨远端骨折的疗效与安全性。方法计算机检索中国知网(CNKI:2003年9月-2013年5月)、万方数据库(2003年9月-2013年5月)、维普数据库(2003年9月-2013年5月),中国生物医学数据库及超星电子图书。手工检索国内近五年来发表于《中华骨科杂志》、《中国矫形外科杂志》及《临床骨科杂志》等各骨科杂志及相关杂志的相关文献。收集所有相关 MIPPO与切开复位内固定治疗胫骨远端骨折的随机对照试验及半随机对照试验,采用 Cochrane协作网提供的软件 RevMan5.0进行系统评价。结果共纳入12篇随机对照试验及半随机对照试验,共733例患者,纳入研究质量评价结果为 B级10篇,C级2篇。系统评价结果显示,与切开复位内固定组相比,MIPPO 组术中失血量少[SMD=-4.46,95%CI(-5.87,-3.05),P <0.05];骨折愈合时间短[SMD=-1.54,95%CI(-2.02,-1.06),P<0.05];术后优良率高[RR=1.22,95%CI(1.13,1.32),P <0.05],但两组手术时间比较差异无统计学意义。结论采用 MIPPO术治疗胫骨远端骨折具有明显的优势,值得临床推广。但由于该系统评价尚存在一定的局限性,故需要大量严格的、大样本量的、多中心性的,并且采用正确的随机、盲法、分配隐藏以及对失访与退出的患者进行正确的意向性分析(ITT分析)等文献研究来进一步论证。 相似文献
4.
5.
6.
Permanent impairment of embryo development by hydrosalpinges 总被引:6,自引:9,他引:6
Recent reports suggest a deleterious effect of hydrosalpinges on pregnancy
outcome for in-vitro fertilization (IVF) and improvement following surgical
treatment. We compared the effect of hydrosalpinx on pregnancy outcome in
286 patients having 348 IVF cycles and followed the development of
untransferred embryos for 7 days to determine if hydrosalpinges affect
oocyte quality or embryo development. The delivery rate per retrieval was
significantly lower for patients with hydrosalpinx, but was restored by
surgical treatment to that of patients without hydrosalpinx. However, the
implantation rate per embryo transferred and normal blastulation of
untransferred embryos, which were significantly decreased in patients with
hydrosalpinx, and growth arrest and degeneration of untransferred embryos,
which were significantly increased compared to patients without
hydrosalpinx, were not restored by surgical treatment of hydrosalpinges. We
conclude that surgical treatment of hydrosalpinges decreases early
pregnancy loss and improves pregnancy outcome, possibly by diminishing
reversible deleterious effects exerted on the endometrium. As we have seen
in our laboratory, hydrosalpinges may have a permanent negative influence
on ovarian function, follicular development and oocyte quality since
implantation of transferred embryos and normal blastulation of
untransferred embryos remain low, and in-vitro growth arrest and
degeneration remain high despite surgical treatment of hydrosalpinges.
相似文献
7.
Endothelin receptor expression in human decidua 总被引:3,自引:1,他引:3
Kohnen G; Campbell S; Irvine GA; Church HJ; MacLachlan F; Titterington M; Cameron IT 《Molecular human reproduction》1998,4(2):185-193
The endothelins are signalling peptides that act via two receptors, ET(A)
and ET(B). In the human endometrium, endothelin receptors have been
demonstrated in glands and stroma and have been shown to vary during the
course of the menstrual cycle. The present study was undertaken to
determine whether or not expression of endothelin receptors changes during
pregnancy or after administration of exogenous progestagens. The expression
of the receptors was correlated with the appearance of basement membrane
components during decidualization of the endometrial stroma. Decidual
specimens (n = 15) were obtained during the first trimester of pregnancy
and 10 at term. Sixteen pairs of endometrial biopsies were obtained from
women with menorrhagia before and after exposure to exogenous progestagens.
A total of 15 hysterectomy specimens were used as controls for the
expression of stromal basement membrane proteins in the absence of
decidualization. Autoradiography was carried out with selective ligands for
ET(A) ([125I]-PD 151242) and ET(B) ([125I]-BQ3020). The distribution of
ligand binding was then compared with the distribution of laminin alpha2
light chain and collagen IV. ET(A), ET(B), laminin alpha2 light chain, and
collagen IV were expressed in stromal decidual cells in the first trimester
of pregnancy. ET(B) was also found on endometrial glandular epithelium.
Quantitative macro-autoradiography and multiple regression analysis
demonstrated a highly significant positive correlation (P < 0.001)
between expression of ET(B) and laminin alpha2 light chain. In the third
trimester qualitative examination suggested a reduction of ET(A) in the
stroma. Progestagen-induced decidua exhibited a similar pattern to that
found in first trimester decidua. This study has demonstrated up-regulation
of ET(B) during the progesterone- dependent process of decidualization and
suggests a paracrine or autocrine role for endothelins in the decidua.
相似文献
8.
9.
GA McCarthy B Kampmann V Novelli RF Miller DE Mercey D Gibb 《Archives of disease in childhood》1996,74(5):455-457
AIDS related Kaposi's sarcoma is commonly seen in homosexual men, only occasionally in men and women with heterosexually acquired HIV, and extremely rarely in children. The case of an HIV infected mother and her vertically infected child who both developed visceral Kaposi's sarcoma is reported. It is proposed that the putative Kaposi's sarcoma agent may also be transmitted vertically. 相似文献
10.
Extracorporeal membrane oxygenation (ECMO) is a life support technique based on modifications of heart-lung bypass technology. It is used to support severe but potentially reversible pulmonary or cardiopulmonary failure. There is increasing use of the technique for neonates and a return of interest in its use for adults. The number of non-neonatal paediatric patients receiving pulmonary support with ECMO worldwide is, however, small, and survival rates average less than 50%. Initial experience in 15 patients aged 3 months to 5 years with a high survival and low morbidity is reported. 相似文献