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   5128篇
  免费   265篇
  国内免费   31篇
耳鼻咽喉   54篇
儿科学   215篇
妇产科学   108篇
基础医学   436篇
口腔科学   147篇
临床医学   537篇
内科学   1300篇
皮肤病学   66篇
神经病学   233篇
特种医学   126篇
外科学   1068篇
综合类   72篇
一般理论   1篇
预防医学   320篇
眼科学   119篇
药学   318篇
中国医学   27篇
肿瘤学   277篇
  2023年   38篇
  2022年   95篇
  2021年   184篇
  2020年   90篇
  2019年   148篇
  2018年   214篇
  2017年   123篇
  2016年   145篇
  2015年   139篇
  2014年   291篇
  2013年   298篇
  2012年   461篇
  2011年   500篇
  2010年   272篇
  2009年   199篇
  2008年   335篇
  2007年   329篇
  2006年   316篇
  2005年   240篇
  2004年   248篇
  2003年   211篇
  2002年   225篇
  2001年   30篇
  2000年   15篇
  1999年   29篇
  1998年   31篇
  1997年   30篇
  1996年   25篇
  1995年   18篇
  1994年   16篇
  1993年   16篇
  1992年   10篇
  1991年   7篇
  1990年   8篇
  1989年   7篇
  1988年   7篇
  1987年   3篇
  1986年   2篇
  1985年   7篇
  1984年   6篇
  1983年   3篇
  1982年   6篇
  1981年   5篇
  1980年   11篇
  1979年   3篇
  1977年   5篇
  1974年   4篇
  1972年   3篇
  1971年   2篇
  1962年   2篇
排序方式: 共有5424条查询结果,搜索用时 15 毫秒
21.
22.
Cancer is a leading cause of death worldwide and affects society in terms of the number of lives lost. Current cancer treatments are based on conventional chemotherapy which is nonspecific in targeting cancer. Therefore, intensive efforts are underway to better target cancer-specific cells while minimizing the side effects on healthy tissues by using LDL particles as active drug delivery vehicles. The goal is to encapsulate anticancer agents thiosemicarbazone metal-ligand complexes into LDL particles to increase the cytotoxic effect of the agent by internalization through LDL receptors into MCF7, A549, and C42 cancer cell lines as segregate models for biological evaluations targeting tubulin. Zeta potential data of LDL-particles encapsulated anticancer agents showed an acceptable diameter range between 66–91 nm and uniform particle morphology. The results showed cell proliferation reduction in all tested cell lines. The IC50 values of LDL encapsulated thiosemicarbazone metal-ligand complexes treated with MCF7, A549, and C42 ranged between 1.18–6.61 µM, 1.17–9.66 µM, and 1.01–6.62 µM, respectively. Western blot analysis showed a potent decrease in tubulin expression when the cell lines were treated with LDL particles encapsulated with thiosemicarbazone metal-ligand complexes as anticancer agents. In conclusion, the data provide strong evidence that LDL particles are used as an active drug delivery strategy for cancer therapy.  相似文献   
23.
A novel series of glass, consisting of B2O3, Bi2O3, TeO2, and TiO2 (BBTT) containing rare earth oxide RE2O3, where RE is La, Ce, Sm, Er, and Yb, was prepared. We investigated the structural, optical, and gamma attenuation properties of the resultant glass. The optical energy bands, the linear refractive indices, the molar refractions, the metallization criteria, and the optical basicity were all determined for the prepared glass. Furthermore, physical parameters such as the density, the molar volume, the oxygen molar volume, and the oxygen packing density of the prepared glass, were computed. Both the values of density and optical energy of the prepared glass increased in the order of La2O3, Ce2O3, Sm2O3, Er2O3, and then Yb2O3. In addition, the glass doped with Yb2O3 had the lowest refractive index, electronic polarizability, and optical basicity values compared with the other prepared glass. The structures of the prepared glass were investigated by the deconvolution of infrared spectroscopy, which determined that TeO4, TeO3, BO4, BO3, BiO6, and TiO4 units had formed. Furthermore, the structural changes in glass are related to the ratio of the intensity of TeO4/TeO3, depending on the type of rare earth. It is also clarified that the resultant glass samples are good attenuators against low-energy radiation, especially those that modified by Yb2O3, which exhibited superior shielding efficiency at energies of 622, 1170, and 1330 keV. The optical and gamma ray spectroscopy results of the prepared glass show that it is a good candidate for nonlinear optical fibers, laser solid material, and optical shielding protection.  相似文献   
24.
