全文获取类型
收费全文 | 1963篇 |
免费 | 128篇 |
国内免费 | 52篇 |
专业分类
儿科学 | 2篇 |
妇产科学 | 223篇 |
基础医学 | 259篇 |
口腔科学 | 1篇 |
临床医学 | 93篇 |
内科学 | 32篇 |
皮肤病学 | 10篇 |
神经病学 | 9篇 |
特种医学 | 33篇 |
外科学 | 927篇 |
综合类 | 227篇 |
预防医学 | 116篇 |
眼科学 | 1篇 |
药学 | 90篇 |
中国医学 | 113篇 |
肿瘤学 | 7篇 |
出版年
2024年 | 4篇 |
2023年 | 13篇 |
2022年 | 33篇 |
2021年 | 69篇 |
2020年 | 53篇 |
2019年 | 53篇 |
2018年 | 51篇 |
2017年 | 43篇 |
2016年 | 66篇 |
2015年 | 58篇 |
2014年 | 95篇 |
2013年 | 102篇 |
2012年 | 90篇 |
2011年 | 89篇 |
2010年 | 100篇 |
2009年 | 81篇 |
2008年 | 77篇 |
2007年 | 87篇 |
2006年 | 113篇 |
2005年 | 75篇 |
2004年 | 66篇 |
2003年 | 73篇 |
2002年 | 53篇 |
2001年 | 51篇 |
2000年 | 39篇 |
1999年 | 32篇 |
1998年 | 21篇 |
1997年 | 29篇 |
1996年 | 38篇 |
1995年 | 34篇 |
1994年 | 40篇 |
1993年 | 22篇 |
1992年 | 21篇 |
1991年 | 35篇 |
1990年 | 34篇 |
1989年 | 30篇 |
1988年 | 23篇 |
1987年 | 14篇 |
1986年 | 18篇 |
1985年 | 15篇 |
1984年 | 20篇 |
1983年 | 17篇 |
1982年 | 6篇 |
1981年 | 19篇 |
1980年 | 11篇 |
1979年 | 13篇 |
1978年 | 7篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1972年 | 2篇 |
排序方式: 共有2143条查询结果,搜索用时 15 毫秒
1.
BackgroundArtificial insemination with the husband’s semen (AIH) is an economical and noninvasive method of infertility treatment. However, AIH’s pregnancy rate is much lower than in vitro fertilization (IVF) as its multiple and complex uncertainty factors. Semen quality has been one of the main factors which affect the pregnancy outcome of AIH.MethodsThe relevant parameters of 1,142 AIH cycles were retrospectively studied, including the general parameters and the semen quality parameters among clinical pregnancy, biochemical pregnancy, non-pregnancy group, age, infertility duration, infertility type, body mass index (BMI), cycle count, morphology in previously semen examination, and semen quality parameters on the day of AIH.ResultsThe statistically significant difference was only found on processed total non-forward and non-motile sperm count (N-TFMSC). The mean processed N-TFMSC in the biochemical pregnancy group was 6.37±4.27 million, significantly higher than the other two groups (vs. 4.40±3.15 million or vs. 4.48±3.60 million, P<0.05). The study was then divided into two groups according to processed N-TFMSC, Group 1 ≤5.0 million, and Group 2 >5.0 million. A statistical increase in biochemical pregnancy rate was observed when the processed N-TFMSC was >5.0 million (2.72% vs. 0.90%).ConclusionsProcessed N-TFMSC may be one of the independent factors on AIH’s outcome; it should be given equal attention the same as processed total forward motile sperm count (TFMSC). 相似文献
2.
