全文获取类型
收费全文 | 2133篇 |
免费 | 124篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 25篇 |
儿科学 | 153篇 |
妇产科学 | 56篇 |
基础医学 | 264篇 |
口腔科学 | 69篇 |
临床医学 | 167篇 |
内科学 | 465篇 |
皮肤病学 | 57篇 |
神经病学 | 137篇 |
特种医学 | 110篇 |
外科学 | 226篇 |
综合类 | 38篇 |
一般理论 | 2篇 |
预防医学 | 74篇 |
眼科学 | 48篇 |
药学 | 176篇 |
中国医学 | 11篇 |
肿瘤学 | 182篇 |
出版年
2023年 | 14篇 |
2022年 | 47篇 |
2021年 | 80篇 |
2020年 | 41篇 |
2019年 | 65篇 |
2018年 | 74篇 |
2017年 | 54篇 |
2016年 | 82篇 |
2015年 | 51篇 |
2014年 | 102篇 |
2013年 | 120篇 |
2012年 | 179篇 |
2011年 | 177篇 |
2010年 | 94篇 |
2009年 | 74篇 |
2008年 | 116篇 |
2007年 | 111篇 |
2006年 | 106篇 |
2005年 | 94篇 |
2004年 | 93篇 |
2003年 | 70篇 |
2002年 | 71篇 |
2001年 | 27篇 |
2000年 | 22篇 |
1999年 | 28篇 |
1998年 | 11篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1992年 | 16篇 |
1991年 | 19篇 |
1990年 | 15篇 |
1989年 | 16篇 |
1988年 | 12篇 |
1987年 | 18篇 |
1986年 | 18篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 12篇 |
1982年 | 6篇 |
1980年 | 6篇 |
1979年 | 11篇 |
1978年 | 11篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 6篇 |
1974年 | 7篇 |
1973年 | 4篇 |
1972年 | 6篇 |
1970年 | 6篇 |
1969年 | 6篇 |
排序方式: 共有2260条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Relative permeability of nasal, tracheal, and bronchoalveolar mucosa to macromolecules in rats exposed to ozone 总被引:2,自引:0,他引:2
D K Bhalla R C Mannix M T Kleinman T T Crocker 《Journal of toxicology and environmental health》1986,17(2-3):269-283
Nasal, tracheal and bronchoalveolar injuries resulting from acute ozone exposure of rats were investigated by permeability changes. 99mTc-labeled diethylenetriaminepentaacetate (DPTA) and 125I-labeled bovine serum albumin (BSA) were selectively instilled into localized airway regions of anesthetized rats exposed to 0.8 ppm 03 or clean air for 2 h. Transmucosal transfer of the radiolabeled tracers was detected by counting the radioactivity in blood samples collected at short postinstillation time intervals. Permeability measurements were made on d 0, 1, and 2 after O3 exposure to analyze the extent and persistence of tissue injury in the nasal, tracheal, and bronchoalveolar regions. Normal mucosal permeability was low in nose, intermediate in bronchoalveolar zone, and high in trachea. The O3-related injury, reflected by elevated permeability, was substantial in the trachea and bronchoalveolar zone but was minimal in the nose immediately after the exposure. Abnormal permeability persisted for less than 24 h in the trachea but for more than 24 h in the bronchoalveolar zone. The results are consistent with the properties of O3 of causing greater injury in the smaller airways and the alveolar zone than in the trachea. 相似文献
5.
6.
7.
Kapil N Bhalla 《Journal of clinical oncology》2005,23(17):3971-3993
Epigenetic regulation of gene expression is mediated through alterations in the DNA methylation status, covalent modifications of core nucleosomal histones, rearrangement of histones, and by RNA interference. It is now abundantly clear that deregulation of epigenetic mechanisms cooperates with genetic alterations in the development and progression of cancer and leukemia. Epigenetic deregulation affects several aspects of tumor cell biology, including cell growth, cell cycle control, differentiation, DNA repair, and cell death. This raises the strong possibility that reversing deregulated epigenetic mechanisms may be an effective treatment strategy for leukemia and cancer. This treatment strategy may either be designed to separately or collectively target the specific perturbations in the epigenetic mechanisms found in human hematologic malignancies. The following review describes our current understanding of the important deregulated epigenetic mechanisms and the preclinical and clinical development of epigenetic and chromatin modifiers in the therapy of these disorders. 相似文献
8.