A eucaloric very low carbohydrate diet (EVLCD) is a diet with a daily caloric intake equal to the total daily energy expenditure (TDEE) with a carbohydrate content of <50 g/day. The literature on very low carbohydrate diets (VLCD) in type 1 diabetes (DM 1) is limited, although recently published scientific studies have highlighted their safety and efficacy in managing DM 1. In this retrospective analysis, we report the clinical data of 33 patients affected by DM 1 carrying out insulin therapy who switched voluntarily from their usual diet (high carb, low fat) to an EVLCD. Our aim is to evaluate the glycemic control, the amount of insulin needed in order to maintain glycemic control and safety of EVLCD. The switch improved glycemic control (mean glycated hemoglobin decreased from 8.3% to 6.8% (p < 0.01). The number of patients who reached a glycated hemoglobin value of <7% increased statistically from 12% to 57% (p < 0.01), and there was a statistically significant decrease (p < 0.01) in the units of daily insulin (from 36.7± 14.9 IU to 28.9 ±9.1 IU) A reduction from 54% to 24% in clinical level 2 hypoglycemia episodes was reported. No cases of severe hypoglycemia or ketoacidosis were observed. The results of the study support that EVLCD in DM 1 seems safe and effective when adopted under tight medical supervision.  相似文献   
25.
BACKGROUND: Duplicated collecting systems comprises renal units containing two pyelocalyceal systems associated with a single ureter or double ureters and is the most common upper tract anomaly. CASE: This report presents a rare entity: an adult woman who had giant hydroureter of upper-pole moiety of the duplex kidney, which was an incidental finding during cesarean section. Heminephroureterectomy was done containing 2 L of fluid. This case is the first of its kind during cesarean section. CONCLUSION: The cause of this unusually massive degree of dilatation of the upper-pole moiety of the duplicated collecting system is uncertain, but may have resulted from an error in the development or because of VUR. We suggest mandatory intraabdominal examination after delivering uterus while conducting a cesarean section.  相似文献   
26.
27.
Since the beginning of IVF, natural cycle In Vitro Fertilization (NC-IVF) has been largely replaced by IVF with ovarian stimulation. However, natural cycle IVF has several advantages: low cost, no risk of ovarian hyper stimulation syndrome, very low risk of multiple pregnancy. Nevertheless, natural cycle IVF is less effective with a high risk of cancellation due to premature rise of LH, and an increased risk of failed oocyte retrieval. Using GnRH antagonists in a modified natural cycle decreases the occurrence of a premature LH rise. In the context of a poor responder patient, natural IVF could theoretically yield a better quality oocyte coming from a naturally selected follicle and allow a transfer on an endometrium whose receptivity has not been distorted by controlled ovarian stimulation. However, the real place for it has yet to be defined as we lack published data. Only one randomised controlled study in poor responders showed a similar pregnancy rate to a standard protocol representing a cost-effective alternative. Available retrospective data seem to show the same trend especially in the sub group of younger patients (below 38). Natural cycle IVF is a low-risk, low-cost procedure whose interesting results should be further confirmed by large scale prospective studies.  相似文献   
28.
29.
30.
BACKGROUND: It has been suggested that there exists a close relationship between seizure discharges and functional recovery from brain injury, and that paroxysmal bombardment in late seizures may herald functional recovery or may "kick-start" recovery. CASE REPORT: We report the case of a 52-year-old patient who, following a subarachnoid hemorrhage and multiple surgeries, experienced discernible apallic syndrome of long duration. His hospitalization is well documented. The patient underwent protracted, intense rehabilitation, but he remained in this prolonged state of loss of consciousness and behavioral passivity until he experienced a series of periodic seizures. Widespread improvement in his cognitive and functional abilities coincided closely with the seizure activity. The literature on this topic is reviewed. CONCLUSION: This case confirms the close relationship between seizure discharges and functional recovery reported in preclinical literature.  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