首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   475篇
  免费   1篇
儿科学   1篇
妇产科学   148篇
基础医学   262篇
口腔科学   1篇
临床医学   9篇
内科学   32篇
神经病学   4篇
特种医学   1篇
外科学   2篇
综合类   1篇
预防医学   10篇
药学   4篇
肿瘤学   1篇
  2020年   1篇
  2019年   1篇
  2018年   1篇
  2014年   5篇
  2013年   2篇
  2012年   22篇
  2011年   33篇
  2010年   15篇
  2009年   7篇
  2008年   20篇
  2007年   24篇
  2006年   26篇
  2005年   29篇
  2004年   38篇
  2003年   42篇
  2002年   31篇
  2001年   9篇
  2000年   10篇
  1999年   10篇
  1998年   10篇
  1997年   15篇
  1996年   11篇
  1995年   20篇
  1994年   14篇
  1993年   12篇
  1992年   14篇
  1991年   5篇
  1990年   6篇
  1989年   15篇
  1988年   11篇
  1987年   6篇
  1986年   4篇
  1985年   3篇
  1984年   2篇
  1983年   2篇
排序方式: 共有476条查询结果,搜索用时 15 毫秒
1.
Either a percutaneous-transvesical, a transvaginal, or a perurethral-transvesical approach can be used for oocyte recovery under ultrasound guidance in an in vitro fertilization and embryo transfer program. After having experienced these three different approaches in our program, we preferentially used the perurethral-transvesical approach as our routine technique for oocyte recovery under ultrasound guidance. We feel that this method is easier to perform and also carrier less risk for contamination. From January to December 1986, 186 oocyte retrievals under ultrasound guidance were performed. In 7 cases no oocytes were found despite normal ovarian stimulation. A total of 767 oocytes was collected; the fertilization rate was 71.8%. Forty pregnancies were achieved (21.5% per attempt or 27.7% per embryo replacement). Except for transient hematuria, no complications were observed.  相似文献   
2.
3.
The aim of the study was to determine whether a prior diagnostic testicle biopsy can predict success or failure of testicular sperm extraction (TESE) with intracytoplasmic sperm injection (ICSI) in patients with non-obstructive azoospermia caused by testicular failure, and what is the minimum threshold of sperm production in the testis which must be surpassed for spermatozoa to reach the ejaculate. Forty- five patients with non-obstructive azoospermia caused by testicular failure underwent diagnostic testicle biopsy prior to a planned future TESE-ICSI procedure. The diagnostic testicle biopsy was analysed quantitatively, and correlated with the quantitative findings of spermatogenesis in patients with normal spermatogenesis, as well as with the results of subsequent attempts at TESE-ICSI. Men with non- obstructive azoospermia caused by germinal failure had a mean of 0-6 mature spermatids/seminiferous tubule seen on a diagnostic testicle biopsy, compared to 17-35 mature spermatids/tubule in men with normal spermatogenesis and obstructive azoospermia. These findings were the same for all types of testicular failure whether Sertoli cell only, maturation arrest, cryptorchidism, or post-chemotherapy azoospermia. Twenty-two of 26 men with mature spermatids found in the prior testis biopsy had successful retrieval of spermatozoa for ICSI, 12 of their partners became pregnant, and are either ongoing or delivered. The study suggests that 4-6 mature spermatids/tubule must be present in the testis biopsy for any spermatozoa to reach the ejaculate. More than half of azoospermic patients with germinal failure have minute foci of spermatogenesis which are insufficient to produce spermatozoa in the ejaculate. Prior diagnostic testicle biopsy analysed quantitatively (for the presence of mature spermatids) can predict subsequent success or failure with TESE-ICSI. Incomplete testicular failure may involve a sparse multi-focal distribution of spermatogenesis throughout the entire testicle, rather than a regional distribution. Therefore, it is possible that massive testicular sampling from many different regions of the testes may not be necessary for successful TESE-ICSI.   相似文献   
4.
