全文获取类型
收费全文 | 390篇 |
免费 | 22篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 14篇 |
妇产科学 | 5篇 |
基础医学 | 39篇 |
口腔科学 | 24篇 |
临床医学 | 54篇 |
内科学 | 113篇 |
皮肤病学 | 3篇 |
神经病学 | 6篇 |
特种医学 | 74篇 |
外科学 | 19篇 |
综合类 | 18篇 |
预防医学 | 21篇 |
眼科学 | 1篇 |
药学 | 19篇 |
中国医学 | 1篇 |
肿瘤学 | 12篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 11篇 |
2015年 | 5篇 |
2014年 | 8篇 |
2013年 | 15篇 |
2012年 | 5篇 |
2011年 | 6篇 |
2010年 | 17篇 |
2009年 | 24篇 |
2008年 | 5篇 |
2007年 | 19篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 5篇 |
1998年 | 30篇 |
1997年 | 30篇 |
1996年 | 30篇 |
1995年 | 25篇 |
1994年 | 17篇 |
1993年 | 19篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 11篇 |
1989年 | 12篇 |
1988年 | 15篇 |
1987年 | 18篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1975年 | 3篇 |
排序方式: 共有424条查询结果,搜索用时 109 毫秒
121.
Embryo transfer--can we learn anything new from the observation of junctional zone contractions? 总被引:2,自引:6,他引:2
Lesny P; Killick SR; Tetlow RL; Robinson J; Maguiness SD 《Human reproduction (Oxford, England)》1998,13(6):1540-1546
To assess whether embryo transfer can alter junctional zone contractility,
we studied the effect of easy and difficult mock transfers in 14 oocyte
donors during in-vitro fertilization (IVF) cycles. An Echovist bolus (30
microl) was used to represent embryos and transfer medium. An 'easy'
transfer was judged to be an atraumatic insertion of the catheter without
touching the uterine fundus. A 'difficult' embryo transfer was mimicked by
deliberately touching the uterine fundus twice with the soft end of the
cannula. Transvaginal scan images were recorded, digitized and converted
into five times normal speed to allow us to evaluate junctional zone
contractility. Easy mock embryo transfers did not change endometrial
mechanical activity. Echovist remained in the upper part of the uterine
cavity and was not dispersed after 45 min. A difficult procedure generated
strong random waves in the fundal area and waves from fundus to cervix
which relocated the Echovist in six out of seven cases. We observed
movements of the transfer bolus from the upper part of the uterus towards
the cervix (four cases) and into Fallopian tubes (two patients). Our study
confirms that the mechanical activity of the uterus is capable of
relocating intrauterine embryos and that this activity depends on physical
stimulation. Junctional zone contractions can be implicated in cases of
IVF/embryo transfer failure or ectopic gestation.
相似文献
122.
Genetic deficiency of the purine salvage enzyme adenosine deaminase (ADA)
results in varying degrees of immunodeficiency, ranging from neonatal onset
Severe Combined Immunodeficiency (SCID) to an adult onset immunodeficiency
disorder. Multiple different mutations have now been identified in these
immunodeficient patients. Additional mutations, initially identified in
healthy individuals, abolish ADA in erythrocytes but retain 10-80% of
activity in non-erythroid cells ('partial deficiency mutations'). In
general, severity of disease correlates inversely with the amount of
residual ADA expressed by the mutant enzymes and directly with the
accumulation of the toxic metabolites deoxyATP and deoxyadenosine. We
report two newly identified mutations (Y97C and L106V), both carried on the
same allele of an immunodeficient patient who was diagnosed prenatally and
successfully transplanted with haploidentical bone marrow. Based on the
ability of mutant cDNAs to express ADA in vitro , the L106V mutation
resulted in activity similar to 'partial' mutations (30% of normal) while
the Y97C mutation resulted in detectable but markedly reduced activity
(1.5% of normal). However, the presence of both mutations on the same
allele virtually abolished detectable enzyme activity. Analysis of the
crystallographic structure of ADA to understand the marked deleterious
effect of the Y97C mutation suggested a previously unappreciated role of
salt bridges in the catalytic mechanism of ADA. The patient was also
heteroallelic for a previously described deletion of the promoter and exon
1. Testing of additional patients in whom we had not identified a mutation
on the second allele revealed presence of this deletion in three of four
patients tested. This deletion is therefore relatively common, accounting
for 10% of almost 100 chromosomes studied by this and other laboratories,
but is easily missed by currently used methods of mutation detection.
Lastly, the finding of two mutations on the same allele that interact to
reduce residual enzyme function emphasizes hazards in evaluating potential
genotype-phenotype correlations in individuals analyzed only for the
presence of single specific mutations.
相似文献
123.
Great progress has been achieved during the last 20 years inthe field of ovulation induction in patients with polycysticovary syndrome (PCOS). Clomiphene citrate remains the firstline of treatment for all anovulatory women with PCOS, sincein properly selected patients the cumulative pregnancy rateapproaches that in normal women. Human urinary gonadotrophinshave been used extensively for ovulation induction but the developmentof low-dose regimens has opened a new era in the managementof anovulation related to PCOS. This article discusses the mainadvantages and disadvantages of the principal methods and regimenscurrently used for ovulation induction in patients with PCOSincluding clomiphene citrate, gonadotrophins, pulsatile gonadotrophin-releasinghormone (GnRH) and GnRH agonists. It also discusses new drugsdiscovered recently, particularly recombinant gonadotrophinsand GnRH antagonists, and provides some thoughts regarding theiruse in future protocols. Finally, based on the discovery ofnew ovarian substances which specifically control luteinizinghormone (LH) secretion, this article develops assumptions onpossible implications of these substances in the pathophysiologyof PCOS and their potential use in the management of the syndrome. 相似文献
124.