Objectives
For individuals not on antiretroviral therapy, the risk of heterosexual transmission of HIV appears negligible when blood plasma (BP) viral loads are <1500 HIV‐1 RNA copies/mL. It is not clear whether this observation can be extrapolated to individuals on highly active antiretroviral therapy (HAART). Because of differential tissue penetration, antiretroviral drug concentrations may be sufficient to maintain an undetectable viral load in the BP yet not achieve adequate levels to suppress HIV in the genital tract. Therefore, we wanted to correlate HIV viral loads and drug concentrations in semen plasma (SP) and BP.Methods
Thirty‐three men were included. All were on combination antiretroviral therapy with an undetectable BP viral load for at least 1 year. Blood and semen samples were collected within 2 h of each other and tested for HIV RNA by the NucliSens QT (bioMerieux, St Laurent, QC, Canada) method; drug concentrations were determined by liquid chromatography tandem mass spectrometry.Results
Two of the 33 patients (6.1%) with BP viral loads below detection had time‐matched HIV viral loads in SP ≥700 copies/mL. Both patients were on efavirenz, the SP concentrations of which were ≤10% of the levels in BP and well below the minimal therapeutic drug monitoring target concentration required to suppress HIV.Conclusions
Because, at least in part, of poor drug penetration into the genital tract, an undetectable HIV viral load in the BP does not guarantee an undetectable viral load in semen. In view of this, caution should be taken in concluding that patients on HAART with suppressed viraemia are sexually non‐infectious. 相似文献3.
R. Rybar P. Markova Z. Veznik L. Faldikova M. Kunetkova A. Zajicova V. Kopecka & J. Rubes 《Andrologia》2009,41(3):141-149
Damage to the genetic component of spermatozoa seems to play the main role in a majority of cases where current approaches fail to reveal the specific cause of male infertility. In this study, we compared semen quality in men assigned to two defined groups: men from couples with unexplained infertility – idiopathic infertility (A) and young men with no experiences of infertility (B). All samples were examined by standard ejaculate analysis and sperm chromatin structure assay (SCSA). Sperm chromatin damage was significantly higher in men from group A than in those from group B. Similar results were obtained by comparison of men from group A (all men were normozoospermic) with normozoospermic men from group B. According to these results, we can suppose that chromatin disorders may be the causal factor of subfertility or infertility in some of these men. No evidence for a strong association between chromatin disorders and standard parameters of ejaculates was found. We failed to confirm a relationship between smoking and sperm quality in men from any of the investigated groups. SCSA is a method that facilitates the identification of infertile men who otherwise show normal semen variables. 相似文献
4.
Receiver operating characteristic curves and accuracy parameters were computed for traditional sperm characteristics (concentration, motility, morphology) and the number of peroxidase negative cells, and the concentration of adenosine triphosphate (ATP) in semen from populations of fertile and infertile men, and men who achieved a pregnancy after varicocele treatment. The percentage and concentration per millilitre of spermatozoa with rapid linear progressive motility, and the ATP concentration, provided the best discrimination between fertile and treated fertile from infertile men. The misclassification rate was higher for sperm morphology, total progressive motility and viability, whereas sperm concentration and the total sperm count per ejaculate had the worst discriminating power. The number of peroxidase negative cells per 100 spermatozoa was highly specific in identifying men who achieved pregnancy after varicocele treatment. The lower limit of normality of sperm characteristics was remarkably different between fertile men and men achieving pregnancy after treatment or during infertility work-up. 相似文献
5.
C. L. R. BARRATT A. ROBINSON R. C. SPENCER† G. R. KINGHORN A. WHITE P. E. HARRISON E. KESSOPOULOU I. D. COOKE 《International journal of andrology》1990,13(5):361-368
The relationship between asymptomatic urethral infection and seminal white blood cells, as detected using the peroxidase enzyme system, was examined. Eighty-four semen donors were tested. Twenty-four (29%) were diagnosed as having an active urethral genital infection. There was no statistical relationship between the total number of concentrations of peroxidase-positive cells and a urethral genital infection. Further studies should concentrate on the subtypes of seminal leucocytes and their surface receptors using monoclonal antibodies. 相似文献
6.
HERMAN TOURNAYE RONNY JANSSENS PAUL DEVROEY RK VAN STEIRTEGHEM 《International journal of andrology》1994,17(1):1-8
In order to evaluate the effects of pentoxifylline on sperm motility and longevity, a controlled in-vitro study was conducted on normozoospermic donor semen samples using the Cellsoft automated system for sperm motility analysis. After incubation and selection, pentoxifylline was found to improve the recovery of spermatozoa and to increase their velocity. In the subgroup of progressively motile spermatozoa, curvilinear velocity was also enhanced. It is concluded that pentoxifylline has an effect on the vigour, but not on the pattern, of sperm motion. Pentoxifylline did not improve the motility characteristics of senescent spermatozoa in normozoospermic sperm samples. Sperm survival, as shown by supra-vital staining, and motility longevity both decreased with time after pentoxifylline treatment. 相似文献
7.