A third-generation gonadotrophin-releasing hormone antagonist(Cetrorelix) was used during ovarian stimulation in 32 patientsundergoing assisted reproduction, in order to prevent the prematureluteinizing hormone (LH) surge. In all patients, ovarian stimulationwas carried out with two or three ampoules of human menopausalgonadotrophin (HMG), starting on day 2 of the menstrual cycle.In addition, 0.5 mg of Cetrorelix was administered daily fromday 6 of HMG treatment until the day of ovulation inductionby human chorionic gonadotrophin (HCG). A significant drop inplasma LH concentration was observed within a few hours of thefirst administration of Cetrorelix (P<0.005). Moreover, noLH surge was detected at any point in the treatment period inany of the 32 patients. A mean oestradiol concentration of 2122±935ng/1 was observed on the day of the HCG administration, indicatingnormal folliculogenesis. Like LH, progesterone concentrationalso dropped within a few hours of the first administrationof Cetrorelix (P< 0.005). A 0.5 mg daily dose of Cetrorelixprevented a premature LH surge in all the 32 patients treated.  相似文献   
5.
This case illustrates the possibility of obtaining oocytes that fertilize and cleave normally after the administration of a second ovulatory dose of human chorionic gonadotrophin (HCG) in a case of 'empty follicle syndrome'. The present patient underwent ovarian stimulation with gonadotrophin-releasing hormone analogue (GnRHa)/menotropin for intracytoplasmic sperm injection (ICSI). After the failure of the first oocyte retrieval, a second dose of HCG was administered to trigger ovulation. A total of 13 oocytes was retrieved during the second procedure and 11 good quality embryos were obtained (fertilization and cleavage rates of 92 and 91% respectively). No pregnancy was achieved after the replacement of three embryos. In a subsequent cycle stimulated with clomiphene citrate, three frozen- thawed embryos were replaced and a twin pregnancy was achieved. The patient delivered two healthy babies at term.   相似文献   
6.
Attempts to increase the probability of a successful pregnancyin in-vitro fertilization (IVF) treatment by increasing thenumber of embryos transferred automatically also increase theprobability of multiple pregnancies and their attendant risks.Even where the number of transferred embryos is limited to amaximum of three as in this and other centres, there is a highincidence of twins and triplets. The question therefore ariseswhether the number of transferred embryos should be furtherlimited to a maximum of two in cases where the prognosis isotherwise good. The only objection to this idea is a possiblelowering of pregnancy rate. The present study set out to investigatethis question. No significant lowering of pregnancy rate wasfound, so that limiting the number of transferred embryos totwo where the prognosis is otherwise good has now become standardpractice in our centre. A good IVF prognosis was defined bythe following criteria: first attempt for IVF, less than 37years old, and good embryo development. From 183 patients fulfillingthese criteria, 80 agreed to the transfer of two embryos (group1) and 103 opted for a triple transfer (group 2). Patient characteristicsand embryology results were similar in the two groups. In group1, 34 patients (42.5%) became pregnant and in group 2, 50 (48.5%).This difference is not significant. Similarly, twin pregnancyrates in both groups were high; eight twin pregnancies (23.5%)in group 1 and 12 (24%) in group 2. For the triplet pregnancyrate of 18% (nine triplet pregnancies) in group 2, there wasobviously no parallel in group 1. After thawing about half ofthe cryopreserved embryos and subsequently replacing them, preliminarycumulative pregnancy rates of 52.5% in group 1 and 53.4% ingroup 2 were obtained. Future results from cryopreservationshould provide relatively better outcomes for group 1 sinceall the patients in this group had at least one embryo frozenand fewer embryos replaced in the fresh cycle.  相似文献   
7.
Serum follicle stimulating hormone (FSH) is routinely measured when evaluating the infertile male for intracytoplasmic sperm injection (ICSI). However, among the sperm parameters, only its relationship with sperm concentration is well documented. Few investigations concern the relationship between FSH and sperm motility and morphology, and the results of ICSI. A retrospective study of 316 couples who underwent ICSI was carried out to determine the relationships between serum FSH concentrations in the male and (i) standard sperm parameters_(concentration, motility and morphology) and (ii) fertilization, cleavage, pregnancy and implantation rates after ICSI. There was an inverse correlation with sperm concentration and total motility but no relationship was found with progressive motility and sperm morphology. Neither was any relationship found between serum FSH and fertilization, cleavage, pregnancy and implantation rates, and the results of ICSI. These findings suggest the need to review the routine measurement of serum FSH in the infertile male when ICSI is the planned treatment procedure.   相似文献   
8.
