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   1405篇
  免费   64篇
  国内免费   3篇
耳鼻咽喉   10篇
儿科学   95篇
妇产科学   64篇
基础医学   252篇
口腔科学   18篇
临床医学   127篇
内科学   268篇
皮肤病学   20篇
神经病学   154篇
特种医学   19篇
外科学   173篇
综合类   6篇
一般理论   7篇
预防医学   137篇
眼科学   18篇
药学   71篇
肿瘤学   33篇
  2021年   21篇
  2020年   21篇
  2019年   21篇
  2018年   18篇
  2017年   14篇
  2016年   31篇
  2015年   19篇
  2014年   33篇
  2013年   63篇
  2012年   99篇
  2011年   68篇
  2010年   33篇
  2009年   48篇
  2008年   81篇
  2007年   83篇
  2006年   73篇
  2005年   82篇
  2004年   64篇
  2003年   55篇
  2002年   68篇
  2001年   42篇
  2000年   43篇
  1999年   30篇
  1998年   14篇
  1997年   24篇
  1996年   11篇
  1995年   15篇
  1994年   10篇
  1993年   14篇
  1992年   22篇
  1991年   17篇
  1990年   19篇
  1989年   16篇
  1988年   10篇
  1987年   14篇
  1986年   15篇
  1985年   12篇
  1984年   8篇
  1982年   6篇
  1979年   8篇
  1978年   7篇
  1976年   7篇
  1975年   7篇
  1973年   6篇
  1972年   6篇
  1971年   8篇
  1970年   8篇
  1969年   7篇
  1967年   12篇
  1966年   8篇
排序方式: 共有1472条查询结果,搜索用时 15 毫秒
1.
2.
3.
In this open, prospective, phase-I study we closely monitored levels of endogenous progesterone, 17beta-estradiol, luteinizing hormone (LH) and follicle stimulating hormone in six healthy women. We determined plasma concentrations every 1-3 days during one untreated baseline cycle and during the first treatment cycle with regular pill intake of an oral contraceptive containing 30 microg ethinylestradiol plus 75 microg gestodene. During the following two treatment cycles, two tablets were deliberately omitted (in cycle 2 on days 6/7 and in cycle 3 on days 11/12). All but possibly one volunteer ovulated in the untreated pre-cycle, as concluded from LH peaks followed by marked increases of progesterone. During the regular first treatment cycle and even after deliberate omission of two tables in treatment cycles 2 and 3, the progesterone and estradiol levels remained low, so that we concluded that no ovulation took place. However, two volunteers showed some sort of LH peak in the first regular treatment cycle and all women showed LH increases of > 40 microg/ml in at least one omission cycle. In ten out of 12 cycles, omissions of pill intake were followed by an episode of intermenstrual bleeding. In conclusion, we have shown that, after omission of two consecutive oral contraceptive tables, the endogenous hormone parameters did not provide evidence for ovulation. Although this provides confirmation of the robustness of this oral contraceptive towards non-compliance, the widely published practical recommendations should be followed.  相似文献   
4.
OBJECTIVE: To develop a universal guideline allowing the comparison of interventions like oral contraceptives and hormone replacement therapy with an impact on menstrual bleeding pattern. METHODS: Literature analysis and cluster analysis of 4612 bleeding diaries. RESULTS: We summarized key definitions needed for the evaluation of menstrual bleeding patterns from the literature. We developed a methodology to systematically evaluate menstrual bleeding patterns that distinguishes between cyclical and continuous hormonal regimens. CONCLUSION: This universal guideline can be applied to all prospective clinical studies that affect menstrual bleeding patterns. It allows regulatory agencies and prescribing physicians to make meaningful comparisons of different products.  相似文献   
5.
A 15-year-old boy is described with myasthenia gravis, hemophilia A, positive HTLV-III serology, antithyroglobulin and antimicrosomal antibodies, and laboratory evidence of altered cell-mediated immunity. Treatment with pyridostigmine produced dramatic clinical improvement. The results of this patient raise the possibility of myasthenia gravis as the sole or presenting clinical manifestation of infection with HTLV-III.  相似文献   
6.
Previous studies have shown a positive relationship between intrusions, effortful avoidance and overgeneral memory in people suffering from (mild) depression or PTSD. The purpose of the present study was to investigate these relationships in a non‐clinical sample. As part of a mass testing session, a written version of the Autobiographical Memory Test was administered to 175 first‐year psychology students. Furthermore, intrusion and avoidance symptoms were measured with the Impact of Event Scale (Horowitz, Wilner, & Alvarez, 1979), and depressive symptoms with the Beck Depression Inventory (Beck, Ward, Mendelson, Mock, & Erbaugh, 1961). The data demonstrated a significant correlation between avoidance symptoms and categoric memory to negative cue words. This relationship remained significant after controlling for depressive symptoms. These results concur with other findings that overgeneral memory tends to be related to symptoms of effortful avoidance. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
7.
