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   3077篇
  免费   281篇
  国内免费   67篇
耳鼻咽喉   5篇
儿科学   31篇
妇产科学   115篇
基础医学   303篇
口腔科学   19篇
临床医学   63篇
内科学   268篇
皮肤病学   56篇
神经病学   168篇
特种医学   14篇
外国民族医学   1篇
外科学   1227篇
综合类   231篇
预防医学   71篇
眼科学   29篇
药学   275篇
中国医学   56篇
肿瘤学   493篇
  2024年   9篇
  2023年   30篇
  2022年   59篇
  2021年   91篇
  2020年   93篇
  2019年   108篇
  2018年   104篇
  2017年   99篇
  2016年   101篇
  2015年   140篇
  2014年   166篇
  2013年   226篇
  2012年   161篇
  2011年   150篇
  2010年   155篇
  2009年   138篇
  2008年   179篇
  2007年   156篇
  2006年   153篇
  2005年   127篇
  2004年   132篇
  2003年   124篇
  2002年   92篇
  2001年   72篇
  2000年   48篇
  1999年   37篇
  1998年   51篇
  1997年   51篇
  1996年   45篇
  1995年   44篇
  1994年   24篇
  1993年   17篇
  1992年   13篇
  1991年   16篇
  1990年   14篇
  1989年   11篇
  1988年   19篇
  1987年   11篇
  1986年   17篇
  1985年   18篇
  1984年   16篇
  1983年   12篇
  1982年   22篇
  1981年   20篇
  1980年   11篇
  1979年   7篇
  1978年   15篇
  1977年   7篇
  1975年   5篇
  1974年   3篇
排序方式: 共有3425条查询结果,搜索用时 0 毫秒
71.
The primary aim of the present study was to determine the therapeutic dose of subcutaneous levonorgestrel (LNG) to induce azoospermia or severe oligozoospermia (<3 x 10(6)/mL) in normal men requiring contraception. Transdermal 5 alpha-dihydrotestosterone (DHT) was combined to the treatments to maintain peripheral androgen level. Forty-three 21-45-year-old healthy men were enrolled in this phase II randomised and comparative clinical performance study. The subjects were allocated to five groups to receive: (1) transdermal DHT (Andractim(R), Besins Iscovesco, Paris, France) and one subdermal LNG implant (Jadelle, Leiras, Turku, Finland); (2) transdermal DHT and two subdermal LNG implants; (3) transdermal DHT and four subdermal LNG implants; (4) transdermal DHT and oral LNG (Microluton, Schering, Germany); or (5) transdermal DHT only. A total of 27 men completed the suppression phase. None of them reached azoospermia. One subject with oral LNG and transdermal DHT reached <3 million/mL at 5 months of suppression, but not repeatedly. Together 2/27 (7%) subjects, one with oral LNG and DHT and the other with four subdermal LNG implants and DHT reached <5 million/mL temporarily. Altogether 9/27 (33%) subjects reached <20 million/mL. Serum testosterone concentrations (S-T) decreased significantly during the first 3 months of treatment with one, two and four LNG implants and DHT and during the next 3 months S-T remained significantly lower with two or four implants. Serum oestradiol concentrations (S-E(2)) decreased significantly during the first 3 months only with four implants, but at 6 months S-E(2) was lower also in the group with two implants. Serum luteinizing hormone (LH) decreased significantly only with two LNG implants and DHT gel at 5 and 6 months. Serum FSH did not decrease in any of the groups. None of the subjects filled the criteria to continue to the efficacy phase. A total of 16 men discontinued for various reasons. Of the 27 men completing the suppression phase, all have recovered to sperm levels >20 million/mL. There were no changes in blood count, lipid profile, liver function tests, prostate-specific antigen (PSA), sex hormone binding globulin (SHBG), prolactin or cortisol. The mixed antiglobulin reaction (MAR)-IgG, MAR-IgA or tray agglutination test (TAT) did not change during any of the treatments. The present study shows that the LNG implants themselves are well-tolerated by men and safe, and might be suitable for replacing part of the testosterone used as injections to reduce the androgen dose during male hormonal contraception. The DHT gel was considered as quite or very uncomfortable by 66% of the men because of feeling cold during the time it was on the skin, but noncompliance in using the gel was not reported by the men.  相似文献   
72.
