全文获取类型
收费全文 | 694篇 |
免费 | 49篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 58篇 |
儿科学 | 29篇 |
妇产科学 | 24篇 |
基础医学 | 70篇 |
口腔科学 | 14篇 |
临床医学 | 89篇 |
内科学 | 146篇 |
皮肤病学 | 28篇 |
神经病学 | 53篇 |
特种医学 | 70篇 |
外科学 | 94篇 |
综合类 | 16篇 |
预防医学 | 17篇 |
眼科学 | 7篇 |
药学 | 29篇 |
肿瘤学 | 13篇 |
出版年
2022年 | 2篇 |
2021年 | 11篇 |
2020年 | 13篇 |
2019年 | 16篇 |
2018年 | 15篇 |
2017年 | 23篇 |
2016年 | 18篇 |
2015年 | 13篇 |
2014年 | 23篇 |
2013年 | 42篇 |
2012年 | 36篇 |
2011年 | 35篇 |
2010年 | 36篇 |
2009年 | 33篇 |
2008年 | 43篇 |
2007年 | 36篇 |
2006年 | 36篇 |
2005年 | 37篇 |
2004年 | 29篇 |
2003年 | 18篇 |
2002年 | 20篇 |
2001年 | 18篇 |
2000年 | 15篇 |
1999年 | 9篇 |
1998年 | 19篇 |
1997年 | 23篇 |
1996年 | 24篇 |
1995年 | 17篇 |
1994年 | 11篇 |
1993年 | 14篇 |
1992年 | 8篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1971年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有757条查询结果,搜索用时 8 毫秒
1.
神经生长因子对小鼠突触体内Ca^2+水平的调节作用 总被引:4,自引:1,他引:3
观察了多次海马内微注射NGF对小鼠突触体内游离钙水平的影响,并在离体情况下观察NGF对EGTA和CaCl2分别造成突触体内低钙和高钙状态的调节作用。结果如下:(1)在体实验表明,一定剂量的NGF可显著降低老年小鼠海马突触体内游离钙水平(P<005);(2)离体实验表明,当突触体游离钙水平降低时,适当剂量的NGF具有升高游离钙水平的作用;而突触体内游离钙水平升高时,则NGF有降低游离钙水平的作用。提示NGF对游离钙水平的双向调节作用可能是NGF改善老年性记忆衰退的作用机制。 相似文献
2.
3.
MY Mancao LJ Sindel PH Richardson FM Silver 《Acta paediatrica (Oslo, Norway : 1992)》1996,85(1):118-120
Croup is an acute infectious illness usually occurring in children; it is characterized by brassy cough and stridor. The main pathogens include mainly parainfluenza and influenza viruses. Recently there have been reports of prolonged croup caused by the herpes simplex viruses. We report two cases of prolonged croup due to herpes simplex types 1 and 2. We also review and summarize the reported pediatric cases of herpetic croup. 相似文献
4.
Duncan WC; Illingworth PJ; Young FM; Fraser HM 《Human reproduction (Oxford, England)》1998,13(9):2532-2540
The molecular mechanisms involved in luteolysis are still unclear in the
primate. This study aimed to investigate the effect of induced luteolysis
on the ovarian luteinizing hormone (LH) receptor and the steroidogenic
enzyme, 3beta-hydroxysteroid dehydrogenase (3beta-HSD) in the marmoset
monkey. Luteolysis was induced in the mid-luteal phase either directly by
systemic prostaglandin F2alpha (PGF2alpha), or indirectly by LH withdrawal
using systemic gonadotrophin releasing hormone antagonist (GnRHant)
treatment. The LH receptor was studied by isotopic mRNA in-situ
hybridization and in-situ ligand binding and 3beta-HSD expression was
studied using isotopic mRNA in-situ hybridization and immunohistochemistry.
Induced luteolysis was associated with a reduction in the expression of LH
receptor (P < 0.0001) and 3beta-HSD mRNA, closely followed by a
reduction in the LH receptor (P < 0.05) and 3beta-HSD protein
concentrations within 24 h. There were no differences in the findings
whether luteolysis was induced with PGF2alpha or GnRHant. This study shows
that disparate mechanisms to induce luteolysis in the primate result in an
identical rapid loss of the LH receptor and 3beta-HSD. In conclusion,
induced luteolysis leads to rapid loss of the steroidogenic pathway in
luteal cells.
相似文献
5.
6.
7.
8.
