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   2196篇
  免费   155篇
  国内免费   20篇
儿科学   69篇
妇产科学   558篇
基础医学   360篇
口腔科学   5篇
临床医学   79篇
内科学   158篇
皮肤病学   9篇
神经病学   27篇
特种医学   10篇
外国民族医学   3篇
外科学   435篇
综合类   128篇
现状与发展   1篇
一般理论   1篇
预防医学   236篇
药学   88篇
中国医学   34篇
肿瘤学   170篇
  2024年   11篇
  2023年   42篇
  2022年   76篇
  2021年   110篇
  2020年   88篇
  2019年   111篇
  2018年   94篇
  2017年   82篇
  2016年   78篇
  2015年   64篇
  2014年   112篇
  2013年   211篇
  2012年   70篇
  2011年   104篇
  2010年   85篇
  2009年   84篇
  2008年   67篇
  2007年   78篇
  2006年   92篇
  2005年   79篇
  2004年   65篇
  2003年   47篇
  2002年   59篇
  2001年   42篇
  2000年   50篇
  1999年   26篇
  1998年   17篇
  1997年   28篇
  1996年   33篇
  1995年   19篇
  1994年   19篇
  1993年   18篇
  1992年   17篇
  1991年   17篇
  1990年   17篇
  1989年   16篇
  1988年   20篇
  1987年   21篇
  1986年   11篇
  1985年   16篇
  1984年   11篇
  1983年   11篇
  1982年   8篇
  1981年   5篇
  1980年   8篇
  1979年   15篇
  1978年   6篇
  1977年   2篇
  1976年   5篇
  1975年   3篇
排序方式: 共有2371条查询结果,搜索用时 17 毫秒
91.
Current therapy of childhood cancer makes long-term survival a realistic outcome for most patients. However, some treatment regimens entail a significant risk of infertility. No established method for preservation of female fertility is currently available. Ovarian cryopreservation is an experimental technology that is being offered with increasing frequency to women undergoing cancer therapy. It has not yet been reported in children and adolescent girls. The aim of this review is to stimulate discussion on the possibility of performing ovarian cryopreservation in pre-menarcheal girls in advance of therapies that may induce ovarian failure. We present a multi-disciplinary discussion of the risks and benefits associated with the procedure and propose guidelines for its implementation. We propose that all girls about to receive treatment that has a high risk for infertility be offered consultation about the possibility of ovarian cryopreservation.  相似文献   
92.
BACKGROUND To look at possible long-term risks from anabolic steroids and other xenobiotics in beef, we examined men's semen quality in relation to their mother's self-reported beef consumption during pregnancy. METHODS: The study was carried out in five US cities between 1999 and 2005. We used regression analyses to examine semen parameters in 387 partners of pregnant women in relation to the amount of beef their mothers reported eating while pregnant. Mothers' beef consumption was also analysed in relation to the son's history of previous subfertility. RESULTS Sperm concentration was inversely related to mothers' beef meals per week (P = 0.041). In sons of "high beef consumers" (>7 beef meals/week), sperm concentration was 24.3% lower (P = 0.014) and the proportion of men with sperm concentration below 20 x 10(6)/ml was three times higher (17.7 versus 5.7%, P = 0.002) than in men whose mothers ate less beef. A history of previous subfertility was also more frequent among sons of "high beef consumers" (P = 0.015). Sperm concentration was not significantly related to mother's consumption of other meat or to the man's consumption of any meat. CONCLUSIONS These data suggest that maternal beef consumption, and possibly xenobiotics in beef, may alter a man's testicular development in utero and adversely affect his reproductive capacity.  相似文献   
93.
BACKGROUND: Recent studies indicate that not only women's but also men's obesity has adverse effects on fecundity and since fecundity is a couple concept, we examined fecundity in relation to overweight and obesity of the couple. We also examined the association between weight changes and fecundity over time. METHODS: Between 1996 and 2002, 64 167 pregnant women enrolled in the Danish National Birth Cohort were interviewed during and 18 months after pregnancy. Information on body mass index (BMI) and waiting time to pregnancy (TTP) was available for 47 835 couples. RESULTS: Among men and women with a BMI of 18.5 kg/m(2) or more, we found a dose-response relationship between increasing BMI group and subfecundity (a TTP of more than 12 months): Odds ratio (OR) = 1.32 (95% CI: 1.26-1.37) for women and OR = 1.19 (95% CI: 1.14-1.24) for men. Among 2374 women with an initial BMI of 18.5 kg/m(2) or more, who participated more than once in the Danish National Birth Cohort, each kilogram increment in weight between the two pregnancies was associated with a 2.84 (95% CI: 1.33-4.35) days longer TTP. CONCLUSIONS: Couples have a high risk of being subfecund if they are both obese.  相似文献   
94.