Head circumference is considered an important parameter of brain growth and development. Syndrome-specific standards for head circumference in Williams-Beuren syndrome (WBS) are not available to date, although mental retardation is a leading manifestation in the syndrome. Therefore, we investigated head growth in 63 girls (251 measurements) and 88 boys (298 measurements) with WBS between birth and adulthood. Most measurements in both sexes were from the first 4 years of life (n = 162 in girls and n = 189 in boys). Mean (±SD) head circumference at birth was 33.39 ± 1.38 cm and 34.02 ± 1.44 cm for term girls and boys, respectively. Although head growth in WBS girls and boys was at a slower velocity, the pattern of head circumference was similar to that in the normal population. After the age of 3 months, head circumference started to fall below the normal mean in girls (0.5–2 cm). In boys, mean head circumference was below the normal mean already at 1 month of age (2 cm). The deficit increased to 3 cm from 6 months to 4 years. Adult OFC was 52.85 ± 1.75 cm (n = 16) compared to 55.70 ± 1.83 cm (n = 46; P < 0.00001) in WBS women and 55.51 ± 1.68 cm (n = 30) compared to 57.87 ± 1.29 cm (n = 31; P < 0.00001) in WBS men. During development, microcephaly is only seen in about one third of WBS patients. © 1994 Wiley-Liss, Inc.  相似文献   
8.
The location of the cells of origin of the propriospinal and long ascending spinal fibers has been determined by injecting horseradish peroxidase (HRP) unilaterally into the white and gray matter of the cat's spinal cord at cervical, thoracic and lumbar levels. In all cases retrogradely labeled neurons were present in the intermediate zone throughout the spinal cord. Caudal to the injections labeled neurons were also present in the dorsal horn, the column of Clarke and the area of the spinal border cells.  相似文献   
9.
In recent years, the infrahyoid muscles (IHM) have been used by plastic reconstructive surgeons as a neurovascular muscle flap in the neck and mouth region. METHODS: A preoperative electromyographic examination (EMG) of the IHM was performed in 10 patients, of whom 9 suffered from tongue cancer, in order to detect neurogenic lesions caused by possible metastases or lymph nodes. The results were compared to those of 10 healthy controls. RESULTS: The EMG at rest showed no pathological spontaneous activity in any patient. During light voluntary innervation, the motor unit potentials (MUPs) were normal in controls and in patients with normal sonographic images, computertomographic scans, and histologic findings after surgery in the neck region. When metastatic lymph nodes were found on one side of the neck, the number of polyphasic MUPs in the IHM of that side was increased in some cases (n = 6), and normal in others (n = 5). Traumatic or radiogenic lesions clearly resulted in pathological EMG findings (n = 6). A maximal innervation of the IHM was achieved during head bending and jaw opening, there was no activation of the IHM with tongue movements and vice versa. CONCLUSIONS: If the presence of lymph node pathology was demonstrated using imaging techniques, a resulting lesion of the ansa cervicalis can functionally be demonstrated by EMG. In patients without lymph node metastases and without concurrent other lesions in the cervical region, EMG of the IHM seems to give no further clinical information. A clear postoperative functional differentiation of the transplanted IHM and the indigenous tongue muscles is possible.  相似文献   
10.
We have examined the mutational basis of adenine phosphoribosyltransferase (APRT, EC 2.4.2.7) deficiency (MIM 102600) in a patient of Polish origin who has been passing 2,8-dihydroxyadenine (DHA) stones since birth, but has considerable residual enzyme activity in lymphocyte extracts. The five exons and flanking regions of APRT were amplified by PCR and then sequenced. A single T insertion was identified at the intron 4 splice donor site (TGgtaa to TGgttaa:IVS4+2insT) in one allele from the proband, his mother, and brother. A G-to-T transversion in exon 5 (GTC-to-TTC:c.448G>T, V150F) was identified in the other allele, and this mutation was also present in one allele from the father and the paternal grandmother. Tru91 and AvaII digestions of PCR products spanning exons 4 and 5, respectively, confirmed the mutations. The mother was heterozygous for an intragenic TaqI site, but all other family members were homozygous for the presence of this site. IVS4+2insT, located on the allele containing the TaqI site, has been identified previously in several families from Europe, suggesting a founder effect, but the substitution in exon 5 is a novel mutation. IVS4+2insT is known to result in complete loss of enzyme activity, and our results suggest that V150F produces an enzyme that is nonfunctional in vivo but has considerable residual activity in vitro.  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