BACKGROUND: Registries on outcome of ICSI pregnancies obtained with testicular sperm do not differentiate between obstructive (OA) and non-obstructive azoospermia (NOA). We evaluated the pregnancy outcome and neonatal data on children born after ICSI using testicular sperm of men with histologically proven OA or NOA. METHODS: Pregnancies obtained after ICSI using testicular sperm of men with defined NOA (n = 70) were compared with those of men with OA (n = 204). RESULTS: Multiple birth rates in NOA and OA couples, respectively, were 21 versus 27% (P = NS), overall preterm delivery rates were 38 versus 26% (NS), and prematurity rates were 24 versus 13% for singletons (NS) and 86 versus 54% for twins (relative risk 1.59, 95% confidence interval 1.04-2.42). Median gestational age for singletons was 38.3 versus 39.3 weeks, respectively (P < 0.05). The low birth weight rates were 34 versus 31%, respectively (NS). The early perinatal mortality rate was 66 versus 15 per 1000 births, respectively, (NS). Major congenital malformations were observed in 4 versus 3%, respectively, of the live born babies (NS). Prenatal karyotypes showed 7% de-novo abnormalities in the NOA group versus 1% in the OA group (NS). CONCLUSIONS: Our data do not show differences between NOA and OA pregnancies except for a strong tendency towards a lower gestational age in singletons and a higher percentage of premature twins in the NOA group. Although our data are based on a limited sample, the differences observed call for further analysis. Given the low pregnancy rates after ICSI with NOA, a multicentre study, differentiating NOA and OA patients, would be recommended.  相似文献   
9.
BACKGROUND: Eliciting an endogenous LH surge by GnRH-agonist for the induction of final oocyte maturation may be more physiological compared with the administration of HCG. However, the efficacy of this intervention in patients treated for IVF with GnRH antagonists remains to be assessed. METHODS: 106 patients were randomized to receive either 10 000 IU urinary HCG or 0.2 mg Triptorelin for triggering final oocyte maturation. Ovarian stimulation for IVF was performed with a fixed dose of 200 IU recombinant FSH and GnRH antagonist was started on stimulation day 6. Luteal phase was supported with micronized vaginal progesterone and oral estradiol. The study was monitored continuously for safety and stopping rules were established. RESULTS: No significant differences were present in the number of cumulus-oocyte complexes retrieved, in the proportion of metaphase II oocytes, in fertilization rates or in the number and quality of the embryos transferred between the two groups. However, a significantly lower probability of ongoing pregnancy in the GnRH agonist arm prompted discontinuation of the trial, according to the stopping rules established (odds ratio 0.11; 95% confidence interval 0.02-0.52). CONCLUSIONS: Lower probability of ongoing pregnancy can be expected when GnRH agonist is used for triggering final oocyte maturation instead of HCG in patients undergoing ovarian stimulation for IVF with GnRH antagonists.  相似文献   
10.
BACKGROUND: A pen device, similar to an insulin pen, has been recently marketed for the administration of follitropin beta in cartridges. A randomized controlled trial was performed to compare the efficacy and convenience of this pen device delivering follitropin beta with a conventional syringe delivering follitropin alpha. METHODS: A total of 200 patients needing IVF/ICSI treatment and willing to self-inject were enrolled in the study. All subjects had ovarian stimulation according to a long protocol and were randomized to the pen or the conventional syringe group during down-regulation by means of a computer-generated randomization list using random numbers. Patients were asked to fill in a daily local tolerance book after each injection. On the day of hCG the patients scored a Visual Analogue Scale (VAS) for pain and convenience. RESULTS: The average duration, total dose of recombinant FSH and number of cumulus oocyte complexes retrieved were 10.8/12.0 days (P = 0.001), 1880/2226 IU (P < 0.001) and 15.2/13.1 respectively in the pen device and conventional syringe groups; the presence of pain after the daily injection was significantly higher in the conventional syringe group (P = 0.027); the visual analogue scale score was similar for pain but significantly more convenient for the pen device (P < 0.001). The live birth rate per embryo transfer was 32.9 and 34.4% respectively in the pen device and conventional syringe groups. CONCLUSIONS: Self-injection with the pen device is safe and easy, more convenient and less painful for the patient, requires less FSH and shortens the treatment duration.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号