Somatic mutations are frequent and increase with age in human kidney epithelial cells 总被引:6,自引:0,他引:6
Martin GM; Ogburn CE; Colgin LM; Gown AM; Edland SD; Monnat RJ Jr 《Human molecular genetics》1996,5(2):215-221
We have used a primary cloning assay to determine the frequency of 6-
thioguanine (TG)-resistant tubular epithelial cells in kidney tissue from
72 human donors ranging in age from 2 to 94 years. The frequency of
TG-resistant mutants ranged from approximately 5 x 10(-5) for donors in the
first decade of life to approximately 2.5 x 10(-4) for donors in the eighth
and later decades of life. Two different statistical analyses indicated
that this increase in mutant frequency is exponential with age. We also
observed a 2-fold higher TG-resistant mutant frequency in nephrectomy
kidneys containing a coincident renal carcinoma. DNA sequence analyses
revealed HPRT gene mutations in each of 14 TG-resistant mutants from seven
unrelated donors. Thirteen of these 14 mutants resulted from independent
mutational events. These results suggest that somatic mutations are common
in renal--and perhaps in other human--epithelia, and thus could play an
important role in the genesis of age-associated disease.
相似文献
125.
The predictive value of the zona-free hamster egg penetration test in relation to in-vitro fertilization at various insemination concentrations 总被引:2,自引:0,他引:2
Zainul Rashid MR; Fishel SB; Thornton S; Hall JA; Ndukwe G; Aloum M; Fleming SD 《Human reproduction (Oxford, England)》1998,13(3):624-629
The aim of the study was to evaluate the predictive value of the zona- free
hamster egg penetration test (ZHEPT) for success in in-vitro fertilization
(IVF) at various insemination concentrations ranging between 0.1 and
>0.6 x 10(6)/ml. The ZHEPT was assessed using sperm samples from 87
couples undergoing IVF treatment. A similar test was simultaneously
performed on the same semen sample following ionophore induction of the
acrosome reaction (ZHEPTii test). Both the tests were poorly correlated
with the fertilization rate of IVF at all the insemination concentrations
except at >0.6 x 10(6)/ml, when there was good correlation between the
ZHEPTii test and the fertilization rate. Following exclusion of two cases
with an oocyte problem, further statistical analysis revealed that both the
ZHEPT and ZHEPTii tests were poorly correlated with fertilization rate in
IVF in this treatment group. This study suggests that the ZHEPT (with and
without ionophore induction of the acrosome reaction) has a poor predictive
value for the success of fertilization in IVF treatment at any insemination
concentration.
相似文献
126.
127.
M Tarchouli B Ait Idir N Bouhabba SD El Jaouhari T Salaheddine Y Hnach A Zentar 《Annals of the Royal College of Surgeons of England》2021,103(3):e77
Trichobezoar is a rare condition that occurs mostly in young women with psychiatric disorders such as trichotillomania and trichophagia. We report the case of a giant gastric trichobezoar in a 21-year-old woman who presented with chronic abdominal pain, vomiting and weight loss. Abdominal examination revealed a large epigastric mass. Endoscopic and imaging findings were highly suggestive of a gastric trichobezoar. Surgical extraction of the huge hair mass was successfully performed through an open gastrotomy. Postoperatively, history of a neglected chronic depression with suicidal ideation was diagnosed. Consequently, the patient was referred to the psychiatric department for mental healthcare, to prevent trichobezoar recurrences. 相似文献
128.
A Pro51Ser mutation in the COCH gene is associated with late onset autosomal dominant progressive sensorineural hearing loss with vestibular defects 总被引:14,自引:0,他引:14
de Kok YJ; Bom SJ; Brunt TM; Kemperman MH; van Beusekom E; van der Velde- Visser SD; Robertson NG; Morton CC; Huygen PL; Verhagen WI; Brunner HG; Cremers CW; Cremers FP 《Human molecular genetics》1999,8(2):361-366
We analysed a Dutch family with autosomal dominant non-syndromic
progressive sensorineural hearing loss and mapped the underlying gene
defect by genetic linkage analysis to a 11.0 cM region overlapping the
DFNA9 interval on chromosome 14q12-q13. Clinically, the Dutch family
differs from the original DFNA9 family by a later age at onset and a more
clearly established vestibular impairment. A gene that is highly and
specifically expressed in the human fetal cochlea and vestibule, COCH
(previously described as Coch5B2 ), was mapped to the DFNA9 critical
region. Sequence analysis revealed a 208C-->T mutation in the COCH gene,
resulting in a Pro51Ser substitution in the predicted protein in all
affected individuals of the family but not in unaffected family members and
200 control individuals. The same mutation was also identified in three
apparently unrelated families with a similar phenotype, suggesting the
presence of a Dutch founder mutation. The function of COCH is unknown but
several characteristics of the protein point to a structural role in the
extracellular matrix. The mutant serine at position 51 is situated between
cysteines and possibly interferes with proper COCH protein folding or its
interaction with extracellular matrix proteins.
相似文献
129.
130.