本文应用放射免疫测定的方法检测了13例输精管结扎后(平均15.3年,平均年龄50岁)的男性精浆双氢睾酮和睾酮的浓度,另取同年龄组男性13例作为对照。结果表明,精浆睾酮在结扎组(374.54p/ml)和正常对照组(315.64Pg/ml)中没有明显差异,而结扎组精浆中双氢睾酮(46.21pg/ml)却明显低子对照组(184.27pg/ml(p<0.01)。作者认为,输精管结扎对精浆DHT有长期影响,这可能是其对前列腺增生过程产生抑制作用的原因之一。 相似文献
8.
Improvement in quality of cryopreserved human spermatozoa by swim-up before freezing 总被引:4,自引:0,他引:4
F. PÉREZ-SÉNCHEZ T. G. COOPER C. H. YEUNG E. NIESCHLAG 《International journal of andrology》1994,17(3):115-120
Selecting a population of spermatozoa by the swim-up technique yields, after freezing and thawing, a population of cells that contains proportionally more spermatozoa which are morphologically normal, fewer spermatozoa with damaged tail membranes, and a greater percentage of progressively motile spermatozoa with greater velocities and amplitudes of head displacement than those obtained after freezing and thawing the same semen samples in the normal way. This pattern was found for the semen from 10 patients and five volunteers. However, the cells selected by swim-up were as susceptible to the stresses caused by freezing and thawing as unselected spermatozoa in the original semen sample, and the improvement came from the better quality of the initial sample. 相似文献
9.
Solveig B. Larsen Aleksander Giwercman Marcello Spanò Jens P. Bonde The ASCLEPIOS Study Group 《Reproductive toxicology (Elmsford, N.Y.)》1998,12(6):391-589
It was hypothesized that occupational exposure to pesticides during a spraying season causes changes in semen quality that might be detected in a longitudinal study. We analyzed the within-person changes in semen quality and reproductive hormones across a spraying season in groups of farmers using and not using pesticides. A total of 248 men collected two semen samples (participation rate: 32%). The median sperm concentration declined significantly from the first to the second sample in both groups, but there was no statistical difference in the decline between the two groups, unadjusted or adjusted. Only minor changes were found in sperm morphology, vitality, motility, sperm chromatin denaturation (SCSA), and reproductive hormones, and the differences in changes between the two groups were nonsignificant, or, in the opposite direction to the expected. There was no relation between the changes in sperm parameters in relation to pesticide exposure variables. In conclusion, use of pesticides by Danish farmers is not a likely cause of short-term effects on semen quality and reproductive hormones. 相似文献
10.
不同免疫抑制剂对肾移植患者精子参数的影响 总被引:2,自引:0,他引:2
目的:研究不同免疫抑制剂对肾移植患者精子运动功能的影响。方法:20例肾移植患者应用以普乐可复(FK506+霉酚酸酯+泼尼松)、17例应用环孢素(CsA+硫唑嘌呤+泼尼松)为主的免疫抑制治疗方案,15例正常男性为对照组。采用计算机辅助的精子分析系统分别检测精子活率、运动参数(前向运动百分率、直线速度VSL、曲线速度VCL、平均路径速度VAP)和精子形态。结果:3组精子活率[(81.7±5.7)%、(79.4±6.8)%、(83.8±6.0)%]、VCL[(24.1±8.6)%、(23.9±4.4)%、(24.8±4.2)%]和VAP[(19.7±6.6)%、(18.6±2.9)%、(21.0±4.0)%]差异均无显著性(P>0.05);FK506组的精子前向性运动百分率[(46.4±8.1)%]和VSL[(15.4±4.6)%]均显著高于CsA组[(33.3±6.4)%、(10.2±2.4)%],畸形率[(67.8±5.7)%]显著低于CsA组[(80.1±5.6%](P<0.05)。结论:FK506和霉酚酸酯的联合应用,有助于肾移植患者精子运动功能及形态的恢复。 相似文献