Shilpa Jagatram Tomar Kalichamy Alagarasu Ashwini More Manasi Nadkarni Rupali Bachal Minal Bote Jayashri Patil Vasanthy Venkatesh Deepti Parashar Babasaheb Vishwanath Tandale 《Viruses》2022,14(5)
Chikungunya virus (CHIKV) is an arthropod-borne virus capable of causing large outbreaks. We aimed to determine the decadal change in the extent of chikungunya virus infection from 2009 to 2019. We implemented a prospective cross-sectional survey in Pune City using a 30-cluster approach with probability-proportion-to-size (PPS) sampling, with blood samples collected from 1654 participants in early 2019. The study also included an additional 799 blood samples from an earlier serosurvey in late 2009. The samples were tested by an in-house anti-CHIKV IgG ELISA assay. The overall seroprevalence in 2019 was 53.2% (95% CI 50.7–55.6) as against 8.5% (95% CI 6.5–10.4) in 2009. A fivefold increase in seroprevalence was observed in a decade (p < 0.00001). The seroprevalence increased significantly with age; however, it did not differ between genders. Modeling of age-stratified seroprevalence data from 2019 coincided with a recent outbreak in 2016 followed by the low-level circulation. The mean estimated force of infection during the outbreak was 35.8% (95% CI 2.9–41.2), and it was 1.2% after the outbreak. To conclude, the study reports a fivefold increase in the seroprevalence of chikungunya infection over a decade in Pune City. The modeling approach considering intermittent outbreaks with continuous low-level circulation was a better fit and coincided with a recent outbreak reported in 2016. Community engagement and effective vector control measures are needed to avert future chikungunya outbreaks. 相似文献
9.
Endocannabinoids are lipid signalling molecules that are related to the major psychoactive component in marijuana, delta-9-tetrahydrocannabinol and are increasingly recognized as being important in implantation and development of early embryos. The endocannabinoid anandamide, is metabolized by the enzyme fatty acid amide hydrolase (FAAH), and insufficient levels of this enzyme have been implicated in spontaneous miscarriage in women and implantation failure in mice. We screened placental bed biopsies and placental tissue from 45 women with recurrent miscarriage and 17 gestation-matched women with normal pregnancies for the expression of FAAH by immunohistochemistry. Unexpectedly, the enzyme appeared to be localised to the nucleus of trophoblasts and this was confirmed by western blotting of sub-cellular fractions and confocal microscopy. FAAH was expressed in the cytoplasm of large decidual stromal cells and significantly more women with recurrent miscarriage (73%) expressed FAAH in these cells than women with normal pregnancy (31%). FAAH was also expressed in the nucleus of extravillous trophoblasts that had invaded the decidua from 67% of women with recurrent miscarriage but was not expressed by these cells in any women with normal pregnancies. In contrast, FAAH was expressed in extravillous trophoblasts that had migrated out of the villi but that had not yet invaded the decidua in both normal pregnancies and in cases of recurrent miscarriage. FAAH was also present in the nucleus of a small number of villous trophoblasts in some specimens. FAAH appears to be over expressed in trophoblasts that have invaded the decidua, as well as in large decidual stromal cells in many cases of recurrent miscarriage. This may reflect inadequate control of the cannabinoid system in the uterus of women who experience recurrent miscarriages. The functional significance of the unexpected nuclear localisation of FAAH in trophoblasts is not yet clear. 相似文献
10.
Omar SZ Qvist R Khaing SL Muniandy S Bhalla S 《The journal of obstetrics and gynaecology research》2008,34(2):174-178
AIM: The aim of the present study was to determine the existence or prevalence of thrombophilic markers such as Factor V Leiden, prothrombin G20210A, protein S, protein C, activated protein C and anti-thrombin in pre-eclampsia and pregnancy-induced hypertensive patients. METHODS: Blood samples were collected from a total number of 124 women at the maternity unit, University of Malaya Medical Center. These included 49 patients with pre-eclampsia, 63 patients with pregnancy-induced hypertension and 12 normal pregnant women. DNA was extracted from the blood samples. Factor V Leiden (Taq I) and prothrombin G20210A (Hind III) genotyping was done on polymerase chain reaction-restriction fragment length polymorphism. Anti-thrombin activity and the concentrations of protein C, protein S and activated protein C were measured using the IL Coagulation System (Hemosil). RESULTS: Of the 124 subjects, one pre-eclampsia patient was homozygous for Factor V Leiden mutation but prothrombin G20210A mutation was not present in any of the subjects. The subject with Factor V Leiden mutation also had a low activated protein C resistance and a low protein S concentration. CONCLUSIONS: Factor V Leiden mutation is present in the Asian population and may very well serve as one of the genetic factors responsible for pre-eclampsia and other adverse pregnancy outcomes. 相似文献