The natural transmission of microdeletions of the Y chromosome is occasionally reported in the literature. Here we describe the natural transmission of a partial AZFb deletion over three generations. PCR amplification of several sequence tagged site markers in the three AZF regions of the Y chromosome was carried out in a patient with oligoasthenoteratozoospermia, his father and his naturally conceived son. The deletion was confirmed by Southern blotting. The propositum, his father and his son showed a probably identical, partial deletion of the distal part of the AZFb region, involving sY130 and sY143. The deletion was confirmed by Southern blotting using the sY130 probe. Partial AZFb microdeletions can be associated with moderate oligozoospermia allowing natural conception and therefore natural transmission of this genetic anomaly. Further studies are needed to define the pathogenetic significance of microdeletions involving sY130 and sY143.  相似文献   
95.
The predictive value of a comprehensive model with personality characteristics, stressor related cognitions, coping and social support was tested in a sample of 187 nonpregnant women. The emotional response to the unsuccessful treatment was predicted out of vulnerability factors assessed before the start of the treatment. The results indicated the importance of neuroticism as a vulnerability factor in emotional response to a severe stressor. They also underlined the importance of helplessness and marital dissatisfaction as additional risk factors, and acceptance and perceived social support as additional protective factors, in the development of anxiety and depression after a failed fertility treatment. From clinical point of view, these results suggest fertility-related cognitions and social support should receive attention when counselling women undergoing IVF or ICSI treatment.  相似文献   
96.
Fertility is a major part of the global care of patients treated for cancer. A new discipline known as oncofertility has emerged in some countries. Although the relationship between chemotherapy and external radiotherapy and fertility has been studied and reported, there is only scarce data available on brachytherapy. This systematic review aims to report available knowledge on the impact of brachytherapy on fertility. Specific consultations should be considered before brachytherapy to inform patients about their fertility preservation options.  相似文献   
97.
卵巢储备功能指卵巢内存留卵泡的数量和质量,其能间接地反映女性的生育能力。抗苗勒氏管激素(anti-Müllerian hormone,AMH)作为卵巢特异性的生长因子,由颗粒细胞分泌,是预测卵巢储备功能的一个有效指标。血清AMH的水平可以预测卵泡池的大小、卵巢的反应性及女性的绝经年龄,同时可以评估癌症患者的卵巢储备功能。但AMH的测定值受到多种因素的影响,存在一定的局限性。  相似文献   
98.
A recombinant chromosome with Xp duplication and Xq deletion was found in two sisters with normal height and gonadal dysgenesis. Their mother and other four relatives, including a fertile male, carried an inv(X)(p22q22); the inverted X was randomly inactivated in one female carrier. The abnormal X chromosome showed inactivation in all the examined cells. This is the tenth report of a recombinant X chromosome. A review of the literature shows that: i) most female carriers of inv(X) are phenotypically normal and fertile; ii) recombinants having short-arm duplication and long-arm deletion are associated with ovarian failure and normal or tall stature, whereas the reciprocal recombinants are compatible with fertility but cause short stature; and (ü) except for one index case, all male carriers have a normal phenotype and 11 of them (from eight families) are of proven fertility. Moreover, no instance of male infertility has been documented.  相似文献   
99.
Turner syndrome in a mother and daughter: r(X) and fertility   总被引:1,自引:0,他引:1  
A patient with mosaic Turner syndrome and normal fertility had three documented pregnancies. She had a 45,X/46,X,r(X) karyotype and did not undergo spontaneous sexual maturation and menarche. Conception occurred while on hormone replacement therapy. Her first pregnancy ended with the birth of a normal 46,XY male, while the third pregnancy resulted in a healthy 45,X/46,X,r(X) female. A review of the literature reveals a myriad of theories to account for the variability of ovarian function in Turner syndrome, but, as yet, there are insufficient data to yield any conclusions. There appears to be an increased risk of trisomy 21 in the offspring of females with Turner syndrome.  相似文献   
100.
Sleep loss increases blood–brain barrier permeability. As the blood–brain barrier and the blood–tissue barriers in the reproductive tract (blood–testis and blood–epididymis barriers) share common characteristics, we hypothesized that sleep restriction may also modify their barrier function. Previous reports showed that sleep loss decreased sperm viability and progressive fast mobility, which may be a consequence of altered blood–testis and blood–epididymis barrier. Therefore, we quantified changes in blood–testis and blood–epididymis barrier after sleep loss and related them to male fertility. Adult male Wistar rats were sleep restricted using the multiple‐platform technique in a protocol of 20 hr daily sleep deprivation plus 4 hr of sleep recovery in the home‐cage. At the 10th day, barrier permeability assays were performed with Na‐fluorescein, 10 kDa Cascade blue‐dextrans and Evans blue, and the expression of tight junction proteins, actin and androgen receptor was quantified. At the 10th day of sleep restriction and after sleep recovery days 1–7, males were placed with sexually receptive females, sexual behaviour was tested, and the percentage of pregnancies was calculated. Sleep restriction increased the barrier permeability to low‐ and high‐molecular‐weight tracers, and decreased the expression of tight junction proteins, actin and androgen receptor. Concomitantly, sleep restriction reduced the percentage of ejaculating males and the number of pregnancies. Sleep recovery for 2–3 days progressively re‐established fertility, as indicated by a higher percentage of ejaculating males and impregnated females. In conclusion, chronic sleep loss alters fertility concomitantly with the disruption of the blood–tissue barriers at the reproductive tract, the mechanism involves androgen signalling.  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