In this retrospective study, we evaluated and compared the efficacy and toxicities of maximal androgen blockade (MAB) versus castration alone in Chinese patients with advanced prostate cancer. From 1996 to 2004, 608 patients with advanced prostate cancer were included in the study. Patients were retrospectively divided into two groups according to different therapeutic regimens. Of the 608 patients, 300 patients were treated with MAB (castration plus nonsteroidal antiandrogens) and the remaining 308 were treated with castration alone. The 2- and 5-year overall survival rates of these patients were 73.7% and 56%, respectively. Multivariate analysis showed that, in patients with metastatic prostate cancer, MAB was associated with not only the improvement of progression-free survival (PFS) (increased by 10 months) but also a 20.6% reduction in mortality risk compared with castration alone. In contrast, the efficacy of MAB was not superior to castration alone for patients with nonmetastatic prostate cancer. Interestingly, among patients with MAB, those using bicalutamide had a longer PFS than those using flutamide; this was especially so in patients with metastatic prostate cancer. Almost all of the toxicities due to the hormone therapy were mild to moderate and manageable. To conclude, in China, hormone therapies, including MAB and castration alone, have been standard treatments for advanced prostate cancer. For patients with nonmetastatic prostate cancer, castration alone might be adequately practical and efficient. In patients with metastatic prostate cancer, however, MAB has superior efficacy over castration alone. It is clear that MAB should be considered the first-line standard treatment for patients with metastatic prostate cancer.  相似文献   
73.
Partial androgen insensitivity syndrome (PAIS) is the milder variant of androgen receptor (AR) defects. The subtle effects of AR mutations present in a patient with micropenis, peno-scrotal hypospadias, infertility, clitoromegaly and posterior labial fusion. We studied the association of isolated micropenis with the genetic defects resulting in androgen resistance, that is, AR gene defects and 5-α reductase type 2 (SRD5A2) deficiency. We describe two cases of isolated micropenis: one in a 14-year-old boy and the other in a 3-year-old boy who was followed until he was 10 years old. There were no findings of hypospadias, cryptorchidism or gynecomastia in either of these patients. Serum gonadotrophin and androgen levels were obtained and karyotyping was done. Human chorionic gonadotropin (hCG) stimulation testing assessed the functional capacity of the testes. DNA was extracted from peripheral leukocytes, and all exons of the SRD5A2 and AR genes were amplified by polymerase chain reaction and sequenced. In both patients, baseline testosterone (T) level was low and the values were elevated after hCG testing. The sequence of the SRD5A2 gene was normal in patient 1, and a heterozygous polymorphism, V89L, was found in patient 2. Two known mutations, P390S and A870V, were identified in patients 1 and 2, respectively. Mutations in the AR gene can be associated with isolated micropenis without other features of PAIS, such as hypospadias or gynecomastia. This underlines the importance of including AR gene analysis in the evaluation of isolated micropenis with normal plasma T to ensure proper management of the patient and appropriate genetic counseling for the family.  相似文献   
74.
种族、家族史和年龄是众所周知的前列腺癌危险因素。雄激素受体依赖性信号传送是前列腺癌变和肿瘤转移的重要基础。非裔男性的前列腺癌发病率、死亡率高于白人,且临床恶性程度高。本实验探究了非裔男性家族性前列腺癌与雄激素受体(AR)基因突变之间的关系。实验中我们对参与路易斯安那州立大学健康科学中心前列腺癌遗传连锁研究的30个高危黑人和白人家庭的60名前列腺癌患者的基因组HDNA序列进行了检测。应用外显子特异性聚合酶链反应,双向自动测序和限制性内切酶基因分型分析AR基因编码区突变,结果在一个有早发前列腺癌家族史黑人家庭的3名成员中发现了种系AR-A1675T(T559S)替换突变,突变位于DNA结合区。本研究首次在患家族性前列腺癌的黑人男性中发现了种系雄激素受体突变,该突变可能会改变受体与DNA结合亲和力和/或对雄激素、非雄性类固醇或雄激素拈抗剂的反应。今后的研究应当探索AR(A1675T)序列对黑人早发和/或家族性前列腺癌的影响和影响频率。  相似文献   
75.