Transition metal complexes containing vanadium IV have been shown to
modulate the cellular redox potential and catalyse the generation of
reactive oxygen intermediates (ROI). Since sperm function is exquisitely
susceptible to ROI, we examined the effects of stable chelate complexes of
vanadocenes on human sperm motility. We synthesized seven structurally
distinct chelate complexes of bis(cyclopentadienyl)vanadium(IV) with
bidentate ligands [i.e. vanadocene acetylacetonato monotriflate (VDacac),
vanadocene hexafluoro acetylacetonato monotriflate (VDHfacac), vanadocene
N-phenyl benzohydroxamato monotriflate (VDPH), vanadocene acethydroxamato
monotriflate (VDH), vanadocene catecholate (VDCAT), vanadocene bipyridino
ditriflate (VDBPY), and vanadocene dithiocarbamate monotriflate (VDDTC)],
and evaluated their spermicidal activity using computer-assisted sperm
analysis (CASA; Hamilton-Thorne). All seven chelate complexes of vanadocene
elicited potent spermicidal activity at micromolar concentrations (EC50
values: 3.9-106 microM) without affecting the sperm acrosome integrity. The
catecholate and acetylacetonate complexes of vanadocene were the most
active and the bipyridyl complex the least active with an order of efficacy
VDCAT > VDacac > VDDTC > VDPH > VDH > VDHfacac > VDBPY.
The spermicidal activity of chelate complexes of vanadocenes was rapid and
irreversible since the treated spermatozoa underwent apoptosis, as
determined by the flow cytometric analysis of mitochondrial membrane
potential, surface annexin V binding assay, in-situ nick-end labelling of
sperm nuclei, and confocal laser scanning microscopy. These results provide
unprecedented evidence that chelate complexes of vanadocene with bidentate
ligands have spermicidal and apoptosis inducing properties. These
vanadocene complexes, especially VDacac, may be useful as contraceptive
agents.
相似文献
9.
Rongières-Bertrand C Olivennes F Righini C Fanchin R Taïeb J Hamamah S Bouchard P Frydman R 《Human reproduction (Oxford, England)》1999,14(3):683-688
Natural cycles were abandoned in in-vitro fertilization (IVF) embryo transfer, due to premature luteinizing hormone (LH) surges--and subsequent high cancellation rates. In this study, we investigated the administration of a new gonadotrophin-releasing hormone antagonist (Cetrorelix) in the late follicular phase of natural cycles in patients undergoing IVF and intracytoplasmic sperm injection (ICSI). A total of 44 cycles from 33 healthy women [mean age 34.1 +/- 1.4 (range 26-36) years] were monitored, starting on day 8 by daily ultrasound and measurement of serum concentrations of oestradiol, LH, follicle stimulating hormone (FSH) and progesterone. When plasma oestradiol concentrations reached 100-150 pg/ml, with a lead follicle between 12-14 mm diameter, a single injection (s.c.) of 0.5 mg (19 cycles) or 1 mg (25 cycles) Cetrorelix was administered. Human menopausal gonadotrophin (HMG; 150 IU) was administered daily at the time of the first injection of Cetrorelix, and repeated thereafter until human chorionic gonadotrophin (HCG) administration. Four out of 44 cycles were cancelled (9.0%). No decline in follicular growth or oestradiol secretion was observed after Cetrorelix administration. A total of 40 oocyte retrievals leading to 22 transfers (55%) was performed. In 10 cycles (25%), no oocyte was obtained. Fertilization failure despite ICSI occurred in six cycles (15%). In two patients the embryo was arrested at the 2 pronuclear (PN) stage. The stimulation was minimal (4.7 +/- 1.4 HMG ampoules). A total of seven clinical pregnancies was obtained (32.0% per transfer, 17.5% per retrieval), of which five are ongoing. Thus, a spontaneous cycle and the GnRH antagonist Cetrorelix in single dose administration could represent a first-choice IVF treatment with none of the complications and risks of current controlled ovarian hyperstimulation protocols, and an acceptable success rate. 相似文献
10.
Olivennes F Fanchin R Lédée N Righini C Kadoch IJ Frydman R 《Human reproduction update》2002,8(2):117-128
Since the first birth after IVF, many scientific papers have been published on the technical aspects of the IVF procedure, but few studies have addressed the issue of the perinatal outcome of IVF pregnancies and of the children's development and well-being. A high rate of adverse outcome has been demonstrated in a large group of IVF pregnancies. Prematurity, low birth weight and perinatal mortality are higher than in the general population. The majority of these complications are related to multiple births, but they are also found in singleton pregnancies. An analysis of the multiple risk factors involved in these complications is needed. The infertile status of IVF patients clearly plays a role in the risk of adverse outcome. Age and parity may be important factors. The role of IVF itself has not been demonstrated convincingly. The effect of ovarian stimulation deserves further study. Most of the studies published on the follow-up of IVF children are reassuring, but it is clear that these studies are not sufficient to eliminate without doubt any adverse effects on the well-being of IVF children. All IVF pregnancies should be followed with great care, not because they are more precious than spontaneous pregnancies, but because they are exposed to an increased risk of complications. The main problem of IVF remains the high rate of multiple pregnancies, including twins. 相似文献