To gain beneficial effects in the management of high-risk prostate cancer, an integrated approach that combines local therapy and androgen deprivation therapy (ADT) was used. We compared biochemical responses between primary cryosurgical ablation of the prostate (CSAP) combined with prolonged ADT and radiation combined with ADT, which is the established modality in high-risk disease. A total of 33 high-risk patients received CSAP combined with ADT for 3 months before and up to 24 months after treatment. This patient group was matched with another 33 patients who had undergone three-dimensional conformal radiation therapy (3D-CRT) with the same protocol for ADT. Biochemical recurrence (BCR) was assessed by the American Society for Therapeutic Radiation Oncology (ASTRO) definition, the Phoenix definition and a prostate-specific antigen (PSA) cutoff of 0.5 ng mL^-1. Median follow-up was 61.0 ± 11.9 months for the CSAP + ADT group and 86.0±15.8 months for the 3D-CRT + ADT group. In the CSAP group, major complications including rectourethral fistula and incontinence were not noted. In the CSAP + ADT group, 57.0% had BCR using the ASTRO definition, 21.2% using the Phoenix definition and 54.5% using a PSA cutoff of 0.5 ng mL^-1. In the 3D-CRT + ADT group, 54.5%, 21.2% and 54.5% had BCR using the ASTRO, Phoenix and PSA definition, respectively. In the CSAP + ADT group, the BCR-free survival (BRFS) was 54 ± 10 months using the ASTRO definition, 65 ± 5 months using the Phoenix definition and 51 ± 4 months using a PSA cutoff of 0.5 ng mL-1. In the 3D-CRT + ADT group, the BRFS was 68 ± 12, 93 ± 19 and 70 ± 18 months using the ASTRO, Phoenix and PSA definition, respectively. By the log-rank test, the BRFS values for each group were not statistically different. This intermediate-term result indicated that primary CSAP combined with prolonged ADT offers a parallel biochemical response compared with radiotherapy in high-risk prostate cancer.  相似文献   
76.
77.
78.
79.
目的探讨一种新的人工合成CK2选择性抑制剂四溴肉桂(TBCA),对前列腺癌细胞增殖及周期的影响。方珐CK2选择性抑制剂TBCA应用到多种前列腺癌细胞系,Alamarblue法和克隆形成实验检测细胞生长和增殖能力,流式细胞技术检测细胞周期分布,治疗组与对照组间差异是否具有显著意义采用SPSS统计软件进行分析。站杲低剂量(〈25μmol)TBCA干预下未发现细胞聚集和分离,而在高剂量(〉50μmol)则可观察到细胞明显分离,剂量依赖性抑制细胞生长和增殖(P〈0.05),半抑制浓度值(IC50)为25μmol。TBCA诱导前列腺癌细胞停滞在G2/M期细胞周期。结论TBCA呈剂量依赖性抑制前列腺癌细胞增殖和细胞周期停滞在G2/M期。  相似文献   
80.
BACKGROUND: Changes in steroid ratios seen in the aging male are thought to promote prostate disease. The aims of this study were to compare the effects of varied ratios of steroids on growth of normal stromal and epithelial cell isolates, and the prostate cancer cell line, LNCaP. METHODS: The effect of altered steroid ratios on cell proliferation of normal stromal (PrSC) and epithelial (PrEC) prostate cells, and the malignant cell line, LNCaP, were assessed. RESULTS: Increasing the ratios of both estrogen:dihydrotestosterone (DHT) and DHT:estrogen, stimulated PrSC proliferation, with increasing estrogen:DHT having the greatest effect. LNCaP proliferation was increased significantly by both steroids, but altered ratios had no additional effect. PrEC proliferation was unaffected when cells were grown alone, despite presence of androgen receptors (AR) and estrogen receptors (ER). When grown in co-culture PrEC cell proliferation was significantly increased by treatments. CONCLUSIONS: PrSC proliferation is stimulated by an increasing ratio of estrogen:androgen. Proliferation of normal epithelial cells is stimulated as a result of an indirect action of steroids mediated by stromal cells. Malignant prostate cancer cells have an altered response in comparison.  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